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git.ipfire.org Git - thirdparty/glibc.git/blob - sysdeps/unix/sysv/linux/sysconf.c
1 /* Get file-specific information about a file. Linux version.
2 Copyright (C) 2003-2015 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, see
17 <http://www.gnu.org/licenses/>. */
25 #include <sys/resource.h>
26 #include <sys/param.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
);
40 has_cpuclock (int name
)
42 # if defined __NR_clock_getres || HP_TIMING_AVAIL
43 /* If we have HP_TIMING, we will fall back on that if the system
44 call does not work, so we support it either way. */
46 /* Check using the clock_getres system call. */
48 INTERNAL_SYSCALL_DECL (err
);
49 int r
= INTERNAL_SYSCALL (clock_getres
, err
, 2,
51 ? CLOCK_PROCESS_CPUTIME_ID
52 : CLOCK_THREAD_CPUTIME_ID
),
54 if (INTERNAL_SYSCALL_ERROR_P (r
, err
))
57 return _POSIX_VERSION
;
62 # define HAS_CPUCLOCK(name) has_cpuclock (name)
66 /* Get the value of the system variable NAME. */
70 const char *procfname
= NULL
;
75 #ifdef __NR_clock_getres
76 case _SC_MONOTONIC_CLOCK
:
77 /* Check using the clock_getres system call. */
80 INTERNAL_SYSCALL_DECL (err
);
82 r
= INTERNAL_SYSCALL (clock_getres
, err
, 2, CLOCK_MONOTONIC
, &ts
);
83 return INTERNAL_SYSCALL_ERROR_P (r
, err
) ? -1 : _POSIX_VERSION
;
88 case _SC_THREAD_CPUTIME
:
89 return HAS_CPUCLOCK (name
);
92 /* Use getrlimit to get the stack limit. */
93 if (__getrlimit (RLIMIT_STACK
, &rlimit
) == 0)
94 return MAX (legacy_ARG_MAX
, rlimit
.rlim_cur
/ 4);
96 return legacy_ARG_MAX
;
99 /* Try to read the information from the /proc/sys/kernel/ngroups_max
101 procfname
= "/proc/sys/kernel/ngroups_max";
104 case _SC_SIGQUEUE_MAX
:
105 if (__getrlimit (RLIMIT_SIGPENDING
, &rlimit
) == 0)
106 return rlimit
.rlim_cur
;
108 /* The /proc/sys/kernel/rtsig-max file contains the answer. */
109 procfname
= "/proc/sys/kernel/rtsig-max";
116 if (procfname
!= NULL
)
118 int fd
= open_not_cancel_2 (procfname
, O_RDONLY
);
121 /* This is more than enough, the file contains a single integer. */
124 n
= TEMP_FAILURE_RETRY (read_not_cancel (fd
, buf
, sizeof (buf
) - 1));
125 close_not_cancel_no_status (fd
);
129 /* Terminate the string. */
133 long int res
= strtol (buf
, &endp
, 10);
134 if (endp
!= buf
&& (*endp
== '\0' || *endp
== '\n'))
140 return posix_sysconf (name
);
143 /* Now the POSIX version. */
145 #define __sysconf static posix_sysconf
146 #include <sysdeps/posix/sysconf.c>