Re: [PATCH] Fix gdb.threads/process-dies-while-detaching.exp

Pedro Alves
2017-12-03T15:34:02Z

On 12/03/2017 03:24 PM, Pedro Alves wrote:

> I'm squashing in the patch below.
>

And here's the resulting patch that I pushed in.

From f0fb2488c93c00fa1436a4813a375faa00a94de5 Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Sun, 3 Dec 2017 15:32:08 +0000
Subject: [PATCH] Fix gdb.threads/process-dies-while-detaching.exp

I noticed [1] a test bug in gdb.threads/process-dies-while-detaching.exp.
Simplified, the test code in question looks somewhat like this:

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

proc detach_and_expect_exit {test} {

gdb_test_multiple "detach" $test ....

set saw_prompt 0
set saw_inf_exit 0
while { !$saw_prompt && !$saw_inf_exit } {
gdb_test_multiple "" $test {
-re "exited, status=0" {
set saw_inf_exit 1
}
-re "$gdb_prompt " {
set saw_prompt 1
}
}
}

pass $test
}
~~~

The bug is in the while loop's condition. We want to make sure we see
both the inferior output and the prompt, so the loop's test should be:

- while { !$saw_prompt && !$saw_inf_exit } {
+ while { !$saw_prompt || !$saw_inf_exit } {

If we just fix that, the test starts failing though, because it
exposes a couple latent problems:

- When called from test_detach_killed_outside, the parent doesn't
print "exited, status=0", because in that case the child dies with a
signal, and so detach_and_expect_exit times out.

Fix it by making the parent print "signaled, sig=9" in that case,
and have the .exp expect it.

- When testing against --target_board=native-gdbserver, sometimes we'd
get this:

ERROR: Process no longer exists
ERROR: : spawn id exp9 not open
while executing
"expect {
-i exp8 -timeout 220
-i $server_spawn_id
eof {
pass $test
wait -i $server_spawn_id
unset server_spawn_id
}
timeout {
..."
("uplevel" body line 1)
invoked from within
"uplevel $body" NONE : spawn id exp9 not open

The problem is that:

- inferior_spawn_id and server_spawn_id are the same when testing
with gdbserver.
- gdbserver exits after "detach", so we get an eof for
$inferior_spawn_id in the loop in detach_and_expect_exit.
That's the first "ERROR: Process no longer exists".
- and then when we reach test_server_exit, server_spawn_id
is already closed (because server_spawn_id==inferior_spawn_id).

To handle this, make the loop in detach_and_expect_exit use an
indirect spawn id list and remove $inferior_spawn_id from the list
as soon as we got the inferior output we're expecting, so that the
"eof" is left unprocessed until we reach test_server_exit.

[1] I changed GDB in a way that should have made the test fail, but it
didn't.

gdb/testsuite/ChangeLog:
2017-12-03 Pedro Alves <palves@redhat.com>

* gdb.threads/process-dies-while-detaching.c: Include <errno.h>
and <string.h>.
(parent_function): Print distinct messages when waitpid fails, or
the child exits with a signal, or the child exits for an unhandled
reason.
* gdb.threads/process-dies-while-detaching.exp
(detach_and_expect_exit): New 'inf_output_re' parameter and use
it. Wait for both inferior output and GDB's prompt. Use an
indirect spawn id list.
(do_detach): New parameter 'child_exit'. Use it to compute
expected inferior output.
(test_detach, test_detach_watch, test_detach_killed_outside):
Adjust to pass down the expected child exit kind.
---
gdb/testsuite/ChangeLog | 16 +++++++
.../gdb.threads/process-dies-while-detaching.c | 22 +++++++--
.../gdb.threads/process-dies-while-detaching.exp | 55
+++++++++++++++-------
3 files changed, 71 insertions(+), 22 deletions(-)

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 779fd0a..fa096b3 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,19 @@
+2017-12-03 Pedro Alves <palves@redhat.com>
+
+ * gdb.threads/process-dies-while-detaching.c: Include <errno.h>
+ and <string.h>.
+ (parent_function): Print distinct messages when waitpid fails, or
+ the child exits with a signal, or the child exits for an unhandled
+ reason.
+ * gdb.threads/process-dies-while-detaching.exp
+ (detach_and_expect_exit): New 'inf_output_re' parameter and use
+ it. Wait for both inferior output and GDB's prompt. Use an
+ indirect spawn id list.
+ (do_detach): New parameter 'child_exit'. Use it to compute
+ expected inferior output.
+ (test_detach, test_detach_watch, test_detach_killed_outside):
+ Adjust to pass down the expected child exit kind.
+
2017-12-01 Joel Brobecker <brobecker@adacore.com>
Sergio Durigan Junior <sergiodj@redhat.com>
Pedro Alves <palves@redhat.com>
diff --git a/gdb/testsuite/gdb.threads/process-dies-while-detaching.c
