binutils-gdb/gdb/testsuite/gdb.threads/process-dies-while-detaching.exp

# Copyright 2016 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/>.

# This test spawns a few threads that immediately exit the whole
# process.  On targets where the debugger needs to detach from each
# thread individually (such as on the Linux kernel), the debugger must
# handle the case of the process exiting while the detach is ongoing.
#
# Similarly, the process can also be killed from outside the debugger
# (e.g., with SIGKILL), _before_ the user requests a detach.  The
# debugger must likewise detach gracefully.
#
# The testcase actually builds two variants of the test program:
# single-process, and multi-process.  In the multi-process variant,
# the test program forks, and it's the fork child that spawns threads
# that exit just while the process is being detached from.  The fork
# parent waits for its child to exit, so if GDB fails to detach from
# the child correctly, the parent hangs.  Because continuing the
# parent can mask failure to detach from the child correctly (e.g.,
# due to waitpid(-1,...) calls deep in the target layers managing to
# reap the child), we try immediately detaching from the parent too,
# and observing whether the parent exits via standard output.
#
# Normally, if testing with "target remote" against gdbserver, then
# after detaching from all attached processes, gdbserver exits.
# However, when gdbserver detaches from a process that is its own
# direct child, gdbserver does not exit immediately.  Instead it
# "joins" (waits for) the child, only exiting when the child itself
# exits too.  Thus, on Linux, if gdbserver fails to detach from the
# zombie child's threads correctly (or rather, reap them), it'll hang,
# because the leader thread will only return an exit status after all
# threads are reaped.  We test that as well.

standard_testfile

# Test that GDBserver exits.

proc test_server_exit {} {
    global server_spawn_id

    set test "server exits"
    gdb_expect {
	-i $server_spawn_id
	eof {
	    pass $test
	    wait -i $server_spawn_id
	    unset server_spawn_id
	}
	timeout {
	    fail "$test (timeout)"
	}
    }
}

# If RESULT is not zero, make the caller return.

proc return_if_fail { result } {
    if {$result != 0} {
	return -code return
    }
}

# Detach from a process, and ensure that it exits after detaching.
# This relies on inferior I/O.

proc detach_and_expect_exit {test} {
    global decimal
    global gdb_spawn_id
    global inferior_spawn_id
    global gdb_prompt

    return_if_fail [gdb_test_multiple "detach" $test {
	-re "Detaching from .*, process $decimal" {
	}
    }]

    set saw_prompt 0
    set saw_inf_exit 0
    while { !$saw_prompt && ! $saw_inf_exit } {
	# We don't know what order the interesting things will arrive in.
	# Using a pattern of the form 'x|y|z' instead of -re x ... -re y
	# ... -re z ensures that expect always chooses the match that
	# occurs leftmost in the input, and not the pattern appearing
	# first in the script that occurs anywhere in the input, so that
	# we don't skip anything.
	return_if_fail [gdb_test_multiple "" $test {
	    -i "$inferior_spawn_id $gdb_spawn_id"
	    -re "(exited, status=0)|($gdb_prompt )" {
		if {[info exists expect_out(1,string)]} {
		    verbose -log "saw inferior exit"
		    set saw_inf_exit 1
		} elseif {[info exists expect_out(2,string)]} {
		    verbose -log "saw prompt"
		    set saw_prompt 1
		}
		array unset expect_out
	    }
	}]
    }

    pass $test
}

# Run to _exit in the child.

proc continue_to_exit_bp {} {
    gdb_breakpoint "_exit" temporary
    gdb_continue_to_breakpoint "_exit" ".*_exit.*"
}

# If testing single-process, simply detach from the process.
#
# If testing multi-process, first detach from the child, then detach
# from the parent and confirm that the parent exits, thus ensuring
# we've detached from the child successfully, as the parent hangs in
# its waitpid call otherwise.
#
# If connected with "target remote", make sure gdbserver exits.
#
# CMD indicates what to do with the parent after detaching the child.
# Can be either "detach" to detach, or "continue", to continue to
# exit.  If "continue", then CONTINUE_RE is the regexp to expect.
# Defaults to normal exit output.
#
proc do_detach {multi_process cmd {continue_re ""}} {
    global decimal
    global server_spawn_id

    if {$continue_re == ""} {
	set continue_re "exited normally.*"
    }

    set is_remote [expr {[target_info exists gdb_protocol]
			 && [target_info gdb_protocol] == "remote"}]

    if {$multi_process} {
	gdb_test "detach" "Detaching from .*, process $decimal" \
	    "detach child"

	gdb_test "inferior 1" "\[Switching to inferior $decimal\].*" \
	    "switch to parent"

