Merge pull request #1595 from arrbee/even-more-rename-fixes

Even more rename detection fixes

examples/diff.c

@@ -84,6 +84,10 @@ static int check_uint16_param(const char *arg, const char *pattern, uint16_t *va
 	char *endptr = NULL;
 	if (strncmp(arg, pattern, len))
 		return 0;
+	if (arg[len] == '\0' && pattern[len - 1] != '=')
+		return 1;
+	if (arg[len] == '=')
+		len++;
 	strval = strtoul(arg + len, &endptr, 0);
 	if (endptr == arg)
 		return 0;
@@ -110,13 +114,20 @@ static void usage(const char *message, const char *arg)
 	exit(1);
 }
 
+enum {
+	FORMAT_PATCH = 0,
+	FORMAT_COMPACT = 1,
+	FORMAT_RAW = 2
+};
+
 int main(int argc, char *argv[])
 {
 	git_repository *repo = NULL;
 	git_tree *t1 = NULL, *t2 = NULL;
 	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
+	git_diff_find_options findopts = GIT_DIFF_FIND_OPTIONS_INIT;
 	git_diff_list *diff;
-	int i, color = -1, compact = 0, cached = 0;
+	int i, color = -1, format = FORMAT_PATCH, cached = 0;
 	char *a, *treeish1 = NULL, *treeish2 = NULL;
 	const char *dir = ".";
 
@@ -137,11 +148,13 @@ int main(int argc, char *argv[])
 		}
 		else if (!strcmp(a, "-p") || !strcmp(a, "-u") ||
 			!strcmp(a, "--patch"))
-			compact = 0;
+			format = FORMAT_PATCH;
 		else if (!strcmp(a, "--cached"))
 			cached = 1;
 		else if (!strcmp(a, "--name-status"))
-			compact = 1;
+			format = FORMAT_COMPACT;
+		else if (!strcmp(a, "--raw"))
+			format = FORMAT_RAW;
 		else if (!strcmp(a, "--color"))
 			color = 0;
 		else if (!strcmp(a, "--no-color"))
@@ -160,6 +173,20 @@ int main(int argc, char *argv[])
 			opts.flags |= GIT_DIFF_INCLUDE_IGNORED;
 		else if (!strcmp(a, "--untracked"))
 			opts.flags |= GIT_DIFF_INCLUDE_UNTRACKED;
+		else if (check_uint16_param(a, "-M", &findopts.rename_threshold) ||
+				 check_uint16_param(a, "--find-renames",
+					&findopts.rename_threshold))
+			findopts.flags |= GIT_DIFF_FIND_RENAMES;
+		else if (check_uint16_param(a, "-C", &findopts.copy_threshold) ||
+				 check_uint16_param(a, "--find-copies",
+					&findopts.copy_threshold))
+			findopts.flags |= GIT_DIFF_FIND_COPIES;
+		else if (!strcmp(a, "--find-copies-harder"))
+			findopts.flags |= GIT_DIFF_FIND_COPIES_FROM_UNMODIFIED;
+		else if (!strncmp(a, "-B", 2) || !strncmp(a, "--break-rewrites", 16)) {
+			/* TODO: parse thresholds */
+			findopts.flags |= GIT_DIFF_FIND_REWRITES;
+		}
 		else if (!check_uint16_param(a, "-U", &opts.context_lines) &&
 			!check_uint16_param(a, "--unified=", &opts.context_lines) &&
 			!check_uint16_param(a, "--inter-hunk-context=",
@@ -204,13 +231,24 @@ int main(int argc, char *argv[])
 	else
 		check(git_diff_index_to_workdir(&diff, repo, NULL, &opts), "Diff");
 
+	if ((findopts.flags & GIT_DIFF_FIND_ALL) != 0)
+		check(git_diff_find_similar(diff, &findopts),
+			"finding renames and copies ");
+
 	if (color >= 0)
 		fputs(colors[0], stdout);
 
