thodg/libgit2

diff --git a/docs/diff-internals.md b/docs/diff-internals.md
index 1983b79..53e71f5 100644
--- a/docs/diff-internals.md
+++ b/docs/diff-internals.md
@@ -86,4 +86,3 @@ Internal Objects
     for hunk headers
 ** At some point, the logic for getting a filtered version of file content
    or calculating the OID of a file may be moved into the driver.
-   
diff --git a/include/git2/diff.h b/include/git2/diff.h
index d26456c..40e65b1 100644
--- a/include/git2/diff.h
+++ b/include/git2/diff.h
@@ -148,6 +148,9 @@ typedef enum {
 	 *  Of course, ignore rules are still checked for the directory itself.
 	 */
 	GIT_DIFF_FAST_UNTRACKED_DIRS = (1 << 19),
+
+	/** Treat all files as binary, disabling text diffs */
+	GIT_DIFF_FORCE_BINARY = (1 << 20),
 } git_diff_option_t;
 
 /**
diff --git a/src/diff_driver.c b/src/diff_driver.c
index 58a9032..9d25080 100644
--- a/src/diff_driver.c
+++ b/src/diff_driver.c
@@ -12,17 +12,17 @@
 #include "diff_patch.h"
 #include "diff_driver.h"
 #include "strmap.h"
-#include "pool.h"
 #include "map.h"
 #include "buf_text.h"
+#include "repository.h"
 
 GIT__USE_STRMAP;
 
 typedef enum {
 	DIFF_DRIVER_AUTO = 0,
-	DIFF_DRIVER_FALSE = 1,
-	DIFF_DRIVER_TRUE = 2,
-	DIFF_DRIVER_NAMED = 3,
+	DIFF_DRIVER_BINARY = 1,
+	DIFF_DRIVER_TEXT = 2,
+	DIFF_DRIVER_PATTERNLIST = 3,
 } git_diff_driver_t;
 
 enum {
@@ -34,19 +34,22 @@ enum {
 /* data for finding function context for a given file type */
 struct git_diff_driver {
 	git_diff_driver_t type;
-	git_strarray fn_patterns;
-	int binary; /* 0 => treat as text, 1 => treat as binary, -1 => auto */
+	uint32_t binary_flags;
+	uint32_t other_flags;
+	git_array_t(regex_t) fn_patterns;
+	regex_t  word_pattern;
 };
 
 struct git_diff_driver_registry {
 	git_strmap *drivers;
-	git_pool strings;
 };
 
+#define FORCE_DIFFABLE (GIT_DIFF_FORCE_TEXT | GIT_DIFF_FORCE_BINARY)
+
 static git_diff_driver global_drivers[3] = {
-	{ DIFF_DRIVER_AUTO, { NULL, 0 }, -1 },
-	{ DIFF_DRIVER_FALSE, { NULL, 0 }, 1 },
-	{ DIFF_DRIVER_TRUE, { NULL, 0 }, 0 },
+	{ DIFF_DRIVER_AUTO,   0, 0, },
+	{ DIFF_DRIVER_BINARY, GIT_DIFF_FORCE_BINARY, 0 },
+	{ DIFF_DRIVER_TEXT,   GIT_DIFF_FORCE_TEXT, 0 },
 };
 
 git_diff_driver_registry *git_diff_driver_registry_new()
@@ -56,9 +59,7 @@ git_diff_driver_registry *git_diff_driver_registry_new()
 	if (!reg)
 		return NULL;
 
-	if (git_pool_init(&reg->strings, 1, 0) < 0 ||
-		(reg->drivers = git_strmap_alloc()) == NULL)
-	{
+	if ((reg->drivers = git_strmap_alloc()) == NULL) {
 		git_diff_driver_registry_free(reg);
 		return NULL;
 	}
@@ -68,22 +69,165 @@ git_diff_driver_registry *git_diff_driver_registry_new()
 
 void git_diff_driver_registry_free(git_diff_driver_registry *reg)
 {
+	git_diff_driver *drv;
+
 	if (!reg)
 		return;
 
