[Libguestfs] [PATCH 1/5] daemon error handling: Clear errno before calling stub functions.

[Matthew Booth]

On 30/11/09 14:42, Richard W.M. Jones wrote:
>
>> From bad45d57b816c3734bcbf5f92a707fc1ff112c1c Mon Sep 17 00:00:00 2001
> From: Richard Jones<rjones at redhat.com>
> Date: Mon, 30 Nov 2009 13:55:04 +0000
> Subject: [PATCH 1/5] daemon error handling: Clear errno before calling stub functions.
>
> This just ensures that we accurately report errors, even if our
> error path code doesn't set errno.  We won't end up with a bogus
> errno left over from a previous call.
> ---
>   daemon/proto.c |   17 ++++++++++++++++-
>   1 files changed, 16 insertions(+), 1 deletions(-)
>
> diff --git a/daemon/proto.c b/daemon/proto.c
> index 2231037..e3ff9e9 100644
> --- a/daemon/proto.c
> +++ b/daemon/proto.c
> @@ -29,6 +29,10 @@
>   #include<rpc/types.h>
>   #include<rpc/xdr.h>
>
> +#ifdef HAVE_WINDOWS_H
> +#include<windows.h>
> +#endif
> +
>   #include "c-ctype.h"
>   #include "ignore-value.h"
>
> @@ -137,9 +141,20 @@ main_loop (int _sock)
>         goto cont;
>       }
>
> -    /* Now start to process this message. */
>       proc_nr = hdr.proc;
>       serial = hdr.serial;
> +
> +    /* Clear errors before we call the stub functions.  This is just
> +     * to ensure that we can accurately report errors in cases where
> +     * error handling paths don't set errno correctly.
> +     */
> +    errno = 0;
> +#ifdef WIN32
> +    SetLastError (0);
> +    WSASetLastError (0);
> +#endif
> +
> +    /* Now start to process this message. */
>       dispatch_incoming_message (&xdr);
>       /* Note that dispatch_incoming_message will also send a reply. */
>
> -- 1.6.5.2

Looks safe. ACK.

Incidentally, what's returning success but still setting an error code 
which requires this?

Matt
-- 
Matthew Booth, RHCA, RHCSS
Red Hat Engineering, Virtualisation Team

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