from io import BytesIO
import struct
from fontTools.misc import sstruct
from fontTools.misc.textTools import bytesjoin, tostr
from collections import OrderedDict
from collections.abc import MutableMapping
class ResourceError(Exception):
pass
class ResourceReader(MutableMapping):
"""Reader for Mac OS resource forks.
Parses a resource fork and returns resources according to their type.
If run on OS X, this will open the resource fork in the filesystem.
Otherwise, it will open the file itself and attempt to read it as
though it were a resource fork.
The returned object can be indexed by type and iterated over,
returning in each case a list of py:class:`Resource` objects
representing all the resources of a certain type.
"""
def __init__(self, fileOrPath):
"""Open a file
Args:
fileOrPath: Either an object supporting a ``read`` method, an
``os.PathLike`` object, or a string.
"""
self._resources = OrderedDict()
if hasattr(fileOrPath, "read"):
self.file = fileOrPath
else:
try:
# try reading from the resource fork (only works on OS X)
self.file = self.openResourceFork(fileOrPath)
self._readFile()
return
except (ResourceError, IOError):
# if it fails, use the data fork
self.file = self.openDataFork(fileOrPath)
self._readFile()
@staticmethod
def openResourceFork(path):
if hasattr(path, "__fspath__"): # support os.PathLike objects
path = path.__fspath__()
with open(path + "/..namedfork/rsrc", "rb") as resfork:
data = resfork.read()
infile = BytesIO(data)
infile.name = path
return infile
@staticmethod
def openDataFork(path):
with open(path, "rb") as datafork:
data = datafork.read()
infile = BytesIO(data)
infile.name = path
return infile
def _readFile(self):
self._readHeaderAndMap()
self._readTypeList()
def _read(self, numBytes, offset=None):
if offset is not None:
try:
self.file.seek(offset)
except OverflowError:
raise ResourceError("Failed to seek offset ('offset' is too large)")
if self.file.tell() != offset:
raise ResourceError("Failed to seek offset (reached EOF)")
try:
data = self.file.read(numBytes)
except OverflowError:
raise ResourceError("Cannot read resource ('numBytes' is too large)")
if len(data) != numBytes:
raise ResourceError("Cannot read resource (not enough data)")
return data
def _readHeaderAndMap(self):
self.file.seek(0)
headerData = self._read(ResourceForkHeaderSize)
sstruct.unpack(ResourceForkHeader, headerData, self)
# seek to resource map, skip reserved
mapOffset = self.mapOffset + 22
resourceMapData = self._read(ResourceMapHeaderSize, mapOffset)
sstruct.unpack(ResourceMapHeader, resourceMapData, self)
self.absTypeListOffset = self.mapOffset + self.typeListOffset
self.absNameListOffset = self.mapOffset + self.nameListOffset
def _readTypeList(self):
absTypeListOffset = self.absTypeListOffset
numTypesData = self._read(2, absTypeListOffset)
(self.numTypes,) = struct.unpack(">H", numTypesData)
absTypeListOffset2 = absTypeListOffset + 2
for i in range(self.numTypes + 1):
resTypeItemOffset = absTypeListOffset2 + ResourceTypeItemSize * i
resTypeItemData = self._read(ResourceTypeItemSize, resTypeItemOffset)
item = sstruct.unpack(ResourceTypeItem, resTypeItemData)
resType = tostr(item["type"], encoding="mac-roman")
refListOffset = absTypeListOffset + item["refListOffset"]
numRes = item["numRes"] + 1
resources = self._readReferenceList(resType, refListOffset, numRes)
self._resources[resType] = resources
def _readReferenceList(self, resType, refListOffset, numRes):
resources = []
for i in range(numRes):
refOffset = refListOffset + ResourceRefItemSize * i
refData = self._read(ResourceRefItemSize, refOffset)
res = Resource(resType)
res.decompile(refData, self)
resources.append(res)
return resources
def __getitem__(self, resType):
return self._resources[resType]
def __delitem__(self, resType):
del self._resources[resType]
def __setitem__(self, resType, resources):
self._resources[resType] = resources
def __len__(self):
return len(self._resources)
def __iter__(self):
return iter(self._resources)
def keys(self):
return self._resources.keys()
@property
def types(self):
"""A list of the types of resources in the resource fork."""
return list(self._resources.keys())
def countResources(self, resType):
"""Return the number of resources of a given type."""
try:
return len(self[resType])
except KeyError:
return 0
def getIndices(self, resType):
"""Returns a list of indices of resources of a given type."""
numRes = self.countResources(resType)
if numRes:
return list(range(1, numRes + 1))
else:
return []
def getNames(self, resType):
"""Return list of names of all resources of a given type."""
return [res.name for res in self.get(resType, []) if res.name is not None]
def getIndResource(self, resType, index):
"""Return resource of given type located at an index ranging from 1
to the number of resources for that type, or None if not found.
"""
if index < 1:
return None
try:
res = self[resType][index - 1]
except (KeyError, IndexError):
return None
return res
def getNamedResource(self, resType, name):
"""Return the named resource of given type, else return None."""
name = tostr(name, encoding="mac-roman")
for res in self.get(resType, []):
if res.name == name:
return res
return None
def close(self):
if not self.file.closed:
self.file.close()
class Resource(object):
"""Represents a resource stored within a resource fork.
Attributes:
type: resource type.
data: resource data.
id: ID.
name: resource name.
attr: attributes.
"""
def __init__(
self, resType=None, resData=None, resID=None, resName=None, resAttr=None
):
self.type = resType
self.data = resData
self.id = resID
self.name = resName
self.attr = resAttr
def decompile(self, refData, reader):
sstruct.unpack(ResourceRefItem, refData, self)
# interpret 3-byte dataOffset as (padded) ULONG to unpack it with struct
(self.dataOffset,) = struct.unpack(">L", bytesjoin([b"\0", self.dataOffset]))
absDataOffset = reader.dataOffset + self.dataOffset
(dataLength,) = struct.unpack(">L", reader._read(4, absDataOffset))
self.data = reader._read(dataLength)
if self.nameOffset == -1:
return
absNameOffset = reader.absNameListOffset + self.nameOffset
(nameLength,) = struct.unpack("B", reader._read(1, absNameOffset))
(name,) = struct.unpack(">%ss" % nameLength, reader._read(nameLength))
self.name = tostr(name, encoding="mac-roman")
ResourceForkHeader = """
> # big endian
dataOffset: L
mapOffset: L
dataLen: L
mapLen: L
"""
ResourceForkHeaderSize = sstruct.calcsize(ResourceForkHeader)
ResourceMapHeader = """
> # big endian
attr: H
typeListOffset: H
nameListOffset: H
"""
ResourceMapHeaderSize = sstruct.calcsize(ResourceMapHeader)
ResourceTypeItem = """
> # big endian
type: 4s
numRes: H
refListOffset: H
"""
ResourceTypeItemSize = sstruct.calcsize(ResourceTypeItem)
ResourceRefItem = """
> # big endian
id: h
nameOffset: h
attr: B
dataOffset: 3s
reserved: L
"""
ResourceRefItemSize = sstruct.calcsize(ResourceRefItem)