diff --git a/adb/__init__.py b/adb/__init__.py
deleted file mode 100644
index 6b509c6..0000000
--- a/adb/__init__.py
+++ /dev/null
@@ -1,17 +0,0 @@
-#
-# Copyright (C) 2015 The Android Open Source Project
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-from __future__ import absolute_import
-from .device import *  # pylint: disable=wildcard-import
diff --git a/adb/adb_trace.h b/adb/adb_trace.h
index 623108e..b4155df 100644
--- a/adb/adb_trace.h
+++ b/adb/adb_trace.h
@@ -50,9 +50,7 @@
 #define D(...) \
         do { \
             if (ADB_TRACING) { \
-                int saved_errno = errno; \
                 LOG(INFO) << android::base::StringPrintf(__VA_ARGS__); \
-                errno = saved_errno; \
            } \
         } while (0)
 
diff --git a/adb/device.py b/adb/device.py
deleted file mode 100644
index 516e880..0000000
--- a/adb/device.py
+++ /dev/null
@@ -1,339 +0,0 @@
-#
-# Copyright (C) 2015 The Android Open Source Project
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-import logging
-import os
-import re
-import subprocess
-import tempfile
-
-
-class FindDeviceError(RuntimeError):
-    pass
-
-
-class DeviceNotFoundError(FindDeviceError):
-    def __init__(self, serial):
-        self.serial = serial
-        super(DeviceNotFoundError, self).__init__(
-            'No device with serial {}'.format(serial))
-
-
-class NoUniqueDeviceError(FindDeviceError):
-    def __init__(self):
-        super(NoUniqueDeviceError, self).__init__('No unique device')
-
-
-class ShellError(RuntimeError):
-    def __init__(self, cmd, stdout, stderr, exit_code):
-        super(ShellError, self).__init__(
-                '`{0}` exited with code {1}'.format(cmd, exit_code))
-        self.cmd = cmd
-        self.stdout = stdout
-        self.stderr = stderr
-        self.exit_code = exit_code
-
-
-def get_devices():
-    with open(os.devnull, 'wb') as devnull:
-        subprocess.check_call(['adb', 'start-server'], stdout=devnull,
-                              stderr=devnull)
-    out = subprocess.check_output(['adb', 'devices']).splitlines()
-
-    # The first line of `adb devices` just says "List of attached devices", so
-    # skip that.
-    devices = []
-    for line in out[1:]:
-        if not line.strip():
-            continue
-        if 'offline' in line:
-            continue
-
-        serial, _ = re.split(r'\s+', line, maxsplit=1)
-        devices.append(serial)
-    return devices
-
-
-def _get_unique_device(product=None):
-    devices = get_devices()
-    if len(devices) != 1:
-        raise NoUniqueDeviceError()
-    return AndroidDevice(devices[0], product)
-
-
-def _get_device_by_serial(serial, product=None):
-    for device in get_devices():
-        if device == serial:
-            return AndroidDevice(serial, product)
-    raise DeviceNotFoundError(serial)
-
-
-def get_device(serial=None, product=None):
-    """Get a uniquely identified AndroidDevice if one is available.
-
-    Raises:
-        DeviceNotFoundError:
-            The serial specified by `serial` or $ANDROID_SERIAL is not
-            connected.
-
-        NoUniqueDeviceError:
-            Neither `serial` nor $ANDROID_SERIAL was set, and the number of
-            devices connected to the system is not 1. Having 0 connected
-            devices will also result in this error.
-
-    Returns:
-        An AndroidDevice associated with the first non-None identifier in the
-        following order of preference:
-
-        1) The `serial` argument.
-        2) The environment variable $ANDROID_SERIAL.
-        3) The single device connnected to the system.
-    """
-    if serial is not None:
-        return _get_device_by_serial(serial, product)
-
-    android_serial = os.getenv('ANDROID_SERIAL')
-    if android_serial is not None:
-        return _get_device_by_serial(android_serial, product)
-
-    return _get_unique_device(product)
-
-# Call this instead of subprocess.check_output() to work-around issue in Python
-# 2's subprocess class on Windows where it doesn't support Unicode. This
-# writes the command line to a UTF-8 batch file that is properly interpreted
-# by cmd.exe.
-def _subprocess_check_output(*popenargs, **kwargs):
-    # Only do this slow work-around if Unicode is in the cmd line.
-    if (os.name == 'nt' and
-            any(isinstance(arg, unicode) for arg in popenargs[0])):
-        # cmd.exe requires a suffix to know that it is running a batch file
-        tf = tempfile.NamedTemporaryFile('wb', suffix='.cmd', delete=False)
-        # @ in batch suppresses echo of the current line.
-        # Change the codepage to 65001, the UTF-8 codepage.
-        tf.write('@chcp 65001 > nul\r\n')
-        tf.write('@')
-        # Properly quote all the arguments and encode in UTF-8.
-        tf.write(subprocess.list2cmdline(popenargs[0]).encode('utf-8'))
-        tf.close()
-
-        try:
-            result = subprocess.check_output(['cmd.exe', '/c', tf.name],
-                                             **kwargs)
-        except subprocess.CalledProcessError as e:
-            # Show real command line instead of the cmd.exe command line.
-            raise subprocess.CalledProcessError(e.returncode, popenargs[0],
-                                                output=e.output)
-        finally:
-            os.remove(tf.name)
-        return result
-    else:
-        return subprocess.check_output(*popenargs, **kwargs)
-
-class AndroidDevice(object):
-    # Delimiter string to indicate the start of the exit code.
-    _RETURN_CODE_DELIMITER = 'x'
-
-    # Follow any shell command with this string to get the exit
-    # status of a program since this isn't propagated by adb.
-    #
-    # The delimiter is needed because `printf 1; echo $?` would print
-    # "10", and we wouldn't be able to distinguish the exit code.
-    _RETURN_CODE_PROBE_STRING = 'echo "{0}$?"'.format(_RETURN_CODE_DELIMITER)
-
-    # Maximum search distance from the output end to find the delimiter.
-    # adb on Windows returns \r\n even if adbd returns \n.
-    _RETURN_CODE_SEARCH_LENGTH = len('{0}255\r\n'.format(_RETURN_CODE_DELIMITER))
-
-    # Shell protocol feature string.
-    SHELL_PROTOCOL_FEATURE = 'shell_2'
-
-    def __init__(self, serial, product=None):
-        self.serial = serial
-        self.product = product
-        self.adb_cmd = ['adb']
-        if self.serial is not None:
-            self.adb_cmd.extend(['-s', serial])
-        if self.product is not None:
-            self.adb_cmd.extend(['-p', product])
-        self._linesep = None
-        self._features = None
-
-    @property
-    def linesep(self):
-        if self._linesep is None:
-            self._linesep = subprocess.check_output(self.adb_cmd +
-                                                    ['shell', 'echo'])
-        return self._linesep
-
-    @property
-    def features(self):
-        if self._features is None:
-            try:
-                self._features = self._simple_call(['features']).splitlines()
-            except subprocess.CalledProcessError:
-                self._features = []
-        return self._features
-
-    def _make_shell_cmd(self, user_cmd):
-        command = self.adb_cmd + ['shell'] + user_cmd
-        if self.SHELL_PROTOCOL_FEATURE not in self.features:
-            command.append('; ' + self._RETURN_CODE_PROBE_STRING)
-        return command
-
-    def _parse_shell_output(self, out):
-        """Finds the exit code string from shell output.
-
-        Args:
-            out: Shell output string.
-
-        Returns:
-            An (exit_code, output_string) tuple. The output string is
-            cleaned of any additional stuff we appended to find the
-            exit code.
-
-        Raises:
-            RuntimeError: Could not find the exit code in |out|.
-        """
-        search_text = out
-        if len(search_text) > self._RETURN_CODE_SEARCH_LENGTH:
-            # We don't want to search over massive amounts of data when we know
-            # the part we want is right at the end.
-            search_text = search_text[-self._RETURN_CODE_SEARCH_LENGTH:]
-        partition = search_text.rpartition(self._RETURN_CODE_DELIMITER)
-        if partition[1] == '':
-            raise RuntimeError('Could not find exit status in shell output.')
-        result = int(partition[2])
-        # partition[0] won't contain the full text if search_text was truncated,
-        # pull from the original string instead.
-        out = out[:-len(partition[1]) - len(partition[2])]
-        return result, out
-
-    def _simple_call(self, cmd):
-        logging.info(' '.join(self.adb_cmd + cmd))
-        return _subprocess_check_output(
-            self.adb_cmd + cmd, stderr=subprocess.STDOUT)
-
-    def shell(self, cmd):
-        """Calls `adb shell`
-
-        Args:
-            cmd: string shell command to execute.
-
-        Returns:
-            A (stdout, stderr) tuple. Stderr may be combined into stdout
-            if the device doesn't support separate streams.
-
-        Raises:
-            ShellError: the exit code was non-zero.
-        """
-        exit_code, stdout, stderr = self.shell_nocheck(cmd)
-        if exit_code != 0:
-            raise ShellError(cmd, stdout, stderr, exit_code)
-        return stdout, stderr
-
-    def shell_nocheck(self, cmd):
-        """Calls `adb shell`
-
-        Args:
-            cmd: string shell command to execute.
-
-        Returns:
-            An (exit_code, stdout, stderr) tuple. Stderr may be combined
-            into stdout if the device doesn't support separate streams.
-        """
-        cmd = self._make_shell_cmd(cmd)
-        logging.info(' '.join(cmd))
-        p = subprocess.Popen(
-            cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-        stdout, stderr = p.communicate()
-        if self.SHELL_PROTOCOL_FEATURE in self.features:
-            exit_code = p.returncode
-        else:
-            exit_code, stdout = self._parse_shell_output(stdout)
-        return exit_code, stdout, stderr
-
-    def install(self, filename, replace=False):
-        cmd = ['install']
-        if replace:
-            cmd.append('-r')
-        cmd.append(filename)
-        return self._simple_call(cmd)
-
-    def push(self, local, remote):
-        return self._simple_call(['push', local, remote])
-
-    def pull(self, remote, local):
-        return self._simple_call(['pull', remote, local])
-
-    def sync(self, directory=None):
-        cmd = ['sync']
-        if directory is not None:
-            cmd.append(directory)
-        return self._simple_call(cmd)
-
-    def forward(self, local, remote):
-        return self._simple_call(['forward', local, remote])
-
-    def tcpip(self, port):
-        return self._simple_call(['tcpip', port])
-
-    def usb(self):
-        return self._simple_call(['usb'])
-
-    def reboot(self):
-        return self._simple_call(['reboot'])
-
-    def root(self):
-        return self._simple_call(['root'])
-
-    def unroot(self):
-        return self._simple_call(['unroot'])
-
-    def forward_remove(self, local):
-        return self._simple_call(['forward', '--remove', local])
-
-    def forward_remove_all(self):
-        return self._simple_call(['forward', '--remove-all'])
-
-    def connect(self, host):
-        return self._simple_call(['connect', host])
-
-    def disconnect(self, host):
-        return self._simple_call(['disconnect', host])
-
-    def reverse(self, remote, local):
-        return self._simple_call(['reverse', remote, local])
-
-    def reverse_remove_all(self):
-        return self._simple_call(['reverse', '--remove-all'])
-
-    def reverse_remove(self, remote):
-        return self._simple_call(['reverse', '--remove', remote])
-
-    def wait(self):
-        return self._simple_call(['wait-for-device'])
-
-    def get_prop(self, prop_name):
-        output = self.shell(['getprop', prop_name])[0].splitlines()
-        if len(output) != 1:
-            raise RuntimeError('Too many lines in getprop output:\n' +
-                               '\n'.join(output))
-        value = output[0]
-        if not value.strip():
-            return None
-        return value
-
-    def set_prop(self, prop_name, value):
-        self.shell(['setprop', prop_name, value])
diff --git a/adb/test_device.py b/adb/test_device.py
deleted file mode 100644
index d033a01..0000000
--- a/adb/test_device.py
+++ /dev/null
@@ -1,537 +0,0 @@
-#!/usr/bin/env python
-# -*- coding: utf-8 -*-
-#
-# Copyright (C) 2015 The Android Open Source Project
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-from __future__ import print_function
-
-import hashlib
-import os
-import posixpath
-import random
-import shlex
-import shutil
-import signal
-import subprocess
-import tempfile
-import unittest
-
-import mock
-
-import adb
-
-
-def requires_root(func):
-    def wrapper(self, *args):
-        if self.device.get_prop('ro.debuggable') != '1':
-            raise unittest.SkipTest('requires rootable build')
-
-        was_root = self.device.shell(['id', '-un'])[0].strip() == 'root'
-        if not was_root:
-            self.device.root()
-            self.device.wait()
-
-        try:
-            func(self, *args)
-        finally:
-            if not was_root:
-                self.device.unroot()
-                self.device.wait()
-
-    return wrapper
-
-
-class GetDeviceTest(unittest.TestCase):
-    def setUp(self):
-        self.android_serial = os.getenv('ANDROID_SERIAL')
-        if 'ANDROID_SERIAL' in os.environ:
-            del os.environ['ANDROID_SERIAL']
-
-    def tearDown(self):
-        if self.android_serial is not None:
-            os.environ['ANDROID_SERIAL'] = self.android_serial
-        else:
-            if 'ANDROID_SERIAL' in os.environ:
-                del os.environ['ANDROID_SERIAL']
-
-    @mock.patch('adb.device.get_devices')
-    def test_explicit(self, mock_get_devices):
-        mock_get_devices.return_value = ['foo', 'bar']
-        device = adb.get_device('foo')
-        self.assertEqual(device.serial, 'foo')
-
-    @mock.patch('adb.device.get_devices')
-    def test_from_env(self, mock_get_devices):
-        mock_get_devices.return_value = ['foo', 'bar']
-        os.environ['ANDROID_SERIAL'] = 'foo'
-        device = adb.get_device()
-        self.assertEqual(device.serial, 'foo')
-
-    @mock.patch('adb.device.get_devices')
-    def test_arg_beats_env(self, mock_get_devices):
-        mock_get_devices.return_value = ['foo', 'bar']
-        os.environ['ANDROID_SERIAL'] = 'bar'
-        device = adb.get_device('foo')
-        self.assertEqual(device.serial, 'foo')
-
-    @mock.patch('adb.device.get_devices')
-    def test_no_such_device(self, mock_get_devices):
-        mock_get_devices.return_value = ['foo', 'bar']
-        self.assertRaises(adb.DeviceNotFoundError, adb.get_device, ['baz'])
-
-        os.environ['ANDROID_SERIAL'] = 'baz'
-        self.assertRaises(adb.DeviceNotFoundError, adb.get_device)
-
-    @mock.patch('adb.device.get_devices')
-    def test_unique_device(self, mock_get_devices):
-        mock_get_devices.return_value = ['foo']
-        device = adb.get_device()
-        self.assertEqual(device.serial, 'foo')
-
-    @mock.patch('adb.device.get_devices')
-    def test_no_unique_device(self, mock_get_devices):
-        mock_get_devices.return_value = ['foo', 'bar']
-        self.assertRaises(adb.NoUniqueDeviceError, adb.get_device)
-
-
-class DeviceTest(unittest.TestCase):
-    def setUp(self):
-        self.device = adb.get_device()
-
-
-class ShellTest(DeviceTest):
-    def test_cat(self):
-        """Check that we can at least cat a file."""
-        out = self.device.shell(['cat', '/proc/uptime'])[0].strip()
-        elements = out.split()
-        self.assertEqual(len(elements), 2)
-
-        uptime, idle = elements
-        self.assertGreater(float(uptime), 0.0)
-        self.assertGreater(float(idle), 0.0)
-
-    def test_throws_on_failure(self):
-        self.assertRaises(adb.ShellError, self.device.shell, ['false'])
-
-    def test_output_not_stripped(self):
