Re: bug & patch: exit codes from internal commands are handled incorrectly

> 
> On Dec 18, 2014, at 2:18 PM, Junio C Hamano <gitster@pobox.com> wrote:
> 
>> Kenneth Lorber <keni@his.com> 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?
> 
> Yes.
> 
>> 
>> Your change sweeps such problems under the rug, which is not a
>> healthy thing to do.
> 
> Agreed.  (See below.)
> 
>> 
>> 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().
> 
> The new patch uses 0, 1, and 2 to match diff(1).
> 
>> 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 ;-)
> 
> I'll call that a win.
> 
> The attached patch covers the following:
> - fixes all places where "make test" attempts to call exit() with a value <0 or >255
> - changes git-merge-file.txt to reflect the change in exit codes
> - fixes the exit codes for merge-file
> - adds a warning (which should probably be changed to something clearer) if git.c:run_builtin() is going to cause an out-of-bounds exit
> - fixes a typo in t7007-show.sh
> - replaces return(0) with exit(0) in test-parse-options.c
> 
> The diff is cut against 15598cf41beed0d86cd2ac443e0f69c5a3b40321 (2.3.0-rc2)
> 
> Thanks,
> Keni
> 
> 
> <d2.ship>
>