object-file: refactor map_loose_object_1()

This function can do 3 things:
 1. Gets an fd given a path
 2. Simultaneously gets a path and fd given an OID
 3. Memory maps an fd

Keep 3 (renaming the function accordingly) and inline 1 and 2 into their
respective callers.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

object-file.c

@@ -1211,35 +1211,25 @@ static int quick_has_loose(struct repository *r,
 }
 
 /*
- * Map the loose object at "path" if it is not NULL, or the path found by
+ * Map and close the given loose object fd. The path argument is used for
- * searching for a loose object named "oid".
+ * error reporting.
  */
-static void *map_loose_object_1(struct repository *r, const char *path,
+static void *map_fd(int fd, const char *path, unsigned long *size)
-			     const struct object_id *oid, unsigned long *size)
 {
-	void *map;
+	void *map = NULL;
-	int fd;
+	struct stat st;
 
-	if (path)
+	if (!fstat(fd, &st)) {
-		fd = git_open(path);
+		*size = xsize_t(st.st_size);
-	else
+		if (!*size) {
-		fd = open_loose_object(r, oid, &path);
+			/* mmap() is forbidden on empty files */
-	map = NULL;
+			error(_("object file %s is empty"), path);
-	if (fd >= 0) {
+			close(fd);
-		struct stat st;
+			return NULL;
-
-		if (!fstat(fd, &st)) {
-			*size = xsize_t(st.st_size);
-			if (!*size) {
-				/* mmap() is forbidden on empty files */
-				error(_("object file %s is empty"), path);
-				close(fd);
-				return NULL;
-			}
-			map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
 		}
-		close(fd);
+		map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
 	}
+	close(fd);
 	return map;
 }
 
@@ -1247,7 +1237,12 @@ void *map_loose_object(struct repository *r,
 		       const struct object_id *oid,
 		       unsigned long *size)
 {
-	return map_loose_object_1(r, NULL, oid, size);
+	const char *p;
+	int fd = open_loose_object(r, oid, &p);
+
+	if (fd < 0)
+		return NULL;
+	return map_fd(fd, p, size);
 }
 
 enum unpack_loose_header_result unpack_loose_header(git_zstream *stream,
@@ -2789,13 +2784,16 @@ int read_loose_object(const char *path,
 		      struct object_info *oi)
 {
 	int ret = -1;
+	int fd;
 	void *map = NULL;
 	unsigned long mapsize;
 	git_zstream stream;
 	char hdr[MAX_HEADER_LEN];
 	unsigned long *size = oi->sizep;
 
-	map = map_loose_object_1(the_repository, path, NULL, &mapsize);
+	fd = git_open(path);
+	if (fd >= 0)
+		map = map_fd(fd, path, &mapsize);
 	if (!map) {
 		error_errno(_("unable to mmap %s"), path);
 		goto out;