thodg/libgit2

diff --git a/include/git2.h b/include/git2.h
index e182ce9..9239b48 100644
--- a/include/git2.h
+++ b/include/git2.h
@@ -9,6 +9,7 @@
 #define INCLUDE_git_git_h__
 
 #include "git2/annotated_commit.h"
+#include "git2/apply.h"
 #include "git2/attr.h"
 #include "git2/blob.h"
 #include "git2/blame.h"
diff --git a/include/git2/apply.h b/include/git2/apply.h
new file mode 100644
index 0000000..7cc1c22
--- /dev/null
+++ b/include/git2/apply.h
@@ -0,0 +1,129 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_git_apply_h__
+#define INCLUDE_git_apply_h__
+
+#include "common.h"
+#include "types.h"
+#include "oid.h"
+#include "diff.h"
+
+/**
+ * @file git2/apply.h
+ * @brief Git patch application routines
+ * @defgroup git_apply Git patch application routines
+ * @ingroup Git
+ * @{
+ */
+GIT_BEGIN_DECL
+
+/**
+ * When applying a patch, callback that will be made per delta (file).
+ *
+ * When the callback:
+ * - returns < 0, the apply process will be aborted.
+ * - returns > 0, the delta will not be applied, but the apply process
+ *      continues
+ * - returns 0, the delta is applied, and the apply process continues.
+ *
+ * @param delta The delta to be applied
+ * @param payload User-specified payload
+ */
+typedef int (*git_apply_delta_cb)(
+	const git_diff_delta *delta,
+	void *payload);
+
+/**
+ * When applying a patch, callback that will be made per hunk.
+ *
+ * When the callback:
+ * - returns < 0, the apply process will be aborted.
+ * - returns > 0, the hunk will not be applied, but the apply process
+ *      continues
+ * - returns 0, the hunk is applied, and the apply process continues.
+ *
+ * @param hunk The hunk to be applied
+ * @param payload User-specified payload
+ */
+typedef int (*git_apply_hunk_cb)(
+	const git_diff_hunk *hunk,
+	void *payload);
+
+/**
+ * Apply options structure
+ *
+ * Initialize with `GIT_APPLY_OPTIONS_INIT`. Alternatively, you can
+ * use `git_apply_init_options`.
+ *
+ * @see git_apply_to_tree, git_apply
+ */
+typedef struct {
+	unsigned int version;
+
+	git_apply_delta_cb delta_cb;
+	git_apply_hunk_cb hunk_cb;
+	void *payload;
+} git_apply_options;
+
+#define GIT_APPLY_OPTIONS_VERSION 1
+#define GIT_APPLY_OPTIONS_INIT {GIT_APPLY_OPTIONS_VERSION}
+
+/**
+ * Apply a `git_diff` to a `git_tree`, and return the resulting image
+ * as an index.
+ *
+ * @param out the postimage of the application
+ * @param repo the repository to apply
+ * @param preimage the tree to apply the diff to
+ * @param diff the diff to apply
+ * @param options the options for the apply (or null for defaults)
+ */
+GIT_EXTERN(int) git_apply_to_tree(
+	git_index **out,
+	git_repository *repo,
+	git_tree *preimage,
+	git_diff *diff,
+	const git_apply_options *options);
+
+typedef enum {
+	/**
+	 * Apply the patch to the workdir, leaving the index untouched.
+	 * This is the equivalent of `git apply` with no location argument.
+	 */
+	GIT_APPLY_LOCATION_WORKDIR = 0,
+
+	/**
+	 * Apply the patch to the index, leaving the working directory
+	 * untouched.  This is the equivalent of `git apply --cached`.
+	 */
+	GIT_APPLY_LOCATION_INDEX = 1,
+
+	/**
+	 * Apply the patch to both the working directory and the index.
+	 * This is the equivalent of `git apply --index`.
+	 */
+	GIT_APPLY_LOCATION_BOTH = 2,
+} git_apply_location_t;
+
+/**
+ * Apply a `git_diff` to the given repository, making changes directly
+ * in the working directory, the index, or both.
+ *
+ * @param repo the repository to apply to
+ * @param diff the diff to apply
+ * @param location the location to apply (workdir, index or both)
+ * @param options the options for the apply (or null for defaults)
+ */
+GIT_EXTERN(int) git_apply(
+	git_repository *repo,
+	git_diff *diff,
+	git_apply_location_t location,
+	const git_apply_options *options);
+
+/** @} */
+GIT_END_DECL
+#endif
diff --git a/include/git2/errors.h b/include/git2/errors.h
index c2a01de..b0ce45f 100644
--- a/include/git2/errors.h
+++ b/include/git2/errors.h
@@ -57,6 +57,7 @@ typedef enum {
 	GIT_RETRY           = -32,	/**< Internal only */
 	GIT_EMISMATCH       = -33,	/**< Hashsum mismatch in object */
 	GIT_EINDEXDIRTY     = -34,	/**< Unsaved changes in the index would be overwritten */
+	GIT_EAPPLYFAIL      = -35,	/**< Patch application failed */
 } git_error_code;
 
 /**
diff --git a/src/apply.c b/src/apply.c
index 8c7bb6b..614baf7 100644
--- a/src/apply.c
+++ b/src/apply.c
@@ -9,16 +9,23 @@
 
 #include <assert.h>
 
+#include "git2/apply.h"
 #include "git2/patch.h"
 #include "git2/filter.h"
+#include "git2/blob.h"
+#include "git2/index.h"
+#include "git2/checkout.h"
+#include "git2/repository.h"
 #include "array.h"
 #include "patch.h"
 #include "fileops.h"
 #include "delta.h"
 #include "zstream.h"
+#include "reader.h"
+#include "index.h"
 
 #define apply_err(...) \
-	( giterr_set(GITERR_PATCH, __VA_ARGS__), -1 )
+	( giterr_set(GITERR_PATCH, __VA_ARGS__), GIT_EAPPLYFAIL )
 
 typedef struct {
 	/* The lines that we allocate ourself are allocated out of the pool.
@@ -160,15 +167,36 @@ static int update_hunk(
 	return 0;
 }
 
+typedef struct {
+	git_apply_options opts;
+	size_t skipped_new_lines;
+	size_t skipped_old_lines;
+} apply_hunks_ctx;
+
 static int apply_hunk(
 	patch_image *image,
 	git_patch *patch,
-	git_patch_hunk *hunk)
+	git_patch_hunk *hunk,
+	apply_hunks_ctx *ctx)
 {
 	patch_image preimage = PATCH_IMAGE_INIT, postimage = PATCH_IMAGE_INIT;
 	size_t line_num, i;
 	int error = 0;
 
+	if (ctx->opts.hunk_cb) {
+		error = ctx->opts.hunk_cb(&hunk->hunk, ctx->opts.payload);
+
+		if (error) {
+			if (error > 0) {
+				ctx->skipped_new_lines += hunk->hunk.new_lines;
+				ctx->skipped_old_lines += hunk->hunk.old_lines;
+				error = 0;
+			}
+
+			goto done;
+		}
+	}
+
 	for (i = 0; i < hunk->line_count; i++) {
 		size_t linenum = hunk->line_start + i;
 		git_diff_line *line = git_array_get(patch->lines, linenum);
@@ -191,7 +219,14 @@ static int apply_hunk(
 		}
 	}
 
-	line_num = hunk->hunk.new_start ? hunk->hunk.new_start - 1 : 0;
+	if (hunk->hunk.new_start) {
+		line_num = hunk->hunk.new_start -
+			ctx->skipped_new_lines +
+			ctx->skipped_old_lines -
+			1;
+	} else {
+		line_num = 0;
+	}
 
 	if (!find_hunk_linenum(&line_num, image, &preimage, line_num)) {
 		error = apply_err("hunk at line %d did not apply",
@@ -212,7 +247,8 @@ static int apply_hunks(
 	git_buf *out,
 	const char *source,
 	size_t source_len,
-	git_patch *patch)
+	git_patch *patch,
+	apply_hunks_ctx *ctx)
 {
 	git_patch_hunk *hunk;
 	git_diff_line *line;
@@ -224,7 +260,7 @@ static int apply_hunks(
 		goto done;
 
 	git_array_foreach(patch->hunks, i, hunk) {
-		if ((error = apply_hunk(&image, patch, hunk)) < 0)
+		if ((error = apply_hunk(&image, patch, hunk, ctx)) < 0)
 			goto done;
 	}
 
@@ -332,14 +368,19 @@ int git_apply__patch(
 	unsigned int *mode_out,
 	const char *source,
 	size_t source_len,
-	git_patch *patch)
+	git_patch *patch,
+	const git_apply_options *given_opts)
 {
+	apply_hunks_ctx ctx = { GIT_APPLY_OPTIONS_INIT };
 	char *filename = NULL;
 	unsigned int mode = 0;
 	int error = 0;
 
 	assert(contents_out && filename_out && mode_out && (source || !source_len) && patch);
 
+	if (given_opts)
+		memcpy(&ctx.opts, given_opts, sizeof(git_apply_options));
+
 	*filename_out = NULL;
 	*mode_out = 0;
 
@@ -354,7 +395,7 @@ int git_apply__patch(
 	if (patch->delta->flags & GIT_DIFF_FLAG_BINARY)
 		error = apply_binary(contents_out, source, source_len, patch);
 	else if (patch->hunks.size)
-		error = apply_hunks(contents_out, source, source_len, patch);
+		error = apply_hunks(contents_out, source, source_len, patch, &ctx);
 	else
 		error = git_buf_put(contents_out, source, source_len);
 
@@ -376,3 +417,438 @@ done:
 
