From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Enzo Matsumiya <ematsumiya@suse.de>
Cc: Junio C Hamano <gitster@pobox.com>, Jeff King <peff@peff.net>,
git@vger.kernel.org
Subject: Re: [PATCH v2] pager: fix crash when pager program doesn't exist
Date: Mon, 22 Nov 2021 18:10:47 +0100 [thread overview]
Message-ID: <211122.861r38yuun.gmgdl@evledraar.gmail.com> (raw)
In-Reply-To: <20211122164635.6zrqjqow4xa7idnn@cyberdelia>
On Mon, Nov 22 2021, Enzo Matsumiya wrote:
> On 11/22, Ævar Arnfjörð Bjarmason wrote:
>>I think an alternate direction of simply getting rid of "argv" is better
>>in this case, and I've just submitted a topic to do that:
>>https://lore.kernel.org/git/cover-0.5-00000000000-20211122T153605Z-avarab@gmail.com/
>
> Well, this is my first interaction with git's source, so I can't say for
> sure, but that solution seems more complete indeed.
>
>>It still leave us with this oddity:
>>
>> $ ~/g/git/git -c pager.show=INVALID_PAGER show HEAD
>> error: cannot run INVALID_PAGER: No such file or directory
>> error: cannot run INVALID_PAGER: No such file or directory
>>
>>But that was the case before that topic (if we hadn't
>>crashed/segfaulted), and with your proposed change here.
>
> Yes, I did find it weird on my initial debugging, but didn't care at
> first.
>
> Now, looking again, it's because git (main command) have a higher
> precedence on pager preference, so it tries to setup/run the pager
> before running subcommands.
>
> An issue I've hit now is, if we don't want to fallback to any other
> setting, this works:
>
> diff --git a/pager.c b/pager.c
> index d93304527d62..b528bbd644b5 100644
> --- a/pager.c
> +++ b/pager.c
> @@ -110,6 +110,14 @@ void setup_pager(void)
> if (!pager)
> return;
>
> + /*
> + * There's already a pager set up and running.
> + * Regardless if it was successful or not, we shouldn't try running
> + * it again.
> + */
> + if (pager_in_use())
> + return;
> +
> /*
> * After we redirect standard output, we won't be able to use an ioctl
> * to get the terminal size. Let's grab it now, and then set $COLUMNS
>
> However, IMHO it would make sense to try pager.<subcommand> if a
> previous attempt failed, e.g.:
>
> $ git config pager.show my-valid-pager
> $ GIT_PAGER=invalid-pager git -p show
>
> So this will first try invalid-pager, fail, and not try again, with the
> above patch. As a user, I would expect that my-valid-pager to be run in
> case invalid-pager failed.
>
> What do you think?
I think a better approach is to just die early and not fallback if the
user's pager setting is broken. I.e. let's not second-guess their
explicit configuration, trust it, and if it doesn't work die() or
error().
We do fallback on emitting to stdout, so perhaps there's a reason to do
more exhaustive fallbacks here, I'm not really sure about the above.
The use of pager_in_use() in the above patch smells iffy though, we're
able to do that because we did the setenv() of GIT_PAGER_IN_USE=true.
We then use that to check if we set it up ourselves and skip setting it
up, but any other program invoked by us will be fooled by
GIT_PAGER_IN_USE=true. Maybe that's intentional, but won't we then
expect a working pager in some cases (maybe not)...
It seems non-obvious at best, perhaps we should push a list of failed
pagers, or just the one failed one if we're not doing fallbacks..
Presumably we can invoke N git <something>, where those <something> have
different pager.<something> config...
next prev parent reply other threads:[~2021-11-22 17:16 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-20 19:40 [PATCH v2] pager: fix crash when pager program doesn't exist Enzo Matsumiya
2021-11-21 18:37 ` Jeff King
2021-11-22 2:10 ` Junio C Hamano
2021-11-22 4:35 ` Jeff King
2021-11-22 14:52 ` Enzo Matsumiya
2021-11-22 17:05 ` Junio C Hamano
2021-11-23 16:40 ` Enzo Matsumiya
2021-11-24 1:55 ` Ævar Arnfjörð Bjarmason
2021-11-24 15:51 ` Jeff King
2021-11-22 16:04 ` [PATCH 0/5] run-command API: get rid of "argv" Ævar Arnfjörð Bjarmason
2021-11-22 16:04 ` [PATCH 1/5] archive-tar: use our own cmd.buf in error message Ævar Arnfjörð Bjarmason
