thodg/libgit2

diff --git a/include/git2.h b/include/git2.h
index 5a55bb2..1711ff8 100644
--- a/include/git2.h
+++ b/include/git2.h
@@ -30,6 +30,7 @@
 #include "git2/commit.h"
 #include "git2/tag.h"
 #include "git2/tree.h"
+#include "git2/diff.h"
 
 #include "git2/index.h"
 #include "git2/config.h"
diff --git a/include/git2/diff.h b/include/git2/diff.h
index 1d3a8d4..0f4b078 100644
--- a/include/git2/diff.h
+++ b/include/git2/diff.h
@@ -21,81 +21,126 @@
  */
 GIT_BEGIN_DECL
 
+typedef struct {
+	int context_lines;
+	int interhunk_lines;
+	int ignore_whitespace;
+	int force_text;
+	git_strarray pathspec;
+} git_diff_options;
+
+typedef struct {
+	git_status_t status;     /* value from tree.h */
+	unsigned int old_attr;
+	unsigned int new_attr;
+	git_oid      old_oid;
+	git_oid      new_oid;
+	git_blob     *old_blob;
+	git_blob     *new_blob;
+	const char   *path;
+	const char   *new_path;  /* NULL unless status is RENAMED or COPIED */
+	int          similarity; /* value from 0 to 100 */
+	int          binary;     /* diff as binary? */
+} git_diff_delta;
+
 typedef int (*git_diff_file_fn)(
 	void *cb_data,
-	const git_oid *old,
-	const char *old_path,
-	int old_mode,
-	const git_oid *new, /* hashed object if from work tree */
-	const char *new_path,
-	int new_mode);
+	git_diff_delta *delta,
+	float progress);
+
+typedef struct {
+	int old_start;
+	int old_lines;
+	int new_start;
+	int new_lines;
+} git_diff_range;
 
 typedef int (*git_diff_hunk_fn)(
 	void *cb_data,
-	int old_start,
-	int old_lines,
-	int new_start,
-	int new_lines);
+	git_diff_delta *delta,
+	git_diff_range *range,
+	const char *header,
+	size_t header_len);
 
-#define GIT_DIFF_LINE_CONTEXT  0
-#define GIT_DIFF_LINE_ADDITION 1
-#define GIT_DIFF_LINE_DELETION 2
+#define GIT_DIFF_LINE_CONTEXT	' '
+#define GIT_DIFF_LINE_ADDITION	'+'
+#define GIT_DIFF_LINE_DELETION	'-'
+#define GIT_DIFF_LINE_ADD_EOFNL '\n'
+#define GIT_DIFF_LINE_DEL_EOFNL '\0'
 
 typedef int (*git_diff_line_fn)(
 	void *cb_data,
-	int origin, /* GIT_DIFF_LINE value from above */
+	git_diff_delta *delta,
+	char line_origin, /* GIT_DIFF_LINE value from above */
 	const char *content,
 	size_t content_len);
 
-typedef struct {
-	int context_lines;
-	int interhunk_lines;
-	int ignore_whitespace;
-
-	git_diff_file_fn file_cb;
-	git_diff_hunk_fn hunk_cb;
-	git_diff_line_fn line_cb;
-	void *cb_data;
-} git_diff_opts;
-
+typedef struct git_diff_list git_diff_list;
 
-GIT_EXTERN(int) git_diff_blobs(
-	git_repository *repo,
-	git_blob *old,
-	git_blob *new,
-	git_diff_opts *options);
+/*
+ * Generate diff lists
+ */
 
-GIT_EXTERN(int) git_diff_trees(
+GIT_EXTERN(int) git_diff_tree_to_tree(
 	git_repository *repo,
+	const git_diff_options *opts,
 	git_tree *old,
 	git_tree *new,
-	git_diff_opts *options);
+	git_diff_list **diff);
 