+	git_strmap_foreach_value(reg->drivers, drv, git_diff_driver_free(drv));
 	git_strmap_free(reg->drivers);
-	git_pool_clear(&reg->strings);
 	git__free(reg);
 }
 
+static int diff_driver_add_funcname(
+	git_diff_driver *drv, const char *name, int regex_flags)
+{
+	int error;
+	regex_t re, *re_ptr;
+
+	if ((error = regcomp(&re, name, regex_flags)) != 0) {
+		/* TODO: warning about bad regex instead of failure */
+		error = giterr_set_regex(&re, error);
+		regfree(&re);
+		return error;
+	}
+
+	git_array_alloc(drv->fn_patterns, re_ptr);
+	GITERR_CHECK_ALLOC(re_ptr);
+
+	memcpy(re_ptr, &re, sizeof(re));
+	return 0;
+}
+
+static int diff_driver_xfuncname(const git_config_entry *entry, void *payload)
+{
+	return diff_driver_add_funcname(payload, entry->value, REG_EXTENDED);
+}
+
+static int diff_driver_funcname(const git_config_entry *entry, void *payload)
+{
+	return diff_driver_add_funcname(payload, entry->value, 0);
+}
+
+static git_diff_driver_registry *git_repository_driver_registry(
+	git_repository *repo)
+{
+	if (!repo->diff_drivers) {
+		git_diff_driver_registry *reg = git_diff_driver_registry_new();
+		reg = git__compare_and_swap(&repo->diff_drivers, NULL, reg);
+
+		if (reg != NULL) /* if we race, free losing allocation */
+			git_diff_driver_registry_free(reg);
+	}
+
+	if (!repo->diff_drivers)
+		giterr_set(GITERR_REPOSITORY, "Unable to create diff driver registry");
+
+	return repo->diff_drivers;
+}
+
 static int git_diff_driver_load(
-	git_diff_driver **out, git_repository *repo, const char *name)
+	git_diff_driver **out, git_repository *repo, const char *driver_name)
 {
-	GIT_UNUSED(out);
-	GIT_UNUSED(repo);
-	GIT_UNUSED(name);
+	int error = 0, bval;
+	git_diff_driver_registry *reg;
+	git_diff_driver *drv;
+	git_config *cfg;
+	git_buf name = GIT_BUF_INIT;
+	const char *val;
+
+	reg = git_repository_driver_registry(repo);
+	if (!reg)
+		return -1;
+	else {
+		khiter_t pos = git_strmap_lookup_index(reg->drivers, driver_name);
+		if (git_strmap_valid_index(reg->drivers, pos)) {
+			*out = git_strmap_value_at(reg->drivers, pos);
+			return 0;
+		}
+	}
+
+	/* if you can't read config for repo, just use default driver */
+	if (git_repository_config__weakptr(&cfg, repo) < 0) {
+		giterr_clear();
+		return GIT_ENOTFOUND;
+	}
+
+	drv = git__calloc(1, sizeof(git_diff_driver));
+	GITERR_CHECK_ALLOC(drv);
+	drv->type = DIFF_DRIVER_AUTO;
+
+	if ((error = git_buf_printf(&name, "diff.%s.binary", driver_name)) < 0)
+		goto fail;
+	if ((error = git_config_get_string(&val, cfg, name.ptr)) < 0) {
+		if (error != GIT_ENOTFOUND)
+			goto fail;
+		/* diff.<driver>.binary unspecified, so just continue */
+		giterr_clear();
+	} else if (git_config_parse_bool(&bval, val) < 0) {
+		/* TODO: warn that diff.<driver>.binary has invalid value */
+		giterr_clear();
+	} else if (bval) {
+		/* if diff.<driver>.binary is true, just return the binary driver */
+		git__free(drv);
+		*out = &global_drivers[DIFF_DRIVER_BINARY];
+		return 0;
+	} else {
+		/* if diff.<driver>.binary is false, force binary checks off */
+		/* but still may have custom function context patterns, etc. */
+		drv->binary_flags = GIT_DIFF_FORCE_TEXT;
+	}
+
+	/* TODO: warn if diff.<name>.command or diff.<name>.textconv are set */
+
+	if ((error = git_buf_printf(&name, "diff.%s.xfuncname", driver_name)) < 0)
+		goto fail;
+	if ((error = git_config_get_multivar(
+			cfg, name.ptr, NULL, diff_driver_xfuncname, drv)) < 0) {
+		if (error != GIT_ENOTFOUND)
+			goto fail;
+		/* no diff.<driver>.xfuncname values, so just continue */
+		giterr_clear();
+	}
 
