| /* Get file-specific information about a file. Linux version. |
| Copyright (C) 2003-2014 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 <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: |
| #if !__ASSUME_ARG_MAX_STACK_BASED |
| /* Determine whether this is a kernel with an argument limit |
| determined by the stack size. */ |
| if (GLRO(dl_discover_osversion) () |
| >= __LINUX_ARG_MAX_STACK_BASED_MIN_KERNEL) |
| #endif |
| /* 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> |