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

Pedro Alves
2017-11-17T18:38:22Z

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 that
exposes a latent problem -- 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.

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

gdb/ChangeLog:
yyyy-mm-dd 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.
(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.threads/process-dies-while-detaching.c | 22 +++++++++--
.../gdb.threads/process-dies-while-detaching.exp | 43 +++++++++++++---------
2 files changed, 44 insertions(+), 21 deletions(-)

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..ea8f6e9 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
@@ -87,7 +88,7 @@ proc detach_and_expect_exit {test} {

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
@@ -96,7 +97,7 @@ proc detach_and_expect_exit {test} {
# 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 )" {
+ -re "($inf_output_re)|($gdb_prompt )" {
if {[info exists expect_out(1,string)]} {
verbose -log "saw inferior exit"
set saw_inf_exit 1
@@ -130,15 +131,28 @@ 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.
#
-proc do_detach {multi_process cmd {continue_re ""}} {
+# 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 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 +168,7 @@ 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 +219,7 @@ 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 +254,7 @@ 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 +293,7 @@ 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