[gdb/tui] Fix spurious newline for long prompt
Commit Message
I noticed that the test-suite doesn't excercise the case in
tui_redisplay_readline that height (initially 1) is changed by this call:
...
tui_puts_internal (w, prompt, &height);
...
I decided to add a test-case, and ran into trouble.
With a prompt of 40 chars, the same size as the terminal width, I expected to
see:
...
16 (gdb) set prompt 123456789A123456789B123
17 456789C123456789>
18 123456789A123456789B123456789C123456789>
19 set prompt (gdb)
20 (gdb)
...
but got instead:
...
16 (gdb) set prompt 123456789A123456789B123
17 456789C123456789>
18 123456789A123456789B123456789C123456789>
19
20 123456789A123456789B123456789C123456789>
21 set prompt (gdb)
22 (gdb)
...
I traced this back to readline's readline_internal_setup, that does:
...
/* If we're not echoing, we still want to at least print a prompt, because
rl_redisplay will not do it for us. If the calling application has a
custom redisplay function, though, let that function handle it. */
if (_rl_echoing_p == 0 && rl_redisplay_function == rl_redisplay)
...
else
{
if (rl_prompt && rl_already_prompted)
rl_on_new_line_with_prompt ();
else
rl_on_new_line ();
(*rl_redisplay_function) ();
...
and then we hit the case that calls rl_on_new_line_with_prompt, which does:
...
/* If the prompt length is a multiple of real_screenwidth, we don't know
whether the cursor is at the end of the last line, or already at the
beginning of the next line. Output a newline just to be safe. */
if (l > 0 && (l % real_screenwidth) == 0)
_rl_output_some_chars ("\n", 1);
...
This doesn't look like a readline bug, because the behaviour matches the
comment.
I looked at ways to work around this, and managed by switching off
rl_already_prompted, which we set to 1 in tui_rl_startup_hook:
...
/* Readline hook to redisplay ourself the gdb prompt.
In the SingleKey mode, the prompt is not printed so that
the command window is cleaner. It will be displayed if
we temporarily leave the SingleKey mode. */
static int
tui_rl_startup_hook (void)
{
rl_already_prompted = 1;
if (tui_current_key_mode != TUI_COMMAND_MODE
&& !gdb_in_secondary_prompt_p (current_ui))
tui_set_key_mode (TUI_SINGLE_KEY_MODE);
tui_redisplay_readline ();
return 0;
}
...
AFAIU, the intent of setting it to 1 has something to do with single-key mode.
I don't think our testsuite excercises single-key mode. I've played around
with single-key mode to see if I could notice a difference in behaviour due
to the change, but didn't observe any.
The call to tui_redisplay_readline looks related to setting rl_already_prompted to
1, so I've removed that one as well.
Tested on x86_64-linux, no regressions.
---
gdb/testsuite/gdb.tui/long-prompt.exp | 115 ++++++++++++++++++++++++++
gdb/tui/tui.c | 2 -
2 files changed, 115 insertions(+), 2 deletions(-)
create mode 100644 gdb/testsuite/gdb.tui/long-prompt.exp
base-commit: 768d1d879be2d134e049521f28d4d5e03b69bafc
new file mode 100644
@@ -0,0 +1,115 @@
+# Copyright 2023 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+# Test a prompt one less than, equal to, and one more than screen width in
+# TUI.
+
+require allow_tui_tests
+
+tuiterm_env
+
+with_test_prefix "prompt size == width + 1" {
+ Term::clean_restart 24 40
+
+ if {![Term::enter_tui]} {
+ unsupported "TUI not supported"
+ return
+ }
+
+ set prompt "123456789A123456789B123456789C123456789D>"
+
+ # Set new prompt, and set old prompt back.
+ send_gdb "set prompt $prompt\n"
+ send_gdb "set prompt (gdb) \n"
+
+ # Expected output:
+ #
+ # 16 (gdb) set prompt 123456789A123456789B123
+ # 17 456789C123456789D>
+ # 18 123456789A123456789B123456789C123456789D
+ # 19 >set prompt (gdb)
+ # 20 (gdb)
+
+ gdb_assert { [Term::wait_for "^>set prompt $gdb_prompt "] } \
+ "got prompt back"
+
+ gdb_assert { $Term::_cur_row == 20 }
+}
+
+with_test_prefix "prompt size == width" {
+ Term::clean_restart 24 40
+
+ if {![Term::enter_tui]} {
+ unsupported "TUI not supported"
+ return
+ }
+
+ set prompt "123456789A123456789B123456789C123456789>"
+
+ # Set new prompt, and set old prompt back.
+ send_gdb "set prompt $prompt\n"
+ send_gdb "set prompt (gdb) \n"
+
+ # Expected output:
+ #
+ # 16 (gdb) set prompt 123456789A123456789B123
+ # 17 456789C123456789>
+ # 18 123456789A123456789B123456789C123456789>
+ # 19 set prompt (gdb)
+ # 20 (gdb)
+ #
+ # Note that we used to get:
+ #
+ # 16 (gdb) set prompt 123456789A123456789B123
+ # 17 456789C123456789>
+ # 18 123456789A123456789B123456789C123456789>
+ # 19
+ # 20 123456789A123456789B123456789C123456789>
+ # 21 set prompt (gdb)
+ # 22 (gdb)
+
+ gdb_assert { [Term::wait_for "^set prompt $gdb_prompt "] } \
+ "got prompt back"
+
+ gdb_assert { $Term::_cur_row == 20 }
+}
+
+with_test_prefix "prompt size == width - 1" {
+ Term::clean_restart 24 40
+
+ if {![Term::enter_tui]} {
+ unsupported "TUI not supported"
+ return
+ }
+
+ set prompt "123456789A123456789B123456789C12345678>"
+
+ # Set new prompt, and set old prompt back.
+ send_gdb "set prompt $prompt\n"
+ send_gdb "set prompt (gdb) \n"
+
+ # Expected output:
+ #
+ # 16 (gdb) set prompt 123456789A123456789B123
+ # 17 456789C12345678>
+ # 18 123456789A123456789B123456789C12345678>s
+ # 19 et prompt (gdb)
+ # 20 (gdb)
+
+ gdb_assert { [Term::wait_for "^et prompt $gdb_prompt "] } \
+ "got prompt back"
+
+ gdb_assert { $Term::_cur_row == 20 }
+}
@@ -264,11 +264,9 @@ tui_rl_next_keymap (int notused1, int notused2)
static int
tui_rl_startup_hook (void)
{
- rl_already_prompted = 1;
if (tui_current_key_mode != TUI_COMMAND_MODE
&& !gdb_in_secondary_prompt_p (current_ui))
tui_set_key_mode (TUI_SINGLE_KEY_MODE);
- tui_redisplay_readline ();
return 0;
}