tor-browser

mozjar.py (29180B)

---

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

import functools
import os
import struct
import zlib
from collections import OrderedDict
from io import BytesIO, UnsupportedOperation
from zipfile import ZIP_DEFLATED, ZIP_STORED

import mozpack.path as mozpath
from mozbuild.util import ensure_bytes

JAR_STORED = ZIP_STORED
JAR_DEFLATED = ZIP_DEFLATED
MAX_WBITS = 15


class JarReaderError(Exception):
   """Error type for Jar reader errors."""


class JarWriterError(Exception):
   """Error type for Jar writer errors."""


class JarStruct:
   """
   Helper used to define ZIP archive raw data structures. Data structures
   handled by this helper all start with a magic number, defined in
   subclasses MAGIC field as a 32-bits unsigned integer, followed by data
   structured as described in subclasses STRUCT field.

   The STRUCT field contains a list of (name, type) pairs where name is a
   field name, and the type can be one of 'uint32', 'uint16' or one of the
   field names. In the latter case, the field is considered to be a string
   buffer with a length given in that field.
   For example,

   .. code-block:: python

       STRUCT = [
           ('version', 'uint32'),
           ('filename_size', 'uint16'),
           ('filename', 'filename_size')
       ]

   describes a structure with a 'version' 32-bits unsigned integer field,
   followed by a 'filename_size' 16-bits unsigned integer field, followed by a
   filename_size-long string buffer 'filename'.

   Fields that are used as other fields size are not stored in objects. In the
   above example, an instance of such subclass would only have two attributes:
     - obj['version']
     - obj['filename']

   filename_size would be obtained with len(obj['filename']).

   JarStruct subclasses instances can be either initialized from existing data
   (deserialized), or with empty fields.
   """

   TYPE_MAPPING = {"uint32": (b"I", 4), "uint16": (b"H", 2)}

   def __init__(self, data=None):
       """
       Create an instance from the given data. Data may be omitted to create
       an instance with empty fields.
       """
       assert self.MAGIC and isinstance(self.STRUCT, OrderedDict)
       self.size_fields = set(
           t for t in self.STRUCT.values() if t not in JarStruct.TYPE_MAPPING
       )
       self._values = {}
       if data:
           self._init_data(data)
       else:
           self._init_empty()

   def _init_data(self, data):
       """
       Initialize an instance from data, following the data structure
       described in self.STRUCT. The self.MAGIC signature is expected at
       data[:4].
       """
       assert data is not None
       self.signature, size = JarStruct.get_data("uint32", data)
       if self.signature != self.MAGIC:
           raise JarReaderError("Bad magic")
       offset = size
       # For all fields used as other fields sizes, keep track of their value
       # separately.
       sizes = dict((t, 0) for t in self.size_fields)
       for name, t in self.STRUCT.items():
           if t in JarStruct.TYPE_MAPPING:
               value, size = JarStruct.get_data(t, data[offset:])
           else:
               size = sizes[t]
               value = data[offset : offset + size]
               if isinstance(value, memoryview):
                   value = value.tobytes()
           if name not in sizes:
               self._values[name] = value
           else:
               sizes[name] = value
           offset += size

   def _init_empty(self):
       """
       Initialize an instance with empty fields.
       """
       self.signature = self.MAGIC
       for name, t in self.STRUCT.items():
           if name in self.size_fields:
               continue
           self._values[name] = 0 if t in JarStruct.TYPE_MAPPING else ""

   @staticmethod
   def get_data(type, data):
       """
       Deserialize a single field of given type (must be one of
       JarStruct.TYPE_MAPPING) at the given offset in the given data.
       """
       assert type in JarStruct.TYPE_MAPPING
       assert data is not None
       format, size = JarStruct.TYPE_MAPPING[type]
       data = data[:size]
       if isinstance(data, memoryview):
           data = data.tobytes()
       return struct.unpack(b"<" + format, data)[0], size

   def serialize(self):
       """
       Serialize the data structure according to the data structure definition
       from self.STRUCT.
       """
       serialized = struct.pack(b"<I", self.signature)
       sizes = dict(
           (t, name)
           for name, t in self.STRUCT.items()
           if t not in JarStruct.TYPE_MAPPING
       )
       for name, t in self.STRUCT.items():
           if t in JarStruct.TYPE_MAPPING:
               format, size = JarStruct.TYPE_MAPPING[t]
               if name in sizes:
                   value = len(self[sizes[name]])
               else:
                   value = self[name]
               serialized += struct.pack(b"<" + format, value)
           else:
               serialized += ensure_bytes(self[name])
       return serialized

