host/gdb_remote

#!/bin/bash

# Copyright (c) 2011 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.

. /usr/lib/crosutils/common.sh || exit 1

# Flags
DEFINE_string attach "" \
 "pgrep for the given command - 'browser' finds the chrome browser process"
DEFINE_string board "${DEFAULT_BOARD}" \
 "The board to run debugger on."
DEFINE_string remote "localhost" \
 "The IP address of the remote device."
DEFINE_integer port 1234 \
 "The port number to use for connecting to remote device."
DEFINE_integer remote_pid 0 \
 "Process ID of the running process on the remote device to which to attach."
DEFINE_string remote_file "" \
 "Full pathname of the file to be debugged on the remote device."

# Parse command line
FLAGS_HELP="usage: $0 [flags]"
FLAGS "$@" || exit 1
eval set -- "${FLAGS_ARGV}"
check_flags_only_and_allow_null_arg "$@" && set --

BOARD=${FLAGS_board}
BOARD_ROOT=/build/${BOARD}

# Derive toolchain from $BOARD
CHOST=$(portageq-${BOARD} envvar CHOST)

TMP_DIR=""
SSH_PID=0
CLEAN=0
GDBINIT_FILE=~/.gdbinit

cleanup ()
{
  if [ ${CLEAN} -eq 0 ] ; then
    rm -rf ${TMP_DIR}
    if [ ${SSH_PID} -ne 0 ] ; then
      kill ${SSH_PID}
    fi
    CLEAN=1
  fi
  rm -rf ${GDBINIT_FILE}
}

# Create a temporary location in which to copy testing_rsa file; make
# sure to clean it up when we exit.

trap 'cleanup' EXIT INT TERM
TMP_DIR=$(mktemp -d)

cp ${SCRIPTS_DIR}/mod_for_test_scripts/ssh_keys/testing_rsa \
 ${TMP_DIR}/testing_rsa
chmod 0600 ${TMP_DIR}/testing_rsa

REMOTE_SSH_FLAGS=" -o StrictHostKeyChecking=no -o CheckHostIP=no\
 -o BatchMode=yes"

run_remote_command ()
{
  ssh -i ${TMP_DIR}/testing_rsa \
    ${REMOTE_SSH_FLAGS} root@${FLAGS_remote} ${VM_PORT} \
    "$@"
}

ssh_to_remote_machine ()
{
  local command=$1
  local error_msg=$2

  if ! run_remote_command "${command}" ; then
     die "${error_msg}"
  fi
}

validate_command_options ()
{
  # Verify we have at least a board, toolchain and remote file.

  if [[ -z "${BOARD}" ]] ; then
    die "--board is required."
  fi

  if [[ -z "${CHOST}" ]] ; then
    die "Unable to determine correct toolchain from board."
  fi

  if [[ -z "${FLAGS_remote_pid}" ]] ; then
    if [[ -z "${FLAGS_remote_file}" ]] ; then
      if [[ -z "${FLAGS_attach}" ]] ; then
        die "--remote_file is required."
      fi
    fi
  fi

  # Verify that the correct cross-gdb has been built first!

  if [[ ! -f /usr/bin/${CHOST}-gdb ]] ; then
    die "${CHOST}-gdb does not exist. Please run setup_board."
  fi

  # Verify that the IP Address is currently active.

  if [[ -z "${FLAGS_remote}" ]] ; then
    die "No IP address specified."
  fi

  echo "Verifying IP address ${FLAGS_remote} (this will take a few\
 seconds)..."

  if ! ping -c 3 -q ${FLAGS_remote} > /dev/null ; then
    die "${FLAGS_remote} is not currently available."
  fi

  if [[ -n "${FLAGS_attach}" ]]; then
    if [[ "${FLAGS_attach}" == "browser" ]]; then
      FLAGS_remote_pid=$(run_remote_command \
        "pstree -p|grep session_manager|cut -d\( -f3 | cut -d\) -f1")
      if [ -z "${FLAGS_remote_pid}" ]; then
        die "Unable to find browser process"
      fi
    else
      FLAGS_remote_pid=$(run_remote_command "pgrep -f '${FLAGS_attach}'")
      local count=$(echo ${FLAGS_remote_pid} | wc -w)
      if [ ${count} -eq 0 ]; then
        die "No process matching ${FLAGS_attach}"
      elif [ ${count} -gt 1 ]; then
        error "Multiple (${count}) processes matching \"${FLAGS_attach}\":"
        local pids=$(echo "${FLAGS_remote_pid}" | tr '\n' ' ')
        run_remote_command "ps ${pids}"
        exit 1
      fi
    fi
  fi

