gdb/testsuite/gdb.threads/pending-fork-event-detach.exp

# Copyright (C) 2021-2022 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/>.

# Then, test that if we detach an inferior with a pending fork child, that
# child is correctly detached and resumes execution normally.  There are two
# kinds of "pending fork child" we test:
#
#   - resulting of a fork catchpoint: we stop at a fork catchpoint and detach.
#   - resulting of an all-stop stop on top of a non-stop target, where a fork
#     event is saved as a pending wait status.  To test this, we stepi a thread
#     while another one forks.  The stepi generally completes at least as fast
#     as the fork, so we have a chance that the stop due to the stepi being
#     complete is shown to the user while the fork event is saved for later.
#
# To verify that the child process is detached and resumes execution, we have
# it write a file on the filesystem.  If we don't see the file after a certain
# delay, it means the child was likely not detached, and the test fails.
#
# At the same time, this tests that having this pending fork event does not
# cause other problems in general.  For example, a buggy GDB / GDBserver combo
# would notice the thread of the child process of the (still unprocessed) fork
# event, and erroneously create a new inferior for it.  Once fixed, the child
# process' thread is hidden by whoever holds the pending fork event.

standard_testfile .c -touch-file.c

set touch_file_bin $binfile-touch-file

if { [is_remote target] } {
    # If the target is remote, write the file in whatever the current working
    # directory is, with a somewhat unique name.
    set touch_file_path ${testfile}-flag
} else {
    set touch_file_path [standard_output_file flag]
}

set opts [list debug "additional_flags=-DTOUCH_FILE_PATH=\"$touch_file_path\""]
if { [gdb_compile "$srcdir/$subdir/$srcfile2" $touch_file_bin executable $opts] != "" } {
    return
}

proc do_test { target-non-stop who_forks fork_function stop_mode } {
    set opts [list \
	debug \
	"additional_flags=-DFORK_FUNCTION=$fork_function" \
	"additional_flags=-DTOUCH_FILE_BIN=\"$::touch_file_bin\""]

    # WHO_FORKS says which of the main or other thread calls (v)fork.  The
    # thread that does not call (v)fork is the one who tries to step.
    if { $who_forks == "main" } {
	lappend opts "additional_flags=-DMAIN_THREAD_FORKS"
	set this_binfile ${::binfile}-main-${fork_function}
    } elseif { $who_forks == "other" } {
	lappend opts "additional_flags=-DOTHER_THREAD_FORKS"
	set this_binfile ${::binfile}-other-${fork_function}
    } else {
	error "invalid who_forks value: $who_forks"
    }

    if { [gdb_compile_pthreads "$::srcdir/$::subdir/$::srcfile" $this_binfile executable $opts] != "" } {
	return
    }

    remote_file target delete $::touch_file_path
    gdb_assert { ![remote_file target exists $::touch_file_path] } "file does not exist before test"

    save_vars { ::GDBFLAGS } {
	append ::GDBFLAGS " -ex \"maintenance set target-non-stop ${target-non-stop}\""
	clean_restart $this_binfile
    }

    if {![runto_main]} {
	fail "could not run to main"
	return
    }

    # Run until breakpoint in the second thread.
    gdb_test "break break_here" "Breakpoint $::decimal.*"
    gdb_continue_to_breakpoint "thread started"

    # Delete the breakpoint so the thread doesn't do a step-over.
    delete_breakpoints

    # Let the forking thread make progress during the step.
    gdb_test "p release_forking_thread = 1" " = 1"

    # There are two "pending fork child" modes we can test here:
    #
    #   - catch: set up a "catch fork" / "catch vfork" and run to it.
    #   - stepi: stepi the non-forking thread while the forking thread,
    #     well, forks.
    if { $stop_mode == "catch" } {
	gdb_test "catch fork"
	gdb_test "catch vfork"
	gdb_test "continue" "hit Catchpoint $::decimal.*fork.*"
    } elseif { $stop_mode == "stepi" } {
	# stepi the non-forking thread.
	gdb_test "stepi"
    } else {
	error "invalid stop_mode value: $stop_mode"
    }

    # Make sure there's still a single inferior.
    gdb_test "info inferior" {\* 1 [^\r\n]+}

    gdb_test "detach"

    # After being detached, the fork child creates file ::TOUCH_FILE_PATH.
    # Seeing this file tells us the fork child was detached and executed
    # successfully.
    gdb_assert { [target_file_exists_with_timeout $::touch_file_path] } "file exists after detach"

    # Don't leave random files on the target system.
    if { [is_remote target] } {
	remote_file target delete $::touch_file_path
    }
}

foreach_with_prefix target-non-stop { auto on off } {
    foreach_with_prefix who_forks { main other } {
	foreach_with_prefix fork_function { fork vfork } {
	    foreach_with_prefix stop_mode { stepi catch } {
		do_test ${target-non-stop} $who_forks $fork_function $stop_mode
	    }
	}
    }
}