binutils-gdb/gdb/testsuite/gdb.threads/vfork-multi-thread.exp

# Copyright 2022 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/>.

# Test that a multi-threaded program doing a vfork doesn't miss breakpoints.
#
# When a program vforks, its address space is shared with the parent.  When we
# detach a vfork child, we must keep breakpoints out of that shared address space
# until the child either exits or execs, so that the child does not hit a
# breakpoint while out of GDB's control.  During that time, threads from
# the parent must be held stopped, otherwise they could miss breakpoints.
#
# The thread that did the vfork is suspended by the kernel, so it's not a
# concern.  The other threads need to be manually stopped by GDB and resumed
# once the vfork critical region is done.
#
# This test spawns one thread that calls vfork.  Meanwhile, the main thread
# crosses a breakpoint.  A buggy GDB would let the main thread run while
# breakpoints are removed, so the main thread would miss the breakpoint and run
# until exit.

standard_testfile

if { [build_executable "failed to prepare" ${testfile} ${srcfile} {debug pthreads}] } {
    return
}

set any "\[^\r\n\]*"

# A bunch of util procedures to continue an inferior to an expected point.

proc continue_to_parent_breakpoint {} {
    gdb_test "continue" \
	"hit Breakpoint .* should_break_here .*" \
	"continue parent to breakpoint"
}

proc continue_to_parent_end {} {
    gdb_test "continue" "Inferior 1.*exited with code 06.*" \
	"continue parent to end"
}

# Run the test with the given GDB settings.

proc do_test { target-non-stop non-stop follow-fork-mode detach-on-fork schedule-multiple } {
    save_vars { ::GDBFLAGS } {
	append ::GDBFLAGS " -ex \"maintenance set target-non-stop ${target-non-stop}\""
	append ::GDBFLAGS " -ex \"set non-stop ${non-stop}\""
	clean_restart ${::binfile}
    }

    gdb_test_no_output "set follow-fork-mode ${follow-fork-mode}"
    gdb_test_no_output "set detach-on-fork ${detach-on-fork}"
    gdb_test_no_output "set schedule-multiple ${schedule-multiple}"

    # The message about thread 2 of inferior 1 exiting happens at a somewhat
    # unpredictable moment, it's simpler to silence it than to try to match it.
    gdb_test_no_output "set print thread-events off"

    if { ![runto_main] } {
	return
    }

    # The main thread is expected to hit this breakpoint.
    gdb_test "break should_break_here" "Breakpoint $::decimal at .*"

    continue_to_parent_breakpoint
    continue_to_parent_end
}

# We only test with follow-fork-mode=parent and detach-on-fork=on at the
# moment, but the loops below are written to make it easy to add other values
# on these axes in the future.

foreach_with_prefix target-non-stop {auto on off} {
    foreach_with_prefix non-stop {off on} {
	foreach_with_prefix follow-fork-mode {parent} {
	    foreach_with_prefix detach-on-fork {on} {
		foreach_with_prefix schedule-multiple {off on} {
		    do_test ${target-non-stop} ${non-stop} ${follow-fork-mode} ${detach-on-fork} ${schedule-multiple}
		}
	    }
	}
    }
}