initial import

sysdeps/posix/sleep.c

@@ -0,0 +1,106 @@
+/* Copyright (C) 1991, 1992, 1993 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
+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., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <ansidecl.h>
+#include <signal.h>
+#include <time.h>
+#include <unistd.h>
+#include <errno.h>
+
+
+/* SIGALRM signal handler for `sleep'.  This does nothing but return,
+   but SIG_IGN isn't supposed to break `pause'.  */
+static void
+DEFUN(sleep_handler, (sig), 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).
+   If a signal handler does a `longjmp' or modifies the handling of the
+   SIGALRM signal while inside `sleep' call, the handling of the SIGALRM
+   signal afterwards is undefined.  There is no return value to indicate
+   error, but if `sleep' returns SECONDS, it probably didn't work.  */
+unsigned int
+DEFUN(sleep, (seconds), 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;
+  if (sigemptyset (&act.sa_mask) < 0 ||
+      sigaction (SIGALRM, &act, &oact) < 0)
+    return seconds;
+
+  before = time ((time_t *) NULL);
+  remaining = alarm (seconds);
+
+  if (remaining > 0 && remaining < seconds)
+    {
+      /* 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);
+    }
+  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);
+
+      /* Restore the old signal action state.  */
+      (void) sigaction (SIGALRM, &oact, (struct sigaction *) NULL);
+    }
+
+  /* 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.  */
+  errno = save;
+
+  return slept > seconds ? 0 : seconds - slept;
+}