-GIT_EXTERN(int) git_diff_index(
+GIT_EXTERN(int) git_diff_index_to_tree(
 	git_repository *repo,
+	const git_diff_options *opts,
 	git_tree *old,
-	git_diff_opts *options);
+	git_diff_list **diff);
 
-/* pass NULL for the git_tree to diff workdir against index */
-GIT_EXTERN(int) git_diff_workdir(
+GIT_EXTERN(int) git_diff_workdir_to_tree(
 	git_repository *repo,
+	const git_diff_options *opts,
 	git_tree *old,
-	git_diff_opts *options);
+	git_diff_list **diff);
 
-GIT_EXTERN(int) git_diff_workdir_file(
+GIT_EXTERN(int) git_diff_workdir_to_index(
 	git_repository *repo,
-	git_blob *old,
-	const char *path,
-	git_diff_opts *options);
+	const git_diff_options *opts,
+	git_diff_list **diff);
 
-/* pass git_objects to diff against or NULL for index.
- * can handle: blob->blob, tree->index, tree->tree
- * it will be an error if object types don't match
+GIT_EXTERN(void) git_diff_list_free(git_diff_list *diff);
+
+/*
+ * Process diff lists
  */
-/* pass git_object to diff WT against or NULL for index
- * can handle: index->wt, tree->wt, blob->wt with path
+
+GIT_EXTERN(int) git_diff_foreach(
+	git_diff_list *diff,
+	void *cb_data,
+	git_diff_file_fn file_cb,
+	git_diff_hunk_fn hunk_cb,
+	git_diff_line_fn line_cb);
+
+#ifndef _STDIO_H_
+#include <stdio.h>
+#endif
+
+GIT_EXTERN(int) git_diff_print_compact(
+	FILE *fp, git_diff_list *diff);
+
+GIT_EXTERN(int) git_diff_print_patch(
+	FILE *fp, git_diff_list *diff);
+
+/*
+ * Misc
  */
 
+GIT_EXTERN(int) git_diff_blobs(
+	git_repository *repo,
+	git_blob *old,
+	git_blob *new,
+	git_diff_options *options,
+	void *cb_data,
+	git_diff_hunk_fn hunk_cb,
+	git_diff_line_fn line_cb);
+
 GIT_END_DECL
 
 /** @} */
diff --git a/include/git2/tree.h b/include/git2/tree.h
index 95e0fdf..c338da0 100644
--- a/include/git2/tree.h
+++ b/include/git2/tree.h
@@ -316,9 +316,14 @@ GIT_EXTERN(int) git_tree_walk(git_tree *tree, git_treewalk_cb callback, int mode
 /** @} */
 
 typedef enum {
+	GIT_STATUS_UNMODIFIED = 0,
 	GIT_STATUS_ADDED = 1,
 	GIT_STATUS_DELETED = 2,
 	GIT_STATUS_MODIFIED = 3,
+    GIT_STATUS_RENAMED = 4,
+    GIT_STATUS_COPIED = 5,
+	GIT_STATUS_IGNORED = 6,
+	GIT_STATUS_UNTRACKED = 7
 } git_status_t;
 
 typedef struct {
diff --git a/src/diff.c b/src/diff.c
index 7128b7c..6cafeb2 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -7,10 +7,126 @@
 
 #include "common.h"
 #include "git2/diff.h"
+#include "diff.h"
 #include "xdiff/xdiff.h"
 #include "blob.h"
 #include <ctype.h>
 