 	return error;
 }
+
+static int apply_one(
+	git_repository *repo,
+	git_reader *preimage_reader,
+	git_index *preimage,
+	git_reader *postimage_reader,
+	git_index *postimage,
+	git_diff *diff,
+	git_strmap *removed_paths,
+	size_t i,
+	const git_apply_options *opts)
+{
+	git_patch *patch = NULL;
+	git_buf pre_contents = GIT_BUF_INIT, post_contents = GIT_BUF_INIT;
+	const git_diff_delta *delta;
+	char *filename = NULL;
+	unsigned int mode;
+	git_oid pre_id, post_id;
+	git_filemode_t pre_filemode;
+	git_index_entry pre_entry, post_entry;
+	bool skip_preimage = false;
+	size_t pos;
+	int error;
+
+	if ((error = git_patch_from_diff(&patch, diff, i)) < 0)
+		goto done;
+
+	delta = git_patch_get_delta(patch);
+
+	if (opts->delta_cb) {
+		error = opts->delta_cb(delta, opts->payload);
+
+		if (error) {
+			if (error > 0)
+				error = 0;
+
+			goto done;
+		}
+	}
+
+	/*
+	 * Ensure that the file has not been deleted or renamed if we're
+	 * applying a modification delta.
+	 */
+	if (delta->status != GIT_DELTA_RENAMED &&
+	    delta->status != GIT_DELTA_ADDED) {
+		pos = git_strmap_lookup_index(removed_paths, delta->old_file.path);
+		if (git_strmap_valid_index(removed_paths, pos)) {
+			error = apply_err("path '%s' has been renamed or deleted", delta->old_file.path);
+			goto done;
+		}
+	}
+
+	/*
+	 * We may be applying a second delta to an already seen file.  If so,
+	 * use the already modified data in the postimage instead of the
+	 * content from the index or working directory.  (Don't do this in
+	 * the case of a rename, which must be specified before additional
+	 * deltas since we apply deltas to the target filename.)
+	 */
+	if (delta->status != GIT_DELTA_RENAMED) {
+		if ((error = git_reader_read(&pre_contents, &pre_id, &pre_filemode,
+		    postimage_reader, delta->old_file.path)) == 0) {
+			skip_preimage = true;
+		} else if (error == GIT_ENOTFOUND) {
+			giterr_clear();
+			error = 0;
+		} else {
+			goto done;
+		}
+	}
+
+	if (!skip_preimage && delta->status != GIT_DELTA_ADDED) {
+		error = git_reader_read(&pre_contents, &pre_id, &pre_filemode,
+			preimage_reader, delta->old_file.path);
+
+		/* ENOTFOUND means the preimage was not found; apply failed. */
+		if (error == GIT_ENOTFOUND)
+			error = GIT_EAPPLYFAIL;
+
+		/* When applying to BOTH, the index did not match the workdir. */
+		if (error == GIT_READER_MISMATCH)
+			error = apply_err("%s: does not match index", delta->old_file.path);
+
+		if (error < 0)
+			goto done;
+
+		/*
+		 * We need to populate the preimage data structure with the
+		 * contents that we are using as the preimage for this file.
+		 * This allows us to apply patches to files that have been
+		 * modified in the working directory.  During checkout,
+		 * we will use this expected preimage as the baseline, and
+		 * limit checkout to only the paths affected by patch
+		 * application.  (Without this, we would fail to write the
+		 * postimage contents to any file that had been modified
+		 * from HEAD on-disk, even if the patch application succeeded.)
+		 * Use the contents from the delta where available - some
+		 * fields may not be available, like the old file mode (eg in
+		 * an exact rename situation) so trust the patch parsing to
+		 * validate and use the preimage data in that case.
+		 */
+		if (preimage) {
+			memset(&pre_entry, 0, sizeof(git_index_entry));
+			pre_entry.path = delta->old_file.path;
+			pre_entry.mode = delta->old_file.mode ? delta->old_file.mode : pre_filemode;
+			git_oid_cpy(&pre_entry.id, &pre_id);
+
+			if ((error = git_index_add(preimage, &pre_entry)) < 0)
+				goto done;
+		}
+	}
+
+	if (delta->status != GIT_DELTA_DELETED) {
+		if ((error = git_apply__patch(&post_contents, &filename, &mode,
+				pre_contents.ptr, pre_contents.size, patch, opts)) < 0 ||
+			(error = git_blob_create_frombuffer(&post_id, repo,
+				post_contents.ptr, post_contents.size)) < 0)
+			goto done;
+
+		memset(&post_entry, 0, sizeof(git_index_entry));
+		post_entry.path = filename;
+		post_entry.mode = mode;
+		git_oid_cpy(&post_entry.id, &post_id);
+
+		if ((error = git_index_add(postimage, &post_entry)) < 0)
+			goto done;
+	}
+
+	if (delta->status == GIT_DELTA_RENAMED ||
+	    delta->status == GIT_DELTA_DELETED)
+		git_strmap_insert(removed_paths, delta->old_file.path, (char *)delta->old_file.path, &error);
+
+	if (delta->status == GIT_DELTA_RENAMED ||
+	    delta->status == GIT_DELTA_ADDED)
+		git_strmap_delete(removed_paths, delta->new_file.path);
+
+done:
+	git_buf_dispose(&pre_contents);
+	git_buf_dispose(&post_contents);
+	git__free(filename);
+	git_patch_free(patch);
+
+	return error;
+}
+
+static int apply_deltas(
+	git_repository *repo,
+	git_reader *pre_reader,
+	git_index *preimage,
+	git_reader *post_reader,
+	git_index *postimage,
+	git_diff *diff,
+	const git_apply_options *opts)
+{
+	git_strmap *removed_paths;
+	size_t i;
+	int error;
+
+	if (git_strmap_alloc(&removed_paths) < 0)
+		return -1;
+
+	for (i = 0; i < git_diff_num_deltas(diff); i++) {
+		if ((error = apply_one(repo, pre_reader, preimage, post_reader, postimage, diff, removed_paths, i, opts)) < 0)
+			goto done;
+	}
+
+done:
+	git_strmap_free(removed_paths);
+	return error;
+}
+
+int git_apply_to_tree(
+	git_index **out,
+	git_repository *repo,
+	git_tree *preimage,
+	git_diff *diff,
+	const git_apply_options *given_opts)
+{
+	git_index *postimage = NULL;
+	git_reader *pre_reader = NULL, *post_reader = NULL;
+	git_apply_options opts = GIT_APPLY_OPTIONS_INIT;
+	const git_diff_delta *delta;
+	size_t i;
+	int error = 0;
+
+	assert(out && repo && preimage && diff);
+
+	*out = NULL;
+
+	if (given_opts)
+		memcpy(&opts, given_opts, sizeof(git_apply_options));
+
+	if ((error = git_reader_for_tree(&pre_reader, preimage)) < 0)
+		goto done;
+
+	/*
+	 * put the current tree into the postimage as-is - the diff will
+	 * replace any entries contained therein
+	 */
+	if ((error = git_index_new(&postimage)) < 0 ||
+		(error = git_index_read_tree(postimage, preimage)) < 0 ||
+		(error = git_reader_for_index(&post_reader, repo, postimage)) < 0)
+		goto done;
+
+	/*
+	 * Remove the old paths from the index before applying diffs -
+	 * we need to do a full pass to remove them before adding deltas,
+	 * in order to handle rename situations.
+	 */
+	for (i = 0; i < git_diff_num_deltas(diff); i++) {
+		delta = git_diff_get_delta(diff, i);
+
+		if ((error = git_index_remove(postimage,
+				delta->old_file.path, 0)) < 0)
+			goto done;
+	}
+
+	if ((error = apply_deltas(repo, pre_reader, NULL, post_reader, postimage, diff, &opts)) < 0)
+		goto done;
+
+	*out = postimage;
+
+done:
+	if (error < 0)
+		git_index_free(postimage);
+
+	git_reader_free(pre_reader);
+	git_reader_free(post_reader);
+
+	return error;
+}
+
+static int git_apply__to_workdir(
+	git_repository *repo,
+	git_diff *diff,
+	git_index *preimage,
+	git_index *postimage,
+	git_apply_location_t location,
+	git_apply_options *opts)
+{
+	git_vector paths = GIT_VECTOR_INIT;
+	git_checkout_options checkout_opts = GIT_CHECKOUT_OPTIONS_INIT;
+	const git_diff_delta *delta;
+	size_t i;
+	int error;
+
+	GIT_UNUSED(opts);
+
+	/*
+	 * Limit checkout to the paths affected by the diff; this ensures
+	 * that other modifications in the working directory are unaffected.
+	 */
+	if ((error = git_vector_init(&paths, git_diff_num_deltas(diff), NULL)) < 0)
+		goto done;
+
+	for (i = 0; i < git_diff_num_deltas(diff); i++) {
+		delta = git_diff_get_delta(diff, i);
+
+		if ((error = git_vector_insert(&paths, (void *)delta->old_file.path)) < 0)
+			goto done;
+
+		if (strcmp(delta->old_file.path, delta->new_file.path) &&
+		    (error = git_vector_insert(&paths, (void *)delta->new_file.path)) < 0)
+			goto done;
+	}
+
+	checkout_opts.checkout_strategy |= GIT_CHECKOUT_SAFE;
+	checkout_opts.checkout_strategy |= GIT_CHECKOUT_DISABLE_PATHSPEC_MATCH;
+	checkout_opts.checkout_strategy |= GIT_CHECKOUT_DONT_WRITE_INDEX;
+
+	if (location == GIT_APPLY_LOCATION_WORKDIR)
+		checkout_opts.checkout_strategy |= GIT_CHECKOUT_DONT_UPDATE_INDEX;
+
+	checkout_opts.paths.strings = (char **)paths.contents;
+	checkout_opts.paths.count = paths.length;
+
+	checkout_opts.baseline_index = preimage;
+
+	error = git_checkout_index(repo, postimage, &checkout_opts);
+
+done:
+	git_vector_free(&paths);
+	return error;
+}
+
+static int git_apply__to_index(
+	git_repository *repo,
+	git_diff *diff,
+	git_index *preimage,
+	git_index *postimage,
+	git_apply_options *opts)
+{
+	git_index *index = NULL;
+	const git_diff_delta *delta;
+	const git_index_entry *entry;
+	size_t i;
+	int error;
+
+	GIT_UNUSED(preimage);
+	GIT_UNUSED(opts);
+
+	if ((error = git_repository_index(&index, repo)) < 0)
+		goto done;
+
+	/* Remove deleted (or renamed) paths from the index. */
+	for (i = 0; i < git_diff_num_deltas(diff); i++) {
+		delta = git_diff_get_delta(diff, i);
+
+		if (delta->status == GIT_DELTA_DELETED ||
+		    delta->status == GIT_DELTA_RENAMED) {
+			if ((error = git_index_remove(index, delta->old_file.path, 0)) < 0)
+				goto done;
+		}
+	}
+
+	/* Then add the changes back to the index. */
+	for (i = 0; i < git_index_entrycount(postimage); i++) {
+		entry = git_index_get_byindex(postimage, i);
+
+		if ((error = git_index_add(index, entry)) < 0)
+			goto done;
+	}
+
+done:
+	git_index_free(index);
+	return error;
+}
+
+/*
+ * Handle the three application options ("locations"):
+ *
+ * GIT_APPLY_LOCATION_WORKDIR: the default, emulates `git apply`.
+ * Applies the diff only to the workdir items and ignores the index
+ * entirely.
+ *
+ * GIT_APPLY_LOCATION_INDEX: emulates `git apply --cached`.
+ * Applies the diff only to the index items and ignores the workdir
+ * completely.
+ *
+ * GIT_APPLY_LOCATION_BOTH: emulates `git apply --index`.
+ * Applies the diff to both the index items and the working directory
+ * items.
+ */
+
+int git_apply(
+	git_repository *repo,
+	git_diff *diff,
+	git_apply_location_t location,
+	const git_apply_options *given_opts)
+{
+	git_indexwriter indexwriter = GIT_INDEXWRITER_INIT;
+	git_index *index = NULL, *preimage = NULL, *postimage = NULL;
+	git_reader *pre_reader = NULL, *post_reader = NULL;
+	git_apply_options opts = GIT_APPLY_OPTIONS_INIT;
+	int error = GIT_EINVALID;
+
+	assert(repo && diff);
+
+	GITERR_CHECK_VERSION(
+		given_opts, GIT_APPLY_OPTIONS_VERSION, "git_apply_options");
+
+	if (given_opts)
+		memcpy(&opts, given_opts, sizeof(git_apply_options));
+
+	/*
+	 * by default, we apply a patch directly to the working directory;
+	 * in `--cached` or `--index` mode, we apply to the contents already
+	 * in the index.
+	 */
+	switch (location) {
+	case GIT_APPLY_LOCATION_BOTH:
+		error = git_reader_for_workdir(&pre_reader, repo, true);
+		break;
+	case GIT_APPLY_LOCATION_INDEX:
+		error = git_reader_for_index(&pre_reader, repo, NULL);
+		break;
+	case GIT_APPLY_LOCATION_WORKDIR:
+		error = git_reader_for_workdir(&pre_reader, repo, false);
+		break;
+	default:
+		assert(false);
+	}
+
+	if (error < 0)
+		goto done;
+
+	/*
+	 * Build the preimage and postimage (differences).  Note that
+	 * this is not the complete preimage or postimage, it only
+	 * contains the files affected by the patch.  We want to avoid
+	 * having the full repo index, so we will limit our checkout
+	 * to only write these files that were affected by the diff.
+	 */
+	if ((error = git_index_new(&preimage)) < 0 ||
+	    (error = git_index_new(&postimage)) < 0 ||
+	    (error = git_reader_for_index(&post_reader, repo, postimage)) < 0)
+		goto done;
+
+	if ((error = git_repository_index(&index, repo)) < 0 ||
+	    (error = git_indexwriter_init(&indexwriter, index)) < 0)
+		goto done;
+
+	if ((error = apply_deltas(repo, pre_reader, preimage, post_reader, postimage, diff, &opts)) < 0)
+		goto done;
+
+	switch (location) {
+	case GIT_APPLY_LOCATION_BOTH:
+		error = git_apply__to_workdir(repo, diff, preimage, postimage, location, &opts);
+		break;
+	case GIT_APPLY_LOCATION_INDEX:
+		error = git_apply__to_index(repo, diff, preimage, postimage, &opts);
+		break;
+	case GIT_APPLY_LOCATION_WORKDIR:
+		error = git_apply__to_workdir(repo, diff, preimage, postimage, location, &opts);
+		break;
+	default:
+		assert(false);
+	}
+
+	if (error < 0)
+		goto done;
+
+	error = git_indexwriter_commit(&indexwriter);
+
+done:
+	git_indexwriter_cleanup(&indexwriter);
+	git_index_free(postimage);
+	git_index_free(preimage);
+	git_index_free(index);
+	git_reader_free(pre_reader);
+	git_reader_free(post_reader);
+
+	return error;
+}
diff --git a/src/apply.h b/src/apply.h
index b29460c..11ec756 100644
--- a/src/apply.h
+++ b/src/apply.h
@@ -10,6 +10,7 @@
 #include "common.h"
 
 #include "git2/patch.h"
+#include "git2/apply.h"
 #include "buffer.h"
 
 extern int git_apply__patch(
@@ -18,6 +19,7 @@ extern int git_apply__patch(
 	unsigned int *mode,
 	const char *source,
 	size_t source_len,
-	git_patch *patch);
+	git_patch *patch,
+	const git_apply_options *opts);
 
 #endif
diff --git a/src/iterator.c b/src/iterator.c
index 6e7300a..40f6759 100644
--- a/src/iterator.c
+++ b/src/iterator.c
@@ -1015,6 +1015,7 @@ typedef struct {
 	struct stat st;
 	size_t path_len;
 	iterator_pathlist_search_t match;
+	git_oid id;
 	char path[GIT_FLEX_ARRAY];
 } filesystem_iterator_entry;
 
@@ -1265,7 +1266,32 @@ GIT_INLINE(bool) filesystem_iterator_is_dot_git(
 	return (len == 4 || path[len - 5] == '/');
 }
 
-static filesystem_iterator_entry *filesystem_iterator_entry_init(
+static int filesystem_iterator_entry_hash(
+	filesystem_iterator *iter,
+	filesystem_iterator_entry *entry)
+{
+	git_buf fullpath = GIT_BUF_INIT;
+	int error;
+
+	if (S_ISDIR(entry->st.st_mode)) {
+		memset(&entry->id, 0, GIT_OID_RAWSZ);
+		return 0;
+	}
+
+	if (iter->base.type == GIT_ITERATOR_TYPE_WORKDIR)
+		return git_repository_hashfile(&entry->id,
+			iter->base.repo, entry->path, GIT_OBJ_BLOB, NULL);
+
+	if (!(error = git_buf_joinpath(&fullpath, iter->root, entry->path)))
+		error = git_odb_hashfile(&entry->id, fullpath.ptr, GIT_OBJ_BLOB);
+
+	git_buf_dispose(&fullpath);
+	return error;
+}
+
+static int filesystem_iterator_entry_init(
+	filesystem_iterator_entry **out,
+	filesystem_iterator *iter,
 	filesystem_iterator_frame *frame,
 	const char *path,
 	size_t path_len,
@@ -1274,15 +1300,19 @@ static filesystem_iterator_entry *filesystem_iterator_entry_init(
 {
 	filesystem_iterator_entry *entry;
 	size_t entry_size;
+	int error = 0;
+
+	*out = NULL;
 
 	/* Make sure to append two bytes, one for the path's null
 	 * termination, one for a possible trailing '/' for folders.
 	 */
-	if (GIT_ADD_SIZET_OVERFLOW(&entry_size,
-			sizeof(filesystem_iterator_entry), path_len) ||
-		GIT_ADD_SIZET_OVERFLOW(&entry_size, entry_size, 2) ||
-		(entry = git_pool_malloc(&frame->entry_pool, entry_size)) == NULL)
-		return NULL;
+	GITERR_CHECK_ALLOC_ADD(&entry_size,
+		sizeof(filesystem_iterator_entry), path_len);
+	GITERR_CHECK_ALLOC_ADD(&entry_size, entry_size, 2);
+
+	entry = git_pool_malloc(&frame->entry_pool, entry_size);
+	GITERR_CHECK_ALLOC(entry);
 
 	entry->path_len = path_len;
 	entry->match = pathlist_match;
@@ -1295,7 +1325,13 @@ static filesystem_iterator_entry *filesystem_iterator_entry_init(
 
 	entry->path[entry->path_len] = '\0';
 
-	return entry;
+	if (iter->base.flags & GIT_ITERATOR_INCLUDE_HASH)
+		error = filesystem_iterator_entry_hash(iter, entry);
+
+	if (!error)
+		*out = entry;
+
+	return error;
 }
 
 static int filesystem_iterator_frame_push(
@@ -1418,9 +1454,9 @@ static int filesystem_iterator_frame_push(
 		else if (dir_expected)
 			continue;
 
-		entry = filesystem_iterator_entry_init(new_frame,
-			path, path_len, &statbuf, pathlist_match);
-		GITERR_CHECK_ALLOC(entry);
+		if ((error = filesystem_iterator_entry_init(&entry,
+			iter, new_frame, path, path_len, &statbuf, pathlist_match)) < 0)
+			goto done;
 
 		git_vector_insert(&new_frame->entries, entry);
 	}
@@ -1460,7 +1496,7 @@ static void filesystem_iterator_set_current(
 	iter->entry.ctime.seconds = entry->st.st_ctime;
 	iter->entry.mtime.seconds = entry->st.st_mtime;
 
-#if defined(GIT_USE_NSEC)	
+#if defined(GIT_USE_NSEC)
 	iter->entry.ctime.nanoseconds = entry->st.st_ctime_nsec;
 	iter->entry.mtime.nanoseconds = entry->st.st_mtime_nsec;
 #else
@@ -1475,6 +1511,9 @@ static void filesystem_iterator_set_current(
 	iter->entry.gid = entry->st.st_gid;
 	iter->entry.file_size = entry->st.st_size;
 
+	if (iter->base.flags & GIT_ITERATOR_INCLUDE_HASH)
+		git_oid_cpy(&iter->entry.id, &entry->id);
+
 	iter->entry.path = entry->path;
 
 	iter->current_is_ignored = GIT_IGNORE_UNCHECKED;
@@ -2259,6 +2298,35 @@ void git_iterator_free(git_iterator *iter)
 	git__free(iter);
 }
 
