[Crash-utility] __error() mucks with pc->tmpfile

[Dave Anderson]

----- Original Message -----
> I spent today trying to figure out why some parsing was going awry.
> The problem stems from trying to emit a warning message while
> reprocessing the pc->tmpfile data.  viz.:
> 
> 
>         open_tmpfile();
>         hq_open();
>         count = do_list(&ld);
>         hq_close();
>         rewind(pc->tmpfile);
> 	while (fgets(buf, sizeof(buf), pc->tmpfile) != 0) {
> 		if (something_wrong(buf)) {
> 			error(WARNING, "something wrong");
> 			continue;
> 		}
> 	... etc.
> 
> After the error() invocation, the data have been scribbled on because
> of this code:
>         if ((fp != stdout) && (fp != pc->stdpipe)) {
>                 fprintf(fp, "%s%s%s %s", new_line ? "\n" : "",
> 			type == WARNING ? "WARNING" :
> 			type == NOTE ? "NOTE" :
> 			type == CONT ? spacebuf : pc->curcmd,
> 			type == CONT ? " " : ":",
> 			buf);
> 		fflush(fp);
> 	}
> 
> "fp" being a global variable that is set to pc->tmpfile.
> I suppose you can say, "works as expected", but it surely isn't as
> I would expect.  How about a nice "standard_error" wrapper that
> hides and restores that "fp" global variable thingy while invoking
> __error()?  I can do it myself, but I really do not think it
> advisable for crash client code to fiddle with what seems to me
> to be internal state.
> 
> Thanks! - Bruce

Right -- I would never expect error() to be called while inside 
an open_tmpfile() operation.  Normally the behind-the-scenes data
is parsed, and if anything is to be displayed while open_tmpfile()
is still in play, it would be fprint()'ed using pc->saved_fp.  

So I'm not sure what the best way to handle your client code
that does just that.  I haven't tested it, but as I understand
it, you would see the error message printed both to stdout (from
the else part of the if-else code above the code segment you show
above), and then again in your overwritten/parsed code.  If that's
true, then I guess there should just be a prevention of the 
secondary output above if pc->tmpfile is in play.

Dave