This patch fixes the annoying bug where key sequences such as Alt_F or
Alt_B (go forward or backwards by a word) do not behave promptly in TUI.
You have to press a third key in order for the key sequence to register.
This is mostly ncurses' fault. Calling wgetch() normally causes ncurses
to read only a single key from stdin. However if the key read is the
start-sequence key (^[ a.k.a. ESC) then wgetch() reads TWO keys from
stdin, storing the 2nd key into an internal FIFO buffer and returning
the start-sequence key. The extraneous read of the 2nd key makes us
miss its corresponding stdin event, so the event loop blocks until a
third key is pressed. This explains why such key sequences do not
behave promptly in TUI.
To fix this issue, we must somehow compensate for the missed stdin event
corresponding to the 2nd byte of a key sequence. This patch achieves
this by hacking up the stdin event handler to conditionally execute the
readline callback multiple times in a row. This is done via a new
global variable, call_stdin_event_handler_again_p, which is set from
tui_getc() when we receive a start-sequence key and notice extra pending
input in the ncurses buffer.
Tested on x86_64-unknown-linux-gnu.
gdb/ChangeLog:
* event-top.h (call_stdin_event_handler_again_p): Declare.
* event-top.c (call_stdin_event_handler_again_p): Define.
(stdin_event_handler): Use it.
* tui/tui-io.c (tui_getc): Prepare to call the stdin event
handler again if there is pending input following a
start sequence.
This is more of a readline/terminal issue than a Python one.
PR17372 is a regression in 7.8 caused by the fix for PR17072:
commit 0017922d02
Author: Pedro Alves <palves@redhat.com>
Date: Mon Jul 14 19:55:32 2014 +0100
Background execution + pagination aborts readline/gdb
gdb_readline_wrapper_line removes the handler after a line is
processed. Usually, we'll end up re-displaying the prompt, and that
reinstalls the handler. But if the output is coming out of handling
a stop event, we don't re-display the prompt, and nothing restores the
handler. So the next input wakes up the event loop and calls into
readline, which aborts.
...
gdb/
2014-07-14 Pedro Alves <palves@redhat.com>
PR gdb/17072
* top.c (gdb_readline_wrapper_line): Tweak comment.
(gdb_readline_wrapper_cleanup): If readline is enabled, reinstall
the input handler callback.
The problem is that installing the input handler callback also preps
the terminal, putting it in raw mode and with echo disabled, which is
bad if we're going to call a command that assumes cooked/canonical
mode, and echo enabled, like in the case of the PR, Python's
interactive shell. Another example I came up with that doesn't depend
on Python is starting a subshell with "(gdb) shell /bin/sh" from a
multi-line command. Tests covering both these examples are added.
The fix is to revert the original fix for PR gdb/17072, and instead
restore the callback handler after processing an asynchronous target
event.
Furthermore, calling rl_callback_handler_install when we already have
some input in readline's line buffer discards that input, which is
obviously a bad thing to do while the user is typing. No specific
test is added for that, because I first tried calling it even if the
callback handler was still installed and that resulted in hundreds of
failures in the testsuite.
gdb/
2014-10-29 Pedro Alves <palves@redhat.com>
PR python/17372
* event-top.c (change_line_handler): Call
gdb_rl_callback_handler_remove instead of
rl_callback_handler_remove.
(callback_handler_installed): New global.
(gdb_rl_callback_handler_remove, gdb_rl_callback_handler_install)
(gdb_rl_callback_handler_reinstall): New functions.
(display_gdb_prompt): Call gdb_rl_callback_handler_remove and
gdb_rl_callback_handler_install instead of
rl_callback_handler_remove and rl_callback_handler_install.
(gdb_disable_readline): Call gdb_rl_callback_handler_remove
instead of rl_callback_handler_remove.
* event-top.h (gdb_rl_callback_handler_remove)
(gdb_rl_callback_handler_install)
(gdb_rl_callback_handler_reinstall): New declarations.
