From 363429d593eb1eb17f3f2cf6c247f60fadf660d9 Mon Sep 17 00:00:00 2001 From: Kevin Buettner Date: Mon, 27 Feb 2023 16:11:37 -0700 Subject: [PATCH] QUIT processing w/ explicit throw for gdb_exception_forced_quit This commit contains changes which have an explicit throw for gdb_exception_forced_quit, or, in a couple of cases for gdb_exception, but with a throw following a check to see if 'reason' is RETURN_FORCED_QUIT. Most of these are straightforward - it made sense to continue to allow an existing catch of gdb_exception to also catch gdb_exception_quit; in these cases, a catch/throw for gdb_exception_forced_quit was added. There are two cases, however, which deserve a more detailed explanation. 1) remote_fileio_request in gdb/remote-fileio.c: The try block calls do_remote_fileio_request which can (in turn) call one of the functions in remote_fio_func_map[]. Taking the first one, remote_fileio_func_open(), we have the following call path to maybe_quit(): remote_fileio_func_open(remote_target*, char*) -> target_read_memory(unsigned long, unsigned char*, long) -> target_read(target_ops*, target_object, char const*, unsigned char*, unsigned long, long) -> maybe_quit() Since there is a path to maybe_quit(), we must ensure that the catch block is not permitted to swallow a QUIT representing a SIGTERM. However, for this case, we must take care not to change the way that Ctrl-C / SIGINT is handled; we want to send a suitable EINTR reply to the remote target should that happen. That being the case, I added a catch/throw for gdb_exception_forced_quit. I also did a bit of rewriting here, adding a catch for gdb_exception_quit in favor of checking the 'reason' code in the catch block for gdb_exception. 2) mi_execute_command in gdb/mi/mi-main.c: The try block calls captured_mi_execute_command(); there exists a call path to maybe_quit(): captured_mi_execute_command(ui_out*, mi_parse*) -> mi_cmd_execute(mi_parse*) -> get_current_frame() -> get_prev_frame_always_1(frame_info*) -> frame_register_unwind_location(frame_info*, int, int*, lval_type*, unsigned long*, int*) -> frame_register_unwind(frame_info*, int, int*, int*, lval_type*, unsigned long*, int*, unsigned char*) -> value_entirely_available(value*) -> value_fetch_lazy(value*) -> value_fetch_lazy_memory(value*) -> read_value_memory(value*, long, int, unsigned long, unsigned char*, unsigned long) -> maybe_quit() That being the case, we can't allow the exception handler (catch block) to swallow a gdb_exception_quit for SIGTERM. However, it does seem reasonable to output the exception via the mi interface so that some suitable message regarding SIGTERM might be printed; therefore, I check the exception's 'reason' field for RETURN_FORCED_QUIT and do a throw for this case. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=26761 Tested-by: Tom de Vries Approved-By: Pedro Alves --- gdb/event-top.c | 2 ++ gdb/mi/mi-main.c | 4 ++++ gdb/remote-fileio.c | 13 +++++++++---- 3 files changed, 15 insertions(+), 4 deletions(-) diff --git a/gdb/event-top.c b/gdb/event-top.c index f0a3f0d418c..36863292696 100644 --- a/gdb/event-top.c +++ b/gdb/event-top.c @@ -1281,6 +1281,8 @@ async_disconnect (gdb_client_data arg) gdb_puts ("Could not kill the program being debugged", gdb_stderr); exception_print (gdb_stderr, exception); + if (exception.reason == RETURN_FORCED_QUIT) + throw; } for (inferior *inf : all_inferiors ()) diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c index 84a95a24684..0013e5dfafd 100644 --- a/gdb/mi/mi-main.c +++ b/gdb/mi/mi-main.c @@ -1952,6 +1952,10 @@ mi_execute_command (const char *cmd, int from_tty) somewhere. */ mi_print_exception (command->token, result); mi_out_rewind (current_uiout); + + /* Throw to a higher level catch for SIGTERM sent to GDB. */ + if (result.reason == RETURN_FORCED_QUIT) + throw; } bpstat_do_actions (); diff --git a/gdb/remote-fileio.c b/gdb/remote-fileio.c index 3ff2a65b0ec..69b409708a3 100644 --- a/gdb/remote-fileio.c +++ b/gdb/remote-fileio.c @@ -1191,12 +1191,17 @@ remote_fileio_request (remote_target *remote, char *buf, int ctrlc_pending_p) { do_remote_fileio_request (remote, buf); } + catch (const gdb_exception_forced_quit &ex) + { + throw; + } + catch (const gdb_exception_quit &ex) + { + remote_fileio_reply (remote, -1, FILEIO_EINTR); + } catch (const gdb_exception &ex) { - if (ex.reason == RETURN_QUIT) - remote_fileio_reply (remote, -1, FILEIO_EINTR); - else - remote_fileio_reply (remote, -1, FILEIO_EIO); + remote_fileio_reply (remote, -1, FILEIO_EIO); } } -- 2.30.2