gdb/testsuite/gdb.threads/continue-pending-after-query.exp

# This testcase is part of GDB, the GNU debugger.
#
# Copyright 2013-2021 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 <http://www.gnu.org/licenses/>.

# Regression test for a bug that would go like this:
#
# - Run to a breakpoint that is hit by two threads (A and B)
#   simultaneously.
#
# - One of the breakpoint hits is processed (e.g., thread A) and
#   causes a user-visible stop.  The other (thread B) is left pending.
#
# - The user deletes the breakpoint with "del", which causes a
#   confirmation query.
#
# - By mistake, that would result in the target being left with async
#   enabled, even though it wasn't to begin with.
#
# - GDB reacts to target async enablement by polling for target
#   events.  As no thread is resumed the target replies
#   TARGET_WAITKIND_NO_RESUMED.
#
# - The user continues the program, expecting it to exit.  The thread
#   that has an event pending (thread B) is not really resumed.
#
# - But, nothing signals the event loop that there's a pending event
#   waiting to be collected for thread B, so that event is never
#   processed, thread B is never resumed and the program never exits.
#
# Ref: https://sourceware.org/ml/gdb-patches/2015-01/msg00592.html

standard_testfile

if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug pthreads}] == -1} {
    return -1
}

proc test {} {
    global srcfile gdb_prompt

    if ![runto_main] {
	return -1
    }

    delete_breakpoints

    set bp_line [gdb_get_line_number "set break here" $srcfile]

    gdb_breakpoint "break_function"
    gdb_continue_to_breakpoint "cont to break_function" ".*$srcfile:$bp_line\r\n.*"

    # Do something that causes a query/secondary prompt.

    set test "delete breakpoints, answer prompt"
    set saw_prompt 0
    gdb_test_multiple "delete breakpoints" $test {
	-re "Delete all breakpoints.*y or n.*$" {
	    set saw_prompt 1
	    send_gdb "y\n"
	    exp_continue
	}
	-re "$gdb_prompt $" {
	    gdb_assert $saw_prompt $test
	}
    }

    gdb_continue_to_end "" "continue" 1
}

# Test a few times to make sure an event is left pending.  At the time
# of writing, the bug always triggers, but that might naturally depend
# on machine.
for {set i 1} {$i <= 10} {incr i} {
    with_test_prefix "iter $i" {
	test
    }
}