* infrun.c (reinstall_readline_callback_handler_cleanup): New
cleanup function.
(fetch_inferior_event): Install it.
* top.c (gdb_readline_wrapper_line) Call
gdb_rl_callback_handler_remove instead of
rl_callback_handler_remove.
(gdb_readline_wrapper_cleanup): Don't call
rl_callback_handler_install.
gdb/testsuite/
2014-10-29 Pedro Alves <palves@redhat.com>
PR python/17372
* gdb.python/python.exp: Test a multi-line command that spawns
interactive Python.
* gdb.base/multi-line-starts-subshell.exp: New file.
https://sourceware.org/ml/gdb-patches/2013-09/msg00179.html
gdb/ChangeLog
* cli/cli-interp.c (_initialize_cli_interp): Add a
command_loop_proc to interp_procs.
* event-top.c (cli_command_loop): Change signature to match
interp_command_loop_ftype.
* event-top.h (cli_command_loop): Same.
* interps.c (interp_new): Require every interpreter to have a
command_loop_proc.
(current_interp_command_loop): Just call the command_loop_proc on
the current interpreter.
* tui/tui-interp.c (_initialize_tui_interp): Add a
command_loop_proc to interp_procs.
Two modifications:
1. The addition of 2013 to the copyright year range for every file;
2. The use of a single year range, instead of potentially multiple
year ranges, as approved by the FSF.
* event-top.h (MAXPROMPTS, struct prompts): Delete.
(set_async_annotation_level, set_async_prompt, pop_prompt)
(push_prompt, new_async_prompt): Delete declarations.
* top.h (get_prompt, set_prompt): Change prototype.
(get_prefix, set_prefix, get_suffix, set_suffix): Delete
declarations.
* top.c (command_loop):
(top_prompt): New global.
(get_prefix, set_prefix, get_suffix, ): Delete.
(get_prompt, set_prompt): Rewrite.
(show_new_async_prompt): Rename to ...
(show_prompt): ... this.
(init_main): Adjust. Don't handle --annotate=2 here.
* event-top.c (new_async_prompt): Delete.
(the_prompts): Delete.
(more_to_come): Make static.
(display_gdb_prompt): Use top_level_prompt() to compute the top
level prompt, and don't notify the before_prompt observers
directly here. Always trick readline into not trying to display
the prompt if sync_execution and displaying the primary prompt.
If displaying a local/secondary prompt, always show it, even if
sync_execution is set.
(change_annotation_level): Delete.
(top_level_prompt): New, based on change_annotation_level.
(push_prompt, pop_prompt): Delete.
(async_disable_stdin): No longer pushes prompt.
(command_line_handler): No longer pushes or pops prompt. If more
input is expected, call display_gdb_prompt with an explicit empty
prompt.
(async_stop_sig): Adjust.
(set_async_annotation_level, set_async_prompt): Delete.
* python/python.c (before_prompt_hook): Adjust.
* event-top.c (cli_command_loop): Use get_prompt, get_suffix,
get_prefix.
(display_gdb_prompt): Likewise.
(change_annotation_level): Likewise.
(push_prompt): Likewise.
(pop_prompt): Likewise.
(handle_stop_sig): Use get_prompt with a level.
* top.c (command_loop): Use get_prompt with a level.
(set_async_annotation_level): Use set_prompt with a level.
(get_prefix): New function.
(set_prefix): Ditto.
(set_suffix): Ditto.
(get_suffix): Ditto.
(get_prompt): Accept a level argument.
(set_prompt): Accept a level argument. Free old prompts. Set
new_async_prompt if level is 0.
(init_main): Use set_prompt with a level. Do not set
new_async_prompt.
* event-top.h (PROMPT, SUFFIX, PREFIX): Move to top.c
* top.h: Declare set_suffix, get_suffix, set_prefix, get_prefix.
Modify set_prompt, get_prompt to account for levels.
* tui/tui-interp.c (tui_command_loop): Use get_prompt with a
level
* python/python.c (before_prompt_hook): Use set_prompt.
