object-file: move safe_create_leading_directories() into "path.c"

The `safe_create_leading_directories()` function and its relatives are
located in "object-file.c", which is not a good fit as they provide
generic functionality not related to objects at all. Move them into
"path.c", which already hosts `safe_create_dir()` and its relative
`safe_create_dir_in_gitdir()`.

"path.c" is free of `the_repository`, but the moved functions depend on
`the_repository` to read the "core.sharedRepository" config. Adapt the
function signature to accept a repository as argument to fix the issue
and adjust callers accordingly.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

path.c

@@ -931,6 +931,86 @@ int safe_create_dir_in_gitdir(struct repository *repo, const char *path)
 	return adjust_shared_perm(repo, path);
 }
 
+static enum scld_error safe_create_leading_directories_1(struct repository *repo,
+							 char *path)
+{
+	char *next_component = path + offset_1st_component(path);
+	enum scld_error ret = SCLD_OK;
+
+	while (ret == SCLD_OK && next_component) {
+		struct stat st;
+		char *slash = next_component, slash_character;
+
+		while (*slash && !is_dir_sep(*slash))
+			slash++;
+
+		if (!*slash)
+			break;
+
+		next_component = slash + 1;
+		while (is_dir_sep(*next_component))
+			next_component++;
+		if (!*next_component)
+			break;
+
+		slash_character = *slash;
+		*slash = '\0';
+		if (!stat(path, &st)) {
+			/* path exists */
+			if (!S_ISDIR(st.st_mode)) {
+				errno = ENOTDIR;
+				ret = SCLD_EXISTS;
+			}
+		} else if (mkdir(path, 0777)) {
+			if (errno == EEXIST &&
+			    !stat(path, &st) && S_ISDIR(st.st_mode))
+				; /* somebody created it since we checked */
+			else if (errno == ENOENT)
+				/*
+				 * Either mkdir() failed because
+				 * somebody just pruned the containing
+				 * directory, or stat() failed because
+				 * the file that was in our way was
+				 * just removed.  Either way, inform
+				 * the caller that it might be worth
+				 * trying again:
+				 */
+				ret = SCLD_VANISHED;
+			else
+				ret = SCLD_FAILED;
+		} else if (repo && adjust_shared_perm(repo, path)) {
+			ret = SCLD_PERMS;
+		}
+		*slash = slash_character;
+	}
+	return ret;
+}
+
+enum scld_error safe_create_leading_directories(struct repository *repo,
+						char *path)
+{
+	return safe_create_leading_directories_1(repo, path);
+}
+
+enum scld_error safe_create_leading_directories_no_share(char *path)
+{
+	return safe_create_leading_directories_1(NULL, path);
+}
+
+enum scld_error safe_create_leading_directories_const(struct repository *repo,
+						      const char *path)
+{
+	int save_errno;
+	/* path points to cache entries, so xstrdup before messing with it */
+	char *buf = xstrdup(path);
+	enum scld_error result = safe_create_leading_directories(repo, buf);
+
+	save_errno = errno;
+	free(buf);
+	errno = save_errno;
+	return result;
+}
+
 static int have_same_root(const char *path1, const char *path2)
 {
 	int is_abs1, is_abs2;