Permalink
Cannot retrieve contributors at this time
Name already in use
A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
glibc/sysdeps/unix/sysv/linux/sysconf.c
Go to fileThis commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
146 lines (122 sloc)
3.82 KB
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
/* Get file-specific information about a file. Linux version. | |
Copyright (C) 2003-2016 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 <fcntl.h> | |
#include <stdlib.h> | |
#include <sysdep.h> | |
#include <time.h> | |
#include <unistd.h> | |
#include <sys/resource.h> | |
#include <sys/param.h> | |
#include <not-cancel.h> | |
#include <ldsodefs.h> | |
/* Legacy value of ARG_MAX. The macro is now not defined since the | |
actual value varies based on the stack size. */ | |
#define legacy_ARG_MAX 131072 | |
static long int posix_sysconf (int name); | |
#ifndef HAS_CPUCLOCK | |
static long int | |
has_cpuclock (int name) | |
{ | |
# if defined __NR_clock_getres || HP_TIMING_AVAIL | |
/* If we have HP_TIMING, we will fall back on that if the system | |
call does not work, so we support it either way. */ | |
# if !HP_TIMING_AVAIL | |
/* Check using the clock_getres system call. */ | |
struct timespec ts; | |
INTERNAL_SYSCALL_DECL (err); | |
int r = INTERNAL_SYSCALL (clock_getres, err, 2, | |
(name == _SC_CPUTIME | |
? CLOCK_PROCESS_CPUTIME_ID | |
: CLOCK_THREAD_CPUTIME_ID), | |
&ts); | |
if (INTERNAL_SYSCALL_ERROR_P (r, err)) | |
return -1; | |
# endif | |
return _POSIX_VERSION; | |
# else | |
return -1; | |
# endif | |
} | |
# define HAS_CPUCLOCK(name) has_cpuclock (name) | |
#endif | |
/* Get the value of the system variable NAME. */ | |
long int | |
__sysconf (int name) | |
{ | |
const char *procfname = NULL; | |
switch (name) | |
{ | |
struct rlimit rlimit; | |
#ifdef __NR_clock_getres | |
case _SC_MONOTONIC_CLOCK: | |
/* Check using the clock_getres system call. */ | |
{ | |
struct timespec ts; | |
INTERNAL_SYSCALL_DECL (err); | |
int r; | |
r = INTERNAL_SYSCALL (clock_getres, err, 2, CLOCK_MONOTONIC, &ts); | |
return INTERNAL_SYSCALL_ERROR_P (r, err) ? -1 : _POSIX_VERSION; | |
} | |
#endif | |
case _SC_CPUTIME: | |
case _SC_THREAD_CPUTIME: | |
return HAS_CPUCLOCK (name); | |
case _SC_ARG_MAX: | |
/* Use getrlimit to get the stack limit. */ | |
if (__getrlimit (RLIMIT_STACK, &rlimit) == 0) | |
return MAX (legacy_ARG_MAX, rlimit.rlim_cur / 4); | |
return legacy_ARG_MAX; | |
case _SC_NGROUPS_MAX: | |
/* Try to read the information from the /proc/sys/kernel/ngroups_max | |
file. */ | |
procfname = "/proc/sys/kernel/ngroups_max"; | |
break; | |
case _SC_SIGQUEUE_MAX: | |
if (__getrlimit (RLIMIT_SIGPENDING, &rlimit) == 0) | |
return rlimit.rlim_cur; | |
/* The /proc/sys/kernel/rtsig-max file contains the answer. */ | |
procfname = "/proc/sys/kernel/rtsig-max"; | |
break; | |
default: | |
break; | |
} | |
if (procfname != NULL) | |
{ | |
int fd = open_not_cancel_2 (procfname, O_RDONLY); | |
if (fd != -1) | |
{ | |
/* This is more than enough, the file contains a single integer. */ | |
char buf[32]; | |
ssize_t n; | |
n = TEMP_FAILURE_RETRY (read_not_cancel (fd, buf, sizeof (buf) - 1)); | |
close_not_cancel_no_status (fd); | |
if (n > 0) | |
{ | |
/* Terminate the string. */ | |
buf[n] = '\0'; | |
char *endp; | |
long int res = strtol (buf, &endp, 10); | |
if (endp != buf && (*endp == '\0' || *endp == '\n')) | |
return res; | |
} | |
} | |
} | |
return posix_sysconf (name); | |
} | |
/* Now the POSIX version. */ | |
#undef __sysconf | |
#define __sysconf static posix_sysconf | |
#include <sysdeps/posix/sysconf.c> |