#!/usr/bin/python3

# Copyright (c) 2012 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.

"""
  Script to generate a zip file of delta-generator and its dependencies.
"""
import logging.handlers
import optparse
import os
import re
import shutil
import subprocess
import sys
import tempfile

REPO_MANIFESTS_DIR = os.environ['REPO_MANIFESTS_DIR']
SCRIPTS_DIR = os.environ['SCRIPTS_DIR']

# GLOBALS
STATIC_FILES = ['%s/version.txt' % REPO_MANIFESTS_DIR,
                '%s/common.sh' % SCRIPTS_DIR,
                '%s/core_sign_update' % SCRIPTS_DIR,
                ]

DYNAMIC_EXECUTABLES = ['/usr/bin/delta_generator',
                       '/usr/bin/updateservicectl',
                       '/usr/bin/bsdiff',
                       '/usr/bin/bspatch']

LD_LINUX_AMD64 = 'ld-linux-x86-64.so.2'
LD_LINUX_ARM64 = 'ld-linux-aarch64.so.1'

# These files will be ignored when present in the dependancy list.
DENY_LIST = [
    # This library does not exist on disk, but is inserted into the
    # executable's memory space when the executable is loaded by the kernel.
    'linux-vdso.so',
    ]

# These files MUST be present in the dependancy list.
# Update WrapExecutableFiles if this file changes names.
# Each architecture requires different allow list libs.
ALLOW_LIST_AMD64 = [
    LD_LINUX_AMD64,
    ]

ALLOW_LIST_ARM64 = [
    LD_LINUX_ARM64,
    ]

LIB_DIR = 'lib.so'

# We need directories to be copied recursively to a dest within tempdir
RECURSE_DIRS = {'~/trunk/src/scripts/lib/shflags': 'lib/shflags'}

logging_format = '%(asctime)s - %(filename)s - %(levelname)-8s: %(message)s'
date_format = '%Y/%m/%d %H:%M:%S'
logging.basicConfig(level=logging.INFO, format=logging_format,
                    datefmt=date_format)

def CreateTempDir():
  """Creates a tempdir and returns the name of the tempdir."""
  temp_dir = tempfile.mkdtemp(suffix='au', prefix='tmp')
  logging.debug('Using tempdir = %s', temp_dir)
  return temp_dir

class _LibNotFound(Exception):
  pass

def _SplitAndStrip(data):
  """Prunes the ldd output, and return a list of needed library names
    Example of data:
        linux-vdso.so.1 =>  (0x00007ffffc96a000)
        libbz2.so.1 => /lib/libbz2.so.1 (0x00007f3ff8782000)
        libc.so.6 => /lib/libc.so.6 (0x00007f3ff83ff000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f3ff89b3000)
    Args:
      data: list of libraries from ldd output
    Returns:
      list of libraries that we should copy

  """
  return_list = []
  for line in data.split('\n'):
    if 'not found' in line:
      raise _LibNotFound(line)
    line = re.sub('.*not a dynamic executable.*', '', line)
    line = re.sub('.* =>\s+', '', line)
    line = re.sub('\(0x.*\)\s?', '', line)
    line = line.strip()
    if not len(line):
      continue
    logging.debug('MATCHED line = %s', line)
    return_list.append(line)

  return return_list


def DepsToCopy(ldd_files, allow_list):
  """Returns a list of deps for a given dynamic executables list.
    Args:
      ldd_files: List of dynamic files that needs to have the deps evaluated
      allow_list: List of files that we should allow
   Returns:
     List of files that are dependencies
  """
  libs = set()
  for file_name in ldd_files:
    logging.debug('Running ldd on %s', file_name)
    cmd = ['/usr/bin/ldd', file_name]
    stdout_data = ''
    stderr_data = ''

    try:
      proc = subprocess.Popen(cmd, stdout=subprocess.PIPE,
                              stderr=subprocess.PIPE)
      (stdout_data, stderr_data) = proc.communicate(input=None)
    except subprocess.CalledProcessError as e:
      logging.error('Command %s failed', cmd)
      logging.error('error code %s', e.returncode)
      logging.error('ouput %s', e.output)
      raise

    if not stdout_data: continue

    stdout_data = stdout_data.decode('utf8')
    stderr_data = stderr_data.decode('utf8')
    logging.debug('ldd for %s = stdout = %s stderr =%s', file_name,
                  stdout_data, stderr_data)

