GDB support for Android in devtools' debugger.

mojo/devtools/common/android_gdb/session.py

Index: mojo/devtools/common/android_gdb/session.py
diff --git a/mojo/devtools/common/android_gdb/session.py b/mojo/devtools/common/android_gdb/session.py
new file mode 100644
index 0000000000000000000000000000000000000000..80786d57a7504d70b68fae9ea89b16536fdd96fe
--- /dev/null
+++ b/mojo/devtools/common/android_gdb/session.py
@@ -0,0 +1,241 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import gdb
+import glob
+import itertools
+import os
+import os.path
+import re

[ppi, 2015/06/24 15:14:07]

Unused.

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

Done.

+import shutil
+import socket

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

Unused?

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

Done.

+import struct

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

Unused.

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

Done.

+import subprocess
+import sys
+import tempfile
+import time
+
+
+sys.path.append(os.path.dirname(os.path.abspath(__file__)))
+import config
+from remote_file_connection import RemoteFileConnection
+
+
+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 gdb_execute(command):
+  """Execute a GDB command."""

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

s/Execute/Executes/

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

Done.

+  return gdb.execute(command, to_string=True)
+
+
+class Mapping(object):
+  def __init__(self, line):
+    self.start = int(line[0], 16)
+    self.end = int(line[1], 16)
+    self.size = int(line[2], 16)
+    self.offset = int(line[3], 16)
+    self.filename = line[4]
+
+
+def get_mapped_files():
+  mappings = [Mapping(x) for x in
+              [x.split() for x in
+               gdb_execute("info proc map").split('\n')]
+              if len(x) == 5 and x[4][0] == '/']
+  res = {}
+  for m in mappings:
+    libname = m.filename[m.filename.rfind('/') + 1:]
+    res[libname] = res.get(libname, []) + [m]
+  return res.values()
+
+
+class DebugSession(object):
+  def __init__(self,
+               build_directory=os.path.join(
+                   _GetDirAbove('out'), 'out', 'android_Debug'),
+               package_name='org.chromium.mojo.shell',
+               adb='adb',
+               third_party_dir=os.path.join(
+                   _GetDirAbove('third_party'), 'third_party')):
+    self.build_directory = build_directory
+    self.package_name = package_name
+    self.adb = adb
+    self.remote_file_cache = os.path.join(os.getenv('HOME'), '.mojosymbols')
+
+    sys.path.append(os.path.join(third_party_dir, 'pyelftools'))

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

devtools are meant to be consumed in other repositories, too. It's fine to try
to use the one in third party, but add a check if this succeeded, and if not,
print an informative error message. (Couldn't import pyelftools, run `pip
install ...` if you want to install it.)

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

Done.

+    import elftools.elf.elffile as elffile
+    self._elffile = elffile
+
+    self.libraries = self._find_libraries(build_directory)
+    self.rfc = RemoteFileConnection('localhost', 10000)
+    if not os.path.exists(self.remote_file_cache):
+      os.makedirs(self.remote_file_cache)
+    self.done_mapping = set()
+    self._downloaded_files = []
+
+  def __del__(self):
+    gdbserver_pid = self._get_pid('gdbserver')
+    if gdbserver_pid is not None:
+      subprocess.check_call([self.adb, 'shell', 'kill', gdbserver_pid])
+    remote_file_reader_pid = self._get_pid('remote_file_reader')
+    if remote_file_reader_pid is not None:
+      subprocess.check_call([self.adb, 'shell', 'kill', remote_file_reader_pid])
+
+  def _find_libraries(self, lib_dir):
+    res = {}
+    for fn in glob.glob('%s/*.so' % lib_dir):
+      with open(fn, 'r') as f:
+        s = self._get_signature(f)
+        if s is not None:
+          res[s] = fn
+    return res
+
+

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

Single blank lines between class members, please.

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

Done.

+  def _get_signature(self, file_object):
+    """Compute a unique signature of a library file."""
+    elf = self._elffile.ELFFile(file_object)
+    text_section = elf.get_section_by_name('.text')
+    file_object.seek(text_section['sh_offset'])
+    data = file_object.read(min(4096, text_section['sh_size']))
+    def combine((i, c)):
+      return i ^ ord(c)
+    result = 16 * [ 0 ]

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

Remove spaces around "0".

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

Done.

+    for i in xrange(0, len(data), len(result)):
+      result = map(combine,
+                   itertools.izip_longest(result,
+                                          data[i:i+len(result)],

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

Add spaces around "+".

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

Done.

+                                          fillvalue='\0'))
+    return ''.join(["%02x" % x for x in result])
+
+  def _associate_symbols(self, mapping, local_file):
+    with open(local_file, "r") as f:
+      elf = self._elffile.ELFFile(f)
+      s = elf.get_section_by_name(".text")
+      text_address = mapping[0].start + s['sh_offset']
+      gdb_execute("add-symbol-file %s 0x%x" % (local_file, text_address))
+
+  def _download_file(self, remote):
+    """Download a remote file through GDB connection.

