Testcase for attaching in non-stop mode

This adds a testcase exercising attaching to a multi-threaded process,
in all combinations of:

  - set non-stop on/off
  - maint target non-stop off/on
  - "attach" vs "attach &"

This exercises the bugs fixed in the two previous patches.

gdb/testsuite/ChangeLog:

	* gdb.threads/attach-non-stop.c: New file.
	* gdb.threads/attach-non-stop.exp: New file.

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2021-02-03  Pedro Alves  <pedro@palves.net>
+
+	* gdb.threads/attach-non-stop.c: New file.
+	* gdb.threads/attach-non-stop.exp: New file.
+
 2021-02-02  Lancelot SIX  <lsix@lancelotsix.com>
 
 	* gdb.base/inferior-noarg.c: New test.

gdb/testsuite/gdb.threads/attach-non-stop.c

@@ -0,0 +1,58 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2021 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#define _GNU_SOURCE
+#include <assert.h>
+#include <pthread.h>
+#include <unistd.h>
+
+/* Number of threads we'll create.  */
+static const int n_threads = 10;
+
+/* Entry point for threads.  Loops forever.  */
+
+void *
+thread_func (void *arg)
+{
+  while (1)
+    sleep (1);
+
+  return NULL;
+}
+
+int
+main (int argc, char **argv)
+{
+  int i;
+
+  alarm (30);
+
+  /* Spawn the test threads.  */
+  for (i = 0; i < n_threads; ++i)
+    {
+      pthread_t child;
+      int rc;
+
+      rc = pthread_create (&child, NULL, thread_func, NULL);
+      assert (rc == 0);
+    }
+
+  while (1)
+    sleep (1);
+
+  return 0;
+}

gdb/testsuite/gdb.threads/attach-non-stop.exp

@@ -0,0 +1,148 @@
+# Copyright 2021 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test attaching to a multi-threaded process, in all combinations of:
+#
+#  - set non-stop on/off
+#  - maint target non-stop off/on
+#  - "attach" vs "attach &"
+
+if {![can_spawn_for_attach]} {
+    return 0
+}
+
+standard_testfile
+
+# The test proper.  See description above.
+
+proc test {target_non_stop non_stop cmd} {
+    global binfile srcfile
+    global gdb_prompt
+    global decimal
+    global GDBFLAGS
+
+    # Number of threads started by the program.
+    set n_threads 10
+
+    save_vars { GDBFLAGS } {
+	append GDBFLAGS " -ex \"maint set target-non-stop $target_non_stop\""
+	append GDBFLAGS " -ex \"set non-stop $non_stop\""
+	clean_restart $binfile
+    }
+
+    set test_spawn_id [spawn_wait_for_attach $binfile]
+    set testpid [spawn_id_get_pid $test_spawn_id]
+
+    set attached 0
+    set test "attach"
+    set any "\[^\r\n\]*"
+
+    if {$cmd == "attach"} {
+	gdb_test_multiple "attach $testpid" $test {
+	    -re "Attaching to program:${any}process $testpid\r\n.*$gdb_prompt " {
+		pass $test
+		set attached 1
+	    }
+	}
+
+	if {!$attached} {
+	    kill_wait_spawned_process $test_spawn_id
+	    return
+	}
+
+	if {$non_stop} {
+	    # In non-stop, we will see one stop per thread after
+	    # the prompt.
+	    set stops 0
+	    set test "seen all stops"
+	    for {set thread 1} { $thread <= $n_threads } { incr thread } {
+		gdb_test_multiple "" $test {
+		    -re "Thread $::decimal ${any} stopped" {
+			incr stops
+		    }
+		}
+	    }
+
+	    # If we haven't seen all stops, then the gdb_test_multiple
+	    # in the loop above will have already issued a FAIL.
+	    if {$stops == $n_threads} {
+		pass $test
+	    }
+	}
+
+	gdb_test_multiple "info threads" "" {
+	    -re "\\(running\\).*$gdb_prompt $" {
+		fail $gdb_test_name
+	    }
+	    -re "$gdb_prompt $" {
+		pass $gdb_test_name
+	    }
+	}
+    } else {
+	gdb_test_multiple "attach $testpid &" $test {
+	    -re "Attaching to program:${any}process $testpid\r\n.*$gdb_prompt " {
+		pass $test
+		set attached 1
+	    }
+	}
+
+	if {!$attached} {
+	    kill_wait_spawned_process $test_spawn_id
+	    return
+	}
+
+	set running_count 0
+	gdb_test_multiple "info threads" "all threads running" {
+	    -re "\\(running\\)" {
+		incr running_count
+		exp_continue
+	    }
+	    -re "Cannot execute this command while the target is running.*$gdb_prompt $" {
+		# Testing against a remote server that doesn't do
+		# non-stop mode.  Explicitly interrupt.  This doesn't
+		# test the same code paths in GDB, but it's still
+		# something.
+		gdb_test_multiple "interrupt" "" {
+		    -re "$gdb_prompt " {
+			gdb_test_multiple "" $gdb_test_name {
+			    -re "received signal SIGINT, Interrupt" {
+				pass $gdb_test_name
+			    }
+			}
+		    }
+		}
+	    }
+	    -re "$gdb_prompt $" {
+		gdb_assert {$running_count == ($n_threads + 1)} $gdb_test_name
+	    }
+	}
+    }
+
+    gdb_test "detach" "Detaching from.*"
+
+    kill_wait_spawned_process $test_spawn_id
+}
+
+if {[build_executable "failed to prepare" $testfile $srcfile {debug pthreads}] == -1} {
+    return -1
+}
+
+foreach_with_prefix target-non-stop {"off" "on"} {
+    foreach_with_prefix non-stop {"off" "on"} {
+	foreach_with_prefix cmd {"attach" "attach&"} {
+	    test ${target-non-stop} ${non-stop} ${cmd}
+	}
+    }
+}