[libvirt] [PATCH 6/7] Check that QEMU is still alive while reading startup output.

[Daniel P. Berrange]

On Tue, Apr 28, 2009 at 11:31:56AM -0400, Cole Robinson wrote:
> By checking the pid every retry period, we can quickly determine if
> the process crashed at startup, rather than make the user wait for
> the entire timeout (3 seconds).

ACK, this looks good.

> ---
>  src/qemu_driver.c |   33 ++++++++++++++++++++++-----------
>  1 files changed, 22 insertions(+), 11 deletions(-)
> 
> diff --git a/src/qemu_driver.c b/src/qemu_driver.c
> index 2f17f6c..04df8ae 100644
> --- a/src/qemu_driver.c
> +++ b/src/qemu_driver.c
> @@ -744,29 +744,40 @@ qemudReadLogOutput(virConnectPtr conn,
>                     int timeout)
>  {
>      int retries = timeout*10;
> +    int got = 0;
>      buf[0] = '\0';
>  
>      while (retries) {
>          ssize_t ret;
> -        size_t got = 0;
> +        int isdead = 0;
>  
> -        while((ret = read(fd, buf+got, buflen-got-1)) > 0) {
> -            got += ret;
> -            buf[got] = '\0';
> -            if ((buflen-got-1) == 0) {
> -                qemudReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
> -                                 _("Out of space while reading %s log output"), what);
> -                return -1;
> -            }
> -        }
> +        if (kill(vm->pid, 0) == -1 && errno == ESRCH)
> +            isdead = 1;
>  
> -        if (ret < 0 && errno != EINTR) {
> +        ret = saferead(fd, buf+got, buflen-got-1);
> +        if (ret < 0) {
>              virReportSystemError(conn, errno,
>                                   _("Failure while reading %s log output"),
>                                   what);
>              return -1;
>          }
>  
> +        got += ret;
> +        buf[got] = '\0';
> +        if (got == buflen-1) {
> +            qemudReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
> +                             _("Out of space while reading %s log output"),
> +                             what);
> +            return -1;
> +        }
> +
> +        if (isdead) {
> +            qemudReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
> +                             _("Process exited while reading %s log output"),
> +                             what);
> +            return -1;
> +        }
> +
>          ret = func(conn, vm, buf, fd);
>          if (ret <= 0)
>              return ret;
> -- 


Daniel
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