Test breakpoint commands w/ "continue" + Ctrl-C

This adds the testcase that exposed the multiple problems with Ctrl-C
handling fixed by the previous patches, when run against both native
and gdbserver GNU/Linux.

gdb/ChangeLog:
2017-11-16  Pedro Alves  <palves@redhat.com>

	* gdb.base/bp-cmds-continue-ctrl-c.c: New file.
	* gdb.base/bp-cmds-continue-ctrl-c.exp: New file.

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2017-11-16  Pedro Alves  <palves@redhat.com>
+
+	* gdb.base/bp-cmds-continue-ctrl-c.c: New file.
+	* gdb.base/bp-cmds-continue-ctrl-c.exp: New file.
+
 2017-11-16  Pedro Alves  <palves@redhat.com>
 
 	* gdb.rust/modules.exp: Skip tests that rely on inferior I/O if

gdb/testsuite/gdb.base/bp-cmds-continue-ctrl-c.c

@@ -0,0 +1,35 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2017 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>
+
+static void
+foo (void)
+{
+  usleep (100);
+}
+
+int
+main ()
+{
+  alarm (60);
+
+  while (1)
+    foo ();
+
+  return 0;
+}

gdb/testsuite/gdb.base/bp-cmds-continue-ctrl-c.exp

@@ -0,0 +1,136 @@
+# Copyright 2017 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/>.
+
+# Set a breakpoint with a "continue" command attached, let the
+# inferior hit the breakpoint continuously.  Check that we can use ^C
+# to interrupt the command, and that if ^C is pressed while GDB has
+# the terminal (between the stop and the re-resume), the resulting
+# "Quit" doesn't mess up the debug session.
+
+if [target_info exists gdb,nosignals] {
+    verbose "Skipping because of nosignals."
+    continue
+}
+
+# This test requires sending ^C to interrupt the running target.
+if [target_info exists gdb,nointerrupts] {
+    verbose "Skipping because of nointerrupts."
+    return
+}
+
+standard_testfile
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile debug]} {
+    return -1
+}
+
+# See intro.
+
+proc do_test {} {
+    global srcfile binfile
+    global gdb_prompt
+
+    gdb_test "break foo" "Breakpoint .*" "set breakpoint"
+
+    gdb_test \
+	[multi_line_input \
+	     {commands} \
+	     {  c} \
+	     {end}] \
+	"" "commands"
+
+    set test "stop with control-c"
+
+    for {set iter 0} {$iter < 20} {incr iter} {
+
+	# Useful for debugging.
+	#send_user "iter: $iter\n"
+
+	# Consume one breakpoint hit (at least), to make sure that the
+	# continue actually continues between attempts, as opposed to
+	# "c" not actually resuming and then Ctrl-C managing to
+	# interrupt anyway.
+	if {[gdb_test_multiple "continue" "$test (continue)" {
+	    -re "Continuing.*Breakpoint \[^\r\n\]*\r\n" {
+	    }
+	}] != 0} {
+	    return
+	}
+
+	set internal_pass "IPASS: $test (iter $iter)"
+
+	# Breakpoint commands run after the target is considered
+	# stopped, and thus run with GDB owning the terminal.  That
+	# means that it is expected that a Ctrl-C that arrives between
+	#  - GDB reporting the breakpoint hit, and,
+	#  - the breakpoint command continuing the target
+	# results in a Quit.
+
+	after 200 {send_gdb "\003"}
+	if {[gdb_test_multiple "" "$test (unexpected)" {
+	    -re "Program terminated with signal SIGALRM.*\r\n$gdb_prompt $" {
+		fail "$test (SIGALRM)"
+		return
+	    }
+	    -re "Program received signal SIGINT.*\r\n$gdb_prompt $" {
+		send_log "$internal_pass (SIGINT)\n"
+	    }
+	    -re "Quit\r\n$gdb_prompt $" {
+		send_log "$internal_pass (Quit)\n"
+	    }
+	    -re "Quit\r\n\r\nCommand aborted.\r\n$gdb_prompt $" {
+		send_log "$internal_pass (Command aborted)\n"
+	    }
+	    -re "Breakpoint \[^\r\n\]*$srcfile" {
+		exp_continue
+	    }
+	}] != 0} {
+	    break
+	}
+    }
+
+    gdb_assert {$iter == 20} "stop with control-c"
+}
+
+# With native debugging and "run" (with job control), if the inferior
+# is running, the Ctrl-C reaches the inferior directly, not GDB.  With
+# native debugging and "attach", or with remote debugging, the Ctrl-C
+# reaches GDB first.  So for completeness, try both "run" and
+# "attach".
+
+with_test_prefix "run" {
+    clean_restart $binfile
+
+    if {![runto_main]} {
+	return -1
+    }
+
+    do_test
+}
+
+with_test_prefix "attach" {
+    if {[can_spawn_for_attach]} {
+	clean_restart $binfile
+
+	set test_spawn_id [spawn_wait_for_attach $binfile]
+	set testpid [spawn_id_get_pid $test_spawn_id]
+
+	gdb_test "attach $testpid" "Attaching to.*process $testpid.*" "attach"
+
+	do_test
+
+	kill_wait_spawned_process $test_spawn_id
+    }
+}