The gdb demangler installs a SIGSEGV handler in order to protect gdb
from demangler bugs. However, this is not thread-safe, as signal
handlers are global to the process.
This patch changes gdb to always install a global SIGSEGV handler, and
then lets threads indicate their interest in handling the signal by
setting a thread-local variable.
This patch then arranges for the demangler code to use this; being
sure to arrange for calls to warning and the like to be done on the
main thread.
One thing I wondered while writing this patch is if there are any
systems that do not have "sigaction". If gdb could assume this, it
would simplify this code.
gdb/ChangeLog
2019-11-26 Tom Tromey <tom@tromey.com>
* event-top.h (thread_local_segv_handler): Declare.
* event-top.c (thread_local_segv_handler): New global.
(install_handle_sigsegv, handle_sigsegv): New functions.
(async_init_signals): Install SIGSEGV handler.
* cp-support.c (gdb_demangle_jmp_buf): Change type. Now
thread-local.
(report_failed_demangle): New function.
(gdb_demangle): Make core_dump_allowed atomic. Remove signal
handler-setting code, instead use segv_handler. Run warning code
on main thread.
Change-Id: Ic832bbb033b64744e4b44f14b41db7e4168ce427
This commit applies all changes made after running the gdb/copyright.py
script.
Note that one file was flagged by the script, due to an invalid
copyright header
(gdb/unittests/basic_string_view/element_access/char/empty.cc).
As the file was copied from GCC's libstdc++-v3 testsuite, this commit
leaves this file untouched for the time being; a patch to fix the header
was sent to gcc-patches first.
gdb/ChangeLog:
Update copyright year range in all GDB files.
This changes ui::input_handler to take a unique_xmalloc_ptr. This
clarifies the ownership transfer of input_handler's argument.
gdb/ChangeLog
2018-12-30 Tom Tromey <tom@tromey.com>
* event-top.h (command_line_handler): Update.
* top.c (class gdb_readline_wrapper_cleanup) <m_handler_orig>:
Update.
(gdb_readline_wrapper_line): Update.
* top.h (struct ui) <input_handler>: Take a unique_xmalloc_ptr.
(handle_line_of_input): Update.
* event-top.c: Update.
(gdb_readline_no_editing_callback): Update.
(command_line_handler): Take a unique_xmalloc_ptr.
(handle_line_of_input): Take a const char *.
(command_line_append_input_line): Take a const char *.
The STOP_SIGNAL macro was originally added for Convex Unix
(https://en.wikipedia.org/wiki/Convex_Computer).
In:
git show 7a67dd45ca1c:gdb/m-convex.h
we see:
~~~
/* Use SIGCONT rather than SIGTSTP because convex Unix occasionally
turkeys SIGTSTP. I think. */
#define STOP_SIGNAL SIGCONT
~~~
That's gdb-3.5, 1990... In gdb/ChangeLog-3.x we see:
~~~
Tue Apr 18 13:43:37 1989 Randall Smith (randy at apple-gunkies.ai.mit.edu)
Various changes involved in 1) getting gdb to work on the convex,
[...]
Made whatever signal indicates a stop configurable (via macro
STOP_SIGNAL).
(main): Setup use of above as a signal handler. Added check for
"-nw" in args already processed.
(command_line_input): SIGTSTP ==>STOP_SIGNAL.
~~~
Support for Convex Unix is long gone, and nothing else overrides
STOP_SIGNAL. So just use SIGTSTP directly, removing a little
obfuscation.
(I don't really understand why we override [1] readline's SIGTSTP
handler (only) when reading scripts (and then fail to restore it
properly, assuming SIG_DFL...), but I'll leave that for another pass.
[1] - Actually, starting with readline 6.3, readline is no longer
installing its handlers while GDB is in control...)
gdb/ChangeLog:
2017-11-06 Pedro Alves <palves@redhat.com>
* event-top.c: Check SIGTSTP instead of STOP_SIGNAL thoughout.
(async_init_signals): Adjust.
(handle_stop_sig): Rename to ...
(handle_sigtstp): ... this.
(async_stop_sig): Rename to ...
(async_sigtstp_handler): ... this, and delete STOP_SIGNAL !=
SIGTSTP path.
* event-top.h: Move signal.h include to the top. Check SIGTSTP
instead of STOP_SIGNAL thoughout.
(handle_stop_sig): Rename to ...
(handle_sigtstp): ... this.
* top.c (command_line_input): Replace STOP_SIGNAL -> SIGTSTP.
This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
Due to the way that readline's API works (based on globals), we can
only have one instance of readline in a process. So the goal of this
patch is to only allow editing in the main UI, and make sure that only
one UI calls into readline. Some MI paths touch readline variables
currently, which is bad as that is changing variables that matter for
the main console UI. This patch fixes those.
This actually fixes a nasty bug -- starting gdb in MI mode ("gdb
-i=mi"), and then doing "set editing on" crashes GDB, because MI is
not prepared to use readline:
set editing on
&"set editing on\n"
=cmd-param-changed,param="editing",value="on"
^done
(gdb)
p 1
readline: readline_callback_read_char() called with no handler!
