glibc/support/xsysconf.c
Stafford Horne 2efca218b5 xsysconf: Only fail on error results and errno set
When testing nptl/tst-pthread-attr-affinity-fail fails with:

    error: xsysconf.c:33: sysconf (83): Cannot allocate memory
    error: 1 test failures

This happens as xsysconf checks the errno after running sysconf.
Internally the sysconf request for _SC_NPROCESSORS_CONF on linux
allocates memory.  But there is a problem, even though malloc succeeds
errno is getting set to ENOMEM.

POSIX allows successful calls to clobber errno.  So xsysconf just
checking errno is wrong.  Fix xsysconf by only failing if we have an
error result and errno is set.
2021-09-24 17:30:03 +09:00

37 lines
1.2 KiB
C

/* Error-checking wrapper for sysconf.
Copyright (C) 2017-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <support/check.h>
#include <support/xunistd.h>
long
xsysconf (int name)
{
/* Detect errors by a changed errno value, in case -1 is a valid
value. Make sure that the caller does not see the zero value for
errno. */
int old_errno = errno;
errno = 0;
long result = sysconf (name);
if (result == -1 && errno != 0)
FAIL_EXIT1 ("sysconf (%d): %m", name);
errno = old_errno;
return result;
}