Temporarily restore old (itimer) sleep variant because new one

(nanosleep) breaks Apache httpd badly: his childs died quickly after
number of requests (SIGPIPE). To reproduce this bug start
gdb /usr/local/sbin/httpd
run -X

and make some bunch of concurent requests (load the server pages
from 3 different places f.e.)
After short time httpd dies via SIGPIPE. It never dies with old sleep.c

In real life it looks like lots of broken images on the pages or missing
pages. Lynx says about Network read error, etc.
It seems something wrong in nanosleep signal handling.

1 files changed, 70 insertions, 9 deletions

diff --git a/lib/libc/gen/sleep.c b/lib/libc/gen/sleep.c
index 87aeb36..b3dd8b7 100644
--- a/lib/libc/gen/sleep.c
+++ b/lib/libc/gen/sleep.c
@@ -38,19 +38,80 @@ static char sccsid[] = "@(#)sleep.c	8.1 (Berkeley) 6/4/93";
 #include <sys/time.h>
 #include <signal.h>
 #include <unistd.h>
+#ifdef  _THREAD_SAFE
+#include <pthread.h>
+#include "pthread_private.h"
+#else
+
+#define	setvec(vec, a) \
+	vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0
+
+static int ringring;
+#endif
 
 unsigned int
 sleep(seconds)
 	unsigned int seconds;
 {
-	struct timespec time_to_sleep;
-	struct timespec time_remaining;
-
-	if (seconds != 0) {
-		time_to_sleep.tv_sec = seconds;
-		time_to_sleep.tv_nsec = 0;
-		nanosleep(&time_to_sleep, &time_remaining);
-		seconds = time_remaining.tv_sec;
+#ifdef  _THREAD_SAFE
+    struct timespec time_to_sleep;
+    struct timespec time_remaining;
+
+    if (seconds) {
+        time_to_sleep.tv_sec = seconds;
+        time_to_sleep.tv_nsec = 0;
+        nanosleep(&time_to_sleep,&time_remaining);
+        seconds = time_remaining.tv_sec;
+    }
+    return(seconds);
+#else
+	register struct itimerval *itp;
+	struct itimerval itv, oitv;
+	struct sigvec vec, ovec;
+	long omask;
+	static void sleephandler();
+
+	itp = &itv;
+	if (!seconds)
+		return 0;
+	timerclear(&itp->it_interval);
+	timerclear(&itp->it_value);
+	if (setitimer(ITIMER_REAL, itp, &oitv) < 0)
+		return seconds;
+	itp->it_value.tv_sec = seconds;
+	if (timerisset(&oitv.it_value)) {
+		if (timercmp(&oitv.it_value, &itp->it_value, >))
+			oitv.it_value.tv_sec -= itp->it_value.tv_sec;
+		else {
+			itp->it_value = oitv.it_value;
+			/*
+			 * This is a hack, but we must have time to return
+			 * from the setitimer after the alarm or else it'll
+			 * be restarted.  And, anyway, sleep never did
+			 * anything more than this before.
+			 */
+			oitv.it_value.tv_sec = 1;
+			oitv.it_value.tv_usec = 0;
+		}
 	}
-	return (seconds);
+	setvec(vec, sleephandler);
+	(void) sigvec(SIGALRM, &vec, &ovec);
+	omask = sigblock(sigmask(SIGALRM));
+	ringring = 0;
+	(void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0);
+	while (!ringring)
+		sigpause(omask &~ sigmask(SIGALRM));
+	(void) sigvec(SIGALRM, &ovec, (struct sigvec *)0);
+	(void) sigsetmask(omask);
+	(void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0);
+	return 0;
+#endif
+}
+
+#ifndef  _THREAD_SAFE
+static void
+sleephandler()
+{
+	ringring = 1;
 }
+#endif