binutils-gdb/gdb/tui/tui-data.h
Andrew Burgess 29db1eb339 gdb: return true in TuiWindow.is_valid only if TUI is enabled
If the user implements a TUI window in Python, and this window
responds to GDB events and then redraws its window contents then there
is currently an edge case which can lead to problems.

The Python API documentation suggests that calling methods like erase
or write on a TUI window (from Python code) will raise an exception if
the window is not valid.

And the description for is_valid says:

  This method returns True when this window is valid. When the user
  changes the TUI layout, windows no longer visible in the new layout
  will be destroyed. At this point, the gdb.TuiWindow will no longer
  be valid, and methods (and attributes) other than is_valid will
  throw an exception.

From this I, as a user, would expect that if I did 'tui disable' to
switch back to CLI mode, then the window would no longer be valid.
However, this is not the case.

When the TUI is disabled the windows in the TUI are not deleted, they
are simply hidden.  As such, currently, the is_valid method continues
to return true.

This means that if the users Python code does something like:

  def event_handler (e):
    global tui_window_object
    if tui_window_object->is_valid ():
      tui_window_object->erase ()
      tui_window_object->write ("Hello World")
  gdb.events.stop.connect (event_handler)

Then when a stop event arrives GDB will try to draw the TUI window,
even when the TUI is disabled.

This exposes two bugs.  First, is_valid should be returning false in
this case, second, if the user forgot to add the is_valid call, then I
believe the erase and write calls should be throwing an
exception (when the TUI is disabled).

The solution to both of these issues is I think bound together, as it
depends on having a working 'is_valid' check.

There's a rogue assert added into tui-layout.c as part of this
commit.  While working on this commit I managed to break GDB such that
TUI_CMD_WIN was nullptr, this was causing GDB to abort.  I'm leaving
the assert in as it might help people catch issues in the future.

This patch is inspired by the work done here:

  https://sourceware.org/pipermail/gdb-patches/2020-December/174338.html

gdb/ChangeLog:

	* python/py-tui.c (gdbpy_tui_window) <is_valid>: New member
	function.
	(REQUIRE_WINDOW): Call is_valid member function.
	(REQUIRE_WINDOW_FOR_SETTER): New define.
	(gdbpy_tui_is_valid): Call is_valid member function.
	(gdbpy_tui_set_title): Call REQUIRE_WINDOW_FOR_SETTER instead.
	* tui/tui-data.h (struct tui_win_info) <is_visible>: Check
	tui_active too.
	* tui/tui-layout.c (tui_apply_current_layout): Add an assert.
	* tui/tui.c (tui_enable): Move setting of tui_active earlier in
	the function.

gdb/doc/ChangeLog:

	* python.texinfo (TUI Windows In Python): Extend description of
	TuiWindow.is_valid.

gdb/testsuite/ChangeLog:

	* gdb.python/tui-window-disabled.c: New file.
	* gdb.python/tui-window-disabled.exp: New file.
	* gdb.python/tui-window-disabled.py: New file.
2021-02-08 11:56:16 +00:00