   @property
   def size(self):
       """
       Return the size of the data structure, given the current values of all
       variable length fields.
       """
       size = JarStruct.TYPE_MAPPING["uint32"][1]
       for name, type in self.STRUCT.items():
           if type in JarStruct.TYPE_MAPPING:
               size += JarStruct.TYPE_MAPPING[type][1]
           else:
               size += len(self[name])
       return size

   def __getitem__(self, key):
       return self._values[key]

   def __setitem__(self, key, value):
       if key not in self.STRUCT:
           raise KeyError(key)
       if key in self.size_fields:
           raise AttributeError("can't set attribute")
       self._values[key] = value

   def __contains__(self, key):
       return key in self._values

   def __iter__(self):
       return iter(self._values.items())

   def __repr__(self):
       return "<%s %s>" % (
           self.__class__.__name__,
           " ".join("%s=%s" % (n, v) for n, v in self),
       )


class JarCdirEnd(JarStruct):
   """
   End of central directory record.
   """

   MAGIC = 0x06054B50
   STRUCT = OrderedDict([
       ("disk_num", "uint16"),
       ("cdir_disk", "uint16"),
       ("disk_entries", "uint16"),
       ("cdir_entries", "uint16"),
       ("cdir_size", "uint32"),
       ("cdir_offset", "uint32"),
       ("comment_size", "uint16"),
       ("comment", "comment_size"),
   ])


CDIR_END_SIZE = JarCdirEnd().size


class JarCdirEntry(JarStruct):
   """
   Central directory file header
   """

   MAGIC = 0x02014B50
   STRUCT = OrderedDict([
       ("creator_version", "uint16"),
       ("min_version", "uint16"),
       ("general_flag", "uint16"),
       ("compression", "uint16"),
       ("lastmod_time", "uint16"),
       ("lastmod_date", "uint16"),
       ("crc32", "uint32"),
       ("compressed_size", "uint32"),
       ("uncompressed_size", "uint32"),
       ("filename_size", "uint16"),
       ("extrafield_size", "uint16"),
       ("filecomment_size", "uint16"),
       ("disknum", "uint16"),
       ("internal_attr", "uint16"),
       ("external_attr", "uint32"),
       ("offset", "uint32"),
       ("filename", "filename_size"),
       ("extrafield", "extrafield_size"),
       ("filecomment", "filecomment_size"),
   ])


class JarLocalFileHeader(JarStruct):
   """
   Local file header
   """

   MAGIC = 0x04034B50
   STRUCT = OrderedDict([
       ("min_version", "uint16"),
       ("general_flag", "uint16"),
       ("compression", "uint16"),
       ("lastmod_time", "uint16"),
       ("lastmod_date", "uint16"),
       ("crc32", "uint32"),
       ("compressed_size", "uint32"),
       ("uncompressed_size", "uint32"),
       ("filename_size", "uint16"),
       ("extra_field_size", "uint16"),
       ("filename", "filename_size"),
       ("extra_field", "extra_field_size"),
   ])


class JarFileReader:
   """
   File-like class for use by JarReader to give access to individual files
   within a Jar archive.
   """

   def __init__(self, header, data):
       """
       Initialize a JarFileReader. header is the local file header
       corresponding to the file in the jar archive, data a buffer containing
       the file data.
       """
       assert header["compression"] in [JAR_DEFLATED, JAR_STORED]
       self._data = data
       # Copy some local file header fields.
       for name in ["compressed_size", "uncompressed_size", "crc32"]:
           setattr(self, name, header[name])
       self.filename = header["filename"].decode()
       self.compressed = header["compression"] != JAR_STORED
       self.compress = header["compression"]