+static git_diff_delta *new_file_delta(
+	git_diff_list *diff,
+	const git_tree_diff_data *tdiff)
+{
+	git_buf path = GIT_BUF_INIT;
+	git_diff_delta *delta = git__calloc(1, sizeof(git_diff_delta));
+
+	if (!delta) {
+		git__rethrow(GIT_ENOMEM, "Could not allocate diff record");
+		return NULL;
+	}
+
+	/* copy shared fields */
+	delta->status   = tdiff->status;
+	delta->old_attr = tdiff->old_attr;
+	delta->new_attr = tdiff->new_attr;
+	delta->old_oid  = tdiff->old_oid;
+	delta->new_oid  = tdiff->new_oid;
+
+	if (git_buf_joinpath(&path, diff->pfx.ptr, tdiff->path) < GIT_SUCCESS ||
+		(delta->path = git_buf_detach(&path)) == NULL)
+	{
+		git__free(delta);
+		git__rethrow(GIT_ENOMEM, "Could not allocate diff record path");
+		return NULL;
+	}
+
+	return delta;
+}
+
+static int tree_diff_cb(const git_tree_diff_data *ptr, void *data)
+{
+	int error;
+	git_diff_list *diff = data;
+
+	assert(S_ISDIR(ptr->old_attr) == S_ISDIR(ptr->new_attr));
+
+	if (S_ISDIR(ptr->old_attr)) {
+		git_tree *old = NULL, *new = NULL;
+		ssize_t pfx_len = diff->pfx.size;
+
+		if (!(error = git_tree_lookup(&old, diff->repo, &ptr->old_oid)) &&
+			!(error = git_tree_lookup(&new, diff->repo, &ptr->new_oid)) &&
+			!(error = git_buf_joinpath(&diff->pfx, diff->pfx.ptr, ptr->path)))
+		{
+			error = git_tree_diff(old, new, tree_diff_cb, diff);
+			git_buf_truncate(&diff->pfx, pfx_len);
+		}
+
+		git_tree_free(old);
+		git_tree_free(new);
+	} else {
+		git_diff_delta *delta = new_file_delta(diff, ptr);
+		if (delta == NULL)
+			error = GIT_ENOMEM;
+		else if ((error = git_vector_insert(&diff->files, delta)) < GIT_SUCCESS)
+			git__free(delta);
+	}
+
+	return error;
+}
+
+static git_diff_list *git_diff_list_alloc(
+	git_repository *repo, const git_diff_options *opts)
+{
+	git_diff_list *diff = git__calloc(1, sizeof(git_diff_list));
+	if (diff != NULL) {
+		if (opts != NULL) {
+			memcpy(&diff->opts, opts, sizeof(git_diff_options));
+			/* do something safer with the pathspec strarray */
+		}
+		diff->repo = repo;
+		git_buf_init(&diff->pfx, 0);
+	}
+	return diff;
+}
+
+void git_diff_list_free(git_diff_list *diff)
+{
+	if (!diff)
+		return;
+	git_buf_free(&diff->pfx);
+	git__free(diff);
+}
+
+int git_diff_tree_to_tree(
+	git_repository *repo,
+	const git_diff_options *opts,
+	git_tree *old,
+	git_tree *new,
+	git_diff_list **diff_ptr)
+{
+	int error;
+	git_diff_list *diff = git_diff_list_alloc(repo, opts);
+	if (!diff)
+		return GIT_ENOMEM;
+
+	if ((error = git_tree_diff(old, new, tree_diff_cb, diff)) == GIT_SUCCESS) {
+		git_buf_free(&diff->pfx);	/* don't need this anymore */
+		*diff_ptr = diff;
+	} else
+		git_diff_list_free(diff);
+
+	return error;
+}
+
+typedef struct {
+	git_diff_list *diff;
+	void *cb_data;
+	git_diff_hunk_fn hunk_cb;
+	git_diff_line_fn line_cb;
+	unsigned int index;
+	git_diff_delta *delta;
+} diff_info;
+
 static int read_next_int(const char **str, int *value)
 {
 	const char *scan = *str;
@@ -28,56 +144,373 @@ static int read_next_int(const char **str, int *value)
 static int diff_output_cb(void *priv, mmbuffer_t *bufs, int len)
 {
 	int err = GIT_SUCCESS;
-	git_diff_opts *opts = priv;
+	diff_info *di = priv;
+
+	if (len == 1 && di->hunk_cb) {
+		git_diff_range range = { -1, 0, -1, 0 };
 
