Re: [PATCH] bpftool: Try to read btf as raw data if elf read fails

Jakub Kicinski
2019-10-21T23:16:05Z

On Mon, 21 Oct 2019 16:02:27 +0200, Jiri Olsa wrote:
> > > static int do_dump(int argc, char **argv)
> > > {
> > > struct btf *btf = NULL;
> > > @@ -397,7 +429,7 @@ static int do_dump(int argc, char **argv)
> > > __u32 btf_id = -1;
> > > const char *src;
> > > int fd = -1;
> > > - int err;
> > > + int err = 0;
> >
> > This change looks unnecessary.
>
> I'm getting confusing warnings from gcc about this,
> but there is a code path where do_dump would return
> untouched err:
>
> do_dump
> int err;
>
> } else if (is_prefix(src, "file")) {
> btf = btf__parse_elf(*argv, NULL); // succeeds
>
> }
>
> while (argc) {
> if (is_prefix(*argv, "format")) {
> else { // in here
> goto done;
> }
>
> done:
> return err;

ugh, right those look legit, although unrelated to you change.

err should always be set before jumping to 'done'. The error
setting in this function looks super messy :( Sometimes is returns
errno codes, sometimes positive values, sometimes negative, sometimes
just -1. Sometimes it jumps to 'done' for no good reason, ahh :/