Add test that exercises the inferior being killed while stopped under GDB

This exercises the case of the inferior disappearing while GDB is
debugging it, such as something doing "kill -9 PID" while the program
is stopped under GDB or GDBserver.  This triggered a set of internal
errors, fixed by previous patches.

gdb/testsuite/ChangeLog:
2015-07-14  Pedro Alves  <palves@redhat.com>

	* gdb.base/killed-outside.exp: New file.
	* gdb.base/killed-outside.c: New file.

3 files changed, 169 insertions, 0 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 4f94360..47c1e9b 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2015-07-14  Pedro Alves  <palves@redhat.com>
+
+	* gdb.base/killed-outside.exp: New file.
+	* gdb.base/killed-outside.c: New file.
+
 2015-07-10  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
 	* gdb.asm/asm-source.exp (f at main): Stop at gdbasm_enter.
diff --git a/gdb/testsuite/gdb.base/killed-outside.c b/gdb/testsuite/gdb.base/killed-outside.c
new file mode 100644
index 0000000..f0e9eda
--- /dev/null
+++ b/gdb/testsuite/gdb.base/killed-outside.c
@@ -0,0 +1,34 @@
+/* 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 <sys/types.h>
+#include <unistd.h>
+
+pid_t pid;
+
+static void
+done (void)
+{
+}
+
+int
+main (int argc, char **argv)
+{
+  pid = getpid ();
+  done ();
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.base/killed-outside.exp b/gdb/testsuite/gdb.base/killed-outside.exp
new file mode 100644
index 0000000..1e8c0d3
--- /dev/null
+++ b/gdb/testsuite/gdb.base/killed-outside.exp
@@ -0,0 +1,130 @@
+# 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 that GDB doesn't get badly wedged if the inferior is killed
+# from outside GDB (with SIGKILL) while the program is stopped.
+
+standard_testfile
+
+# Get the value of variable VAR in the inferior.  MSG is used as the
+# test message.
+
+proc get_value {var msg} {
+    global expect_out
+    global gdb_prompt
+    global decimal
+
+    set value -1
+    gdb_test_multiple "print $var" "$msg" {
+	-re ".*= ($decimal).*\r\n$gdb_prompt $" {
+	    set value $expect_out(1,string)
+	    pass "$msg"
+        }
+    }
+    return ${value}
+}
+
+# Runs the program until a breakpoint, deletes all breakpoints, and
+# then kills the inferior from _outside_ GDB, with SIGKILL.  Runs CMDS
+# afterwards, to make sure GDB copes with the inferior disappearing,
+# and then quits GDB.
+
+proc test {cmds_after_kill} {
+    global binfile
+    global gdb_prompt
+    global decimal
+
+    clean_restart ${binfile}
+
+    if ![runto done] {
+	return
+    }
+
+    # So that "continue" doesn't try a step over, etc.
+    delete_breakpoints
+
+    set testpid [get_value "pid" "get pid of inferior"]
+    if { $testpid == -1 } {
+	return -1
+    }
+
+    remote_exec target "kill -9 ${testpid}"
+
+    # Give it some time to die.
+    sleep 2
+
+    uplevel 1 $cmds_after_kill
+
+    # Make sure we can quit.
+    set msg "quit GDB"
+    gdb_test_multiple "quit" $msg {
+	-re "Quit anyway\\? \\(y or n\\) $" {
+	    send_gdb "y\n"
+	    exp_continue
+	}
+	eof {
+	    pass $msg
+	}
+    }
+}
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile $options] == -1} {
+    return -1
+}
+
+# The actual output GDB prints in response to commands after the
+# inferior is gone isn't very well defined, and will depend on target.
+# What we're trying to make sure is that GDB doesn't internal error or
+# get wedged.
+
+# Try simply continuing.
+with_test_prefix "continue" {
+    test {
+	# Try stepping the program.  Stepping may need to read/write
+	# registers, unlike continue.
+	gdb_test "continue" ".*"
+
+	# Try listing threads afterwards.  It's probably what the user
+	# will do after an error.
+	gdb_test "info threads" ".*"
+    }
+}
+
+# Try stepping the program.  Stepping may go through diferent code
+# paths in the target backends.
+with_test_prefix "stepi" {
+    test {
+	gdb_test "si" ".*"
+	gdb_test "info threads" ".*"
+    }
+}
+
+# Try fetching registers explicitly, which should cover the error many
+# other commands would trigger.
+with_test_prefix "registers" {
+    test {
+	gdb_test "flushregs" ".*"
+	gdb_test "info threads" ".*"
+    }
+}
+
+# Try only listing threads explicitly, first thing, which is another
+# operation GDB may or not decide to do itself and is likely to be
+# what a user would try after error too.
+with_test_prefix "info threads" {
+    test {
+	gdb_test "info threads" ".*"
+    }
+}