Re: [PATCH 1/1] qemurunner: Improves checking for Server and Target IPs on qemus parameters

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Wed, 2015-08-05 at 23:21 +0000, Alejandro Hernandez wrote:
> Fixes server hanging infinitely waiting for qemus process to let go of bitbake.lock
> 
> Signed-off-by: Alejandro Hernandez <alejandro.hernandez@linux.intel.com>
> ---
>  meta/lib/oeqa/utils/qemurunner.py | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/meta/lib/oeqa/utils/qemurunner.py b/meta/lib/oeqa/utils/qemurunner.py
> index 1cf8f76..ff53af3 100644
> --- a/meta/lib/oeqa/utils/qemurunner.py
> +++ b/meta/lib/oeqa/utils/qemurunner.py
> @@ -120,14 +120,17 @@ class QemuRunner:
>              cmdline = ''
>              with open('/proc/%s/cmdline' % self.qemupid) as p:
>                  cmdline = p.read()
> -            ips = re.findall("((?:[0-9]{1,3}\.){3}[0-9]{1,3})", cmdline.split("ip=")[1])
> -            if not ips or len(ips) != 3:
> +	    try:
> +                ips = re.findall("((?:[0-9]{1,3}\.){3}[0-9]{1,3})", cmdline.split("ip=")[1])
> +                if not ips or len(ips) != 3:
> +	            raise Exception
> +                else:
> +                    self.ip = ips[0]
> +                    self.server_ip = ips[1]
> +	    except Exception:
>                  logger.info("Couldn't get ip from qemu process arguments! Here is the qemu command line used: %s" % cmdline)
>                  self.stop()
>                  return False
> -            else:
> -                self.ip = ips[0]
> -                self.server_ip = ips[1]
>              logger.info("Target IP: %s" % self.ip)
>              logger.info("Server IP: %s" % self.server_ip)
>              logger.info("Waiting at most %d seconds for login banner" % self.boottime)

This is ok, however its not as pythonic as perhaps it could/should be.
Usually with python you should always trap specific exceptions, so in
this case you'd do:

try:
    y = x[1]
    if len(ips) != 3:
        raise ValueError
except IndexError, ValueError:
    <handle error>

You do this so that if something unexpected happens, the code doesn't
"swallow" the error but shows a complete traceback and failure.

The whitespace on this patch also looks a little bit odd although I
didn't try applying the patch.

Cheers,

Richard