GDB support for Android in devtools' debugger.

mojo/devtools/common/debugger

Index: mojo/devtools/common/debugger
diff --git a/mojo/devtools/common/debugger b/mojo/devtools/common/debugger
index b323f4ac6b2f1221cd9658f81716b46dc235dca1..9bd313ecc4e85b6c9086b9ec4219408881647678 100755
--- a/mojo/devtools/common/debugger
+++ b/mojo/devtools/common/debugger
@@ -8,10 +8,22 @@ import os.path
 import requests
 import subprocess
 import sys
+import tempfile

[ppi, 2015/06/24 15:14:08]

add a blank line

[etiennej, 2015/06/29 15:41:43]

Done.

+from android_gdb.install_remote_file_reader import install_binary
 
 _MOJO_DEBUGGER_PORT = 7777
 
 
+def _GetDirAbove(dirname):
+  """Returns the directory "above" this file containing |dirname|."""
+  path = os.path.abspath(__file__)
+  while True:
+    path, _ = os.path.split(path)
+    assert path
+    if dirname in os.listdir(path):
+      return path
+
+
 def _send_request(request, payload=None):
   """Sends a request to mojo:debugger."""
   try:
@@ -132,24 +144,86 @@ def _device_stack(args):
   return 0
 
 
+def _device_gdb(args):
+  """Run GDB on an instance of Mojo Shell on an android device."""
+  if args.ndk_dir:
+    ndk_dir = args.ndk_dir
+  else:
+    ndk_dir = os.path.join(_GetDirAbove('third_party'), 'third_party',

[ppi, 2015/06/24 15:14:08]

We already have similar logic in devtools, in `stack`. We should probably move
these two here:

def _LowestAncestorContainingRelpath(dir_path, relpath):
def _GuessDir(relpath):

, and pass already inferred paths to `stack`.

We can do it in a separate CL if you prefer.

[etiennej, 2015/06/29 15:41:42]

Added a TODO.

+                           'android_tools', 'ndk')
+  install_args = {}
+  if args.gsutil_dir:
+    install_args['gsutil'] = os.path.join(args.gsutil_dir, 'gsutil')
+  else:
+    install_args['gsutil'] = os.path.join(
+        _GetDirAbove('depot_tools'), 'depot_tools', 'third_party', 'gsutil',
+        'gsutil')
+  if args.adb_path:
+    install_args['adb'] = args.adb_path
+  install_binary(**install_args)
+
+  gdb_path = os.path.join(
+      ndk_dir,
+      'toolchains',
+      # TODO(etiennej): Always select the most recent toolchain?
+      'arm-linux-androideabi-4.9',
+      'prebuilt',
+      # TODO(etiennej): DEPS mac NDK and use it on macs.
+      'linux-x86_64',
+      'bin',
+      'arm-linux-androideabi-gdb')
+  python_gdb_script_path = os.path.join(os.path.dirname(__file__),
+                                        'android_gdb', 'session.py')
+  # We need to pass some commands to GDB at startup

[ppi, 2015/06/24 15:14:08]

End with a period.

[etiennej, 2015/06/29 15:41:43]

Done.

+  gdb_setup_commands = tempfile.NamedTemporaryFile()
+  gdb_setup_commands.write('source ' + python_gdb_script_path + '\n')
+  debug_session_arguments = {}
+  if args.build_dir:
+    debug_session_arguments["build_directory"] = args.build_dir
+  if args.package_name:
+    debug_session_arguments["package_name"] = args.package_name
+  if args.third_party_dir:
+    debug_session_arguments["third_party_dir"] = args.third_party_dir
+  debug_session_arguments = ', '.join([k + '=' + string_escape(v) for

[ppi, 2015/06/24 15:14:08]

Where string_escape is defined or imported?

[etiennej, 2015/06/29 15:41:43]

Done.

+                                       k, v in debug_session_arguments.items()])
+  gdb_setup_commands.write('py d = DebugSession('+debug_session_arguments+')\n')

[ppi, 2015/06/24 15:14:08]

Add spaced around "+"es.

[etiennej, 2015/06/29 15:41:43]

Done.

+  gdb_setup_commands.write('py d.start_debug()\n')
+  gdb_setup_commands.flush()
+  gdb_proc = subprocess.Popen([gdb_path, '-x', gdb_setup_commands.name],
+                              stdin=sys.stdin,
+                              stdout=sys.stdout,
+                              stderr=sys.stderr)
+  gdb_proc.wait()
+
+
 def _add_device_command(subparsers):
   """Sets up the parser for the 'device' command."""
   device_parser = subparsers.add_parser('device',
       help='interact with the Android device (requires adb in PATH or passing '
            '--adb-path)')
   device_parser.add_argument('--adb-path', type=str,
-      help='path to the adb tool from the Android SDK')
+      help='path to the adb tool from the Android SDK (optional)')
+  device_parser.add_argument('--ndk-dir', type=str,
+      help='path to the directory containing the Android NDK')
+  device_parser.add_argument('--build-dir', type=str,
+      help='path to the build directory')
   device_subparser = device_parser.add_subparsers(
       help='the command to run')
 
   device_stack_parser = device_subparser.add_parser('stack',
       help='symbolize the crash stacktraces from the device log')
-  device_stack_parser.add_argument('--build-dir', type=str,
-      help='path to the build directory')
-  device_stack_parser.add_argument('--ndk-dir', type=str,
-      help='path to the directory containing the Android NDK')
   device_stack_parser.set_defaults(func=_device_stack)
 
+  device_gdb_parser = device_subparser.add_parser('gdb',
+      help='debug a shell instance currently running on a device')

[ppi, 2015/06/24 15:14:08]

"debug" doesn't say much. Please clarify that we are attaching to a shell
already running under gdb, or whatever else exactly it is that we are doing.

[etiennej, 2015/06/29 15:41:43]

Done.

+  device_gdb_parser.add_argument('--third_party_dir', type=str,
+      help='Path to a directory containing third party libraries')
+  device_gdb_parser.add_argument('--gsutil_dir', type=str,
+      help='Path to a directory containing gsutil')
+  device_gdb_parser.add_argument('--package_name', type=str,
+      help='Name of the Mojo Shell android package to debug')
+  device_gdb_parser.set_defaults(func=_device_gdb)

[qsr, 2015/06/24 15:29:01]

Hum. It would be good if that worked also for desktop. I think we should have an
API to use gdb, and the specifics should go in a library with one implementation
for desktop and one implementation of android. The same way we do for launching
the shell.

[etiennej, 2015/06/29 15:41:43]

My understanding is that ppi@ wanted to have all android-related tools under the
same switch ("device"), and I am sharing a number of flags with "device stack".
However, I would be happy to move the flags and switches elsewhere. ppi@: what
do you think?

+
 
 def main():
   parser = argparse.ArgumentParser(description='Command-line interface for '