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1d506c26 | 1 | # Copyright 2023-2024 Free Software Foundation, Inc. |
fd492bf1 AB |
2 | # This program is free software; you can redistribute it and/or modify |
3 | # it under the terms of the GNU General Public License as published by | |
4 | # the Free Software Foundation; either version 3 of the License, or | |
5 | # (at your option) any later version. | |
6 | # | |
7 | # This program is distributed in the hope that it will be useful, | |
8 | # but WITHOUT ANY WARRANTY; without even the implied warranty of | |
9 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
10 | # GNU General Public License for more details. | |
11 | # | |
12 | # You should have received a copy of the GNU General Public License | |
13 | # along with this program. If not, see <http://www.gnu.org/licenses/>. | |
14 | ||
15 | # Check for a race condition where in non-stop mode, the user might | |
16 | # have a thread other than the main (original) thread selected and use | |
17 | # the 'detach' command. | |
18 | # | |
19 | # As GDB tries to detach it is possible that the main thread might | |
20 | # exit, the main thread is still running due to non-stop mode. | |
21 | # | |
22 | # GDB used to assume that the main thread would always exist when | |
23 | # processing the detach, clearly this isn't the case, and this | |
24 | # assumption would lead to assertion failures and segfaults. | |
25 | # | |
26 | # Triggering the precise timing is pretty hard, we need the main | |
27 | # thread to exit after the user has entered the 'detach' command, but | |
28 | # before GDB enters the detach implementation and stops all threads, | |
29 | # the window of opportunity for this bug is actually tiny. | |
30 | # | |
31 | # However, we can trigger this bug 100% from Python, as GDB's | |
32 | # event-loop only kicks in once we return from a Python function. | |
33 | # Thus, if we have a single Python function that causes the main | |
34 | # thread to exit, and then calls detach GDB will not have a chance to | |
35 | # handle the main thread exiting before entering the detach code. | |
36 | ||
37 | standard_testfile | |
38 | ||
39 | require allow_python_tests | |
40 | ||
41 | if {[build_executable "failed to prepare" $testfile $srcfile \ | |
42 | {debug pthreads}] == -1} { | |
43 | return -1 | |
44 | } | |
45 | ||
46 | # Run the test. When SPAWN_INFERIOR is true the inferior is started | |
47 | # as a separate process which GDB then attaches too. When | |
48 | # SPAWN_INFERIOR is false the inferior is started directly within GDB. | |
49 | ||
50 | proc run_test { spawn_inferior } { | |
51 | save_vars { ::GDBFLAGS } { | |
52 | append ::GDBFLAGS " -ex \"set non-stop on\"" | |
53 | clean_restart $::binfile | |
54 | } | |
55 | ||
56 | # Setup the inferior. When complete the main thread (#1) will | |
57 | # still be running (due to non-stop mode), while the worker thread | |
58 | # (#2) will be stopped. | |
59 | # | |
60 | # There are two setup modes, when SPAWN_INFERIOR is true we span a | |
61 | # separate process and attach to it, after the attach both threads | |
62 | # are stopped, so it is necessary to resume thread #1. | |
63 | # | |
64 | # When SPAWN_INFERIOR is false we just start the inferior within | |
65 | # GDB, in this case we place a breakpoint that will be hit by | |
66 | # thread #2. When the breakpoint is hit thread #1 will remain | |
67 | # running. | |
68 | if {$spawn_inferior} { | |
69 | set test_spawn_id [spawn_wait_for_attach $::binfile] | |
70 | set testpid [spawn_id_get_pid $test_spawn_id] | |
71 | ||
72 | set escapedbinfile [string_to_regexp $::binfile] | |
73 | gdb_test -no-prompt-anchor "attach $testpid" \ | |
74 | "Attaching to program.*`?$escapedbinfile'?, process $testpid.*" \ | |
75 | "attach to the inferior" | |
76 | ||
77 | # Attaching to a multi-threaded application in non-stop mode | |
78 | # can result in thread stops being reported after the prompt | |
79 | # is displayed. | |
80 | # | |
81 | # Send a simple command now just to resync the command prompt. | |
82 | gdb_test "p 1 + 2" " = 3" | |
83 | ||
84 | # Set thread 1 (the current thread) running again. | |
85 | gdb_test "continue&" | |
86 | } else { | |
87 | if {![runto_main]} { | |
88 | return -1 | |
89 | } | |
90 | ||
91 | gdb_breakpoint "breakpt" | |
92 | gdb_continue_to_breakpoint "run to breakpoint" | |
93 | } | |
94 | ||
95 | # Switch to thread 2. | |
96 | gdb_test "thread 2" \ | |
97 | [multi_line \ | |
98 | "Switching to thread 2\[^\r\n\]*" \ | |
99 | "#0\\s+.*"] | |
100 | ||
101 | # Create a Python function that sets a variable in the inferior and | |
102 | # then detaches. Setting the variable in the inferior will allow the | |
103 | # main thread to exit, we even sleep for a short while in order to | |
104 | # give the inferior a chance to exit. | |
105 | # | |
106 | # However, we don't want GDB to notice the exit before we call detach, | |
107 | # which is why we perform both these actions from a Python function. | |
108 | gdb_test_multiline "Create worker function" \ | |
109 | "python" "" \ | |
110 | "import time" "" \ | |
111 | "def set_and_detach():" "" \ | |
112 | " gdb.execute(\"set variable dont_exit_just_yet=0\")" "" \ | |
113 | " time.sleep(1)" "" \ | |
114 | " gdb.execute(\"detach\")" "" \ | |
115 | "end" "" | |
116 | ||
117 | # The Python function performs two actions, the first causes the | |
118 | # main thread to exit, while the second detaches from the inferior. | |
119 | # | |
120 | # In both cases the stop arrives while GDB is processing the | |
121 | # detach, however, for remote targets GDB doesn't report the stop, | |
122 | # while for local targets GDB does report the stop. | |
123 | if {![gdb_is_target_remote]} { | |
124 | set stop_re "\\\[Thread.*exited\\\]\r\n" | |
125 | } else { | |
126 | set stop_re "" | |
127 | } | |
128 | gdb_test "python set_and_detach()" \ | |
129 | "${stop_re}\\\[Inferior.*detached\\\]" | |
130 | } | |
131 | ||
132 | foreach_with_prefix spawn_inferior { true false } { | |
133 | if {$spawn_inferior && ![can_spawn_for_attach]} { | |
134 | # If spawning (and attaching too) a separate inferior is not | |
135 | # supported for the current board, then skip this test. | |
136 | continue | |
137 | } | |
138 | ||
139 | run_test $spawn_inferior | |
140 | } |