-        out = self.device.shell(['echo', 'foo'])[0]
-        self.assertEqual(out, 'foo' + self.device.linesep)
-
-    def test_shell_nocheck_failure(self):
-        rc, out, _ = self.device.shell_nocheck(['false'])
-        self.assertNotEqual(rc, 0)
-        self.assertEqual(out, '')
-
-    def test_shell_nocheck_output_not_stripped(self):
-        rc, out, _ = self.device.shell_nocheck(['echo', 'foo'])
-        self.assertEqual(rc, 0)
-        self.assertEqual(out, 'foo' + self.device.linesep)
-
-    def test_can_distinguish_tricky_results(self):
-        # If result checking on ADB shell is naively implemented as
-        # `adb shell <cmd>; echo $?`, we would be unable to distinguish the
-        # output from the result for a cmd of `echo -n 1`.
-        rc, out, _ = self.device.shell_nocheck(['echo', '-n', '1'])
-        self.assertEqual(rc, 0)
-        self.assertEqual(out, '1')
-
-    def test_line_endings(self):
-        """Ensure that line ending translation is not happening in the pty.
-
-        Bug: http://b/19735063
-        """
-        output = self.device.shell(['uname'])[0]
-        self.assertEqual(output, 'Linux' + self.device.linesep)
-
-    def test_pty_logic(self):
-        """Verify PTY logic for shells.
-
-        Interactive shells should use a PTY, non-interactive should not.
-
-        Bug: http://b/21215503
-        """
-        proc = subprocess.Popen(
-                self.device.adb_cmd + ['shell'], stdin=subprocess.PIPE,
-                stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
-        # [ -t 0 ] is used (rather than `tty`) to provide portability. This
-        # gives an exit code of 0 iff stdin is connected to a terminal.
-        #
-        # Closing host-side stdin doesn't currently trigger the interactive
-        # shell to exit so we need to explicitly add an exit command to
-        # close the session from the device side, and append \n to complete
-        # the interactive command.
-        result = proc.communicate('[ -t 0 ]; echo x$?; exit 0\n')[0]
-        partition = result.rpartition('x')
-        self.assertEqual(partition[1], 'x')
-        self.assertEqual(int(partition[2]), 0)
-
-        exit_code = self.device.shell_nocheck(['[ -t 0 ]'])[0]
-        self.assertEqual(exit_code, 1)
-
-    def test_shell_protocol(self):
-        """Tests the shell protocol on the device.
-
-        If the device supports shell protocol, this gives us the ability
-        to separate stdout/stderr and return the exit code directly.
-
-        Bug: http://b/19734861
-        """
-        if self.device.SHELL_PROTOCOL_FEATURE not in self.device.features:
-            raise unittest.SkipTest('shell protocol unsupported on this device')
-        result = self.device.shell_nocheck(
-                shlex.split('echo foo; echo bar >&2; exit 17'))
-
-        self.assertEqual(17, result[0])
-        self.assertEqual('foo' + self.device.linesep, result[1])
-        self.assertEqual('bar' + self.device.linesep, result[2])
-
-    def test_non_interactive_sigint(self):
-        """Tests that SIGINT in a non-interactive shell kills the process.
-
-        This requires the shell protocol in order to detect the broken
-        pipe; raw data transfer mode will only see the break once the
-        subprocess tries to read or write.
-
-        Bug: http://b/23825725
-        """
-        if self.device.SHELL_PROTOCOL_FEATURE not in self.device.features:
-            raise unittest.SkipTest('shell protocol unsupported on this device')
-
-        # Start a long-running process.
-        sleep_proc = subprocess.Popen(
-                self.device.adb_cmd + shlex.split('shell echo $$; sleep 60'),
-                stdin=subprocess.PIPE, stdout=subprocess.PIPE,
-                stderr=subprocess.STDOUT)
-        remote_pid = sleep_proc.stdout.readline().strip()
-        self.assertIsNone(sleep_proc.returncode, 'subprocess terminated early')
-        proc_query = shlex.split('ps {0} | grep {0}'.format(remote_pid))
-
-        # Verify that the process is running, send signal, verify it stopped.
-        self.device.shell(proc_query)
-        os.kill(sleep_proc.pid, signal.SIGINT)
-        sleep_proc.communicate()
-        self.assertEqual(1, self.device.shell_nocheck(proc_query)[0],
-                         'subprocess failed to terminate')
-
-
-class ArgumentEscapingTest(DeviceTest):
-    def test_shell_escaping(self):
-        """Make sure that argument escaping is somewhat sane."""
-
-        # http://b/19734868
-        # Note that this actually matches ssh(1)'s behavior --- it's
-        # converted to `sh -c echo hello; echo world` which sh interprets
-        # as `sh -c echo` (with an argument to that shell of "hello"),
-        # and then `echo world` back in the first shell.
-        result = self.device.shell(
-            shlex.split("sh -c 'echo hello; echo world'"))[0]
-        result = result.splitlines()
-        self.assertEqual(['', 'world'], result)
-        # If you really wanted "hello" and "world", here's what you'd do:
-        result = self.device.shell(
-            shlex.split(r'echo hello\;echo world'))[0].splitlines()
-        self.assertEqual(['hello', 'world'], result)
-
-        # http://b/15479704
-        result = self.device.shell(shlex.split("'true && echo t'"))[0].strip()
-        self.assertEqual('t', result)
-        result = self.device.shell(
-            shlex.split("sh -c 'true && echo t'"))[0].strip()
-        self.assertEqual('t', result)
-
-        # http://b/20564385
-        result = self.device.shell(shlex.split('FOO=a BAR=b echo t'))[0].strip()
-        self.assertEqual('t', result)
-        result = self.device.shell(
-            shlex.split(r'echo -n 123\;uname'))[0].strip()
-        self.assertEqual('123Linux', result)
-
-    def test_install_argument_escaping(self):
-        """Make sure that install argument escaping works."""
-        # http://b/20323053
-        tf = tempfile.NamedTemporaryFile('wb', suffix='-text;ls;1.apk',
-                                         delete=False)
-        tf.close()
-        self.assertIn("-text;ls;1.apk", self.device.install(tf.name))
-        os.remove(tf.name)
-
-        # http://b/3090932
-        tf = tempfile.NamedTemporaryFile('wb', suffix="-Live Hold'em.apk",
-                                         delete=False)
-        tf.close()
-        self.assertIn("-Live Hold'em.apk", self.device.install(tf.name))
-        os.remove(tf.name)
-
-
-class RootUnrootTest(DeviceTest):
-    def _test_root(self):
-        message = self.device.root()
-        if 'adbd cannot run as root in production builds' in message:
-            return
-        self.device.wait()
-        self.assertEqual('root', self.device.shell(['id', '-un'])[0].strip())
-
-    def _test_unroot(self):
-        self.device.unroot()
-        self.device.wait()
-        self.assertEqual('shell', self.device.shell(['id', '-un'])[0].strip())
-
-    def test_root_unroot(self):
-        """Make sure that adb root and adb unroot work, using id(1)."""
-        if self.device.get_prop('ro.debuggable') != '1':
-            raise unittest.SkipTest('requires rootable build')
-
-        original_user = self.device.shell(['id', '-un'])[0].strip()
-        try:
-            if original_user == 'root':
-                self._test_unroot()
-                self._test_root()
-            elif original_user == 'shell':
-                self._test_root()
-                self._test_unroot()
-        finally:
-            if original_user == 'root':
-                self.device.root()
-            else:
-                self.device.unroot()
-            self.device.wait()
-
-
-class TcpIpTest(DeviceTest):
-    def test_tcpip_failure_raises(self):
-        """adb tcpip requires a port.
-
-        Bug: http://b/22636927
-        """
-        self.assertRaises(
-            subprocess.CalledProcessError, self.device.tcpip, '')
-        self.assertRaises(
-            subprocess.CalledProcessError, self.device.tcpip, 'foo')
-
-
-class SystemPropertiesTest(DeviceTest):
-    def test_get_prop(self):
-        self.assertEqual(self.device.get_prop('init.svc.adbd'), 'running')
-
-    @requires_root
-    def test_set_prop(self):
-        prop_name = 'foo.bar'
-        self.device.shell(['setprop', prop_name, '""'])
-
-        self.device.set_prop(prop_name, 'qux')
-        self.assertEqual(
-            self.device.shell(['getprop', prop_name])[0].strip(), 'qux')
-
-
-def compute_md5(string):
-    hsh = hashlib.md5()
-    hsh.update(string)
-    return hsh.hexdigest()
-
-
-def get_md5_prog(device):
-    """Older platforms (pre-L) had the name md5 rather than md5sum."""
-    try:
-        device.shell(['md5sum', '/proc/uptime'])
-        return 'md5sum'
-    except subprocess.CalledProcessError:
-        return 'md5'
-
-
-class HostFile(object):
-    def __init__(self, handle, checksum):
-        self.handle = handle
-        self.checksum = checksum
-        self.full_path = handle.name
-        self.base_name = os.path.basename(self.full_path)
-
-
-class DeviceFile(object):
-    def __init__(self, checksum, full_path):
-        self.checksum = checksum
-        self.full_path = full_path
-        self.base_name = posixpath.basename(self.full_path)
-
-
-def make_random_host_files(in_dir, num_files):
-    min_size = 1 * (1 << 10)
-    max_size = 16 * (1 << 10)
-
-    files = []
-    for _ in xrange(num_files):
-        file_handle = tempfile.NamedTemporaryFile(dir=in_dir, delete=False)
-
-        size = random.randrange(min_size, max_size, 1024)
-        rand_str = os.urandom(size)
-        file_handle.write(rand_str)
-        file_handle.flush()
-        file_handle.close()
-
-        md5 = compute_md5(rand_str)
-        files.append(HostFile(file_handle, md5))
-    return files
-
-
-def make_random_device_files(device, in_dir, num_files):
-    min_size = 1 * (1 << 10)
-    max_size = 16 * (1 << 10)
-
-    files = []
-    for file_num in xrange(num_files):
-        size = random.randrange(min_size, max_size, 1024)
-
-        base_name = 'device_tmpfile' + str(file_num)
-        full_path = posixpath.join(in_dir, base_name)
-
-        device.shell(['dd', 'if=/dev/urandom', 'of={}'.format(full_path),
-                      'bs={}'.format(size), 'count=1'])
-        dev_md5, _ = device.shell([get_md5_prog(device), full_path])[0].split()
-
-        files.append(DeviceFile(dev_md5, full_path))
-    return files
-
-
-class FileOperationsTest(DeviceTest):
-    SCRATCH_DIR = '/data/local/tmp'
-    DEVICE_TEMP_FILE = SCRATCH_DIR + '/adb_test_file'
-    DEVICE_TEMP_DIR = SCRATCH_DIR + '/adb_test_dir'
-
-    def _test_push(self, local_file, checksum):
-        self.device.shell(['rm', '-rf', self.DEVICE_TEMP_FILE])
-        self.device.push(local=local_file, remote=self.DEVICE_TEMP_FILE)
-        dev_md5, _ = self.device.shell([get_md5_prog(self.device),
-                                       self.DEVICE_TEMP_FILE])[0].split()
-        self.assertEqual(checksum, dev_md5)
-        self.device.shell(['rm', '-f', self.DEVICE_TEMP_FILE])
-
-    def test_push(self):
-        """Push a randomly generated file to specified device."""
-        kbytes = 512
-        tmp = tempfile.NamedTemporaryFile(mode='wb', delete=False)
-        rand_str = os.urandom(1024 * kbytes)
-        tmp.write(rand_str)
-        tmp.close()
-        self._test_push(tmp.name, compute_md5(rand_str))
-        os.remove(tmp.name)
-
-    # TODO: write push directory test.
-
-    def _test_pull(self, remote_file, checksum):
-        tmp_write = tempfile.NamedTemporaryFile(mode='wb', delete=False)
-        tmp_write.close()
-        self.device.pull(remote=remote_file, local=tmp_write.name)
-        with open(tmp_write.name, 'rb') as tmp_read:
-            host_contents = tmp_read.read()
-            host_md5 = compute_md5(host_contents)
-        self.assertEqual(checksum, host_md5)
-        os.remove(tmp_write.name)
-
-    def test_pull(self):
-        """Pull a randomly generated file from specified device."""
-        kbytes = 512
-        self.device.shell(['rm', '-rf', self.DEVICE_TEMP_FILE])
-        cmd = ['dd', 'if=/dev/urandom',
-               'of={}'.format(self.DEVICE_TEMP_FILE), 'bs=1024',
-               'count={}'.format(kbytes)]
-        self.device.shell(cmd)
-        dev_md5, _ = self.device.shell(
-            [get_md5_prog(self.device), self.DEVICE_TEMP_FILE])[0].split()
-        self._test_pull(self.DEVICE_TEMP_FILE, dev_md5)
-        self.device.shell_nocheck(['rm', self.DEVICE_TEMP_FILE])
-
-    def test_pull_dir(self):
-        """Pull a randomly generated directory of files from the device."""
-        host_dir = tempfile.mkdtemp()
-        self.device.shell(['rm', '-rf', self.DEVICE_TEMP_DIR])
-        self.device.shell(['mkdir', '-p', self.DEVICE_TEMP_DIR])
-
-        # Populate device directory with random files.
-        temp_files = make_random_device_files(
-            self.device, in_dir=self.DEVICE_TEMP_DIR, num_files=32)
-
-        self.device.pull(remote=self.DEVICE_TEMP_DIR, local=host_dir)
-
-        for temp_file in temp_files:
-            host_path = os.path.join(host_dir, temp_file.base_name)
-            with open(host_path, 'rb') as host_file:
-                host_md5 = compute_md5(host_file.read())
-                self.assertEqual(host_md5, temp_file.checksum)
-
-        self.device.shell(['rm', '-rf', self.DEVICE_TEMP_DIR])
-        if host_dir is not None:
-            shutil.rmtree(host_dir)
-
-    def test_sync(self):
-        """Sync a randomly generated directory of files to specified device."""
-        base_dir = tempfile.mkdtemp()
-
-        # Create mirror device directory hierarchy within base_dir.
-        full_dir_path = base_dir + self.DEVICE_TEMP_DIR
-        os.makedirs(full_dir_path)
-
-        # Create 32 random files within the host mirror.
-        temp_files = make_random_host_files(in_dir=full_dir_path, num_files=32)
-
-        # Clean up any trash on the device.
-        device = adb.get_device(product=base_dir)
-        device.shell(['rm', '-rf', self.DEVICE_TEMP_DIR])
-
-        device.sync('data')
-
-        # Confirm that every file on the device mirrors that on the host.
-        for temp_file in temp_files:
-            device_full_path = posixpath.join(self.DEVICE_TEMP_DIR,
-                                              temp_file.base_name)
-            dev_md5, _ = device.shell(
-                [get_md5_prog(self.device), device_full_path])[0].split()
-            self.assertEqual(temp_file.checksum, dev_md5)
-
-        self.device.shell(['rm', '-rf', self.DEVICE_TEMP_DIR])
-        if base_dir is not None:
-            shutil.rmtree(base_dir)
-
-    def test_unicode_paths(self):
-        """Ensure that we can support non-ASCII paths, even on Windows."""
-        name = u'로보카 폴리'
-
-        ## push.
-        tf = tempfile.NamedTemporaryFile('wb', suffix=name, delete=False)
-        tf.close()
-        self.device.push(tf.name, u'/data/local/tmp/adb-test-{}'.format(name))
-        os.remove(tf.name)
-        self.device.shell(['rm', '-f', '/data/local/tmp/adb-test-*'])
-
-        # pull.
-        cmd = ['touch', u'"/data/local/tmp/adb-test-{}"'.format(name)]
-        self.device.shell(cmd)
-
-        tf = tempfile.NamedTemporaryFile('wb', suffix=name, delete=False)
-        tf.close()
-        self.device.pull(u'/data/local/tmp/adb-test-{}'.format(name), tf.name)
-        os.remove(tf.name)
-        self.device.shell(['rm', '-f', '/data/local/tmp/adb-test-*'])
-
-
-def main():
-    random.seed(0)
-    if len(adb.get_devices()) > 0:
-        suite = unittest.TestLoader().loadTestsFromName(__name__)
-        unittest.TextTestRunner(verbosity=3).run(suite)
-    else:
-        print('Test suite must be run with attached devices')
-
-
-if __name__ == '__main__':
-    main()
diff --git a/base/include/base/logging.h b/base/include/base/logging.h
index 283a7bc..30f6906 100644
--- a/base/include/base/logging.h
+++ b/base/include/base/logging.h
@@ -87,30 +87,64 @@
 // Replace the current logger.
 extern void SetLogger(LogFunction&& logger);
 
