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ad0e8eb0 | 1 | /* Get file-specific information about a file. Linux version. |
bfff8b1b | 2 | Copyright (C) 2003-2017 Free Software Foundation, Inc. |
ad0e8eb0 UD |
3 | This file is part of the GNU C Library. |
4 | ||
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. | |
9 | ||
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. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
59ba27a6 PE |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ | |
ad0e8eb0 | 18 | |
bf067910 | 19 | #include <errno.h> |
d024596d | 20 | #include <fcntl.h> |
4c771a3b | 21 | #include <stdlib.h> |
ad0e8eb0 UD |
22 | #include <sysdep.h> |
23 | #include <time.h> | |
24 | #include <unistd.h> | |
7c22c7ec | 25 | #include <sys/resource.h> |
ca06321d | 26 | #include <sys/param.h> |
5db7adc4 | 27 | #include <not-cancel.h> |
7c22c7ec | 28 | #include <ldsodefs.h> |
ad0e8eb0 | 29 | |
f96853be UD |
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 | |
33 | ||
34 | ||
ad0e8eb0 UD |
35 | static long int posix_sysconf (int name); |
36 | ||
ad0e8eb0 | 37 | |
3b85df27 UD |
38 | #ifndef HAS_CPUCLOCK |
39 | static long int | |
f50ef8f1 | 40 | has_cpuclock (int name) |
3b85df27 UD |
41 | { |
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. */ | |
45 | # if !HP_TIMING_AVAIL | |
46 | /* Check using the clock_getres system call. */ | |
47 | struct timespec ts; | |
48 | INTERNAL_SYSCALL_DECL (err); | |
49 | int r = INTERNAL_SYSCALL (clock_getres, err, 2, | |
50 | (name == _SC_CPUTIME | |
51 | ? CLOCK_PROCESS_CPUTIME_ID | |
52 | : CLOCK_THREAD_CPUTIME_ID), | |
53 | &ts); | |
54 | if (INTERNAL_SYSCALL_ERROR_P (r, err)) | |
55 | return -1; | |
56 | # endif | |
57 | return _POSIX_VERSION; | |
58 | # else | |
59 | return -1; | |
60 | # endif | |
61 | } | |
f50ef8f1 | 62 | # define HAS_CPUCLOCK(name) has_cpuclock (name) |
3b85df27 UD |
63 | #endif |
64 | ||
65 | ||
ad0e8eb0 UD |
66 | /* Get the value of the system variable NAME. */ |
67 | long int | |
68 | __sysconf (int name) | |
69 | { | |
3bd1aa47 UD |
70 | const char *procfname = NULL; |
71 | ||
ad0e8eb0 UD |
72 | switch (name) |
73 | { | |
5be0a688 | 74 | struct rlimit rlimit; |
ad0e8eb0 UD |
75 | #ifdef __NR_clock_getres |
76 | case _SC_MONOTONIC_CLOCK: | |
77 | /* Check using the clock_getres system call. */ | |
78 | { | |
79 | struct timespec ts; | |
80 | INTERNAL_SYSCALL_DECL (err); | |
d15851ec RM |
81 | int r; |
82 | r = INTERNAL_SYSCALL (clock_getres, err, 2, CLOCK_MONOTONIC, &ts); | |
fbf86dda | 83 | return INTERNAL_SYSCALL_ERROR_P (r, err) ? -1 : _POSIX_VERSION; |
ad0e8eb0 UD |
84 | } |
85 | #endif | |
86 | ||
182ed12e RM |
87 | case _SC_CPUTIME: |
88 | case _SC_THREAD_CPUTIME: | |
f50ef8f1 | 89 | return HAS_CPUCLOCK (name); |
182ed12e | 90 | |
7c22c7ec | 91 | case _SC_ARG_MAX: |
637461d9 JM |
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); | |
7c22c7ec | 95 | |
f96853be | 96 | return legacy_ARG_MAX; |
7c22c7ec | 97 | |
d024596d | 98 | case _SC_NGROUPS_MAX: |
3bd1aa47 UD |
99 | /* Try to read the information from the /proc/sys/kernel/ngroups_max |
100 | file. */ | |
101 | procfname = "/proc/sys/kernel/ngroups_max"; | |
102 | break; | |
103 | ||
104 | case _SC_SIGQUEUE_MAX: | |
5be0a688 UD |
105 | if (__getrlimit (RLIMIT_SIGPENDING, &rlimit) == 0) |
106 | return rlimit.rlim_cur; | |
107 | ||
3bd1aa47 UD |
108 | /* The /proc/sys/kernel/rtsig-max file contains the answer. */ |
109 | procfname = "/proc/sys/kernel/rtsig-max"; | |
d024596d UD |
110 | break; |
111 | ||
ad0e8eb0 | 112 | default: |
d024596d | 113 | break; |
ad0e8eb0 | 114 | } |
3bd1aa47 UD |
115 | |
116 | if (procfname != NULL) | |
117 | { | |
c2284574 | 118 | int fd = __open_nocancel (procfname, O_RDONLY); |
3bd1aa47 UD |
119 | if (fd != -1) |
120 | { | |
121 | /* This is more than enough, the file contains a single integer. */ | |
122 | char buf[32]; | |
123 | ssize_t n; | |
124 | n = TEMP_FAILURE_RETRY (read_not_cancel (fd, buf, sizeof (buf) - 1)); | |
125 | close_not_cancel_no_status (fd); | |
126 | ||
127 | if (n > 0) | |
128 | { | |
129 | /* Terminate the string. */ | |
130 | buf[n] = '\0'; | |
131 | ||
132 | char *endp; | |
133 | long int res = strtol (buf, &endp, 10); | |
134 | if (endp != buf && (*endp == '\0' || *endp == '\n')) | |
135 | return res; | |
136 | } | |
137 | } | |
138 | } | |
139 | ||
d024596d | 140 | return posix_sysconf (name); |
ad0e8eb0 | 141 | } |
bf067910 UD |
142 | |
143 | /* Now the POSIX version. */ | |
144 | #undef __sysconf | |
145 | #define __sysconf static posix_sysconf | |
146 | #include <sysdeps/posix/sysconf.c> |