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From: "Dan Langille" <dan@langille.org>
To: hackers@freebsd.org
Date: Tue, 16 Sep 2003 20:23:41 -0400
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Subject: [PATCH] : libc_r/uthread/uthread_write.c
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I've had preliminary success with this patch.  More testing needs 
to be done, but in the meantime, I would appreciate reviews and 
comments.  The patched code is available from
http://beta.freebsddiary.org/tmp/uthread_write.c and the patch
appears below.

In short, the logic has been changed to ensure that if __sys_write
returns zero, this value is returned by _write.

The syslog calls are just for debugging and will be removed.

Thank you.

--- uthread_write.c.org	Tue Sep 16 12:14:22 2003
+++ uthread_write.c	Tue Sep 16 16:38:02 2003
@@ -39,6 +39,7 @@
 #include <unistd.h>
 #include <pthread.h>
 #include "pthread_private.h"
+#include <syslog.h>
 
 ssize_t
 _write(int fd, const void *buf, size_t nbytes)
@@ -93,7 +94,7 @@
 			 * write:
 			 */
 			if (blocking && ((n < 0 && (errno == EWOULDBLOCK ||
-			    errno == EAGAIN)) || (n >= 0 && num < nbytes))) {
+			    errno == EAGAIN)) || (n > 0 && num < nbytes))) {
 				curthread->data.fd.fd = fd;
 				_thread_kern_set_timeout(NULL);
 
@@ -136,6 +137,15 @@
 					ret = num;
 				else
 					ret = n;
+
+			} else if (n == 0) {
+				ret = 0;
+				if (n == 0) {
+					setlogmask (LOG_UPTO (LOG_NOTICE));
+					openlog("uthread_write.c", LOG_CONS | LOG_PID | LOG_NDELAY, 
LOG_LOCAL1);
+					syslog (LOG_NOTICE, "zero has been returned in uthread_write.c; 
num = '%d'", num); 
+				}
+				break;
 
 			/* Check if the write has completed: */
 			} else if (num >= nbytes)

-- 
Dan Langille : http://www.langille.org/