+// Get the minimum severity level for logging.
+extern LogSeverity GetMinimumLogSeverity();
+
+class ErrnoRestorer {
+ public:
+  ErrnoRestorer()
+      : saved_errno_(errno) {
+  }
+
+  ~ErrnoRestorer() {
+    errno = saved_errno_;
+  }
+
+  // Allow this object to evaluate to false which is useful in macros.
+  operator bool() const {
+    return false;
+  }
+
+ private:
+  const int saved_errno_;
+
+  DISALLOW_COPY_AND_ASSIGN(ErrnoRestorer);
+};
+
 // Logs a message to logcat on Android otherwise to stderr. If the severity is
 // FATAL it also causes an abort. For example:
 //
 //     LOG(FATAL) << "We didn't expect to reach here";
-#define LOG(severity)                                                       \
-  ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::DEFAULT, \
-                              ::android::base::severity, -1).stream()
+#define LOG(severity) LOG_TO(DEFAULT, severity)
 
 // Logs a message to logcat with the specified log ID on Android otherwise to
 // stderr. If the severity is FATAL it also causes an abort.
-#define LOG_TO(dest, severity)                                           \
-  ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::dest, \
-                              ::android::base::severity, -1).stream()
+// Use an if-else statement instead of just an if statement here. So if there is a
+// else statement after LOG() macro, it won't bind to the if statement in the macro.
+// do-while(0) statement doesn't work here. Because we need to support << operator
+// following the macro, like "LOG(DEBUG) << xxx;".
+#define LOG_TO(dest, severity)                                                      \
+  if (LIKELY(::android::base::severity < ::android::base::GetMinimumLogSeverity())) \
+    ;                                                                               \
+  else                                                                              \
+    ::android::base::ErrnoRestorer() ? *(std::ostream*)nullptr :                    \
+      ::android::base::LogMessage(__FILE__, __LINE__,                               \
+          ::android::base::dest,                                                    \
+          ::android::base::severity, -1).stream()
 
