build_tar.py

# Copyright 2015 The Bazel Authors. All rights reserved.
#
# 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.
"""This tool build tar files from a list of inputs."""

import argparse
import os
import tarfile
import tempfile

from pkg.private import archive
from pkg.private import helpers
from pkg.private import build_info
from pkg.private import manifest
from pkg.private.tar import tar_writer


def normpath(path):
  r"""Normalize a path to the format we need it.

  os.path.normpath changes / to \ on windows, but tarfile needs / style paths.

  Args:
    path: (str) path to normalize.
  """
  return os.path.normpath(path).replace(os.path.sep, '/')


class TarFile(object):
  """A class to generates a TAR file."""

  class DebError(Exception):
    pass

  def __init__(self, output, directory, compression, compressor, create_parents,
               allow_dups_from_deps, default_mtime, compression_level):
    # Directory prefix on all output paths
    d = directory.strip('/')
    self.directory = (d + '/') if d else None
    self.output = output
    self.compression = compression
    self.compressor = compressor
    self.default_mtime = default_mtime
    self.create_parents = create_parents
    self.allow_dups_from_deps = allow_dups_from_deps
    self.compression_level = compression_level

  def __enter__(self):
    self.tarfile = tar_writer.TarFileWriter(
        self.output,
        self.compression,
        self.compressor,
        self.create_parents,
        self.allow_dups_from_deps,
        default_mtime=self.default_mtime,
        compression_level=self.compression_level)
    return self

  def __exit__(self, t, v, traceback):
    self.tarfile.close()

  def normalize_path(self, path: str) -> str:
    dest = normpath(path)
    # paths should not have a leading ./
    if dest.startswith('./'):
      dest = dest[2:]
    # No path should ever come in with slashs on either end, but protect
    # against that anyway.
    dest = dest.strip('/')
    # This prevents a potential problem for users with both a prefix_dir and
    # symlinks that also repeat the prefix_dir. The old behavior was that we
    # would get just the symlink path. Now we are prefixing with the prefix,
    # so you get the file in the wrong place.
    # We silently de-dup that. If people come up with a real use case for
    # the /a/b/a/b/rest... output we can start an issue and come up with a
    # solution at that time.
    if self.directory and not dest.startswith(self.directory):
      dest = self.directory + dest
    return dest

  def add_file(self, f, destfile, mode=None, ids=None, names=None):
    """Add a file to the tar file.

    Args:
       f: the file to add to the layer
       destfile: the name of the file in the layer
       mode: (int) force to set the specified mode, by default the value from the
         source is taken.
       ids: (uid, gid) for the file to set ownership
       names: (username, groupname) for the file to set ownership. `f` will be
         copied to `self.directory/destfile` in the layer.
    """
    dest = self.normalize_path(destfile)
    # If mode is unspecified, derive the mode from the file's mode.
    if mode is None:
      mode = 0o755 if os.access(f, os.X_OK) else 0o644
    if ids is None:
      ids = (0, 0)
    if names is None:
      names = ('', '')
    self.tarfile.add_file(
        dest,
        file_content=f,
        mode=mode,
        uid=ids[0],
        gid=ids[1],
        uname=names[0],
        gname=names[1])

  def add_empty_file(self,
                     destfile,
                     mode=None,
                     ids=None,
                     names=None,
                     kind=tarfile.REGTYPE):
    """Add a file to the tar file.

    Args:
       destfile: the name of the file in the layer
       mode: force to set the specified mode, defaults to 644
       ids: (uid, gid) for the file to set ownership
       names: (username, groupname) for the file to set ownership.
       kind: type of the file. tarfile.DIRTYPE for directory.  An empty file
         will be created as `destfile` in the layer.
    """
    dest = destfile.lstrip('/')  # Remove leading slashes
    # If mode is unspecified, assume read only
    if mode is None:
      mode = 0o644
    if ids is None:
      ids = (0, 0)
    if names is None:
      names = ('', '')
    dest = normpath(dest)
    self.tarfile.add_file(
        dest,
        content='' if kind == tarfile.REGTYPE else None,
        kind=kind,
        mode=mode,
        uid=ids[0],
        gid=ids[1],
        uname=names[0],
        gname=names[1])

  def add_empty_dir(self, destpath, mode=None, ids=None, names=None):
    """Add a directory to the tar file.