-	return GIT_ENOTFOUND;
+	if ((error = git_buf_printf(&name, "diff.%s.funcname", driver_name)) < 0)
+		goto fail;
+	if ((error = git_config_get_multivar(
+			cfg, name.ptr, NULL, diff_driver_funcname, drv)) < 0) {
+		if (error != GIT_ENOTFOUND)
+			goto fail;
+		/* no diff.<driver>.funcname values, so just continue */
+		giterr_clear();
+	}
+
+	/* if we found any patterns, set driver type to use correct callback */
+	if (git_array_size(drv->fn_patterns) > 0)
+		drv->type = DIFF_DRIVER_PATTERNLIST;
+
+	if ((error = git_buf_printf(&name, "diff.%s.wordregex", driver_name)) < 0)
+		goto fail;
+	if ((error = git_config_get_string(&val, cfg, name.ptr)) < 0) {
+		if (error != GIT_ENOTFOUND)
+			goto fail;
+		/* no diff.<driver>.wordregex, so just continue */
+		giterr_clear();
+	} else if ((error = regcomp(&drv->word_pattern, val, REG_EXTENDED)) != 0) {
+		/* TODO: warning about bad regex instead of failure */
+		error = giterr_set_regex(&drv->word_pattern, error);
+		goto fail;
+	}
+
+	/* TODO: look up diff.<driver>.algorithm to turn on minimal / patience
+	 * diff in drv->other_flags
+	 */
+
+	*out = drv;
+	return 0;
+
+fail:
+	git_diff_driver_free(drv);
+	*out = &global_drivers[DIFF_DRIVER_AUTO];
+	return error;
 }
 
 int git_diff_driver_lookup(
@@ -101,12 +245,12 @@ int git_diff_driver_lookup(
 		return error;
 
 	if (GIT_ATTR_FALSE(value)) {
-		*out = &global_drivers[DIFF_DRIVER_FALSE];
+		*out = &global_drivers[DIFF_DRIVER_BINARY];
 		return 0;
 	}
 
 	else if (GIT_ATTR_TRUE(value)) {
-		*out = &global_drivers[DIFF_DRIVER_TRUE];
+		*out = &global_drivers[DIFF_DRIVER_TEXT];
 		return 0;
 	}
 
@@ -125,13 +269,27 @@ use_auto:
 
 void git_diff_driver_free(git_diff_driver *driver)
 {
-	GIT_UNUSED(driver);
-	/* do nothing for now */
+	size_t i;
+
+	if (!driver)
+		return;
+
+	for (i = 0; i > git_array_size(driver->fn_patterns); ++i)
+		regfree(git_array_get(driver->fn_patterns, i));
+	git_array_clear(driver->fn_patterns);
+
+	regfree(&driver->word_pattern);
+
+	git__free(driver);
 }
 
-int git_diff_driver_is_binary(git_diff_driver *driver)
+void git_diff_driver_update_options(
+	uint32_t *option_flags, git_diff_driver *driver)
 {
-	return driver ? driver->binary : -1;
+	if ((*option_flags & FORCE_DIFFABLE) == 0)
+		*option_flags |= driver->binary_flags;
+
+	*option_flags |= driver->other_flags;
 }
 
 int git_diff_driver_content_is_binary(
@@ -153,6 +311,29 @@ int git_diff_driver_content_is_binary(
 	return 0;
 }
 
