Put GDB's terminal settings into effect when paginating

When the target is resumed in the foreground, we put the inferior's
terminal settings into effect, and remove stdin from the event loop.
When the target stops, we put GDB's terminal settings into effect
again, and re-register stdin in the event loop, ready for user input.
The former is done by target_terminal_inferior, and the latter by
target_terminal_ours.

There's an intermediate -- target_terminal_ours_for_output -- that is
called when printing output related to target events, and we don't
know yet whether we'll stop the program.  That puts our terminal
settings into effect, enough to get proper results from our output,
but leaves input wired into the inferior.

If such output paginates, then we need the full target_terminal_ours
in order for the user to be able to provide input to answer the
pagination query.

The test in this commit hangs in async-capable targets without the fix
(as the user/test can't answer the pagination query).  It doesn't hang
on sync targets because on those we don't unregister stdin from the
event loop while the target is running (because we block in
target_wait instead of in the event loop in that case).

gdb/
2014-07-14  Pedro Alves  <palves@redhat.com>

	* utils.c (prompt_for_continue): Call target_terminal_ours.

gdb/testsuite/
2014-07-14  Pedro Alves  <palves@redhat.com>

	* gdb.base/paginate-after-ctrl-c-running.c: New file.
 	* gdb.base/paginate-after-ctrl-c-running.exp: New file.

gdb/testsuite/gdb.base/paginate-after-ctrl-c-running.c

@@ -0,0 +1,25 @@
+/* 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
+main (void)
+{
+  sleep (10);
+  return 0; /* after sleep */
+}

gdb/testsuite/gdb.base/paginate-after-ctrl-c-running.exp

@@ -0,0 +1,87 @@
+# Copyright (C) 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/>.
+
+standard_testfile
+
+if {[build_executable "failed to prepare" $testfile $srcfile debug] == -1} {
+    return -1
+}
+
+# Send a ctrl-c while the target is running and the next output causes
+# a pagination prompt.
+
+proc test_ctrlc_while_target_running_paginates {} {
+    global binfile srcfile
+    global gdb_prompt pagination_prompt
+
+    set testline [gdb_get_line_number "after sleep"]
+
+    with_test_prefix "ctrlc target running" {
+	clean_restart $binfile
+
+	if ![runto_main] then {
+	    fail "Can't run to main"
+	    return 0
+	}
+
+	gdb_test "b $srcfile:$testline" \
+	    "Breakpoint .*$srcfile, line $testline.*" \
+	    "set breakpoint"
+
+	gdb_test_no_output "set height 2"
+
+	# Wait for the "Continuing" line, indicating the program is
+	# running.
+	set test "continue"
+	gdb_test_multiple $test $test {
+	    -re "Continuing" {
+		pass $test
+	    }
+	}
+
+	# The program sleeps 10 seconds.  Wait just a bit and send a
+	# ctrl-c.
+	sleep 2
+	send_gdb "\003"
+
+	# GDB now intercepts the SIGINT and tries to let the user know
+	# about the spurious signal, but that paginates.  Make sure
+	# the user can respond to the pagination query.
+	set test "got prompt"
+	set saw_pagination_prompt 0
+	gdb_test_multiple "" $test {
+	    -re "$pagination_prompt$" {
+		set saw_pagination_prompt 1
+		send_gdb "\n"
+		exp_continue
+	    }
+	    -re "$gdb_prompt $" {
+		gdb_assert $saw_pagination_prompt $test
+	    }
+	    -notransfer -re "<return>" {
+		# Otherwise gdb_test_multiple considers this an error.
+		exp_continue
+	    }
+	}
+
+	# Confirm GDB can still process input.
+	gdb_test "p 1" " = 1" "GDB accepts further input"
+
+	# In case the board file wants to send further commands.
+	gdb_test_no_output "set height unlimited"
+    }
+}
+
+test_ctrlc_while_target_running_paginates

gdb/utils.c

@@ -1877,6 +1877,10 @@ prompt_for_continue (void)
 
   immediate_quit++;
   QUIT;
+
+  /* We'll need to handle input.  */
+  target_terminal_ours ();
+
   /* On a real operating system, the user can quit with SIGINT.
      But not on GO32.