    try:
      libs |= set(_SplitAndStrip(stdout_data))
    except _LibNotFound as ex:
      logging.error("ldd for %s failed: %s", file_name, ex)
      sys.exit(1)

  result = _ExcludeDenylist(list(libs), DENY_LIST)
  _EnforceAllowList(list(libs), allow_list=allow_list)
  return result


def CopyRequiredFiles(dest_files_root, allow_list):
  """Generates a list of files that are required for au-generator zip file
    Args:
      dest_files_root: location of the directory where we should copy the files
      allow_list: List of files that we should allow
  """
  if not dest_files_root:
    logging.error('Invalid option passed for dest_files_root')
    sys.exit(1)

  all_files = DYNAMIC_EXECUTABLES + STATIC_FILES
  all_files = list(map(os.path.expanduser, all_files))

  for file_name in all_files:
    if not os.path.isfile(file_name):
      logging.error('file = %s does not exist', file_name)
      sys.exit(1)

  logging.debug('Given files that need to be copied = %s' % '' .join(all_files))
  for file_name in all_files:
    logging.debug('Copying file  %s to %s', file_name, dest_files_root)
    try:
      shutil.copy2(file_name, dest_files_root)
    except EnvironmentError:
      logging.exception("Copying '%s' to %s failed", file_name, dest_files_root)
      sys.exit(1)

  libraries = DepsToCopy(ldd_files=DYNAMIC_EXECUTABLES, allow_list=allow_list)
  lib_dir = os.path.join(dest_files_root, LIB_DIR)
  os.mkdir(lib_dir)
  for file_name in libraries:
    logging.debug('Copying file %s to %s', file_name, lib_dir)
    try:
      shutil.copy2(file_name, lib_dir)
    except EnvironmentError:
      logging.exception("Copying '%s' to %s failed", file_name, lib_dir)
      sys.exit(1)

  for source_dir, target_dir in RECURSE_DIRS.items():
    logging.debug('Processing directory %s', source_dir)
    full_path = os.path.expanduser(source_dir)
    if not os.path.isdir(full_path):
      logging.error("Directory given for %s expanded to %s doens't exist.",
                    source_dir, full_path)
      sys.exit(1)
  dest = os.path.join(dest_files_root, target_dir)
  logging.debug('Copying directory %s to %s.', full_path, target_dir)
  try:
    shutil.copytree(full_path, dest)
  except EnvironmentError:
    logging.exception("Copying tree '%s' to %s failed", full_path, dest)
    sys.exit(1)


def WrapExecutableFiles(dest_files_root, ld_linux):
  """Our dynamically linked executalbes have to be invoked use the library
     versions they were linked with inside the chroot (from libc on), as well
     as the dynamic linker they were built with inside the chroot.

     So, this code moves the execs to backup names, and then creates a shell
     script wrapper which invokes them in the proper way.
  """

  for src_exec in DYNAMIC_EXECUTABLES:
    base_exec = os.path.basename(src_exec)
    local_exec = os.path.join(dest_files_root, base_exec)
    local_exec_wrapped = local_exec + ".bin"
    shutil.move(local_exec, local_exec_wrapped)

    fd = os.open(local_exec, os.O_WRONLY | os.O_CREAT, 0o733)
    with os.fdopen(fd, 'w') as script:
      script.write('#!/bin/sh\n')
      script.write('# Auto-generated wrapper script\n')
      script.write('thisdir="$(dirname "$0")"\n')
      script.write('LD_LIBRARY_PATH=\n')
      script.write('exec "$thisdir/%s/%s"'
                   ' --library-path "$thisdir/%s"'
                   ' "$thisdir/%s.bin" "$@"\n' %
                   (LIB_DIR, ld_linux, LIB_DIR, base_exec))


def CleanUp(temp_dir):
  """Cleans up the tempdir
    Args:
      temp_dir = name of the directory to cleanup
  """
  if os.path.exists(temp_dir):
    shutil.rmtree(temp_dir, ignore_errors=True)
    logging.debug('Removed tempdir = %s', temp_dir)