   def readable(self):
       return True

   def read(self, length=-1):
       """
       Read some amount of uncompressed data.
       """
       return self.uncompressed_data.read(length)

   def readinto(self, b):
       """
       Read bytes into a pre-allocated, writable bytes-like object `b` and return
       the number of bytes read.
       """
       return self.uncompressed_data.readinto(b)

   def readlines(self):
       """
       Return a list containing all the lines of data in the uncompressed
       data.
       """
       return self.read().splitlines(True)

   def __iter__(self):
       """
       Iterator, to support the "for line in fileobj" constructs.
       """
       return iter(self.readlines())

   def seek(self, pos, whence=os.SEEK_SET):
       """
       Change the current position in the uncompressed data. Subsequent reads
       will start from there.
       """
       return self.uncompressed_data.seek(pos, whence)

   def close(self):
       """
       Free the uncompressed data buffer.
       """
       self.uncompressed_data.close()

   @property
   def closed(self):
       return self.uncompressed_data.closed

   @property
   def compressed_data(self):
       """
       Return the raw compressed data.
       """
       return self._data[: self.compressed_size]

   @property
   def uncompressed_data(self):
       """
       Return the uncompressed data.
       """
       if hasattr(self, "_uncompressed_data"):
           return self._uncompressed_data
       data = self.compressed_data
       if self.compress == JAR_STORED:
           data = data.tobytes()
       elif self.compress == JAR_DEFLATED:
           data = zlib.decompress(data.tobytes(), -MAX_WBITS)
       else:
           assert False  # Can't be another value per __init__
       if len(data) != self.uncompressed_size:
           raise JarReaderError("Corrupted file? %s" % self.filename)
       self._uncompressed_data = BytesIO(data)
       return self._uncompressed_data


class JarReader:
   """
   Class with methods to read Jar files. Can open standard jar files as well
   as Mozilla jar files (see further details in the JarWriter documentation).
   """

   def __init__(self, file=None, fileobj=None, data=None):
       """
       Opens the given file as a Jar archive. Use the given file-like object
       if one is given instead of opening the given file name.
       """
       if fileobj:
           data = fileobj.read()
       elif file:
           data = open(file, "rb").read()
       self._data = memoryview(data)
       # The End of Central Directory Record has a variable size because of
       # comments it may contain, so scan for it from the end of the file.
       offset = -CDIR_END_SIZE
       while True:
           signature = JarStruct.get_data("uint32", self._data[offset:])[0]
           if signature == JarCdirEnd.MAGIC:
               break
           if offset == -len(self._data):
               raise JarReaderError("Not a jar?")
           offset -= 1
       self._cdir_end = JarCdirEnd(self._data[offset:])

   def close(self):
       """
       Free some resources associated with the Jar.
       """
       del self._data

   @property
   def compression(self):
       entries = self.entries
       if not entries:
           return JAR_STORED
       return max(f["compression"] for f in entries.values())

   @property
   def entries(self):
       """
       Return an ordered dict of central directory entries, indexed by
       filename, in the order they appear in the Jar archive central
       directory. Directory entries are skipped.
       """
       if hasattr(self, "_entries"):
           return self._entries
       preload = 0
       if self.is_optimized:
           preload = JarStruct.get_data("uint32", self._data)[0]
       entries = OrderedDict()
       offset = self._cdir_end["cdir_offset"]
       for e in range(self._cdir_end["cdir_entries"]):
           entry = JarCdirEntry(self._data[offset:])
           offset += entry.size
           # Creator host system. 0 is MSDOS, 3 is Unix
           host = entry["creator_version"] >> 8
           # External attributes values depend on host above. On Unix the
           # higher bits are the stat.st_mode value. On MSDOS, the lower bits
           # are the FAT attributes.
           xattr = entry["external_attr"]
           # Skip directories
           if (host == 0 and xattr & 0x10) or (host == 3 and xattr & (0o040000 << 16)):
               continue
           entries[entry["filename"].decode()] = entry
           if entry["offset"] < preload:
               self._last_preloaded = entry["filename"].decode()
       self._entries = entries
       return entries