    Args:
       destpath: the name of the directory in the layer
       mode: force to set the specified mode, defaults to 644
       ids: (uid, gid) for the file to set ownership
       names: (username, groupname) for the file to set ownership.  An empty
         file will be created as `destfile` in the layer.
    """
    self.add_empty_file(
        destpath, mode=mode, ids=ids, names=names, kind=tarfile.DIRTYPE)

  def add_tar(self, tar):
    """Merge a tar file into the destination tar file.

    All files presents in that tar will be added to the output file
    under self.directory/path. No user name nor group name will be
    added to the output.

    Args:
      tar: the tar file to add
    """
    self.tarfile.add_tar(tar, numeric=True, prefix=self.directory)

  def add_link(self, symlink, destination, mode=None, ids=None, names=None):
    """Add a symbolic link pointing to `destination`.

    Args:
      symlink: the name of the symbolic link to add.
      destination: where the symbolic link point to.
      mode: (int) force to set the specified posix mode (e.g. 0o755). The
        default is derived from the source
      ids: (uid, gid) for the file to set ownership
      names: (username, groupname) for the file to set ownership.  An empty
        file will be created as `destfile` in the layer.
    """
    if not symlink.startswith("./"):
      dest = self.normalize_path(symlink)
    else:
      dest = symlink
    self.tarfile.add_file(
        dest,
        tarfile.SYMTYPE,
        link=destination,
        mode = mode,
        uid=ids[0],
        gid=ids[1],
        uname=names[0],
        gname=names[1])

  def add_deb(self, deb):
    """Extract a debian package in the output tar.

    All files presents in that debian package will be added to the
    output tar under the same paths. No user name nor group names will
    be added to the output.

    Args:
      deb: the tar file to add

    Raises:
      DebError: if the format of the deb archive is incorrect.
    """
    with archive.SimpleArReader(deb) as arfile:
      current = next(arfile)
      while current and not current.filename.startswith('data.'):
        current = next(arfile)
      if not current:
        raise self.DebError(deb + ' does not contains a data file!')
      tmpfile = tempfile.mkstemp(suffix=os.path.splitext(current.filename)[-1])
      with open(tmpfile[1], 'wb') as f:
        f.write(current.data)
      self.add_tar(tmpfile[1])
      os.remove(tmpfile[1])

  def add_tree(self, tree_top, destpath, mode=None, ids=None, names=None):
    """Add a tree artifact to the tar file.

    Args:
       tree_top: the top of the tree to add
       destpath: the path under which to place the files
       mode: (int) force to set the specified posix mode (e.g. 0o755). The
         default is derived from the source
       ids: (uid, gid) for the file to set ownership
       names: (username, groupname) for the file to set ownership. `f` will be
         copied to `self.directory/destfile` in the layer.
    """
    # We expect /-style paths.
    tree_top = normpath(tree_top)

    dest = destpath.strip('/')  # redundant, dests should never have / here
    if self.directory and self.directory != '/':
      dest = self.directory.lstrip('/') + '/' + dest