 // A variant of LOG that also logs the current errno value. To be used when
 // library calls fail.
-#define PLOG(severity)                                                      \
-  ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::DEFAULT, \
-                              ::android::base::severity, errno).stream()
+#define PLOG(severity) PLOG_TO(DEFAULT, severity)
 
 // Behaves like PLOG, but logs to the specified log ID.
-#define PLOG_TO(dest, severity)                                          \
-  ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::dest, \
-                              ::android::base::severity, errno).stream()
+#define PLOG_TO(dest, severity)                                                     \
+  if (LIKELY(::android::base::severity < ::android::base::GetMinimumLogSeverity())) \
+    ;                                                                               \
+  else                                                                              \
+    ::android::base::ErrnoRestorer() ? *(std::ostream*)nullptr :                    \
+      ::android::base::LogMessage(__FILE__, __LINE__,                               \
+          ::android::base::dest,                                                    \
+          ::android::base::severity, errno).stream()
 
 // Marker that code is yet to be implemented.
 #define UNIMPLEMENTED(level) \
@@ -122,11 +156,13 @@
 //
 //     CHECK(false == true) results in a log message of
 //       "Check failed: false == true".
-#define CHECK(x)                                                            \
-  if (UNLIKELY(!(x)))                                                       \
-  ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::DEFAULT, \
-                              ::android::base::FATAL, -1).stream()          \
-      << "Check failed: " #x << " "
+#define CHECK(x)                                                              \
+  if (LIKELY((x)))                                                            \
+    ;                                                                         \
+  else                                                                        \
+    ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::DEFAULT, \
+                                ::android::base::FATAL, -1).stream()          \
+        << "Check failed: " #x << " "
 
 // Helper for CHECK_xx(x,y) macros.
 #define CHECK_OP(LHS, RHS, OP)                                              \
@@ -153,7 +189,9 @@
 
 // Helper for CHECK_STRxx(s1,s2) macros.
 #define CHECK_STROP(s1, s2, sense)                                         \
-  if (UNLIKELY((strcmp(s1, s2) == 0) != sense))                            \
+  if (LIKELY((strcmp(s1, s2) == 0) == sense))                              \
+    ;                                                                      \
+  else                                                                     \
     LOG(FATAL) << "Check failed: "                                         \
                << "\"" << s1 << "\""                                       \
                << (sense ? " == " : " != ") << "\"" << s2 << "\""
diff --git a/base/logging.cpp b/base/logging.cpp
index e9e06df..6bfaaec 100644
--- a/base/logging.cpp
+++ b/base/logging.cpp
@@ -139,6 +139,10 @@
 static LogSeverity gMinimumLogSeverity = INFO;
 static std::unique_ptr<std::string> gProgramInvocationName;
 
+LogSeverity GetMinimumLogSeverity() {
+  return gMinimumLogSeverity;
+}
+
 static const char* ProgramInvocationName() {
   if (gProgramInvocationName == nullptr) {
     gProgramInvocationName.reset(new std::string(getprogname()));
@@ -200,20 +204,6 @@
   InitLogging(argv);
 }
 
-// TODO: make this public; it's independently useful.
-class ErrnoRestorer {
- public:
-  ErrnoRestorer(int saved_errno) : saved_errno_(saved_errno) {
-  }
-
-  ~ErrnoRestorer() {
-    errno = saved_errno_;
-  }
-
- private:
-  const int saved_errno_;
-};
-
 void InitLogging(char* argv[]) {
   if (gInitialized) {
     return;
@@ -286,13 +276,12 @@
 class LogMessageData {
  public:
   LogMessageData(const char* file, unsigned int line, LogId id,
-                 LogSeverity severity, int error, int saved_errno)
+                 LogSeverity severity, int error)
       : file_(GetFileBasename(file)),
         line_number_(line),
         id_(id),
         severity_(severity),
-        error_(error),
-        errno_restorer_(saved_errno) {
+        error_(error) {
   }
 
   const char* GetFile() const {
@@ -330,39 +319,38 @@
   const LogId id_;
   const LogSeverity severity_;
   const int error_;
-  ErrnoRestorer errno_restorer_;
 
   DISALLOW_COPY_AND_ASSIGN(LogMessageData);
 };
 
 LogMessage::LogMessage(const char* file, unsigned int line, LogId id,
                        LogSeverity severity, int error)
-    : data_(new LogMessageData(file, line, id, severity, error, errno)) {
+    : data_(new LogMessageData(file, line, id, severity, error)) {
 }
 
 LogMessage::~LogMessage() {
-  if (data_->GetSeverity() < gMinimumLogSeverity) {
-    return;  // No need to format something we're not going to output.
-  }
-
   // Finish constructing the message.
   if (data_->GetError() != -1) {
     data_->GetBuffer() << ": " << strerror(data_->GetError());
   }
   std::string msg(data_->ToString());
 
-  if (msg.find('\n') == std::string::npos) {
-    LogLine(data_->GetFile(), data_->GetLineNumber(), data_->GetId(),
-            data_->GetSeverity(), msg.c_str());
-  } else {
-    msg += '\n';
-    size_t i = 0;
-    while (i < msg.size()) {
-      size_t nl = msg.find('\n', i);
-      msg[nl] = '\0';
+  {
+    // Do the actual logging with the lock held.
+    lock_guard<mutex> lock(logging_lock);
+    if (msg.find('\n') == std::string::npos) {
       LogLine(data_->GetFile(), data_->GetLineNumber(), data_->GetId(),
-              data_->GetSeverity(), &msg[i]);
-      i = nl + 1;
+              data_->GetSeverity(), msg.c_str());
+    } else {
+      msg += '\n';
+      size_t i = 0;
+      while (i < msg.size()) {
+        size_t nl = msg.find('\n', i);
+        msg[nl] = '\0';
+        LogLine(data_->GetFile(), data_->GetLineNumber(), data_->GetId(),
+                data_->GetSeverity(), &msg[i]);
+        i = nl + 1;
+      }
     }
   }
 
@@ -382,7 +370,6 @@
 void LogMessage::LogLine(const char* file, unsigned int line, LogId id,
                          LogSeverity severity, const char* message) {
   const char* tag = ProgramInvocationName();
-  lock_guard<mutex> lock(logging_lock);
   gLogger(id, severity, tag, file, line, message);
 }
 
diff --git a/base/logging_test.cpp b/base/logging_test.cpp
index c12dfa5..9cf1aad 100644
--- a/base/logging_test.cpp
+++ b/base/logging_test.cpp
@@ -18,6 +18,10 @@
 
 #include <libgen.h>
 
+#if defined(_WIN32)
+#include <signal.h>
+#endif
+
 #include <regex>
 #include <string>
 
@@ -49,6 +53,11 @@
 
  private:
   void init() {
+#if defined(_WIN32)
+    // On Windows, stderr is often buffered, so make sure it is unbuffered so
+    // that we can immediately read back what was written to stderr.
+    ASSERT_EQ(0, setvbuf(stderr, NULL, _IONBF, 0));
+#endif
     old_stderr_ = dup(STDERR_FILENO);
     ASSERT_NE(-1, old_stderr_);
     ASSERT_NE(-1, dup2(fd(), STDERR_FILENO));
@@ -57,21 +66,58 @@
   void reset() {
     ASSERT_NE(-1, dup2(old_stderr_, STDERR_FILENO));
     ASSERT_EQ(0, close(old_stderr_));
+    // Note: cannot restore prior setvbuf() setting.
   }
 
   TemporaryFile temp_file_;
   int old_stderr_;
 };
 
+#if defined(_WIN32)
+static void ExitSignalAbortHandler(int) {
+  _exit(3);
+}
+#endif
+
+static void SuppressAbortUI() {
+#if defined(_WIN32)
+  // We really just want to call _set_abort_behavior(0, _CALL_REPORTFAULT) to
+  // suppress the Windows Error Reporting dialog box, but that API is not
+  // available in the OS-supplied C Runtime, msvcrt.dll, that we currently
+  // use (it is available in the Visual Studio C runtime).
+  //
+  // Instead, we setup a SIGABRT handler, which is called in abort() right
+  // before calling Windows Error Reporting. In the handler, we exit the
+  // process just like abort() does.
+  ASSERT_NE(SIG_ERR, signal(SIGABRT, ExitSignalAbortHandler));
+#endif
+}
+
 TEST(logging, CHECK) {
-  ASSERT_DEATH(CHECK(false), "Check failed: false ");
+  ASSERT_DEATH({SuppressAbortUI(); CHECK(false);}, "Check failed: false ");
   CHECK(true);
 
-  ASSERT_DEATH(CHECK_EQ(0, 1), "Check failed: 0 == 1 ");
+  ASSERT_DEATH({SuppressAbortUI(); CHECK_EQ(0, 1);}, "Check failed: 0 == 1 ");
   CHECK_EQ(0, 0);
 
-  ASSERT_DEATH(CHECK_STREQ("foo", "bar"), R"(Check failed: "foo" == "bar")");
+  ASSERT_DEATH({SuppressAbortUI(); CHECK_STREQ("foo", "bar");},
+               R"(Check failed: "foo" == "bar")");
   CHECK_STREQ("foo", "foo");
+
+  // Test whether CHECK() and CHECK_STREQ() have a dangling if with no else.
+  bool flag = false;
+  if (true)
+    CHECK(true);
+  else
+    flag = true;
+  EXPECT_FALSE(flag) << "CHECK macro probably has a dangling if with no else";
+
+  flag = false;
+  if (true)
+    CHECK_STREQ("foo", "foo");
+  else
+    flag = true;
+  EXPECT_FALSE(flag) << "CHECK_STREQ probably has a dangling if with no else";
 }
 
 std::string make_log_pattern(android::base::LogSeverity severity,
@@ -85,7 +131,7 @@
 }
 
 TEST(logging, LOG) {
-  ASSERT_DEATH(LOG(FATAL) << "foobar", "foobar");
+  ASSERT_DEATH({SuppressAbortUI(); LOG(FATAL) << "foobar";}, "foobar");
 
   // We can't usefully check the output of any of these on Windows because we
   // don't have std::regex, but we can at least make sure we printed at least as
@@ -148,6 +194,50 @@
     ASSERT_TRUE(std::regex_search(output, message_regex)) << output;
 #endif
   }
+
+  // Test whether LOG() saves and restores errno.
+  {
+    CapturedStderr cap;
+    errno = 12345;
+    LOG(INFO) << (errno = 67890);
+    EXPECT_EQ(12345, errno) << "errno was not restored";
+
+    ASSERT_EQ(0, lseek(cap.fd(), SEEK_SET, 0));
+
+    std::string output;
+    android::base::ReadFdToString(cap.fd(), &output);
+    EXPECT_NE(nullptr, strstr(output.c_str(), "67890")) << output;
+
+#if !defined(_WIN32)
+    std::regex message_regex(
+        make_log_pattern(android::base::INFO, "67890"));
+    ASSERT_TRUE(std::regex_search(output, message_regex)) << output;
+#endif
+  }
+
+  // Test whether LOG() has a dangling if with no else.
+  {
+    CapturedStderr cap;
+
+    // Do the test two ways: once where we hypothesize that LOG()'s if
+    // will evaluate to true (when severity is high enough) and once when we
+    // expect it to evaluate to false (when severity is not high enough).
+    bool flag = false;
+    if (true)
+      LOG(INFO) << "foobar";
+    else
+      flag = true;
+
+    EXPECT_FALSE(flag) << "LOG macro probably has a dangling if with no else";
+
+    flag = false;
+    if (true)
+      LOG(VERBOSE) << "foobar";
+    else
+      flag = true;
+
+    EXPECT_FALSE(flag) << "LOG macro probably has a dangling if with no else";
+  }
 }
 
