From 5572db65ce5a2d0d159ec3ba20d47934303915cb Mon Sep 17 00:00:00 2001
From: Eric Andersen <andersen@codepoet.org>
Date: Wed, 2 Jan 2002 12:10:01 +0000
Subject: Fix usleep to work correctly.  Fix sleep behavior in the presence of
 SIGCHLD.  -Erik

---
 libc/unistd/sleep.c | 112 +++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 98 insertions(+), 14 deletions(-)

(limited to 'libc/unistd/sleep.c')

diff --git a/libc/unistd/sleep.c b/libc/unistd/sleep.c
index b6c410fb5..f67d969e3 100644
--- a/libc/unistd/sleep.c
+++ b/libc/unistd/sleep.c
@@ -1,24 +1,108 @@
+/* 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.
 
-#include <sys/time.h>
-#include <sys/types.h>
+   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>
 
-int usleep (__useconds_t usec)
+#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)
 {
-	struct timeval tv;
-
-	tv.tv_sec = usec / 1000000;
-	tv.tv_usec = usec % 1000000;
-	return(select(0, 0, 0, 0, &tv));
+	struct timespec ts = { 
+	    tv_sec:  (long int)(sec / 1000000),
+	    tv_nsec: 0 
+	};
+	nanosleep(&ts, &ts);
+	return(sec-ts.tv_sec);
 }
 
-unsigned int sleep(unsigned int sec)
+#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 timeval tv;
+    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.  */
+    if (__sigemptyset (&set) < 0
+	    || __sigaddset (&set, SIGCHLD) < 0
+	    || sigprocmask (SIG_BLOCK, &set, &oset))
+	return -1;
+
+    /* If SIGCHLD is already blocked, we don't have to do anything.  */
+    if (!__sigismember (&oset, SIGCHLD))
+    {
+	int saved_errno;
+	struct sigaction oact;
+
+	if (__sigemptyset (&set) < 0 || __sigaddset (&set, SIGCHLD) < 0)
+	    return -1;
+
+	/* We get the signal handler for SIGCHLD.  */
+	if (sigaction (SIGCHLD, (struct sigaction *) NULL, &oact) < 0)
+	{
+	    saved_errno = errno;
+	    /* Restore the original signal mask.  */
+	    (void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
+	    __set_errno (saved_errno);
+	    return -1;
+	}
+
+	if (oact.sa_handler == SIG_IGN)
+	{
+	    /* We should leave SIGCHLD blocked.  */
+	    result = nanosleep (&ts, &ts);
+
+	    saved_errno = errno;
+	    /* Restore the original signal mask.  */
+	    (void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
+	    __set_errno (saved_errno);
+	}
+	else
+	{
+	    /* We should unblock SIGCHLD.  Restore the original signal mask.  */
+	    (void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) 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);
 
-	tv.tv_sec = sec;
-	tv.tv_usec = 0;
-	select(0, 0, 0, 0, &tv);
-	return tv.tv_sec;
+    return result;
 }
+#endif
-- 
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