From 96e3f4e3c32865fecdb266c2a41532337c75e316 Mon Sep 17 00:00:00 2001 From: Kevin Buettner Date: Mon, 27 Feb 2023 16:11:37 -0700 Subject: Forced quit cases handled by resetting sync_quit_force_run During my audit of the use of gdb_exception with regard to QUIT processing, I found a try/catch in the scoped_switch_fork_info destructor. Static analysis found this call path from the destructor to maybe_quit(): scoped_switch_fork_info::~scoped_switch_fork_info() -> remove_breakpoints() -> remove_breakpoint(bp_location*) -> remove_breakpoint_1(bp_location*, remove_bp_reason) -> memory_validate_breakpoint(gdbarch*, bp_target_info*) -> target_read_memory(unsigned long, unsigned char*, long) -> target_read(target_ops*, target_object, char const*, unsigned char*, unsigned long, long) -> maybe_quit() Since it's not safe to do a 'throw' from a destructor, we simply call set_quit_flag and, for gdb_exception_forced_quit, also set sync_quit_force_run. This will cause the appropriate exception to be rethrown at the next QUIT check. Another case is the try / catch in tui_getc() in tui-io.c. The existing catch swallows the exception. I've added a catch for 'gdb_exception_forced_quit', which also swallows the exception, but also sets sync_quit_force_run and calls set_quit_flag in order to restart forced quit processing at the next QUIT check. This is required because it isn't safe to throw into/through readline. Thanks to Pedro Alves for suggesting this idea. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=26761 Tested-by: Tom de Vries Approved-By: Pedro Alves --- gdb/linux-fork.c | 12 ++++++++++++ gdb/tui/tui-io.c | 8 ++++++++ gdb/tui/tui.c | 7 +++++++ 3 files changed, 27 insertions(+) (limited to 'gdb') diff --git a/gdb/linux-fork.c b/gdb/linux-fork.c index 61545b8..a6e74c0 100644 --- a/gdb/linux-fork.c +++ b/gdb/linux-fork.c @@ -430,6 +430,18 @@ public: fork_load_infrun_state (m_oldfp); insert_breakpoints (); } + catch (const gdb_exception_quit &ex) + { + /* We can't throw from a destructor, so re-set the quit flag + for later QUIT checking. */ + set_quit_flag (); + } + catch (const gdb_exception_forced_quit &ex) + { + /* Like above, but (eventually) cause GDB to terminate by + setting sync_quit_force_run. */ + set_force_quit_flag (); + } catch (const gdb_exception &ex) { warning (_("Couldn't restore checkpoint state in %s: %s"), diff --git a/gdb/tui/tui-io.c b/gdb/tui/tui-io.c index a17cf38..7752701 100644 --- a/gdb/tui/tui-io.c +++ b/gdb/tui/tui-io.c @@ -1271,6 +1271,14 @@ tui_getc (FILE *fp) { return tui_getc_1 (fp); } + catch (const gdb_exception_forced_quit &ex) + { + /* As noted below, it's not safe to let an exception escape + to newline, so, for this case, reset the quit flag for + later QUIT checking. */ + set_force_quit_flag (); + return 0; + } catch (const gdb_exception &ex) { /* Just in case, don't ever let an exception escape to readline. diff --git a/gdb/tui/tui.c b/gdb/tui/tui.c index cdae9ff..3604194 100644 --- a/gdb/tui/tui.c +++ b/gdb/tui/tui.c @@ -122,6 +122,13 @@ tui_rl_switch_mode (int notused1, int notused2) tui_enable (); } } + catch (const gdb_exception_forced_quit &ex) + { + /* Ideally, we'd do a 'throw' here, but as noted above, we can't + do that, so, instead, we'll set the necessary flags so that + a later QUIT check will restart the forced quit. */ + set_force_quit_flag (); + } catch (const gdb_exception &ex) { exception_print (gdb_stderr, ex); -- cgit v1.1