 TEST(logging, PLOG) {
diff --git a/debuggerd/Android.mk b/debuggerd/Android.mk
index f7a5f82..de0f943 100644
--- a/debuggerd/Android.mk
+++ b/debuggerd/Android.mk
@@ -99,6 +99,7 @@
 debuggerd_cpp_flags := \
     $(common_cppflags) \
     -Wno-missing-field-initializers \
+    -fno-rtti \
 
 # Only build the host tests on linux.
 ifeq ($(HOST_OS),linux)
diff --git a/include/backtrace/Backtrace.h b/include/backtrace/Backtrace.h
index 290682a..f440bd2 100644
--- a/include/backtrace/Backtrace.h
+++ b/include/backtrace/Backtrace.h
@@ -52,6 +52,12 @@
 typedef ucontext ucontext_t;
 #endif
 
+struct backtrace_stackinfo_t {
+  uint64_t start;
+  uint64_t end;
+  const uint8_t* data;
+};
+
 class Backtrace {
 public:
   // Create the correct Backtrace object based on what is to be unwound.
@@ -66,6 +72,14 @@
   // If map is not NULL, the map is still owned by the caller.
   static Backtrace* Create(pid_t pid, pid_t tid, BacktraceMap* map = NULL);
 
+  // Create an offline Backtrace object that can be used to do an unwind without a process
+  // that is still running. If cache_file is set to true, then elf information will be cached
+  // for this call. The cached information survives until the calling process ends. This means
+  // that subsequent calls to create offline Backtrace objects will continue to use the same
+  // cache. It also assumes that the elf files used for each offline unwind are the same.
+  static Backtrace* CreateOffline(pid_t pid, pid_t tid, BacktraceMap* map,
+                                  const backtrace_stackinfo_t& stack, bool cache_file = false);
+
   virtual ~Backtrace();
 
   // Get the current stack trace and store in the backtrace_ structure.
diff --git a/include/backtrace/BacktraceMap.h b/include/backtrace/BacktraceMap.h
index bb18aa2..2373c45 100644
--- a/include/backtrace/BacktraceMap.h
+++ b/include/backtrace/BacktraceMap.h
@@ -31,6 +31,7 @@
 
 #include <deque>
 #include <string>
+#include <vector>
 
 struct backtrace_map_t {
   uintptr_t start = 0;
@@ -48,6 +49,8 @@
   // is unsupported.
   static BacktraceMap* Create(pid_t pid, bool uncached = false);
 
+  static BacktraceMap* Create(pid_t pid, const std::vector<backtrace_map_t>& maps);
+
   virtual ~BacktraceMap();
 
   // Fill in the map data structure for the given address.
diff --git a/libbacktrace/Android.build.mk b/libbacktrace/Android.build.mk
index 4983b55..8e63dab 100644
--- a/libbacktrace/Android.build.mk
+++ b/libbacktrace/Android.build.mk
@@ -69,7 +69,10 @@
     $($(module)_ldlibs) \
     $($(module)_ldlibs_$(build_type)) \
 
+LOCAL_STRIP_MODULE := $($(module)_strip_module)
+
 ifeq ($(build_type),target)
+  include $(LLVM_DEVICE_BUILD_MK)
   include $(BUILD_$(build_target))
 endif
 
@@ -77,6 +80,7 @@
   # Only build if host builds are supported.
   ifeq ($(build_host),true)
     LOCAL_CFLAGS += -Wno-extern-c-compat -fno-omit-frame-pointer
+    include $(LLVM_HOST_BUILD_MK)
     include $(BUILD_HOST_$(build_target))
   endif
 endif
diff --git a/libbacktrace/Android.mk b/libbacktrace/Android.mk
index 395d677..9c6742e 100644
--- a/libbacktrace/Android.mk
+++ b/libbacktrace/Android.mk
@@ -25,6 +25,7 @@
 
 libbacktrace_common_cppflags := \
 	-std=gnu++11 \
+	-I external/libunwind/include/tdep \
 
 # The latest clang (r230699) does not allow SP/PC to be declared in inline asm lists.
 libbacktrace_common_clang_cflags += \
@@ -37,6 +38,9 @@
 endif
 endif
 
+LLVM_ROOT_PATH := external/llvm
+include $(LLVM_ROOT_PATH)/llvm.mk
+
 #-------------------------------------------------------------------------
 # The libbacktrace library.
 #-------------------------------------------------------------------------
@@ -44,6 +48,7 @@
 	Backtrace.cpp \
 	BacktraceCurrent.cpp \
 	BacktraceMap.cpp \
+	BacktraceOffline.cpp \
 	BacktracePtrace.cpp \
 	thread_utils.c \
 	ThreadEntry.cpp \
@@ -56,6 +61,20 @@
 	liblog \
 	libunwind \
 
+# Use shared llvm library on device to save space.
+libbacktrace_shared_libraries_target := \
+	libLLVM \
+
+# Use static llvm libraries on host to remove dependency on 32-bit llvm shared library
+# which is not included in the prebuilt.
+libbacktrace_static_libraries_host := \
+	libLLVMObject \
+	libLLVMBitReader \
+	libLLVMMC \
+	libLLVMMCParser \
+	libLLVMCore \
+	libLLVMSupport \
+
 libbacktrace_ldlibs_host := \
 	-lpthread \
 	-lrt \
@@ -86,6 +105,8 @@
 libbacktrace_test_src_files := \
 	backtrace_testlib.c \
 
+libbacktrace_test_strip_module := false
+
 module := libbacktrace_test
 module_tag := debug
 build_type := target
@@ -107,6 +128,7 @@
 	-DENABLE_PSS_TESTS \
 
 backtrace_test_src_files := \
+	backtrace_offline_test.cpp \
 	backtrace_test.cpp \
 	GetPss.cpp \
 	thread_utils.c \
@@ -120,6 +142,7 @@
 	libbacktrace \
 	libbase \
 	libcutils \
+	libunwind \
 
 backtrace_test_shared_libraries_target += \
 	libdl \
@@ -127,6 +150,8 @@
 backtrace_test_ldlibs_host += \
 	-ldl \
 
+backtrace_test_strip_module := false
+
 module := backtrace_test
 module_tag := debug
 build_type := target
diff --git a/libbacktrace/Backtrace.cpp b/libbacktrace/Backtrace.cpp
index 97f0ef4..9ead452 100644
--- a/libbacktrace/Backtrace.cpp
+++ b/libbacktrace/Backtrace.cpp
@@ -30,6 +30,7 @@
 #include <cutils/threads.h>
 