Aborted (core dumped)
The fix for that was to add an interp_proc method to query the
interpreter whether it actually supports editing. New test included.
gdb/ChangeLog:
2016-06-21 Pedro Alves <palves@redhat.com>
PR mi/20034
* cli/cli-interp.c: Include cli-interp.h and event-top.h.
(cli_interpreter_resume): Pass 1 to gdb_setup_readline. Set the
UI's input_handler here.
(cli_interpreter_supports_command_editing): New function.
(cli_interp_procs): Install it.
* cli/cli-interp.h: New file.
* event-top.c (async_command_editing_p): Rename to ...
(set_editing_cmd_var): ... this.
(change_line_handler): Add parameter 'editing', and use it. Bail
early if the interpreter doesn't support editing. Don't touch
readline state if editing is off.
(gdb_rl_callback_handler_remove, gdb_rl_callback_handler_install)
(gdb_rl_callback_handler_reinstall): Assert the current UI is the
main UI.
(display_gdb_prompt): Don't call gdb_rl_callback_handler_remove if
not using readline. Check whether the current UI is using command
editing instead of checking the async_command_editing_p global.
(set_async_editing_command): Delete.
(gdb_setup_readline): Add 'editing' parameter. Only allow editing
on the main UI. Don't touch readline state if editing is off.
(gdb_disable_readline): Don't touch readline state if editing is
off.
* event-top.h (gdb_setup_readline): Add 'int' parameter.
(set_async_editing_command): Delete declaration.
(change_line_handler, command_line_handler): Declare.
(async_command_editing_p): Rename to ...
(set_editing_cmd_var): ... this.
* infrun.c (reinstall_readline_callback_handler_cleanup): Check
whether the current UI has editing enabled rather than checking
the async_command_editing_p global.
* interps.c (interp_supports_command_editing): New function.
* interps.h (interp_supports_command_editing_ftype): New typedef.
(struct interp_procs) <supports_command_editing_proc>: New field.
(interp_supports_command_editing): Declare.
* mi/mi-interp.c (mi_interpreter_resume): Pass 0 to
gdb_setup_readline. Don't clear the async_command_editing_p
global. Update comments.
* top.c (gdb_readline_wrapper_line, gdb_readline_wrapper): Check
whether the current UI has editing enabled rather than checking
the async_command_editing_p global. Don't touch readline state if
editing is off.
(undo_terminal_modifications_before_exit): Switch to the main UI.
Unconditionally call gdb_disable_readline.
(set_editing): New function.
(show_async_command_editing_p): Rename to ...
(show_editing): ... this. Show the state of the current UI.
(_initialize_top): Adjust.
* top.h (struct ui) <command_editing>: New field.
* tui/tui-interp.c: Include cli/cli-interp.h.
(tui_resume): Pass 1 to gdb_setup_readline. Set the UI's
input_handler.
(tui_interp_procs): Install
cli_interpreter_supports_command_editing.
* tui/tui-io.c (tui_getc): Check whether the current UI has
editing enabled rather than checking the async_command_editing_p
global.
gdb/testsuite/ChangeLog:
2016-06-21 Pedro Alves <palves@redhat.com>
PR mi/20034
* gdb.mi/mi-editing.exp: New file.
And with that, we can switch the current UI to the UI whose input
descriptor woke up the event loop. IOW, if the user types in UI 2,
the event loop wakes up, switches to UI 2, and processes the input.
Next the user types in UI 3, the event loop wakes up and switches to
UI 3, etc.
gdb/ChangeLog:
2016-06-21 Pedro Alves <palves@redhat.com>
* event-top.c (input_fd): Delete.
(stdin_event_handler): Switch to the UI whose input descriptor got
the event. Adjust to per-UI input_fd.
(gdb_setup_readline): Don't set the input_fd global. Adjust to
per-UI input_fd.
(gdb_disable_readline): Adjust to per-UI input_fd.
* event-top.h (input_fd): Delete declaration.
* linux-nat.c (linux_nat_terminal_inferior): Don't remove input_fd
from the event-loop here.
(linux_nat_terminal_ours): Don't register input_fd in the
event-loop here.
* main.c (captured_main): Adjust to per-UI input_fd.
* remote.c (remote_terminal_inferior): Don't remove input_fd from
the event-loop here.
(remote_terminal_ours): Don't register input_fd in the event-loop
here.
* target.c: Include top.h and event-top.h.
(target_terminal_inferior): Remove input_fd from the event-loop
here.
(target_terminal_ours): Register input_fd in the event-loop.
* top.h (struct ui) <input_fd>: New field.
This is a step towards supporting multiple consoles/MIs, each on its
own stdio streams / terminal.
See intro comment in top.h.
(I've had trouble picking a name for this object. I've started out
with "struct console" originally. But then this is about MI as well,
and there's "interpreter-exec console", which is specifically about
the CLI...
So I changed to "struct terminal", but, then we have a terminal object
that works when the input is not a terminal as well ...
Then I sort of gave up and renamed it to "struct top_level". But it
then gets horribly confusing when we talk about the "top level
interpreter that's running on the current top level".
