[binutils-gdb] GDBserver: Fix ignored Ctrl-C after reconnection

[Pedro Alves <palves at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=e849ea896bcdc3da8caff02eb6dc91dc85dd8a7e

commit e849ea896bcdc3da8caff02eb6dc91dc85dd8a7e
Author: Pedro Alves <palves@redhat.com>
Date:   Thu Nov 16 14:58:51 2017 +0000

    GDBserver: Fix ignored Ctrl-C after reconnection
    
    This fixes the issue reported by Dmitry Antipov <dantipov@nvidia.com>
    here:
      https://sourceware.org/ml/gdb/2017-10/msg00048.html
    
    The problem is that GDBserver stops listening to Ctrl-C/interrupt
    requests if you disconnect and reconnect back.
    
    Dmitry wrote:
    
    ~~~
    Currently gdbserver installs SIGIO handler just once, in
    initialize_async_io() called from captured_main(), and this handler is
    removed when remote_desc is closed in remote_close().  Next, when a
    new instance of remote_desc is fetched from accept() and has '\003'
    arrived, input_interrupt() is never called because it is not
    registered as SIGIO handler.
    ~~~
    
    The fix here is not remove the SIGIO handler in the first place, thus
    going back to the original before-first-connection state.
    
    (I haven't gone back to try it, but I think this was a regression
    caused by commit 8b2073398477 ("[GDBserver] Block and unblock SIGIO"),
    which was what made remote_close remove the signal handler.)
    
    New test included.
    
    gdb/gdbserver/ChangeLog:
    2017-11-16  Pedro Alves  <palves@redhat.com>
    
    	* remote-utils.c (remote_close): Block SIGIO signals instead of
    	uninstalling the SIGIO handler.
    
    gdb/testsuite/ChangeLog:
    2017-11-16  Pedro Alves  <palves@redhat.com>
    
    	* gdb.server/reconnect-ctrl-c.c: New file.
    	* gdb.server/reconnect-ctrl-c.exp: New file.

Diff:
---
 gdb/gdbserver/ChangeLog                       |  5 ++
 gdb/gdbserver/remote-utils.c                  |  5 +-
 gdb/testsuite/ChangeLog                       |  5 ++
 gdb/testsuite/gdb.server/reconnect-ctrl-c.c   | 28 +++++++++++
 gdb/testsuite/gdb.server/reconnect-ctrl-c.exp | 72 +++++++++++++++++++++++++++
 5 files changed, 111 insertions(+), 4 deletions(-)

diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 7e72b7c..d091b43 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,8 @@
+2017-11-16  Pedro Alves  <palves@redhat.com>
+
+	* remote-utils.c (remote_close): Block SIGIO signals instead of
+	uninstalling the SIGIO handler.
+
 2017-11-16  Alan Hayward  <alan.hayward@arm.com>
 
 	* tdesc.c (tdesc_get_features_xml): Allow null osabi.
diff --git a/gdb/gdbserver/remote-utils.c b/gdb/gdbserver/remote-utils.c
index 54f27f4..2e4888a 100644
--- a/gdb/gdbserver/remote-utils.c
+++ b/gdb/gdbserver/remote-utils.c
@@ -378,10 +378,7 @@ remote_close (void)
 {
   delete_file_handler (remote_desc);
 
-#ifndef USE_WIN32API
-  /* Remove SIGIO handler.  */
-  signal (SIGIO, SIG_IGN);
-#endif
+  disable_async_io ();
 
 #ifdef USE_WIN32API
   closesocket (remote_desc);
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index d2b4983..a3dcd26 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-11-16  Pedro Alves  <palves@redhat.com>
+
+	* gdb.server/reconnect-ctrl-c.c: New file.
+	* gdb.server/reconnect-ctrl-c.exp: New file.
+
 2017-11-16  Phil Muldoon  <pmuldoon@redhat.com>
 
 	* gdb.python/py-rbreak.exp: New file.
diff --git a/gdb/testsuite/gdb.server/reconnect-ctrl-c.c b/gdb/testsuite/gdb.server/reconnect-ctrl-c.c
new file mode 100644
index 0000000..e722a6d
--- /dev/null
+++ b/gdb/testsuite/gdb.server/reconnect-ctrl-c.c
@@ -0,0 +1,28 @@
+/* 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>
+
+int
+main ()
+{
+  int secs = 30;
+
+  while (secs--)
+    sleep (1);
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.server/reconnect-ctrl-c.exp b/gdb/testsuite/gdb.server/reconnect-ctrl-c.exp
new file mode 100644
index 0000000..4571111
--- /dev/null
+++ b/gdb/testsuite/gdb.server/reconnect-ctrl-c.exp
@@ -0,0 +1,72 @@
+# 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/>.
+
+# Test that Ctrl-C works after reconnecting.
+
+load_lib gdbserver-support.exp
+
+if { [skip_gdbserver_tests] } {
+    verbose "skipping gdbserver tests"
+    return -1
+}
+
+standard_testfile
+if [prepare_for_testing "failed to prepare" $testfile $srcfile] {
+    return -1
+}
+
+# Make sure we're disconnected, in case we're testing with an
+# extended-remote board, therefore already connected.
+with_test_prefix "preparation" {
+  gdb_test "disconnect" ".*"
+}
+
+# Connect, continue, send Ctrl-C and expect a SIGINT stop.
+
+proc connect_continue_ctrl_c {} {
+    global gdbserver_protocol gdbserver_gdbport
+
+    set res [gdb_target_cmd $gdbserver_protocol $gdbserver_gdbport]
+    if ![gdb_assert {$res == 0} "connect"] {
+	return
+    }
+
+    set test "continue for ctrl-c"
+    gdb_test_multiple "continue" $test {
+	-re "Continuing" {
+	    pass $test
+	}
+    }
+
+    after 1000 {send_gdb "\003"}
+    gdb_test "" "Program received signal SIGINT.*" "stop with control-c"
+}
+
+with_test_prefix "first" {
+    # Start GDBserver.
+    set gdbserver_reconnect_p 1
+    set res [gdbserver_start "" $binfile]
+    set gdbserver_protocol [lindex $res 0]
+    set gdbserver_gdbport [lindex $res 1]
+
+    connect_continue_ctrl_c
+}
+
+with_test_prefix "second" {
+    gdb_test "disconnect" "Ending remote debugging."
+    connect_continue_ctrl_c
+}