nanosleep(3), and sleep(3) rewrite, by Erik van der Kouwe

include/time.h

@@ -72,4 +72,14 @@ _PROTOTYPE( int stime, (time_t *_top)					);
 
 extern long timezone;
 
+#ifdef _POSIX_SOURCE
+struct timespec
+{
+	time_t tv_sec;
+	long tv_nsec;
+};
+
+int nanosleep(const struct timespec *rqtp, struct timespec *rmtp);
+#endif
+
 #endif /* _TIME_H */

lib/posix/Makefile.in

@@ -56,6 +56,7 @@ libc_FILES=" \
 	_mkfifo.c \
 	_mknod.c \
 	_mmap.c \
+	_nanosleep.c \
 	_open.c \
 	_opendir.c \
 	_pathconf.c \

lib/posix/_nanosleep.c

@@ -0,0 +1,77 @@
+/* nanosleep() - Sleep for a number of nanoseconds. Author: Erik van der Kouwe
+ *								  25 July 2009
+ */
+
+#include <lib.h>
+#define nanosleep _nanosleep
+#include <unistd.h>
+#include <errno.h>
+#include <time.h>
+#include <sys/select.h>
+#include <sys/time.h>
+
+#define MSEC_PER_SEC 1000
+#define USEC_PER_MSEC 1000
+#define NSEC_PER_USEC 1000
+
+#define USEC_PER_SEC (USEC_PER_MSEC * MSEC_PER_SEC)
+#define NSEC_PER_SEC (NSEC_PER_USEC * USEC_PER_SEC)
+
+int nanosleep(const struct timespec *rqtp, struct timespec *rmtp)
+{
+	struct timeval timeout, timestart = { 0, 0 }, timeend;
+	int errno_select, r;
+
+	/* keep track of start time if needed */
+	if (rmtp)
+	{
+		rmtp->tv_sec = 0;
+		rmtp->tv_nsec = 0;
+		if (gettimeofday(&timestart, NULL) < 0)
+			return -1;
+	}
+
+	/* use select to wait */
+	timeout.tv_sec = rqtp->tv_sec;
+	timeout.tv_usec = (rqtp->tv_nsec + NSEC_PER_USEC - 1) / NSEC_PER_USEC;
+	r = select(0, NULL, NULL, NULL, &timeout);
+
+	/* return remaining time only if requested */
+	/* if select succeeded then we slept all time */
+	if (!rmtp || r >= 0)
+		return r;
+
+	/* measure end time; preserve errno */
+	errno_select = errno;
+	if (gettimeofday(&timeend, NULL) < 0)
+		return -1;
+
+	errno = errno_select;
+
+	/* compute remaining time */
+	rmtp->tv_sec = rqtp->tv_sec - (timeend.tv_sec - timestart.tv_sec);
+	rmtp->tv_nsec = rqtp->tv_nsec -
+		(timeend.tv_usec - timestart.tv_usec) * NSEC_PER_USEC;
+
+	/* bring remaining time into canonical form */
+	while (rmtp->tv_nsec < 0)
+	{
+		rmtp->tv_sec -= 1;
+		rmtp->tv_nsec += NSEC_PER_SEC;
+	}
+
+	while (rmtp->tv_nsec > NSEC_PER_SEC)
+	{
+		rmtp->tv_sec += 1;
+		rmtp->tv_nsec -= NSEC_PER_SEC;
+	}
+
+	/* remaining time must not be negative */
+	if (rmtp->tv_sec < 0)
+	{
+		rmtp->tv_sec = 0;
+		rmtp->tv_nsec = 0;
+	}
+
+	return r;
+}

lib/posix/_sleep.c

@@ -1,69 +1,22 @@
-/*	sleep() - Sleep for a number of seconds.	Author: Kees J. Bot
+/*	sleep() - Sleep for a number of seconds.  Author: Erik van der Kouwe
- *								24 Apr 2000
+ *								25 July 2009
- * (Inspired by the Minix-vmd version of same, except that
- * this implementation doesn't bother to check if all the signal
- * functions succeed.  Under Minix that is no problem.)
  */
 
 #include <lib.h>
 #define sleep _sleep
-#include <signal.h>
-#include <unistd.h>
 #include <time.h>
 
-static void handler(int sig)
-{
-	/* Dummy signal handler. */
-}
-
 unsigned sleep(unsigned sleep_seconds)
 {
-	sigset_t ss_full, ss_orig, ss_alarm;
+	struct timespec rqtp, rmtp;
-	struct sigaction action_alarm, action_orig;
-	unsigned alarm_seconds, nap_seconds;
 
-	if (sleep_seconds == 0) return 0;	/* No rest for the wicked */
+	/* nanosleep implements this call;
+	 * ignore failure, it cannot be reported
+	 */
+	rqtp.tv_sec = sleep_seconds;
+	rqtp.tv_nsec = 0;
+	nanosleep(&rqtp, &rmtp);
 
-	/* Mask all signals. */
+	/* round remainder up to seconds */
-	sigfillset(&ss_full);
+	return rmtp.tv_sec + ((rmtp.tv_nsec > 0) ? 1 : 0);
-	sigprocmask(SIG_BLOCK, &ss_full, &ss_orig);
-
-	/* Cancel currently running alarm. */
-	alarm_seconds= alarm(0);
-
-	/* How long can we nap without interruptions? */
-	nap_seconds= sleep_seconds;
-	if (alarm_seconds != 0 && alarm_seconds < sleep_seconds) {
-		nap_seconds= alarm_seconds;
-	}
-
-	/* Now sleep. */
-	action_alarm.sa_handler= handler;
-	sigemptyset(&action_alarm.sa_mask);
-	action_alarm.sa_flags= 0;
-	sigaction(SIGALRM, &action_alarm, &action_orig);
-	alarm(nap_seconds);
-
-	/* Wait for a wakeup call, either our alarm, or some other signal. */
-	ss_alarm= ss_orig;
-	sigdelset(&ss_alarm, SIGALRM);
-	sigsuspend(&ss_alarm);
-
-	/* Cancel alarm, set mask and stuff back to normal. */
-	nap_seconds -= alarm(0);
-	sigaction(SIGALRM, &action_orig, NULL);
-	sigprocmask(SIG_SETMASK, &ss_orig, NULL);
-
-	/* Restore alarm counter to the time remaining. */
-	if (alarm_seconds != 0 && alarm_seconds >= nap_seconds) {
-		alarm_seconds -= nap_seconds;
-		if (alarm_seconds == 0) {
-			raise(SIGALRM);		/* Alarm expires now! */
-		} else {
-			alarm(alarm_seconds);	/* Count time remaining. */
-		}
-	}
-
-	/* Return time not slept. */
-	return sleep_seconds - nap_seconds;
 }

lib/syscall/Makefile.in

@@ -70,6 +70,7 @@ libc_FILES=" \
 	mknod.s \
 	mmap.s \
 	mount.s \
+	nanosleep.s \
 	open.s \
 	opendir.s \
 	pathconf.s \

lib/syscall/nanosleep.s

@@ -0,0 +1,6 @@
+.sect .text
+.extern	__nanosleep
+.define	_nanosleep
+
+_nanosleep:
+	jmp	__nanosleep