Re: [RFC/PATCH] avoid SIGPIPE warnings for aliases

Am 10.01.2013 21:22, schrieb Junio C Hamano:

Jeff King [off-list ref] writes:

quoted

Maybe the right rule is "if we are using the shell to execute, do not
mention SIGPIPE"? It seems a little iffy at first, but:

  1. It tends to coincide with direct use of internal tools versus
     external tools.

  2. We do not reliably get SIGPIPE there, anyway, since most shells
     will convert it into exit code 141 before we see it.

I.e., something like:

Hmph.  That may be a good heuristics, but I wonder if we also want
to special case WIFEXITED(status) && WEXITSTATUS(status) == 141 to
pretend as if nothing went wrong, when ignore_sigpipe is in effect?

The purpose of Peff's patch is to remove the error message, but not to
pretend success (the return code remains 141).

I looked at all instances with use_shell=1 or RUN_USING_SHELL:

Most of the time, we do not care where the output of the command goes
to, which I regard as the same case as when a shell runs a command: We
don't need to report the SIGPIPE death.

The interesting cases are when git reads back the output of the command.
Here, a SIGPIPE death of the child would indicate a bug in git, I think,
and some diagnostic would be worth it. But we can just as well declare
that git doesn't have bugs ;)

These are the interesting cases:
connect.c:640:          conn->use_shell = 1;
    a connection to a local repository
convert.c:372:  child_process.use_shell = 1;
    clean/smudge filter
credential.c:216:       helper.use_shell = 1;
    credential helper
diff.c:4851:    child.use_shell = 1;
    textconv

All in all, I think the heuristics makes sense.

-- Hannes