glibc/support/xsysconf.c
Florian Weimer 446d22e91d Linux: Implement interfaces for memory protection keys
This adds system call wrappers for pkey_alloc, pkey_free, pkey_mprotect,
and x86-64 implementations of pkey_get and pkey_set, which abstract over
the PKRU CPU register and hide the actual number of memory protection
keys supported by the CPU.  pkey_mprotect with a -1 key is implemented
using mprotect, so it will work even if the kernel does not support the
pkey_mprotect system call.

The system call wrapers use unsigned int instead of unsigned long for
parameters, so that no special treatment for x32 is needed.  The flags
argument is currently unused, and the access rights bit mask is limited
to two bits by the current PKRU register layout anyway.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
2017-12-05 15:20:35 +01:00

37 lines
1.2 KiB
C

/* Error-checking wrapper for sysconf.
Copyright (C) 2017 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
<http://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 (errno != 0)
FAIL_EXIT1 ("sysconf (%d): %m", name);
errno = old_errno;
return result;
}