-	if (compact)
-		check(git_diff_print_compact(diff, printer, &color), "Displaying diff");
-	else
+	switch (format) {
+	case FORMAT_PATCH:
 		check(git_diff_print_patch(diff, printer, &color), "Displaying diff");
+		break;
+	case FORMAT_COMPACT:
+		check(git_diff_print_compact(diff, printer, &color), "Displaying diff");
+		break;
+	case FORMAT_RAW:
+		check(git_diff_print_raw(diff, printer, &color), "Displaying diff");
+		break;
+	}
 
 	if (color >= 0)
 		fputs(colors[0], stdout);

include/git2/diff.h

@@ -243,6 +243,19 @@ typedef struct {
  * `NOT_BINARY` flag set to avoid examining file contents if you do not pass
  * in hunk and/or line callbacks to the diff foreach iteration function.  It
  * will just use the git attributes for those files.
+ *
+ * The similarity score is zero unless you call `git_diff_find_similar()`
+ * which does a similarity analysis of files in the diff.  Use that
+ * function to do rename and copy detection, and to split heavily modified
+ * files in add/delete pairs.  After that call, deltas with a status of
+ * GIT_DELTA_RENAMED or GIT_DELTA_COPIED will have a similarity score
+ * between 0 and 100 indicating how similar the old and new sides are.
+ *
+ * If you ask `git_diff_find_similar` to find heavily modified files to
+ * break, but to not *actually* break the records, then GIT_DELTA_MODIFIED
+ * records may have a non-zero similarity score if the self-similarity is
+ * below the split threshold.  To display this value like core Git, invert
+ * the score (a la `printf("M%03d", 100 - delta->similarity)`).
  */
 typedef struct {
 	git_diff_file old_file;
@@ -408,18 +421,28 @@ typedef enum {
 	/** consider unmodified as copy sources? (`--find-copies-harder`) */
 	GIT_DIFF_FIND_COPIES_FROM_UNMODIFIED = (1 << 3),
 
-	/** split large rewrites into delete/add pairs (`--break-rewrites=/M`) */
-	GIT_DIFF_FIND_AND_BREAK_REWRITES = (1 << 4),
+	/** mark large rewrites for split (`--break-rewrites=/M`) */
+	GIT_DIFF_FIND_REWRITES = (1 << 4),
+	/** actually split large rewrites into delete/add pairs */
+	GIT_DIFF_BREAK_REWRITES = (1 << 5),
+	/** mark rewrites for split and break into delete/add pairs */
+	GIT_DIFF_FIND_AND_BREAK_REWRITES =
+		(GIT_DIFF_FIND_REWRITES | GIT_DIFF_BREAK_REWRITES),
+
+	/** find renames/copies for untracked items in working directory */
+	GIT_DIFF_FIND_FOR_UNTRACKED = (1 << 6),
 
 	/** turn on all finding features */
-	GIT_DIFF_FIND_ALL = (0x1f),
+	GIT_DIFF_FIND_ALL = (0x0ff),
 
 	/** measure similarity ignoring leading whitespace (default) */
 	GIT_DIFF_FIND_IGNORE_LEADING_WHITESPACE = 0,
 	/** measure similarity ignoring all whitespace */
-	GIT_DIFF_FIND_IGNORE_WHITESPACE = (1 << 6),
+	GIT_DIFF_FIND_IGNORE_WHITESPACE = (1 << 12),
 	/** measure similarity including all data */
-	GIT_DIFF_FIND_DONT_IGNORE_WHITESPACE = (1 << 7),
+	GIT_DIFF_FIND_DONT_IGNORE_WHITESPACE = (1 << 13),
+	/** measure similarity only by comparing SHAs (fast and cheap) */
+	GIT_DIFF_FIND_EXACT_MATCH_ONLY = (1 << 14),
 } git_diff_find_t;
 
 /**
@@ -446,7 +469,10 @@ typedef struct {
  * - `copy_threshold` is the same as the -C option with a value
  * - `rename_from_rewrite_threshold` matches the top of the -B option
  * - `break_rewrite_threshold` matches the bottom of the -B option
- * - `target_limit` matches the -l option
+ * - `rename_limit` is the maximum number of matches to consider for
+ *   a particular file.  This is a little different from the `-l` option
+ *   to regular Git because we will still process up to this many matches
+ *   before abandoning the search.
  *
  * The `metric` option allows you to plug in a custom similarity metric.
  * Set it to NULL for the default internal metric which is based on sampling
@@ -458,21 +484,21 @@ typedef struct {
 	unsigned int version;
 