In the end, I realized we're already sort of calling this "ui", in
struct ui_out, struct ui_file, and a few coments here and there.)
gdb/ChangeLog:
2016-06-21 Pedro Alves <palves@redhat.com>
* event-top.c: Update readline-related comments.
(input_handler, call_readline): Delete globals.
(gdb_rl_callback_handler): Call the current UI's input_handler
method.
(change_line_handler): Adjust to set current UI's properties
instead of globals.
(current_ui_, current_ui): New globals.
(get_command_line_buffer): Rewrite to refer to the current UI.
(stdin_event_handler): Adjust to call the call_readline method of
the current UI.
(gdb_readline_no_editing_callback): Adjust to call the current UI's
input_handler method.
(gdb_setup_readline): Adjust to set current UI's properties
instead of globals.
* event-top.h (call_readline, input_handler): Delete declarations.
* mi/mi-interp.c (mi_interpreter_resume): Adjust to set current
UI's properties instead of globals.
* top.c (gdb_readline_wrapper_cleanup): Adjust to set current UI's
properties instead of globals.
(gdb_readline_wrapper): Adjust to call and set current UI's
methods instead of globals.
* top.h: Include buffer.h and event-loop.h.
(struct ui): New struct.
(current_ui): New declaration.
I didn't manage to usefully split this further into smaller
independent pieces, so:
- Use "struct buffer" more.
- Split out the responsibility of composing a complete command line
from multiple input lines split with backslash
(
E.g.:
(gdb) print \
1 + \
2
$1 = 3
(gdb)
)
to a separate function. Note we don't need the separate
readline_input_state and more_to_come globals at all. They were
just obfuscating the logic.
- Factor out the tricky mostly duplicated code in
command_line_handler and command_line_input.
gdb/ChangeLog
2016-03-09 Pedro Alves <palves@redhat.com>
* event-top.c (more_to_come): Delete.
(struct readline_input_state): Delete.
(readline_input_state): Delete.
(get_command_line_buffer): New function.
(command_handler): Update comments. Don't handle NULL commands
here. Do not execute commented lines.
(command_line_append_input_line): New function.
(handle_line_of_input): New function, partly based on
command_line_handler and command_line_input.
(command_line_handler): Rewrite.
* event-top.h (command_handler): New declaration.
(command_loop): Defer command execution to command_handler.
(command_line_input): Update comments. Simplify, using struct
buffer and handle_line_of_input.
* top.h (struct buffer): New forward declaration.
(handle_line_of_input): New declaration.
The comments and existence of this global are a bit of misleading
obfuscation, since this is only ever used to print the prompt
annotation, and never changes. Just hardcode "prompt" where
necessary, as done for most other annotations.
gdb/ChangeLog:
2016-03-09 Pedro Alves <palves@redhat.com>
* event-top.c (async_annotation_suffix): Delete.
(top_level_prompt, command_line_handler): Don't use
'async_annotation_suffix' and simplify.
* event-top.h (async_annotation_suffix): Delete declaration.
(init_main): Remove reference to 'async_annotation_suffix'.
The type of the function pointer PyOS_ReadlineFunctionPointer (part of the
Python C API), which we use, slightly changed starting with Python 3.4. The
signature went from
PyAPI_DATA(char) *(*PyOS_ReadlineFunctionPointer)(FILE *, FILE *, char *);
to
PyAPI_DATA(char) *(*PyOS_ReadlineFunctionPointer)(FILE *, FILE *, const char *);
The parameter that changed is the prompt text.
This commits adjust gdb accordingly by making the prompt_arg parameter
const, as well as the fallouts of that. I needed to rework how
annotations are added to the prompt, since the it is now const. If
annotations are enabled, it will make a copy of the prompt overwrite the
prompt variable that is used throughout the function. Otherwise, no copy
is done and the original prompt_arg value is passed.
I changed the signature of deprecated_readline_hook. I would've changed any
user of it, but it seems like nothing is using it,
Built-tested with python 2.7.x, 3.3.y and 3.4.z.
gdb/ChangeLog:
* defs.h (gdb_readline): Constify argument.
(gdb_readline_wrapper): Same.
(command_line_input): Same.
(deprecated_readline_hook): Same.
* top.c (deprecated_readline_hook): Same.
(gdb_readline): Same.
(gdb_readline_wrapper): Same.
(command_line_input): Constify argument. Pass prompt to
called functions instead of local_prompt, overwriting prompt
if using annotations.
* event-top.h (display_gdb_prompt): Constify argument.
* event-top.c (display_gdb_prompt): Same.
* python/py-gdb-readline.c (gdbpy_readline_wrapper): Constify
argument if building with Python 3.4 and up.
Signed-off-by: Simon Marchi <simon.marchi@ericsson.com>
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.
Joel Brobecker
Tom Tromey
Christian Biesinger
Pedro Alves
Simon Marchi
Patrick Palka
Andrew Burgess
Joel Brobecker
Yao Qi
Phil Muldoon
Michael Snyder
Vladimir Prus
Daniel Jacobowitz
Eli Zaretskii
Andrew Stubbs
Andrew Cagney
Tom Tromey
Mark Kettenis
Jason Molenda