From: Johannes Schindelin <johannes.schindelin@xxxxxx> We query `TIOCGWINSZ` in Git to determine the correct value for `COLUMNS`, and then set that environment variable. If `TIOCGWINSZ` is not available, we fall back to the hard-coded value 80 _and still_ set the environment variable. On Windows this 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). Since https://github.com/gwsw/less/commit/bb0ee4e76c2, `less` prefers the `COLUMNS` variable over asking ncurses itself. 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. Let's just not set `COLUMNS` unless we managed to query the actual value from the terminal. This fixes https://github.com/git-for-windows/git/issues/3235 Co-authored-by: Junio C Hamano <gitster@xxxxxxxxx> 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 v2: * We no longer avoid setting COLUMNS based on the Operating Systems and the presence of TIOCGWINSZ, but set a flag specifically when we successfully queried the terminal's dimensions, and otherwise skip the setenv(COLUMNS) call. 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-v3 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-982/dscho/fix-duplicated-lines-when-moving-in-pager-v3 Pull-Request: https://github.com/gitgitgadget/git/pull/982 Range-diff vs v2: 1: 82099e53bbc9 ! 1: fe2ee68de43e pager: do not unnecessarily set COLUMNS on Windows @@ Metadata Author: Johannes Schindelin <Johannes.Schindelin@xxxxxx> ## Commit message ## - pager: do not unnecessarily set COLUMNS on Windows + pager: avoid setting COLUMNS when we're guessing its value - Since https://github.com/gwsw/less/commit/bb0ee4e76c2, `less` prefers - the `COLUMNS` variable over asking ncurses itself. + We query `TIOCGWINSZ` in Git to determine the correct value for + `COLUMNS`, and then set that environment variable. - 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. + If `TIOCGWINSZ` is not available, we fall back to the hard-coded value + 80 _and still_ set the environment variable. - However, on Windows it _is_ a problem. The reason is that Git for + On Windows this 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). + Since https://github.com/gwsw/less/commit/bb0ee4e76c2, `less` prefers + the `COLUMNS` variable over asking ncurses itself. 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 @@ Commit message 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. + Let's just not set `COLUMNS` unless we managed to query the actual value + from the terminal. This fixes https://github.com/git-for-windows/git/issues/3235 + Co-authored-by: Junio C Hamano <gitster@xxxxxxxxx> Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx> ## pager.c ## +@@ + 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 */ @@ pager.c: 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); +- setenv("COLUMNS", buf, 0); ++ if (!term_columns_guessed) ++ setenv("COLUMNS", buf, 0); } -+#endif setenv("GIT_PAGER_IN_USE", "true", 1); +@@ pager.c: 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 pager.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/pager.c b/pager.c index 3d37dd7adaa2..52f27a6765c8 100644 --- a/pager.c +++ b/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 base-commit: ebf3c04b262aa27fbb97f8a0156c2347fecafafb -- gitgitgadget
