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authorRoland McGrath <roland@hack.frob.com>2012-09-28 16:22:51 -0700
committerRoland McGrath <roland@hack.frob.com>2012-09-28 16:26:33 -0700
commitea4d37b3169908615b7c17c9c506c6a6c16b3a26 (patch)
treede8978356ea5977e2f56cccaf1a562f7bc02fdd2 /sysdeps
parent1fa1170b529e5a3a0c81b1e3bfb99ddfba423069 (diff)
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Implement POSIX-generic sleep via nanosleep rather than SIGARLM.
Diffstat (limited to 'sysdeps')
-rw-r--r--sysdeps/posix/sleep.c100
1 files changed, 35 insertions, 65 deletions
diff --git a/sysdeps/posix/sleep.c b/sysdeps/posix/sleep.c
index dfd7420..b3c9e27 100644
--- a/sysdeps/posix/sleep.c
+++ b/sysdeps/posix/sleep.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 1991, 1992, 1993, 1996, 1997 Free Software Foundation, Inc.
+/* Sleep for a given number of seconds. POSIX.1 version.
+ Copyright (C) 1991-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -15,20 +16,12 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
-#include <signal.h>
#include <time.h>
#include <unistd.h>
#include <errno.h>
+#include <sys/param.h>
-/* SIGALRM signal handler for `sleep'. This does nothing but return,
- but SIG_IGN isn't supposed to break `pause'. */
-static void
-sleep_handler (int sig)
-{
- return;
-}
-
/* Make the process sleep for SECONDS seconds, or until a signal arrives
and is not ignored. The function returns the number of seconds less
than SECONDS which it actually slept (zero if it slept the full time).
@@ -39,67 +32,44 @@ sleep_handler (int sig)
unsigned int
__sleep (unsigned int seconds)
{
- unsigned int remaining, slept;
- time_t before, after;
- sigset_t set, oset;
- struct sigaction act, oact;
- int save = errno;
-
- if (seconds == 0)
- return 0;
-
- /* Block SIGALRM signals while frobbing the handler. */
- if (sigemptyset (&set) < 0 ||
- sigaddset (&set, SIGALRM) < 0 ||
- sigprocmask (SIG_BLOCK, &set, &oset))
- return seconds;
-
- act.sa_handler = sleep_handler;
- act.sa_flags = 0;
- act.sa_mask = oset; /* execute handler with original mask */
- if (sigaction (SIGALRM, &act, &oact) < 0)
- return seconds;
-
- before = time ((time_t *) NULL);
- remaining = alarm (seconds);
-
- if (remaining > 0 && remaining < seconds)
+ /* This is not necessary but some buggy programs depend on it. */
+ if (__builtin_expect (seconds == 0, 0))
{
- /* The user's alarm will expire before our own would.
- Restore the user's signal action state and let his alarm happen. */
- (void) sigaction (SIGALRM, &oact, (struct sigaction *) NULL);
- alarm (remaining); /* Restore sooner alarm. */
- sigsuspend (&oset); /* Wait for it to go off. */
- after = time ((time_t *) NULL);
+#ifdef CANCELLATION_P
+ CANCELLATION_P (THREAD_SELF);
+#endif
+ return 0;
}
- else
- {
- /* Atomically restore the old signal mask
- (which had better not block SIGALRM),
- and wait for a signal to arrive. */
- sigsuspend (&oset);
- after = time ((time_t *) NULL);
+ int save_errno = errno;
- /* Restore the old signal action state. */
- (void) sigaction (SIGALRM, &oact, (struct sigaction *) NULL);
+ const unsigned int max
+ = (unsigned int) (((unsigned long int) (~((time_t) 0))) >> 1);
+ struct timespec ts = { 0, 0 };
+ do
+ {
+ if (sizeof (ts.tv_sec) <= sizeof (seconds))
+ {
+ /* Since SECONDS is unsigned assigning the value to .tv_sec can
+ overflow it. In this case we have to wait in steps. */
+ ts.tv_sec += MIN (seconds, max);
+ seconds -= (unsigned int) ts.tv_sec;
+ }
+ else
+ {
+ ts.tv_sec = (time_t) seconds;
+ seconds = 0;
+ }
+
+ if (__nanosleep (&ts, &ts) < 0)
+ /* We were interrupted.
+ Return the number of (whole) seconds we have not yet slept. */
+ return seconds + ts.tv_sec;
}
+ while (seconds > 0);
- /* Notice how long we actually slept. */
- slept = after - before;
-
- /* Restore the user's alarm if we have not already past it.
- If we have, be sure to turn off the alarm in case a signal
- other than SIGALRM was what woke us up. */
- (void) alarm (remaining > slept ? remaining - slept : 0);
-
- /* Restore the original signal mask. */
- (void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
-
- /* Restore the `errno' value we started with.
- Some of the calls we made might have failed, but we didn't care. */
- __set_errno (save);
+ __set_errno (save_errno);
- return slept > seconds ? 0 : seconds - slept;
+ return 0;
}
weak_alias (__sleep, sleep)