[libvirt] [PATCH 2/3] qemu: Ignore libvirt logs when reading QEMU error output

[Osier Yang]

On 23/04/13 00:40, Jiri Denemark wrote:
> When QEMU fails to start, libvirt read its error output and reports it
> back in an error message. However, when libvirtd is configured to log
> debug messages, one would get the following unhelpful garbage:
>
>      virsh # start cd
>      error: Failed to start domain cd
>      error: internal error process exited while connecting to monitor: \
>        2013-04-22 14:24:54.214+0000: 2194219: debug : virFileClose:72 : \
>        Closed fd 21
>      2013-04-22 14:24:54.214+0000: 2194219: debug : virFileClose:72 : \
>        Closed fd 27
>      2013-04-22 14:24:54.215+0000: 2194219: debug : virFileClose:72 : \
>        Closed fd 3
>      2013-04-22 14:24:54.215+0000: 2194220: debug : virExec:602 : Run \
>        hook 0x7feb8f600bf0 0x7feb86ef9300
>      2013-04-22 14:24:54.215+0000: 2194220: debug : qemuProcessHook:2507 \
>        : Obtaining domain lock
>      2013-04-22 14:24:54.216+0000: 2194220: debug : \
>        virDomainLockProcessStart:170 : plugin=0x7feb780261f0 \
>        dom=0x7feb7802a360 paused=1 fd=0x7feb86ef8ec4
>      2013-04-22 14:24:54.216+0000: 2194220: debug : \
>        virDomainLockManagerNew:128 : plugin=0x7feb780261f0 \
>        dom=0x7feb7802a360 withResources=1
>      2013-04-22 14:24:54.216+0000: 2194220: debug : \
>        virLockManagerPluginGetDriver:297 : plugin=0x7feb780261f0
>      2013-04-22 14:24:54.216+0000: 2194220: debug : \
>        virLockManagerNew:321 : driver=0x7feb8ef08640 type=0 nparams=5 \
>        params=0x7feb86ef8d60 flags=0
>      2013-04-22 14:24:54.216+000
>
> instead of (the output with this patch applied):
>
>      virsh # start cd
>      error: Reconnected to the hypervisor
>      error: Failed to start domain cd
>      error: internal error process exited while connecting to monitor: \
>        char device redirected to /dev/pts/33 (label charserial0)
>      qemu-system-x86_64: -drive file=/home/vm/systemrescuecd-x86-1.2.0.\
>        iso,if=none,id=drive-ide0-1-0,readonly=on,format=raw,cache=none: \
>        could not open disk image /home/vm/systemrescuecd-x86-1.2.0.iso: \
>        Permission denied
> ---
>   src/qemu/qemu_process.c | 20 ++++----------------
>   1 file changed, 4 insertions(+), 16 deletions(-)
>
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index a1fbd5f..4988d9b 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -1665,21 +1665,6 @@ static void qemuProcessFreePtyPath(void *payload, const void *name ATTRIBUTE_UNU
>       VIR_FREE(payload);
>   }
>   
> -static void
> -qemuProcessReadLogFD(int logfd, char *buf, int maxlen, int off)
> -{
> -    int ret;
> -    char *tmpbuf = buf + off;
> -
> -    ret = saferead(logfd, tmpbuf, maxlen - off - 1);
> -    if (ret < 0) {
> -        ret = 0;
> -    }
> -
> -    tmpbuf[ret] = '\0';
> -}
> -
> -
>   static int
>   qemuProcessWaitForMonitor(virQEMUDriverPtr driver,
>                             virDomainObjPtr vm,
> @@ -1734,6 +1719,7 @@ cleanup:
>       virHashFree(paths);
>   
>       if (pos != -1 && kill(vm->pid, 0) == -1 && errno == ESRCH) {
> +        int len;
>           /* VM is dead, any other error raised in the interim is probably
>            * not as important as the qemu cmdline output */
>           if (virQEMUCapsUsedQMP(qemuCaps)) {
> @@ -1745,7 +1731,9 @@ cleanup:
>                   goto closelog;
>               }
>           }
> -        qemuProcessReadLogFD(logfd, buf, buf_size, strlen(buf));
> +
> +        len = strlen(buf);
> +        qemuProcessReadLog(logfd, buf + len, buf_size - len - 1, 0);
>           virReportError(VIR_ERR_INTERNAL_ERROR,
>                          _("process exited while connecting to monitor: %s"),
>                          buf);

ACK