def _read_trailer(self, src: io.IOBase,
tok: HighLevelTokenizer) -> Dictionary:
# return None if there is no trailer
token = tok.next_non_comment_token()
assert token is not None
if token.text != "trailer":
return Dictionary()
# if there is a keyword "trailer" the next token should be TokenType.START_DICT
token = tok.next_non_comment_token()
assert token is not None
if token.token_type != TokenType.START_DICT:
raise PDFSyntaxError(
byte_offset=tok.tell(),
message="invalid XREF trailer",
)
# go back 2 chars "<<"
src.seek(-2, io.SEEK_CUR)
# read dictionary as trailer
trailer_dict = tok.read_dictionary()
# process startxref
token = tok.next_non_comment_token()
assert token is not None
if token.token_type != TokenType.OTHER or token.text != "startxref":
raise PDFSyntaxError(
byte_offset=token.byte_offset,
message="start of XREF not found",
)
# return
return trailer_dict
def _seek_to_xref_token(self, src: io.IOBase, tok: HighLevelTokenizer):
# find "startxref" text
start_of_xref_token_byte_offset = self._find_backwards(
src, tok, "startxref")
assert start_of_xref_token_byte_offset is not None
if start_of_xref_token_byte_offset == -1:
raise StartXREFTokenNotFoundError()
# set tokenizer to "startxref"
src.seek(start_of_xref_token_byte_offset)
token = tok.next_non_comment_token()
assert token is not None
if token.text == "xref":
src.seek(start_of_xref_token_byte_offset)
return
# if we are at startxref, we are reading the XREF table backwards
# and we need to go back to the start of XREF
if token.text == "startxref":
token = tok.next_non_comment_token()
assert token is not None
if token.token_type != TokenType.NUMBER:
raise PDFSyntaxError(byte_offset=token.byte_offset,
message="invalid XREF")
start_of_xref_offset = int(token.text)
src.seek(start_of_xref_offset)
def _read_section(self, src: io.IOBase,
tok: HighLevelTokenizer) -> List[Reference]:
tokens = [tok.next_non_comment_token() for _ in range(0, 2)]
assert tokens[0] is not None
assert tokens[1] is not None
if tokens[0].text in ["trailer", "startxref"]:
src.seek(tokens[0].byte_offset)
return []
if tokens[0].token_type != TokenType.NUMBER:
raise PDFValueError(
byte_offset=tokens[0].byte_offset,
expected_value_description="number",
received_value_description=tokens[0].text,
)
if tokens[1].token_type != TokenType.NUMBER:
raise PDFValueError(
byte_offset=tokens[1].byte_offset,
expected_value_description="number",
received_value_description=tokens[1].text,
)
start_object_number = int(tokens[0].text)
number_of_objects = int(tokens[1].text)
indirect_references = []
# read subsection
for i in range(0, number_of_objects):
tokens = [tok.next_non_comment_token() for _ in range(0, 3)]
assert tokens[0] is not None
assert tokens[1] is not None
assert tokens[2] is not None
if tokens[0].text in ["trailer", "startxref"]:
raise PDFSyntaxError(
byte_offset=tokens[0].byte_offset,
message="unexpected EOF while processing XREF",
)
if (tokens[0].token_type != TokenType.NUMBER
or tokens[1].token_type != TokenType.NUMBER
or tokens[2].token_type != TokenType.OTHER
or tokens[2].text not in ["f", "n"]):
raise PDFSyntaxError(
byte_offset=tokens[0].byte_offset,
message="invalid XREF line",
)
indirect_references.append(
Reference(
object_number=start_object_number + i,
byte_offset=int(tokens[0].text),
generation_number=int(tokens[1].text),
is_in_use=(tokens[2].text == "n"),
))
# return
return indirect_references
def _find_backwards(
self,
src: io.IOBase,
tok: HighLevelTokenizer,
text_to_find: str,
) -> int:
# length of str to check
str_len = 1024
# go to end of file
src.seek(0, io.SEEK_END)
file_length = src.tell()
pos = file_length - str_len
if pos < 1:
pos = 1
while pos > 0:
src.seek(pos)
bytes_near_eof = "".join(
[tok._next_char() for _ in range(0, str_len)])
idx = bytes_near_eof.find(text_to_find)
if idx >= 0:
return pos + idx
pos = pos - str_len + len(text_to_find)
# raise error
return -1
def read(
self,
src: io.IOBase,
tok: HighLevelTokenizer,
initial_offset: Optional[int] = None,
) -> "XREF":
if initial_offset is not None:
src.seek(initial_offset)
else:
self._seek_to_xref_token(src, tok)
# now we should be back to the start of XREF
token = tok.next_non_comment_token()
assert token is not None
if token.text != "xref":
raise XREFTokenNotFoundError()
# read xref sections
while True:
xref_section = self._read_section(src, tok)
if len(xref_section) == 0:
break
else:
for r in xref_section:
self.append(r)
# process trailer
self["Trailer"] = self._read_trailer(src, tok)
# return self
return self
def read(self, cmap_bytes: str) -> "CMap":