 	/** Combination of git_diff_find_t values (default FIND_RENAMES) */
-	unsigned int flags;
+	uint32_t flags;
 
 	/** Similarity to consider a file renamed (default 50) */
-	unsigned int rename_threshold;
+	uint16_t rename_threshold;
 	/** Similarity of modified to be eligible rename source (default 50) */
-	unsigned int rename_from_rewrite_threshold;
+	uint16_t rename_from_rewrite_threshold;
 	/** Similarity to consider a file a copy (default 50) */
-	unsigned int copy_threshold;
+	uint16_t copy_threshold;
 	/** Similarity to split modify into delete/add pair (default 60) */
-	unsigned int break_rewrite_threshold;
+	uint16_t break_rewrite_threshold;
 
-	/** Maximum similarity sources to examine (a la diff's `-l` option or
-	 *  the `diff.renameLimit` config) (default 200)
+	/** Maximum similarity sources to examine for a file (somewhat like
+	 *  git-diff's `-l` option or `diff.renameLimit` config) (default 200)
 	 */
-	unsigned int target_limit;
+	size_t rename_limit;
 
 	/** Pluggable similarity metric; pass NULL to use internal metric */
 	git_diff_similarity_metric *metric;
@@ -689,6 +715,22 @@ GIT_EXTERN(int) git_diff_print_compact(
 	void *payload);
 
 /**
+ * Iterate over a diff generating text output like "git diff --raw".
+ *
+ * Returning a non-zero value from the callbacks will terminate the
+ * iteration and cause this return `GIT_EUSER`.
+ *
+ * @param diff A git_diff_list generated by one of the above functions.
+ * @param print_cb Callback to make per line of diff text.
+ * @param payload Reference pointer that will be passed to your callback.
+ * @return 0 on success, GIT_EUSER on non-zero callback, or error code
+ */
+GIT_EXTERN(int) git_diff_print_raw(
+	git_diff_list *diff,
+	git_diff_data_cb print_cb,
+	void *payload);
+
+/**
  * Look up the single character abbreviation for a delta status code.
  *
  * When you call `git_diff_print_compact` it prints single letter codes into

include/git2/oid.h

@@ -90,6 +90,17 @@ GIT_EXTERN(void) git_oid_fromraw(git_oid *out, const unsigned char *raw);
 GIT_EXTERN(void) git_oid_fmt(char *out, const git_oid *id);
 
 /**
+ * Format a git_oid into a partial hex string.
+ *
+ * @param out output hex string; you say how many bytes to write.
+ *		If the number of bytes is > GIT_OID_HEXSZ, extra bytes
+ *		will be zeroed; if not, a '\0' terminator is NOT added.
+ * @param n number of characters to write into out string
+ * @param oid oid structure to format.
+ */
+GIT_EXTERN(void) git_oid_nfmt(char *out, size_t n, const git_oid *id);
+
+/**
  * Format a git_oid into a loose-object path string.
  *
  * The resulting string is "aa/...", where "aa" is the first two
@@ -117,10 +128,12 @@ GIT_EXTERN(char *) git_oid_allocfmt(const git_oid *id);
  * Format a git_oid into a buffer as a hex format c-string.
  *
  * If the buffer is smaller than GIT_OID_HEXSZ+1, then the resulting
- * oid c-string will be truncated to n-1 characters. If there are
- * any input parameter errors (out == NULL, n == 0, oid == NULL),
- * then a pointer to an empty string is returned, so that the return
- * value can always be printed.
+ * oid c-string will be truncated to n-1 characters (but will still be
+ * NUL-byte terminated).
+ *
+ * If there are any input parameter errors (out == NULL, n == 0, oid ==
+ * NULL), then a pointer to an empty string is returned, so that the
+ * return value can always be printed.
  *
  * @param out the buffer into which the oid string is output.
  * @param n the size of the out buffer.