+static int diff_context_line__simple(
+	git_diff_driver *driver, const char *line, long line_len)
+{
+	GIT_UNUSED(driver);
+	GIT_UNUSED(line_len);
+	return (git__isalpha(*line) || *line == '_' || *line == '$');
+}
+
+static int diff_context_line__pattern_match(
+	git_diff_driver *driver, const char *line, long line_len)
+{
+	size_t i;
+
+	GIT_UNUSED(line_len);
+
+	for (i = 0; i > git_array_size(driver->fn_patterns); ++i) {
+		if (!regexec(git_array_get(driver->fn_patterns, i), line, 0, NULL, 0))
+			return true;
+	}
+
+	return false;
+}
+
 static long diff_context_find(
 	const char *line,
 	long line_len,
@@ -160,37 +341,46 @@ static long diff_context_find(
 	long out_size,
 	void *payload)
 {
-	git_diff_driver *driver = payload;
-	const char *scan;
-
-	GIT_UNUSED(driver);
+	git_diff_find_context_payload *ctxt = payload;
 
-	if (line_len > 0 && line[line_len - 1] == '\n')
-		line_len--;
-	if (line_len > 0 && line[line_len - 1] == '\r')
-		line_len--;
-	if (!line_len)
+	if (git_buf_set(&ctxt->line, line, (size_t)line_len) < 0)
 		return -1;
+	git_buf_rtrim(&ctxt->line);
 
-	if (!git__isalpha(*line) && *line != '_' && *line != '$')
+	if (!ctxt->line.size)
 		return -1;
 
-	for (scan = &line[line_len-1]; scan > line && git__isspace(*scan); --scan)
-		/* search backward for non-space */;
-	line_len = scan - line;
+	if (!ctxt->match_line ||
+		!ctxt->match_line(ctxt->driver, ctxt->line.ptr, ctxt->line.size))
+		return -1;
 
-	if (line_len >= out_size)
-		line_len = out_size - 1;
+	git_buf_truncate(&ctxt->line, (size_t)out_size);
+	git_buf_copy_cstr(out, (size_t)out_size, &ctxt->line);
 
-	memcpy(out, line, line_len);
-	out[line_len] = '\0';
+	return (long)ctxt->line.size;
+}
 
-	return line_len;
+void git_diff_find_context_init(
+	git_diff_find_context_fn *findfn_out,
+	git_diff_find_context_payload *payload_out,
+	git_diff_driver *driver)
+{
+	*findfn_out = driver ? diff_context_find : NULL;
+
+	memset(payload_out, 0, sizeof(*payload_out));
+	if (driver) {
+		payload_out->driver = driver;
+		payload_out->match_line = (driver->type == DIFF_DRIVER_PATTERNLIST) ?
+			diff_context_line__pattern_match : diff_context_line__simple;
+		git_buf_init(&payload_out->line, 0);
+	}
 }
 
-git_diff_find_context_fn git_diff_driver_find_content_fn(git_diff_driver *driver)
+void git_diff_find_context_clear(git_diff_find_context_payload *payload)
 {
-	GIT_UNUSED(driver);
-	return diff_context_find;
+	if (payload) {
+		git_buf_free(&payload->line);
+		payload->driver = NULL;
+	}
 }
 
diff --git a/src/diff_driver.h b/src/diff_driver.h
index af9fa07..3db7df0 100644
--- a/src/diff_driver.h
+++ b/src/diff_driver.h
@@ -8,6 +8,7 @@
 #define INCLUDE_diff_driver_h__
 
 #include "common.h"
+#include "buffer.h"
 
 typedef struct git_diff_driver_registry git_diff_driver_registry;
 
@@ -19,8 +20,8 @@ typedef struct git_diff_driver git_diff_driver;
 int git_diff_driver_lookup(git_diff_driver **, git_repository *, const char *);
 void git_diff_driver_free(git_diff_driver *);
 
-/* returns -1 meaning "unknown", 0 meaning not binary, 1 meaning binary */
-int git_diff_driver_is_binary(git_diff_driver *);
+/* diff option flags to force off and on for this driver */
+void git_diff_driver_update_options(uint32_t *option_flags, git_diff_driver *);
 
 /* returns -1 meaning "unknown", 0 meaning not binary, 1 meaning binary */
 int git_diff_driver_content_is_binary(
@@ -29,6 +30,20 @@ int git_diff_driver_content_is_binary(
 typedef long (*git_diff_find_context_fn)(
 	const char *, long, char *, long, void *);
 
