[PATCH 2/2] gdb.threads/attach-into-signal.exp: don't rely on linux native target's internal debug output

[Pedro Alves <palves at redhat dot com>]

This test relies on Linux native target's debug output ("set debug
lin-lwp 1"), which obviously can't work when testing against GDBserver
(with the extended-remote board).

This patch makes the test more generic, using only regular GDB
functionality, avoiding relying on internal debug output.

The test runs twice, with two variants: once non-threaded, and once
threaded.  SIGLARM defaults to noprint, but if we set it to print,
then for the non-threaded case, when we attach and find the main
thread stopping with SIGLARM, we'll see "Program received signal
SIGLARM".  For the threaded case, the signal is seen on the non main
thread, so we won't see "Program received signal SIGLARM".  Instead,
we check the second thread's siginfo.si_signo.  We can't use this
method for the non-threaded case too, because the Linux native target
when attaching finds another signal other than SIGSTOP, puts that
other signal pending, and waits for the SIGSTOP, so siginfo.si_signo
will always show SIGSTOP.

With this, GDBserver fails the test, because it doesn't really support
what's being tested here.  Namely, it doesn't deliver the SIGALRM back
to the inferior on detach (so the program ends up on the abort()
call).  I have a fix for that, but it needs a bit more cleaning up.

Jan, is this okay with you?

2012-02-17  Pedro Alves  <palves@redhat.com>

	* gdb.threads/attach-into-signal.exp (corefunc): Don't enable
	lin-lwp output.  Set SIGALRM to stop.  Adjust tests to not rely on
	gdb's internal debug output.  For the non-threaded case, look for
	"Program received signal SIGLARM", for the threaded case, peek at
	the thread's siginfo.
---
 gdb/testsuite/gdb.threads/attach-into-signal.exp |   57 ++++++++++++++++------
 1 files changed, 41 insertions(+), 16 deletions(-)

diff --git a/gdb/testsuite/gdb.threads/attach-into-signal.exp b/gdb/testsuite/gdb.threads/attach-into-signal.exp
index bf4b8a0..c839339 100644
--- a/gdb/testsuite/gdb.threads/attach-into-signal.exp
+++ b/gdb/testsuite/gdb.threads/attach-into-signal.exp
@@ -47,7 +47,6 @@ proc corefunc { threadtype executable } {
     lappend pf_prefix "$threadtype:"
 
     clean_restart ${executable}
-    gdb_test_no_output "set debug lin-lwp 1" ""
 
     set binfile ${objdir}/${subdir}/${executable}
     set escapedbinfile [string_to_regexp ${objdir}/${subdir}/${executable}]
@@ -57,6 +56,8 @@ proc corefunc { threadtype executable } {
 	return -1
     }
 
+    gdb_test "handle SIGALRM stop print pass" "Yes.*Yes.*Yes.*"
+
     # Start the program running and then wait for a bit, to be sure
     # that it can be attached to.
     # Statistically there is a better chance without giving process a nice.
@@ -99,27 +100,51 @@ proc corefunc { threadtype executable } {
 	# Main test:
 	set test "attach (pass $passes), pending signal catch"
 	if {[gdb_test_multiple "attach $testpid" $test {
-	    -re "Attaching to program.*`?$escapedbinfile'?, process $testpid.*Received Alarm clock.*$gdb_prompt $" {
+	    -re "Attaching to program.*`?$escapedbinfile'?, process $testpid.*Program received signal SIGALRM.*$gdb_prompt $" {
 		# nonthreaded:
 		pass $test
 		verbose -log "$test succeeded on the attempt # $attempt of $attempts"
 		set passes [expr $passes + 1]
 	    }
 	    -re "Attaching to program.*`?$escapedbinfile'?, process $testpid.*$gdb_prompt $" {
-		# nonthreaded:
-		# We just lack the luck, we should try it again.
-		set attempt [expr $attempt + 1]
-	    }
-	    -re "Attaching to process $testpid.*Received Alarm clock.*$gdb_prompt $" {
-		# threaded:
-		pass $test
-		verbose -log "$test succeeded on the attempt # $attempt of $attempts"
-		set passes [expr $passes + 1]
-	    }
-	    -re "Attaching to process $testpid.*$gdb_prompt $" {
-		# threaded:
-		# We just lack the luck, we should try it again.
-		set attempt [expr $attempt - 1]
+		set ok 0
+
+		if { $threadtype == "threaded" } {
+		    # In the threaded case, the signal is left pending
+		    # on the second thread.  Check for that by peeking
+		    # at the thread's siginfo.  SIGALRM is 14, SIGSTOP
+		    # is 19.
+
+		    # With remote targets, we need to pull the thread
+		    # list explicitly before GDB even knows about
+		    # thread 2.
+		    set test2 "pull thread list"
+		    gdb_test_multiple "info threads" $test2 {
+			-re "\r\n$gdb_prompt $" {
+			}
+		    }
+
+		    set test2 "thread apply 2 print \$_siginfo.si_signo"
+		    gdb_test_multiple $test2 $test2 {
+			-re " = 14\r\n$gdb_prompt $" {
+			    set ok 1
+			}
+			-re " = 19\r\n$gdb_prompt $" {
+			}
+		    }
+		} else {
+		    # In the nonthreaded case, GDB should tell the
+		    # user about having seen a signal.
+		}
+
+		if { $ok == 0} {
+		    # We just lack the luck, we should try it again.
+		    set attempt [expr $attempt + 1]
+		} else {
+		    pass $test
+		    verbose -log "$test succeeded on the attempt # $attempt of $attempts"
+		    set passes [expr $passes + 1]
+		}
 	    }
 	}] != 0 } {
 	    break