# Copyright 2014 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Connect to a DUT in firmware via remote GDB, install custom GDB commands."""

from __future__ import print_function

import errno
import logging
import os
import re
import signal
import socket
import time

from chromite.cbuildbot import constants
from chromite.lib import commandline
from chromite.lib import cros_build_lib
from chromite.lib import osutils
from chromite.lib import timeout_util

# pylint: disable=W0622
from chromite.lib.cros_build_lib import Error, Warning, Info, Debug

# Need to do this before Servo import
cros_build_lib.AssertInsideChroot()

# pylint: disable=import-error
from servo import client
from servo import multiservo
# pylint: enable=import-error

_SRC_ROOT = os.path.join(constants.CHROOT_SOURCE_ROOT, 'src')
_SRC_DC = os.path.join(_SRC_ROOT, 'platform/depthcharge')
_SRC_VB = os.path.join(_SRC_ROOT, 'platform/vboot_reference')
_SRC_LP = os.path.join(_SRC_ROOT, 'third_party/coreboot/payloads/libpayload')

_PTRN_DEVMODE = 'Entering VbBootDeveloper()'
_PTRN_GDB = 'Ready for GDB connection'
_PTRN_BOARD = 'Starting(?: read-only| read/write)? depthcharge on ([a-z_]+)...'


class TerminalFreezer(object):
  """SIGSTOP all processes (and their parents) that have the TTY open."""

  def __init__(self, tty):
    self._tty = tty
    self._processes = None
    if 'cros_sdk' in osutils.ReadFile('/proc/1/cmdline'):
      raise OSError('You must run this tool in a chroot that was entered with '
                    '"cros_sdk --no-ns-pid" (see crbug.com/444931 for details)')

  def __enter__(self):
    lsof = cros_build_lib.RunCommand(
        ['lsof', '-FR', self._tty],
        capture_output=True, log_output=True, error_code_ok=True)
    self._processes = re.findall(r'^(?:R|p)(\d+)$', lsof.output, re.MULTILINE)

    # SIGSTOP parents before children
    try:
      for p in reversed(self._processes):
        Info('Sending SIGSTOP to process %s!', p)
        time.sleep(0.02)
        os.kill(int(p), signal.SIGSTOP)
    except OSError:
      self.__exit__(None, None, None)
      raise

  def __exit__(self, _t, _v, _b):
    # ...and wake 'em up again in reverse order
    for p in self._processes:
      Info('Sending SIGCONT to process %s!', p)
      try:
        os.kill(int(p), signal.SIGCONT)
      except OSError as e:
        Error('Error when trying to unfreeze process %s: %s' % (p, str(e)))


def ParsePortage(board):
  """Parse some data from portage files. equery takes ages in comparison."""
  with open(os.path.join('/build', board, 'packages/Packages'), 'r') as f:
    chost = None
    use = None
    for line in f:
      if line[:7] == 'CHOST: ':
        chost = line[7:].strip()
      if line[:5] == 'USE: ':
        use = line[5:].strip()
      if chost and use:
        return (chost, use)


def ParseArgs(argv):
  """Parse and validate command line arguments."""
  parser = commandline.ArgumentParser(default_log_level='warning')

  parser.add_argument('-b', '--board',
                      help='The board overlay name (auto-detect by default)')
  parser.add_argument('-s', '--symbols',
                      help='Root directory or complete path to symbolized ELF '
                           '(defaults to /build/<BOARD>/firmware)')
  parser.add_argument('-r', '--reboot', choices=['yes', 'no', 'auto'],
                      help='Reboot the DUT before connect (default: reboot if '
                           'the remote and is unreachable)', default='auto')
  parser.add_argument('-e', '--execute', action='append', default=[],
                      help='GDB command to run after connect (can be supplied '
                           'multiple times)')

  parser.add_argument('-n', '--servod-name', dest='name')
  parser.add_argument('--servod-rcfile', default=multiservo.DEFAULT_RC_FILE)
  parser.add_argument('--servod-server')
  parser.add_argument('-p', '--servod-port', type=int, dest='port')
  parser.add_argument('-t', '--tty',
                      help='TTY file to connect to (defaults to cpu_uart_pty)')

  opts = parser.parse_args(argv)
  multiservo.get_env_options(logging, opts)
  if opts.name:
    rc = multiservo.parse_rc(logging, opts.servod_rcfile)
    if opts.name not in rc:
      raise parser.error('%s not in %s' % (opts.name, opts.servod_rcfile))
    if not opts.servod_server:
      opts.servod_server = rc[opts.name]['sn']
    if not opts.port:
      opts.port = rc[opts.name].get('port', client.DEFAULT_PORT)
    if not opts.board and 'board' in rc[opts.name]:
      opts.board = rc[opts.name]['board']
      Warning('Inferring board %s from %s... make sure this is correct!',
              opts.board, opts.servod_rcfile)

  if not opts.servod_server:
    opts.servod_server = client.DEFAULT_HOST
  if not opts.port:
    opts.port = client.DEFAULT_PORT

