[PATCH] server-info: avoid calling fclose(3) twice in update_info_file()

From: René Scharfe <l.s.r@web.de>
Date: Apr 16, 2017, 16:55 UTC
Message-ID: <137d732f-7a23-8a8a-9f2b-7f16bb361c5a@web.de>

If an error occurs when or after closing the stream we call fclose(3) again in the error handler. The second call can exhibit undefined behavior, so make sure to call fclose(3) at most once. Also avoid calling close(2) after fd has been successfully associated with the stream, as fclose(3) has become responsible for doing that beyond this point.

Found with Cppcheck.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
---
 server-info.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/server-info.c b/server-info.c
index 7bc4e75d22..f6c1a3dfb0 100644
--- a/server-info.c
+++ b/server-info.c
@@ -14,19 +14,21 @@ static int update_info_file(char *path, int (*generate)(FILE *))
 	char *tmp = mkpathdup("%s_XXXXXX", path);
 	int ret = -1;
 	int fd = -1;
-	FILE *fp = NULL;
+	FILE *fp = NULL, *to_close;
 
 	safe_create_leading_directories(path);
 	fd = git_mkstemp_mode(tmp, 0666);
 	if (fd < 0)
 		goto out;
-	fp = fdopen(fd, "w");
+	to_close = fp = fdopen(fd, "w");
 	if (!fp)
 		goto out;
+	fd = -1;
 	ret = generate(fp);
 	if (ret)
 		goto out;
-	if (fclose(fp))
+	fp = NULL;
+	if (fclose(to_close))
 		goto out;
 	if (adjust_shared_perm(tmp) < 0)
 		goto out;

-- 
2.12.2