-	if (len == 1) {
-		int ostart = -1, olen = 0, nstart = -1, nlen = 0;
 		/* expect something of the form "@@ -%d[,%d] +%d[,%d] @@" */
-		if (opts->hunk_cb && bufs[0].ptr[0] == '@') {
+		if (bufs[0].ptr[0] == '@') {
 			const char *scan = bufs[0].ptr;
-			if (!(err = read_next_int(&scan, &ostart)) && *scan == ',')
-				err = read_next_int(&scan, &olen);
-			if (!err && !(err = read_next_int(&scan, &nstart)) && *scan == ',')
-				err = read_next_int(&scan, &nlen);
-			if (!err && ostart >= 0 && nstart >= 0)
-				err = opts->hunk_cb(
-					opts->cb_data, ostart, olen, nstart, nlen);
+			if (!(err = read_next_int(&scan, &range.old_start)) && *scan == ',')
+				err = read_next_int(&scan, &range.old_lines);
+			if (!err &&
+				!(err = read_next_int(&scan, &range.new_start)) && *scan == ',')
+				err = read_next_int(&scan, &range.new_lines);
+			if (!err && range.old_start >= 0 && range.new_start >= 0)
+				err = di->hunk_cb(
+					di->cb_data, di->delta, &range, bufs[0].ptr, bufs[0].size);
 		}
 	}
-	else if (len == 2 || len == 3) {
+	else if ((len == 2 || len == 3) && di->line_cb) {
 		int origin;
+
 		/* expect " "/"-"/"+", then data, then maybe newline */
 		origin =
 			(*bufs[0].ptr == '+') ? GIT_DIFF_LINE_ADDITION :
 			(*bufs[0].ptr == '-') ? GIT_DIFF_LINE_DELETION :
 			GIT_DIFF_LINE_CONTEXT;
 
-		if (opts->line_cb)
-			err = opts->line_cb(
-				opts->cb_data, origin, bufs[1].ptr, bufs[1].size);
+		err = di->line_cb(
+			di->cb_data, di->delta, origin, bufs[1].ptr, bufs[1].size);
+
+		/* deal with adding and removing newline at EOF */
+		if (err == GIT_SUCCESS && len == 3) {
+			if (origin == GIT_DIFF_LINE_ADDITION)
+				origin = GIT_DIFF_LINE_ADD_EOFNL;
+			else
+				origin = GIT_DIFF_LINE_DEL_EOFNL;
+
+			err = di->line_cb(
+				di->cb_data, di->delta, origin, bufs[2].ptr, bufs[2].size);
+		}
 	}
 