src/checkout.c

@@ -676,33 +676,26 @@ static int buffer_to_file(
 	int file_open_flags,
 	mode_t file_mode)
 {
-	int fd, error;
+	int error;
 
 	if ((error = git_futils_mkpath2file(path, dir_mode)) < 0)
 		return error;
 
-	if ((fd = p_open(path, file_open_flags, file_mode)) < 0) {
-		giterr_set(GITERR_OS, "Could not open '%s' for writing", path);
-		return fd;
-	}
-
-	if ((error = p_write(fd, git_buf_cstr(buffer), git_buf_len(buffer))) < 0) {
-		giterr_set(GITERR_OS, "Could not write to '%s'", path);
-		(void)p_close(fd);
-	} else {
-		if ((error = p_close(fd)) < 0)
-			giterr_set(GITERR_OS, "Error while closing '%s'", path);
+	if ((error = git_futils_writebuffer(
+			buffer, path, file_open_flags, file_mode)) < 0)
+		return error;
 
-		if ((error = p_stat(path, st)) < 0)
-			giterr_set(GITERR_OS, "Error while statting '%s'", path);
+	if (st != NULL && (error = p_stat(path, st)) < 0) {
+		giterr_set(GITERR_OS, "Error while statting '%s'", path);
+		return error;
 	}
 
-	if (!error &&
-		(file_mode & 0100) != 0 &&
-		(error = p_chmod(path, file_mode)) < 0)
+	if ((file_mode & 0100) != 0 && (error = p_chmod(path, file_mode)) < 0) {
 		giterr_set(GITERR_OS, "Failed to set permissions on '%s'", path);
+		return error;
+	}
 
-	return error;
+	return 0;
 }
 
 static int blob_content_to_file(

src/diff.c

@@ -231,10 +231,23 @@ static char *diff_strdup_prefix(git_pool *pool, const char *prefix)
 		return git_pool_strndup(pool, prefix, len + 1);
 }
 
+GIT_INLINE(const char *) diff_delta__path(const git_diff_delta *delta)
+{
+	const char *str = delta->old_file.path;
+
+	if (!str ||
+		delta->status == GIT_DELTA_ADDED ||
+		delta->status == GIT_DELTA_RENAMED ||
+		delta->status == GIT_DELTA_COPIED)
+		str = delta->new_file.path;
+
+	return str;
+}
+
 int git_diff_delta__cmp(const void *a, const void *b)
 {
 	const git_diff_delta *da = a, *db = b;
-	int val = strcmp(da->old_file.path, db->old_file.path);
+	int val = strcmp(diff_delta__path(da), diff_delta__path(db));
 	return val ? val : ((int)da->status - (int)db->status);
 }
 

src/diff.h

@@ -34,10 +34,18 @@ enum {
 	GIT_DIFF_FLAG__FREE_DATA  = (1 << 8),  /* internal file data is allocated */
 	GIT_DIFF_FLAG__UNMAP_DATA = (1 << 9),  /* internal file data is mmap'ed */
 	GIT_DIFF_FLAG__NO_DATA    = (1 << 10), /* file data should not be loaded */
-	GIT_DIFF_FLAG__TO_DELETE  = (1 << 11), /* delete entry during rename det. */
-	GIT_DIFF_FLAG__TO_SPLIT   = (1 << 12), /* split entry during rename det. */
+
+	GIT_DIFF_FLAG__TO_DELETE  = (1 << 16), /* delete entry during rename det. */
+	GIT_DIFF_FLAG__TO_SPLIT   = (1 << 17), /* split entry during rename det. */
+	GIT_DIFF_FLAG__IS_RENAME_TARGET = (1 << 18),
+	GIT_DIFF_FLAG__IS_RENAME_SOURCE = (1 << 19),
+	GIT_DIFF_FLAG__HAS_SELF_SIMILARITY = (1 << 20),
 };
 