+int git_iterator_foreach(
+	git_iterator *iterator,
+	git_iterator_foreach_cb cb,
+	void *data)
+{
+	const git_index_entry *iterator_item;
+	int error = 0;
+
+	if ((error = git_iterator_current(&iterator_item, iterator)) < 0)
+		goto done;
+
+	if ((error = cb(iterator_item, data)) != 0)
+		goto done;
+
+	while (true) {
+		if ((error = git_iterator_advance(&iterator_item, iterator)) < 0)
+			goto done;
+
+		if ((error = cb(iterator_item, data)) != 0)
+			goto done;
+	}
+
+done:
+	if (error == GIT_ITEROVER)
+		error = 0;
+
+	return error;
+}
+
 int git_iterator_walk(
 	git_iterator **iterators,
 	size_t cnt,
diff --git a/src/iterator.h b/src/iterator.h
index a6497d8..bbe357f 100644
--- a/src/iterator.h
+++ b/src/iterator.h
@@ -41,6 +41,8 @@ typedef enum {
 	GIT_ITERATOR_INCLUDE_CONFLICTS = (1u << 6),
 	/** descend into symlinked directories */
 	GIT_ITERATOR_DESCEND_SYMLINKS = (1u << 7),
+	/** hash files in workdir or filesystem iterators */
+	GIT_ITERATOR_INCLUDE_HASH = (1u << 8),
 } git_iterator_flag_t;
 
 typedef enum {
@@ -289,6 +291,19 @@ extern int git_iterator_current_workdir_path(
  */
 extern git_index *git_iterator_index(git_iterator *iter);
 