N = len(cmap_bytes)
tok = HighLevelTokenizer(io.BytesIO(cmap_bytes.encode("latin-1")))
prev_token = None
while tok.tell() < N:
token = tok.next_non_comment_token()
if token is None:
break
# beginbfchar
if token.text == "beginbfchar":
n = int(prev_token.text)
for j in range(0, n):
c = self._hex_string_to_int_or_tuple(tok.read_object())
uc = self._hex_string_to_int_or_tuple(tok.read_object())
self._add_symbol(c, uc)
continue
# beginbfrange
if token.text == "beginbfrange":
n = int(prev_token.text)
for j in range(0, n):
c_start_token = tok.read_object()
c_start = int(c_start_token, 16)
c_end_token = tok.read_object()
c_end = int(c_end_token, 16)
tmp = tok.read_object()
if isinstance(tmp, HexadecimalString):
uc = self._hex_string_to_int_or_tuple(tmp)
for k in range(0, c_end - c_start + 1):
if isinstance(uc, int):
self._add_symbol(c_start + k, uc + k)
elif isinstance(uc, tuple):
self._add_symbol(c_start + k,
(uc[0], uc[1] + k))
elif isinstance(tmp, list):
for k in range(0, c_end - c_start + 1):
uc = self._hex_string_to_int_or_tuple(tmp[k])
self._add_symbol(c_start + k, uc)
# default
prev_token = token
return self
def transform(
self,
object_to_transform: Union[io.BufferedIOBase, io.RawIOBase,
AnyPDFType],
parent_object: Any,
context: Optional[TransformerContext] = None,
event_listeners: typing.List[EventListener] = [],
) -> Any:
# update context
assert context is not None
assert isinstance(object_to_transform,
io.BufferedIOBase) or isinstance(
object_to_transform, io.RawIOBase)
context.root_object = Document()
context.source = object_to_transform
context.tokenizer = HighLevelTokenizer(context.source)
# add listener(s)
for l in event_listeners:
context.root_object.add_event_listener(l)
# remove prefix
self._remove_prefix(context)
# check header
self._check_header(context)
# file size
context.source.seek(0, os.SEEK_END)
file_length = context.source.tell()
context.source.seek(0)
context.root_object["FileSize"] = Decimal(file_length)
# build XREF object
self._read_xref(context)
# transform trailer dictionary
xref = context.root_object.get("XRef")
if "Trailer" in xref and "Encrypt" in xref["Trailer"]:
# TODO
raise NotImplementedError(
"password-protected PDFs are currently not supported")
trailer = self.get_root_transformer().transform(
context.root_object["XRef"]["Trailer"],
context.root_object,
context,
[],
)
xref["Trailer"] = trailer
for k in ["DecodeParms", "Filter", "Index", "Length", "Prev", "W"]:
if k in xref["Trailer"]:
xref["Trailer"].pop(k)
# return
return context.root_object
def read(
self,
io_source: Union[io.BufferedIOBase, io.RawIOBase],
tokenizer: HighLevelTokenizer,
initial_offset: Optional[int] = None,
) -> "XREF":
if initial_offset is not None:
io_source.seek(initial_offset)
else:
self._seek_to_xref_token(io_source, tokenizer)
xref_stream = tokenizer.read_object()
assert isinstance(xref_stream, Stream)
# check widths
assert "W" in xref_stream
assert all([
isinstance(xref_stream["W"][x], Decimal)
for x in range(0, len(xref_stream["W"]))
])
# decode widths
widths = [
int(xref_stream["W"][x]) for x in range(0, len(xref_stream["W"]))
]
total_entry_width = sum(widths)
# parent
document = self.get_root() # type: ignore [attr-defined]
# list of references
indirect_references = [
Reference(
object_number=0,
generation_number=65535,
is_in_use=False,
document=document,
)
]
# check size
assert "Size" in xref_stream
assert isinstance(xref_stream["Size"], Decimal)
# get size
number_of_objects = int(xref_stream["Size"])
# index
index = []
if "Index" in xref_stream:
index = xref_stream["Index"]
assert isinstance(index, List)
assert len(index) % 2 == 0
assert isinstance(index[0], Decimal)
assert isinstance(index[1], Decimal)
else:
index = [Decimal(0), Decimal(number_of_objects)]
# apply filters
xref_stream = decode_stream(xref_stream)
# read every range specified in \Index
xref_stream_decoded_bytes = xref_stream["DecodedBytes"]
for idx in range(0, len(index), 2):
start = int(index[idx])
length = int(index[idx + 1])
bptr = 0
for i in range(0, length):
# object number
object_number = start + i
# read type
type = 1
if widths[0] > 0:
type = 0
for j in range(0, widths[0]):
type = (type << 8) + (xref_stream_decoded_bytes[bptr]
& 0xFF)
bptr += 1
# read field 2
field2 = 0
for j in range(0, widths[1]):
field2 = (field2 << 8) + (xref_stream_decoded_bytes[bptr]
& 0xFF)
bptr += 1
# read field 3
field3 = 0
for j in range(0, widths[2]):
field3 = (field3 << 8) + (xref_stream_decoded_bytes[bptr]
& 0xFF)
bptr += 1
# check type
assert type in [0, 1, 2]
pdf_indirect_reference = None
if type == 0:
# type :The type of this entry, which shall be 0. Type 0 entries define
# the linked list of free objects (corresponding to f entries in a
# cross-reference table).
# field2 : The object number of the next free object
# field3 : The generation number to use if this object number is used again
pdf_indirect_reference = Reference(
document=document,
object_number=object_number,
byte_offset=field2,
generation_number=field3,
is_in_use=False,
)
if type == 1:
# Type : The type of this entry, which shall be 1. Type 1 entries define
# objects that are in use but are not compressed (corresponding
# to n entries in a cross-reference table).
# field2 : The byte offset of the object, starting from the beginning of the
# file.
# field3 : The generation number of the object. Default value: 0.
pdf_indirect_reference = Reference(
document=document,
object_number=object_number,
byte_offset=field2,
generation_number=field3,
)
if type == 2:
# Type : The type of this entry, which shall be 2. Type 2 entries define
# compressed objects.
# field2 : The object number of the object stream in which this object is
# stored. (The generation number of the object stream shall be
# implicitly 0.)
# field3 : The index of this object within the object stream.
pdf_indirect_reference = Reference(
document=document,
object_number=object_number,
generation_number=0,
parent_stream_object_number=field2,
index_in_parent_stream=field3,
)
assert pdf_indirect_reference is not None
# append
existing_indirect_ref = next(
iter([
x for x in indirect_references
if x.object_number is not None
and x.object_number == Decimal(object_number)
]),
None,
)
ref_is_in_reading_state = (
existing_indirect_ref is not None
and existing_indirect_ref.is_in_use
and existing_indirect_ref.generation_number
== pdf_indirect_reference.generation_number)
ref_is_first_encountered = existing_indirect_ref is None or (
not ref_is_in_reading_state
and existing_indirect_ref.document is None)
if ref_is_first_encountered:
assert pdf_indirect_reference is not None
indirect_references.append(pdf_indirect_reference)
elif ref_is_in_reading_state:
assert existing_indirect_ref is not None
assert pdf_indirect_reference is not None
existing_indirect_ref.index_in_parent_stream = (
pdf_indirect_reference.index_in_parent_stream)
existing_indirect_ref.parent_stream_object_number = (
pdf_indirect_reference.parent_stream_object_number)
# add section
for r in indirect_references:
self.append(r)
# initialize trailer
self["Trailer"] = Dictionary(xref_stream)
# return
return self
def read(self, io_source: io.IOBase) -> "Canvas":
io_source.seek(0, os.SEEK_END)
length = io_source.tell()
io_source.seek(0)
canvas_tokenizer = HighLevelTokenizer(io_source)
# process content
operand_stk = []
while canvas_tokenizer.tell() != length:
# attempt to read object
obj = canvas_tokenizer.read_object()
if obj is None:
break
# push argument onto stack
if not isinstance(obj, CanvasOperatorName):
operand_stk.append(obj)
continue
# process operator
candidate_ops = [
x for x in self.canvas_operators if x.get_text() == str(obj)
]
if len(candidate_ops) == 1:
operator = candidate_ops[0]
if len(operand_stk) < operator.get_number_of_operands():
# if we are in a compatibility section ignore any possible mistake
if self.in_compatibility_section:
continue
raise IllegalGraphicsStateError(
message="Unable to execute operator %s. Expected %d arguments, received %d."