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

s/Download/Downloads/

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

Done.

+
+    Returns the filename

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

The format is:
"""
Returns:
  What is being returned
"""

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

Done.

+    """
+    temp_file = tempfile.NamedTemporaryFile()
+    gdb_execute("remote get %s %s" % (remote, temp_file.name))
+    # This allows the deletion of temporary files on disk when the debugging
+    # session terminates.
+    self._downloaded_files.append(temp_file)
+    return temp_file.name
+
+  def _download_and_associate_symbol(self, mapping):
+    self._associate_symbols(mapping, self._download_file(mapping[0].filename))
+
+  def _find_mapping_for_address(self, mappings, address):
+    for m in mappings:
+      for s in m:
+        if address >= s.start and address <= s.end:
+          return m
+    return None
+
+  def _try_to_map(self, mapping):
+    remote_file = mapping[0].filename
+    if remote_file in self.done_mapping:
+      return False
+    self.done_mapping.add(remote_file)
+    self.rfc.open(remote_file)
+    s = self._get_signature(self.rfc)
+    if s is not None:
+      if s in self.libraries:
+        self._associate_symbols(mapping, self.libraries[s])
+      else:
+        local_file = os.path.join(self.remote_file_cache, s)
+        if not os.path.exists(local_file):
+          tmp_output = self._download_file(remote_file)
+          shutil.move(tmp_output, local_file)
+        self._associate_symbols(mapping, local_file)
+      return True
+    return False
+
+  def _update_symbols(self):
+    """Update the mapping between symbols as seen from GDB and local library

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

s/Update/Updates/

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

Done.

+    files."""
+    mapped_files = get_mapped_files()
+    gdb_execute("info threads")
+    nb_threads = len(gdb_execute("info threads").split("\n")) - 2
+    # Map all symbols in /data/
+    for m in mapped_files:
+      filename = m[0].filename
+      if ((filename.startswith('/data/data/') or
+           filename.startswith('/data/app')) and
+          not filename.endswith('.apk') and
+          not filename.endswith('.dex')):
+        print 'Pre-mapping: %s' % m[0].filename
+        self._try_to_map(m)
+    for i in xrange(nb_threads):
+      try:
+        gdb_execute("thread %d" % (i + 1))
+        frame = gdb.newest_frame()
+        while frame and frame.is_valid():
+          if frame.name() is None:
+            m = self._find_mapping_for_address(mapped_files, frame.pc())
+            if m is not None and self._try_to_map(m):
+              # Force gdb to recompute its frames.
+              gdb_execute("info threads")
+              frame = gdb.newest_frame()
+              assert frame.is_valid()
+          if (frame.older() is not None and
+              frame.older().is_valid() and
+              frame.older().pc() != frame.pc()):
+            frame = frame.older()
+          else:
+            frame = None
+      except gdb.error as _:
+        import traceback
+        traceback.print_exc()
+
+

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

Just one blank line.

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

Done.

+  def _get_pid(self, application):
+    """Get the PID of an application running on a device."""

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

s/Get/Gets/

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

Done.

+    output = subprocess.check_output([self.adb, 'shell', 'ps'])
+    for line in output.split('\n'):
+      elements = line.split()
+      if len(elements) > 0 and elements[-1] == application:
+        return elements[1]
+    return None
+
+  def start_debug(self):
+    """Start a debugging session."""

[ppi, 2015/06/24 15:14:07]

s/Start/Starts/

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

Done.

+    gdbserver_pid = self._get_pid('gdbserver')
+    if gdbserver_pid is not None:
+      subprocess.check_call([self.adb, 'shell', 'kill', gdbserver_pid])
+    shell_pid = self._get_pid(self.package_name)
+    if shell_pid is None:
+      raise Exception('Unable to find a running mojo shell.')
+    subprocess.check_call([self.adb, 'forward', 'tcp:9999', 'tcp:9999'])
+    subprocess.Popen(
+        [self.adb, 'shell', 'gdbserver', '--attach', ':9999', shell_pid])
+    time.sleep(0.1)
+
+    read_process = subprocess.Popen(
+        [self.adb, 'shell', config.REMOTE_FILE_READER_DEVICE_PATH],
+        stdout=subprocess.PIPE)
+    port = int(read_process.stdout.readline())
+    subprocess.check_call([self.adb, 'forward', 'tcp:10000', 'tcp:%d' % port])
+    self.rfc.connect()
+
+    gdb_execute('target remote localhost:9999')
+
+    self._update_symbols()
+    def on_stop(_):
+      self._update_symbols()
+    gdb.events.stop.connect(on_stop)
+

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

Remove the trailing blank lines.

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

Done.

+