Re: [PATCH] candump: add option to ignore ENOBUFS

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 10/26/2012 11:42 AM, yegorslists@googlemail.com wrote:
> From: Yegor Yefremov <yegorslists@googlemail.com>
> 
> -f option replicated -i option from cangen and allows to
> ignore ENOBUFS error in bridge mode

Better not ignore, but handle the error. If socket would support, wait
with select/poll that the socket get writable and try again. For now
sleep and try again. (or fix the poll/select bug in the kernel).

Marc

> Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
> ---
>  candump.c |   19 ++++++++++++++++---
>  1 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/candump.c b/candump.c
> index ac51192..3a6be62 100644
> --- a/candump.c
> +++ b/candump.c
> @@ -53,6 +53,7 @@
>  #include <ctype.h>
>  #include <libgen.h>
>  #include <time.h>
> +#include <errno.h>
>  
>  #include <sys/time.h>
>  #include <sys/types.h>
> @@ -122,6 +123,7 @@ void print_usage(char *prg)
>  	fprintf(stderr, "         -r <size>   (set socket receive buffer to <size>)\n");
>  	fprintf(stderr, "         -d          (monitor dropped CAN frames)\n");
>  	fprintf(stderr, "         -e          (dump CAN error frames in human-readable format)\n");
> +	fprintf(stderr, "         -f          (ignore -ENOBUFS return values on write() syscalls)\n");
>  	fprintf(stderr, "\n");
>  	fprintf(stderr, "Up to %d CAN interfaces with optional filter sets can be specified\n", MAXSOCK);
>  	fprintf(stderr, "on the commandline in the form: <ifname>[,filter]*\n");
> @@ -211,6 +213,7 @@ int main(int argc, char **argv)
>  	unsigned char view = 0;
>  	unsigned char log = 0;
>  	unsigned char logfrmt = 0;
> +	unsigned char ignore_enobufs = 0;
>  	int count = 0;
>  	int rcvbuf_size = 0;
>  	int opt, ret;
> @@ -236,7 +239,7 @@ int main(int argc, char **argv)
>  	last_tv.tv_sec  = 0;
>  	last_tv.tv_usec = 0;
>  
> -	while ((opt = getopt(argc, argv, "t:ciaSs:b:B:u:ldLn:r:he?")) != -1) {
> +	while ((opt = getopt(argc, argv, "ft:ciaSs:b:B:u:ldLn:r:he?")) != -1) {
>  		switch (opt) {
>  		case 't':
>  			timestamp = optarg[0];
> @@ -347,6 +350,10 @@ int main(int argc, char **argv)
>  			}
>  			break;
>  
> +		case 'f':
> +			ignore_enobufs = 1;
> +			break;
> +
>  		default:
>  			print_usage(basename(argv[0]));
>  			exit(1);
> @@ -625,8 +632,14 @@ int main(int argc, char **argv)
>  
>  					nbytes = write(bridge, &frame, sizeof(struct can_frame));
>  					if (nbytes < 0) {
> -						perror("bridge write");
> -						return 1;
> +						if (errno != ENOBUFS) {
> +							perror("bridge write");
> +							return 1;
> +						}
> +						if (!ignore_enobufs) {
> +							perror("bridge write");
> +							return 1;
> +						}
>  					} else if ((size_t)nbytes < sizeof(struct can_frame)) {
>  						fprintf(stderr,"bridge write: incomplete CAN frame\n");
>  						return 1;
> 


-- 
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