+typedef int (*git_iterator_foreach_cb)(
+	const git_index_entry *entry,
+	void *data);
+
+/**
+ * Walk the given iterator and invoke the callback for each path
+ * contained in the iterator.
+ */
+extern int git_iterator_foreach(
+	git_iterator *iterator,
+	git_iterator_foreach_cb cb,
+	void *data);
+
 typedef int (*git_iterator_walk_cb)(
 	const git_index_entry **entries,
 	void *data);
diff --git a/src/reader.c b/src/reader.c
new file mode 100644
index 0000000..9375ff3
--- /dev/null
+++ b/src/reader.c
@@ -0,0 +1,259 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "reader.h"
+
+#include "fileops.h"
+#include "blob.h"
+
+#include "git2/tree.h"
+#include "git2/blob.h"
+#include "git2/index.h"
+#include "git2/repository.h"
+
+/* tree reader */
+
+typedef struct {
+	git_reader reader;
+	git_tree *tree;
+} tree_reader;
+
+static int tree_reader_read(
+	git_buf *out,
+	git_oid *out_id,
+	git_filemode_t *out_filemode,
+	git_reader *_reader,
+	const char *filename)
+{
+	tree_reader *reader = (tree_reader *)_reader;
+	git_tree_entry *tree_entry = NULL;
+	git_blob *blob = NULL;
+	int error;
+
+	if ((error = git_tree_entry_bypath(&tree_entry, reader->tree, filename)) < 0 ||
+	    (error = git_blob_lookup(&blob, git_tree_owner(reader->tree), git_tree_entry_id(tree_entry))) < 0 ||
+	    (error = git_buf_set(out, git_blob_rawcontent(blob), git_blob_rawsize(blob))) < 0)
+		goto done;
+
+	if (out_id)
+		git_oid_cpy(out_id, git_tree_entry_id(tree_entry));
+
+	if (out_filemode)
+		*out_filemode = git_tree_entry_filemode(tree_entry);
+
+done:
+	git_blob_free(blob);
+	git_tree_entry_free(tree_entry);
+	return error;
+}
+
+int git_reader_for_tree(git_reader **out, git_tree *tree)
+{
+	tree_reader *reader;
+
+	assert(out && tree);
+
+	reader = git__calloc(1, sizeof(tree_reader));
+	GITERR_CHECK_ALLOC(reader);
+
+	reader->reader.read = tree_reader_read;
+	reader->tree = tree;
+
+	*out = (git_reader *)reader;
+	return 0;
+}
+
+/* workdir reader */
+
+typedef struct {
+	git_reader reader;
+	git_repository *repo;
+	git_index *index;
+} workdir_reader;
+
+static int workdir_reader_read(
+	git_buf *out,
+	git_oid *out_id,
+	git_filemode_t *out_filemode,
+	git_reader *_reader,
+	const char *filename)
+{
+	workdir_reader *reader = (workdir_reader *)_reader;
+	git_buf path = GIT_BUF_INIT;
+	struct stat st;
+	git_filemode_t filemode;
+	git_filter_list *filters = NULL;
+	const git_index_entry *idx_entry;
+	git_oid id;
+	int error;
+
+	if ((error = git_buf_joinpath(&path,
+		git_repository_workdir(reader->repo), filename)) < 0)
+		goto done;
+
+	if ((error = p_lstat(path.ptr, &st)) < 0) {
+		if (error == -1 && errno == ENOENT)
+			error = GIT_ENOTFOUND;
+
+		giterr_set(GITERR_OS, "could not stat '%s'", path.ptr);
+		goto done;
+	}
+
+	filemode = git_futils_canonical_mode(st.st_mode);
+
+	/*
+	 * Patch application - for example - uses the filtered version of
+	 * the working directory data to match git.  So we will run the
+	 * workdir -> ODB filter on the contents in this workdir reader.
+	 */
+	if ((error = git_filter_list_load(&filters, reader->repo, NULL, filename,
+		GIT_FILTER_TO_ODB, GIT_FILTER_DEFAULT)) < 0)
+		goto done;
+
+	if ((error = git_filter_list_apply_to_file(out,
+	    filters, reader->repo, path.ptr)) < 0)
+		goto done;
+
+	if (out_id || reader->index) {
+		if ((error = git_odb_hash(&id, out->ptr, out->size, GIT_OBJ_BLOB)) < 0)
+			goto done;
+	}
+
+	if (reader->index) {
+		if (!(idx_entry = git_index_get_bypath(reader->index, filename, 0)) ||
+		    filemode != idx_entry->mode ||
+		    !git_oid_equal(&id, &idx_entry->id)) {
+			error = GIT_READER_MISMATCH;
+			goto done;
+		}
+	}
+
+	if (out_id)
+		git_oid_cpy(out_id, &id);
+
+	if (out_filemode)
+		*out_filemode = filemode;
+
+done:
+	git_filter_list_free(filters);
+	git_buf_dispose(&path);
+	return error;
+}
+
+int git_reader_for_workdir(
+	git_reader **out,
+	git_repository *repo,
+	bool validate_index)
+{
+	workdir_reader *reader;
+	int error;
+
+	assert(out && repo);
+
+	reader = git__calloc(1, sizeof(workdir_reader));
+	GITERR_CHECK_ALLOC(reader);
+
+	reader->reader.read = workdir_reader_read;
+	reader->repo = repo;
+
+	if (validate_index &&
+	    (error = git_repository_index__weakptr(&reader->index, repo)) < 0) {
+		git__free(reader);
+		return error;
+	}
+
+	*out = (git_reader *)reader;
+	return 0;
+}
+
+/* index reader */
+
+typedef struct {
+	git_reader reader;
+	git_repository *repo;
+	git_index *index;
+} index_reader;
+
+static int index_reader_read(
+	git_buf *out,
+	git_oid *out_id,
+	git_filemode_t *out_filemode,
+	git_reader *_reader,
+	const char *filename)
+{
+	index_reader *reader = (index_reader *)_reader;
+	const git_index_entry *entry;
+	git_blob *blob;
+	int error;
+
+	if ((entry = git_index_get_bypath(reader->index, filename, 0)) == NULL)
+		return GIT_ENOTFOUND;
+
+	if ((error = git_blob_lookup(&blob, reader->repo, &entry->id)) < 0)
+		goto done;
+
+	if (out_id)
+		git_oid_cpy(out_id, &entry->id);
+
+	if (out_filemode)
+		*out_filemode = entry->mode;
+
+	error = git_blob__getbuf(out, blob);
+
+done:
+	git_blob_free(blob);
+	return error;
+}
+
+int git_reader_for_index(
+	git_reader **out,
+	git_repository *repo,
+	git_index *index)
+{
+	index_reader *reader;
+	int error;
+
+	assert(out && repo);
+
+	reader = git__calloc(1, sizeof(index_reader));
+	GITERR_CHECK_ALLOC(reader);
+
+	reader->reader.read = index_reader_read;
+	reader->repo = repo;
+
+	if (index) {
+		reader->index = index;
+	} else if ((error = git_repository_index__weakptr(&reader->index, repo)) < 0) {
+		git__free(reader);
+		return error;
+	}
+
+	*out = (git_reader *)reader;
+	return 0;
+}
+
+/* generic */
+
+int git_reader_read(
+	git_buf *out,
+	git_oid *out_id,
+	git_filemode_t *out_filemode,
+	git_reader *reader,
+	const char *filename)
+{
+	assert(out && reader && filename);
+
+	return reader->read(out, out_id, out_filemode, reader, filename);
+}
+
+void git_reader_free(git_reader *reader)
+{
+	if (!reader)
+		return;
+
+	git__free(reader);
+}
diff --git a/src/reader.h b/src/reader.h
new file mode 100644
index 0000000..18a6a11
--- /dev/null
+++ b/src/reader.h
@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_reader_h__
+#define INCLUDE_reader_h__
+
+#include "common.h"
+
+/* Returned when the workdir does not match the index */
+#define GIT_READER_MISMATCH	1
+
+typedef struct git_reader git_reader;
+
+/*
+ * The `git_reader` structure is a generic interface for reading the
+ * contents of a file by its name, and implementations are provided
+ * for reading out of a tree, the index, and the working directory.
+ *
+ * Note that the reader implementation is meant to have a short
+ * lifecycle and does not increase the refcount of the object that
+ * it's reading.  Callers should ensure that they do not use a
+ * reader after disposing the underlying object that it reads.
+ */
+struct git_reader {
+	int (*read)(git_buf *out, git_oid *out_oid, git_filemode_t *mode, git_reader *reader, const char *filename);
+};
+
+/**
+ * Create a `git_reader` that will allow random access to the given
+ * tree.  Paths requested via `git_reader_read` will be rooted at this
+ * tree, callers are not expected to recurse through tree lookups.  Thus,
+ * you can request to read `/src/foo.c` and the tree provided to this
+ * function will be searched to find another tree named `src`, which
+ * will then be opened to find `foo.c`.
+ *
+ * @param out The reader for the given tree
+ * @param tree The tree object to read
+ * @return 0 on success, or an error code < 0
+ */
+extern int git_reader_for_tree(
+	git_reader **out,
+	git_tree *tree);
+
+/**
+ * Create a `git_reader` that will allow random access to the given
+ * index, or the repository's index.
+ *
+ * @param out The reader for the given index
+ * @param repo The repository containing the index
+ * @param index The index to read, or NULL to use the repository's index
+ * @return 0 on success, or an error code < 0
+ */
+extern int git_reader_for_index(
+	git_reader **out,
+	git_repository *repo,
+	git_index *index);
+
+/**
+ * Create a `git_reader` that will allow random access to the given
+ * repository's working directory.  Note that the contents are read
+ * in repository format, meaning any workdir -> odb filters are
+ * applied.
+ *
+ * If `validate_index` is set to true, reads of files will hash the
+ * on-disk contents and ensure that the resulting object ID matches
+ * the repository's index.  This ensures that the working directory
+ * is unmodified from the index contents.
+ *
+ * @param out The reader for the given working directory
+ * @param repo The repository containing the working directory
+ * @param validate_index If true, the working directory contents will
+ *        be compared to the index contents during read to ensure that
+ *        the working directory is unmodified.
+ * @return 0 on success, or an error code < 0
+ */
+extern int git_reader_for_workdir(
+	git_reader **out,
+	git_repository *repo,
+	bool validate_index);
+
+/**
+ * Read the given filename from the reader and populate the given buffer
+ * with the contents and the given oid with the object ID.
+ *
+ * @param out The buffer to populate with the file contents
+ * @param out_id The oid to populate with the object ID
+ * @param reader The reader to read
+ * @param filename The filename to read from the reader
+ */
+extern int git_reader_read(
+	git_buf *out,
+	git_oid *out_id,
+	git_filemode_t *out_filemode,
+	git_reader *reader,
+	const char *filename);
+
+/**
+ * Free the given reader and any associated objects.
+ *
+ * @param reader The reader to free
+ */
+extern void git_reader_free(git_reader *reader);
+
+#endif
diff --git a/tests/apply/apply_helpers.h b/tests/apply/apply_helpers.h
new file mode 100644
index 0000000..8156335
--- /dev/null
+++ b/tests/apply/apply_helpers.h
@@ -0,0 +1,587 @@
+#include "../merge/merge_helpers.h"
+
+#define TEST_REPO_PATH "merge-recursive"
+
+#define DIFF_MODIFY_TWO_FILES \
+	"diff --git a/asparagus.txt b/asparagus.txt\n" \
+	"index f516580..ffb36e5 100644\n" \
+	"--- a/asparagus.txt\n" \
+	"+++ b/asparagus.txt\n" \
+	"@@ -1 +1 @@\n" \
+	"-ASPARAGUS SOUP!\n" \
+	"+ASPARAGUS SOUP.\n" \
+	"diff --git a/veal.txt b/veal.txt\n" \
+	"index 94d2c01..a7b0665 100644\n" \
+	"--- a/veal.txt\n" \
+	"+++ b/veal.txt\n" \
+	"@@ -1 +1 @@\n" \
+	"-VEAL SOUP!\n" \
+	"+VEAL SOUP.\n" \
+	"@@ -7 +7 @@ occasionally, then put into it a shin of veal, let it boil two hours\n" \
+	"-longer. take out the slices of ham, and skim off the grease if any\n" \
+	"+longer; take out the slices of ham, and skim off the grease if any\n"
+
+#define DIFF_DELETE_FILE \
+	"diff --git a/gravy.txt b/gravy.txt\n" \
+	"deleted file mode 100644\n" \
+	"index c4e6cca..0000000\n" \
+	"--- a/gravy.txt\n" \
+	"+++ /dev/null\n" \
+	"@@ -1,8 +0,0 @@\n" \
+	"-GRAVY SOUP.\n" \
+	"-\n" \
+	"-Get eight pounds of coarse lean beef--wash it clean and lay it in your\n" \
+	"-pot, put in the same ingredients as for the shin soup, with the same\n" \
+	"-quantity of water, and follow the process directed for that. Strain the\n" \
+	"-soup through a sieve, and serve it up clear, with nothing more than\n" \
+	"-toasted bread in it; two table-spoonsful of mushroom catsup will add a\n" \
+	"-fine flavour to the soup.\n"
+
+#define DIFF_ADD_FILE \
+	"diff --git a/newfile.txt b/newfile.txt\n" \
+	"new file mode 100644\n" \
+	"index 0000000..6370543\n" \
+	"--- /dev/null\n" \
+	"+++ b/newfile.txt\n" \
+	"@@ -0,0 +1,2 @@\n" \
+	"+This is a new file!\n" \
+	"+Added by a patch.\n"
+
+#define DIFF_EXECUTABLE_FILE \
+	"diff --git a/beef.txt b/beef.txt\n" \
+	"old mode 100644\n" \
+	"new mode 100755\n"
+
+#define DIFF_MANY_CHANGES_ONE \
+	"diff --git a/veal.txt b/veal.txt\n" \
+	"index 94d2c01..c9d7d5d 100644\n" \
+	"--- a/veal.txt\n" \
+	"+++ b/veal.txt\n" \
+	"@@ -1,2 +1,2 @@\n" \
+	"-VEAL SOUP!\n" \
+	"+VEAL SOUP\n" \
+	" \n" \
+	"@@ -4,3 +4,2 @@\n" \
+	" spoonful of black pepper pounded, and two of salt, with two or three\n" \
+	"-slices of lean ham; let it boil steadily two hours; skim it\n" \
+	" occasionally, then put into it a shin of veal, let it boil two hours\n" \
+	"@@ -8,3 +7,3 @@\n" \
+	" should rise, take a gill of good cream, mix with it two table-spoonsful\n" \
+	"-of flour very nicely, and the yelks of two eggs beaten well, strain this\n" \
+	"+OF FLOUR very nicely, and the yelks of two eggs beaten well, strain this\n" \
+	" mixture, and add some chopped parsley; pour some soup on by degrees,\n" \
+	"@@ -12,2 +11,3 @@\n" \
+	" boiled two or three minutes to take off the raw taste of the eggs. If\n" \
+	"+Inserted line.\n" \
+	" the cream be not perfectly sweet, and the eggs quite new, the thickening\n" \
+	"@@ -15,3 +15,3 @@\n" \
+	" in, first taking off their skins, by letting them stand a few minutes in\n" \
+	"-hot water, when they may be easily peeled. When made in this way you\n" \
+	"+Changed line.\n" \
+	" must thicken it with the flour only. Any part of the veal may be used,\n"
+
+#define DIFF_MANY_CHANGES_TWO \
+	"diff --git a/veal.txt b/veal.txt\n" \
+	"index 94d2c01..6b943d6 100644\n" \
+	"--- a/veal.txt\n" \
+	"+++ b/veal.txt\n" \
+	"@@ -1,2 +1,2 @@\n" \
+	"-VEAL SOUP!\n" \
+	"+VEAL SOUP!!!\n" \
+	" \n" \
+	"@@ -4,3 +4,2 @@\n" \
+	" spoonful of black pepper pounded, and two of salt, with two or three\n" \
+	"-slices of lean ham; let it boil steadily two hours; skim it\n" \
+	" occasionally, then put into it a shin of veal, let it boil two hours\n" \
+	"@@ -8,3 +7,3 @@\n" \
+	" should rise, take a gill of good cream, mix with it two table-spoonsful\n" \
+	"-of flour very nicely, and the yelks of two eggs beaten well, strain this\n" \
+	"+of flour very nicely, AND the yelks of two eggs beaten well, strain this\n" \
+	" mixture, and add some chopped parsley; pour some soup on by degrees,\n" \
+	"@@ -12,2 +11,3 @@\n" \
+	" boiled two or three minutes to take off the raw taste of the eggs. If\n" \
+	"+New line.\n" \
+	" the cream be not perfectly sweet, and the eggs quite new, the thickening\n" \
+	"@@ -15,4 +15,5 @@\n" \
+	" in, first taking off their skins, by letting them stand a few minutes in\n" \
+	"-hot water, when they may be easily peeled. When made in this way you\n" \
+	"-must thicken it with the flour only. Any part of the veal may be used,\n" \
+	"-but the shin or knuckle is the nicest.\n" \
+	"+HOT water, when they may be easily peeled. When made in this way you\n" \
+	"+must THICKEN it with the flour only. Any part of the veal may be used,\n" \
+	"+but the shin OR knuckle is the nicest.\n" \
+	"+Another new line.\n" \
+
+#define DIFF_RENAME_FILE \
+	"diff --git a/beef.txt b/notbeef.txt\n" \
+	"similarity index 100%\n" \
+	"rename from beef.txt\n" \
+	"rename to notbeef.txt\n"
+
+#define DIFF_RENAME_AND_MODIFY_FILE \
+	"diff --git a/beef.txt b/notbeef.txt\n" \
+	"similarity index 97%\n" \
+	"rename from beef.txt\n" \
+	"rename to notbeef.txt\n" \
+	"index 68f6182..6fa1014 100644\n" \
+	"--- a/beef.txt\n" \
+	"+++ b/notbeef.txt\n" \
+	"@@ -1,4 +1,4 @@\n" \
+	"-BEEF SOUP.\n" \
+	"+THIS IS NOT BEEF SOUP, IT HAS A NEW NAME.\n" \
+	"\n" \
+	" Take the hind shin of beef, cut off all the flesh off the leg-bone,\n" \
+	" which must be taken away entirely, or the soup will be greasy. Wash the\n"
+
+#define DIFF_RENAME_A_TO_B_TO_C \
+	"diff --git a/asparagus.txt b/asparagus.txt\n" \
+	"deleted file mode 100644\n" \
+	"index f516580..0000000\n" \
+	"--- a/asparagus.txt\n" \
+	"+++ /dev/null\n" \
+	"@@ -1,10 +0,0 @@\n" \
+	"-ASPARAGUS SOUP!\n" \
+	"-\n" \
+	"-Take four large bunches of asparagus, scrape it nicely, cut off one inch\n" \
+	"-of the tops, and lay them in water, chop the stalks and put them on the\n" \
+	"-fire with a piece of bacon, a large onion cut up, and pepper and salt;\n" \
+	"-add two quarts of water, boil them till the stalks are quite soft, then\n" \
+	"-pulp them through a sieve, and strain the water to it, which must be put\n" \
+	"-back in the pot; put into it a chicken cut up, with the tops of\n" \
+	"-asparagus which had been laid by, boil it until these last articles are\n" \
+	"-sufficiently done, thicken with flour, butter and milk, and serve it up.\n" \
+	"diff --git a/beef.txt b/beef.txt\n" \
+	"index 68f6182..f516580 100644\n" \
+	"--- a/beef.txt\n" \
+	"+++ b/beef.txt\n" \
+	"@@ -1,22 +1,10 @@\n" \
+	"-BEEF SOUP.\n" \
+	"+ASPARAGUS SOUP!\n" \
+	"\n" \
+	"-Take the hind shin of beef, cut off all the flesh off the leg-bone,\n" \
+	"-which must be taken away entirely, or the soup will be greasy. Wash the\n" \
+	"-meat clean and lay it in a pot, sprinkle over it one small\n" \
+	"-table-spoonful of pounded black pepper, and two of salt; three onions\n" \
+	"-the size of a hen's egg, cut small, six small carrots scraped and cut\n" \
+	"-up, two small turnips pared and cut into dice; pour on three quarts of\n" \
+	"-water, cover the pot close, and keep it gently and steadily boiling five\n" \
+	"-hours, which will leave about three pints of clear soup; do not let the\n" \
+	"-pot boil over, but take off the scum carefully, as it rises. When it has\n" \
+	"-boiled four hours, put in a small bundle of thyme and parsley, and a\n" \
+	"-pint of celery cut small, or a tea-spoonful of celery seed pounded.\n" \
+	"-These latter ingredients would lose their delicate flavour if boiled too\n" \
+	"-much. Just before you take it up, brown it in the following manner: put\n" \
+	"-a small table-spoonful of nice brown sugar into an iron skillet, set it\n" \
+	"-on the fire and stir it till it melts and looks very dark, pour into it\n" \
+	"-a ladle full of the soup, a little at a time; stirring it all the while.\n" \
+	"-Strain this browning and mix it well with the soup; take out the bundle\n" \
+	"-of thyme and parsley, put the nicest pieces of meat in your tureen, and\n" \
+	"-pour on the soup and vegetables; put in some toasted bread cut in dice,\n" \
+	"-and serve it up.\n" \
+	"+Take four large bunches of asparagus, scrape it nicely, cut off one inch\n" \
+	"+of the tops, and lay them in water, chop the stalks and put them on the\n" \
+	"+fire with a piece of bacon, a large onion cut up, and pepper and salt;\n" \
+	"+add two quarts of water, boil them till the stalks are quite soft, then\n" \
+	"+pulp them through a sieve, and strain the water to it, which must be put\n" \
+	"+back in the pot; put into it a chicken cut up, with the tops of\n" \
+	"+asparagus which had been laid by, boil it until these last articles are\n" \
+	"+sufficiently done, thicken with flour, butter and milk, and serve it up.\n" \
+	"diff --git a/notbeef.txt b/notbeef.txt\n" \
+	"new file mode 100644\n" \
+	"index 0000000..68f6182\n" \
+	"--- /dev/null\n" \
+	"+++ b/notbeef.txt\n" \
+	"@@ -0,0 +1,22 @@\n" \
+	"+BEEF SOUP.\n" \
+	"+\n" \
+	"+Take the hind shin of beef, cut off all the flesh off the leg-bone,\n" \
+	"+which must be taken away entirely, or the soup will be greasy. Wash the\n" \
+	"+meat clean and lay it in a pot, sprinkle over it one small\n" \
+	"+table-spoonful of pounded black pepper, and two of salt; three onions\n" \
+	"+the size of a hen's egg, cut small, six small carrots scraped and cut\n" \
+	"+up, two small turnips pared and cut into dice; pour on three quarts of\n" \
+	"+water, cover the pot close, and keep it gently and steadily boiling five\n" \
+	"+hours, which will leave about three pints of clear soup; do not let the\n" \
+	"+pot boil over, but take off the scum carefully, as it rises. When it has\n" \
+	"+boiled four hours, put in a small bundle of thyme and parsley, and a\n" \
+	"+pint of celery cut small, or a tea-spoonful of celery seed pounded.\n" \
+	"+These latter ingredients would lose their delicate flavour if boiled too\n" \
+	"+much. Just before you take it up, brown it in the following manner: put\n" \
+	"+a small table-spoonful of nice brown sugar into an iron skillet, set it\n" \
+	"+on the fire and stir it till it melts and looks very dark, pour into it\n" \
+	"+a ladle full of the soup, a little at a time; stirring it all the while.\n" \
+	"+Strain this browning and mix it well with the soup; take out the bundle\n" \
+	"+of thyme and parsley, put the nicest pieces of meat in your tureen, and\n" \
+	"+pour on the soup and vegetables; put in some toasted bread cut in dice,\n" \
+	"+and serve it up.\n"
+
+#define DIFF_RENAME_A_TO_B_TO_C_EXACT \
+	"diff --git a/asparagus.txt b/beef.txt\n" \
+	"similarity index 100%\n" \
+	"rename from asparagus.txt\n" \
+	"rename to beef.txt\n" \
+	"diff --git a/beef.txt b/notbeef.txt\n" \
+	"similarity index 100%\n" \
+	"rename from beef.txt\n" \
+	"rename to notbeef.txt\n"
+
+#define DIFF_RENAME_CIRCULAR \
+	"diff --git a/asparagus.txt b/beef.txt\n" \
+	"similarity index 100%\n" \
+	"rename from asparagus.txt\n" \
+	"rename to beef.txt\n" \
+	"diff --git a/beef.txt b/notbeef.txt\n" \
+	"similarity index 100%\n" \
+	"rename from beef.txt\n" \
+	"rename to asparagus.txt\n"
+
+#define DIFF_RENAME_2_TO_1 \
+	"diff --git a/asparagus.txt b/2.txt\n" \
+	"similarity index 100%\n" \
+	"rename from asparagus.txt\n" \
+	"rename to 2.txt\n" \
+	"diff --git a/beef.txt b/2.txt\n" \
+	"similarity index 100%\n" \
+	"rename from beef.txt\n" \
+	"rename to 2.txt\n"
+
+#define DIFF_RENAME_1_TO_2 \
+	"diff --git a/asparagus.txt b/2.txt\n" \
+	"similarity index 100%\n" \
+	"rename from asparagus.txt\n" \
+	"rename to 1.txt\n" \
+	"diff --git a/asparagus.txt b/2.txt\n" \
+	"similarity index 100%\n" \
+	"rename from asparagus.txt\n" \
+	"rename to 2.txt\n"
+
+#define DIFF_TWO_DELTAS_ONE_FILE \
+	"diff --git a/beef.txt b/beef.txt\n" \
+	"index 68f6182..235069d 100644\n" \
+	"--- a/beef.txt\n" \
+	"+++ b/beef.txt\n" \
+	"@@ -1,4 +1,4 @@\n" \
+	"-BEEF SOUP.\n" \
+	"+BEEF SOUP!\n" \
+	"\n" \
+	" Take the hind shin of beef, cut off all the flesh off the leg-bone,\n" \
+	" which must be taken away entirely, or the soup will be greasy. Wash the\n" \
+	"diff --git a/beef.txt b/beef.txt\n" \
+	"index 68f6182..e059eb5 100644\n" \
+	"--- a/beef.txt\n" \
+	"+++ b/beef.txt\n" \
+	"@@ -19,4 +19,4 @@ a ladle full of the soup, a little at a time; stirring it all the while.\n" \
+	" Strain this browning and mix it well with the soup; take out the bundle\n" \
+	" of thyme and parsley, put the nicest pieces of meat in your tureen, and\n" \
+	" pour on the soup and vegetables; put in some toasted bread cut in dice,\n" \
+	"-and serve it up.\n" \
+	"+and serve it up!\n"
+
+#define DIFF_TWO_DELTAS_ONE_NEW_FILE \
+	"diff --git a/newfile.txt b/newfile.txt\n" \
+	"new file mode 100644\n" \
+	"index 0000000..6434b13\n" \
+	"--- /dev/null\n" \
+	"+++ b/newfile.txt\n" \
+	"@@ -0,0 +1 @@\n" \
+	"+This is a new file.\n" \
+	"diff --git a/newfile.txt b/newfile.txt\n" \
+	"index 6434b13..08d4c44 100644\n" \
+	"--- a/newfile.txt\n" \
+	"+++ b/newfile.txt\n" \
+	"@@ -1 +1,3 @@\n" \
+	" This is a new file.\n" \
+	"+\n" \
+	"+This is another change to a new file.\n"
+
+#define DIFF_RENAME_AND_MODIFY_DELTAS \
+	"diff --git a/veal.txt b/asdf.txt\n" \
+	"similarity index 96%\n" \
+	"rename from veal.txt\n" \
+	"rename to asdf.txt\n" \
+	"index 94d2c01..292cb60 100644\n" \
+	"--- a/veal.txt\n" \
+	"+++ b/asdf.txt\n" \
+	"@@ -15,4 +15,4 @@ will curdle in the soup. For a change you may put a dozen ripe tomatos\n" \
+	" in, first taking off their skins, by letting them stand a few minutes in\n" \
+	" hot water, when they may be easily peeled. When made in this way you\n" \
+	" must thicken it with the flour only. Any part of the veal may be used,\n" \
+	"-but the shin or knuckle is the nicest.\n" \
+	"+but the shin or knuckle is the nicest!\n" \
+	"diff --git a/asdf.txt b/asdf.txt\n" \
+	"index 292cb60..61c686b 100644\n" \
+	"--- a/asdf.txt\n" \
+	"+++ b/asdf.txt\n" \
+	"@@ -1,4 +1,4 @@\n" \
+	"-VEAL SOUP!\n" \
+	"+VEAL SOUP\n" \
+	"\n" \
+	" Put into a pot three quarts of water, three onions cut small, one\n" \
+	" spoonful of black pepper pounded, and two of salt, with two or three\n"
+
+#define DIFF_RENAME_AFTER_MODIFY \
+	"diff --git a/veal.txt b/veal.txt\n" \
+	"index 292cb60..61c686b 100644\n" \
+	"--- a/veal.txt\n" \
+	"+++ b/veal.txt\n" \
+	"@@ -1,4 +1,4 @@\n" \
+	"-VEAL SOUP!\n" \
+	"+VEAL SOUP\n" \
+	"\n" \
+	" Put into a pot three quarts of water, three onions cut small, one\n" \
+	" spoonful of black pepper pounded, and two of salt, with two or three\n" \
+	"diff --git a/veal.txt b/other.txt\n" \
+	"similarity index 96%\n" \
+	"rename from veal.txt\n" \
+	"rename to other.txt\n" \
+	"index 94d2c01..292cb60 100644\n" \
+	"--- a/veal.txt\n" \
+	"+++ b/other.txt\n" \
+	"@@ -15,4 +15,4 @@ will curdle in the soup. For a change you may put a dozen ripe tomatos\n" \
+	" in, first taking off their skins, by letting them stand a few minutes in\n" \
+	" hot water, when they may be easily peeled. When made in this way you\n" \
+	" must thicken it with the flour only. Any part of the veal may be used,\n" \
+	"-but the shin or knuckle is the nicest.\n" \
+	"+but the shin or knuckle is the nicest!\n"
+
+#define DIFF_RENAME_AFTER_MODIFY_TARGET_PATH \
+	"diff --git a/beef.txt b/beef.txt\n" \
+	"index 292cb60..61c686b 100644\n" \
+	"--- a/beef.txt\n" \
+	"+++ b/beef.txt\n" \
+	"@@ -1,4 +1,4 @@\n" \
