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
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ChangeLog-1998-2003
tui-command.c
tui-command.h
tui-data.c
tui-data.h
tui-disasm.c
tui-disasm.h
tui-file.c
tui-file.h
tui-hooks.c
tui-hooks.h
tui-interp.c
tui-io.c
tui-io.h
tui-layout.c
tui-layout.h
tui-location.c
tui-location.h
tui-out.c
tui-out.h
tui-regs.c
tui-regs.h
tui-source.c
tui-source.h
tui-stack.c
tui-stack.h
tui-win.c
tui-win.h
tui-wingeneral.c
tui-wingeneral.h
tui-winsource.c
tui-winsource.h
tui.c
tui.h