#!/usr/bin/env python
#
# 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 adb
import argparse
import json
import logging
import os
import posixpath
import re
import shutil
import subprocess
import sys
import tempfile
import textwrap

# Shared functions across gdbclient.py and ndk-gdb.py.
import gdbrunner

g_temp_dirs = []

def get_gdbserver_path(root, arch):
    path = "{}/prebuilts/misc/gdbserver/android-{}/gdbserver{}"
    if arch.endswith("64"):
        return path.format(root, arch, "64")
    else:
        return path.format(root, arch, "")


def get_tracer_pid(device, pid):
    if pid is None:
        return 0

    line, _ = device.shell(["grep", "-e", "^TracerPid:", "/proc/{}/status".format(pid)])
    tracer_pid = re.sub('TracerPid:\t(.*)\n', r'\1', line)
    return int(tracer_pid)


def parse_args():
    parser = gdbrunner.ArgumentParser()

    group = parser.add_argument_group(title="attach target")
    group = group.add_mutually_exclusive_group(required=True)
    group.add_argument(
        "-p", dest="target_pid", metavar="PID", type=int,
        help="attach to a process with specified PID")
    group.add_argument(
        "-n", dest="target_name", metavar="NAME",
        help="attach to a process with specified name")
    group.add_argument(
        "-r", dest="run_cmd", metavar="CMD", nargs=argparse.REMAINDER,
        help="run a binary on the device, with args")

    parser.add_argument(
        "--port", nargs="?", default="5039",
        help="override the port used on the host [default: 5039]")
    parser.add_argument(
        "--user", nargs="?", default="root",
        help="user to run commands as on the device [default: root]")
    parser.add_argument(
        "--setup-forwarding", default=None, choices=["gdb", "vscode"],
        help=("Setup the gdbserver and port forwarding. Prints commands or " +
              ".vscode/launch.json configuration needed to connect the debugging " +
              "client to the server."))

    parser.add_argument(
        "--env", nargs=1, action="append", metavar="VAR=VALUE",
        help="set environment variable when running a binary")

    return parser.parse_args()


def verify_device(root, device):
    name = device.get_prop("ro.product.name")
    target_device = os.environ["TARGET_PRODUCT"]
    if target_device != name:
        msg = "TARGET_PRODUCT ({}) does not match attached device ({})"
        sys.exit(msg.format(target_device, name))


def get_remote_pid(device, process_name):
    processes = gdbrunner.get_processes(device)
    if process_name not in processes:
        msg = "failed to find running process {}".format(process_name)
        sys.exit(msg)
    pids = processes[process_name]
    if len(pids) > 1:
        msg = "multiple processes match '{}': {}".format(process_name, pids)
        sys.exit(msg)

    # Fetch the binary using the PID later.
    return pids[0]


def make_temp_dir(prefix):
    global g_temp_dirs
    result = tempfile.mkdtemp(prefix='gdbclient-linker-')
    g_temp_dirs.append(result)
    return result


def ensure_linker(device, sysroot, interp):
    """Ensure that the device's linker exists on the host.

    PT_INTERP is usually /system/bin/linker[64], but on the device, that file is
    a symlink to /apex/com.android.runtime/bin/linker[64]. The symbolized linker
    binary on the host is located in ${sysroot}/apex, not in ${sysroot}/system,
    so add the ${sysroot}/apex path to the solib search path.

    PT_INTERP will be /system/bin/bootstrap/linker[64] for executables using the
    non-APEX/bootstrap linker. No search path modification is needed.

    For a tapas build, only an unbundled app is built, and there is no linker in
    ${sysroot} at all, so copy the linker from the device.

    Returns:
        A directory to add to the soinfo search path or None if no directory
        needs to be added.
    """

    # Static executables have no interpreter.
    if interp is None:
        return None

    # gdb will search for the linker using the PT_INTERP path. First try to find
    # it in the sysroot.
    local_path = os.path.join(sysroot, interp.lstrip("/"))
    if os.path.exists(local_path):
        return None

    # If the linker on the device is a symlink, search for the symlink's target
    # in the sysroot directory.
    interp_real, _ = device.shell(["realpath", interp])
    interp_real = interp_real.strip()
    local_path = os.path.join(sysroot, interp_real.lstrip("/"))
    if os.path.exists(local_path):
        if posixpath.basename(interp) == posixpath.basename(interp_real):
            # Add the interpreter's directory to the search path.
            return os.path.dirname(local_path)
        else:
            # If PT_INTERP is linker_asan[64], but the sysroot file is
            # linker[64], then copy the local file to the name gdb expects.
            result = make_temp_dir('gdbclient-linker-')
            shutil.copy(local_path, os.path.join(result, posixpath.basename(interp)))
            return result

    # Pull the system linker.
    result = make_temp_dir('gdbclient-linker-')
    device.pull(interp, os.path.join(result, posixpath.basename(interp)))
    return result


def handle_switches(args, sysroot):
    """Fetch the targeted binary and determine how to attach gdb.

    Args:
        args: Parsed arguments.
        sysroot: Local sysroot path.

