From: Pedro Alves Date: Mon, 14 Jul 2014 18:55:32 +0000 (+0100) Subject: Remove the target from the event loop while in secondary prompts X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=93d6eb10ede1d8b72b274345c63f66439eaf7fd0;p=binutils-gdb.git Remove the target from the event loop while in secondary prompts If a pagination prompt triggers while the target is running, and the target exits before the user responded to the pagination query, this happens: Starting program: foo ---Type to continue, or q to quit---No unwaited-for children left. Couldn't get registers: No such process. Couldn't get registers: No such process. Couldn't get registers: No such process. (gdb) Couldn't get registers: No such process. (gdb) To reiterate, the user hasn't replied to the pagination prompt above. A pagination query nests an event loop (in gdb_readline_wrapper). In async mode, in addition to stdin and signal handlers, we'll have the target also installed in the event loop still. So if the target reports an event, that wakes up the nested event loop, which calls into fetch_inferior_event etc. to handle the event which generates further output, all while we should be waiting for pagination confirmation... (TBC, any target event that generates output ends up spuriously waking up the pagination, though exits seem to be the worse kind.) I've played with a couple different approaches to fixing this, while at the same time trying to avoid being invasive. Both revolve around not listening to target events while in a pagination prompt (doing anything else I think would be a much bigger change). The approach taken just removes the target from the event loop while within gdb_readline_wrapper. The other approach used gdb_select directly, with only input_fd installed, but that had the issue that it didn't handle the async signal handlers, and turned out to be a bit more code than the first version. gdb/ 2014-07-14 Pedro Alves PR gdb/17072 * top.c: Include "inf-loop.h". (struct gdb_readline_wrapper_cleanup) : New field. (gdb_readline_wrapper_cleanup): Make the target async again, if it was async before. (gdb_readline_wrapper): Store whether the target is async, and make it sync. gdb/testsuite/ 2014-07-14 Pedro Alves PR gdb/17072 * gdb.base/paginate-inferior-exit.c: New file. * gdb.base/paginate-inferior-exit.exp: New file. --- diff --git a/gdb/ChangeLog b/gdb/ChangeLog index cd13f70db26..96d507163a0 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,14 @@ +2014-07-14 Pedro Alves + + PR gdb/17072 + * top.c: Include "inf-loop.h". + (struct gdb_readline_wrapper_cleanup) : New + field. + (gdb_readline_wrapper_cleanup): Make the target async again, if it + was async before. + (gdb_readline_wrapper): Store whether the target is async, and + make it sync. + 2014-07-14 Pedro Alves PR gdb/17072 diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index f6c963df195..6d3fa569b98 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2014-07-14 Pedro Alves + + PR gdb/17072 + * gdb.base/paginate-inferior-exit.c: New file. + * gdb.base/paginate-inferior-exit.exp: New file. + 2014-07-14 Pedro Alves PR gdb/17072 diff --git a/gdb/testsuite/gdb.base/paginate-inferior-exit.c b/gdb/testsuite/gdb.base/paginate-inferior-exit.c new file mode 100644 index 00000000000..e741785e72d --- /dev/null +++ b/gdb/testsuite/gdb.base/paginate-inferior-exit.c @@ -0,0 +1,32 @@ +/* This testcase is part of GDB, the GNU debugger. + + Copyright 2014 Free Software Foundation, Inc. + + 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 . */ + +#include + +static void +after_sleep (void) +{ + return; /* after sleep */ +} + +int +main (void) +{ + sleep (3); + after_sleep (); + return 0; +} diff --git a/gdb/testsuite/gdb.base/paginate-inferior-exit.exp b/gdb/testsuite/gdb.base/paginate-inferior-exit.exp new file mode 100644 index 00000000000..0e37be97994 --- /dev/null +++ b/gdb/testsuite/gdb.base/paginate-inferior-exit.exp @@ -0,0 +1,85 @@ +# Copyright (C) 2014 Free Software Foundation, Inc. + +# 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 . + +# A collection of tests related to running execution commands directly +# from the command line, with "-ex". + +standard_testfile + +if {[build_executable "failed to prepare" $testfile $srcfile debug] == -1} { + return -1 +} + +# Test paginating while printing about the inferior having exited. +# +proc test_paginate_inferior_exited {} { + global binfile + global gdb_prompt pagination_prompt + global inferior_exited_re + + with_test_prefix "paginate" { + clean_restart $binfile + + if ![runto_main] then { + fail "Can't run to main" + return 0 + } + + # Force pagination. + gdb_test_no_output "set height 2" + + set test "continue to pagination" + + # Wait for the "Starting program" line, indicating the program + # is running. + set saw_starting 0 + gdb_test_multiple "continue" $test { + -re "$pagination_prompt" { + if {$saw_starting} { + pass $test + } else { + send_gdb "\n" + exp_continue + } + } + -re "Continuing" { + set saw_starting 1 + exp_continue + } + -notransfer -re "" { + # Otherwise gdb_test_multiple considers this an error. + exp_continue + } + } + + # We're now stopped in a pagination output while handling a + # target event, trying to print about the program exiting. + set test "inferior exits normally" + + send_gdb "\n" + gdb_test_multiple "" $test { + -re "$inferior_exited_re normally.*$gdb_prompt $" { + pass $test + } + } + + gdb_test "p 1" " = 1" "GDB accepts further input" + + # In case the board file wants to send further commands. + gdb_test_no_output "set height unlimited" + } +} + +test_paginate_inferior_exited diff --git a/gdb/top.c b/gdb/top.c index 93a4a1694cf..19c88f9ffdd 100644 --- a/gdb/top.c +++ b/gdb/top.c @@ -68,6 +68,7 @@ #include "ui-out.h" #include "cli-out.h" #include "tracepoint.h" +#include "inf-loop.h" extern void initialize_all_files (void); @@ -766,6 +767,9 @@ struct gdb_readline_wrapper_cleanup { void (*handler_orig) (char *); int already_prompted_orig; + + /* Whether the target was async. */ + int target_is_async_orig; }; static void @@ -789,6 +793,9 @@ gdb_readline_wrapper_cleanup (void *arg) after_char_processing_hook = saved_after_char_processing_hook; saved_after_char_processing_hook = NULL; + if (cleanup->target_is_async_orig) + target_async (inferior_event_handler, 0); + xfree (cleanup); } @@ -805,8 +812,13 @@ gdb_readline_wrapper (char *prompt) cleanup->already_prompted_orig = rl_already_prompted; + cleanup->target_is_async_orig = target_is_async_p (); + back_to = make_cleanup (gdb_readline_wrapper_cleanup, cleanup); + if (cleanup->target_is_async_orig) + target_async (NULL, NULL); + /* Display our prompt and prevent double prompt display. */ display_gdb_prompt (prompt); rl_already_prompted = 1;