   @property
   def is_optimized(self):
       """
       Return whether the jar archive is optimized.
       """
       # In optimized jars, the central directory is at the beginning of the
       # file, after a single 32-bits value, which is the length of data
       # preloaded.
       return self._cdir_end["cdir_offset"] == JarStruct.TYPE_MAPPING["uint32"][1]

   @property
   def last_preloaded(self):
       """
       Return the name of the last file that is set to be preloaded.
       See JarWriter documentation for more details on preloading.
       """
       if hasattr(self, "_last_preloaded"):
           return self._last_preloaded
       self._last_preloaded = None
       self.entries
       return self._last_preloaded

   def _getreader(self, entry):
       """
       Helper to create a JarFileReader corresponding to the given central
       directory entry.
       """
       header = JarLocalFileHeader(self._data[entry["offset"] :])
       for key, value in entry:
           if key in header and header[key] != value:
               raise JarReaderError(
                   "Central directory and file header "
                   + "mismatch. Corrupted archive?"
               )
       return JarFileReader(header, self._data[entry["offset"] + header.size :])

   def __iter__(self):
       """
       Iterate over all files in the Jar archive, in the form of
       JarFileReaders.
           for file in jarReader:
               ...
       """
       for entry in self.entries.values():
           yield self._getreader(entry)

   def __getitem__(self, name):
       """
       Get a JarFileReader for the given file name.
       """
       return self._getreader(self.entries[name])

   def __contains__(self, name):
       """
       Return whether the given file name appears in the Jar archive.
       """
       return name in self.entries


class JarWriter:
   """
   Class with methods to write Jar files. Can write more-or-less standard jar
   archives as well as jar archives optimized for Gecko. See the documentation
   for the close() member function for a description of both layouts.
   """

   def __init__(self, file=None, fileobj=None, compress=True, compress_level=9):
       """
       Initialize a Jar archive in the given file. Use the given file-like
       object if one is given instead of opening the given file name.
       The compress option determines the default behavior for storing data
       in the jar archive. The optimize options determines whether the jar
       archive should be optimized for Gecko or not. ``compress_level``
       defines the zlib compression level. It must be a value between 0 and 9
       and defaults to 9, the highest and slowest level of compression.
       """
       if fileobj:
           self._data = fileobj
       else:
           self._data = open(file, "wb")
       if compress is True:
           compress = JAR_DEFLATED
       self._compress = compress
       self._compress_level = compress_level
       self._contents = OrderedDict()
       self._last_preloaded = None

   def __enter__(self):
       """
       Context manager __enter__ method for JarWriter.
       """
       return self

   def __exit__(self, type, value, tb):
       """
       Context manager __exit__ method for JarWriter.
       """
       self.finish()

   def finish(self):
       """
       Flush and close the Jar archive.

       Standard jar archives are laid out like the following:
           - Local file header 1
           - File data 1
           - Local file header 2
           - File data 2
           - (...)
           - Central directory entry pointing at Local file header 1
           - Central directory entry pointing at Local file header 2
           - (...)
           - End of central directory, pointing at first central directory
             entry.

       Jar archives optimized for Gecko are laid out like the following:
           - 32-bits unsigned integer giving the amount of data to preload.
           - Central directory entry pointing at Local file header 1
           - Central directory entry pointing at Local file header 2
           - (...)
           - End of central directory, pointing at first central directory
             entry.
           - Local file header 1
           - File data 1
           - Local file header 2
           - File data 2
           - (...)
           - End of central directory, pointing at first central directory
             entry.

