[PATCH] mmap error handling

I have reviewed all occurrences of mmap() in git and fixed three types
of errors/defects:

1) The result is not checked.
2) The file descriptor is closed if mmap() succeeds, but not when it
fails.
3) Various casts applied to -1 are used instead of MAP_FAILED, which is
specifically defined to check mmap() return value.

[jc: This is a second round of Pavel's patch.  He fixed up the problem
that close() potentially clobbering the errno from mmap, which
the first round had.]

Signed-off-by: Pavel Roskin <proski@gnu.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 2 insertions, 4 deletions

diff --git a/rev-cache.c b/rev-cache.c
index ea65274ed..f908ce7a3 100644
--- a/rev-cache.c
+++ b/rev-cache.c
@@ -212,11 +212,9 @@ int read_rev_cache(const char *path, FILE *dumpfile, int dry_run)
 		return -1;
 	}
 	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
-	if (map == MAP_FAILED) {
-		close(fd);
-		return -1;
-	}
 	close(fd);
+	if (map == MAP_FAILED)
+		return -1;
 
 	memset(last_sha1, 0, 20);
 	ofs = 0;