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)