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153 lines
4.1 KiB
C
153 lines
4.1 KiB
C
/* Get file-specific information about a file. Linux version.
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Copyright (C) 2003,2004,2006 2008,2009,2011 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <errno.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <sysdep.h>
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#include <time.h>
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#include <unistd.h>
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#include <sys/resource.h>
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#include <not-cancel.h>
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#include <ldsodefs.h>
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/* Legacy value of ARG_MAX. The macro is now not defined since the
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actual value varies based on the stack size. */
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#define legacy_ARG_MAX 131072
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static long int posix_sysconf (int name);
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#ifndef HAS_CPUCLOCK
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static long int
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has_cpuclock (void)
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{
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# if defined __NR_clock_getres || HP_TIMING_AVAIL
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/* If we have HP_TIMING, we will fall back on that if the system
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call does not work, so we support it either way. */
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# if !HP_TIMING_AVAIL
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/* Check using the clock_getres system call. */
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struct timespec ts;
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INTERNAL_SYSCALL_DECL (err);
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int r = INTERNAL_SYSCALL (clock_getres, err, 2,
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(name == _SC_CPUTIME
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? CLOCK_PROCESS_CPUTIME_ID
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: CLOCK_THREAD_CPUTIME_ID),
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&ts);
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if (INTERNAL_SYSCALL_ERROR_P (r, err))
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return -1;
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# endif
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return _POSIX_VERSION;
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# else
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return -1;
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# endif
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}
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# define HAS_CPUCLOCK() has_cpuclock ()
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#endif
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/* Get the value of the system variable NAME. */
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long int
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__sysconf (int name)
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{
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const char *procfname = NULL;
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switch (name)
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{
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struct rlimit rlimit;
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#ifdef __NR_clock_getres
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case _SC_MONOTONIC_CLOCK:
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/* Check using the clock_getres system call. */
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{
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struct timespec ts;
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INTERNAL_SYSCALL_DECL (err);
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int r;
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r = INTERNAL_SYSCALL (clock_getres, err, 2, CLOCK_MONOTONIC, &ts);
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return INTERNAL_SYSCALL_ERROR_P (r, err) ? -1 : _POSIX_VERSION;
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}
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#endif
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case _SC_CPUTIME:
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case _SC_THREAD_CPUTIME:
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return HAS_CPUCLOCK ();
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case _SC_ARG_MAX:
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#if __LINUX_KERNEL_VERSION < 0x020617
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/* Determine whether this is a kernel 2.6.23 or later. Only
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then do we have an argument limit determined by the stack
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size. */
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if (GLRO(dl_discover_osversion) () >= 0x020617)
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#endif
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/* Use getrlimit to get the stack limit. */
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if (__getrlimit (RLIMIT_STACK, &rlimit) == 0)
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return MAX (legacy_ARG_MAX, rlimit.rlim_cur / 4);
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return legacy_ARG_MAX;
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case _SC_NGROUPS_MAX:
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/* Try to read the information from the /proc/sys/kernel/ngroups_max
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file. */
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procfname = "/proc/sys/kernel/ngroups_max";
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break;
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case _SC_SIGQUEUE_MAX:
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if (__getrlimit (RLIMIT_SIGPENDING, &rlimit) == 0)
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return rlimit.rlim_cur;
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/* The /proc/sys/kernel/rtsig-max file contains the answer. */
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procfname = "/proc/sys/kernel/rtsig-max";
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break;
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default:
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break;
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}
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if (procfname != NULL)
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{
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int fd = open_not_cancel_2 (procfname, O_RDONLY);
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if (fd != -1)
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{
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/* This is more than enough, the file contains a single integer. */
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char buf[32];
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ssize_t n;
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n = TEMP_FAILURE_RETRY (read_not_cancel (fd, buf, sizeof (buf) - 1));
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close_not_cancel_no_status (fd);
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if (n > 0)
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{
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/* Terminate the string. */
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buf[n] = '\0';
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char *endp;
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long int res = strtol (buf, &endp, 10);
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if (endp != buf && (*endp == '\0' || *endp == '\n'))
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return res;
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}
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}
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}
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return posix_sysconf (name);
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}
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/* Now the POSIX version. */
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#undef __sysconf
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#define __sysconf static posix_sysconf
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#include <sysdeps/posix/sysconf.c>
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