Re: git fails with a broken pipe when one quits the pager

On 2021-01-31 21:49:49 +0100, Ævar Arnfjörð Bjarmason wrote:

On Sun, Jan 31 2021, Vincent Lefevre wrote:

quoted

FYI, I already have the exit status already in my prompt (the above
commands were just for the example). Still, the git behavior is
disturbing.

Moreover, this doesn't solve the issue when doing something like

  git log && some_other_command

What issue? That we're returning an exit code per getting a SIGHUP here
is a feature. Consider:

    git -c core.pager=/bin/false log && echo showed you the output

If the pager exists with a non-zero exit status, it is normal to
return a non-zero exit status. This was not the bug I reported.

quoted

No! I want to be warned about real SIGPIPEs.

Not being able to write "git log" output is a real SIGPIPE.

Which is not the case here, because the full output has never been
requested by the user.

Is it because in your mind it's got something to do with the "|" shell
piping construct? The SIGPIPE is sent by the kernel, so it's no less
expected in cases like:

    git log && echo foo

Than:

    git log | cat

See the difference (without the patch) between

$ git log && echo foo; echo $?
141

and

$ git log | head; echo $?
[...]
0

[...]

Maybe we have users who'd like to work around zsh's "setopt
PRINT_EXIT_VALUE" mode (would you want this patch if you could make zsh
ignore 141?).

zsh is working as expected, and as I've already said, I ***WANT***
SIGPIPE to be reported by the shell, as it may indicate a real failure
in a script. BTW, I even have a script using git that relies on that:

{ git rev-list --author "$@[-1]" HEAD &&
  git rev-list --grep   "$@[-1]" HEAD } | \
  git "${@[1,-2]:-lv}" --no-walk --stdin

return $((pipestatus[2] ? pipestatus[2] : pipestatus[1]))

Here it is important not to lose any information. No pager is
involved, the full output is needed. If for some reason, the
LHS of the pipe fails due to a SIGPIPE but the right hand side
succeeds, the error will be reported.

The fact is that with a pager, the SIGPIPE with a pager is normal.
Thus with a pager, git is reporting a spurious SIGPIPE, and this
is disturbing.

-- 
Vincent Lefèvre [off-list ref] - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)