binutils-gdb/gdb/cli/cli-interp.c
Tom Tromey 817003ed46 Rewrite output redirection and logging
This patch changes how gdb output redirection is done.

Currently, output is done via the UI.  gdb_stdout, for example, is a
define the expands to an lvalue referencing a field in the current UI.
When redirecting, this field may temporarily be reset; and when
logging is enabled or disabled, this is also done.

This has lead to bugs where the combination of redirection and logging
results in use-after-free.  Crashes are readily observable; see the
new test cases.

This patch upends this.  Now, gdb_stdout is simply an rvalue, and
refers to the current interpreter.  The interpreter provides ui_files
that do whatever rewriting is needed (mostly for MI); then output is
forward to the current UI via an indirection (see the new
ui::passthrough_file).

The ui provides paging, logging, timestamps, and the final stream that
writes to an actual file descriptor.

Redirection is handled at the ui layer.  Rather than changing the
output pipeline, new ui_files are simply swapped in by rewriting
pointers, hopefully with a scoped_restore.

Redirecting at the ui layer means that interpreter rewriting is still
applied when capturing output.  This fixes one of the reported bugs.

Not changing the pipeline means that the problems with the combination
of redirect and logging simply vanish.  Logging just changes a flag
and doesn't involve object destruction.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=17697
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28620
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28798
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28948
Approved-By: Andrew Burgess <aburgess@redhat.com>
2026-02-09 08:15:44 -07:00

251 lines
6.3 KiB
C

/* CLI Definitions for GDB, the GNU debugger.
Copyright (C) 2002-2026 Free Software Foundation, Inc.
This file is part of GDB.
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/>. */
#include "cli-interp.h"
#include "exceptions.h"
#include "interps.h"
#include "event-top.h"
#include "ui-out.h"
#include "cli-out.h"
#include "top.h"
#include "ui.h"
#include "infrun.h"
#include "observable.h"
#include "gdbthread.h"
#include "thread-fsm.h"
#include "inferior.h"
cli_interp_base::cli_interp_base (const char *name)
: interp (name)
{}
cli_interp_base::~cli_interp_base ()
{}
/* The console interpreter. */
class cli_interp final : public cli_interp_base
{
public:
explicit cli_interp (const char *name);
~cli_interp () = default;
void resume () override;
void suspend () override;
void exec (const char *command_str) override;
ui_out *interp_ui_out () override;
private:
/* The ui_out for the console interpreter. */
std::unique_ptr<cli_ui_out> m_cli_uiout;
};
cli_interp::cli_interp (const char *name)
: cli_interp_base (name),
m_cli_uiout (new cli_ui_out (m_stdout.get ()))
{
}
/* Suppress notification struct. */
struct cli_suppress_notification cli_suppress_notification;
/* See cli-interp.h.
Breakpoint hits should always be mirrored to a console. Deciding
what to mirror to a console wrt to breakpoints and random stops
gets messy real fast. E.g., say "s" trips on a breakpoint. We'd
clearly want to mirror the event to the console in this case. But
what about more complicated cases like "s&; thread n; s&", and one
of those steps spawning a new thread, and that thread hitting a
breakpoint? It's impossible in general to track whether the thread
had any relation to the commands that had been executed. So we
just simplify and always mirror breakpoints and random events to
all consoles.
OTOH, we should print the source line to the console when stepping
or other similar commands, iff the step was started by that console
(or in MI's case, by a console command), but not if it was started
with MI's -exec-step or similar. */
int
should_print_stop_to_console (struct interp *console_interp,
struct thread_info *tp)
{
if ((bpstat_what (tp->control.stop_bpstat).main_action
== BPSTAT_WHAT_STOP_NOISY)
|| tp->thread_fsm () == nullptr
|| tp->thread_fsm ()->command_interp == console_interp
|| !tp->thread_fsm ()->finished_p ())
return 1;
return 0;
}
/* Observers for several run control events. If the interpreter is
quiet (i.e., another interpreter is being run with
interpreter-exec), print nothing. These are named "cli_base" as
they print to both CLI interpreters and TUI interpreters. */
void
cli_interp_base::on_normal_stop (struct bpstat *bs, int print_frame)
{
if (!print_frame)
return;
/* This event is suppressed. */
if (cli_suppress_notification.normal_stop)
return;
thread_info *thread = inferior_thread ();
if (should_print_stop_to_console (this, thread))
print_stop_event (this->interp_ui_out ());
}
void
cli_interp_base::on_signal_received (enum gdb_signal siggnal)
{
print_signal_received_reason (this->interp_ui_out (), siggnal);
}
void
cli_interp_base::on_signal_exited (gdb_signal sig)
{
print_signal_exited_reason (this->interp_ui_out (), sig);
}
void
cli_interp_base::on_exited (int status)
{
print_exited_reason (this->interp_ui_out (), status);
}
void
cli_interp_base::on_no_history ()
{
print_no_history_reason (this->interp_ui_out ());
}
void
cli_interp_base::on_sync_execution_done ()
{
display_gdb_prompt (NULL);
}
void
cli_interp_base::on_command_error ()
{
display_gdb_prompt (NULL);
}
void
cli_interp_base::on_user_selected_context_changed (user_selected_what selection)
{
/* This event is suppressed. */
if (cli_suppress_notification.user_selected_context)
return;
thread_info *tp = inferior_ptid != null_ptid ? inferior_thread () : nullptr;
if (selection & USER_SELECTED_INFERIOR)
print_selected_inferior (this->interp_ui_out ());
if (tp != nullptr
&& ((selection & (USER_SELECTED_THREAD | USER_SELECTED_FRAME))))
print_selected_thread_frame (this->interp_ui_out (), selection);
}
/* pre_command_loop implementation. */
void
cli_interp_base::pre_command_loop ()
{
display_gdb_prompt (0);
}
void
cli_interp::resume ()
{
struct ui *ui = current_ui;
gdb_setup_readline (1);
ui->input_handler = command_line_handler;
}
void
cli_interp::suspend ()
{
gdb_disable_readline ();
}
void
cli_interp::exec (const char *command_str)
{
/* gdb_stdout could change between the time m_cli_uiout was
initialized and now. Since we're probably using a different
interpreter which has a new ui_file for gdb_stdout, use that one
instead of the default.
It is important that it gets reset every time, since the user
could set gdb to use a different interpreter. */
ui_file *old_stream = m_cli_uiout->set_stream (gdb_stdout);
SCOPE_EXIT { m_cli_uiout->set_stream (old_stream); };
/* Save and override the global ``struct ui_out'' builder. */
scoped_restore saved_uiout = make_scoped_restore (&current_uiout,
m_cli_uiout.get ());
try
{
execute_command (command_str, 1);
}
catch (const gdb_exception_error &ex)
{
exception_print (gdb_stderr, ex);
throw;
}
}
bool
cli_interp_base::supports_command_editing ()
{
return true;
}
ui_out *
cli_interp::interp_ui_out ()
{
return m_cli_uiout.get ();
}
/* Factory for CLI interpreters. */
static struct interp *
cli_interp_factory (const char *name)
{
return new cli_interp (name);
}
/* Standard gdb initialization hook. */
INIT_GDB_FILE (cli_interp)
{
interp_factory_register (INTERP_CONSOLE, cli_interp_factory);
}