       The duplication of the End of central directory is to accomodate some
       Zip reading tools that want an end of central directory structure to
       follow the central directory entries.
       """
       offset = 0
       headers = {}
       preload_size = 0
       # Prepare central directory entries
       for entry, content in self._contents.values():
           header = JarLocalFileHeader()
           for name in entry.STRUCT:
               if name in header:
                   header[name] = entry[name]
           entry["offset"] = offset
           offset += len(content) + header.size
           if entry["filename"].decode() == self._last_preloaded:
               preload_size = offset
           headers[entry] = header
       # Prepare end of central directory
       end = JarCdirEnd()
       end["disk_entries"] = len(self._contents)
       end["cdir_entries"] = end["disk_entries"]
       end["cdir_size"] = functools.reduce(
           lambda x, y: x + y[0].size, self._contents.values(), 0
       )
       # On optimized archives, store the preloaded size and the central
       # directory entries, followed by the first end of central directory.
       if preload_size:
           end["cdir_offset"] = 4
           offset = end["cdir_size"] + end["cdir_offset"] + end.size
           preload_size += offset
           self._data.write(struct.pack("<I", preload_size))
           for entry, _ in self._contents.values():
               entry["offset"] += offset
               self._data.write(entry.serialize())
           self._data.write(end.serialize())
       # Store local file entries followed by compressed data
       for entry, content in self._contents.values():
           self._data.write(headers[entry].serialize())
           if isinstance(content, memoryview):
               self._data.write(content.tobytes())
           else:
               self._data.write(content)
       # On non optimized archives, store the central directory entries.
       if not preload_size:
           end["cdir_offset"] = offset
           for entry, _ in self._contents.values():
               self._data.write(entry.serialize())
       # Store the end of central directory.
       self._data.write(end.serialize())
       self._data.close()

   def add(self, name, data, compress=None, mode=None, skip_duplicates=False):
       """
       Add a new member to the jar archive, with the given name and the given
       data.
       The compress option indicates how the given data should be compressed
       (one of JAR_STORED or JAR_DEFLATE), or compressed according
       to the default defined when creating the JarWriter (None). True and
       False are allowed values for backwards compatibility, mapping,
       respectively, to JAR_DEFLATE and JAR_STORED.
       When the data should be compressed, it is only really compressed if
       the compressed size is smaller than the uncompressed size.
       The mode option gives the unix permissions that should be stored for the
       jar entry, which defaults to 0o100644 (regular file, u+rw, g+r, o+r) if
       not specified.
       If a duplicated member is found skip_duplicates will prevent raising
       an exception if set to True.
       The given data may be a buffer, a file-like instance, a Deflater or a
       JarFileReader instance. The latter two allow to avoid uncompressing
       data to recompress it.
       """
       if isinstance(name, bytes):
           name = name.decode()
       name = mozpath.normsep(name)

       if name in self._contents and not skip_duplicates:
           raise JarWriterError("File %s already in JarWriter" % name)
       if compress is None:
           compress = self._compress
       if compress is True:
           compress = JAR_DEFLATED
       if compress is False:
           compress = JAR_STORED
       if isinstance(data, (JarFileReader, Deflater)) and data.compress == compress:
           deflater = data
       else:
           deflater = Deflater(compress, compress_level=self._compress_level)
           if isinstance(data, (bytes, str)):
               deflater.write(data)
           elif hasattr(data, "read"):
               try:
                   data.seek(0)
               except (UnsupportedOperation, AttributeError):
                   pass
               deflater.write(data.read())
           else:
               raise JarWriterError("Don't know how to handle %s" % type(data))
       # Fill a central directory entry for this new member.
       entry = JarCdirEntry()
       entry["creator_version"] = 20
       if mode is None:
           # If no mode is given, default to u+rw, g+r, o+r.
           mode = 0o000644
       if not mode & 0o777000:
           # If no file type is given, default to regular file.
           mode |= 0o100000
       # Set creator host system (upper byte of creator_version) to 3 (Unix) so
       # mode is honored when there is one.
       entry["creator_version"] |= 3 << 8
       entry["external_attr"] = (mode & 0xFFFF) << 16
       if deflater.compressed:
           entry["min_version"] = 20  # Version 2.0 supports deflated streams
           entry["general_flag"] = 2  # Max compression
           entry["compression"] = deflater.compress
       else:
           entry["min_version"] = 10  # Version 1.0 for stored streams
           entry["general_flag"] = 0
           entry["compression"] = JAR_STORED
       # January 1st, 2010. See bug 592369.
       entry["lastmod_date"] = ((2010 - 1980) << 9) | (1 << 5) | 1
       entry["lastmod_time"] = 0
       entry["crc32"] = deflater.crc32
       entry["compressed_size"] = deflater.compressed_size
       entry["uncompressed_size"] = deflater.uncompressed_size
       entry["filename"] = name.encode()
       self._contents[name] = entry, deflater.compressed_data