  return opts


def FindSymbols(firmware_dir, board, use):
  """Find the symbolized depthcharge ELF (may be supplied by -s flag)."""
  if not firmware_dir:
    firmware_dir = os.path.join(cros_build_lib.GetSysroot(board), 'firmware')
  # Allow overriding the file directly just in case our detection screws up
  if firmware_dir.endswith('.elf'):
    return firmware_dir

  if 'unified_depthcharge' in use:
    basename = 'dev.elf'
  else:
    basename = 'dev.ro.elf'

  path = os.path.join(firmware_dir, 'depthcharge', basename)
  if not os.path.exists(path):
    path = os.path.join(firmware_dir, basename)

  if os.path.exists(path):
    Warning('Auto-detected symbol file at %s... make sure that this matches '
            'the image on your DUT!', path)
    return path

  raise ValueError('Could not find %s symbol file!' % basename)


# TODO(jwerner): Fine tune |wait| delay or maybe even make it configurable if
# this causes problems due to load on the host. The callers where this is
# critical should all have their own timeouts now, though, so it's questionable
# whether the delay here is even needed at all anymore.
def ReadAll(fd, wait=0.03):
  """Read from |fd| until no more data has come for at least |wait| seconds."""
  data = ''
  try:
    while True:
      time.sleep(wait)
      data += os.read(fd, 4096)
  except OSError as e:
    if e.errno == errno.EAGAIN:
      Debug(data)
      return data
    raise


def GdbChecksum(message):
  """Calculate a remote-GDB style checksum."""
  chksum = sum([ord(x) for x in message])
  return ('%.2x' % chksum)[-2:]


def TestConnection(fd):
  """Return True iff there is a resposive GDB stub on the other end of 'fd'."""
  cmd = 'vUnknownCommand'
  for _ in xrange(3):
    os.write(fd, '$%s#%s\n' % (cmd, GdbChecksum(cmd)))
    reply = ReadAll(fd)
    if '+$#00' in reply:
      os.write(fd, '+')
      Info('TestConnection: Could successfully connect to remote end.')
      return True
  Info('TestConnection: Remote end does not respond.')
  return False


def main(argv):
  opts = ParseArgs(argv)
  servo = client.ServoClient(host=opts.servod_server, port=opts.port)

  if not opts.tty:
    try:
      opts.tty = servo.get('cpu_uart_pty')
    except (client.ServoClientError, socket.error):
      Error('Cannot auto-detect TTY file without servod. Use the --tty option.')
      raise
  with TerminalFreezer(opts.tty):
    fd = os.open(opts.tty, os.O_RDWR | os.O_NONBLOCK)

    data = ReadAll(fd)
    if opts.reboot == 'auto':
      if TestConnection(fd):
        opts.reboot = 'no'
      else:
        opts.reboot = 'yes'

    if opts.reboot == 'yes':
      Info('Rebooting DUT...')
      try:
        servo.set('warm_reset', 'on')
        time.sleep(0.1)
        servo.set('warm_reset', 'off')
      except (client.ServoClientError, socket.error):
        Error('Cannot reboot without a Servo board. You have to boot into '
              'developer mode and press CTRL+G manually before running fwgdb.')
        raise

      # Throw away old data to avoid confusion from messages before the reboot
      data = ''
      msg = ('Could not reboot into developer mode! '
             '(Confirm that you have GBB_FLAG_FORCE_DEV_SWITCH_ON (0x8) set.)')
      with timeout_util.Timeout(10, msg):
        while _PTRN_DEVMODE not in data:
          data += ReadAll(fd)

      # Send a CTRL+G
      Info('Developer mode detected, pressing CTRL+G...')
      os.write(fd, chr(ord('G') & 0x1f))

      msg = ('Could not enter GDB mode with CTRL+G! '
             '(Confirm that you flashed an "image.dev.bin" image to this DUT.)')
      with timeout_util.Timeout(1, msg):
        while _PTRN_GDB not in data:
          data += ReadAll(fd)

    if not opts.board:
      matches = re.findall(_PTRN_BOARD, data)
      if not matches:
        raise ValueError('Could not auto-detect board! Please use -b option.')
      opts.board = matches[-1]
      Info('Auto-detected board as %s from DUT console output.', opts.board)

    if not TestConnection(fd):
      raise IOError('Could not connect to remote end! Confirm that your DUT is '
                    'running in GDB mode on %s.' % opts.tty)

    # Eat up leftover data or it will spill back to terminal
    ReadAll(fd)
    os.close(fd)

    opts.execute.insert(0, 'target remote %s' % opts.tty)
    ex_args = sum([['--ex', cmd] for cmd in opts.execute], [])

    chost, use = ParsePortage(opts.board)
    Info('Launching GDB...')
    cros_build_lib.RunCommand(
        [chost + '-gdb',
         '--symbols', FindSymbols(opts.symbols, opts.board, use),
         '--directory', _SRC_DC,
         '--directory', _SRC_VB,
         '--directory', _SRC_LP] + ex_args,
        ignore_sigint=True, debug_level=logging.WARNING)