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

On Mon, 21 Oct 2019 16:02:27 +0200, Jiri Olsa wrote:

quoted

quoted

 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 :/