# Copyright 2008-2020 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 attaching to a program that is constantly spawning short-lived
# threads.  The stresses the edge cases of attaching to threads that
# have just been created or are in process of dying.  In addition, the
# test attaches, debugs, detaches, reattaches in a loop a few times,
# to stress the behavior of the debug API around detach (some systems
# end up leaving stale state behind that confuse the following
# attach).

# Return true if the running version of DejaGnu is known to not be
# able to run this test.
proc bad_dejagnu {} {
    set dj_ver [dejagnu_version]
    set dj_ver_major [lindex $dj_ver 0]
    set dj_ver_minor [lindex $dj_ver 1]

    # DejaGnu versions prior to 1.6 manage to kill the wrong process
    # due to PID-reuse races.  Since this test spawns many threads, it
    # widens the race window a whole lot, enough that the inferior is
    # often killed, and thus the test randomly fails.  See:
    # http://lists.gnu.org/archive/html/dejagnu/2015-07/msg00005.html
    # The fix added a close_wait_program procedure.  If that procedure
    # is defined, and DejaGnu is older than 1.6, assume that means the
    # fix was backported.
    if {$dj_ver_major == 1
	&& ($dj_ver_minor < 6 && [info procs close_wait_program] == "")} {
	return 1
    }

    return 0
}

if {[bad_dejagnu]} {
    unsupported "broken DejaGnu"
    return 0
}

if {![can_spawn_for_attach]} {
    return 0
}

standard_testfile

# The test proper.  See description above.

proc test {} {
    global binfile
    global gdb_prompt
    global decimal

    clean_restart ${binfile}

    set test_spawn_id [spawn_wait_for_attach $binfile]
    set testpid [spawn_id_get_pid $test_spawn_id]

    set attempts 10
    for {set attempt 1} { $attempt <= $attempts } { incr attempt } {
	with_test_prefix "iter $attempt" {
	    set attached 0
	    set eperm 0
	    set test "attach"
	    gdb_test_multiple "attach $testpid" $test {
		-re "new threads in iteration" {
		    # Seen when "set debug libthread_db" is on.
		    exp_continue
		}
		-re "warning: Cannot attach to lwp $decimal: Operation not permitted" {
		    # On Linux, PTRACE_ATTACH sometimes fails with
		    # EPERM, even though /proc/PID/status indicates
		    # the thread is running.
		    set eperm 1
		    exp_continue
		}
		-re "debugger service failed.*$gdb_prompt $" {
		    fail $test
		}
		-re "$gdb_prompt $" {
		    if {$eperm} {
			xfail "$test (EPERM)"
		    } else {
			pass $test
		    }
		}
		-re "Attaching to program.*process $testpid.*$gdb_prompt $" {
		    pass $test
		}
	    }

	    # Sleep a bit and try updating the thread list.  We should
	    # know about all threads already at this point.  If we see
	    # "New Thread" or similar being output, then "attach" is
	    # failing to actually attach to all threads in the process,
	    # which would be a bug.
	    sleep 1

	    set test "no new threads"
	    set status 1
	    gdb_test_multiple "info threads" $test -lbl {
		-re "\r\n\[^\r\n\]*New " {
		    set status 0
		    exp_continue
		}
		-re -wrap "" {
		    if { $status == 1 } {
			pass $gdb_test_name
		    } else {
			fail $gdb_test_name
		    }
		}
	    }

	    # Force breakpoints always inserted, so that threads we might
	    # have failed to attach to hit them even when threads we do
	    # know about are stopped.
	    gdb_test_no_output "set breakpoint always-inserted on"

	    # Run to a breakpoint a few times.  A few threads should spawn
	    # and die meanwhile.  This checks that thread creation/death
	    # events carry on correctly after attaching.  Also, be
	    # detaching from the program and reattaching, we check that
	    # the program doesn't die due to gdb leaving a pending
	    # breakpoint hit on a new thread unprocessed.
	    gdb_test "break break_fn" "Breakpoint.*"

	    # Wait a bit, to give time for most threads to hit the
	    # breakpoint, including threads we might have failed to
	    # attach.
	    sleep 2

	    set bps 3
	    for {set bp 1} { $bp <= $bps } { incr bp } {
		gdb_test "continue" "Breakpoint.*" "break at break_fn: $bp"
	    }

	    if {$attempt < $attempts} {
		# Kick the time out timer for another round.
		gdb_test "print again = 1" " = 1" "reset timer in the inferior"
		# Show the time we had left in the logs, in case
		# something goes wrong.
		gdb_test "print seconds_left" " = .*"

		gdb_test "detach" "Detaching from.*"
	    } else {
		gdb_test "kill" "" "kill process" "Kill the program being debugged.*y or n. $" "y"
	    }

	    gdb_test_no_output "set breakpoint always-inserted off"
	    delete_breakpoints
	}
    }
    kill_wait_spawned_process $test_spawn_id
}

# The test program exits after a while, in case GDB crashes.  Make it
# wait at least as long as we may wait before declaring a time out
# failure.
set options { "additional_flags=-DTIMEOUT=$timeout" debug pthreads }

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

test