+#define GIT_DIFF_FLAG__CLEAR_INTERNAL(F) (F) = ((F) & 0x00FFFF)
+
+#define GIT_DIFF__VERBOSE  (1 << 30)
+
 struct git_diff_list {
 	git_refcount     rc;
 	git_repository   *repo;

src/diff_output.c

@@ -236,9 +236,8 @@ static int get_blob_content(
 		char oidstr[GIT_OID_HEXSZ+1];
 		git_buf content = GIT_BUF_INIT;
 
-		git_oid_fmt(oidstr, &file->oid);
-		oidstr[GIT_OID_HEXSZ] = 0;
-		git_buf_printf(&content, "Subproject commit %s\n", oidstr );
+		git_oid_tostr(oidstr, sizeof(oidstr), &file->oid);
+		git_buf_printf(&content, "Subproject commit %s\n", oidstr);
 
 		map->data = git_buf_detach(&content);
 		map->len = strlen(map->data);
@@ -318,14 +317,13 @@ static int get_workdir_sm_content(
 		}
 	}
 
-	git_oid_fmt(oidstr, &file->oid);
-	oidstr[GIT_OID_HEXSZ] = '\0';
+	git_oid_tostr(oidstr, sizeof(oidstr), &file->oid);
 
 	if (GIT_SUBMODULE_STATUS_IS_WD_DIRTY(sm_status))
 		sm_status_text = "-dirty";
 
-	git_buf_printf(&content, "Subproject commit %s%s\n",
-				   oidstr, sm_status_text);
+	git_buf_printf(
+		&content, "Subproject commit %s%s\n", oidstr, sm_status_text);
 
 	map->data = git_buf_detach(&content);
 	map->len = strlen(map->data);
@@ -1021,8 +1019,33 @@ typedef struct {
 	git_diff_data_cb print_cb;
 	void *payload;
 	git_buf *buf;
+	int oid_strlen;
 } diff_print_info;
 
+static int diff_print_info_init(
+	diff_print_info *pi,
+	git_buf *out, git_diff_list *diff, git_diff_data_cb cb, void *payload)
+{
+	assert(diff && diff->repo);
+
+	pi->diff     = diff;
+	pi->print_cb = cb;
+	pi->payload  = payload;
+	pi->buf      = out;
+
+	if (git_repository__cvar(&pi->oid_strlen, diff->repo, GIT_CVAR_ABBREV) < 0)
+		return -1;
+
+	pi->oid_strlen += 1; /* for NUL byte */
+
+	if (pi->oid_strlen < 2)
+		pi->oid_strlen = 2;
+	else if (pi->oid_strlen > GIT_OID_HEXSZ + 1)
+		pi->oid_strlen = GIT_OID_HEXSZ + 1;
+
+	return 0;
+}
+
 static char pick_suffix(int mode)
 {
 	if (S_ISDIR(mode))
@@ -1106,34 +1129,79 @@ int git_diff_print_compact(
 	git_buf buf = GIT_BUF_INIT;
 	diff_print_info pi;
 
-	pi.diff     = diff;
-	pi.print_cb = print_cb;
-	pi.payload  = payload;
-	pi.buf      = &buf;
-
-	error = git_diff_foreach(diff, print_compact, NULL, NULL, &pi);
+	if (!(error = diff_print_info_init(&pi, &buf, diff, print_cb, payload)))
+		error = git_diff_foreach(diff, print_compact, NULL, NULL, &pi);
 
 	git_buf_free(&buf);
 
 	return error;
 }
 
-static int print_oid_range(diff_print_info *pi, const git_diff_delta *delta)
+static int print_raw(
+	const git_diff_delta *delta, float progress, void *data)
 {
-	int abbrevlen;
+	diff_print_info *pi = data;
+	char code = git_diff_status_char(delta->status);
 	char start_oid[GIT_OID_HEXSZ+1], end_oid[GIT_OID_HEXSZ+1];
 