    Returns:
        (binary_file, attach_pid, run_cmd).
        Precisely one of attach_pid or run_cmd will be None.
    """

    device = args.device
    binary_file = None
    pid = None
    run_cmd = None

    args.su_cmd = ["su", args.user] if args.user else []

    if args.target_pid:
        # Fetch the binary using the PID later.
        pid = args.target_pid
    elif args.target_name:
        # Fetch the binary using the PID later.
        pid = get_remote_pid(device, args.target_name)
    elif args.run_cmd:
        if not args.run_cmd[0]:
            sys.exit("empty command passed to -r")
        run_cmd = args.run_cmd
        if not run_cmd[0].startswith("/"):
            try:
                run_cmd[0] = gdbrunner.find_executable_path(device, args.run_cmd[0],
                                                            run_as_cmd=args.su_cmd)
            except RuntimeError:
              sys.exit("Could not find executable '{}' passed to -r, "
                       "please provide an absolute path.".format(args.run_cmd[0]))

        binary_file, local = gdbrunner.find_file(device, run_cmd[0], sysroot,
                                                 run_as_cmd=args.su_cmd)
    if binary_file is None:
        assert pid is not None
        try:
            binary_file, local = gdbrunner.find_binary(device, pid, sysroot,
                                                       run_as_cmd=args.su_cmd)
        except adb.ShellError:
            sys.exit("failed to pull binary for PID {}".format(pid))

    if not local:
        logging.warning("Couldn't find local unstripped executable in {},"
                        " symbols may not be available.".format(sysroot))

    return (binary_file, pid, run_cmd)

def generate_vscode_script(gdbpath, root, sysroot, binary_name, port, dalvik_gdb_script, solib_search_path):
    # TODO It would be nice if we didn't need to copy this or run the
    #      gdbclient.py program manually. Doing this would probably require
    #      writing a vscode extension or modifying an existing one.
    res = {
        "name": "(gdbclient.py) Attach {} (port: {})".format(binary_name.split("/")[-1], port),
        "type": "cppdbg",
        "request": "launch",  # Needed for gdbserver.
        "cwd": root,
        "program": binary_name,
        "MIMode": "gdb",
        "miDebuggerServerAddress": "localhost:{}".format(port),
        "miDebuggerPath": gdbpath,
        "setupCommands": [
            {
                # Required for vscode.
                "description": "Enable pretty-printing for gdb",
                "text": "-enable-pretty-printing",
                "ignoreFailures": True,
            },
            {
                "description": "gdb command: dir",
                "text": "-environment-directory {}".format(root),
                "ignoreFailures": False
            },
            {
                "description": "gdb command: set solib-search-path",
                "text": "-gdb-set solib-search-path {}".format(":".join(solib_search_path)),
                "ignoreFailures": False
            },
            {
                "description": "gdb command: set solib-absolute-prefix",
                "text": "-gdb-set solib-absolute-prefix {}".format(sysroot),
                "ignoreFailures": False
            },
        ]
    }
    if dalvik_gdb_script:
        res["setupCommands"].append({
            "description": "gdb command: source art commands",
            "text": "-interpreter-exec console \"source {}\"".format(dalvik_gdb_script),
            "ignoreFailures": False,
        })
    return json.dumps(res, indent=4)

def generate_gdb_script(root, sysroot, binary_name, port, dalvik_gdb_script, solib_search_path, connect_timeout):
    solib_search_path = ":".join(solib_search_path)

    gdb_commands = ""
    gdb_commands += "file '{}'\n".format(binary_name)
    gdb_commands += "directory '{}'\n".format(root)
    gdb_commands += "set solib-absolute-prefix {}\n".format(sysroot)
    gdb_commands += "set solib-search-path {}\n".format(solib_search_path)
    if dalvik_gdb_script:
        gdb_commands += "source {}\n".format(dalvik_gdb_script)

    # Try to connect for a few seconds, sometimes the device gdbserver takes
    # a little bit to come up, especially on emulators.
    gdb_commands += """
python

def target_remote_with_retry(target, timeout_seconds):
  import time
  end_time = time.time() + timeout_seconds
  while True:
    try:
      gdb.execute("target extended-remote " + target)
      return True
    except gdb.error as e:
      time_left = end_time - time.time()
      if time_left < 0 or time_left > timeout_seconds:
        print("Error: unable to connect to device.")
        print(e)
        return False
      time.sleep(min(0.25, time_left))

target_remote_with_retry(':{}', {})

end
""".format(port, connect_timeout)

    return gdb_commands

def generate_setup_script(gdbpath, sysroot, linker_search_dir, binary_file, is64bit, port, debugger, connect_timeout=5):
    # Generate a setup script.
    # TODO: Detect the zygote and run 'art-on' automatically.
    root = os.environ["ANDROID_BUILD_TOP"]
    symbols_dir = os.path.join(sysroot, "system", "lib64" if is64bit else "lib")
    vendor_dir = os.path.join(sysroot, "vendor", "lib64" if is64bit else "lib")