	if {$cmd == "detach"} {
	    # Make sure that detach works and that the parent process
	    # exits cleanly.
	    detach_and_expect_exit "detach parent"
	} elseif {$cmd == "continue"} {
	    # Make sure that continuing works and that the parent process
	    # exits cleanly.
	    gdb_test "continue" $continue_re
	} else {
	    perror "unhandled command: $cmd"
	}
    } else {
	if $is_remote {
	    set extra "\r\nEnding remote debugging\."
	} else {
	    set extra ""
	}
	if {$cmd == "detach"} {
	    gdb_test "detach" "Detaching from .*, process $decimal$extra"
	} elseif {$cmd == "continue"} {
	    gdb_test "continue" $continue_re
	} else {
	    perror "unhandled command: $cmd"
	}
    }

    # When connected in "target remote" mode, the server should exit
    # when there are no processes left to debug.
    if { $is_remote && [info exists server_spawn_id]} {
	test_server_exit
    }
}

# Test detaching from a process that dies just while GDB is detaching.

proc test_detach {multi_process cmd} {
    with_test_prefix "detach" {
	global binfile

	clean_restart ${binfile}

	if ![runto_main] {
	    fail "can't run to main"
	    return -1
	}

	if {$multi_process} {
	    gdb_test_no_output "set detach-on-fork off"
	    gdb_test_no_output "set follow-fork-mode child"
	}

	# Run to _exit in the child.
	continue_to_exit_bp

	do_detach $multi_process $cmd
    }
}

# Same as test_detach, except set a watchpoint before detaching.

proc test_detach_watch {multi_process cmd} {
    with_test_prefix "watchpoint" {
	global binfile decimal

	clean_restart ${binfile}

	if ![runto_main] {
	    fail "can't run to main"
	    return -1
	}

	if {$multi_process} {
	    gdb_test_no_output "set detach-on-fork off"
	    gdb_test_no_output "set follow-fork-mode child"

	    gdb_breakpoint "child_function" temporary
	    gdb_continue_to_breakpoint "child_function" ".*"
	}

	# Set a watchpoint in the child.
	gdb_test "watch globalvar" ".* watchpoint $decimal: globalvar"

	# Continue to the _exit breakpoint.  This arms the watchpoint
	# registers in all threads.  Detaching will thus need to clear
	# them out, and handle the case of the thread disappearing
	# while doing that (on targets that need to detach from each
	# thread individually).
	continue_to_exit_bp

	do_detach $multi_process $cmd
    }
}

# Test detaching from a process that dies _before_ GDB starts
# detaching.

proc test_detach_killed_outside {multi_process cmd} {
    with_test_prefix "killed outside" {
	global binfile

	clean_restart ${binfile}

	if ![runto_main] {
	    fail "can't run to main"
	    return -1
	}

	gdb_test_no_output "set breakpoint always-inserted on"

	if {$multi_process} {
	    gdb_test_no_output "set detach-on-fork off"
	    gdb_test_no_output "set follow-fork-mode child"
	}

	# Run to _exit in the child.
	continue_to_exit_bp

	set childpid [get_integer_valueof "mypid" -1]
	if { $childpid == -1 } {
	    untested "failed to extract child pid"
	    return -1
	}

	remote_exec target "kill -9 ${childpid}"

	# Give it some time to die.
	sleep 2

	if {$multi_process} {
	    set continue_re "exited with code 02.*"
	} else {
	    set continue_re "terminated with signal SIGKILL.*"
	}
	do_detach $multi_process $cmd $continue_re
    }
}

# The test proper.  MULTI_PROCESS is true if testing the multi-process
# variant.

proc do_test {multi_process cmd} {
    global testfile srcfile binfile

    if {$multi_process && $cmd == "detach"
	&& [target_info exists gdb,noinferiorio]} {
	# This requires inferior I/O to tell whether both the parent
	# and child exit successfully.
	return
    }

    set binfile [standard_output_file ${testfile}-$multi_process-$cmd]
    set options {debug pthreads}
    if {$multi_process} {
	lappend options "additional_flags=-DMULTIPROCESS"
    }

    if {[build_executable "failed to build" \
	     $testfile-$multi_process-$cmd $srcfile $options] == -1} {
	return -1
    }

    test_detach $multi_process $cmd
    test_detach_watch $multi_process $cmd
    test_detach_killed_outside $multi_process $cmd
}

foreach multi_process {0 1} {
    set mode [expr {$multi_process ? "multi-process" : "single-process"}]
    foreach cmd {"detach" "continue"} {
	with_test_prefix "$mode: $cmd" {
	    do_test $multi_process $cmd
	}
    }
}