% (
operator.text,
operator.get_number_of_operands(),
len(operand_stk),
)
)
operands = []
for _ in range(0, operator.get_number_of_operands()):
operands.insert(0, operand_stk.pop(-1))
# append
if "Instructions" not in self:
self["Instructions"] = List().set_parent(self)
instruction_number = len(self["Instructions"])
instruction_dictionary = Dictionary()
instruction_dictionary["Name"] = operator.get_text()
instruction_dictionary["Args"] = List().set_parent(
instruction_dictionary
)
if len(operands) > 0:
for i in range(0, len(operands)):
instruction_dictionary["Args"].append(operands[i])
self["Instructions"].append(instruction_dictionary)
# debug
logger.debug(
"%d %s %s"
% (
instruction_number,
operator.text,
str([str(x) for x in operands]),
)
)
# invoke
try:
operator.invoke(self, operands)
except Exception as e:
if not self.in_compatibility_section:
raise e
# unknown operator
if len(candidate_ops) == 0:
# print("Missing OPERATOR %s" % obj)
pass
# return
return self
def get(
self,
indirect_reference: Union[Reference, int],
src: io.IOBase,
tok: HighLevelTokenizer,
) -> Optional[AnyPDFType]:
# cache
obj = None
# lookup Reference object for int
if isinstance(indirect_reference, int) or isinstance(
indirect_reference, Decimal):
refs = [
x for x in self.entries
if x.object_number == int(indirect_reference)
]
if len(refs) == 0:
return None
indirect_reference = refs[0]
# lookup Reference (in self) for Reference
elif isinstance(indirect_reference, Reference):
refs = [
x for x in self.entries
if x.object_number == indirect_reference.object_number
]
if len(refs) == 0:
return None
indirect_reference = refs[0]
# reference points to an object that is not in use
assert isinstance(indirect_reference, Reference)
if not indirect_reference.is_in_use:
obj = None
# the indirect reference may have a byte offset
if indirect_reference.byte_offset is not None:
byte_offset = int(indirect_reference.byte_offset)
tell_before = tok.tell()
tok.seek(byte_offset)
obj = tok.read_object(xref=self)
tok.seek(tell_before)
# entry specifies a parent object
if indirect_reference.parent_stream_object_number is not None:
stream_object = self.get(
indirect_reference.parent_stream_object_number, src, tok)
assert isinstance(stream_object, dict)
if "Length" not in stream_object:
raise PDFTypeError(expected_type=Union[Decimal, Reference],
received_type=None)
if "First" not in stream_object:
raise PDFTypeError(expected_type=Union[Decimal, Reference],
received_type=None)
# Length may be Reference
if isinstance(stream_object["Length"], Reference):
stream_object["Length"] = self.get(stream_object["Length"],
src=src,
tok=tok)
# First may be Reference
if isinstance(stream_object["First"], Reference):
stream_object["First"] = self.get(stream_object["First"],
src=src,
tok=tok)
first_byte = int(stream_object.get("First", 0))
if "DecodedBytes" not in stream_object:
try:
stream_object = decode_stream(stream_object)
except Exception as ex:
logger.debug(
"unable to inflate stream for object %d" %
indirect_reference.parent_stream_object_number)
raise ex
stream_bytes = stream_object["DecodedBytes"][first_byte:]
# tokenize parent stream
index = int(indirect_reference.index_in_parent_stream)
length = int(stream_object["Length"])
if index < length:
tok = HighLevelTokenizer(io.BytesIO(stream_bytes))
obj = [tok.read_object() for x in range(0, index + 1)]
obj = obj[-1]
else:
obj = None
# return
return obj
def read(self, io_source: io.IOBase) -> "Canvas":
io_source.seek(0, os.SEEK_END)
length = io_source.tell()
io_source.seek(0)
canvas_tokenizer = HighLevelTokenizer(io_source)
# process content
operand_stk = []
while canvas_tokenizer.tell() != length:
# print("<canvas pos='%d' length='%d' percentage='%d'/>" % ( canvas_tokenizer.tell(), length, int(canvas_tokenizer.tell() * 100 / length)))
# attempt to read object
obj = canvas_tokenizer.read_object()
if obj is None:
break
# push argument onto stack
if not isinstance(obj, CanvasOperatorName):
operand_stk.append(obj)
continue
# process operator
operator = self.canvas_operators.get(obj, None)
if operator is None:
logger.debug("Missing operator %s" % obj)
continue
if not self.in_compatibility_section:
assert len(operand_stk) >= operator.get_number_of_operands()
operands: typing.List["CanvasOperator"] = [] # type: ignore [name-defined]
for _ in range(0, operator.get_number_of_operands()):
operands.insert(0, operand_stk.pop(-1))
# append
if "Instructions" not in self:
self["Instructions"] = List().set_parent(self) # type: ignore [attr-defined]
instruction_number = len(self["Instructions"])
instruction_dictionary = Dictionary()
instruction_dictionary["Name"] = operator.get_text()
instruction_dictionary["Args"] = List().set_parent( # type: ignore [attr-defined]
instruction_dictionary
)
if len(operands) > 0:
for i in range(0, len(operands)):
instruction_dictionary["Args"].append(operands[i])
self["Instructions"].append(instruction_dictionary)
# debug
logger.debug(
"%d %s %s"
% (
instruction_number,
operator.text,
str([str(x) for x in operands]),
)
)
# invoke
try:
operator.invoke(self, operands)
except Exception as e:
if not self.in_compatibility_section:
raise e
# return
return self
