open: check fd_flags value before calling fcntl

From: AZero13 <[email protected]>

Otherwise, fcntl can be called with invalid fd_flags.

---
open: check fd_flags value before calling fcntl

Otherwise, fcntl can be called with invalid fd_flags.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2131%2FAZero13%2Ffixopen-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2131/AZero13/fixopen-v1
Pull-Request: https://github.com/git/git/pull/2131

 compat/open.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index 37ae2b1aeb..b313bcd364 100644
@@ -44,8 +44,8 @@ int git_open_cloexec(const char *name, int flags)
 
 		if (!o_cloexec && 0 <= fd && fd_cloexec) {
 			/* Opened w/o O_CLOEXEC?  try with fcntl(2) to add it */
-			int flags = fcntl(fd, F_GETFD);
-			if (fcntl(fd, F_SETFD, flags | fd_cloexec))
+			int fd_flags = fcntl(fd, F_GETFD);
+			if (fd_flags < 0 || fcntl(fd, F_SETFD, fd_flags | fd_cloexec))
 				fd_cloexec = 0;
 		}
 	}

base-commit: c4a0c8845e2426375ad257b6c221a3a7d92ecfda

gitgitgadget

This somehow feels mischaracterised. The intent of the code is already to check the current flags value using getfd and or-in the cloexec bit to call setfd. What this patch fixes is to handle a failed getfd case correctly.

Subject: git_open_cloexec(): handle failing F_GETFD

Before using F_SETFD to add in fd_cloexec bit, the code uses F_GETFD to see the current set of flags. As it does not pay attention to potential failures, F_SETFD may be called with a set of invalid fcntl bits.

Continue without calling F_SETFD and behave the same way as the case where F_SETFD failed, when the initial F_GETFD failed.

or something like that, perhaps?

The in-body "From: AZer..." line we see above should say "From: Greg..." instead. Set "git config set user.name 'Greg Funni'" in the repository you use to contribute to this project, amend the commit so that it will record "Greg..." instead of "AZer..." as its author, and force push to GGG and tell GGG to send out the email, perhaps?