/usr/lib/python2.7/dist-packages/pdfrw/pdfreader.py is in python-pdfrw 0.1-3.
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# Copyright (C) 2006-2009 Patrick Maupin, Austin, Texas
# MIT license -- See LICENSE.txt for details
'''
The PdfReader class reads an entire PDF file into memory and
parses the top-level container objects. (It does not parse
into streams.) The object subclasses PdfDict, and the
document pages are stored in a list in the pages attribute
of the object.
'''
import gc
from pdfrw.errors import PdfParseError, log
from pdfrw.tokens import PdfTokens
from pdfrw.objects import PdfDict, PdfArray, PdfName, PdfObject, PdfIndirect
from pdfrw.uncompress import uncompress
class PdfReader(PdfDict):
warned_bad_stream_start = False # Use to keep from spewing warnings
warned_bad_stream_end = False # Use to keep from spewing warnings
def findindirect(self, objnum, gennum, PdfIndirect=PdfIndirect, int=int):
''' Return a previously loaded indirect object, or create
a placeholder for it.
'''
key = int(objnum), int(gennum)
result = self.indirect_objects.get(key)
if result is None:
self.indirect_objects[key] = result = PdfIndirect(key)
self.deferred_objects.add(key)
result._loader = self.loadindirect
return result
def readarray(self, source, PdfArray=PdfArray):
''' Found a [ token. Parse the tokens after that.
'''
specialget = self.special.get
result = []
pop = result.pop
append = result.append
for value in source:
if value in ']R':
if value == ']':
break
generation = pop()
value = self.findindirect(pop(), generation)
else:
func = specialget(value)
if func is not None:
value = func(source)
append(value)
return PdfArray(result)
def readdict(self, source, PdfDict=PdfDict):
''' Found a << token. Parse the tokens after that.
'''
specialget = self.special.get
result = PdfDict()
next = source.next
tok = next()
while tok != '>>':
if not tok.startswith('/'):
source.exception('Expected PDF /name object')
key = tok
value = next()
func = specialget(value)
if func is not None:
value = func(source)
tok = next()
else:
tok = next()
if value.isdigit() and tok.isdigit():
if next() != 'R':
source.exception('Expected "R" following two integers')
value = self.findindirect(value, tok)
tok = next()
result[key] = value
return result
def empty_obj(self, source, PdfObject=PdfObject):
''' Some silly git put an empty object in the
file. Back up so the caller sees the endobj.
'''
source.floc = source.tokstart
def badtoken(self, source):
''' Didn't see that coming.
'''
source.exception('Unexpected delimiter')
def findstream(self, obj, tok, source, PdfDict=PdfDict, isinstance=isinstance, len=len):
''' Figure out if there is a content stream
following an object, and return the start
pointer to the content stream if so.
(We can't read it yet, because we might not
know how long it is, because Length might
be an indirect object.)
'''
isdict = isinstance(obj, PdfDict)
if not isdict or tok != 'stream':
source.exception("Expected 'endobj'%s token", isdict and " or 'stream'" or '')
fdata = source.fdata
startstream = source.tokstart + len(tok)
gotcr = fdata[startstream] == '\r'
startstream += gotcr
gotlf = fdata[startstream] == '\n'
startstream += gotlf
if not gotlf:
if not gotcr:
source.exception(r'stream keyword not followed by \n')
if not self.warned_bad_stream_start:
source.warning(r"stream keyword terminated by \r without \n")
self.private.warned_bad_stream_start = True
return startstream
def readstream(self, obj, startstream, source,
streamending = 'endstream endobj'.split(), int=int):
fdata = source.fdata
length = int(obj.Length)
source.floc = target_endstream = startstream + length
endit = source.multiple(2)
obj._stream = fdata[startstream:target_endstream]
if endit == streamending:
