PR gdb/17471: Repeating a background command makes it foreground

When we repeat a command, by just pressing <ret>, the input from the
previous command is reused for the new command invocation.

When an execution command strips the "&" out of its incoming argument
string, to detect background execution, we poke a '\0' directly to the
incoming argument string.

Combine both, and a repeat of a background command loses the "&".

This is actually only visible if args other than "&" are specified
(e.g., "c 1&" or "next 2&" or "c -a&"), as in the special case of "&"
alone (e.g. "c&") doesn't actually clobber the incoming string.

Fix this by making strip_bg_char return a new string instead of poking
a hole in the input string.

New test included.

Tested on x86_64 Fedora 20, native and gdbserver.

gdb/
2014-10-17  Pedro Alves  <palves@redhat.com>

	PR gdb/17471
	* infcmd.c (strip_bg_char): Change prototype and rewrite.  Now
	returns a copy of the input.
	(run_command_1, continue_command, step_1, jump_command)
	(signal_command, until_command, advance_command, finish_command)
	(attach_command): Adjust and install a cleanup to free the
	stripped args.

gdb/testsuite/
2014-10-17  Pedro Alves  <palves@redhat.com>

	PR gdb/17471
	* gdb.base/bg-execution-repeat.c: New file.
	* gdb.base/bg-execution-repeat.exp: New file.

1 files changed, 33 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.base/bg-execution-repeat.c b/gdb/testsuite/gdb.base/bg-execution-repeat.c
new file mode 100644
index 0000000..26ab997
--- /dev/null
+++ b/gdb/testsuite/gdb.base/bg-execution-repeat.c
@@ -0,0 +1,33 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2014 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
+foo (void)
+{
+  return 0; /* set break here */
+}
+
+int
+main (void)
+{
+  foo ();
+  sleep (5);
+  foo ();
+  return 0;
+}