1 /* Get file-specific information about a file. Linux version.
2 Copyright (C) 2003, 2004, 2006, 2008, 2009 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
26 #include <sys/resource.h>
27 #include <not-cancel.h>
30 /* Legacy value of ARG_MAX. The macro is now not defined since the
31 actual value varies based on the stack size. */
32 #define legacy_ARG_MAX 131072
35 static long int posix_sysconf (int name);
38 /* Get the value of the system variable NAME. */
42 const char *procfname = NULL;
47 #ifdef __NR_clock_getres
48 case _SC_MONOTONIC_CLOCK:
49 /* Check using the clock_getres system call. */
52 INTERNAL_SYSCALL_DECL (err);
54 r = INTERNAL_SYSCALL (clock_getres, err, 2, CLOCK_MONOTONIC, &ts);
55 return INTERNAL_SYSCALL_ERROR_P (r, err) ? -1 : _POSIX_VERSION;
59 #if defined __NR_clock_getres || HP_TIMING_AVAIL
61 case _SC_THREAD_CPUTIME:
63 /* If we have HP_TIMING, we will fall back on that if the system
64 call does not work, so we support it either way. */
66 /* Check using the clock_getres system call. */
68 INTERNAL_SYSCALL_DECL (err);
69 int r = INTERNAL_SYSCALL (clock_getres, err, 2,
71 ? CLOCK_PROCESS_CPUTIME_ID
72 : CLOCK_THREAD_CPUTIME_ID),
74 if (INTERNAL_SYSCALL_ERROR_P (r, err))
77 return _POSIX_VERSION;
82 #if __LINUX_KERNEL_VERSION < 0x020617
83 /* Determine whether this is a kernel 2.6.23 or later. Only
84 then do we have an argument limit determined by the stack
86 if (GLRO(dl_discover_osversion) () >= 0x020617)
88 /* Use getrlimit to get the stack limit. */
89 if (__getrlimit (RLIMIT_STACK, &rlimit) == 0)
90 return MAX (legacy_ARG_MAX, rlimit.rlim_cur / 4);
92 return legacy_ARG_MAX;
95 /* Try to read the information from the /proc/sys/kernel/ngroups_max
97 procfname = "/proc/sys/kernel/ngroups_max";
100 case _SC_SIGQUEUE_MAX:
101 if (__getrlimit (RLIMIT_SIGPENDING, &rlimit) == 0)
102 return rlimit.rlim_cur;
104 /* The /proc/sys/kernel/rtsig-max file contains the answer. */
105 procfname = "/proc/sys/kernel/rtsig-max";
112 if (procfname != NULL)
114 int fd = open_not_cancel_2 (procfname, O_RDONLY);
117 /* This is more than enough, the file contains a single integer. */
120 n = TEMP_FAILURE_RETRY (read_not_cancel (fd, buf, sizeof (buf) - 1));
121 close_not_cancel_no_status (fd);
125 /* Terminate the string. */
129 long int res = strtol (buf, &endp, 10);
130 if (endp != buf && (*endp == '\0' || *endp == '\n'))
136 return posix_sysconf (name);
139 /* Now the POSIX version. */
141 #define __sysconf static posix_sysconf
142 #include <sysdeps/posix/sysconf.c>