From 1c58c8e9bf9fdf593593fb404e06db506685475d Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Wed, 12 Apr 2023 14:44:42 +0200 Subject: [PATCH 8/8] [gdb/tui] Fix TUI for TERM=ansi With TERM=ansi, when resizing a TUI window from LINES/COLUMNS 31/118 (maximized) to 20/78 (de-maximized), I get a garbled screen and a message: ... @@ resize done 0, size = 77x20 ... with the resulting width being 77 instead of the expected 78. [ The discrepancy also manifests in CLI, filed as PR30346. ] The discrepancy comes from tui_resize_all, where we ask readline for the screen size: ... rl_get_screen_size (&screenheight, &screenwidth); ... As it happens, when TERM is set to ansi, readline decides that the terminal cannot auto-wrap lines, and reserves one column to deal with that, and as a result reports back one less than the actual screen width: ... $ echo $COLUMNS 78 $ TERM=xterm gdb -ex "show width" -ex q Number of characters gdb thinks are in a line is 78. $ TERM=ansi gdb -ex "show width" -ex q Number of characters gdb thinks are in a line is 77. ... In tui_resize_all, we need the actual screen width, and using a screenwidth of one less than the actual value garbles the screen. This is currently not causing trouble in testing because we have a workaround in place in proc Term::resize. Fix this by: - detecting when readline will report back less than the actual screen width, - accordingly setting a new variable readline_hidden_cols, - using readline_hidden_cols in tui_resize_all to fix the resize problem, and - removing the workaround in Term::resize. The test-case gdb.tui/empty.exp serves as regression test. Tested on x86_64-linux. PR tui/30337 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30337 --- gdb/testsuite/lib/tuiterm.exp | 10 ++-------- gdb/tui/tui-win.c | 3 +++ gdb/utils.c | 22 ++++++++++++++++++++++ gdb/utils.h | 7 +++++++ 4 files changed, 34 insertions(+), 8 deletions(-) diff --git a/gdb/testsuite/lib/tuiterm.exp b/gdb/testsuite/lib/tuiterm.exp index d8a99d2798a..f59a66a0958 100644 --- a/gdb/testsuite/lib/tuiterm.exp +++ b/gdb/testsuite/lib/tuiterm.exp @@ -1122,16 +1122,10 @@ namespace eval Term { # explicit here. This also simplifies waiting for the redraw. _do_resize $rows $_cols stty rows $_rows < $::gdb_tty_name - # Due to the strange column resizing behavior, and because we - # don't care about this intermediate resize, we don't check - # the size and the "@@ " prefix here. - wait_for "resize done $_resize_count" + wait_for "@@ resize done $_resize_count, size = ${_cols}x${rows}" incr _resize_count - # Somehow the number of columns transmitted to gdb is one less - # than what we request from expect. We hide this weird - # details from the caller. _do_resize $_rows $cols - stty columns [expr {$_cols + 1}] < $::gdb_tty_name + stty columns $_cols < $::gdb_tty_name wait_for "@@ resize done $_resize_count, size = ${_cols}x${rows}" incr _resize_count } diff --git a/gdb/tui/tui-win.c b/gdb/tui/tui-win.c index 3b17cb8dd29..7186fb97d68 100644 --- a/gdb/tui/tui-win.c +++ b/gdb/tui/tui-win.c @@ -36,6 +36,7 @@ #include "gdbsupport/event-loop.h" #include "gdbcmd.h" #include "async-event.h" +#include "utils.h" #include "tui/tui.h" #include "tui/tui-io.h" @@ -528,6 +529,8 @@ tui_resize_all (void) int screenheight, screenwidth; rl_get_screen_size (&screenheight, &screenwidth); + screenwidth += readline_hidden_cols; + width_diff = screenwidth - tui_term_width (); height_diff = screenheight - tui_term_height (); if (height_diff || width_diff) diff --git a/gdb/utils.c b/gdb/utils.c index 6ec1cc0d48d..82138a1fc2c 100644 --- a/gdb/utils.c +++ b/gdb/utils.c @@ -1116,6 +1116,10 @@ static bool filter_initialized = false; +/* See utils.h. */ + +int readline_hidden_cols = 0; + /* Initialize the number of lines per page and chars per line. */ void @@ -1144,6 +1148,24 @@ init_page_info (void) /* Get the screen size from Readline. */ rl_get_screen_size (&rows, &cols); + + /* Readline: + - ignores the COLUMNS variable when detecting screen width + (because rl_prefer_env_winsize defaults to 0) + - puts the detected screen width in the COLUMNS variable + (because rl_change_environment defaults to 1) + - may report one less than the detected screen width in + rl_get_screen_size (when _rl_term_autowrap == 0). + Set readline_hidden_cols by comparing COLUMNS to cols as returned by + rl_get_screen_size. */ + char *columns_env = getenv ("COLUMNS"); + gdb_assert (columns_env != nullptr); + int columns_env_val = atoi (columns_env); + gdb_assert (columns_env_val != 0); + readline_hidden_cols = columns_env_val - cols; + gdb_assert (readline_hidden_cols >= 0); + gdb_assert (readline_hidden_cols <= 1); + lines_per_page = rows; chars_per_line = cols; diff --git a/gdb/utils.h b/gdb/utils.h index a383036bcfe..29ff376bb52 100644 --- a/gdb/utils.h +++ b/gdb/utils.h @@ -335,4 +335,11 @@ extern void copy_bitwise (gdb_byte *dest, ULONGEST dest_offset, const gdb_byte *source, ULONGEST source_offset, ULONGEST nbits, int bits_big_endian); +/* When readline decides that the terminal cannot auto-wrap lines, it reduces + the width of the reported screen width by 1. This variable indicates + whether that's the case or not, allowing us to add it back where + necessary. See _rl_term_autowrap in readline/terminal.c. */ + +extern int readline_hidden_cols; + #endif /* UTILS_H */ -- 2.35.3