Re: [PATCH bpf-next v3 2/3] bpftool: fix spurious batch file read error

> diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
> index c91e1a6e1a1e..c9a86039c400 100644
> --- a/tools/bpf/bpftool/main.c
> +++ b/tools/bpf/bpftool/main.c

[ ... ]

> @@ -429,7 +430,10 @@ static int do_batch(int argc, char **argv)
>  		lines++;
>  	}
>
> -	if (errno && errno != ENOENT) {
> +	if (line_too_long) {
> +		p_err("reading batch file failed: %s", strerror(E2BIG));
> +		err = -1;
> +	} else if (ferror(fp)) {
>  		p_err("reading batch file failed: %s", strerror(errno));
>  		err = -1;
>  	} else {

[ ... ]

This isn't a bug, but now that the batch read check uses ferror() rather
than errno, is the USE_LIBCAP errno = 0 reset in main() still needed?

Looking at main():

#ifdef USE_LIBCAP
	/* Libcap < 2.63 hooks before main() to compute the number of
	 * capabilities of the running kernel, and doing so it calls prctl()
	 * which may fail and set errno to non-zero.
	 * Let's reset errno to make sure this does not interfere with the
	 * batch mode.
	 */
	errno = 0;
#endif

The comment says the reset is specifically to prevent interference with
batch mode, but do_batch() no longer checks errno to detect read failures.
Could this block be dropped alongside the ferror() change?


---
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