Add m-esr52 at 52.6.0

1 files changed, 816 insertions, 0 deletions

diff --git a/python/mozbuild/mozpack/mozjar.py b/python/mozbuild/mozpack/mozjar.py
new file mode 100644
index 000000000..a1ada8594
--- /dev/null
+++ b/python/mozbuild/mozpack/mozjar.py
@@ -0,0 +1,816 @@
+# 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/.
+
+from __future__ import absolute_import
+
+from io import BytesIO
+import struct
+import zlib
+import os
+from zipfile import (
+    ZIP_STORED,
+    ZIP_DEFLATED,
+)
+from collections import OrderedDict
+from urlparse import urlparse, ParseResult
+import mozpack.path as mozpath
+
+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(object):
+    '''
+    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,
+        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': ('I', 4), 'uint16': ('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.itervalues()
+                               if not t 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.iteritems():
+            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 not name 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.iteritems():
+            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('<' + format, data)[0], size
+
+    def serialize(self):
+        '''
+        Serialize the data structure according to the data structure definition
+        from self.STRUCT.
+        '''
+        serialized = struct.pack('<I', self.signature)
+        sizes = dict((t, name) for name, t in self.STRUCT.iteritems()
+                     if not t in JarStruct.TYPE_MAPPING)
+        for name, t in self.STRUCT.iteritems():
+            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('<' + format, value)
+            else:
+                serialized += 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.iteritems():
+            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 not key 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 self._values.iteritems()
+
+    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(object):
+    '''
+    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 ['filename', 'compressed_size',
+                     'uncompressed_size', 'crc32']:
+            setattr(self, name, header[name])
+        self.compressed = header['compression'] == JAR_DEFLATED
+
+    def read(self, length=-1):
+        '''
+        Read some amount of uncompressed data.
+        '''
+        return self.uncompressed_data.read(length)
+
+    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 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.compressed:
+            data = zlib.decompress(data.tobytes(), -MAX_WBITS)
+        else:
+            data = data.tobytes()
+        if len(data) != self.uncompressed_size:
+            raise JarReaderError('Corrupted file? %s' % self.filename)
+        self._uncompressed_data = BytesIO(data)
+        return self._uncompressed_data
+
+
+class JarReader(object):
+    '''
+    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 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 xrange(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 & (040000 << 16)):
+                continue
+            entries[entry['filename']] = entry
+            if entry['offset'] < preload:
+                self._last_preloaded = entry['filename']
+        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.itervalues():
+            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(object):
+    '''
+    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, optimize=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')
+        self._compress = compress
+        self._compress_level = compress_level
+        self._contents = OrderedDict()
+        self._last_preloaded = None
+        self._optimize = optimize
+
+    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.itervalues():
+            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'] == 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'] = 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 self._optimize:
+            end['cdir_offset'] = 4
+            offset = end['cdir_size'] + end['cdir_offset'] + end.size
+            if preload_size:
+                preload_size += offset
+            self._data.write(struct.pack('<I', preload_size))
+            for entry, _ in self._contents.itervalues():
+                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.itervalues():
+            self._data.write(headers[entry].serialize())
+            self._data.write(content)
+        # On non optimized archives, store the central directory entries.
+        if not self._optimize:
+            end['cdir_offset'] = offset
+            for entry, _ in self._contents.itervalues():
+                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 if the given data should be compressed
+        (True), not compressed (False), or compressed according to the default
+        defined when creating the JarWriter (None).
+        When the data should be compressed (True or None with self.compress ==
+        True), 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.
+        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.
+        '''
+        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 (isinstance(data, JarFileReader) and data.compressed == compress) \
+                or (isinstance(data, Deflater) and data.compress == compress):
+            deflater = data
+        else:
+            deflater = Deflater(compress, compress_level=self._compress_level)
+            if isinstance(data, basestring):
+                deflater.write(data)
+            elif hasattr(data, 'read'):
+                if hasattr(data, 'seek'):
+                    data.seek(0)
+                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 not None:
+            # 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) << 16L
+        if deflater.compressed:
+            entry['min_version'] = 20  # Version 2.0 supports deflated streams
+            entry['general_flag'] = 2  # Max compression
+            entry['compression'] = JAR_DEFLATED
+        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
+        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 not f in self._contents:
+                continue
+            new_contents[f] = self._contents[f]
+            self._last_preloaded = f
+        for f in self._contents:
+            if not f in new_contents:
+                new_contents[f] = self._contents[f]
+        self._contents = new_contents
+
+
+class Deflater(object):
+    '''
+    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 whether to
+        try to compress at all.
+        '''
+        self._data = BytesIO()
+        self.compress = compress
+        if compress:
+            self._deflater = zlib.compressobj(compress_level, zlib.DEFLATED,
+                                              -MAX_WBITS)
+            self._deflated = BytesIO()
+        else:
+            self._deflater = None
+
+    def write(self, data):
+        '''
+        Append a buffer to the Deflater.
+        '''
+        self._data.write(data)
+        if self.compress:
+            if self._deflater:
+                if isinstance(data, memoryview):
+                    data = data.tobytes()
+                self._deflated.write(self._deflater.compress(data))
+            else:
+                raise JarWriterError("Can't write after flush")
+
+    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 crc32(self):
+        '''
+        Return the crc32 of the data written to the Deflater.
+        '''
+        return zlib.crc32(self._data.getvalue()) & 0xffffffff
+
+    @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 (see
+    canonicalize for more details on the key value), 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, 'r')
+        urlmap = {}
+        for line in fileobj:
+            url, path = line.strip().split(None, 1)
+            if not url or not path:
+                continue
+            if url not in urlmap:
+                urlmap[url] = JarLog.canonicalize(url)
+            jar = urlmap[url]
+            entry = self.setdefault(jar, [])
+            if path not in entry:
+                entry.append(path)
+
+    @staticmethod
+    def canonicalize(url):
+        '''
+        The jar path is stored in a MOZ_JAR_LOG_FILE log as a url. This method
+        returns a unique value corresponding to such urls.
+        - file:///{path} becomes {path}
+        - jar:file:///{path}!/{subpath} becomes ({path}, {subpath})
+        - jar:jar:file:///{path}!/{subpath}!/{subpath2} becomes
+           ({path}, {subpath}, {subpath2})
+        '''
+        if not isinstance(url, ParseResult):
+            # Assume that if it doesn't start with jar: or file:, it's a path.
+            if not url.startswith(('jar:', 'file:')):
+                url = 'file:///' + os.path.abspath(url)
+            url = urlparse(url)
+        assert url.scheme
+        assert url.scheme in ('jar', 'file')
+        if url.scheme == 'jar':
+            path = JarLog.canonicalize(url.path)
+            if isinstance(path, tuple):
+                return path[:-1] + tuple(path[-1].split('!/', 1))
+            return tuple(path.split('!/', 1))
+        if url.scheme == 'file':
+            assert os.path.isabs(url.path)
+            path = url.path
+            # On Windows, url.path will be /drive:/path ; on Unix systems,
+            # /path. As we want drive:/path instead of /drive:/path on Windows,
+            # remove the leading /.
+            if os.path.isabs(path[1:]):
+                path = path[1:]
+            path = os.path.realpath(path)
+            return mozpath.normsep(os.path.normcase(path))