return
# The length attribute does not match the distance between the
# stream and endstream keywords.
do_warn, self.warned_bad_stream_end = self.warned_bad_stream_end, False
#TODO: Extract maxstream from dictionary of object offsets
# and use rfind instead of find.
maxstream = len(fdata) - 20
endstream = fdata.find('endstream', startstream, maxstream)
source.floc = startstream
room = endstream - startstream
if endstream < 0:
source.error('Could not find endstream')
return
if length == room + 1 and fdata[startstream-2:startstream] == '\r\n':
source.warning(r"stream keyword terminated by \r without \n")
obj._stream = fdata[startstream-1:target_endstream-1]
return
source.floc = endstream
if length > room:
source.error('stream /Length attribute (%d) appears to be too big (size %d) -- adjusting',
length, room)
obj.stream = fdata[startstream:endstream]
return
if fdata[target_endstream:endstream].rstrip():
source.error('stream /Length attribute (%d) might be smaller than data size (%d)',
length, room)
return
endobj = fdata.find('endobj', endstream, maxstream)
if endobj < 0:
source.error('Could not find endobj after endstream')
return
if fdata[endstream:endobj].rstrip() != 'endstream':
source.error('Unexpected data between endstream and endobj')
return
source.error('Illegal endstream/endobj combination')
def loadindirect(self, key):
result = self.indirect_objects.get(key)
if not isinstance(result, PdfIndirect):
return result
source = self.source
offset = int(self.source.obj_offsets.get(key, '0'))
if not offset:
log.warning("Did not find PDF object %s" % (key,))
return None
# Read the object header and validate it
objnum, gennum = key
source.floc = offset
objid = source.multiple(3)
ok = len(objid) == 3
ok = ok and objid[0].isdigit() and int(objid[0]) == objnum
ok = ok and objid[1].isdigit() and int(objid[1]) == gennum
ok = ok and objid[2] == 'obj'
if not ok:
source.floc = offset
source.next()
objheader = '%d %d obj' % (objnum, gennum)
fdata = source.fdata
offset2 = fdata.find('\n' + objheader) + 1 or fdata.find('\r' + objheader) + 1
if not offset2 or fdata.find(fdata[offset2-1] + objheader, offset2) > 0:
source.warning("Expected indirect object '%s'" % objheader)
return None
source.warning("Indirect object %s found at incorrect offset %d (expected offset %d)" %
(objheader, offset2, offset))
source.floc = offset2 + len(objheader)
# Read the object, and call special code if it starts
# an array or dictionary
obj = source.next()
func = self.special.get(obj)
if func is not None:
obj = func(source)
self.indirect_objects[key] = obj
self.deferred_objects.remove(key)
# Mark the object as indirect, and
# add it to the list of streams if it starts a stream
obj.indirect = key
tok = source.next()
if tok != 'endobj':
self.readstream(obj, self.findstream(obj, tok, source), source)
return obj
def findxref(fdata):
''' Find the cross reference section at the end of a file
'''
startloc = fdata.rfind('startxref')
if startloc < 0:
raise PdfParseError('Did not find "startxref" at end of file')
source = PdfTokens(fdata, startloc, False)
tok = source.next()
assert tok == 'startxref' # (We just checked this...)
tableloc = source.next_default()
if not tableloc.isdigit():
source.exception('Expected table location')
if source.next_default().rstrip().lstrip('%') != 'EOF':
source.exception('Expected %%EOF')
return startloc, PdfTokens(fdata, int(tableloc), True)
findxref = staticmethod(findxref)
def parsexref(self, source, int=int, range=range):
''' Parse (one of) the cross-reference file section(s)
'''
fdata = source.fdata
setdefault = source.obj_offsets.setdefault
add_offset = source.all_offsets.append
next = source.next
tok = next()
if tok != 'xref':
source.exception('Expected "xref" keyword')
start = source.floc
try:
while 1:
tok = next()
if tok == 'trailer':
return
startobj = int(tok)
for objnum in range(startobj, startobj + int(next())):
offset = int(next())
generation = int(next())
inuse = next()
if inuse == 'n':
if offset != 0:
setdefault((objnum, generation), offset)
add_offset(offset)
elif inuse != 'f':
raise ValueError
except:
pass
try:
