[Qemu-devel] [PATCH v2] qemu-char: Do not disconnect when there's data for reading

[Zifei Tong]

After commit 812c1057f6175ac9a9829fa2920a2b5783814193 (Handle G_IO_HUP
in tcp_chr_read for tcp chardev), connections are disconnected when in
G_IO_HUP condition.

However, it's possible that there is still data for reading in the channel.
In that case, the remaining data is not handled.

I saw a related bug when running socat in write-only mode, after

  $ echo "quit" | socat -u - UNIX-CONNECT:qemu-monitor

the monitor won't not run the 'quit' command.

Instead of GIOCondition, this patch uses the return value of tcp_chr_recv()
to check the state of connection as suggested by Kirill.

Cc: Kirill Batuzov <address@hidden>
Cc: Nikolay Nikolaev <address@hidden>
Cc: Markus Armbruster <address@hidden>
Cc: Anthony Liguori <address@hidden>
Signed-off-by: Zifei Tong <address@hidden>
---
 qemu-char.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index 2a3cb9f..6cc69fa 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -2692,12 +2692,6 @@ static gboolean tcp_chr_read(GIOChannel *chan, 
GIOCondition cond, void *opaque)
     uint8_t buf[READ_BUF_LEN];
     int len, size;
 
-    if (cond & G_IO_HUP) {
-        /* connection closed */
-        tcp_chr_disconnect(chr);
-        return TRUE;
-    }
-
     if (!s->connected || s->max_size <= 0) {
         return TRUE;
     }
@@ -2705,7 +2699,7 @@ static gboolean tcp_chr_read(GIOChannel *chan, 
GIOCondition cond, void *opaque)
     if (len > s->max_size)
         len = s->max_size;
     size = tcp_chr_recv(chr, (void *)buf, len);
-    if (size == 0) {
+    if (size == 0 || (size < 0 && !(errno == EAGAIN || errno == EINTR))) {
         /* connection closed */
         tcp_chr_disconnect(chr);
     } else if (size > 0) {
-- 
2.1.0