    solib_search_path = []
    symbols_paths = ["", "hw", "ssl/engines", "drm", "egl", "soundfx"]
    vendor_paths = ["", "hw", "egl"]
    solib_search_path += [os.path.join(symbols_dir, x) for x in symbols_paths]
    solib_search_path += [os.path.join(vendor_dir, x) for x in vendor_paths]
    if linker_search_dir is not None:
        solib_search_path += [linker_search_dir]

    dalvik_gdb_script = os.path.join(root, "development", "scripts", "gdb", "dalvik.gdb")
    if not os.path.exists(dalvik_gdb_script):
        logging.warning(("couldn't find {} - ART debugging options will not " +
                         "be available").format(dalvik_gdb_script))
        dalvik_gdb_script = None

    if debugger == "vscode":
        return generate_vscode_script(
            gdbpath, root, sysroot, binary_file.name, port, dalvik_gdb_script, solib_search_path)
    elif debugger == "gdb":
        return generate_gdb_script(root, sysroot, binary_file.name, port, dalvik_gdb_script, solib_search_path, connect_timeout)
    else:
        raise Exception("Unknown debugger type " + debugger)


def do_main():
    required_env = ["ANDROID_BUILD_TOP",
                    "ANDROID_PRODUCT_OUT", "TARGET_PRODUCT"]
    for env in required_env:
        if env not in os.environ:
            sys.exit(
                "Environment variable '{}' not defined, have you run lunch?".format(env))

    args = parse_args()
    device = args.device

    if device is None:
        sys.exit("ERROR: Failed to find device.")

    root = os.environ["ANDROID_BUILD_TOP"]
    sysroot = os.path.join(os.environ["ANDROID_PRODUCT_OUT"], "symbols")

    # Make sure the environment matches the attached device.
    verify_device(root, device)

    debug_socket = "/data/local/tmp/debug_socket"
    pid = None
    run_cmd = None

    # Fetch binary for -p, -n.
    binary_file, pid, run_cmd = handle_switches(args, sysroot)

    with binary_file:
        if sys.platform.startswith("linux"):
            platform_name = "linux-x86"
        elif sys.platform.startswith("darwin"):
            platform_name = "darwin-x86"
        else:
            sys.exit("Unknown platform: {}".format(sys.platform))

        arch = gdbrunner.get_binary_arch(binary_file)
        is64bit = arch.endswith("64")

        # Make sure we have the linker
        llvm_readobj_path = os.path.join(root, "prebuilts", "clang", "host", platform_name,
                                         "llvm-binutils-stable", "llvm-readobj")
        interp = gdbrunner.get_binary_interp(binary_file.name, llvm_readobj_path)
        linker_search_dir = ensure_linker(device, sysroot, interp)

        tracer_pid = get_tracer_pid(device, pid)
        if tracer_pid == 0:
            cmd_prefix = args.su_cmd
            if args.env:
                cmd_prefix += ['env'] + [v[0] for v in args.env]

            # Start gdbserver.
            gdbserver_local_path = get_gdbserver_path(root, arch)
            gdbserver_remote_path = "/data/local/tmp/{}-gdbserver".format(arch)
            gdbrunner.start_gdbserver(
                device, gdbserver_local_path, gdbserver_remote_path,
                target_pid=pid, run_cmd=run_cmd, debug_socket=debug_socket,
                port=args.port, run_as_cmd=cmd_prefix)
        else:
            print "Connecting to tracing pid {} using local port {}".format(tracer_pid, args.port)
            gdbrunner.forward_gdbserver_port(device, local=args.port,
                                             remote="tcp:{}".format(args.port))

        gdb_path = os.path.join(root, "prebuilts", "gdb", platform_name, "bin",
                                "gdb")
        # Generate a gdb script.
        setup_commands = generate_setup_script(gdbpath=gdb_path,
                                               sysroot=sysroot,
                                               linker_search_dir=linker_search_dir,
                                               binary_file=binary_file,
                                               is64bit=is64bit,
                                               port=args.port,
                                               debugger=args.setup_forwarding or "gdb")

        if not args.setup_forwarding:
            # Print a newline to separate our messages from the GDB session.
            print("")

            # Start gdb.
            gdbrunner.start_gdb(gdb_path, setup_commands)
        else:
            print("")
            print setup_commands
            print("")
            if args.setup_forwarding == "vscode":
                print textwrap.dedent("""
                        Paste the above json into .vscode/launch.json and start the debugger as
                        normal. Press enter in this terminal once debugging is finished to shutdown
                        the gdbserver and close all the ports.""")
            else:
                print textwrap.dedent("""
                        Paste the above gdb commands into the gdb frontend to setup the gdbserver
                        connection. Press enter in this terminal once debugging is finished to
                        shutdown the gdbserver and close all the ports.""")
            print("")
            raw_input("Press enter to shutdown gdbserver")


def main():
    try:
        do_main()
    finally:
        global g_temp_dirs
        for temp_dir in g_temp_dirs:
            shutil.rmtree(temp_dir)


if __name__ == "__main__":
    main()