[PATCH v3 2/4] object-file: refactor map_loose_object_1()

[Jonathan Tan <jonathantanmy@xxxxxxxxxx>]

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

Split this function up. Only one caller needs 1, so inline that. As for
2, a future patch will also need this functionality and, in addition,
the calculated path, so extract this into a separate function with an
out parameter for the path.

Signed-off-by: Jonathan Tan <jonathantanmy@xxxxxxxxxx>
---
 object-file.c | 60 +++++++++++++++++++++++++++++----------------------
 1 file changed, 34 insertions(+), 26 deletions(-)

diff --git a/object-file.c b/object-file.c
index cf724bc19b..d99d05839f 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1211,43 +1211,48 @@ static int quick_has_loose(struct repository *r,
 }
 
 /*
- * Map the loose object at "path" if it is not NULL, or the path found by
- * searching for a loose object named "oid".
+ * Map and close the given loose object fd. The path argument is used for
+ * error reporting.
  */
-static void *map_loose_object_1(struct repository *r, const char *path,
-			     const struct object_id *oid, unsigned long *size)
+static void *map_fd(int fd, const char *path, unsigned long *size)
 {
-	void *map;
-	int fd;
-
-	if (path)
-		fd = git_open(path);
-	else
-		fd = open_loose_object(r, oid, &path);
-	map = NULL;
-	if (fd >= 0) {
-		struct stat st;
+	void *map = NULL;
+	struct stat st;
 
-		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);
+	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;
 		}
-		close(fd);
+		map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
 	}
+	close(fd);
 	return map;
 }
 
+static void *map_loose_object_1(struct repository *r,
+				const struct object_id *oid,
+				unsigned long *size,
+				const char **path)
+{
+	const char *p;
+	int fd = open_loose_object(r, oid, &p);
+
+	if (fd < 0)
+		return NULL;
+	if (path)
+		*path = p;
+	return map_fd(fd, p, size);
+}
+
 void *map_loose_object(struct repository *r,
 		       const struct object_id *oid,
 		       unsigned long *size)
 {
-	return map_loose_object_1(r, NULL, oid, size);
+	return map_loose_object_1(r, oid, size, NULL);
 }
 
 enum unpack_loose_header_result unpack_loose_header(git_zstream *stream,
@@ -2789,13 +2794,16 @@ 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;
-- 
2.39.0.rc1.256.g54fd8350bd-goog