Re: [PATCH v2 7/8] sigwaittest.c: Check return values of write() and ftruncate()

[John Kacur <jkacur@redhat.com>]

On Sat, 26 Jul 2025, Cheng-Yang Chou wrote:

> Add error handling for write() to tracefs and ftruncate() on shared memory
> to avoid ignoring errors.
> 
> Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
> ---
>  src/sigwaittest/sigwaittest.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/src/sigwaittest/sigwaittest.c b/src/sigwaittest/sigwaittest.c
> index 026cc81..3944b54 100644
> --- a/src/sigwaittest/sigwaittest.c
> +++ b/src/sigwaittest/sigwaittest.c
> @@ -72,6 +72,7 @@ void *semathread(void *param)
>  	cpu_set_t mask;
>  	int policy = SCHED_FIFO;
>  	struct sched_param schedp;
> +	int ret;
>  
>  	memset(&schedp, 0, sizeof(schedp));
>  	schedp.sched_priority = par->priority;
> @@ -168,7 +169,10 @@ void *semathread(void *param)
>  				int tracing_enabled =
>  				    open(tracing_enabled_file, O_WRONLY);
>  				if (tracing_enabled >= 0) {
> -					write(tracing_enabled, "0", 1);
> +					ret = write(tracing_enabled, "0", 1);
> +					if (ret < 0)
> +						fatal("Could not write to %s: %s\n",
> +						      tracing_enabled_file, strerror(errno));
>  					close(tracing_enabled);
>  				} else
>  					fatal("Could not access %s\n",
> @@ -489,7 +493,12 @@ int main(int argc, char *argv[])
>  			fprintf(stderr, "Could not create shared memory\n");
>  			return 1;
>  		}
> -		ftruncate(shmem, totalsize);
> +		if (ftruncate(shmem, totalsize) == -1) {
> +			perror("ftruncate failed");
> +			close(shmem);
> +			shm_unlink("/sigwaittest");
> +			return 1;
> +		}
>  		param = mmap(0, totalsize, PROT_READ|PROT_WRITE, MAP_SHARED,
>  		    shmem, 0);
>  		if (param == MAP_FAILED) {
> -- 
> 2.48.1
> 
> 
> 
Signed-off-by: John Kacur <jkacur@redhat.com>