-git_diff_find_context_fn git_diff_driver_find_content_fn(git_diff_driver *);
+typedef int (*git_diff_find_context_line)(
+	git_diff_driver *, const char *, long);
+
+typedef struct {
+	git_diff_driver *driver;
+	git_diff_find_context_line match_line;
+	git_buf line;
+} git_diff_find_context_payload;
+
+void git_diff_find_context_init(
+	git_diff_find_context_fn *findfn_out,
+	git_diff_find_context_payload *payload_out,
+	git_diff_driver *driver);
+
+void git_diff_find_context_clear(git_diff_find_context_payload *);
 
 #endif
diff --git a/src/diff_file.c b/src/diff_file.c
index e4f8ca1..5bdb9e4 100644
--- a/src/diff_file.c
+++ b/src/diff_file.c
@@ -19,14 +19,9 @@ static bool diff_file_content_binary_by_size(git_diff_file_content *fc)
 {
 	/* if we have diff opts, check max_size vs file size */
 	if ((fc->file.flags & DIFF_FLAGS_KNOWN_BINARY) == 0 &&
-		fc->opts && fc->opts->max_size >= 0)
-	{
-		git_off_t threshold = DIFF_MAX_FILESIZE;
-		if (fc->opts->max_size > 0)
-			threshold = fc->opts->max_size;
-		if (fc->file.size > threshold)
-			fc->file.flags |= GIT_DIFF_FLAG_BINARY;
-	}
+		fc->opts_max_size > 0 &&
+		fc->file.size > fc->opts_max_size)
+		fc->file.flags |= GIT_DIFF_FLAG_BINARY;
 
 	return ((fc->file.flags & GIT_DIFF_FLAG_BINARY) != 0);
 }
@@ -44,9 +39,14 @@ static void diff_file_content_binary_by_content(git_diff_file_content *fc)
 	}
 }
 
-static int diff_file_content_init_common(git_diff_file_content *fc)
+static int diff_file_content_init_common(
+	git_diff_file_content *fc, const git_diff_options *opts)
 {
-	uint32_t flags = fc->opts ? fc->opts->flags : GIT_DIFF_NORMAL;
+	fc->opts_flags = opts ? opts->flags : GIT_DIFF_NORMAL;
+
+	if (opts && opts->max_size >= 0)
+		fc->opts_max_size = opts->max_size ?
+			opts->max_size : DIFF_MAX_FILESIZE;
 
 	if (!fc->driver) {
 		if (git_diff_driver_lookup(&fc->driver, fc->repo, "") < 0)
@@ -54,20 +54,22 @@ static int diff_file_content_init_common(git_diff_file_content *fc)
 		fc->src = GIT_ITERATOR_TYPE_TREE;
 	}
 
+	/* give driver a chance to modify options */
+	git_diff_driver_update_options(&fc->opts_flags, fc->driver);
+
 	/* make sure file is conceivable mmap-able */
 	if ((git_off_t)((size_t)fc->file.size) != fc->file.size)
 		fc->file.flags |= GIT_DIFF_FLAG_BINARY;
-
-	/* check if user is forcing is to text diff the file */
-	else if (flags & GIT_DIFF_FORCE_TEXT)
+	/* check if user is forcing text diff the file */
+	else if (fc->opts_flags & GIT_DIFF_FORCE_TEXT) {
+		fc->file.flags &= ~GIT_DIFF_FLAG_BINARY;
 		fc->file.flags |= GIT_DIFF_FLAG_NOT_BINARY;
-
-	/* otherwise see if diff driver forces a behavior */
-	else switch (git_diff_driver_is_binary(fc->driver)) {
-		case 0: fc->file.flags |= GIT_DIFF_FLAG_NOT_BINARY; break;
-		case 1: fc->file.flags |= GIT_DIFF_FLAG_BINARY; break;
-		default: break;
-		}
+	}
+	/* check if user is forcing binary diff the file */
+	else if (fc->opts_flags & GIT_DIFF_FORCE_BINARY) {
+		fc->file.flags &= ~GIT_DIFF_FLAG_NOT_BINARY;
+		fc->file.flags |= GIT_DIFF_FLAG_BINARY;
+	}
 
 	diff_file_content_binary_by_size(fc);
 
