[PATCH] git-log: detect dup and fdopen failure

From

Jim Meyering <jim@meyering.net>

Date

Jun 27, 2007, 13:02 UTC

Message-ID

<87r6nxo8iq.fsf_-_@rho.meyering.net>

In-Reply-To

<81b0412b0706270548p6f694fd6x5f47cbefa16c08ac@mail.gmail.com>

"Alex Riesen" <raa.lkml@gmail.com> wrote:

> On 6/27/07, Jim Meyering <jim@meyering.net> wrote:
>> Without this, if you ever run out of file descriptors, dup will
>> fail (silently), fdopen will return NULL, and fprintf will
>> try to dereference NULL (i.e., usually segfault).
>
> But if you check the result of fdopen for NULL instead
> you'll cover the dup failure _and_ out-of-memory in one
> go. You'll loose the errno (probably), but you don't seem
> to use it here anyway.

Here's a better patch:

Signed-off-by: Jim Meyering <jim@meyering.net>
---
 builtin-log.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/builtin-log.c b/builtin-log.c
index 073a2a1..7b0d6f4 100644
--- a/builtin-log.c
+++ b/builtin-log.c
@@ -588,8 +588,12 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	if (ignore_if_in_upstream)
 		get_patch_ids(&rev, &ids, prefix);

-	if (!use_stdout)
-		realstdout = fdopen(dup(1), "w");
+	if (!use_stdout) {
+		int fd = dup(1);
+		if (fd < 0 || (realstdout = fdopen(fd, "w")) == NULL)
+			die("failed to duplicate standard output: %s",
+			    strerror(errno));
+	}

 	prepare_revision_walk(&rev);
 	while ((commit = get_revision(&rev)) != NULL) {