Re: [PATCH] test-lib.sh: work around ksh's trap shortcomings

From: Brandon Casey <casey@nrlssc.navy.mil>
Date: Aug 19, 2008, 14:59 UTC
Message-ID: <nRhBKqCwHxZZH8zh17SOnUKHFp0V5HZj8_Lcmybj49DM7L4TYYoZbQ@cipher.nrlssc.navy.mil>
In-Reply-To: <7v3al1h2rk.fsf@gitster.siamese.dyndns.org>

Junio C Hamano wrote:

> Yeah, I think I got the subtle distinction between [PATCH FYI], [PATCH]
> and ones with and without sign-offs.

Heh, so subtle as to be unintentional. I think I mucked up that posting. I should have labeled them all FYI and numbered them. I did hope there would be some discussion that would result in a followup patch for submission.

> I've read "trap" section of 1003.1 2004 three times but I do not see the
> exact definition of "EXIT" condition mentioned.  Is the behaviour to
> consider "function return" the EXIT condition considered a "shortcoming"
> (aka bug)?

No, I think it is the defined behavior for the Korn shell.

The SunOS 5.7 man page states:

     If sig  is  0 or EXIT and the trap  statement is exe-
     cuted inside the body of a function, then the com-
     mand arg is executed after the function completes.
     If sig is 0 or EXIT for a trap   set  outside  any
     function, the command arg is executed on exit from
     the shell.

The IRIX 6.5 man page has the exact same wording.

On linux, the man page for the public domain Korn shell states

    Functions  defined with the function reserved word are treated differ-
    ently in the following ways from functions defined with the  ()  nota-
    tion:

...

      - The EXIT trap, if set in a function, will be executed after the
        function returns.

But then later in the trap section:

    The original Korn shell’s DEBUG trap and the  handling  of  ERR
    and EXIT traps in functions are not yet implemented.

If Korn shell is to be supported, it seems that trap on EXIT must be avoided within functions. I think the only one is in git-bisect.

-brandon