 	return err;
 }
 
+static int set_file_is_binary(
+	git_repository *repo,
+	git_diff_delta *file,
+	mmfile_t *old,
+	mmfile_t *new)
+{
+	int error;
+	const char *value;
+
+	/* check diff attribute +, -, or 0 */
+	error = git_attr_get(repo, file->path, "diff", &value);
+	if (error != GIT_SUCCESS)
+		return error;
+
+	if (value == GIT_ATTR_TRUE) {
+		file->binary = 0;
+		return GIT_SUCCESS;
+	}
+	if (value == GIT_ATTR_FALSE) {
+		file->binary = 1;
+		return GIT_SUCCESS;
+	}
+
+	/* TODO: if value != NULL, implement diff drivers */
+	/* TODO: check if NUL byte appears in first bit */
+	GIT_UNUSED_ARG(old);
+	GIT_UNUSED_ARG(new);
+	file->binary = 0;
+	return GIT_SUCCESS;
+}
+
+int git_diff_foreach(
+	git_diff_list *diff,
+	void *data,
+	git_diff_file_fn file_cb,
+	git_diff_hunk_fn hunk_cb,
+	git_diff_line_fn line_cb)
+{
+	int error = GIT_SUCCESS;
+	diff_info di;
+	git_diff_delta *delta;
+
+	di.diff    = diff;
+	di.cb_data = data;
+	di.hunk_cb = hunk_cb;
+	di.line_cb = line_cb;
+
+	git_vector_foreach(&diff->files, di.index, delta) {
+		mmfile_t old, new;
+		xpparam_t params;
+		xdemitconf_t cfg;
+		xdemitcb_t callback;
+
+		/* map files */
+		if (hunk_cb || line_cb) {
+			/* TODO: Partial blob reading to defer loading whole blob.
+			 * I.e. I want a blob with just the first 4kb loaded, then
+			 * later on I will read the rest of the blob if needed.
+			 */
+
+			if (delta->status == GIT_STATUS_DELETED ||
+				delta->status == GIT_STATUS_MODIFIED)
+			{
+				error = git_blob_lookup(
+					&delta->old_blob, diff->repo, &delta->old_oid);
+				old.ptr = (char *)git_blob_rawcontent(delta->old_blob);
+				old.size = git_blob_rawsize(delta->old_blob);
+			} else {
+				delta->old_blob = NULL;
+				old.ptr = "";
+				old.size = 0;
+			}
+
+			if (delta->status == GIT_STATUS_ADDED ||
+				delta->status == GIT_STATUS_MODIFIED)
+			{
+				error = git_blob_lookup(
+					&delta->new_blob, diff->repo, &delta->new_oid);
+				new.ptr = (char *)git_blob_rawcontent(delta->new_blob);
+				new.size = git_blob_rawsize(delta->new_blob);
+			} else {
+				delta->new_blob = NULL;
+				new.ptr = "";
+				new.size = 0;
+			}
+		}
+
+		if (diff->opts.force_text)
+			delta->binary = 0;
+		else if ((error = set_file_is_binary(
+			diff->repo, delta, &old, &new)) < GIT_SUCCESS)
+			break;
+
+		if (file_cb != NULL) {
+			error = file_cb(data, delta, (float)di.index / diff->files.length);
+			if (error != GIT_SUCCESS)
+				break;
+		}
+
+		/* don't do hunk and line diffs if file is binary */
+		if (delta->binary)
+			continue;
+
+		/* nothing to do if we did not get a blob */
+		if (!delta->old_blob && !delta->new_blob)
+			continue;
+
+		assert(hunk_cb || line_cb);
+
+		di.delta = delta;
+
+		memset(&params, 0, sizeof(params));
+
+		memset(&cfg, 0, sizeof(cfg));
+		cfg.ctxlen = diff->opts.context_lines || 3;
+		cfg.interhunkctxlen = diff->opts.interhunk_lines || 3;
+		if (diff->opts.ignore_whitespace)
+			cfg.flags |= XDF_WHITESPACE_FLAGS;
+
+		memset(&callback, 0, sizeof(callback));
+		callback.outf = diff_output_cb;
+		callback.priv = &di;
+
+		xdl_diff(&old, &new, &params, &cfg, &callback);
+
+		git_blob_free(delta->old_blob);
+		delta->old_blob = NULL;
+
+		git_blob_free(delta->new_blob);
+		delta->new_blob = NULL;
+	}
+
+	return error;
+}
+
+
+static char pick_suffix(int mode)
+{
+	if (S_ISDIR(mode))
+		return '/';
+	else if (mode & S_IXUSR)
+		return '*';
+	else
+		return ' ';
+}
+
+static int print_compact(void *data, git_diff_delta *delta, float progress)
+{
+	FILE *fp = data;
+	char code, old_suffix, new_suffix;
+
+	GIT_UNUSED_ARG(progress);
+
+	switch (delta->status) {
+	case GIT_STATUS_ADDED: code = 'A'; break;
+	case GIT_STATUS_DELETED: code = 'D'; break;