+	"-VEAL SOUP!\n" \
+	"+VEAL SOUP\n" \
+	"\n" \
+	" Put into a pot three quarts of water, three onions cut small, one\n" \
+	" spoonful of black pepper pounded, and two of salt, with two or three\n" \
+	"diff --git a/veal.txt b/beef.txt\n" \
+	"similarity index 96%\n" \
+	"rename from veal.txt\n" \
+	"rename to beef.txt\n" \
+	"index 94d2c01..292cb60 100644\n" \
+	"--- a/veal.txt\n" \
+	"+++ b/beef.txt\n" \
+	"@@ -15,4 +15,4 @@ will curdle in the soup. For a change you may put a dozen ripe tomatos\n" \
+	" in, first taking off their skins, by letting them stand a few minutes in\n" \
+	" hot water, when they may be easily peeled. When made in this way you\n" \
+	" must thicken it with the flour only. Any part of the veal may be used,\n" \
+	"-but the shin or knuckle is the nicest.\n" \
+	"+but the shin or knuckle is the nicest!\n"
+
+#define DIFF_RENAME_AND_MODIFY_SOURCE_PATH \
+	"diff --git a/veal.txt b/asdf.txt\n" \
+	"similarity index 96%\n" \
+	"rename from veal.txt\n" \
+	"rename to asdf.txt\n" \
+	"index 94d2c01..292cb60 100644\n" \
+	"--- a/veal.txt\n" \
+	"+++ b/asdf.txt\n" \
+	"@@ -15,4 +15,4 @@ will curdle in the soup. For a change you may put a dozen ripe tomatos\n" \
+	" in, first taking off their skins, by letting them stand a few minutes in\n" \
+	" hot water, when they may be easily peeled. When made in this way you\n" \
+	" must thicken it with the flour only. Any part of the veal may be used,\n" \
+	"-but the shin or knuckle is the nicest.\n" \
+	"+but the shin or knuckle is the nicest!\n" \
+	"diff --git a/veal.txt b/veal.txt\n" \
+	"index 292cb60..61c686b 100644\n" \
+	"--- a/veal.txt\n" \
+	"+++ b/veal.txt\n" \
+	"@@ -1,4 +1,4 @@\n" \
+	"-VEAL SOUP!\n" \
+	"+VEAL SOUP\n" \
+	"\n" \
+	" Put into a pot three quarts of water, three onions cut small, one\n" \
+	" spoonful of black pepper pounded, and two of salt, with two or three\n"
+
+#define DIFF_DELETE_AND_READD_FILE \
+	"diff --git a/asparagus.txt b/asparagus.txt\n" \
+	"deleted file mode 100644\n" \
+	"index f516580..0000000\n" \
+	"--- a/asparagus.txt\n" \
+	"+++ /dev/null\n" \
+	"@@ -1,10 +0,0 @@\n" \
+	"-ASPARAGUS SOUP!\n" \
+	"-\n" \
+	"-Take four large bunches of asparagus, scrape it nicely, cut off one inch\n" \
+	"-of the tops, and lay them in water, chop the stalks and put them on the\n" \
+	"-fire with a piece of bacon, a large onion cut up, and pepper and salt;\n" \
+	"-add two quarts of water, boil them till the stalks are quite soft, then\n" \
+	"-pulp them through a sieve, and strain the water to it, which must be put\n" \
+	"-back in the pot; put into it a chicken cut up, with the tops of\n" \
+	"-asparagus which had been laid by, boil it until these last articles are\n" \
+	"-sufficiently done, thicken with flour, butter and milk, and serve it up.\n" \
+	"diff --git a/asparagus.txt b/asparagus.txt\n" \
+	"new file mode 100644\n" \
+	"index 0000000..2dc7f8b\n" \
+	"--- /dev/null\n" \
+	"+++ b/asparagus.txt\n" \
+	"@@ -0,0 +1 @@\n" \
+	"+New file.\n" \
+
+#define DIFF_REMOVE_FILE_TWICE \
+	"diff --git a/asparagus.txt b/asparagus.txt\n" \
+	"deleted file mode 100644\n" \
+	"index f516580..0000000\n" \
+	"--- a/asparagus.txt\n" \
+	"+++ /dev/null\n" \
+	"@@ -1,10 +0,0 @@\n" \
+	"-ASPARAGUS SOUP!\n" \
+	"-\n" \
+	"-Take four large bunches of asparagus, scrape it nicely, cut off one inch\n" \
+	"-of the tops, and lay them in water, chop the stalks and put them on the\n" \
+	"-fire with a piece of bacon, a large onion cut up, and pepper and salt;\n" \
+	"-add two quarts of water, boil them till the stalks are quite soft, then\n" \
+	"-pulp them through a sieve, and strain the water to it, which must be put\n" \
+	"-back in the pot; put into it a chicken cut up, with the tops of\n" \
+	"-asparagus which had been laid by, boil it until these last articles are\n" \
+	"-sufficiently done, thicken with flour, butter and milk, and serve it up.\n" \
+	"diff --git a/asparagus.txt b/asparagus.txt\n" \
+	"deleted file mode 100644\n" \
+	"index f516580..0000000\n" \
+	"--- a/asparagus.txt\n" \
+	"+++ /dev/null\n" \
+	"@@ -1,10 +0,0 @@\n" \
+	"-ASPARAGUS SOUP!\n" \
+	"-\n" \
+	"-Take four large bunches of asparagus, scrape it nicely, cut off one inch\n" \
+	"-of the tops, and lay them in water, chop the stalks and put them on the\n" \
+	"-fire with a piece of bacon, a large onion cut up, and pepper and salt;\n" \
+	"-add two quarts of water, boil them till the stalks are quite soft, then\n" \
+	"-pulp them through a sieve, and strain the water to it, which must be put\n" \
+	"-back in the pot; put into it a chicken cut up, with the tops of\n" \
+	"-asparagus which had been laid by, boil it until these last articles are\n" \
+	"-sufficiently done, thicken with flour, butter and milk, and serve it up.\n"
+
+struct iterator_compare_data {
+	struct merge_index_entry *expected;
+	size_t cnt;
+	size_t idx;
+};
+
+static int iterator_compare(const git_index_entry *entry, void *_data)
+{
+	git_oid expected_id;
+
+	struct iterator_compare_data *data = (struct iterator_compare_data *)_data;
+
+	cl_assert_equal_i(GIT_IDXENTRY_STAGE(entry), data->expected[data->idx].stage);
+	cl_git_pass(git_oid_fromstr(&expected_id, data->expected[data->idx].oid_str));
+	cl_assert_equal_oid(&entry->id, &expected_id);
+	cl_assert_equal_i(entry->mode, data->expected[data->idx].mode);
+	cl_assert_equal_s(entry->path, data->expected[data->idx].path);
+
+	if (data->idx >= data->cnt)
+		return -1;
+
+	data->idx++;
+
+	return 0;
+}
+
+static void validate_apply_workdir(
+	git_repository *repo,
+	struct merge_index_entry *workdir_entries,
+	size_t workdir_cnt)
+{
+	git_index *index;
+	git_iterator *iterator;
+	git_iterator_options opts = GIT_ITERATOR_OPTIONS_INIT;
+	struct iterator_compare_data data = { workdir_entries, workdir_cnt };
+
+	opts.flags |= GIT_ITERATOR_INCLUDE_HASH;
+
+	cl_git_pass(git_repository_index(&index, repo));
+	cl_git_pass(git_iterator_for_workdir(&iterator, repo, index, NULL, &opts));
+
+	cl_git_pass(git_iterator_foreach(iterator, iterator_compare, &data));
+	cl_assert_equal_i(data.idx, data.cnt);
+
+	git_iterator_free(iterator);
+	git_index_free(index);
+}
+
+static void validate_apply_index(
+	git_repository *repo,
+	struct merge_index_entry *index_entries,
+	size_t index_cnt)
+{
+	git_index *index;
+	git_iterator *iterator;
+	struct iterator_compare_data data = { index_entries, index_cnt };
+
+	cl_git_pass(git_repository_index(&index, repo));
+	cl_git_pass(git_iterator_for_index(&iterator, repo, index, NULL));
+
+	cl_git_pass(git_iterator_foreach(iterator, iterator_compare, &data));
+	cl_assert_equal_i(data.idx, data.cnt);
+
+	git_iterator_free(iterator);
+	git_index_free(index);
+}
+
+static int iterator_eq(const git_index_entry **entry, void *_data)
+{
+	GIT_UNUSED(_data);
+
+	if (!entry[0] || !entry[1])
+		return -1;
+
+	cl_assert_equal_i(GIT_IDXENTRY_STAGE(entry[0]), GIT_IDXENTRY_STAGE(entry[1]));
+	cl_assert_equal_oid(&entry[0]->id, &entry[1]->id);
+	cl_assert_equal_i(entry[0]->mode, entry[1]->mode);
+	cl_assert_equal_s(entry[0]->path, entry[1]->path);
+
+	return 0;
+}
+
+static void validate_index_unchanged(git_repository *repo)
+{
+	git_tree *head;
+	git_index *index;
+	git_iterator *head_iterator, *index_iterator, *iterators[2];
+
+	cl_git_pass(git_repository_head_tree(&head, repo));
+	cl_git_pass(git_repository_index(&index, repo));
+
+	cl_git_pass(git_iterator_for_tree(&head_iterator, head, NULL));
+	cl_git_pass(git_iterator_for_index(&index_iterator, repo, index, NULL));
+
+	iterators[0] = head_iterator;
+	iterators[1] = index_iterator;
+
+	cl_git_pass(git_iterator_walk(iterators, 2, iterator_eq, NULL));
+
+	git_iterator_free(head_iterator);
+	git_iterator_free(index_iterator);
+
+	git_tree_free(head);
+	git_index_free(index);
+}
+
+static void validate_workdir_unchanged(git_repository *repo)
+{
+	git_tree *head;
+	git_index *index;
+	git_iterator *head_iterator, *workdir_iterator, *iterators[2];
+	git_iterator_options workdir_opts = GIT_ITERATOR_OPTIONS_INIT;
+
+	cl_git_pass(git_repository_head_tree(&head, repo));
+	cl_git_pass(git_repository_index(&index, repo));
+
+	workdir_opts.flags |= GIT_ITERATOR_INCLUDE_HASH;
+
+	cl_git_pass(git_iterator_for_tree(&head_iterator, head, NULL));
+	cl_git_pass(git_iterator_for_workdir(&workdir_iterator, repo, index, NULL, &workdir_opts));
+
+	iterators[0] = head_iterator;
+	iterators[1] = workdir_iterator;
+
+	cl_git_pass(git_iterator_walk(iterators, 2, iterator_eq, NULL));
+
+	git_iterator_free(head_iterator);
+	git_iterator_free(workdir_iterator);
+
+	git_tree_free(head);
+	git_index_free(index);
+}
diff --git a/tests/apply/both.c b/tests/apply/both.c
new file mode 100644
index 0000000..5091b8c
--- /dev/null
+++ b/tests/apply/both.c
@@ -0,0 +1,736 @@
+#include "clar_libgit2.h"
+#include "apply_helpers.h"
+
+static git_repository *repo;
+
+#define TEST_REPO_PATH "merge-recursive"
+
+void test_apply_both__initialize(void)
+{
+	git_oid oid;
+	git_commit *commit;
+
+	repo = cl_git_sandbox_init(TEST_REPO_PATH);
+
+	git_oid_fromstr(&oid, "539bd011c4822c560c1d17cab095006b7a10f707");
+	cl_git_pass(git_commit_lookup(&commit, repo, &oid));
+	cl_git_pass(git_reset(repo, (git_object *)commit, GIT_RESET_HARD, NULL));
+	git_commit_free(commit);
+}
+
+void test_apply_both__cleanup(void)
+{
+	cl_git_sandbox_cleanup();
+}
+
+void test_apply_both__generated_diff(void)
+{
+	git_oid a_oid, b_oid;
+	git_commit *a_commit, *b_commit;
+	git_tree *a_tree, *b_tree;
+	git_diff *diff;
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	git_oid_fromstr(&a_oid, "539bd011c4822c560c1d17cab095006b7a10f707");
+	git_oid_fromstr(&b_oid, "7c7bf85e978f1d18c0566f702d2cb7766b9c8d4f");
+	cl_git_pass(git_commit_lookup(&a_commit, repo, &a_oid));
+	cl_git_pass(git_commit_lookup(&b_commit, repo, &b_oid));
+
+	cl_git_pass(git_commit_tree(&a_tree, a_commit));
+	cl_git_pass(git_commit_tree(&b_tree, b_commit));
+
+	cl_git_pass(git_diff_tree_to_tree(&diff, repo, a_tree, b_tree, &diff_opts));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+	git_tree_free(a_tree);
+	git_tree_free(b_tree);
+	git_commit_free(a_commit);
+	git_commit_free(b_commit);
+}
+
+void test_apply_both__parsed_diff(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff,
+		DIFF_MODIFY_TWO_FILES, strlen(DIFF_MODIFY_TWO_FILES)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__removes_file(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" },
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+	    sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_DELETE_FILE,
+		strlen(DIFF_DELETE_FILE)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__adds_file(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "6370543fcfedb3e6516ec53b06158f3687dc1447", 0, "newfile.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" },
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+	    sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff,
+		DIFF_ADD_FILE, strlen(DIFF_ADD_FILE)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__application_failure_leaves_index_unmodified(void)
+{
+	git_diff *diff;
+	git_index *index;
+
+	const char *diff_file = DIFF_MODIFY_TWO_FILES;
+
+	struct merge_index_entry index_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+	};
+	size_t index_expected_cnt = sizeof(index_expected) /
+		sizeof(struct merge_index_entry);
+
+	/* mutate the index */
+	cl_git_pass(git_repository_index(&index, repo));
+	cl_git_pass(git_index_remove(index, "veal.txt", 0));
+	cl_git_pass(git_index_write(index));
+	git_index_free(index);
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_fail_with(GIT_EAPPLYFAIL, git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, index_expected, index_expected_cnt);
+	validate_workdir_unchanged(repo);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__index_must_match_workdir(void)
+{
+	git_diff *diff;
+	git_index *index;
+	git_index_entry idx_entry;
+
+	const char *diff_file = DIFF_MODIFY_TWO_FILES;
+
+	/*
+	 * Append a line to the end of the file in both the index and the
+	 * working directory.  Although the appended line would allow for
+	 * patch application in each, the line appended is different in
+	 * each, so the application should not be allowed.
+	 */
+	cl_git_append2file("merge-recursive/asparagus.txt",
+	    "This is a modification.\n");
+
+	cl_git_pass(git_repository_index(&index, repo));
+
+	memset(&idx_entry, 0, sizeof(git_index_entry));
+	idx_entry.mode = 0100644;
+	idx_entry.path = "asparagus.txt";
+	cl_git_pass(git_oid_fromstr(&idx_entry.id, "06d3fefb8726ab1099acc76e02dfb85e034b2538"));
+	cl_git_pass(git_index_add(index, &idx_entry));
+
+	cl_git_pass(git_index_write(index));
+	git_index_free(index);
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_fail_with(GIT_EAPPLYFAIL, git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__index_mode_must_match_workdir(void)
+{
+	git_diff *diff;
+
+	if (!cl_is_chmod_supported())
+		clar__skip();
+
+	/* Set a file in the working directory executable. */
+	cl_must_pass(p_chmod("merge-recursive/asparagus.txt", 0755));
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_MODIFY_TWO_FILES,
+	    strlen(DIFF_MODIFY_TWO_FILES)));
+	cl_git_fail_with(GIT_EAPPLYFAIL, git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__application_failure_leaves_workdir_unmodified(void)
+{
+	git_diff *diff;
+	git_index *index;
+
+	const char *diff_file = DIFF_MODIFY_TWO_FILES;
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "8684724651336001c5dbce74bed6736d2443958d", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+		sizeof(struct merge_index_entry);
+
+	/* mutate the workdir */
+	cl_git_rewritefile("merge-recursive/veal.txt",
+	    "This is a modification.\n");
+
+	cl_git_pass(git_repository_index(&index, repo));
+	git_index_add_bypath(index, "veal.txt");
+	cl_git_pass(git_index_write(index));
+	git_index_free(index);
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_fail_with(GIT_EAPPLYFAIL, git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__keeps_nonconflicting_changes(void)
+{
+	git_diff *diff;
+	git_index *index;
+	git_index_entry idx_entry;
+
+	const char *diff_file = DIFF_MODIFY_TWO_FILES;
+
+	struct merge_index_entry index_expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "898d12687fb35be271c27c795a6b32c8b51da79e", 0, "beef.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t index_expected_cnt = sizeof(index_expected) /
+		sizeof(struct merge_index_entry);
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "f75ba05f340c51065cbea2e1fdbfe5fe13144c97", 0, "gravy.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+		sizeof(struct merge_index_entry);
+
+	/* mutate the index */
+	cl_git_pass(git_repository_index(&index, repo));
+
+	memset(&idx_entry, 0, sizeof(git_index_entry));
+	idx_entry.mode = 0100644;
+	idx_entry.path = "beef.txt";
+	cl_git_pass(git_oid_fromstr(&idx_entry.id, "898d12687fb35be271c27c795a6b32c8b51da79e"));
+	git_index_add(index, &idx_entry);
+
+	cl_git_pass(git_index_remove(index, "bouilli.txt", 0));
+	cl_git_pass(git_index_write(index));
+	git_index_free(index);
+
+	/* and mutate the working directory */
+	cl_git_rmfile("merge-recursive/oyster.txt");
+	cl_git_rewritefile("merge-recursive/gravy.txt", "Hello, world.\n");
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, index_expected, index_expected_cnt);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__can_apply_nonconflicting_file_changes(void)
+{
+	git_diff *diff;
+	git_index *index;
+
+	const char *diff_file = DIFF_MODIFY_TWO_FILES;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "f8a701c8a1a22c1729ee50faff1111f2d64f96fc", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	/*
+	 * Replace the workdir file with a version that is different than
+	 * HEAD but such that the patch still applies cleanly.  This item
+	 * has a new line appended.
+	 */
+	cl_git_append2file("merge-recursive/asparagus.txt",
+	    "This line is added in the index and the workdir.\n");
+
+	cl_git_pass(git_repository_index(&index, repo));
+	git_index_add_bypath(index, "asparagus.txt");
+	cl_git_pass(git_index_write(index));
+	git_index_free(index);
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__honors_crlf_attributes(void)
+{
+	git_diff *diff;
+	git_oid oid;
+	git_commit *commit;
+
+	const char *diff_file = DIFF_MODIFY_TWO_FILES;
+
+	struct merge_index_entry index_expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t index_expected_cnt = sizeof(index_expected) /
+		sizeof(struct merge_index_entry);
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "176a458f94e0ea5272ce67c36bf30b6be9caf623", 0, ".gitattributes" },
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_mkfile("merge-recursive/.gitattributes", "* text=auto\n");
+
+	cl_git_rmfile("merge-recursive/asparagus.txt");
+	cl_git_rmfile("merge-recursive/veal.txt");
+
+	git_oid_fromstr(&oid, "539bd011c4822c560c1d17cab095006b7a10f707");
+	cl_git_pass(git_commit_lookup(&commit, repo, &oid));
+	cl_git_pass(git_reset(repo, (git_object *)commit, GIT_RESET_HARD, NULL));
+	git_commit_free(commit);
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, index_expected, index_expected_cnt);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__rename(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "notbeef.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" },
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_RENAME_FILE,
+		strlen(DIFF_RENAME_FILE)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__rename_and_modify(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "6fa10147f00fe1fab1d5e835529a9dad53db8552", 0, "notbeef.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" },
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_RENAME_AND_MODIFY_FILE,
+		strlen(DIFF_RENAME_AND_MODIFY_FILE)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+    validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__rename_a_to_b_to_c(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "notbeef.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" },
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_RENAME_A_TO_B_TO_C,
+		strlen(DIFF_RENAME_A_TO_B_TO_C)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__rename_a_to_b_to_c_exact(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "notbeef.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" },
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_RENAME_A_TO_B_TO_C_EXACT,
+		strlen(DIFF_RENAME_A_TO_B_TO_C_EXACT)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__rename_circular(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "asparagus.txt" },
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" }
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_RENAME_CIRCULAR,
+		strlen(DIFF_RENAME_CIRCULAR)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__rename_2_to_1(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "2.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" }
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_RENAME_2_TO_1,
+		strlen(DIFF_RENAME_2_TO_1)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__rename_1_to_2(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "1.txt" },
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "2.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" }
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_RENAME_1_TO_2,
+		strlen(DIFF_RENAME_1_TO_2)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__two_deltas_one_file(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "0a9fd4415635e72573f0f6b5e68084cfe18f5075", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" }
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_TWO_DELTAS_ONE_FILE,
+		strlen(DIFF_TWO_DELTAS_ONE_FILE)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__two_deltas_one_new_file(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "08d4c445cf0078f3d9b604b82f32f4d87e083325", 0, "newfile.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" }
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_TWO_DELTAS_ONE_NEW_FILE,
+		strlen(DIFF_TWO_DELTAS_ONE_NEW_FILE)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__rename_and_modify_deltas(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "61c686bed39684eee8a2757ceb1291004a21333f", 0, "asdf.txt" },
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_RENAME_AND_MODIFY_DELTAS,
+		strlen(DIFF_RENAME_AND_MODIFY_DELTAS)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__rename_delta_after_modify_delta(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "292cb60ce5e25c337c5b6e12957bbbfe1be4bf49", 0, "other.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "c8c120f466591bbe3b8867361d5ec3cdd9fda756", 0, "veal.txt" }
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_RENAME_AFTER_MODIFY,
+		strlen(DIFF_RENAME_AFTER_MODIFY)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__cant_rename_after_modify_nonexistent_target_path(void)
+{
+	git_diff *diff;
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_RENAME_AFTER_MODIFY_TARGET_PATH,
+		strlen(DIFF_RENAME_AFTER_MODIFY_TARGET_PATH)));
+	cl_git_fail(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__cant_modify_source_path_after_rename(void)
+{
+	git_diff *diff;
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_RENAME_AND_MODIFY_SOURCE_PATH,
+		strlen(DIFF_RENAME_AND_MODIFY_SOURCE_PATH)));
+	cl_git_fail(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__readd_deleted_file(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "2dc7f8b24ba27f3888368bd180df03ff4c6c6fab", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" }
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_DELETE_AND_READD_FILE,
+		strlen(DIFF_DELETE_AND_READD_FILE)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_both__cant_remove_file_twice(void)
+{
+	git_diff *diff;
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_REMOVE_FILE_TWICE,
+		strlen(DIFF_REMOVE_FILE_TWICE)));
+	cl_git_fail(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	git_diff_free(diff);
+}
diff --git a/tests/apply/callbacks.c b/tests/apply/callbacks.c
new file mode 100644
index 0000000..1b759dc
--- /dev/null
+++ b/tests/apply/callbacks.c
@@ -0,0 +1,128 @@
+#include "clar_libgit2.h"
+#include "apply_helpers.h"
+
+static git_repository *repo;
+
+#define TEST_REPO_PATH "merge-recursive"
+
+void test_apply_callbacks__initialize(void)
+{
+	git_oid oid;
+	git_commit *commit;
+
+	repo = cl_git_sandbox_init(TEST_REPO_PATH);
+
+	git_oid_fromstr(&oid, "539bd011c4822c560c1d17cab095006b7a10f707");
+	cl_git_pass(git_commit_lookup(&commit, repo, &oid));
+	cl_git_pass(git_reset(repo, (git_object *)commit, GIT_RESET_HARD, NULL));
+	git_commit_free(commit);
+}
+
+void test_apply_callbacks__cleanup(void)
+{
+	cl_git_sandbox_cleanup();
+}
+
+static int delta_abort_cb(const git_diff_delta *delta, void *payload)
+{
+	GIT_UNUSED(payload);
+
+	if (!strcmp(delta->old_file.path, "veal.txt"))
+		return -99;
+
+	return 0;
+}
+
+void test_apply_callbacks__delta_aborts(void)
+{
+	git_diff *diff;
+	git_apply_options opts = GIT_APPLY_OPTIONS_INIT;
+
+	opts.delta_cb = delta_abort_cb;
+
+	cl_git_pass(git_diff_from_buffer(&diff,
+		DIFF_MODIFY_TWO_FILES, strlen(DIFF_MODIFY_TWO_FILES)));
+	cl_git_fail_with(-99,
+		git_apply(repo, diff, GIT_APPLY_LOCATION_INDEX, &opts));
+
+	validate_index_unchanged(repo);
+	validate_workdir_unchanged(repo);
+
+	git_diff_free(diff);
+}
+
+static int delta_skip_cb(const git_diff_delta *delta, void *payload)
+{
+	GIT_UNUSED(payload);
+
+	if (!strcmp(delta->old_file.path, "asparagus.txt"))
+		return 1;
+
+	return 0;
+}
+
+void test_apply_callbacks__delta_can_skip(void)
+{
+	git_diff *diff;
+	git_apply_options opts = GIT_APPLY_OPTIONS_INIT;
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+	    sizeof(struct merge_index_entry);
+
+	opts.delta_cb = delta_skip_cb;
+
+	cl_git_pass(git_diff_from_buffer(&diff,
+		DIFF_MODIFY_TWO_FILES, strlen(DIFF_MODIFY_TWO_FILES)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_WORKDIR, &opts));
+
+	validate_index_unchanged(repo);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+static int hunk_skip_odds_cb(const git_diff_hunk *hunk, void *payload)
+{
+	int *count = (int *)payload;
+	GIT_UNUSED(hunk);
+
+	return ((*count)++ % 2 == 1);
+}
+
+void test_apply_callbacks__hunk_can_skip(void)
+{
+	git_diff *diff;
+	git_apply_options opts = GIT_APPLY_OPTIONS_INIT;
+	int count = 0;
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "06f751b6ba4f017ddbf4248015768300268e092a", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+	    sizeof(struct merge_index_entry);
+
+	opts.hunk_cb = hunk_skip_odds_cb;
+	opts.payload = &count;
+
+	cl_git_pass(git_diff_from_buffer(&diff,
+		DIFF_MANY_CHANGES_ONE, strlen(DIFF_MANY_CHANGES_ONE)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_WORKDIR, &opts));
+
+	validate_index_unchanged(repo);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+}
diff --git a/tests/apply/fromdiff.c b/tests/apply/fromdiff.c
index 6110609..8a6d8fa 100644
--- a/tests/apply/fromdiff.c
+++ b/tests/apply/fromdiff.c
@@ -49,7 +49,7 @@ static int apply_gitbuf(
 		cl_assert_equal_s(patch_expected, patchbuf.ptr);
 	}
 
