Bug 507868

Summary:	futimesat doesn't handle AT_FDCWD
Product:	[Developer tools] valgrind	Reporter:	Mark Wielaard <mark>
Component:	general	Assignee:	mcermak
Status:	RESOLVED FIXED
Severity:	normal
Priority:	NOR
Version First Reported In:	3.25 GIT
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Bug Depends on:
Bug Blocks:	506971
Attachments:	proposed patch proposed patch proposed patch

Description Mark Wielaard 2025-08-04 21:48:21 UTC

Like other "at" syscalls fd can have the special value AT_FDCWD which is an "invalid file descriptor".

The LTP futimesat01 testcase shows:

==695142== Warning: invalid file descriptor -100 in syscall futimesat()
futimesat01    5  TFAIL  :  futimesat01.c:85: futimesat() failed: TEST_ERRNO=EBADF(9): Bad file descriptor

There is no LTP testcase for it, but if pathname is absolute, then fd is ignored.

Comment 1 mcermak 2025-08-05 12:58:08 UTC

Created attachment 183803 [details]
proposed patch

Comment 2 mcermak 2025-08-05 13:33:08 UTC

Created attachment 183805 [details]
proposed patch

Comment 3 mcermak 2025-08-05 14:56:04 UTC

Created attachment 183808 [details]
proposed patch

Comment 4 Mark Wielaard 2025-08-06 17:24:08 UTC

(In reply to mcermak from comment #3)
> Created attachment 183808 [details]
> proposed patch

Looks good. Pushed as:

commit bdbce5686e4204d678814fa861d153c5bc5252f8
Author: Martin Cermak <mcermak@redhat.com>
Date:   Tue Aug 5 16:54:54 2025 +0200

    The futimesat syscall wrapper doesn't handle AT_FDCWD
    
    Update futimesat syscall wrapper so that it doesn't consider the
    special value AT_FDCWD (-100) an invalid file descriptor.
    
    https://bugs.kde.org/show_bug.cgi?id=507868