  if [[ ${FLAGS_remote_pid} -ne 0 ]] ; then
    local ssh_cmd="readlink -e /proc/${FLAGS_remote_pid}/exe"
    local err_msg="${FLAGS_remote_pid} is not a valid PID on\
 ${FLAGS_remote}"
    FLAGS_remote_file=$(run_remote_command "${ssh_cmd}")
    if [[ $? -ne 0 ]] ; then
      die "${err_msg}"
    fi
  fi

  if [[ ! -z "${FLAGS_remote_file}" ]] ; then
    if [[ ${FLAGS_remote_file:0:1} != '/' ]] ; then
      die "--remote_file must contain full pathname."
    fi
  fi

  # Verify that the debug version of the remote file exists.

  if [ ! -x "${BOARD_ROOT}${FLAGS_remote_file}" ]; then
    echo
    warn "${BOARD_ROOT}${FLAGS_remote_file} does not exist on your local"
    warn "machine or is not executable.  You may need to re-run build_packages"
    warn "before attempting to debug."
    echo
    read -p "Do you want to stop now? [y/n] " y_or_n
    case "$y_or_n" in
      y | Y ) exit 1 ;;
      *) ;;
    esac
  fi
}

setup_remote_iptable ()
{
  # Update the iptables on the remote device

  local ssh_cmd="/sbin/iptables -A INPUT -p tcp --dport ${FLAGS_port}\
 -j ACCEPT"
  local err_msg="Unable to add port to iptables."
  ssh_to_remote_machine "${ssh_cmd}" "${err_msg}"
}

start_remote_gdbserver ()
{
  # Start gdbserver on the remote device

  local gdbserver_cmd="gdbserver :${FLAGS_port} ${FLAGS_remote_file}"
  if [[ ${FLAGS_remote_pid} -ne 0 ]] ; then
    gdbserver_cmd="gdbserver --attach :${FLAGS_port} ${FLAGS_remote_pid}"
  fi

  echo "Starting up gdbserver on your remote device."
  local ssh_cmd="nohup ${gdbserver_cmd} > /tmp/gdbserver.out 2>&1 &"
  local err_msg="Unable to ssh into root@${FLAGS_remote}."
  ssh_to_remote_machine "${ssh_cmd}" "${err_msg}"
}

generate_gdbinit_file ()
{
  # Create board-and-notebook-specific .gdbinit file.

  cat <<-EOF > ${GDBINIT_FILE}

define remote_connect
  set \$file="${FLAGS_remote_file}"
  python import os
  python filename = str (gdb.parse_and_eval ("\$file"))
  python fullname = os.path.join ("${BOARD_ROOT}", filename)
  python file_command = "file " + fullname
  python gdb.execute (file_command)
  python remote_ip_address = "${FLAGS_remote}"
  python remote_port = "${FLAGS_port}"
  python remote_cmd = "target remote " + remote_ip_address + ":" + remote_port
  python gdb.execute (remote_cmd)
end

set sysroot $BOARD_ROOT
set debug-file-directory $BOARD_ROOT/usr/lib/debug
remote_connect
EOF
}


# Some special set up is required for accessing the VM on a local machine...

VM_PORT=""
PORT_FORWARDING=""

if [[ "${FLAGS_remote}" == "localhost" ||
      "${FLAGS_remote}" == "127.0.0.1" ]] ; then
  VM_PORT=" -p 9222"
  PORT_FORWARDING=" -L ${FLAGS_port}:localhost:${FLAGS_port}"
else
  setup_remote_iptable
fi

validate_command_options

# If accessing the VM on the local machine, need a second ssh session open,
# for port forwarding, so gdb can find gdbserver...

SSHD_PID=0
if [[ -n "${VM_PORT}" ]] ; then
  # Call ssh directly rather than using 'ssh_to_remote_machine' because
  # too many things about this particular call are different.
  ssh -i ${TMP_DIR}/testing_rsa -N \
    ${REMOTE_SSH_FLAGS} \
    root@${FLAGS_remote} ${VM_PORT} ${PORT_FORWARDING} &
  SSH_PID=$!
fi

start_remote_gdbserver

echo "gdbserver is now running remotely.  Output will be written to "
echo "/tmp/gdbserver.out on your remote device."

generate_gdbinit_file

echo "Some helpful GDB commands:"
echo "directory <path> -- causes path to be searched for source files."
echo "info functions <regexp> -- find function matching given regexp."
echo
echo "Some helpful gdb_remote specific commands:"
echo "remote_connect -- reestablish remote connection."
echo

# Start gdb on local machine.

${CHOST}-gdb

cleanup