-	if (git_repository__cvar(&abbrevlen, pi->diff->repo, GIT_CVAR_ABBREV) < 0)
+	GIT_UNUSED(progress);
+
+	if (code == ' ')
+		return 0;
+
+	git_buf_clear(pi->buf);
+
+	git_oid_tostr(start_oid, pi->oid_strlen, &delta->old_file.oid);
+	git_oid_tostr(end_oid, pi->oid_strlen, &delta->new_file.oid);
+
+	git_buf_printf(
+		pi->buf, ":%06o %06o %s... %s... %c",
+		delta->old_file.mode, delta->new_file.mode, start_oid, end_oid, code);
+
+	if (delta->similarity > 0)
+		git_buf_printf(pi->buf, "%03u", delta->similarity);
+
+	if (delta->status == GIT_DELTA_RENAMED || delta->status == GIT_DELTA_COPIED)
+		git_buf_printf(
+			pi->buf, "\t%s %s\n", delta->old_file.path, delta->new_file.path);
+	else
+		git_buf_printf(
+			pi->buf, "\t%s\n", delta->old_file.path ?
+			delta->old_file.path : delta->new_file.path);
+
+	if (git_buf_oom(pi->buf))
 		return -1;
 
-	abbrevlen += 1; /* for NUL byte */
-	if (abbrevlen < 2)
-		abbrevlen = 2;
-	else if (abbrevlen > (int)sizeof(start_oid))
-		abbrevlen = (int)sizeof(start_oid);
+	if (pi->print_cb(delta, NULL, GIT_DIFF_LINE_FILE_HDR,
+			git_buf_cstr(pi->buf), git_buf_len(pi->buf), pi->payload))
+		return callback_error();
+
+	return 0;
+}
 
-	git_oid_tostr(start_oid, abbrevlen, &delta->old_file.oid);
-	git_oid_tostr(end_oid, abbrevlen, &delta->new_file.oid);
+int git_diff_print_raw(
+	git_diff_list *diff,
+	git_diff_data_cb print_cb,
+	void *payload)
+{
+	int error;
+	git_buf buf = GIT_BUF_INIT;
+	diff_print_info pi;
+
+	if (!(error = diff_print_info_init(&pi, &buf, diff, print_cb, payload)))
+		error = git_diff_foreach(diff, print_raw, NULL, NULL, &pi);
+
+	git_buf_free(&buf);
+
+	return error;
+}
+
+static int print_oid_range(diff_print_info *pi, const git_diff_delta *delta)
+{
+	char start_oid[GIT_OID_HEXSZ+1], end_oid[GIT_OID_HEXSZ+1];
+
+	git_oid_tostr(start_oid, pi->oid_strlen, &delta->old_file.oid);
+	git_oid_tostr(end_oid, pi->oid_strlen, &delta->new_file.oid);
 
 	/* TODO: Match git diff more closely */
 	if (delta->old_file.mode == delta->new_file.mode) {
@@ -1289,13 +1357,9 @@ int git_diff_print_patch(
 	git_buf buf = GIT_BUF_INIT;
 	diff_print_info pi;
 
-	pi.diff     = diff;
-	pi.print_cb = print_cb;
-	pi.payload  = payload;
-	pi.buf      = &buf;
-
-	error = git_diff_foreach(
-		diff, print_patch_file, print_patch_hunk, print_patch_line, &pi);
+	if (!(error = diff_print_info_init(&pi, &buf, diff, print_cb, payload)))
+		error = git_diff_foreach(
+			diff, print_patch_file, print_patch_hunk, print_patch_line, &pi);
 
 	git_buf_free(&buf);
 
@@ -1736,12 +1800,9 @@ int git_diff_patch_print(
 
 	assert(patch && print_cb);
 
-	pi.diff     = patch->diff;
-	pi.print_cb = print_cb;
-	pi.payload  = payload;
-	pi.buf      = &temp;
-
-	error = print_patch_file(patch->delta, 0, &pi);
+	if (!(error = diff_print_info_init(
+			&pi, &temp, patch->diff, print_cb, payload)))
+		error = print_patch_file(patch->delta, 0, &pi);
 
 	for (h = 0; h < patch->hunks_size && !error; ++h) {
 		diff_patch_hunk *hunk = &patch->hunks[h];

src/fileops.c

@@ -202,6 +202,32 @@ int git_futils_readbuffer(git_buf *buf, const char *path)
 	return git_futils_readbuffer_updated(buf, path, NULL, NULL, NULL);
 }
 