 #include "BacktraceLog.h"
+#include "BacktraceOffline.h"
 #include "thread_utils.h"
 #include "UnwindCurrent.h"
 #include "UnwindPtrace.h"
@@ -140,3 +141,8 @@
     return new UnwindPtrace(pid, tid, map);
   }
 }
+
+Backtrace* Backtrace::CreateOffline(pid_t pid, pid_t tid, BacktraceMap* map,
+                                    const backtrace_stackinfo_t& stack, bool cache_file) {
+  return new BacktraceOffline(pid, tid, map, stack, cache_file);
+}
diff --git a/libbacktrace/BacktraceMap.cpp b/libbacktrace/BacktraceMap.cpp
index ca47f67..eac20fe 100644
--- a/libbacktrace/BacktraceMap.cpp
+++ b/libbacktrace/BacktraceMap.cpp
@@ -144,3 +144,13 @@
   return map;
 }
 #endif
+
+BacktraceMap* BacktraceMap::Create(pid_t pid, const std::vector<backtrace_map_t>& maps) {
+    BacktraceMap* backtrace_map = new BacktraceMap(pid);
+    backtrace_map->maps_.insert(backtrace_map->maps_.begin(), maps.begin(), maps.end());
+    std::sort(backtrace_map->maps_.begin(), backtrace_map->maps_.end(),
+            [](const backtrace_map_t& map1, const backtrace_map_t& map2) {
+              return map1.start < map2.start;
+            });
+    return backtrace_map;
+}
diff --git a/libbacktrace/BacktraceOffline.cpp b/libbacktrace/BacktraceOffline.cpp
new file mode 100644
index 0000000..27dfb83
--- /dev/null
+++ b/libbacktrace/BacktraceOffline.cpp
@@ -0,0 +1,636 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "BacktraceOffline.h"
+
+extern "C" {
+#define UNW_REMOTE_ONLY
+#include <dwarf.h>
+}
+
+#include <stdint.h>
+#include <string.h>
+#include <sys/types.h>
+#include <ucontext.h>
+#include <unistd.h>
+
+#include <string>
+#include <vector>
+
+#include <backtrace/Backtrace.h>
+#include <backtrace/BacktraceMap.h>
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-parameter"
+
+#include <llvm/ADT/StringRef.h>
+#include <llvm/Object/Binary.h>
+#include <llvm/Object/ELFObjectFile.h>
+#include <llvm/Object/ObjectFile.h>
+
+#pragma clang diagnostic pop
+
+#include "BacktraceLog.h"
+
+void Space::Clear() {
+  start = 0;
+  end = 0;
+  data = nullptr;
+}
+
+size_t Space::Read(uint64_t addr, uint8_t* buffer, size_t size) {
+  if (addr >= start && addr < end) {
+    size_t read_size = std::min(size, static_cast<size_t>(end - addr));
+    memcpy(buffer, data + (addr - start), read_size);
+    return read_size;
+  }
+  return 0;
+}
+
+static int FindProcInfo(unw_addr_space_t addr_space, unw_word_t ip, unw_proc_info* proc_info,
+                        int need_unwind_info, void* arg) {
+  BacktraceOffline* backtrace = reinterpret_cast<BacktraceOffline*>(arg);
+  bool result = backtrace->FindProcInfo(addr_space, ip, proc_info, need_unwind_info);
+  return result ? 0 : -UNW_EINVAL;
+}
+
+static void PutUnwindInfo(unw_addr_space_t, unw_proc_info_t*, void*) {
+}
+
+static int GetDynInfoListAddr(unw_addr_space_t, unw_word_t*, void*) {
+  return -UNW_ENOINFO;
+}
+
+static int AccessMem(unw_addr_space_t, unw_word_t addr, unw_word_t* value, int write, void* arg) {
+  if (write == 1) {
+    return -UNW_EINVAL;
+  }
+  BacktraceOffline* backtrace = reinterpret_cast<BacktraceOffline*>(arg);
+  *value = 0;
+  size_t read_size = backtrace->Read(addr, reinterpret_cast<uint8_t*>(value), sizeof(unw_word_t));
+  // Strictly we should check if read_size matches sizeof(unw_word_t), but it is possible in
+  // .eh_frame_hdr that the section can end at a position not aligned in sizeof(unw_word_t), and
+  // we should permit the read at the end of the section.
+  return (read_size > 0u ? 0 : -UNW_EINVAL);
+}
+
+static int AccessReg(unw_addr_space_t, unw_regnum_t unwind_reg, unw_word_t* value, int write,
+                     void* arg) {
+  if (write == 1) {
+    return -UNW_EINVAL;
+  }
+  BacktraceOffline* backtrace = reinterpret_cast<BacktraceOffline*>(arg);
+  uint64_t reg_value;
+  bool result = backtrace->ReadReg(unwind_reg, &reg_value);
+  if (result) {
+    *value = static_cast<unw_word_t>(reg_value);
+  }
+  return result ? 0 : -UNW_EINVAL;
+}
+
+static int AccessFpReg(unw_addr_space_t, unw_regnum_t, unw_fpreg_t*, int, void*) {
+  return -UNW_EINVAL;
+}
+
+static int Resume(unw_addr_space_t, unw_cursor_t*, void*) {
+  return -UNW_EINVAL;
+}
+
+static int GetProcName(unw_addr_space_t, unw_word_t, char*, size_t, unw_word_t*, void*) {
+  return -UNW_EINVAL;
+}
+
+static unw_accessors_t accessors = {
+    .find_proc_info = FindProcInfo,
+    .put_unwind_info = PutUnwindInfo,
+    .get_dyn_info_list_addr = GetDynInfoListAddr,
+    .access_mem = AccessMem,
+    .access_reg = AccessReg,
+    .access_fpreg = AccessFpReg,
+    .resume = Resume,
+    .get_proc_name = GetProcName,
+};
+
+bool BacktraceOffline::Unwind(size_t num_ignore_frames, ucontext_t* context) {
+  if (context == nullptr) {
+    BACK_LOGW("The context is needed for offline backtracing.");
+    return false;
+  }
+  context_ = context;
+
+  unw_addr_space_t addr_space = unw_create_addr_space(&accessors, 0);
+  unw_cursor_t cursor;
+  int ret = unw_init_remote(&cursor, addr_space, this);
+  if (ret != 0) {
+    BACK_LOGW("unw_init_remote failed %d", ret);
+    unw_destroy_addr_space(addr_space);
+    return false;
+  }
+  size_t num_frames = 0;
+  do {
+    unw_word_t pc;
+    ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);
+    if (ret < 0) {
+      BACK_LOGW("Failed to read IP %d", ret);
+      break;
+    }
+    unw_word_t sp;
+    ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);
+    if (ret < 0) {
+      BACK_LOGW("Failed to read SP %d", ret);
+      break;
+    }
+
+    if (num_ignore_frames == 0) {
+      frames_.resize(num_frames + 1);
+      backtrace_frame_data_t* frame = &frames_[num_frames];
+      frame->num = num_frames;
+      frame->pc = static_cast<uintptr_t>(pc);
+      frame->sp = static_cast<uintptr_t>(sp);
+      frame->stack_size = 0;
+
+      if (num_frames > 0) {
+        backtrace_frame_data_t* prev = &frames_[num_frames - 1];
+        prev->stack_size = frame->sp - prev->sp;
+      }
+      frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
+      FillInMap(frame->pc, &frame->map);
+      num_frames++;
+    } else {
+      num_ignore_frames--;
+    }
+    ret = unw_step(&cursor);
+  } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
+
+  unw_destroy_addr_space(addr_space);
+  context_ = nullptr;
+  return true;
+}
+
+bool BacktraceOffline::ReadWord(uintptr_t ptr, word_t* out_value) {
+  size_t bytes_read = Read(ptr, reinterpret_cast<uint8_t*>(out_value), sizeof(word_t));
+  return bytes_read == sizeof(word_t);
+}
+
+size_t BacktraceOffline::Read(uintptr_t addr, uint8_t* buffer, size_t bytes) {
+  // Normally, libunwind needs stack information and call frame information to do remote unwinding.
+  // If call frame information is stored in .debug_frame, libunwind can read it from file
+  // by itself. If call frame information is stored in .eh_frame, we need to provide data in
+  // .eh_frame/.eh_frame_hdr sections.
+  // The order of readings below doesn't matter, as the spaces don't overlap with each other.
+  size_t read_size = eh_frame_hdr_space_.Read(addr, buffer, bytes);
+  if (read_size != 0) {
+    return read_size;
+  }
+  read_size = eh_frame_space_.Read(addr, buffer, bytes);
+  if (read_size != 0) {
+    return read_size;
+  }
+  read_size = stack_space_.Read(addr, buffer, bytes);
+  return read_size;
+}
+
+static bool FileOffsetToVaddr(
+    const std::vector<DebugFrameInfo::EhFrame::ProgramHeader>& program_headers,
+    uint64_t file_offset, uint64_t* vaddr) {
+  for (auto& header : program_headers) {
+    if (file_offset >= header.file_offset && file_offset < header.file_offset + header.file_size) {
+      // TODO: Consider load_bias?
+      *vaddr = file_offset - header.file_offset + header.vaddr;
+      return true;
+    }
+  }
+  return false;
+}
+
+bool BacktraceOffline::FindProcInfo(unw_addr_space_t addr_space, uint64_t ip,
+                                    unw_proc_info_t* proc_info, int need_unwind_info) {
+  backtrace_map_t map;
+  FillInMap(ip, &map);
+  if (!BacktraceMap::IsValid(map)) {
+    return false;
+  }
+  const std::string& filename = map.name;
+  DebugFrameInfo* debug_frame = GetDebugFrameInFile(filename);
+  if (debug_frame == nullptr) {
+    return false;
+  }
+  if (debug_frame->is_eh_frame) {
+    uint64_t ip_offset = ip - map.start + map.offset;
+    uint64_t ip_vaddr;  // vaddr in the elf file.
+    bool result = FileOffsetToVaddr(debug_frame->eh_frame.program_headers, ip_offset, &ip_vaddr);
+    if (!result) {
+      return false;
+    }
+    // Calculate the addresses where .eh_frame_hdr and .eh_frame stay when the process was running.
+    eh_frame_hdr_space_.start = (ip - ip_vaddr) + debug_frame->eh_frame.eh_frame_hdr_vaddr;
+    eh_frame_hdr_space_.end =
+        eh_frame_hdr_space_.start + debug_frame->eh_frame.eh_frame_hdr_data.size();
+    eh_frame_hdr_space_.data = debug_frame->eh_frame.eh_frame_hdr_data.data();
+
+    eh_frame_space_.start = (ip - ip_vaddr) + debug_frame->eh_frame.eh_frame_vaddr;
+    eh_frame_space_.end = eh_frame_space_.start + debug_frame->eh_frame.eh_frame_data.size();
+    eh_frame_space_.data = debug_frame->eh_frame.eh_frame_data.data();
+
+    unw_dyn_info di;
+    memset(&di, '\0', sizeof(di));
+    di.start_ip = map.start;
+    di.end_ip = map.end;
+    di.format = UNW_INFO_FORMAT_REMOTE_TABLE;
+    di.u.rti.name_ptr = 0;
+    di.u.rti.segbase = eh_frame_hdr_space_.start;
+    di.u.rti.table_data =
+        eh_frame_hdr_space_.start + debug_frame->eh_frame.fde_table_offset_in_eh_frame_hdr;
+    di.u.rti.table_len = (eh_frame_hdr_space_.end - di.u.rti.table_data) / sizeof(unw_word_t);
+    int ret = dwarf_search_unwind_table(addr_space, ip, &di, proc_info, need_unwind_info, this);
+    return ret == 0;
+  }
+
+  eh_frame_hdr_space_.Clear();
+  eh_frame_space_.Clear();
+  unw_dyn_info_t di;
+  unw_word_t segbase = map.start - map.offset;
+  int found = dwarf_find_debug_frame(0, &di, ip, segbase, filename.c_str(), map.start, map.end);
+  if (found == 1) {
+    int ret = dwarf_search_unwind_table(addr_space, ip, &di, proc_info, need_unwind_info, this);
+    return ret == 0;
+  }
+  return false;
+}
+
+bool BacktraceOffline::ReadReg(size_t reg, uint64_t* value) {
+  bool result = true;
+#if defined(__arm__)
+  switch (reg) {
+    case UNW_ARM_R0:
+      *value = context_->uc_mcontext.arm_r0;
+      break;
+    case UNW_ARM_R1:
+      *value = context_->uc_mcontext.arm_r1;
+      break;
+    case UNW_ARM_R2:
