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

   1 # This testcase is part of GDB, the GNU debugger.
   2 #
   3 # Copyright 2013-2021 Free Software Foundation, Inc.
   4 #
   5 # This program is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU General Public License as published by
   7 # the Free Software Foundation; either version 3 of the License, or
   8 # (at your option) any later version.
   9 #
  10 # This program is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 # GNU General Public License for more details.
  14 #
  15 # You should have received a copy of the GNU General Public License
  16 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17
  18 # Regression test for a bug that would go like this:
  19 #
  20 # - Run to a breakpoint that is hit by two threads (A and B)
  21 #   simultaneously.
  22 #
  23 # - One of the breakpoint hits is processed (e.g., thread A) and
  24 #   causes a user-visible stop.  The other (thread B) is left pending.
  25 #
  26 # - The user deletes the breakpoint with "del", which causes a
  27 #   confirmation query.
  28 #
  29 # - By mistake, that would result in the target being left with async
  30 #   enabled, even though it wasn't to begin with.
  31 #
  32 # - GDB reacts to target async enablement by polling for target
  33 #   events.  As no thread is resumed the target replies
  34 #   TARGET_WAITKIND_NO_RESUMED.
  35 #
  36 # - The user continues the program, expecting it to exit.  The thread
  37 #   that has an event pending (thread B) is not really resumed.
  38 #
  39 # - But, nothing signals the event loop that there's a pending event
  40 #   waiting to be collected for thread B, so that event is never
  41 #   processed, thread B is never resumed and the program never exits.
  42 #
  43 # Ref: https://sourceware.org/ml/gdb-patches/2015-01/msg00592.html
  44
  45 standard_testfile
  46
  47 if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug pthreads}] == -1} {
  48     return -1
  49 }
  50
  51 proc test {} {
  52     global srcfile gdb_prompt
  53
  54     if ![runto_main] {
  55         return -1
  56     }
  57
  58     delete_breakpoints
  59
  60     set bp_line [gdb_get_line_number "set break here" $srcfile]
  61
  62     gdb_breakpoint "break_function"
  63     gdb_continue_to_breakpoint "cont to break_function" ".*$srcfile:$bp_line\r\n.*"
  64
  65     # Do something that causes a query/secondary prompt.
  66
  67     set test "delete breakpoints, answer prompt"
  68     set saw_prompt 0
  69     gdb_test_multiple "delete breakpoints" $test {
  70         -re "Delete all breakpoints.*y or n.*$" {
  71             set saw_prompt 1
  72             send_gdb "y\n"
  73             exp_continue
  74         }
  75         -re "$gdb_prompt $" {
  76             gdb_assert $saw_prompt $test
  77         }
  78     }
  79
  80     gdb_continue_to_end "" "continue" 1
  81 }
  82
  83 # Test a few times to make sure an event is left pending.  At the time
  84 # of writing, the bug always triggers, but that might naturally depend
  85 # on machine.
  86 for {set i 1} {$i <= 10} {incr i} {
  87     with_test_prefix "iter $i" {
  88         test
  89     }
  90 }