Filebuf: Fixed a TODO in filebuf (real lock in lock_file)

Added gitfo_creat_locked and gitfo_creat_locked_force

src/filebuf.c

@@ -41,16 +41,14 @@ static int lock_file(git_filebuf *file, int flags)
 
 	/* create path to the file buffer is required */
 	if (flags & GIT_FILEBUF_FORCE) {
-		file->fd = gitfo_creat_force(file->path_lock, 0644);
+		file->fd = gitfo_creat_locked_force(file->path_lock, 0644);
 	} else {
-		file->fd = gitfo_creat(file->path_lock, 0644);
+		file->fd = gitfo_creat_locked(file->path_lock, 0644);
 	}
 
 	if (file->fd < 0)
 		return git__throw(GIT_EOSERR, "Failed to create lock");
 
-	/* TODO: do a flock() in the descriptor file_lock */
-
 	if ((flags & GIT_FILEBUF_APPEND) && gitfo_exists(file->path_original) == 0) {
 		git_file source;
 		char buffer[2048];

src/fileops.c

@@ -66,6 +66,20 @@ int gitfo_creat_force(const char *path, int mode)
 	return gitfo_creat(path, mode);
 }
 
+int gitfo_creat_locked(const char *path, int mode)
+{
+	int fd = open(path, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_EXCL, mode);
+	return fd >= 0 ? fd : git__throw(GIT_EOSERR, "Failed to create locked file. Could not open %s", path);
+}
+
+int gitfo_creat_locked_force(const char *path, int mode)
+{
+	if (gitfo_mkdir_2file(path) < GIT_SUCCESS)
+		return git__throw(GIT_EOSERR, "Failed to create locked file %s", path);
+
+	return gitfo_creat_locked(path, mode);
+}
+
 int gitfo_read(git_file fd, void *buf, size_t cnt)
 {
 	char *b = buf;

src/fileops.h

@@ -65,6 +65,8 @@ extern int gitfo_exists(const char *path);
 extern int gitfo_open(const char *path, int flags);
 extern int gitfo_creat(const char *path, int mode);
 extern int gitfo_creat_force(const char *path, int mode);
+extern int gitfo_creat_locked(const char *path, int mode);
+extern int gitfo_creat_locked_force(const char *path, int mode);
 extern int gitfo_mktemp(char *path_out, const char *filename);
 extern int gitfo_isdir(const char *path);
 extern int gitfo_isfile(const char *path);