+      *value = context_->uc_mcontext.arm_r2;
+      break;
+    case UNW_ARM_R3:
+      *value = context_->uc_mcontext.arm_r3;
+      break;
+    case UNW_ARM_R4:
+      *value = context_->uc_mcontext.arm_r4;
+      break;
+    case UNW_ARM_R5:
+      *value = context_->uc_mcontext.arm_r5;
+      break;
+    case UNW_ARM_R6:
+      *value = context_->uc_mcontext.arm_r6;
+      break;
+    case UNW_ARM_R7:
+      *value = context_->uc_mcontext.arm_r7;
+      break;
+    case UNW_ARM_R8:
+      *value = context_->uc_mcontext.arm_r8;
+      break;
+    case UNW_ARM_R9:
+      *value = context_->uc_mcontext.arm_r9;
+      break;
+    case UNW_ARM_R10:
+      *value = context_->uc_mcontext.arm_r10;
+      break;
+    case UNW_ARM_R11:
+      *value = context_->uc_mcontext.arm_fp;
+      break;
+    case UNW_ARM_R12:
+      *value = context_->uc_mcontext.arm_ip;
+      break;
+    case UNW_ARM_R13:
+      *value = context_->uc_mcontext.arm_sp;
+      break;
+    case UNW_ARM_R14:
+      *value = context_->uc_mcontext.arm_lr;
+      break;
+    case UNW_ARM_R15:
+      *value = context_->uc_mcontext.arm_pc;
+      break;
+    default:
+      result = false;
+  }
+#elif defined(__aarch64__)
+  if (reg <= UNW_AARCH64_PC) {
+    *value = context_->uc_mcontext.regs[reg];
+  } else {
+    result = false;
+  }
+#elif defined(__x86_64__)
+  switch (reg) {
+    case UNW_X86_64_R8:
+      *value = context_->uc_mcontext.gregs[REG_R8];
+      break;
+    case UNW_X86_64_R9:
+      *value = context_->uc_mcontext.gregs[REG_R9];
+      break;
+    case UNW_X86_64_R10:
+      *value = context_->uc_mcontext.gregs[REG_R10];
+      break;
+    case UNW_X86_64_R11:
+      *value = context_->uc_mcontext.gregs[REG_R11];
+      break;
+    case UNW_X86_64_R12:
+      *value = context_->uc_mcontext.gregs[REG_R12];
+      break;
+    case UNW_X86_64_R13:
+      *value = context_->uc_mcontext.gregs[REG_R13];
+      break;
+    case UNW_X86_64_R14:
+      *value = context_->uc_mcontext.gregs[REG_R14];
+      break;
+    case UNW_X86_64_R15:
+      *value = context_->uc_mcontext.gregs[REG_R15];
+      break;
+    case UNW_X86_64_RDI:
+      *value = context_->uc_mcontext.gregs[REG_RDI];
+      break;
+    case UNW_X86_64_RSI:
+      *value = context_->uc_mcontext.gregs[REG_RSI];
+      break;
+    case UNW_X86_64_RBP:
+      *value = context_->uc_mcontext.gregs[REG_RBP];
+      break;
+    case UNW_X86_64_RBX:
+      *value = context_->uc_mcontext.gregs[REG_RBX];
+      break;
+    case UNW_X86_64_RDX:
+      *value = context_->uc_mcontext.gregs[REG_RDX];
+      break;
+    case UNW_X86_64_RAX:
+      *value = context_->uc_mcontext.gregs[REG_RAX];
+      break;
+    case UNW_X86_64_RCX:
+      *value = context_->uc_mcontext.gregs[REG_RCX];
+      break;
+    case UNW_X86_64_RSP:
+      *value = context_->uc_mcontext.gregs[REG_RSP];
+      break;
+    case UNW_X86_64_RIP:
+      *value = context_->uc_mcontext.gregs[REG_RIP];
+      break;
+    default:
+      result = false;
+  }
+#elif defined(__i386__)
+  switch (reg) {
+    case UNW_X86_GS:
+      *value = context_->uc_mcontext.gregs[REG_GS];
+      break;
+    case UNW_X86_FS:
+      *value = context_->uc_mcontext.gregs[REG_FS];
+      break;
+    case UNW_X86_ES:
+      *value = context_->uc_mcontext.gregs[REG_ES];
+      break;
+    case UNW_X86_DS:
+      *value = context_->uc_mcontext.gregs[REG_DS];
+      break;
+    case UNW_X86_EAX:
+      *value = context_->uc_mcontext.gregs[REG_EAX];
+      break;
+    case UNW_X86_EBX:
+      *value = context_->uc_mcontext.gregs[REG_EBX];
+      break;
+    case UNW_X86_ECX:
+      *value = context_->uc_mcontext.gregs[REG_ECX];
+      break;
+    case UNW_X86_EDX:
+      *value = context_->uc_mcontext.gregs[REG_EDX];
+      break;
+    case UNW_X86_ESI:
+      *value = context_->uc_mcontext.gregs[REG_ESI];
+      break;
+    case UNW_X86_EDI:
+      *value = context_->uc_mcontext.gregs[REG_EDI];
+      break;
+    case UNW_X86_EBP:
+      *value = context_->uc_mcontext.gregs[REG_EBP];
+      break;
+    case UNW_X86_EIP:
+      *value = context_->uc_mcontext.gregs[REG_EIP];
+      break;
+    case UNW_X86_ESP:
+      *value = context_->uc_mcontext.gregs[REG_ESP];
+      break;
+    case UNW_X86_TRAPNO:
+      *value = context_->uc_mcontext.gregs[REG_TRAPNO];
+      break;
+    case UNW_X86_CS:
+      *value = context_->uc_mcontext.gregs[REG_CS];
+      break;
+    case UNW_X86_EFLAGS:
+      *value = context_->uc_mcontext.gregs[REG_EFL];
+      break;
+    case UNW_X86_SS:
+      *value = context_->uc_mcontext.gregs[REG_SS];
+      break;
+    default:
+      result = false;
+  }
+#endif
+  return result;
+}
+
+std::string BacktraceOffline::GetFunctionNameRaw(uintptr_t, uintptr_t* offset) {
+  // We don't have enough information to support this. And it is expensive.
+  *offset = 0;
+  return "";
+}
+
+std::unordered_map<std::string, std::unique_ptr<DebugFrameInfo>> BacktraceOffline::debug_frames_;
+std::unordered_set<std::string> BacktraceOffline::debug_frame_missing_files_;
+
+static DebugFrameInfo* ReadDebugFrameFromFile(const std::string& filename);
+
+DebugFrameInfo* BacktraceOffline::GetDebugFrameInFile(const std::string& filename) {
+  if (cache_file_) {
+    auto it = debug_frames_.find(filename);
+    if (it != debug_frames_.end()) {
+      return it->second.get();
+    }
+    if (debug_frame_missing_files_.find(filename) != debug_frame_missing_files_.end()) {
+      return nullptr;
+    }
+  }
+  DebugFrameInfo* debug_frame = ReadDebugFrameFromFile(filename);
+  if (cache_file_) {
+    if (debug_frame != nullptr) {
+      debug_frames_.emplace(filename, std::unique_ptr<DebugFrameInfo>(debug_frame));
+    } else {
+      debug_frame_missing_files_.insert(filename);
+    }
+  } else {
+    if (last_debug_frame_ != nullptr) {
+      delete last_debug_frame_;
+    }
+    last_debug_frame_ = debug_frame;
+  }
+  return debug_frame;
+}
+
+static bool OmitEncodedValue(uint8_t encode, const uint8_t*& p) {
+  if (encode == DW_EH_PE_omit) {
+    return 0;
+  }
+  uint8_t format = encode & 0x0f;
+  switch (format) {
+    case DW_EH_PE_ptr:
+      p += sizeof(unw_word_t);
+      break;
+    case DW_EH_PE_uleb128:
+    case DW_EH_PE_sleb128:
+      while ((*p & 0x80) != 0) {
+        ++p;
+      }
+      ++p;
+      break;
+    case DW_EH_PE_udata2:
+    case DW_EH_PE_sdata2:
+      p += 2;
+      break;
+    case DW_EH_PE_udata4:
+    case DW_EH_PE_sdata4:
+      p += 4;
+      break;
+    case DW_EH_PE_udata8:
+    case DW_EH_PE_sdata8:
+      p += 8;
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+
+static bool GetFdeTableOffsetInEhFrameHdr(const std::vector<uint8_t>& data,
+                                          uint64_t* table_offset_in_eh_frame_hdr) {
+  const uint8_t* p = data.data();
+  const uint8_t* end = p + data.size();
+  if (p + 4 > end) {
+    return false;
+  }
+  uint8_t version = *p++;
+  if (version != 1) {
+    return false;
+  }
+  uint8_t eh_frame_ptr_encode = *p++;
+  uint8_t fde_count_encode = *p++;
+  uint8_t fde_table_encode = *p++;
+
+  if (fde_table_encode != (DW_EH_PE_datarel | DW_EH_PE_sdata4)) {
+    return false;
+  }
+
+  if (!OmitEncodedValue(eh_frame_ptr_encode, p) || !OmitEncodedValue(fde_count_encode, p)) {
+    return false;
+  }
+  if (p >= end) {
+    return false;
+  }
+  *table_offset_in_eh_frame_hdr = p - data.data();
+  return true;
+}
+
+using ProgramHeader = DebugFrameInfo::EhFrame::ProgramHeader;
+
+template <class ELFT>
+DebugFrameInfo* ReadDebugFrameFromELFFile(const llvm::object::ELFFile<ELFT>* elf) {
+  bool has_eh_frame_hdr = false;
+  uint64_t eh_frame_hdr_vaddr = 0;
+  std::vector<uint8_t> eh_frame_hdr_data;
+  bool has_eh_frame = false;
+  uint64_t eh_frame_vaddr = 0;
+  std::vector<uint8_t> eh_frame_data;
+
+  for (auto it = elf->begin_sections(); it != elf->end_sections(); ++it) {
+    llvm::ErrorOr<llvm::StringRef> name = elf->getSectionName(&*it);
+    if (name) {
+      if (name.get() == ".debug_frame") {
+        DebugFrameInfo* debug_frame = new DebugFrameInfo;
+        debug_frame->is_eh_frame = false;
+        return debug_frame;
+      }
+      if (name.get() == ".eh_frame_hdr") {
+        has_eh_frame_hdr = true;
+        eh_frame_hdr_vaddr = it->sh_addr;
+        llvm::ErrorOr<llvm::ArrayRef<uint8_t>> data = elf->getSectionContents(&*it);
+        if (data) {
+          eh_frame_hdr_data.insert(eh_frame_hdr_data.begin(), data->data(),
+                                   data->data() + data->size());
+        } else {
+          return nullptr;
+        }
+      } else if (name.get() == ".eh_frame") {
+        has_eh_frame = true;
+        eh_frame_vaddr = it->sh_addr;
+        llvm::ErrorOr<llvm::ArrayRef<uint8_t>> data = elf->getSectionContents(&*it);
+        if (data) {
+          eh_frame_data.insert(eh_frame_data.begin(), data->data(), data->data() + data->size());
+        } else {
+          return nullptr;
+        }
+      }
+    }
+  }
+  if (!(has_eh_frame_hdr && has_eh_frame)) {
+    return nullptr;
+  }
+  uint64_t fde_table_offset;
+  if (!GetFdeTableOffsetInEhFrameHdr(eh_frame_hdr_data, &fde_table_offset)) {
+    return nullptr;
+  }
+
+  std::vector<ProgramHeader> program_headers;
+  for (auto it = elf->begin_program_headers(); it != elf->end_program_headers(); ++it) {
+    ProgramHeader header;
+    header.vaddr = it->p_vaddr;
+    header.file_offset = it->p_offset;
+    header.file_size = it->p_filesz;
+    program_headers.push_back(header);
+  }
+  DebugFrameInfo* debug_frame = new DebugFrameInfo;
+  debug_frame->is_eh_frame = true;
+  debug_frame->eh_frame.eh_frame_hdr_vaddr = eh_frame_hdr_vaddr;
+  debug_frame->eh_frame.eh_frame_vaddr = eh_frame_vaddr;
+  debug_frame->eh_frame.fde_table_offset_in_eh_frame_hdr = fde_table_offset;
+  debug_frame->eh_frame.eh_frame_hdr_data = std::move(eh_frame_hdr_data);
+  debug_frame->eh_frame.eh_frame_data = std::move(eh_frame_data);
+  debug_frame->eh_frame.program_headers = program_headers;
+  return debug_frame;
+}
+
+static DebugFrameInfo* ReadDebugFrameFromFile(const std::string& filename) {
+  auto owning_binary = llvm::object::createBinary(llvm::StringRef(filename));
+  if (owning_binary.getError()) {
+    return nullptr;
+  }
+  llvm::object::Binary* binary = owning_binary.get().getBinary();
+  auto obj = llvm::dyn_cast<llvm::object::ObjectFile>(binary);
+  if (obj == nullptr) {
+    return nullptr;
+  }