   def preload(self, files):
       """
       Set which members of the jar archive should be preloaded when opening
       the archive in Gecko. This reorders the members according to the order
       of given list.
       """
       new_contents = OrderedDict()
       for f in files:
           if f not in self._contents:
               continue
           new_contents[f] = self._contents[f]
           self._last_preloaded = f
       for f in self._contents:
           if f not in new_contents:
               new_contents[f] = self._contents[f]
       self._contents = new_contents


class Deflater:
   """
   File-like interface to zlib compression. The data is actually not
   compressed unless the compressed form is smaller than the uncompressed
   data.
   """

   def __init__(self, compress=True, compress_level=9):
       """
       Initialize a Deflater. The compress argument determines how to
       compress.
       """
       self._data = BytesIO()
       if compress is True:
           compress = JAR_DEFLATED
       elif compress is False:
           compress = JAR_STORED
       self.compress = compress
       if compress == JAR_DEFLATED:
           self._deflater = zlib.compressobj(compress_level, zlib.DEFLATED, -MAX_WBITS)
           self._deflated = BytesIO()
       else:
           assert compress == JAR_STORED
           self._deflater = None
       self.crc32 = 0

   def write(self, data):
       """
       Append a buffer to the Deflater.
       """
       if isinstance(data, memoryview):
           data = data.tobytes()
       if isinstance(data, str):
           data = data.encode()
       self._data.write(data)

       if self.compress:
           if self._deflater:
               self._deflated.write(self._deflater.compress(data))
           else:
               raise JarWriterError("Can't write after flush")

       self.crc32 = zlib.crc32(data, self.crc32) & 0xFFFFFFFF

   def close(self):
       """
       Close the Deflater.
       """
       self._data.close()
       if self.compress:
           self._deflated.close()

   def _flush(self):
       """
       Flush the underlying zlib compression object.
       """
       if self.compress and self._deflater:
           self._deflated.write(self._deflater.flush())
           self._deflater = None

   @property
   def compressed(self):
       """
       Return whether the data should be compressed.
       """
       return self._compressed_size < self.uncompressed_size

   @property
   def _compressed_size(self):
       """
       Return the real compressed size of the data written to the Deflater. If
       the Deflater is set not to compress, the uncompressed size is returned.
       Otherwise, the actual compressed size is returned, whether or not it is
       a win over the uncompressed size.
       """
       if self.compress:
           self._flush()
           return self._deflated.tell()
       return self.uncompressed_size

   @property
   def compressed_size(self):
       """
       Return the compressed size of the data written to the Deflater. If the
       Deflater is set not to compress, the uncompressed size is returned.
       Otherwise, if the data should not be compressed (the real compressed
       size is bigger than the uncompressed size), return the uncompressed
       size.
       """
       if self.compressed:
           return self._compressed_size
       return self.uncompressed_size

   @property
   def uncompressed_size(self):
       """
       Return the size of the data written to the Deflater.
       """
       return self._data.tell()

   @property
   def compressed_data(self):
       """
       Return the compressed data, if the data should be compressed (real
       compressed size smaller than the uncompressed size), or the
       uncompressed data otherwise.
       """
       if self.compressed:
           return self._deflated.getvalue()
       return self._data.getvalue()


class JarLog(dict):
   """
   Helper to read the file Gecko generates when setting MOZ_JAR_LOG_FILE.
   The jar log is then available as a dict with the jar path as key, and
   the corresponding access log as a list value. Only the first access to
   a given member of a jar is stored.
   """

   def __init__(self, file=None, fileobj=None):
       if not fileobj:
           fileobj = open(file)
       for line in fileobj:
           jar, path = line.strip().split(None, 1)
           if not jar or not path:
               continue
           entry = self.setdefault(jar, [])
           if path not in entry:
               entry.append(path)