/* Implementation of the POSIX sleep function using nanosleep. Copyright (C) 1996, 1997, 1998, 1999 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2 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 Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with the GNU C Library; see the file COPYING.LIB. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include <errno.h> #include <time.h> #include <signal.h> #include <unistd.h> /* version perusing nanosleep */ #if defined __UCLIBC_HAS_REALTIME__ #if 0 /* This is a quick and dirty, but not 100% compliant with * the stupid SysV SIGCHLD vs. SIG_IGN behaviour. It is * fine unless you are messing with SIGCHLD... */ unsigned int sleep (unsigned int sec) { unsigned int res; struct timespec ts = { .tv_sec = (long int) seconds, .tv_nsec = 0 }; res = nanosleep(&ts, &ts); if (res) res = (unsigned int) ts.tv_sec + (ts.tv_nsec >= 500000000L); return res; } #else /* We are going to use the `nanosleep' syscall of the kernel. But the kernel does not implement the sstupid SysV SIGCHLD vs. SIG_IGN behaviour for this syscall. Therefore we have to emulate it here. */ unsigned int sleep (unsigned int seconds) { struct timespec ts = { .tv_sec = (long int) seconds, .tv_nsec = 0 }; sigset_t set, oset; unsigned int result; /* This is not necessary but some buggy programs depend on this. */ if (seconds == 0) return 0; /* Linux will wake up the system call, nanosleep, when SIGCHLD arrives even if SIGCHLD is ignored. We have to deal with it in libc. We block SIGCHLD first. */ __sigemptyset (&set); __sigaddset (&set, SIGCHLD); sigprocmask (SIG_BLOCK, &set, &oset); /* can't fail */ /* If SIGCHLD is already blocked, we don't have to do anything. */ if (!__sigismember (&oset, SIGCHLD)) { int saved_errno; struct sigaction oact; __sigemptyset (&set); __sigaddset (&set, SIGCHLD); sigaction (SIGCHLD, NULL, &oact); /* never fails */ if (oact.sa_handler == SIG_IGN) { /* We should leave SIGCHLD blocked. */ result = nanosleep (&ts, &ts); saved_errno = errno; /* Restore the original signal mask. */ sigprocmask (SIG_SETMASK, &oset, NULL); __set_errno (saved_errno); } else { /* We should unblock SIGCHLD. Restore the original signal mask. */ sigprocmask (SIG_SETMASK, &oset, NULL); result = nanosleep (&ts, &ts); } } else result = nanosleep (&ts, &ts); if (result != 0) /* Round remaining time. */ result = (unsigned int) ts.tv_sec + (ts.tv_nsec >= 500000000L); return result; } #endif #else /* __UCLIBC_HAS_REALTIME__ */ /* no nanosleep, use signals and alarm() */ static void sleep_alarm_handler(int attribute_unused sig) { } unsigned int sleep (unsigned int seconds) { struct sigaction act, oact; sigset_t set, oset; unsigned int result, remaining; time_t before, after; int old_errno = errno; /* This is not necessary but some buggy programs depend on this. */ if (seconds == 0) return 0; /* block SIGALRM */ __sigemptyset (&set); __sigaddset (&set, SIGALRM); sigprocmask (SIG_BLOCK, &set, &oset); /* can't fail */ act.sa_handler = sleep_alarm_handler; act.sa_flags = 0; act.sa_mask = oset; sigaction(SIGALRM, &act, &oact); /* never fails */ before = time(NULL); remaining = alarm(seconds); if (remaining && remaining > seconds) { /* restore user's alarm */ sigaction(SIGALRM, &oact, NULL); alarm(remaining); /* restore old alarm */ sigsuspend(&oset); after = time(NULL); } else { sigsuspend (&oset); after = time(NULL); sigaction (SIGALRM, &oact, NULL); } result = after - before; alarm(remaining > result ? remaining - result : 0); sigprocmask (SIG_SETMASK, &oset, NULL); __set_errno(old_errno); return result > seconds ? 0 : seconds - result; } #endif /* __UCLIBC_HAS_REALTIME__ */ libc_hidden_def(sleep)