+  if (auto elf = llvm::dyn_cast<llvm::object::ELF32LEObjectFile>(obj)) {
+    return ReadDebugFrameFromELFFile(elf->getELFFile());
+  }
+  if (auto elf = llvm::dyn_cast<llvm::object::ELF64LEObjectFile>(obj)) {
+    return ReadDebugFrameFromELFFile(elf->getELFFile());
+  }
+  return nullptr;
+}
diff --git a/libbacktrace/BacktraceOffline.h b/libbacktrace/BacktraceOffline.h
new file mode 100644
index 0000000..42f826d
--- /dev/null
+++ b/libbacktrace/BacktraceOffline.h
@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _LIBBACKTRACE_UNWIND_OFFLINE_H
+#define _LIBBACKTRACE_UNWIND_OFFLINE_H
+
+#include <libunwind.h>
+#include <stdint.h>
+#include <sys/types.h>
+#include <ucontext.h>
+
+#include <unordered_map>
+#include <unordered_set>
+
+#include <backtrace/Backtrace.h>
+
+struct Space {
+  uint64_t start;
+  uint64_t end;
+  const uint8_t* data;
+
+  Space() {
+    Clear();
+  }
+
+  void Clear();
+  size_t Read(uint64_t addr, uint8_t* buffer, size_t size);
+};
+
+struct DebugFrameInfo {
+  bool is_eh_frame;
+  struct EhFrame {
+    uint64_t eh_frame_hdr_vaddr;
+    uint64_t eh_frame_vaddr;
+    uint64_t fde_table_offset_in_eh_frame_hdr;
+    std::vector<uint8_t> eh_frame_hdr_data;
+    std::vector<uint8_t> eh_frame_data;
+    struct ProgramHeader {
+      uint64_t vaddr;
+      uint64_t file_offset;
+      uint64_t file_size;
+    };
+    std::vector<ProgramHeader> program_headers;
+  } eh_frame;
+};
+
+class BacktraceOffline : public Backtrace {
+ public:
+  BacktraceOffline(pid_t pid, pid_t tid, BacktraceMap* map, const backtrace_stackinfo_t& stack,
+                   bool cache_file)
+      : Backtrace(pid, tid, map),
+        cache_file_(cache_file),
+        context_(nullptr),
+        last_debug_frame_(nullptr) {
+    stack_space_.start = stack.start;
+    stack_space_.end = stack.end;
+    stack_space_.data = stack.data;
+  }
+
+  virtual ~BacktraceOffline() {
+    if (last_debug_frame_ != nullptr) {
+      delete last_debug_frame_;
+    }
+  }
+
+  bool Unwind(size_t num_ignore_frames, ucontext_t* context) override;
+
+  bool ReadWord(uintptr_t ptr, word_t* out_value) override;
+
+  size_t Read(uintptr_t addr, uint8_t* buffer, size_t bytes) override;
+
+  bool FindProcInfo(unw_addr_space_t addr_space, uint64_t ip, unw_proc_info_t* proc_info,
+                    int need_unwind_info);
+
+  bool ReadReg(size_t reg_index, uint64_t* value);
+
+ protected:
+  std::string GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) override;
+  DebugFrameInfo* GetDebugFrameInFile(const std::string& filename);
+
+  static std::unordered_map<std::string, std::unique_ptr<DebugFrameInfo>> debug_frames_;
+  static std::unordered_set<std::string> debug_frame_missing_files_;
+
+  bool cache_file_;
+  ucontext_t* context_;
+  Space eh_frame_hdr_space_;
+  Space eh_frame_space_;
+  Space stack_space_;
+  DebugFrameInfo* last_debug_frame_;
+};
+
+#endif  // _LIBBACKTRACE_BACKTRACE_OFFLINE_H
diff --git a/libbacktrace/backtrace_offline_test.cpp b/libbacktrace/backtrace_offline_test.cpp
new file mode 100644
index 0000000..88a3533
--- /dev/null
+++ b/libbacktrace/backtrace_offline_test.cpp
@@ -0,0 +1,189 @@
+#include <libunwind.h>
+#include <pthread.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <functional>
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <backtrace/Backtrace.h>
+#include <backtrace/BacktraceMap.h>
+#include <cutils/threads.h>
+
+#include <gtest/gtest.h>
+
+extern "C" {
+// Prototypes for functions in the test library.
+int test_level_one(int, int, int, int, void (*)(void*), void*);
+int test_level_two(int, int, int, int, void (*)(void*), void*);
+int test_level_three(int, int, int, int, void (*)(void*), void*);
+int test_level_four(int, int, int, int, void (*)(void*), void*);
+int test_recursive_call(int, void (*)(void*), void*);
+}
+
+static volatile bool g_exit_flag = false;
+
+static void GetContextAndExit(void* arg) {
+  unw_context_t* unw_context = reinterpret_cast<unw_context_t*>(arg);
+  unw_getcontext(unw_context);
+  // Don't touch the stack anymore.
+  while (!g_exit_flag) {
+  }
+}
+
+struct OfflineThreadArg {
+  unw_context_t unw_context;
+  pid_t tid;
+  std::function<int(void (*)(void*), void*)> function;
+};
+
+static void* OfflineThreadFunc(void* arg) {
+  OfflineThreadArg* fn_arg = reinterpret_cast<OfflineThreadArg*>(arg);
+  fn_arg->tid = gettid();
+  fn_arg->function(GetContextAndExit, &fn_arg->unw_context);
+  return nullptr;
+}
+
+static ucontext_t GetUContextFromUnwContext(const unw_context_t& unw_context) {
+  ucontext_t ucontext;
+  memset(&ucontext, 0, sizeof(ucontext));
+#if defined(__arm__)
+  ucontext.uc_mcontext.arm_r0 = unw_context.regs[0];
+  ucontext.uc_mcontext.arm_r1 = unw_context.regs[1];
+  ucontext.uc_mcontext.arm_r2 = unw_context.regs[2];
+  ucontext.uc_mcontext.arm_r3 = unw_context.regs[3];
+  ucontext.uc_mcontext.arm_r4 = unw_context.regs[4];
+  ucontext.uc_mcontext.arm_r5 = unw_context.regs[5];
+  ucontext.uc_mcontext.arm_r6 = unw_context.regs[6];
+  ucontext.uc_mcontext.arm_r7 = unw_context.regs[7];
+  ucontext.uc_mcontext.arm_r8 = unw_context.regs[8];
+  ucontext.uc_mcontext.arm_r9 = unw_context.regs[9];
+  ucontext.uc_mcontext.arm_r10 = unw_context.regs[10];
+  ucontext.uc_mcontext.arm_fp = unw_context.regs[11];
+  ucontext.uc_mcontext.arm_ip = unw_context.regs[12];
+  ucontext.uc_mcontext.arm_sp = unw_context.regs[13];
+  ucontext.uc_mcontext.arm_lr = unw_context.regs[14];
+  ucontext.uc_mcontext.arm_pc = unw_context.regs[15];
+#else
+  ucontext.uc_mcontext = unw_context.uc_mcontext;
+#endif
+  return ucontext;
+}
+
+static void OfflineBacktraceFunctionCall(std::function<int(void (*)(void*), void*)> function,
+                                         std::vector<uintptr_t>* pc_values) {
+  // Create a thread to generate the needed stack and registers information.
+  g_exit_flag = false;
+  const size_t stack_size = 1024 * 1024;
+  void* stack = mmap(NULL, stack_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  ASSERT_NE(MAP_FAILED, stack);
+  uintptr_t stack_addr = reinterpret_cast<uintptr_t>(stack);
+  pthread_attr_t attr;
+  ASSERT_EQ(0, pthread_attr_init(&attr));
+  ASSERT_EQ(0, pthread_attr_setstack(&attr, reinterpret_cast<void*>(stack), stack_size));
+  pthread_t thread;
+  OfflineThreadArg arg;
+  arg.function = function;
+  ASSERT_EQ(0, pthread_create(&thread, &attr, OfflineThreadFunc, &arg));
+  // Wait for the offline thread to generate the stack and unw_context information.
+  sleep(1);
+  // Copy the stack information.
+  std::vector<uint8_t> stack_data(reinterpret_cast<uint8_t*>(stack),
+                                  reinterpret_cast<uint8_t*>(stack) + stack_size);
+  g_exit_flag = true;
+  ASSERT_EQ(0, pthread_join(thread, nullptr));
+  ASSERT_EQ(0, munmap(stack, stack_size));
+
+  // Do offline backtrace.
+  std::unique_ptr<BacktraceMap> map(BacktraceMap::Create(getpid()));
+  ASSERT_TRUE(map != nullptr);
+
+  backtrace_stackinfo_t stack_info;
+  stack_info.start = stack_addr;
+  stack_info.end = stack_addr + stack_size;
+  stack_info.data = stack_data.data();
+
+  std::unique_ptr<Backtrace> backtrace(
+      Backtrace::CreateOffline(getpid(), arg.tid, map.get(), stack_info));
+  ASSERT_TRUE(backtrace != nullptr);
+
+  ucontext_t ucontext = GetUContextFromUnwContext(arg.unw_context);
+  ASSERT_TRUE(backtrace->Unwind(0, &ucontext));
+
+  // Collect pc values of the call stack frames.
+  for (size_t i = 0; i < backtrace->NumFrames(); ++i) {
+    pc_values->push_back(backtrace->GetFrame(i)->pc);
+  }
+}
+
+// Return the name of the function which matches the address. Although we don't know the
+// exact end of each function, it is accurate enough for the tests.
+static std::string FunctionNameForAddress(uintptr_t addr) {
+  struct FunctionSymbol {
+    std::string name;
+    uintptr_t start;
+    uintptr_t end;
+  };
+
+  static std::vector<FunctionSymbol> symbols;
+  if (symbols.empty()) {
+    symbols = std::vector<FunctionSymbol>{
+        {"unknown_start", 0, 0},
+        {"test_level_one", reinterpret_cast<uintptr_t>(&test_level_one), 0},
+        {"test_level_two", reinterpret_cast<uintptr_t>(&test_level_two), 0},
+        {"test_level_three", reinterpret_cast<uintptr_t>(&test_level_three), 0},
+        {"test_level_four", reinterpret_cast<uintptr_t>(&test_level_four), 0},
+        {"test_recursive_call", reinterpret_cast<uintptr_t>(&test_recursive_call), 0},
+        {"GetContextAndExit", reinterpret_cast<uintptr_t>(&GetContextAndExit), 0},
+        {"unknown_end", static_cast<uintptr_t>(-1), static_cast<uintptr_t>(-1)},
+    };
+    std::sort(
+        symbols.begin(), symbols.end(),
+        [](const FunctionSymbol& s1, const FunctionSymbol& s2) { return s1.start < s2.start; });
+    for (size_t i = 0; i + 1 < symbols.size(); ++i) {
+      symbols[i].end = symbols[i + 1].start;
+    }
+  }
+  for (auto& symbol : symbols) {
+    if (addr >= symbol.start && addr < symbol.end) {
+      return symbol.name;
+    }
+  }
+  return "";
+}
+
+TEST(libbacktrace, offline) {
+  std::function<int(void (*)(void*), void*)> function =
+      std::bind(test_level_one, 1, 2, 3, 4, std::placeholders::_1, std::placeholders::_2);
+  std::vector<uintptr_t> pc_values;
+  OfflineBacktraceFunctionCall(function, &pc_values);
+  ASSERT_FALSE(pc_values.empty());
+  ASSERT_LE(pc_values.size(), static_cast<size_t>(MAX_BACKTRACE_FRAMES));
+
+  size_t test_one_index = 0;
+  for (size_t i = 0; i < pc_values.size(); ++i) {
+    if (FunctionNameForAddress(pc_values[i]) == "test_level_one") {
+      test_one_index = i;
+      break;
+    }
+  }
+
+  ASSERT_GE(test_one_index, 3u);
+  ASSERT_EQ("test_level_one", FunctionNameForAddress(pc_values[test_one_index]));
+  ASSERT_EQ("test_level_two", FunctionNameForAddress(pc_values[test_one_index - 1]));
+  ASSERT_EQ("test_level_three", FunctionNameForAddress(pc_values[test_one_index - 2]));
+  ASSERT_EQ("test_level_four", FunctionNameForAddress(pc_values[test_one_index - 3]));
+}
+
+TEST(libbacktrace, offline_max_trace) {
+  std::function<int(void (*)(void*), void*)> function = std::bind(
+      test_recursive_call, MAX_BACKTRACE_FRAMES + 10, std::placeholders::_1, std::placeholders::_2);
+  std::vector<uintptr_t> pc_values;
+  OfflineBacktraceFunctionCall(function, &pc_values);
+  ASSERT_FALSE(pc_values.empty());
+  ASSERT_EQ(static_cast<size_t>(MAX_BACKTRACE_FRAMES), pc_values.size());
+  ASSERT_EQ("test_recursive_call", FunctionNameForAddress(pc_values.back()));
+}