211 lines
5.6 KiB
C++

/* TUI data manipulation routines.
Copyright (C) 1998-2021 Free Software Foundation, Inc.
Contributed by Hewlett-Packard Company.
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/>. */
#ifndef TUI_TUI_DATA_H
#define TUI_TUI_DATA_H
#include "tui/tui.h"
#include "gdb_curses.h" /* For WINDOW. */
#include "observable.h"
/* A deleter that calls delwin. */
struct curses_deleter
{
void operator() (WINDOW *win) const
{
delwin (win);
}
};
#define MIN_WIN_HEIGHT 3
/* Generic window information. */
struct tui_win_info
{
protected:
tui_win_info () = default;
DISABLE_COPY_AND_ASSIGN (tui_win_info);
/* This is called after the window is resized, and should update the
window's contents. */
virtual void rerender ();
virtual void make_window ();
public:
tui_win_info (tui_win_info &&) = default;
virtual ~tui_win_info () = default;
/* Call to refresh this window. */
virtual void refresh_window ();
/* Make this window visible or invisible. */
virtual void make_visible (bool visible);
/* Return the name of this type of window. */
virtual const char *name () const = 0;
/* Compute the maximum height of this window. */
virtual int max_height () const;
/* Compute the minimum height of this window. */
virtual int min_height () const
{
return MIN_WIN_HEIGHT;
}
/* Compute the maximum width of this window. */
int max_width () const;
/* Compute the minimum width of this window. */
int min_width () const
{
return 3;
}
/* Return true if this window can be boxed. */
virtual bool can_box () const
{
return true;
}
/* Resize this window. The parameters are used to set the window's
size and position. */
virtual void resize (int height, int width,
int origin_x, int origin_y);
/* Return true if this window is visible. */
bool is_visible () const
{
return handle != nullptr && tui_active;
}
/* Return true if this window can accept the focus. */
virtual bool can_focus () const
{
return true;
}
/* Disable output until the next call to doupdate. */
void no_refresh ()
{
if (handle != nullptr)
wnoutrefresh (handle.get ());
}
/* Called after the tab width has been changed. */
virtual void update_tab_width ()
{
}
/* Set whether this window is highlighted. */
void set_highlight (bool highlight)
{
is_highlighted = highlight;
}
/* Methods to scroll the contents of this window. Note that they
are named with "_scroll" coming at the end because the more
obvious "scroll_forward" is defined as a macro in term.h. */
void forward_scroll (int num_to_scroll);
void backward_scroll (int num_to_scroll);
void left_scroll (int num_to_scroll);
void right_scroll (int num_to_scroll);
/* Return true if this window can be scrolled, false otherwise. */
virtual bool can_scroll () const
{
return true;
}
void check_and_display_highlight_if_needed ();
/* Window handle. */
std::unique_ptr<WINDOW, curses_deleter> handle;
/* Window width. */
int width = 0;
/* Window height. */
int height = 0;
/* Origin of window. */
int x = 0;
int y = 0;
/* Window title to display. */
std::string title;
/* Is this window highlighted? */
bool is_highlighted = false;
protected:
/* Scroll the contents vertically. This is only called via
forward_scroll and backward_scroll. */
virtual void do_scroll_vertical (int num_to_scroll) = 0;
/* Scroll the contents horizontally. This is only called via
left_scroll and right_scroll. */
virtual void do_scroll_horizontal (int num_to_scroll) = 0;
};
/* Constant definitions. */
#define SRC_NAME "src"
#define CMD_NAME "cmd"
#define DATA_NAME "regs"
#define DISASSEM_NAME "asm"
#define STATUS_NAME "status"
/* Global Data. */
extern struct tui_win_info *tui_win_list[MAX_MAJOR_WINDOWS];
#define TUI_SRC_WIN ((tui_source_window *) tui_win_list[SRC_WIN])
#define TUI_DISASM_WIN ((tui_disasm_window *) tui_win_list[DISASSEM_WIN])
#define TUI_DATA_WIN ((tui_data_window *) tui_win_list[DATA_WIN])
#define TUI_CMD_WIN ((tui_cmd_window *) tui_win_list[CMD_WIN])
#define TUI_STATUS_WIN ((tui_locator_window *) tui_win_list[STATUS_WIN])
/* All the windows that are currently instantiated, in layout
order. */
extern std::vector<tui_win_info *> tui_windows;
/* Return a range adapter for iterating over TUI windows. */
static inline std::vector<tui_win_info *> &
all_tui_windows ()
{
return tui_windows;
}
/* Data Manipulation Functions. */
extern int tui_term_height (void);
extern void tui_set_term_height_to (int);
extern int tui_term_width (void);
extern void tui_set_term_width_to (int);
extern struct tui_win_info *tui_win_with_focus (void);
extern bool tui_win_resized ();
extern void tui_set_win_resized_to (bool);
extern struct tui_win_info *tui_next_win (struct tui_win_info *);
extern struct tui_win_info *tui_prev_win (struct tui_win_info *);
extern unsigned int tui_tab_width;
#endif /* TUI_TUI_DATA_H */