From patchwork Wed Apr  7 21:02:34 2010
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Subject: [6/8] char: unix: For files that are nonblocking,
 report -EAGAIN to calling functions
Date: Wed, 07 Apr 2010 11:02:34 -0000
From: Amit Shah <amit.shah@redhat.com>
X-Patchwork-Id: 49647
Message-Id: <1270674156-9345-7-git-send-email-amit.shah@redhat.com>
To: qemu list <qemu-devel@nongnu.org>
Cc: Amit Shah <amit.shah@redhat.com>, Paul Brook <paul@codesourcery.com>,
 "Michael S. Tsirkin" <mst@redhat.com>,
 Gerd Hoffmann <kraxel@redhat.com>, Juan Quintela <quintela@redhat.com>

If the chardev we're writing to is nonblocking, just report -EAGAIN to
the caller so that the caller can take any further action if it so
wishes.

Signed-off-by: Amit Shah <amit.shah@redhat.com>

---
qemu-char.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index 208466f..57e9af3 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -497,11 +497,23 @@ int send_all(int fd, const void *buf, int len1)
 static int unix_write(int fd, const uint8_t *buf, int len1)
 {
     int ret, len;
+    int flags;
+    bool nonblock;
+
+    flags = fcntl(fd, F_GETFL);
+    if (flags == -1) {
+        flags = 0;
+    }
+
+    nonblock = flags & O_NONBLOCK;
 
     len = len1;
     while (len > 0) {
         ret = write(fd, buf, len);
         if (ret < 0) {
+            if (errno == EAGAIN && nonblock) {
+                return -EAGAIN;
+            }
             if (errno != EINTR && errno != EAGAIN) {
                 if (len1 - len) {
                     return len1 - len;