+	case GIT_STATUS_MODIFIED: code = 'M'; break;
+	case GIT_STATUS_RENAMED: code = 'R'; break;
+	case GIT_STATUS_COPIED: code = 'C'; break;
+	case GIT_STATUS_IGNORED: code = 'I'; break;
+	case GIT_STATUS_UNTRACKED: code = '?'; break;
+	default: code = 0;
+	}
+
+	if (!code)
+		return GIT_SUCCESS;
+
+	old_suffix = pick_suffix(delta->old_attr);
+	new_suffix = pick_suffix(delta->new_attr);
+
+	if (delta->new_path != NULL)
+		fprintf(fp, "%c\t%s%c -> %s%c\n", code,
+				delta->path, old_suffix, delta->new_path, new_suffix);
+	else if (delta->old_attr != delta->new_attr)
+		fprintf(fp, "%c\t%s%c (%o -> %o)\n", code,
+				delta->path, new_suffix, delta->old_attr, delta->new_attr);
+	else
+		fprintf(fp, "%c\t%s%c\n", code, delta->path, old_suffix);
+
+	return GIT_SUCCESS;
+}
+
+int git_diff_print_compact(FILE *fp, git_diff_list *diff)
+{
+	return git_diff_foreach(diff, fp, print_compact, NULL, NULL);
+}
+
+static int print_oid_range(FILE *fp, git_diff_delta *delta)
+{
+	char start_oid[9], end_oid[9];
+	/* TODO: Determine a good actual OID range to print */
+	/* TODO: Print a real extra line here to match git diff */
+	git_oid_to_string(start_oid, sizeof(start_oid), &delta->old_oid);
+	git_oid_to_string(end_oid, sizeof(end_oid), &delta->new_oid);
+	if (delta->old_attr == delta->new_attr)
+		fprintf(fp, "index %s..%s %o\n",
+			start_oid, end_oid, delta->old_attr);
+	else
+		fprintf(fp, "index %s..%s %o %o\n",
+				start_oid, end_oid, delta->old_attr, delta->new_attr);
+	return GIT_SUCCESS;
+}
+
+static int print_patch_file(void *data, git_diff_delta *delta, float progress)
+{
+	FILE *fp = data;
+	const char *newpath = delta->new_path ? delta->new_path : delta->path;
+
+	GIT_UNUSED_ARG(progress);
+
+	if (delta->old_blob && delta->new_blob) {
+		fprintf(fp, "diff --git a/%s b/%s\n", delta->path, newpath);
+		print_oid_range(fp, delta);
+		fprintf(fp, "--- a/%s\n", delta->path);
+		fprintf(fp, "+++ b/%s\n", newpath);
+	} else if (delta->old_blob) {
+		fprintf(fp, "diff --git a/%s /dev/null\n", delta->path);
+		print_oid_range(fp, delta);
+		fprintf(fp, "--- a/%s\n", delta->path);
+		fputs("+++ /dev/null\n", fp);
+	} else if (delta->new_blob) {
+		fprintf(fp, "diff --git /dev/null b/%s\n", newpath);
+		print_oid_range(fp, delta);
+		fputs("--- /dev/null\n", fp);
+		fprintf(fp, "+++ b/%s\n", newpath);
+	}
+
+	return GIT_SUCCESS;
+}
+
+static int print_patch_hunk(
+	void *data,
+	git_diff_delta *d,
+	git_diff_range *r,
+	const char *header,
+	size_t header_len)
+{
+	FILE *fp = data;
+	GIT_UNUSED_ARG(d);
+	GIT_UNUSED_ARG(r);
+	fprintf(fp, "%.*s", (int)header_len, header);
+	return GIT_SUCCESS;
+}
+
+static int print_patch_line(
+	void *data,
+	git_diff_delta *delta,
+	char line_origin, /* GIT_DIFF_LINE value from above */
+	const char *content,
+	size_t content_len)
+{
+	FILE *fp = data;
+	GIT_UNUSED_ARG(delta);
+	if (line_origin == GIT_DIFF_LINE_ADDITION)
+		fprintf(fp, "+%.*s", (int)content_len, content);
+	else if (line_origin == GIT_DIFF_LINE_DELETION)
+		fprintf(fp, "-%.*s", (int)content_len, content);
+	else if (content_len > 0)
+		fprintf(fp, "%.*s", (int)content_len, content);
+	return GIT_SUCCESS;
+}
+
+int git_diff_print_patch(FILE *fp, git_diff_list *diff)
+{
+	return git_diff_foreach(
+		diff, fp, print_patch_file, print_patch_hunk, print_patch_line);
+}
+
 int git_diff_blobs(
 	git_repository *repo,
 	git_blob *old_blob,
 	git_blob *new_blob,
-	git_diff_opts *options)
+	git_diff_options *options,
+	void *cb_data,
+	git_diff_hunk_fn hunk_cb,
+	git_diff_line_fn line_cb)
 {
+	diff_info di;
+	git_diff_delta delta;
 	mmfile_t old, new;
 	xpparam_t params;
 	xdemitconf_t cfg;
 	xdemitcb_t callback;
 
