Re: [PATCH] sub-process: print the cmd when a capability is unsupported

> In handshake_capabilities() we use warning() when a capability
> is not supported, so the exit code of the function is 0 and no
> further error is shown. This is a problem because the warning
> message doesn't tell us which subprocess cmd failed.
> 
> On the contrary if we cannot write a packet from this function,
> we use error() and then subprocess_start() outputs:
> 
>      initialization for subprocess '<cmd>' failed
> 
> so we can know which subprocess cmd failed.
> 
> Let's improve the warning() message, so that we can know which
> subprocess cmd failed.
> 
> Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
> ---
>   sub-process.c | 13 ++++++++-----
>   1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/sub-process.c b/sub-process.c
> index 6edb97c1c6..6b133f8dce 100644
> --- a/sub-process.c
> +++ b/sub-process.c
> @@ -158,7 +158,8 @@ static int handshake_version(struct child_process *process,
>   
>   static int handshake_capabilities(struct child_process *process,
>   				  struct subprocess_capability *capabilities,
> -				  unsigned int *supported_capabilities)
> +				  unsigned int *supported_capabilities,
> +				  const char *cmd)
>   {
>   	int i;
>   	char *line;
> @@ -184,8 +185,8 @@ static int handshake_capabilities(struct child_process *process,
>   			if (supported_capabilities)
>   				*supported_capabilities |= capabilities[i].flag;
>   		} else {
> -			warning("external filter requested unsupported filter capability '%s'",
> -				p);
> +			warning("subprocess '%s' requested unsupported capability '%s'",
> +				cmd, p);
>   		}
>   	}
>   
> @@ -206,8 +207,10 @@ int subprocess_handshake(struct subprocess_entry *entry,
>   
>   	retval = handshake_version(process, welcome_prefix, versions,
>   				   chosen_version) ||
> -		 handshake_capabilities(process, capabilities,
> -					supported_capabilities);
> +		 handshake_capabilities(process,
> +					capabilities,
> +					supported_capabilities,
> +					entry->cmd);
>   
>   	sigchain_pop(SIGPIPE);
>   	return retval;
>