[PATCH] sha1_file: use access(), not lstat(), if possible

[Jonathan Tan <jonathantanmy@google.com>]

In sha1_loose_object_info(), use access() (indirectly invoked through
has_loose_object()) instead of lstat() if we do not need the on-disk
size, as it should be faster on Windows [1].

[1] https://public-inbox.org/git/alpine.DEB.2.21.1.1707191450570.4193@virtualbox/

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
---
Thanks for the information - here's a patch. Do you, by any chance, know
of a web page (or similar thing) that I can cite for this?
---
 sha1_file.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/sha1_file.c b/sha1_file.c
index fca165f13..81962b019 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -2920,20 +2920,19 @@ static int sha1_loose_object_info(const unsigned char *sha1,
 
 	/*
 	 * If we don't care about type or size, then we don't
-	 * need to look inside the object at all. Note that we
-	 * do not optimize out the stat call, even if the
-	 * caller doesn't care about the disk-size, since our
-	 * return value implicitly indicates whether the
-	 * object even exists.
+	 * need to look inside the object at all. We only check
+	 * for its existence.
 	 */
 	if (!oi->typep && !oi->typename && !oi->sizep && !oi->contentp) {
-		const char *path;
-		struct stat st;
-		if (stat_sha1_file(sha1, &st, &path) < 0)
-			return -1;
-		if (oi->disk_sizep)
+		if (oi->disk_sizep) {
+			const char *path;
+			struct stat st;
+			if (stat_sha1_file(sha1, &st, &path) < 0)
+				return -1;
 			*oi->disk_sizep = st.st_size;
-		return 0;
+			return 0;
+		}
+		return has_loose_object(sha1) ? 0 : -1;
 	}
 
 	map = map_sha1_file(sha1, &mapsize);
-- 
2.14.0.rc0.284.gd933b75aa4-goog