On Dec 18, 2014, at 2:18 PM, Junio C Hamano <gitster@xxxxxxxxx> wrote:
> Kenneth Lorber <keni@xxxxxxx> writes:
>
>>> Bug: exit codes from (at least) internal commands are handled incorrectly.
>>> E.g. git-merge-file, docs say:
>>> The exit value of this program is negative on error, and the number of
>>> conflicts otherwise. If the merge was clean, the exit value is 0.
>>> But only 8 bits get carried through exit, so 256 conflicts gives
>>> exit(0), which means the merge was clean.
>
> Wouldn't any cmd_foo() that returns negative to main() be buggy?
Absolutely.
> Your change sweeps such problems under the rug, which is not a
> healthy thing to do.
True. But as I don’t know the codebase it seemed the safe thing to do
at least to prove the bug existed before filing a bug report.
> Expecting that the exit code can signal small positive integers and
> other generic kinds of failures is a losing proposition. I think it
> is a better fix to update cmd_merge_file() to return 1 (when ret is
> positive), 0 (when ret is zero) or 128 (when ret is negative), or
> something simple like that, and update the documentation to match
> that, without touching git.c::main().
I agree.
It does leave open the question of whether this bit of information
is of any use and should/could be reported out in another way. It’s not
to me, so I won’t be proposing anything to address that.
> Among the in-tree users, I notice git-cvsserver.perl is already
> using the command incorrectly. It does this:
>
> my $return = system("git", "merge-file", $file_local, $file_old, $file_new);
> $return >>= 8;
>
> cleanupTmpDir();
>
> if ( $return == 0 )
> {
> $log->info("Merged successfully");
> ...
> }
> elsif ( $return == 1 )
> {
> $log->info("Merged with conflicts");
> ...
> }
> else
> {
> $log->warn("Merge failed");
> next;
> }
>
> which assumes $return == 1 is special "half-good", which is not
> consistent with the documented interface. It will incorrectly
> say "Merge failed" when there are two or more conflicts.
>
> And with such a "1 or 0 or -1" change, you will fix that caller as
> well ;-)
Yay! :-)
Thanks,
Keni
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