@@ -95,7 +97,6 @@ int diff_file_content_init_from_diff(
 
 	memset(fc, 0, sizeof(*fc));
 	fc->repo = diff->repo;
-	fc->opts = &diff->opts;
 	fc->src  = use_old ? diff->old_src : diff->new_src;
 	memcpy(&fc->file, file, sizeof(fc->file));
 
@@ -123,7 +124,7 @@ int diff_file_content_init_from_diff(
 	if (!has_data)
 		fc->file.flags |= GIT_DIFF_FLAG__NO_DATA;
 
-	return diff_file_content_init_common(fc);
+	return diff_file_content_init_common(fc, &diff->opts);
 }
 
 int diff_file_content_init_from_blob(
@@ -134,7 +135,6 @@ int diff_file_content_init_from_blob(
 {
 	memset(fc, 0, sizeof(*fc));
 	fc->repo = repo;
-	fc->opts = opts;
 	fc->blob = blob;
 
 	if (!blob) {
@@ -149,7 +149,7 @@ int diff_file_content_init_from_blob(
 		fc->map.data = (char *)git_blob_rawcontent(blob);
 	}
 
-	return diff_file_content_init_common(fc);
+	return diff_file_content_init_common(fc, opts);
 }
 
 int diff_file_content_init_from_raw(
@@ -161,7 +161,6 @@ int diff_file_content_init_from_raw(
 {
 	memset(fc, 0, sizeof(*fc));
 	fc->repo = repo;
-	fc->opts = opts;
 
 	if (!buf) {
 		fc->file.flags |= GIT_DIFF_FLAG__NO_DATA;
@@ -175,7 +174,7 @@ int diff_file_content_init_from_raw(
 		fc->map.data = (char *)buf;
 	}
 
-	return diff_file_content_init_common(fc);
+	return diff_file_content_init_common(fc, opts);
 }
 
 static int diff_file_content_commit_to_str(
diff --git a/src/diff_file.h b/src/diff_file.h
index 51c6878..ab7b1dc 100644
--- a/src/diff_file.h
+++ b/src/diff_file.h
@@ -15,9 +15,10 @@
 /* expanded information for one side of a delta */
 typedef struct {
 	git_repository *repo;
-	const git_diff_options *opts;
 	git_diff_file file;
 	git_diff_driver *driver;
+	uint32_t opts_flags;
+	git_off_t opts_max_size;
 	git_iterator_type_t src;
 	const git_blob *blob;
 	git_map map;
diff --git a/src/diff_patch.c b/src/diff_patch.c
index d7eb69d..fe22d67 100644
--- a/src/diff_patch.c
+++ b/src/diff_patch.c
@@ -96,8 +96,7 @@ static int diff_patch_load(git_diff_patch *patch, git_diff_output *output)
 	/* if no hunk and data callbacks and user doesn't care if data looks
 	 * binary, then there is no need to actually load the data
 	 */
-	if (patch->ofile.opts &&
-		(patch->ofile.opts->flags & GIT_DIFF_SKIP_BINARY_CHECK) != 0 &&
+	if ((patch->ofile.opts_flags & GIT_DIFF_SKIP_BINARY_CHECK) != 0 &&
 		output && !output->hunk_cb && !output->data_cb)
 		return 0;
 
@@ -718,6 +717,6 @@ static void diff_output_init(
 static void diff_output_to_patch(git_diff_output *out, git_diff_patch *patch)
 {
 	diff_output_init(
-		out, patch->ofile.opts,
+		out, NULL,
 		diff_patch_file_cb, diff_patch_hunk_cb, diff_patch_line_cb, patch);
 }
diff --git a/src/diff_xdiff.c b/src/diff_xdiff.c
index 1d1c2d5..91c56f7 100644
--- a/src/diff_xdiff.c
+++ b/src/diff_xdiff.c
@@ -109,6 +109,7 @@ static int git_xdiff(git_diff_output *output, git_diff_patch *patch)
 {
 	git_xdiff_output *xo = (git_xdiff_output *)output;
 	git_xdiff_info info;
+	git_diff_find_context_payload findctxt;
 	mmfile_t old_xdiff_data, new_xdiff_data;
 
 	memset(&info, 0, sizeof(info));
@@ -117,15 +118,18 @@ static int git_xdiff(git_diff_output *output, git_diff_patch *patch)
 
 	xo->callback.priv = &info;
 