+int git_futils_writebuffer(
+	const git_buf *buf,	const char *path, int flags, mode_t mode)
+{
+	int fd, error = 0;
+
+	if (flags <= 0)
+		flags = O_CREAT | O_TRUNC | O_WRONLY;
+	if (!mode)
+		mode = GIT_FILEMODE_BLOB;
+
+	if ((fd = p_open(path, flags, mode)) < 0) {
+		giterr_set(GITERR_OS, "Could not open '%s' for writing", path);
+		return fd;
+	}
+
+	if ((error = p_write(fd, git_buf_cstr(buf), git_buf_len(buf))) < 0) {
+		giterr_set(GITERR_OS, "Could not write to '%s'", path);
+		(void)p_close(fd);
+	}
+
+	if ((error = p_close(fd)) < 0)
+		giterr_set(GITERR_OS, "Error while closing '%s'", path);
+
+	return error;
+}
+
 int git_futils_mv_withpath(const char *from, const char *to, const mode_t dirmode)
 {
 	if (git_futils_mkpath2file(to, dirmode) < 0)

src/fileops.h

@@ -22,6 +22,9 @@ extern int git_futils_readbuffer_updated(
 	git_buf *obj, const char *path, time_t *mtime, size_t *size, int *updated);
 extern int git_futils_readbuffer_fd(git_buf *obj, git_file fd, size_t len);
 
+extern int git_futils_writebuffer(
+	const git_buf *buf, const char *path, int open_flags, mode_t mode);
+
 /**
  * File utils
  *
@@ -223,6 +226,7 @@ extern git_off_t git_futils_filesize(git_file fd);
 #define GIT_MODE_PERMS_MASK			0777
 #define GIT_CANONICAL_PERMS(MODE)	(((MODE) & 0100) ? 0755 : 0644)
 #define GIT_MODE_TYPE(MODE)			((MODE) & ~GIT_MODE_PERMS_MASK)
+#define GIT_MODE_ISBLOB(MODE)		(GIT_MODE_TYPE(MODE) == GIT_MODE_TYPE(GIT_FILEMODE_BLOB))
 
 /**
  * Convert a mode_t from the OS to a legal git mode_t value.

src/oid.c

@@ -68,12 +68,31 @@ GIT_INLINE(char) *fmt_one(char *str, unsigned int val)
 	return str;
 }
 
-void git_oid_fmt(char *str, const git_oid *oid)
+void git_oid_nfmt(char *str, size_t n, const git_oid *oid)
 {
-	size_t i;
+	size_t i, max_i;
+
+	if (!oid) {
+		memset(str, 0, n);
+		return;
+	}
+	if (n > GIT_OID_HEXSZ) {
+		memset(&str[GIT_OID_HEXSZ], 0, n - GIT_OID_HEXSZ);
+		n = GIT_OID_HEXSZ;
+	}
+
+	max_i = n / 2;
 
-	for (i = 0; i < sizeof(oid->id); i++)
+	for (i = 0; i < max_i; i++)
 		str = fmt_one(str, oid->id[i]);
+
+	if (n & 1)
+		*str++ = to_hex[oid->id[i] >> 4];
+}
+
+void git_oid_fmt(char *str, const git_oid *oid)
+{
+	git_oid_nfmt(str, GIT_OID_HEXSZ, oid);
 }
 
 void git_oid_pathfmt(char *str, const git_oid *oid)
@@ -91,31 +110,20 @@ char *git_oid_allocfmt(const git_oid *oid)
 	char *str = git__malloc(GIT_OID_HEXSZ + 1);
 	if (!str)
 		return NULL;
-	git_oid_fmt(str, oid);
-	str[GIT_OID_HEXSZ] = '\0';
+	git_oid_nfmt(str, GIT_OID_HEXSZ + 1, oid);
 	return str;
 }
 
 char *git_oid_tostr(char *out, size_t n, const git_oid *oid)
 {
-	char str[GIT_OID_HEXSZ];
-
 	if (!out || n == 0)
 		return "";
 
