From: Johannes Schindelin <johannes.schindelin@xxxxxx> 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 <johannes.schindelin@xxxxxx> --- 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. Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-982%2Fdscho%2Ffix-duplicated-lines-when-moving-in-pager-v2 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-982/dscho/fix-duplicated-lines-when-moving-in-pager-v2 Pull-Request: https://github.com/gitgitgadget/git/pull/982 Range-diff vs v1: 1: 22d3a9a2c9a2 ! 1: 82099e53bbc9 pager: do not unnecessarily set COLUMNS on Windows @@ Commit message 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`. + determine the correct value for `COLUMNS`, and then set that environment + variable. - However, on Windows it _is_ a problem because Git for Windows' Bash (and - `less.exe`) uses the MSYS2 runtime while `git.exe` does _not_, and - therefore we never get the correct value in Git, but `less.exe` has no - problem obtaining it. + 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). - Let's not override `COLUMNS` in that case. + 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 pager.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/pager.c b/pager.c index 3d37dd7adaa2..b84668eddca2 100644 --- a/pager.c +++ b/pager.c @@ -111,11 +111,13 @@ void setup_pager(void) * to get the terminal size. Let's grab it now, and then set $COLUMNS * to communicate it to any sub-processes. */ +#if !defined(WIN32) || defined(TIOCGWINSZ) { char buf[64]; xsnprintf(buf, sizeof(buf), "%d", term_columns()); setenv("COLUMNS", buf, 0); } +#endif setenv("GIT_PAGER_IN_USE", "true", 1); base-commit: ebf3c04b262aa27fbb97f8a0156c2347fecafafb -- gitgitgadget