-	assert(repo && old_blob && new_blob && options);
+	assert(repo && options);
+
+	if (old_blob) {
+		old.ptr  = (char *)git_blob_rawcontent(old_blob);
+		old.size = git_blob_rawsize(old_blob);
+	} else {
+		old.ptr  = "";
+		old.size = 0;
+	}
 
-	old.ptr  = (char *)git_blob_rawcontent(old_blob);
-	old.size = git_blob_rawsize(old_blob);
+	if (new_blob) {
+		new.ptr  = (char *)git_blob_rawcontent(new_blob);
+		new.size = git_blob_rawsize(new_blob);
+	} else {
+		new.ptr  = "";
+		new.size = 0;
+	}
 
-	new.ptr  = (char *)git_blob_rawcontent(new_blob);
-	new.size = git_blob_rawsize(new_blob);
+	/* populate a "fake" delta record */
+	delta.status = old.ptr ?
+		(new.ptr ? GIT_STATUS_MODIFIED : GIT_STATUS_DELETED) :
+		(new.ptr ? GIT_STATUS_ADDED : GIT_STATUS_UNTRACKED);
+	delta.old_attr = 0100644; /* can't know the truth from a blob alone */
+	delta.new_attr = 0100644;
+	git_oid_cpy(&delta.old_oid, git_object_id((const git_object *)old_blob));
+	git_oid_cpy(&delta.new_oid, git_object_id((const git_object *)new_blob));
+	delta.old_blob = old_blob;
+	delta.new_blob = new_blob;
+	delta.path = NULL;
+	delta.new_path = NULL;
+	delta.similarity = 0;
+	delta.binary = 0;
+
+	di.diff    = NULL;
+	di.delta   = &delta;
+	di.cb_data = cb_data;
+	di.hunk_cb = hunk_cb;
+	di.line_cb = line_cb;	
 
 	memset(&params, 0, sizeof(params));
 
@@ -89,16 +522,9 @@ int git_diff_blobs(
 
 	memset(&callback, 0, sizeof(callback));
 	callback.outf = diff_output_cb;
-	callback.priv = options;
-
-	if (options->file_cb)
-		options->file_cb(
-			options->cb_data,
-			git_object_id((const git_object *)old_blob), NULL, 010644, 
-			git_object_id((const git_object *)new_blob), NULL, 010644);
+	callback.priv = &di;
 
 	xdl_diff(&old, &new, &params, &cfg, &callback);
 
 	return GIT_SUCCESS;
 }
-
diff --git a/src/diff.h b/src/diff.h
new file mode 100644
index 0000000..1bb5c36
--- /dev/null
+++ b/src/diff.h
@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2009-2012 the libgit2 contributors
+ *
+ * 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_diff_h__
+#define INCLUDE_diff_h__
+
+#include <stdio.h>
+#include "vector.h"
+#include "buffer.h"
+
+struct git_diff_list {
+	git_repository   *repo;
+	git_diff_options opts;
+	git_buf          pfx;
+	git_vector       files;    /* vector of git_diff_file_delta */
+};
+
+#endif
+