[gnome-builder/wip/chergert/debugger: 32/58] gdb: hook up some client signals and plumbing

[Christian Hergert <chergert src gnome org>]

commit d96a1d6b05e693163deeb7dc427d90113f9cc996
Author: Christian Hergert <chergert redhat com>
Date:   Fri Mar 24 02:59:39 2017 -0700

    gdb: hook up some client signals and plumbing

 plugins/gdb/gdb_plugin.py |   96 +++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 93 insertions(+), 3 deletions(-)
---
diff --git a/plugins/gdb/gdb_plugin.py b/plugins/gdb/gdb_plugin.py
index fc79cbb..484fc8a 100644
--- a/plugins/gdb/gdb_plugin.py
+++ b/plugins/gdb/gdb_plugin.py
@@ -19,15 +19,34 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 
+import os
+
 from gi.repository import GLib
 from gi.repository import GObject
+from gi.repository import Gio
 from gi.repository import Ide
+from gi.repository import Mi2
 
 class GdbDebugger(Ide.Object, Ide.Debugger):
     can_step_in = GObject.Property('can-step-in', type=bool, default=False)
     can_step_over = GObject.Property('can-step-over', type=bool, default=False)
     can_continue = GObject.Property('can-continue', type=bool, default=False)
 
+    # If we've stolen a PTY from the runner to be used later,
+    # it will be here. This should be close()d if we do not
+    # get a chance to assitn it using gdb.
+    inferior_pty = None
+
+    # Our Mi2.Client is what we use to communicate with the controlling gdb
+    # process over stdin/stdout.
+    client = None
+
+    def __del__(self):
+        if self.inferior_pty is not None:
+            os.close(self.inferior_pty)
+        if self.client:
+            self.client.stop_listening()
+
     def do_get_name(self):
         return 'GNU Debugger'
 
@@ -38,8 +57,79 @@ class GdbDebugger(Ide.Object, Ide.Debugger):
             return (False, 0)
 
     def do_prepare(self, runner):
-        gdb_arguments = ['gdb', '-ex', 'run', '--args']
-
-        for arg in reversed(gdb_arguments):
+        # Run the program under gdb so that we can control the debugger
+        # with stdin/stdout.
+        for arg in reversed(['gdb', '--interpreter', 'mi2', '--args']):
             runner.prepend_argv(arg)
 
+        # Connect to signals so we can setup/cleanup properly
+        runner.connect('spawned', self.on_runner_spawned)
+        runner.connect('exited', self.on_runner_exited)
+
+        # We need to steal the TTY from the runner (if there is one) so
+        # that we can tell GDB to use it. But we need our own access to
+        # gdb over a regular stdin/stdout pipe.
+        self.inferior_pty = runner.steal_tty()
+
+        # We need access to stdin/stdout so that we can communicate with
+        # the gdb process.
+        runner.set_flags(Gio.SubprocessFlags.STDIN_PIPE | Gio.SubprocessFlags.STDOUT_PIPE)
+
+    def on_runner_spawned(self, runner, identifier):
+        # Create our client to communicate with gdb
+        io_stream = Gio.SimpleIOStream.new(runner.get_stdout(), runner.get_stdin())
+        self.client = Mi2.Client.new(io_stream)
+
+        # Connect to all the signals we need from the client before we ask it to start
+        # processing incoming messages. We don't want to lose anything.
+        self.client.connect('breakpoint-inserted', self.on_client_breakpoint_inserted)
+        self.client.connect('breakpoint-removed', self.on_client_breakpoint_removed)
+        self.client.connect('event', self.on_client_event)
+        self.client.connect('stopped', self.on_client_stopped)
+        self.client.connect('log', self.on_client_log)
+
+        # Start the async read loop for the client to process replies.
+        self.client.start_listening()
+
+        # We stole the pty from the runner so that we could pass it to gdb
+        # instead. This will ensure that gdb re-opens that pty. Since gdb is
+        # in the same sandbox as the application, this should Just Work™.
+        command = '-gdb-set inferior-tty {}'.format(os.ttyname(self.inferior_pty))
+        self.client.exec_async(command, None, self.on_client_exec_cb)
+
+        # Add a breakpoint at main()
+        #breakpoint = Mi2.Breakpoint(function='main')
+        #self.client.insert_breakpoint_async(breakpoint, None)
+
+        # Now ask gdb to start the inferior
+        self.client.run_async(None, self.on_client_run_cb)
+
+    def on_client_run_cb(self, client, result):
+        try:
+            ret = client.run_finish(result)
+        except Exception as ex:
+            print(repr(ex))
+
+    def on_client_exec_cb(self, client, result):
+        try:
+            ret = client.exec_finish(result)
+        except Exception as ex:
+            print(repr(ex))
+
+    def on_runner_exited(self, runner):
+        self.client.stop_listening()
+
+    def on_client_log(self, client, message):
+        print('>>>', message[:-1])
+
+    def on_client_event(self, client, message):
+        print('Event: {}'.format(message.get_name()))
+
+    def on_client_breakpoint_inserted(self, client, breakpoint):
+        print('Breakpoint inserted {}'.format(breakpoint))
+
+    def on_client_breakpoint_removed(self, client, breakpoint_id):
+        print('Breakpoint removed{}'.format(breakpoint_id))
+
+    def on_client_stopped(self, client, reason, message):
+        print('::stopped {}'.format(reason))