def GenerateZipFile(base_name, root_dir):
  """Returns true if able to generate zip file
    Args:
      base_name: name of the zip file
      root_dir: location of the directory that we should zip
    Returns:
      True if successfully generates the zip file otherwise False
  """
  logging.debug('Generating zip file %s with contents from %s', base_name,
               root_dir)
  current_dir = os.getcwd()
  os.chdir(root_dir)
  try:
    subprocess.Popen(['zip', '-r', '-9', base_name, '.'],
                     stdout=subprocess.PIPE).communicate()[0]
  except OSError as e:
   logging.error('Execution failed:%s', e.strerror)
   return False
  finally:
    os.chdir(current_dir)

  return True


def _ExcludeDenylist(library_list, deny_list=[]):
  """Deletes the set of files from deny_list from the library_list
    Args:
      library_list: List of the library names to filter through deny_list
      deny_list: List of the deny listed names to filter
    Returns:
      Filtered library_list
  """

  if not deny_list:
    return library_list

  return_list = []
  pattern = re.compile(r'|'.join(deny_list))

  logging.debug('PATTERN: %s=', pattern)

  for library in library_list:
    if pattern.search(library):
      logging.debug('DENY-LISTED = %s=', library)
      continue
    return_list.append(library)

  logging.debug('Returning return_list=%s=', return_list)

  return return_list


def _EnforceAllowList(library_list, allow_list=[]):
  """Ensures that library_list contains all the items from allow_list
    Args:
      library_list: List of the library names to check
      allow_list: List of the items that ought to be in the library_list
  """

  for allow_item in allow_list:
    pattern = re.compile(allow_item)

    logging.debug('PATTERN: %s=', pattern)

    found = False
    for library in library_list:
      if pattern.search(library):
        found = True
        break

    if not found:
      logging.error('Required ALLOW_LIST items %s not found!!!' % allow_item)
      exit(1)


def CopyZipToFinalDestination(output_dir, zip_file_name):
  """Copies the generated zip file to a final destination
  Args:
    output_dir: Directory where the file should be copied to
    zip_file_name: name of the zip file that should be copied
  Returns:
    True on Success False on Failure
  """
  if not os.path.isfile(zip_file_name):
    logging.error("Zip file %s doesn't exist. Returning False", zip_file_name)
    return False

  if not os.path.isdir(output_dir):
    logging.debug('Creating %s', output_dir)
    os.makedirs(output_dir)
  logging.debug('Copying %s to %s', zip_file_name, output_dir)
  shutil.copy2(zip_file_name, output_dir)
  return True


def main():
  """Main function to start the script"""
  parser = optparse.OptionParser()

  parser.add_option( '-d', '--debug', dest='debug', action='store_true',
                     default=False, help='Verbose Default: False',)
  parser.add_option('-o', '--output-dir', dest='output_dir',
                    default='/tmp/au-generator',
                    help='Specify the output location for copying the zipfile')
  parser.add_option('-z', '--zip-name', dest='zip_name',
                    default='au-generator.zip', help='Name of the zip file')
  parser.add_option('-k', '--keep-temp', dest='keep_temp', default=False,
                    action='store_true', help='Keep the temp files...',)
  parser.add_option('-a', '--arch', dest='arch',
                     default='amd64', help='Arch amd64/arm64. Default: amd64',)

  (options, args) = parser.parse_args()
  if options.debug:
    logging.getLogger().setLevel(logging.DEBUG)

  logging.debug('Options are %s ', options)

  temp_dir = CreateTempDir()
  dest_files_root = os.path.join(temp_dir, 'au-generator')
  os.makedirs(dest_files_root)

  if options.arch == 'arm64':
    ld_linux = LD_LINUX_ARM64
    allow_list = ALLOW_LIST_ARM64
  else:
    ld_linux = LD_LINUX_AMD64
    allow_list = ALLOW_LIST_AMD64

  CopyRequiredFiles(dest_files_root=dest_files_root, allow_list=allow_list)
  WrapExecutableFiles(dest_files_root=dest_files_root, ld_linux=ld_linux)
  zip_file_name = os.path.join(temp_dir, options.zip_name)
  GenerateZipFile(zip_file_name, dest_files_root)
  CopyZipToFinalDestination(options.output_dir, zip_file_name)
  logging.info('Generated %s/%s' % (options.output_dir, options.zip_name))

  if not options.keep_temp:
    CleanUp(temp_dir)

if __name__ == '__main__':
  main()