    # Again, we expect /-style paths.
    dest = normpath(dest)
    # normpath may be ".", and dest paths should not start with "./"
    dest = '' if dest == '.' else dest + '/'

    if ids is None:
      ids = (0, 0)
    if names is None:
      names = ('', '')

    to_write = {}
    for root, dirs, files in os.walk(tree_top):
      # While `tree_top` uses '/' as a path separator, results returned by
      # `os.walk` and `os.path.join` on Windows may not.
      root = normpath(root)

      dirs = sorted(dirs)
      rel_path_from_top = root[len(tree_top):].lstrip('/')
      if rel_path_from_top:
        dest_dir = dest + rel_path_from_top + '/'
      else:
        dest_dir = dest
      for dir in dirs:
        to_write[dest_dir + dir] = None
      for file in sorted(files):
        content_path = os.path.abspath(os.path.join(root, file))
        if os.name == "nt":
          # "To specify an extended-length path, use the `\\?\` prefix. For
          # example, `\\?\D:\very long path`."[1]
          #
          # [1]: https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation
          to_write[dest_dir + file] = "\\\\?\\" + content_path
        else:
          to_write[dest_dir + file] = content_path

    for path in sorted(to_write.keys()):
      content_path = to_write[path]
      if not content_path:
        # This is an intermediate directory. Bazel has no API to specify modes
        # for this, so the least surprising thing we can do is make it the
        # canonical rwxr-xr-x
        self.add_empty_file(
            path,
            mode=0o755,
            ids=ids,
            names=names,
            kind=tarfile.DIRTYPE)
      else:
        # If mode is unspecified, derive the mode from the file's mode.
        if mode is None:
          f_mode = 0o755 if os.access(content_path, os.X_OK) else 0o644
        else:
          f_mode = mode
        self.tarfile.add_file(
            path,
            file_content=content_path,
            mode=f_mode,
            uid=ids[0],
            gid=ids[1],
            uname=names[0],
            gname=names[1])

  def add_manifest_entry(self, entry, file_attributes):
    # Use the pkg_tar mode/owner remapping as a fallback
    non_abs_path = entry.dest.strip('/')
    if file_attributes:
      attrs = file_attributes(non_abs_path)
    else:
      attrs = {}
    # But any attributes from the manifest have higher precedence
    if entry.mode is not None and entry.mode != '':
      attrs['mode'] = int(entry.mode, 8)
    if entry.user:
      if entry.group:
        attrs['names'] = (entry.user, entry.group)
      else:
        # Use group that legacy tar process would assign
        attrs['names'] = (entry.user, attrs.get('names')[1])
    if entry.uid is not None:
      if entry.gid is not None:
        attrs['ids'] = (entry.uid, entry.gid)
      else:
        attrs['ids'] = (entry.uid, entry.uid)
    if entry.type == manifest.ENTRY_IS_LINK:
      self.add_link(entry.dest, entry.src, **attrs)
    elif entry.type == manifest.ENTRY_IS_DIR:
      self.add_empty_dir(self.normalize_path(entry.dest), **attrs)
    elif entry.type == manifest.ENTRY_IS_TREE:
      self.add_tree(entry.src, entry.dest, **attrs)
    elif entry.type == manifest.ENTRY_IS_EMPTY_FILE:
      self.add_empty_file(self.normalize_path(entry.dest), **attrs)
    else:
      self.add_file(entry.src, entry.dest, **attrs)


def main():
  parser = argparse.ArgumentParser(
      description='Helper for building tar packages',
      fromfile_prefix_chars='@')
  parser.add_argument('--output', required=True,
                      help='The output file, mandatory.')
  parser.add_argument('--manifest',
                      help='manifest of contents to add to the layer.')
  parser.add_argument('--mode',
                      help='Force the mode on the added files (in octal).')
  parser.add_argument(
      '--mtime',
      help='Set mtime on tar file entries. May be an integer or the'
           ' value "portable", to get the value 2000-01-01, which is'
           ' is usable with non *nix OSes.')
  parser.add_argument('--tar', action='append',
                      help='A tar file to add to the layer')
  parser.add_argument('--deb', action='append',
                      help='A debian package to add to the layer')
  parser.add_argument(
      '--directory',
      help='Directory in which to store the file inside the layer')