-	n--; /* allow room for terminating NUL */
-
-	if (oid == NULL)
-		n = 0;
-
-	if (n > 0) {
-		git_oid_fmt(str, oid);
-		if (n > GIT_OID_HEXSZ)
-			n = GIT_OID_HEXSZ;
-		memcpy(out, str, n);
-	}
+	if (n > GIT_OID_HEXSZ + 1)
+		n = GIT_OID_HEXSZ + 1;
 
-	out[n] = '\0';
+	git_oid_nfmt(out, n - 1, oid); /* allow room for terminating NUL */
+	out[n - 1] = '\0';
 
 	return out;
 }

src/util.h

@@ -109,6 +109,13 @@ GIT_INLINE(int) git__is_sizet(git_off_t p)
 	return p == (git_off_t)r;
 }
 
+/** @return true if p fits into the range of a uint32_t */
+GIT_INLINE(int) git__is_uint32(size_t p)
+{
+	uint32_t r = (uint32_t)p;
+	return p == (size_t)r;
+}
+
 /* 32-bit cross-platform rotl */
 #ifdef _MSC_VER /* use built-in method in MSVC */
 #	define git__rotl(v, s) (uint32_t)_rotl(v, s)

tests-clar/diff/diff_helpers.c

@@ -213,3 +213,8 @@ void diff_print(FILE *fp, git_diff_list *diff)
 {
 	cl_git_pass(git_diff_print_patch(diff, diff_print_cb, fp ? fp : stderr));
 }
+
+void diff_print_raw(FILE *fp, git_diff_list *diff)
+{
+	cl_git_pass(git_diff_print_raw(diff, diff_print_cb, fp ? fp : stderr));
+}

tests-clar/diff/diff_helpers.h

@@ -65,4 +65,4 @@ extern int diff_foreach_via_iterator(
 	void *data);
 
 extern void diff_print(FILE *fp, git_diff_list *diff);
-
+extern void diff_print_raw(FILE *fp, git_diff_list *diff);

tests-clar/object/raw/convert.c

@@ -73,3 +73,40 @@ void test_object_raw_convert__succeed_on_oid_to_string_conversion_big(void)
 	cl_assert(str && str == big && *(str+GIT_OID_HEXSZ+2) == 'Y');
 	cl_assert(str && str == big && *(str+GIT_OID_HEXSZ+3) == 'Z');
 }
+
+static void check_partial_oid(
+	char *buffer, size_t count, const git_oid *oid, const char *expected)
+{
+	git_oid_nfmt(buffer, count, oid);
+	buffer[count] = '\0';
+	cl_assert_equal_s(expected, buffer);
+}
+
+void test_object_raw_convert__convert_oid_partially(void)
+{
+	const char *exp = "16a0123456789abcdef4b775213c23a8bd74f5e0";
+	git_oid in;
+	char big[GIT_OID_HEXSZ + 1 + 3]; /* note + 4 => big buffer */
+
+	cl_git_pass(git_oid_fromstr(&in, exp));
+
+	git_oid_nfmt(big, sizeof(big), &in);
+	cl_assert_equal_s(exp, big);
+
+	git_oid_nfmt(big, GIT_OID_HEXSZ + 1, &in);
+	cl_assert_equal_s(exp, big);
+
+	check_partial_oid(big, 1, &in, "1");
+	check_partial_oid(big, 2, &in, "16");
+	check_partial_oid(big, 3, &in, "16a");
+	check_partial_oid(big, 4, &in, "16a0");
+	check_partial_oid(big, 5, &in, "16a01");
+
+	check_partial_oid(big, GIT_OID_HEXSZ, &in, exp);
+	check_partial_oid(
+		big, GIT_OID_HEXSZ - 1, &in, "16a0123456789abcdef4b775213c23a8bd74f5e");
+	check_partial_oid(
+		big, GIT_OID_HEXSZ - 2, &in, "16a0123456789abcdef4b775213c23a8bd74f5");
+	check_partial_oid(
+		big, GIT_OID_HEXSZ - 3, &in, "16a0123456789abcdef4b775213c23a8bd74f");
+}