b/gdb/testsuite/gdb.threads/process-dies-while-detaching.c
index eecaaed..4ba50d4 100644
--- a/gdb/testsuite/gdb.threads/process-dies-while-detaching.c
+++ b/gdb/testsuite/gdb.threads/process-dies-while-detaching.c
@@ -22,6 +22,8 @@
#include <sys/types.h>
#include <sys/wait.h>
#include <assert.h>
+#include <errno.h>
+#include <string.h>

/* This barrier ensures we only reach the initial breakpoint after all
threads have started. */
@@ -78,15 +80,27 @@ parent_function (pid_t child)
alarm (300);

ret = waitpid (child, &status, 0);
+
if (ret == -1)
- exit (1);
- else if (!WIFEXITED (status))
- exit (2);
- else
+ {
+ printf ("waitpid, errno=%d (%s)\n", errno, strerror (errno));
+ exit (1);
+ }
+ else if (WIFEXITED (status))
{
printf ("exited, status=%d\n", WEXITSTATUS (status));
exit (0);
}
+ else if (WIFSIGNALED (status))
+ {
+ printf ("signaled, sig=%d\n", WTERMSIG (status));
+ exit (2);
+ }
+ else
+ {
+ printf ("unexpected, status=%x\n", status);
+ exit (3);
+ }
}

#endif
diff --git a/gdb/testsuite/gdb.threads/process-dies-while-detaching.exp
b/gdb/testsuite/gdb.threads/process-dies-while-detaching.exp
index 4cba80c..910e786 100644
--- a/gdb/testsuite/gdb.threads/process-dies-while-detaching.exp
+++ b/gdb/testsuite/gdb.threads/process-dies-while-detaching.exp
@@ -72,9 +72,10 @@ proc return_if_fail { result } {
}

# Detach from a process, and ensure that it exits after detaching.
-# This relies on inferior I/O.
+# This relies on inferior I/O. INF_OUTPUT_RE is the pattern that
+# matches the expected inferior output.

-proc detach_and_expect_exit {test} {
+proc detach_and_expect_exit {inf_output_re test} {
global decimal
global gdb_spawn_id
global inferior_spawn_id
@@ -85,9 +86,17 @@ proc detach_and_expect_exit {test} {
}
}]

+ # Use an indirect spawn id list, and remove inferior spawn id from
+ # the expected output as soon as it matches, so that if
+ # $inf_inferior_spawn_id is $server_spawn_id and we're testing in
+ # "target remote" mode, the eof caused by gdbserver exiting is
+ # left for the caller to handle.
+ global daee_spawn_id_list
+ set daee_spawn_id_list "$inferior_spawn_id $gdb_spawn_id"
+
set saw_prompt 0
set saw_inf_exit 0
- while { !$saw_prompt && ! $saw_inf_exit } {
+ while { !$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
@@ -95,14 +104,16 @@ proc detach_and_expect_exit {test} {
# 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 )" {
+ -i daee_spawn_id_list
+ -re "($inf_output_re)|($gdb_prompt )" {
if {[info exists expect_out(1,string)]} {
verbose -log "saw inferior exit"
set saw_inf_exit 1
+ set daee_spawn_id_list "$gdb_spawn_id"
} elseif {[info exists expect_out(2,string)]} {
verbose -log "saw prompt"
set saw_prompt 1
+ set daee_spawn_id_list "$inferior_spawn_id"
}
array unset expect_out
}
@@ -130,15 +141,28 @@ proc continue_to_exit_bp {} {
#
# 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.
+# exit.
+#
+# CHILD_EXIT indicates how is the child expected to exit. Can be
+# either "normal" for normal exit, or "signal" for killed with signal
+# SIGKILL.
#
-proc do_detach {multi_process cmd {continue_re ""}} {
+proc do_detach {multi_process cmd child_exit} {
global decimal
global server_spawn_id

- if {$continue_re == ""} {
+ if {$child_exit == "normal"} {
set continue_re "exited normally.*"
+ set inf_output_re "exited, status=0"
+ } elseif {$child_exit == "signal"} {
+ if {$multi_process} {
+ set continue_re "exited with code 02.*"
+ } else {
+ set continue_re "terminated with signal SIGKILL.*"
+ }
+ set inf_output_re "signaled, sig=9"
+ } else {
+ error "unhandled \$child_exit: $child_exit"
}

set is_remote [expr {[target_info exists gdb_protocol]
@@ -154,7 +178,7 @@ proc do_detach {multi_process cmd {continue_re ""}} {
if {$cmd == "detach"} {
# Make sure that detach works and that the parent process
# exits cleanly.
- detach_and_expect_exit "detach parent"
+ detach_and_expect_exit $inf_output_re "detach parent"
} elseif {$cmd == "continue"} {
# Make sure that continuing works and that the parent process
# exits cleanly.
@@ -205,7 +229,7 @@ proc test_detach {multi_process cmd} {
# Run to _exit in the child.
continue_to_exit_bp

- do_detach $multi_process $cmd
+ do_detach $multi_process $cmd "normal"
}
}

@@ -240,7 +264,7 @@ proc test_detach_watch {multi_process cmd} {
# thread individually).
continue_to_exit_bp

- do_detach $multi_process $cmd
+ do_detach $multi_process $cmd "normal"
}
}

@@ -279,12 +303,7 @@ proc test_detach_killed_outside {multi_process cmd} {
# 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
+ do_detach $multi_process $cmd "signal"
}
}

--
2.5.5