Unset attach_flag when running a new process

We currently set attach_flag when attaching to a process, so we should
make sure to unset it when forking a new process.  Otherwise attach_flag
would remain set after forking, if the previous process associated with
the inferior was attached to.

gdb/ChangeLog:

	* target.c (target_pre_inferior): Unset attach_flag.

gdb/testsuite/ChangeLog:

	* gdb.base/run-after-attach.exp: New test file.
	* gdb.base/run-after-attach.c: New test file.

gdb/ChangeLog

@@ -1,3 +1,7 @@
+2015-08-26  Patrick Palka  <patrick@parcs.ath.cx>
+
+	* target.c (target_pre_inferior): Unset attach_flag.
+
 2015-08-26  Simon Marchi  <simon.marchi@ericsson.com>
 
 	* gdbarch.sh (append_name): Fix type in XRESIZEVEC.

gdb/target.c

@@ -2138,6 +2138,10 @@ target_pre_inferior (int from_tty)
       target_clear_description ();
     }
 
+  /* attach_flag may be set if the previous process associated with
+     the inferior was attached to.  */
+  current_inferior ()->attach_flag = 0;
+
   agent_capability_invalidate ();
 }
 

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2015-08-26  Patrick Palka  <patrick@parcs.ath.cx>
+
+	* gdb.base/run-after-attach.exp: New test file.
+	* gdb.base/run-after-attach.c: New test file.
+
 2015-08-26  Don Breazeal  <donb@codesourcery.com>
 
 	* gdb.base/foll-exec-2.c: New test program.

gdb/testsuite/gdb.base/run-after-attach.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/run-after-attach.exp

@@ -0,0 +1,62 @@
+# Copyright (C) 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/>.
+
+# Check that forking a process after a previous process was attached to unsets
+# attach_flag.  This is done indirectly by inspecting GDB's quit prompt.
+
+if ![can_spawn_for_attach] {
+    return 0
+}
+
+standard_testfile
+set executable $testfile
+
+if [prepare_for_testing $testfile.exp $executable] {
+    return -1
+}
+
+set test_spawn_id [spawn_wait_for_attach $binfile]
+set test_pid [spawn_id_get_pid $test_spawn_id]
+
+set test "attach to process"
+gdb_test "attach $test_pid" "Attaching to program.*" $test
+
+set test "kill process"
+gdb_test "kill" "" $test \
+    "Kill the program being debugged.*y or n. $" "y"
+
+set test "restart process"
+gdb_test "start" "Starting program.*Temporary breakpoint .*" $test
+
+set test "attempt kill via quit"
+# The quit prompt should warn about killing the process, not about detaching the
+# process, since this process was not attached to.
+set ok 0
+gdb_test_multiple "quit" $test {
+    -re "will be killed.*.y or n. $" {
+	set ok 1
+	send_gdb "n\n"
+	exp_continue
+    }
+    -re "will be detached.*.y or n. $" {
+	send_gdb "n\n"
+	exp_continue
+    }
+    -re "$gdb_prompt $" {
+	gdb_assert $ok $test
+    }
+}
+
+kill_wait_spawned_process $test_spawn_id