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Re: [Qemu-devel] [PATCH v4] qemu-char: Fix missed data on unix socket
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH v4] qemu-char: Fix missed data on unix socket |
Date: |
Tue, 21 Jul 2015 09:36:15 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.0.1 |
On 19/07/2015 22:39, address@hidden wrote:
> From: Nils Carlson <address@hidden>
>
> Commit 812c1057 introduced HUP detection on unix and tcp sockets prior
> to a read in tcp_chr_read. This unfortunately broke CloudStack 4.2
> which relied on the old behaviour where data on a socket was readable
> even if a HUP was present.
>
> A working solution is to properly check the return values from recv,
> handling a closed socket once there is no more data to read.
>
> Also enable polling for G_IO_NVAL to ensure the callback is called
> for all possible events as these should now be possible to handle
> with the improved error detection.
>
> Signed-off-by: Nils Carlson <address@hidden>
> ---
> qemu-char.c | 15 +++++++--------
> 1 file changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/qemu-char.c b/qemu-char.c
> index 617e034..3cbfe3e 100644
> --- a/qemu-char.c
> +++ b/qemu-char.c
> @@ -807,7 +807,8 @@ static gboolean io_watch_poll_prepare(GSource *source,
> gint *timeout_)
> }
>
> if (now_active) {
> - iwp->src = g_io_create_watch(iwp->channel, G_IO_IN | G_IO_ERR |
> G_IO_HUP);
> + iwp->src = g_io_create_watch(iwp->channel,
> + G_IO_IN | G_IO_ERR | G_IO_HUP |
> G_IO_NVAL);
> g_source_set_callback(iwp->src, iwp->fd_read, iwp->opaque, NULL);
> g_source_attach(iwp->src, NULL);
> } else {
> @@ -2847,12 +2848,6 @@ 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;
> }
> @@ -2860,7 +2855,11 @@ 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 == EWOULDBLOCK ||
> + errno == EINTR))) {
You need to check socket_error() here instead of errno. Also, EINTR is
not a disconnection. However, I can fix these up for you. I'll send a
pull request.
Paolo
> /* connection closed */
> tcp_chr_disconnect(chr);
> } else if (size > 0) {
>