-	error = git_apply__patch(&result, &filename, &mode, old ? old->ptr : NULL, old ? old->size : 0, patch);
+	error = git_apply__patch(&result, &filename, &mode, old ? old->ptr : NULL, old ? old->size : 0, patch, NULL);
 
 	if (error == 0 && new == NULL) {
 		cl_assert_equal_i(0, result.size);
@@ -150,6 +150,52 @@ void test_apply_fromdiff__prepend_nocontext(void)
 		PATCH_ORIGINAL_TO_PREPEND_NOCONTEXT, &diff_opts));
 }
 
+void test_apply_fromdiff__prepend_and_change(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_PREPEND_AND_CHANGE, "file.txt",
+		PATCH_ORIGINAL_TO_PREPEND_AND_CHANGE, NULL));
+}
+
+void test_apply_fromdiff__prepend_and_change_nocontext(void)
+{
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+	diff_opts.context_lines = 0;
+
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_PREPEND_AND_CHANGE, "file.txt",
+		PATCH_ORIGINAL_TO_PREPEND_AND_CHANGE_NOCONTEXT, &diff_opts));
+}
+
+void test_apply_fromdiff__delete_and_change(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_DELETE_AND_CHANGE, "file.txt",
+		PATCH_ORIGINAL_TO_DELETE_AND_CHANGE, NULL));
+}
+
+void test_apply_fromdiff__delete_and_change_nocontext(void)
+{
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+	diff_opts.context_lines = 0;
+
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_DELETE_AND_CHANGE, "file.txt",
+		PATCH_ORIGINAL_TO_DELETE_AND_CHANGE_NOCONTEXT, &diff_opts));
+}
+
+void test_apply_fromdiff__delete_firstline(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_DELETE_FIRSTLINE, "file.txt",
+		PATCH_ORIGINAL_TO_DELETE_FIRSTLINE, NULL));
+}
+
 void test_apply_fromdiff__append(void)
 {
 	cl_git_pass(apply_buf(
diff --git a/tests/apply/fromfile.c b/tests/apply/fromfile.c
index 0ace639..6d4379b 100644
--- a/tests/apply/fromfile.c
+++ b/tests/apply/fromfile.c
@@ -39,7 +39,7 @@ static int apply_patchfile(
 
 	cl_git_pass(git_patch_from_buffer(&patch, patchfile, strlen(patchfile), NULL));
 
