[libvirt] [PATCH 1/4] qemu: fix wrong errno report in qemuMonitorOpenUnix

[Eric Blake]

On 07/15/2014 02:32 AM, Jincheng Miao wrote:
> In qemuMonitorOpenUnix, after connect(), virProcessKill will be
> invoked when cpid is not empty. But if the qemu-kvm process exited
> early, virProcessKill will flush errno as ESRCH, so the wrong
> message will be recorded in log as:
> error: qemuMonitorOpenUnix:309 : failed to connect to monitor socket: No such process
> 
> After patched:
> error : qemuMonitorOpenUnix:312 : failed to connect to monitor socket: Connection refused
> 
> Signed-off-by: Jincheng Miao <jmiao at redhat.com>
> ---
>  src/qemu/qemu_monitor.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
> index db3dd73..c8284fe 100644
> --- a/src/qemu/qemu_monitor.c
> +++ b/src/qemu/qemu_monitor.c
> @@ -293,19 +293,22 @@ qemuMonitorOpenUnix(const char *monitor, pid_t cpid)
>      }
>  
>      do {
> +        int orig_errno;
>          ret = connect(monfd, (struct sockaddr *) &addr, sizeof(addr));
>  
>          if (ret == 0)
>              break;
>  
> -        if ((errno == ENOENT || errno == ECONNREFUSED) &&
> +        orig_errno = errno;
> +
> +        if ((orig_errno == ENOENT || orig_errno == ECONNREFUSED) &&
>              (!cpid || virProcessKill(cpid, 0) == 0)) {

virProcessKill can be called on cleanup paths. I think it might be wiser
to rewrite virProcessKill() to guarantee that it does not modify errno
than it is to make all callers have to store a temporary.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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