Fix invoking "[kill|detach] inferiors" on inferiors that are not running

Invoking either of the above commands on an inferior that's not running
triggers the following assert failure:

  .../binutils-gdb/gdb/thread.c:514: internal-error: any_thread_of_process: Assertion `pid != 0' failed.

The fix is straightforward.  This patch also adds a test to check the
basic functionality of these commands, along with testing this fix in
particular.  Tested on x86_64 Linux.

gdb/ChangeLog:

	* inferior.c (detach_inferior_command): Don't call
	any_thread_of_process when pid is 0.
	(kill_inferior_command): Likewise.

gdb/testsuite/ChangeLog:

	* gdb.base/kill-detach-inferiors-cmd.exp: New test file.
	* gdb.base/kill-detach-inferiors-cmd.c: New test file.

gdb/ChangeLog

@@ -1,3 +1,9 @@
+2015-08-15  Patrick Palka  <patrick@parcs.ath.cx>
+
+	* inferior.c (detach_inferior_command): Don't call
+	any_thread_of_process when pid is 0.
+	(kill_inferior_command): Likewise.
+
 2015-08-14  Doug Evans  <xdje42@gmail.com>
 
 	PR gdb/11833

gdb/inferior.c

@@ -625,6 +625,11 @@ detach_inferior_command (char *args, int from_tty)
 	}
 
       pid = gdb_inferior_id_to_pid (num);
+      if (pid == 0)
+	{
+	  warning (_("Inferior ID %d is not running."), num);
+	  continue;
+	}
 
       tp = any_thread_of_process (pid);
       if (!tp)
@@ -661,6 +666,11 @@ kill_inferior_command (char *args, int from_tty)
 	}
 
       pid = gdb_inferior_id_to_pid (num);
+      if (pid == 0)
+	{
+	  warning (_("Inferior ID %d is not running."), num);
+	  continue;
+	}
 
       tp = any_thread_of_process (pid);
       if (!tp)

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2015-08-15  Patrick Palka  <patrick@parcs.ath.cx>
+
+	* gdb.base/kill-detach-inferiors-cmd.exp: New test file.
+	* gdb.base/kill-detach-inferiors-cmd.c: New test file.
+
 2015-08-14  Doug Evans  <xdje42@gmail.com>
 
 	* gdb.perf/lib/perftest/utils.py (select_file): Kill any existing

gdb/testsuite/gdb.base/kill-detach-inferiors-cmd.c

@@ -0,0 +1,25 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2015 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/>.  */
+
+#include <unistd.h>
+
+int
+main (void)
+{
+  sleep (600);
+  return 0;
+}

gdb/testsuite/gdb.base/kill-detach-inferiors-cmd.exp

@@ -0,0 +1,62 @@
+# This testcase is part of GDB, the GNU debugger.
+#
+# Copyright 2015 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 the basic operation of the "kill inferiors" and "detach inferiors"
+# commands.
+
+if ![can_spawn_for_attach] {
+    return 0
+}
+
+standard_testfile
+set executable $testfile
+
+if [prepare_for_testing $testfile.exp $executable] {
+    return -1
+}
+
+runto_main
+
+# Add another forked inferior process.
+gdb_test "add-inferior" "Added inferior 2" "add inferior 2"
+gdb_test "inferior 2" "Switching to inferior 2.*"
+gdb_test "file $binfile" "Reading symbols from .*done.*" "load binary"
+gdb_test "start" "Temporary breakpoint.*Starting program.*"
+
+# Add an attached inferior process.
+set test_spawn_id [spawn_wait_for_attach $binfile]
+set test_pid [spawn_id_get_pid $test_spawn_id]
+gdb_test "add-inferior" "Added inferior 3" "add inferior 3"
+gdb_test "inferior 3" "Switching to inferior 3.*"
+gdb_test "attach $test_pid" "Attaching to process.*" "attach to pid"
+
+# Kill the first two inferiors, and detach the third.
+gdb_test_no_output "kill inferiors 1 2"
+gdb_test "inferior 1" "Switching to inferior 1.*"
+gdb_test "kill" "The program is not being run.*"
+gdb_test "detach inferiors 3" "Detaching from program.*process $test_pid.*"
+
+# No inferiors should be running anymore.
+gdb_test "kill inferiors 1 2 3" \
+	 "ID 1 is not running.*ID 2 is not running.*ID 3 is not running.*"
+gdb_test "detach inferiors 1 2 3" \
+	 "ID 1 is not running.*ID 2 is not running.*ID 3 is not running.*"
+
+gdb_test "kill inferiors 10" \
+	 "ID 10 not known.*"
+
+kill_wait_spawned_process $test_spawn_id