-	error = git_apply__patch(&result, &filename, &mode, old, old_len, patch);
+	error = git_apply__patch(&result, &filename, &mode, old, old_len, patch, NULL);
 
 	if (error == 0) {
 		cl_assert_equal_i(new_len, result.size);
diff --git a/tests/apply/index.c b/tests/apply/index.c
new file mode 100644
index 0000000..9c9094c
--- /dev/null
+++ b/tests/apply/index.c
@@ -0,0 +1,321 @@
+#include "clar_libgit2.h"
+#include "apply_helpers.h"
+
+static git_repository *repo;
+
+#define TEST_REPO_PATH "merge-recursive"
+
+void test_apply_index__initialize(void)
+{
+	git_oid oid;
+	git_commit *commit;
+
+	repo = cl_git_sandbox_init(TEST_REPO_PATH);
+
+	git_oid_fromstr(&oid, "539bd011c4822c560c1d17cab095006b7a10f707");
+	cl_git_pass(git_commit_lookup(&commit, repo, &oid));
+	cl_git_pass(git_reset(repo, (git_object *)commit, GIT_RESET_HARD, NULL));
+	git_commit_free(commit);
+}
+
+void test_apply_index__cleanup(void)
+{
+	cl_git_sandbox_cleanup();
+}
+
+void test_apply_index__generate_diff(void)
+{
+	git_oid a_oid, b_oid;
+	git_commit *a_commit, *b_commit;
+	git_tree *a_tree, *b_tree;
+	git_diff *diff;
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+
+	struct merge_index_entry index_expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t index_expected_cnt = sizeof(index_expected) /
+		sizeof(struct merge_index_entry);
+
+	git_oid_fromstr(&a_oid, "539bd011c4822c560c1d17cab095006b7a10f707");
+	git_oid_fromstr(&b_oid, "7c7bf85e978f1d18c0566f702d2cb7766b9c8d4f");
+	cl_git_pass(git_commit_lookup(&a_commit, repo, &a_oid));
+	cl_git_pass(git_commit_lookup(&b_commit, repo, &b_oid));
+
+	cl_git_pass(git_commit_tree(&a_tree, a_commit));
+	cl_git_pass(git_commit_tree(&b_tree, b_commit));
+
+	cl_git_pass(git_diff_tree_to_tree(&diff, repo, a_tree, b_tree, &diff_opts));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_INDEX, NULL));
+
+	validate_apply_index(repo, index_expected, index_expected_cnt);
+	validate_workdir_unchanged(repo);
+
+	git_diff_free(diff);
+	git_tree_free(a_tree);
+	git_tree_free(b_tree);
+	git_commit_free(a_commit);
+	git_commit_free(b_commit);
+}
+
+void test_apply_index__parsed_diff(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry index_expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t index_expected_cnt = sizeof(index_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff,
+		DIFF_MODIFY_TWO_FILES, strlen(DIFF_MODIFY_TWO_FILES)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_INDEX, NULL));
+
+	validate_apply_index(repo, index_expected, index_expected_cnt);
+	validate_workdir_unchanged(repo);
+
+	git_diff_free(diff);
+}
+
+void test_apply_index__removes_file(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry index_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" },
+	};
+	size_t index_expected_cnt = sizeof(index_expected) /
+	    sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_DELETE_FILE,
+		strlen(DIFF_DELETE_FILE)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_INDEX, NULL));
+
+	validate_apply_index(repo, index_expected, index_expected_cnt);
+	validate_workdir_unchanged(repo);
+
+	git_diff_free(diff);
+}
+
+void test_apply_index__adds_file(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry index_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "6370543fcfedb3e6516ec53b06158f3687dc1447", 0, "newfile.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" },
+	};
+	size_t index_expected_cnt = sizeof(index_expected) /
+	    sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff,
+		DIFF_ADD_FILE, strlen(DIFF_ADD_FILE)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_INDEX, NULL));
+
+	validate_apply_index(repo, index_expected, index_expected_cnt);
+	validate_workdir_unchanged(repo);
+
+	git_diff_free(diff);
+}
+
+void test_apply_index__modified_workdir_with_unmodified_index_is_ok(void)
+{
+	git_diff *diff;
+
+	const char *diff_file = DIFF_MODIFY_TWO_FILES;
+
+	struct merge_index_entry index_expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t index_expected_cnt = sizeof(index_expected) /
+		sizeof(struct merge_index_entry);
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "f75ba05f340c51065cbea2e1fdbfe5fe13144c97", 0, "veal.txt" }
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+		sizeof(struct merge_index_entry);
+
+	/* mutate the workdir and leave the index matching HEAD */
+	cl_git_rmfile("merge-recursive/asparagus.txt");
+	cl_git_rewritefile("merge-recursive/veal.txt", "Hello, world.\n");
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_INDEX, NULL));
+
+	validate_apply_index(repo, index_expected, index_expected_cnt);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_index__application_failure_leaves_index_unmodified(void)
+{
+	git_diff *diff;
+	git_index *index;
+
+	const char *diff_file = DIFF_MODIFY_TWO_FILES;
+
+	struct merge_index_entry index_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+	};
+	size_t index_expected_cnt = sizeof(index_expected) /
+		sizeof(struct merge_index_entry);
+
+	/* mutate the index */
+	cl_git_pass(git_repository_index(&index, repo));
+	cl_git_pass(git_index_remove(index, "veal.txt", 0));
+	cl_git_pass(git_index_write(index));
+	git_index_free(index);
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_fail_with(GIT_EAPPLYFAIL, git_apply(repo, diff, GIT_APPLY_LOCATION_INDEX, NULL));
+
+	validate_apply_index(repo, index_expected, index_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_index__keeps_nonconflicting_changes(void)
+{
+	git_diff *diff;
+	git_index *index;
+	git_index_entry idx_entry;
+
+	const char *diff_file = DIFF_MODIFY_TWO_FILES;
+
+	struct merge_index_entry index_expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "898d12687fb35be271c27c795a6b32c8b51da79e", 0, "beef.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t index_expected_cnt = sizeof(index_expected) /
+		sizeof(struct merge_index_entry);
+
+	/* mutate the index */
+	cl_git_pass(git_repository_index(&index, repo));
+
+	memset(&idx_entry, 0, sizeof(git_index_entry));
+	idx_entry.mode = 0100644;
+	idx_entry.path = "beef.txt";
+	cl_git_pass(git_oid_fromstr(&idx_entry.id, "898d12687fb35be271c27c795a6b32c8b51da79e"));
+	cl_git_pass(git_index_add(index, &idx_entry));
+
+	cl_git_pass(git_index_remove(index, "bouilli.txt", 0));
+	cl_git_pass(git_index_write(index));
+	git_index_free(index);
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_INDEX, NULL));
+
+	validate_apply_index(repo, index_expected, index_expected_cnt);
+	validate_workdir_unchanged(repo);
+
+	git_diff_free(diff);
+}
+
+void test_apply_index__can_apply_nonconflicting_file_changes(void)
+{
+	git_diff *diff;
+	git_index *index;
+	git_index_entry idx_entry;
+
+	const char *diff_file = DIFF_MODIFY_TWO_FILES;
+
+	struct merge_index_entry index_expected[] = {
+		{ 0100644, "4f2d1645dee99ced096877911de540c65ade2ef8", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t index_expected_cnt = sizeof(index_expected) /
+		sizeof(struct merge_index_entry);
+
+	/*
+	 * Replace the index entry with a version that is different than
+	 * HEAD but such that the patch still applies cleanly.  This item
+	 * has a new line appended.
+	 */
+
+	cl_git_pass(git_repository_index(&index, repo));
+
+	memset(&idx_entry, 0, sizeof(git_index_entry));
+	idx_entry.mode = 0100644;
+	idx_entry.path = "asparagus.txt";
+	cl_git_pass(git_oid_fromstr(&idx_entry.id, "06d3fefb8726ab1099acc76e02dfb85e034b2538"));
+	cl_git_pass(git_index_add(index, &idx_entry));
+
+	cl_git_pass(git_index_write(index));
+	git_index_free(index);
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_INDEX, NULL));
+
+	validate_apply_index(repo, index_expected, index_expected_cnt);
+	validate_workdir_unchanged(repo);
+
+	git_diff_free(diff);
+}
+
+void test_apply_index__change_mode(void)
+{
+	git_diff *diff;
+
+	const char *diff_file = DIFF_EXECUTABLE_FILE;
+
+	struct merge_index_entry index_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100755, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" },
+	};
+	size_t index_expected_cnt = sizeof(index_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_INDEX, NULL));
+
+	validate_apply_index(repo, index_expected, index_expected_cnt);
+	validate_workdir_unchanged(repo);
+
+	git_diff_free(diff);
+}
diff --git a/tests/apply/partial.c b/tests/apply/partial.c
new file mode 100644
index 0000000..243dccf
--- /dev/null
+++ b/tests/apply/partial.c
@@ -0,0 +1,232 @@
+#include "clar_libgit2.h"
+#include "git2/sys/repository.h"
+
+#include "apply.h"
+#include "repository.h"
+#include "buf_text.h"
+
+#include "../patch/patch_common.h"
+
+static git_repository *repo = NULL;
+
+void test_apply_partial__initialize(void)
+{
+	repo = cl_git_sandbox_init("renames");
+}
+
+void test_apply_partial__cleanup(void)
+{
+	cl_git_sandbox_cleanup();
+}
+
+static int skip_addition(
+	const git_diff_hunk *hunk,
+	void *payload)
+{
+	GIT_UNUSED(payload);
+
+	return (hunk->new_lines > hunk->old_lines) ? 1 : 0;
+}
+
+static int skip_deletion(
+	const git_diff_hunk *hunk,
+	void *payload)
+{
+	GIT_UNUSED(payload);
+
+	return (hunk->new_lines < hunk->old_lines) ? 1 : 0;
+}
+
+static int skip_change(
+	const git_diff_hunk *hunk,
+	void *payload)
+{
+	GIT_UNUSED(payload);
+
+	return (hunk->new_lines == hunk->old_lines) ? 1 : 0;
+}
+
+static int abort_addition(
+	const git_diff_hunk *hunk,
+	void *payload)
+{
+	GIT_UNUSED(payload);
+
+	return (hunk->new_lines > hunk->old_lines) ? GIT_EUSER : 0;
+}
+
+static int abort_deletion(
+	const git_diff_hunk *hunk,
+	void *payload)
+{
+	GIT_UNUSED(payload);
+
+	return (hunk->new_lines < hunk->old_lines) ? GIT_EUSER : 0;
+}
+
+static int abort_change(
+	const git_diff_hunk *hunk,
+	void *payload)
+{
+	GIT_UNUSED(payload);
+
+	return (hunk->new_lines == hunk->old_lines) ? GIT_EUSER : 0;
+}
+
+static int apply_buf(
+	const char *old,
+	const char *oldname,
+	const char *new,
+	const char *newname,
+	const char *expected,
+	const git_diff_options *diff_opts,
+	git_apply_hunk_cb hunk_cb,
+	void *payload)
+{
+	git_patch *patch;
+	git_buf result = GIT_BUF_INIT;
+	git_buf patchbuf = GIT_BUF_INIT;
+	git_apply_options opts = GIT_APPLY_OPTIONS_INIT;
+	char *filename;
+	unsigned int mode;
+	int error;
+	size_t oldsize = strlen(old);
+	size_t newsize = strlen(new);
+
+	opts.hunk_cb = hunk_cb;
+	opts.payload = payload;
+
+	cl_git_pass(git_patch_from_buffers(&patch, old, oldsize, oldname, new, newsize, newname, diff_opts));
+	if ((error = git_apply__patch(&result, &filename, &mode, old, oldsize, patch, &opts)) == 0) {
+		cl_assert_equal_s(expected, result.ptr);
+		cl_assert_equal_s(newname, filename);
+		cl_assert_equal_i(0100644, mode);
+	}
+
+	git__free(filename);
+	git_buf_free(&result);
+	git_buf_free(&patchbuf);
+	git_patch_free(patch);
+
+	return error;
+}
+
+void test_apply_partial__prepend_and_change_skip_addition(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_PREPEND_AND_CHANGE, "file.txt",
+		FILE_ORIGINAL, NULL, skip_addition, NULL));
+}
+
+void test_apply_partial__prepend_and_change_nocontext_skip_addition(void)
+{
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+	diff_opts.context_lines = 0;
+
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_PREPEND_AND_CHANGE, "file.txt",
+		FILE_CHANGE_MIDDLE, &diff_opts, skip_addition, NULL));
+}
+
+void test_apply_partial__prepend_and_change_nocontext_abort_addition(void)
+{
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+	diff_opts.context_lines = 0;
+
+	cl_git_fail(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_PREPEND_AND_CHANGE, "file.txt",
+		FILE_ORIGINAL, &diff_opts, abort_addition, NULL));
+}
+
+void test_apply_partial__prepend_and_change_skip_change(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_PREPEND_AND_CHANGE, "file.txt",
+		FILE_PREPEND_AND_CHANGE, NULL, skip_change, NULL));
+}
+
+void test_apply_partial__prepend_and_change_nocontext_skip_change(void)
+{
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+	diff_opts.context_lines = 0;
+
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_PREPEND_AND_CHANGE, "file.txt",
+		FILE_PREPEND, &diff_opts, skip_change, NULL));
+}
+
+void test_apply_partial__prepend_and_change_nocontext_abort_change(void)
+{
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+	diff_opts.context_lines = 0;
+
+	cl_git_fail(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_PREPEND_AND_CHANGE, "file.txt",
+		FILE_PREPEND, &diff_opts, abort_change, NULL));
+}
+
+void test_apply_partial__delete_and_change_skip_deletion(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_DELETE_AND_CHANGE, "file.txt",
+		FILE_ORIGINAL, NULL, skip_deletion, NULL));
+}
+
+void test_apply_partial__delete_and_change_nocontext_skip_deletion(void)
+{
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+	diff_opts.context_lines = 0;
+
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_DELETE_AND_CHANGE, "file.txt",
+		FILE_CHANGE_MIDDLE, &diff_opts, skip_deletion, NULL));
+}
+
+void test_apply_partial__delete_and_change_nocontext_abort_deletion(void)
+{
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+	diff_opts.context_lines = 0;
+
+	cl_git_fail(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_DELETE_AND_CHANGE, "file.txt",
+		FILE_ORIGINAL, &diff_opts, abort_deletion, NULL));
+}
+
+void test_apply_partial__delete_and_change_skip_change(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_DELETE_AND_CHANGE, "file.txt",
+		FILE_DELETE_AND_CHANGE, NULL, skip_change, NULL));
+}
+
+void test_apply_partial__delete_and_change_nocontext_skip_change(void)
+{
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+	diff_opts.context_lines = 0;
+
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_DELETE_AND_CHANGE, "file.txt",
+		FILE_DELETE_FIRSTLINE, &diff_opts, skip_change, NULL));
+}
+
+void test_apply_partial__delete_and_change_nocontext_abort_change(void)
+{
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+	diff_opts.context_lines = 0;
+
+	cl_git_fail(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_DELETE_AND_CHANGE, "file.txt",
+		FILE_DELETE_FIRSTLINE, &diff_opts, abort_change, NULL));
+}
diff --git a/tests/apply/tree.c b/tests/apply/tree.c
new file mode 100644
index 0000000..f35b13c
--- /dev/null
+++ b/tests/apply/tree.c
@@ -0,0 +1,58 @@
+#include "clar_libgit2.h"
+#include "../merge/merge_helpers.h"
+
+static git_repository *repo;
+
+#define TEST_REPO_PATH "merge-recursive"
+
+
+void test_apply_tree__initialize(void)
+{
+	repo = cl_git_sandbox_init(TEST_REPO_PATH);
+}
+
+void test_apply_tree__cleanup(void)
+{
+	cl_git_sandbox_cleanup();
+}
+
+void test_apply_tree__one(void)
+{
+	git_oid a_oid, b_oid;
+	git_commit *a_commit, *b_commit;
+	git_tree *a_tree, *b_tree;
+	git_diff *diff;
+	git_index *index = NULL;
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
+
+	struct merge_index_entry expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+
+	git_oid_fromstr(&a_oid, "539bd011c4822c560c1d17cab095006b7a10f707");
+	git_oid_fromstr(&b_oid, "7c7bf85e978f1d18c0566f702d2cb7766b9c8d4f");
+
+	cl_git_pass(git_commit_lookup(&a_commit, repo, &a_oid));
+	cl_git_pass(git_commit_lookup(&b_commit, repo, &b_oid));
+
+	cl_git_pass(git_commit_tree(&a_tree, a_commit));
+	cl_git_pass(git_commit_tree(&b_tree, b_commit));
+
+	cl_git_pass(git_diff_tree_to_tree(&diff, repo, a_tree, b_tree, &opts));
+
+	cl_git_pass(git_apply_to_tree(&index, repo, a_tree, diff, NULL));
+	merge_test_index(index, expected, 6);
+
+	git_index_free(index);
+	git_diff_free(diff);
+	git_tree_free(a_tree);
+	git_tree_free(b_tree);
+	git_commit_free(a_commit);
+	git_commit_free(b_commit);
+}
+
diff --git a/tests/apply/workdir.c b/tests/apply/workdir.c
new file mode 100644
index 0000000..1a82925
--- /dev/null
+++ b/tests/apply/workdir.c
@@ -0,0 +1,358 @@
+#include "clar_libgit2.h"
+#include "apply_helpers.h"
+
+static git_repository *repo;
+
+#define TEST_REPO_PATH "merge-recursive"
+
+void test_apply_workdir__initialize(void)
+{
+	git_oid oid;
+	git_commit *commit;
+
+	repo = cl_git_sandbox_init(TEST_REPO_PATH);
+
+	git_oid_fromstr(&oid, "539bd011c4822c560c1d17cab095006b7a10f707");
+	cl_git_pass(git_commit_lookup(&commit, repo, &oid));
+	cl_git_pass(git_reset(repo, (git_object *)commit, GIT_RESET_HARD, NULL));
+	git_commit_free(commit);
+}
+
+void test_apply_workdir__cleanup(void)
+{
+	cl_git_sandbox_cleanup();
+}
+
+void test_apply_workdir__generated_diff(void)
+{
+	git_oid a_oid, b_oid;
+	git_commit *a_commit, *b_commit;
+	git_tree *a_tree, *b_tree;
+	git_diff *diff;
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+		sizeof(struct merge_index_entry);
+
+	git_oid_fromstr(&a_oid, "539bd011c4822c560c1d17cab095006b7a10f707");
+	git_oid_fromstr(&b_oid, "7c7bf85e978f1d18c0566f702d2cb7766b9c8d4f"); cl_git_pass(git_commit_lookup(&a_commit, repo, &a_oid));
+	cl_git_pass(git_commit_lookup(&b_commit, repo, &b_oid));
+
+	cl_git_pass(git_commit_tree(&a_tree, a_commit));
+	cl_git_pass(git_commit_tree(&b_tree, b_commit));
+
+	cl_git_pass(git_diff_tree_to_tree(&diff, repo, a_tree, b_tree, &opts));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_WORKDIR, NULL));
+
+	validate_index_unchanged(repo);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+	git_tree_free(a_tree);
+	git_tree_free(b_tree);
+	git_commit_free(a_commit);
+	git_commit_free(b_commit);
+}
+
+void test_apply_workdir__parsed_diff(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+	    sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff,
+		DIFF_MODIFY_TWO_FILES, strlen(DIFF_MODIFY_TWO_FILES)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_WORKDIR, NULL));
+
+	validate_index_unchanged(repo);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_workdir__removes_file(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+	    sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_DELETE_FILE,
+		strlen(DIFF_DELETE_FILE)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_WORKDIR, NULL));
+
+	validate_index_unchanged(repo);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_workdir__adds_file(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "6370543fcfedb3e6516ec53b06158f3687dc1447", 0, "newfile.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+	    sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff,
+		DIFF_ADD_FILE, strlen(DIFF_ADD_FILE)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_WORKDIR, NULL));
+
+	validate_index_unchanged(repo);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_workdir__modified_index_with_unmodified_workdir_is_ok(void)
+{
+	git_index *index;
+	git_index_entry idx_entry = {{0}};
+	git_diff *diff;
+
+	const char *diff_file = DIFF_MODIFY_TWO_FILES;
+
+	struct merge_index_entry index_expected[] = {
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "veal.txt" }
+	};
+	size_t index_expected_cnt = sizeof(index_expected) /
+		sizeof(struct merge_index_entry);
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+		sizeof(struct merge_index_entry);
+
+	/* mutate the index and leave the workdir matching HEAD */
+	git_repository_index(&index, repo);
+
+	idx_entry.mode = 0100644;
+	idx_entry.path = "veal.txt";
+	cl_git_pass(git_oid_fromstr(&idx_entry.id, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d"));
+
+	cl_git_pass(git_index_add(index, &idx_entry));
+	cl_git_pass(git_index_remove(index, "asparagus.txt", 0));
+	cl_git_pass(git_index_write(index));
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_WORKDIR, NULL));
+
+	validate_apply_index(repo, index_expected, index_expected_cnt);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_index_free(index);
+	git_diff_free(diff);
+}
+
+void test_apply_workdir__application_failure_leaves_workdir_unmodified(void)
+{
+	git_diff *diff;
+
+	const char *diff_file = DIFF_MODIFY_TWO_FILES;
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "8684724651336001c5dbce74bed6736d2443958d", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+		sizeof(struct merge_index_entry);
+
+	/* mutate the workdir */
+	cl_git_rewritefile("merge-recursive/veal.txt",
+	    "This is a modification.\n");
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_fail_with(GIT_EAPPLYFAIL, git_apply(repo, diff, GIT_APPLY_LOCATION_WORKDIR, NULL));
+
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_workdir__keeps_nonconflicting_changes(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "f75ba05f340c51065cbea2e1fdbfe5fe13144c97", 0, "gravy.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+	    sizeof(struct merge_index_entry);
+
+	cl_git_rmfile("merge-recursive/oyster.txt");
+	cl_git_rewritefile("merge-recursive/gravy.txt", "Hello, world.\n");
+
+	cl_git_pass(git_diff_from_buffer(&diff,
+		DIFF_MODIFY_TWO_FILES, strlen(DIFF_MODIFY_TWO_FILES)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_WORKDIR, NULL));
+
+	validate_index_unchanged(repo);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_workdir__can_apply_nonconflicting_file_changes(void)
+{
+	git_diff *diff;
+
+	const char *diff_file = DIFF_MODIFY_TWO_FILES;
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "5db1a0fef164cb66cc0c00d35cc5af979ddc1a64", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "a7b066537e6be7109abfe4ff97b675d4e077da20", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+		sizeof(struct merge_index_entry);
+
+	/*
+	 * Replace the workdir file with a version that is different than
+	 * HEAD but such that the patch still applies cleanly.  This item
+	 * has a new line appended.
+	 */
+	cl_git_append2file("merge-recursive/asparagus.txt",
+	    "This line is added in the workdir.\n");
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_WORKDIR, NULL));
+
+	validate_index_unchanged(repo);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_workdir__change_mode(void)
+{
+#ifndef GIT_WIN32
+	git_diff *diff;
+
+	const char *diff_file = DIFF_EXECUTABLE_FILE;
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100755, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, diff_file, strlen(diff_file)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_WORKDIR, NULL));
+
+	validate_index_unchanged(repo);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+#endif
+}
+
+void test_apply_workdir__apply_many_changes_one(void)
+{
+	git_diff *diff;
+	git_apply_options opts = GIT_APPLY_OPTIONS_INIT;
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "c9d7d5d58088bc91f6e06f17ca3a205091568d3a", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+	    sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff,
+		DIFF_MANY_CHANGES_ONE, strlen(DIFF_MANY_CHANGES_ONE)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_WORKDIR, &opts));
+
+	validate_index_unchanged(repo);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+}
+
+void test_apply_workdir__apply_many_changes_two(void)
+{
+	git_diff *diff;
+	git_apply_options opts = GIT_APPLY_OPTIONS_INIT;
+
+	struct merge_index_entry workdir_expected[] = {
+		{ 0100644, "f51658077d85f2264fa179b4d0848268cb3475c3", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "6b943d65af6d8db74d747284fa4ca7d716ad5bbb", 0, "veal.txt" },
+	};
+	size_t workdir_expected_cnt = sizeof(workdir_expected) /
+	    sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff,
+		DIFF_MANY_CHANGES_TWO, strlen(DIFF_MANY_CHANGES_TWO)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_WORKDIR, &opts));
+
+	validate_index_unchanged(repo);
+	validate_apply_workdir(repo, workdir_expected, workdir_expected_cnt);
+
+	git_diff_free(diff);
+}
diff --git a/tests/iterator/workdir.c b/tests/iterator/workdir.c
index a16acd7..889fcd6 100644
--- a/tests/iterator/workdir.c
+++ b/tests/iterator/workdir.c
@@ -3,6 +3,7 @@
 #include "repository.h"
 #include "fileops.h"
 #include "../submodule/submodule_helpers.h"
+#include "../merge/merge_helpers.h"
 #include "iterator_helpers.h"
 #include <stdarg.h>
 