2021-11-22 21:04 ` Junio C Hamano
2021-11-22 16:04 ` [PATCH 2/5] upload-archive: use regular "struct child_process" pattern Ævar Arnfjörð Bjarmason
2021-11-22 17:02 ` Jeff King
2021-11-22 20:53 ` Ævar Arnfjörð Bjarmason
2021-11-22 21:10 ` Jeff King
2021-11-22 21:36 ` Ævar Arnfjörð Bjarmason
2021-11-22 16:04 ` [PATCH 3/5] run-command API users: use strvec_pushv(), not argv assignment Ævar Arnfjörð Bjarmason
2021-11-22 21:19 ` Junio C Hamano
2021-11-22 21:30 ` Ævar Arnfjörð Bjarmason
2021-11-22 16:04 ` [PATCH 4/5] run-command API users: use strvec_pushl(), not argv construction Ævar Arnfjörð Bjarmason
2021-11-22 16:04 ` [PATCH 5/5] run-command API: remove "argv" member, always use "args" Ævar Arnfjörð Bjarmason
2021-11-22 17:32 ` Jeff King
2021-11-22 18:19 ` Ævar Arnfjörð Bjarmason
2021-11-22 18:47 ` Jeff King
2021-11-22 17:52 ` [PATCH 0/5] run-command API: get rid of "argv" Jeff King
2021-11-22 18:11 ` Junio C Hamano
2021-11-22 18:33 ` Ævar Arnfjörð Bjarmason
2021-11-22 18:49 ` Jeff King
2021-11-22 18:26 ` Ævar Arnfjörð Bjarmason
2021-11-23 12:06 ` [PATCH v2 0/9] run-command API: get rid of "argv" and "env" Ævar Arnfjörð Bjarmason
2021-11-23 12:06 ` [PATCH v2 1/9] worktree: remove redundant NULL-ing of "cp.argv Ævar Arnfjörð Bjarmason
2021-11-23 15:26 ` Eric Sunshine
2021-11-24 1:54 ` Junio C Hamano
2021-11-24 6:00 ` Eric Sunshine
2021-11-24 6:12 ` Eric Sunshine
2021-11-24 5:44 ` Eric Sunshine
2021-11-23 12:06 ` [PATCH v2 2/9] upload-archive: use regular "struct child_process" pattern Ævar Arnfjörð Bjarmason
2021-11-23 12:06 ` [PATCH v2 3/9] run-command API users: use strvec_pushv(), not argv assignment Ævar Arnfjörð Bjarmason
2021-11-23 12:06 ` [PATCH v2 4/9] run-command tests: " Ævar Arnfjörð Bjarmason
2021-11-24 1:33 ` Eric Sunshine
2021-11-23 12:06 ` [PATCH v2 5/9] run-command API users: use strvec_pushl(), not argv construction Ævar Arnfjörð Bjarmason
2021-11-23 12:06 ` [PATCH v2 6/9] run-command API users: use strvec_push(), " Ævar Arnfjörð Bjarmason
2021-11-23 12:06 ` [PATCH v2 7/9] run-command API: remove "argv" member, always use "args" Ævar Arnfjörð Bjarmason
2021-11-23 12:06 ` [PATCH v2 8/9] difftool: use "env_array" to simplify memory management Ævar Arnfjörð Bjarmason
2021-11-23 12:06 ` [PATCH v2 9/9] run-command API: remove "env" member, always use "env_array" Ævar Arnfjörð Bjarmason
2021-11-25 22:52 ` [PATCH v3 0/9] run-command API: get rid of "argv" and "env" Ævar Arnfjörð Bjarmason
2021-11-25 22:52 ` [PATCH v3 1/9] worktree: stop being overly intimate with run_command() internals Ævar Arnfjörð Bjarmason
2021-11-26 9:48 ` Eric Sunshine
2021-11-25 22:52 ` [PATCH v3 2/9] upload-archive: use regular "struct child_process" pattern Ævar Arnfjörð Bjarmason
2021-11-25 22:52 ` [PATCH v3 3/9] run-command API users: use strvec_pushv(), not argv assignment Ævar Arnfjörð Bjarmason
2021-11-25 22:52 ` [PATCH v3 4/9] run-command tests: " Ævar Arnfjörð Bjarmason
2021-11-25 22:52 ` [PATCH v3 5/9] run-command API users: use strvec_pushl(), not argv construction Ævar Arnfjörð Bjarmason
2021-11-25 22:52 ` [PATCH v3 6/9] run-command API users: use strvec_push(), " Ævar Arnfjörð Bjarmason
2021-11-25 22:52 ` [PATCH v3 7/9] run-command API: remove "argv" member, always use "args" Ævar Arnfjörð Bjarmason
2021-11-25 22:52 ` [PATCH v3 8/9] difftool: use "env_array" to simplify memory management Ævar Arnfjörð Bjarmason
2021-11-25 22:52 ` [PATCH v3 9/9] run-command API: remove "env" member, always use "env_array" Ævar Arnfjörð Bjarmason
2021-11-22 15:31 ` [PATCH v2] pager: fix crash when pager program doesn't exist Enzo Matsumiya
2021-11-22 16:22 ` Ævar Arnfjörð Bjarmason
2021-11-22 16:46 ` Enzo Matsumiya
2021-11-22 17:10 ` Ævar Arnfjörð Bjarmason [this message]
2021-11-22 17:41 ` Jeff King
2021-11-22 18:00 ` Junio C Hamano
2021-11-22 18:26 ` Jeff King
2021-11-22 17:55 ` Junio C Hamano
2021-11-22 18:19 ` Junio C Hamano
2021-11-22 18:37 ` Jeff King
2021-11-22 20:39 ` Junio C Hamano
2021-11-22 17:08 ` Junio C Hamano
2021-11-22 18:35 ` Ævar Arnfjörð Bjarmason
2021-11-22 16:30 ` Jeff King
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