--- fflush.c.bsdnew 2009-11-11 13:33:04.000000000 -0800
+++ fflush.c 2009-11-11 13:33:04.000000000 -0800
@@ -39,6 +39,7 @@ __FBSDID("$FreeBSD: src/lib/libc/stdio/f
#include "namespace.h"
#include <errno.h>
#include <stdio.h>
+#include <string.h>
#include "un-namespace.h"
#include "libc_private.h"
#include "local.h"
@@ -122,6 +123,14 @@ __sflush(FILE *fp)
for (; n > 0; n -= t, p += t) {
t = _swrite(fp, (char *)p, n);
if (t <= 0) {
+ /* 5340694: reset _p and _w on EAGAIN */
+ if (t < 0 && errno == EAGAIN) {
+ if (p > fp->_p) /* some was written */
+ memmove(fp->_p, p, n);
+ fp->_p += n;
+ if (!(fp->_flags & (__SLBF|__SNBF)))
+ fp->_w -= n;
+ }
fp->_flags |= __SERR;
return (EOF);
}