@@ -1474,3 +1475,48 @@ void test_iterator_workdir__pathlist_with_directory_include_trees(void)
 	git_vector_free(&filelist);
 }
 
+void test_iterator_workdir__hash_when_requested(void)
+{
+	git_iterator *iter;
+	const git_index_entry *entry;
+	git_iterator_options iter_opts = GIT_ITERATOR_OPTIONS_INIT;
+	git_oid expected_id = {{0}};
+	size_t i;
+
+	struct merge_index_entry expected[] = {
+		{ 0100644, "ffb36e513f5fdf8a6ba850a20142676a2ac4807d", 0, "asparagus.txt" },
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "beef.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "7c7e08f9559d9e1551b91e1cf68f1d0066109add", 0, "oyster.txt" },
+		{ 0100644, "898d12687fb35be271c27c795a6b32c8b51da79e", 0, "veal.txt" },
+	};
+
+	g_repo = cl_git_sandbox_init("merge-recursive");
+
+	/* do the iteration normally, ensure there are no hashes */
+	cl_git_pass(git_iterator_for_workdir(&iter, g_repo, NULL, NULL, &iter_opts));
+
+	for (i = 0; i < sizeof(expected) / sizeof(struct merge_index_entry); i++) {
+		cl_git_pass(git_iterator_advance(&entry, iter));
+
+		cl_assert_equal_oid(&expected_id, &entry->id);
+		cl_assert_equal_s(expected[i].path, entry->path);
+	}
+	cl_assert_equal_i(GIT_ITEROVER, git_iterator_advance(&entry, iter));
+	git_iterator_free(iter);
+
+	/* do the iteration requesting hashes */
+	iter_opts.flags |= GIT_ITERATOR_INCLUDE_HASH;
+	cl_git_pass(git_iterator_for_workdir(&iter, g_repo, NULL, NULL, &iter_opts));
+
+	for (i = 0; i < sizeof(expected) / sizeof(struct merge_index_entry); i++) {
+		cl_git_pass(git_iterator_advance(&entry, iter));
+
+		cl_git_pass(git_oid_fromstr(&expected_id, expected[i].oid_str));
+		cl_assert_equal_oid(&expected_id, &entry->id);
+		cl_assert_equal_s(expected[i].path, entry->path);
+	}
+	cl_assert_equal_i(GIT_ITEROVER, git_iterator_advance(&entry, iter));
+	git_iterator_free(iter);
+}
diff --git a/tests/patch/patch_common.h b/tests/patch/patch_common.h
index e838e60..3f2668d 100644
--- a/tests/patch/patch_common.h
+++ b/tests/patch/patch_common.h
@@ -220,6 +220,112 @@
 	"@@ -0,0 +1 @@\n" \
 	"+insert at front\n"
 
+/* An insertion at the beginning of the file and change in the middle */
+
+#define FILE_PREPEND_AND_CHANGE \
+	"insert at front\n" \
+	"hey!\n" \
+	"this is some context!\n" \
+	"around some lines\n" \
+	"that will change\n" \
+	"yes it is!\n" \
+	"(THIS line is changed!)\n" \
+	"and this\n" \
+	"is additional context\n" \
+	"below it!\n"
+
+#define PATCH_ORIGINAL_TO_PREPEND_AND_CHANGE \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..f73c8bb 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -1,9 +1,10 @@\n" \
+	"+insert at front\n" \
+	" hey!\n" \
+	" this is some context!\n" \
+	" around some lines\n" \
+	" that will change\n" \
+	" yes it is!\n" \
+	"-(this line is changed)\n" \
+	"+(THIS line is changed!)\n" \
+	" and this\n" \
+	" is additional context\n" \
+	" below it!\n"
+
+#define PATCH_ORIGINAL_TO_PREPEND_AND_CHANGE_NOCONTEXT \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..f73c8bb 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -0,0 +1 @@\n" \
+	"+insert at front\n" \
+	"@@ -6 +7 @@ yes it is!\n" \
+	"-(this line is changed)\n" \
+	"+(THIS line is changed!)\n"
+
+/* A deletion at the beginning of the file and a change in the middle */
+
+#define FILE_DELETE_AND_CHANGE \
+	"this is some context!\n" \
+	"around some lines\n" \
+	"that will change\n" \
+	"yes it is!\n" \
+	"(THIS line is changed!)\n" \
+	"and this\n" \
+	"is additional context\n" \
+	"below it!\n"
+
+#define PATCH_ORIGINAL_TO_DELETE_AND_CHANGE \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..1e2dfa6 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -1,9 +1,8 @@\n" \
+	"-hey!\n" \
+	" this is some context!\n" \
+	" around some lines\n" \
+	" that will change\n" \
+	" yes it is!\n" \
+	"-(this line is changed)\n" \
+	"+(THIS line is changed!)\n" \
+	" and this\n" \
+	" is additional context\n" \
+	" below it!\n"
+
+#define PATCH_ORIGINAL_TO_DELETE_AND_CHANGE_NOCONTEXT \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..1e2dfa6 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -1 +0,0 @@\n" \
+	"-hey!\n" \
+	"@@ -6 +5 @@ yes it is!\n" \
+	"-(this line is changed)\n" \
+	"+(THIS line is changed!)\n"
+
+/* A deletion at the beginning of the file */
+
+#define FILE_DELETE_FIRSTLINE \
+	"this is some context!\n" \
+	"around some lines\n" \
+	"that will change\n" \
+	"yes it is!\n" \
+	"(this line is changed)\n" \
+	"and this\n" \
+	"is additional context\n" \
+	"below it!\n"
+
+#define PATCH_ORIGINAL_TO_DELETE_FIRSTLINE \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..f31fa13 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -1,4 +1,3 @@\n" \
+	"-hey!\n" \
+	" this is some context!\n" \
+	" around some lines\n" \
+	" that will change\n"
+
 /* An insertion at the end of the file (and the resultant patch) */
 
 #define FILE_APPEND \
diff --git a/tests/resources/merge-recursive/.gitted/objects/06/d3fefb8726ab1099acc76e02dfb85e034b2538 b/tests/resources/merge-recursive/.gitted/objects/06/d3fefb8726ab1099acc76e02dfb85e034b2538
new file mode 100644
index 0000000..b3919aa
Binary files /dev/null and b/tests/resources/merge-recursive/.gitted/objects/06/d3fefb8726ab1099acc76e02dfb85e034b2538 differ