  compression = parser.add_mutually_exclusive_group()
  compression.add_argument('--compression',
                           help='Compression (`gz` or `bz2`), default is none.')
  compression.add_argument('--compressor',
                           help='Compressor program and arguments, '
                                'e.g. `pigz -p 4`')

  parser.add_argument(
      '--modes', action='append',
      help='Specific mode to apply to specific file (from the file argument),'
           ' e.g., path/to/file=0455.')
  parser.add_argument(
      '--owners', action='append',
      help='Specify the numeric owners of individual files, '
           'e.g. path/to/file=0.0.')
  parser.add_argument(
      '--owner', default='0.0',
      help='Specify the numeric default owner of all files,'
           ' e.g., 0.0')
  parser.add_argument(
      '--owner_name',
      help='Specify the owner name of all files, e.g. root.root.')
  parser.add_argument(
      '--owner_names', action='append',
      help='Specify the owner names of individual files, e.g. '
           'path/to/file=root.root.')
  parser.add_argument('--stamp_from', default='',
                      help='File to find BUILD_STAMP in')
  parser.add_argument('--create_parents',
                      action='store_true',
                      help='Automatically creates parent directories implied by a'
                           ' prefix if they do not exist')
  parser.add_argument('--allow_dups_from_deps',
                      action='store_true',
                      help='')
  parser.add_argument(
      '--compression_level', default=-1,
      help='Specify the numeric compress level in gzip mode; may be 0-9 or -1 (default to 6).')
  options = parser.parse_args()

  # Parse modes arguments
  default_mode = None
  if options.mode:
    # Convert from octal
    default_mode = int(options.mode, 8)

  mode_map = {}
  if options.modes:
    for filemode in options.modes:
      (f, mode) = helpers.SplitNameValuePairAtSeparator(filemode, '=')
      if f[0] == '/':
        f = f[1:]
      mode_map[f] = int(mode, 8)

  default_ownername = ('', '')
  if options.owner_name:
    default_ownername = options.owner_name.split('.', 1)
  names_map = {}
  if options.owner_names:
    for file_owner in options.owner_names:
      (f, owner) = helpers.SplitNameValuePairAtSeparator(file_owner, '=')
      (user, group) = owner.split('.', 1)
      if f[0] == '/':
        f = f[1:]
      names_map[f] = (user, group)

  default_ids = options.owner.split('.', 1)
  default_ids = (int(default_ids[0]), int(default_ids[1]))
  ids_map = {}
  if options.owners:
    for file_owner in options.owners:
      (f, owner) = helpers.SplitNameValuePairAtSeparator(file_owner, '=')
      (user, group) = owner.split('.', 1)
      if f[0] == '/':
        f = f[1:]
      ids_map[f] = (int(user), int(group))

  default_mtime = options.mtime
  if options.stamp_from:
    default_mtime = build_info.get_timestamp(options.stamp_from)

  compression_level = -1
  if options.compression_level:
    compression_level = int(options.compression_level)

  # Add objects to the tar file
  with TarFile(
      options.output,
      directory = helpers.GetFlagValue(options.directory),
      compression = options.compression,
      compressor = options.compressor,
      default_mtime=default_mtime,
      create_parents=options.create_parents,
      allow_dups_from_deps=options.allow_dups_from_deps,
      compression_level = compression_level) as output:

    def file_attributes(filename):
      if filename.startswith('/'):
        filename = filename[1:]
      return {
          'mode': mode_map.get(filename, default_mode),
          'ids': ids_map.get(filename, default_ids),
          'names': names_map.get(filename, default_ownername),
      }

    if options.manifest:
      with open(options.manifest, 'r') as manifest_fp:
        manifest_entries = manifest.read_entries_from(manifest_fp)
        for entry in manifest_entries:
          output.add_manifest_entry(entry, file_attributes)

    for tar in options.tar or []:
      output.add_tar(tar)
    for deb in options.deb or []:
      output.add_deb(deb)


if __name__ == '__main__':
  main()