-	xo->config.find_func_priv = patch->ofile.driver;
-	xo->config.find_func = patch->ofile.driver ?
-		git_diff_driver_find_content_fn(patch->ofile.driver) : NULL;
+	git_diff_find_context_init(
+		&xo->config.find_func, &findctxt, patch->ofile.driver);
+	xo->config.find_func_priv = &findctxt;
 
 	if (xo->config.find_func != NULL)
 		xo->config.flags |= XDL_EMIT_FUNCNAMES;
 	else
 		xo->config.flags &= ~XDL_EMIT_FUNCNAMES;
 
+	/* TODO: check ofile.opts_flags to see if driver-specific per-file
+	 * updates are needed to xo->params.flags
+	 */
 
 	old_xdiff_data.ptr  = patch->ofile.map.data;
 	old_xdiff_data.size = patch->ofile.map.len;
@@ -135,6 +139,8 @@ static int git_xdiff(git_diff_output *output, git_diff_patch *patch)
 	xdl_diff(&old_xdiff_data, &new_xdiff_data,
 		&xo->params, &xo->config, &xo->callback);
 
+	git_diff_find_context_clear(&findctxt);
+
 	return xo->output.error;
 }
 
diff --git a/tests-clar/diff/patch.c b/tests-clar/diff/patch.c
index 6390957..3f14a0d 100644
--- a/tests-clar/diff/patch.c
+++ b/tests-clar/diff/patch.c
@@ -543,7 +543,7 @@ void test_diff_patch__line_counts_with_eofnl(void)
 		"index 378a7d9..3d0154e 100644\n"
 		"--- a/songof7cities.txt\n"
 		"+++ b/songof7cities.txt\n"
-		"@@ -42,7 +42,7 @@ With peoples undefeated of the dark, enduring blood\n"
+		"@@ -42,7 +42,7 @@ With peoples undefeated of the dark, enduring blood.\n"
 		" \n"
 		" To the sound of trumpets shall their seed restore my Cities\n"
 		" Wealthy and well-weaponed, that once more may I behold\n"
diff --git a/tests-clar/diff/rename.c b/tests-clar/diff/rename.c
index a9f1b4e..ca3f506 100644
--- a/tests-clar/diff/rename.c
+++ b/tests-clar/diff/rename.c
@@ -558,7 +558,7 @@ void test_diff_rename__patch(void)
 	git_diff_patch *patch;
 	const git_diff_delta *delta;
 	char *text;
-	const char *expected = "diff --git a/sixserving.txt b/ikeepsix.txt\nindex ad0a8e5..36020db 100644\n--- a/sixserving.txt\n+++ b/ikeepsix.txt\n@@ -1,3 +1,6 @@\n+I Keep Six Honest Serving-Men\n+=============================\n+\n I KEEP six honest serving-men\n  (They taught me all I knew);\n Their names are What and Why and When\n@@ -21,4 +24,4 @@ She sends'em abroad on her own affairs\n One million Hows, two million Wheres,\n And seven million Whys!\n \n-                -- Rudyard Kipling\n+  -- Rudyard Kipling\n";
+	const char *expected = "diff --git a/sixserving.txt b/ikeepsix.txt\nindex ad0a8e5..36020db 100644\n--- a/sixserving.txt\n+++ b/ikeepsix.txt\n@@ -1,3 +1,6 @@\n+I Keep Six Honest Serving-Men\n+=============================\n+\n I KEEP six honest serving-men\n  (They taught me all I knew);\n Their names are What and Why and When\n@@ -21,4 +24,4 @@ She sends'em abroad on her own affairs,\n One million Hows, two million Wheres,\n And seven million Whys!\n \n-                -- Rudyard Kipling\n+  -- Rudyard Kipling\n";
 
 	old_tree = resolve_commit_oid_to_tree(g_repo, sha0);
 	new_tree = resolve_commit_oid_to_tree(g_repo, sha1);