From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-20.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 406BAC48BE5 for ; Thu, 17 Jun 2021 02:20:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1291A613B9 for ; Thu, 17 Jun 2021 02:20:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231383AbhFQCWc (ORCPT ); Wed, 16 Jun 2021 22:22:32 -0400 Received: from pb-smtp2.pobox.com ([64.147.108.71]:62347 "EHLO pb-smtp2.pobox.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230155AbhFQCWb (ORCPT ); Wed, 16 Jun 2021 22:22:31 -0400 Received: from pb-smtp2.pobox.com (unknown [127.0.0.1]) by pb-smtp2.pobox.com (Postfix) with ESMTP id 93013D88B0; Wed, 16 Jun 2021 22:20:24 -0400 (EDT) (envelope-from junio@pobox.com) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed; d=pobox.com; h=from:to:cc :subject:references:date:in-reply-to:message-id:mime-version :content-type; s=sasl; bh=xNqZSQxLjYrINpcooychYLh46tB+2ebgydBL+G pG/cE=; b=qFR7zs34g+ZmvEmhLfj5pQKt6AzjgIzw4wbP/NYg05Kb1eLdUZh7Ls Eo7oGXPFT6n7d2aC/wAuoSQLDFkVumj8D1OXdephhm36GPbxPrGXRcHLnbaWOUfN yj9fiW/zJMeGHZlRs221JeOYYaphLAO1MZ1X64YdkHfikWQyeTA0s= Received: from pb-smtp2.nyi.icgroup.com (unknown [127.0.0.1]) by pb-smtp2.pobox.com (Postfix) with ESMTP id 7810FD88AE; Wed, 16 Jun 2021 22:20:24 -0400 (EDT) (envelope-from junio@pobox.com) Received: from pobox.com (unknown [104.196.36.241]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by pb-smtp2.pobox.com (Postfix) with ESMTPSA id AD4C8D88AD; Wed, 16 Jun 2021 22:20:23 -0400 (EDT) (envelope-from junio@pobox.com) From: Junio C Hamano To: "Johannes Schindelin via GitGitGadget" Cc: git@vger.kernel.org, Johannes Schindelin Subject: Re: [PATCH v2] pager: do not unnecessarily set COLUMNS on Windows References: Date: Thu, 17 Jun 2021 11:20:22 +0900 In-Reply-To: (Johannes Schindelin via GitGitGadget's message of "Wed, 16 Jun 2021 12:38:11 +0000") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Pobox-Relay-ID: 9262ACDA-CF12-11EB-9F3B-FD8818BA3BAF-77302942!pb-smtp2.pobox.com Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org "Johannes Schindelin via GitGitGadget" writes: > From: Johannes Schindelin > > Since https://github.com/gwsw/less/commit/bb0ee4e76c2, `less` prefers > the `COLUMNS` variable over asking ncurses itself. > > This is typically not a problem because we ask `TIOCGWINSZ` in Git, to > determine the correct value for `COLUMNS`, and then set that environment > variable. > > However, on Windows it _is_ a problem. The reason is that Git for > Windows uses a version of `less` that relies on the MSYS2 runtime to > interact with the pseudo terminal (typically inside a MinTTY window, > which is also aware of the MSYS2 runtime). Both MinTTY and `less.exe` > interact with that pseudo terminal via `ioctl()` calls (which the MSYS2 > runtime emulates even if there is no such thing on Windows). > > But `git.exe` itself is _not_ aware of the MSYS2 runtime, or for that > matter of that pseudo terminal, and has no way to call `ioctl()` or > `TIOCGWINSZ`. > > Therefore, `git.exe` will fall back to hard-coding 80 columns, no matter > what the actual terminal size is. > > But `less.exe` is totally able to interact with the MSYS2 runtime and > would not actually require Git's help (which actually makes things > worse here). So let's not override `COLUMNS` on Windows. > > Note: we do this _only_ on Windows, and _only_ if `TIOCGWINSZ` is not > defined, to reduce any potential undesired fall-out from this patch. > > This fixes https://github.com/git-for-windows/git/issues/3235 > > Signed-off-by: Johannes Schindelin > --- > pager: do not unnecessarily set COLUMNS on Windows > > A recent upgrade of the "less" package in Git for Windows causes > problems. Here is a work-around. > > Changes since v1: > > * The commit message was reworded to clarify the underlying issue > better. Thanks for an updated log message to clarify the problem description. I think treating this as "less" specific band-aid is OK, but I do not think tying this to Windows is a good design choice. The guiding principle for this change is more like "if we do not know and cannot learn the true value, internally assuming 80-columns as a last resort fallback may be OK, but do not export it for consumption for other people---they cannot tell if COLUMNS=80 they see us export is because we actually measured the terminal width and know it to be 80, or we just punted and used a fallback default", I think, and there is nothing Windows-specific in there, no? In other words, if we use something like the attached as a "less specific band-aid" for now (i.e. direct replacement of your patch to fix the specific 'less' problem), and then later clean it up by actually returning -1 (or -80) from term_columns() as "we do not know" (or "we do not know---use the negation of this value as default"), we can help not just this paticular caller you touched, but all other callers of term_columns(), to make a more intelligent decision in the future if they wanted to. The root of the issue I think is because term_columns() does not give callers to tell if its returned value is merely a guess. pager.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git c/pager.c w/pager.c index 3d37dd7ada..52f27a6765 100644 --- c/pager.c +++ w/pager.c @@ -11,6 +11,10 @@ static struct child_process pager_process = CHILD_PROCESS_INIT; static const char *pager_program; +/* Is the value coming back from term_columns() just a guess? */ +static int term_columns_guessed; + + static void close_pager_fds(void) { /* signal EOF to pager */ @@ -114,7 +118,8 @@ void setup_pager(void) { char buf[64]; xsnprintf(buf, sizeof(buf), "%d", term_columns()); - setenv("COLUMNS", buf, 0); + if (!term_columns_guessed) + setenv("COLUMNS", buf, 0); } setenv("GIT_PAGER_IN_USE", "true", 1); @@ -158,15 +163,20 @@ int term_columns(void) return term_columns_at_startup; term_columns_at_startup = 80; + term_columns_guessed = 1; col_string = getenv("COLUMNS"); - if (col_string && (n_cols = atoi(col_string)) > 0) + if (col_string && (n_cols = atoi(col_string)) > 0) { term_columns_at_startup = n_cols; + term_columns_guessed = 0; + } #ifdef TIOCGWINSZ else { struct winsize ws; - if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col) + if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col) { term_columns_at_startup = ws.ws_col; + term_columns_guessed = 0; + } } #endif