/* Get file-specific information about a file. Linux version. Copyright (C) 2003-2017 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 . */ #include #include #include #include #include #include #include #include #include #include /* 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_nocancel (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