# Table formatted incorrectly. See if we can figure it out anyway.
end = source.fdata.rindex('trailer', start)
table = source.fdata[start:end].splitlines()
for line in table:
tokens = line.split()
if len(tokens) == 2:
objnum = int(tokens[0])
elif len(tokens) == 3:
offset, generation, inuse = int(tokens[0]), int(tokens[1]), tokens[2]
if offset != 0 and inuse == 'n':
setdefault((objnum, generation), offset)
add_offset(offset)
objnum += 1
elif tokens:
log.error('Invalid line in xref table: %s' % repr(line))
raise ValueError
log.warning('Badly formatted xref table')
source.floc = end
source.next()
except:
source.floc = start
source.exception('Invalid table format')
def readpages(self, node):
pagename=PdfName.Page
pagesname=PdfName.Pages
catalogname = PdfName.Catalog
typename = PdfName.Type
kidname = PdfName.Kids
# PDFs can have arbitrarily nested Pages/Page
# dictionary structures.
def readnode(node):
nodetype = node[typename]
if nodetype == pagename:
yield node
elif nodetype == pagesname:
for node in node[kidname]:
for node in readnode(node):
yield node
elif nodetype == catalogname:
for node in readnode(node[pagesname]):
yield node
else:
log.error('Expected /Page or /Pages dictionary, got %s' % repr(node))
try:
return list(readnode(node))
except (AttributeError, TypeError), s:
log.error('Invalid page tree: %s' % s)
return []
def __init__(self, fname=None, fdata=None, decompress=False, disable_gc=True):
# Runs a lot faster with GC off.
disable_gc = disable_gc and gc.isenabled()
try:
if disable_gc:
gc.disable()
if fname is not None:
assert fdata is None
# Allow reading preexisting streams like pyPdf
if hasattr(fname, 'read'):
fdata = fname.read()
else:
try:
f = open(fname, 'rb')
fdata = f.read()
f.close()
except IOError:
raise PdfParseError('Could not read PDF file %s' % fname)
assert fdata is not None
if not fdata.startswith('%PDF-'):
startloc = fdata.find('%PDF-')
if startloc >= 0:
log.warning('PDF header not at beginning of file')
else:
lines = fdata.lstrip().splitlines()
if not lines:
raise PdfParseError('Empty PDF file!')
raise PdfParseError('Invalid PDF header: %s' % repr(lines[0]))
endloc = fdata.rfind('%EOF')
if endloc < 0:
raise PdfParseError('EOF mark not found: %s' % repr(fdata[-20:]))
endloc += 6
junk = fdata[endloc:]
fdata = fdata[:endloc]
if junk.rstrip('\00').strip():
log.warning('Extra data at end of file')
private = self.private
private.indirect_objects = {}
private.deferred_objects = set()
private.special = {'<<': self.readdict,
'[': self.readarray,
'endobj': self.empty_obj,
}
for tok in r'\ ( ) < > { } ] >> %'.split():
self.special[tok] = self.badtoken
startloc, source = self.findxref(fdata)
private.source = source
xref_table_list = []
source.all_offsets = []
while 1:
source.obj_offsets = {}
# Loop through all the cross-reference tables
self.parsexref(source)
tok = source.next()
if tok != '<<':
source.exception('Expected "<<" starting catalog')
newdict = self.readdict(source)
token = source.next()
if token != 'startxref' and not xref_table_list:
source.warning('Expected "startxref" at end of xref table')
# Loop if any previously-written tables.
prev = newdict.Prev
if prev is None:
break
if not xref_table_list:
newdict.Prev = None
original_indirect = self.indirect_objects.copy()
original_newdict = newdict
source.floc = int(prev)
xref_table_list.append(source.obj_offsets)
self.indirect_objects.clear()
if xref_table_list:
for update in reversed(xref_table_list):
source.obj_offsets.update(update)
self.indirect_objects.clear()
self.indirect_objects.update(original_indirect)
newdict = original_newdict
self.update(newdict)
#self.read_all_indirect(source)
private.pages = self.readpages(self.Root)
if decompress:
self.uncompress()
# For compatibility with pyPdf
private.numPages = len(self.pages)
finally:
if disable_gc:
gc.enable()
# For compatibility with pyPdf
def getPage(self, pagenum):
return self.pages[pagenum]
def read_all(self):
deferred = self.deferred_objects
prev = set()
while 1:
new = deferred - prev
if not new:
break
prev |= deferred
for key in new:
self.loadindirect(key)
def uncompress(self):
self.read_all()
uncompress(self.indirect_objects.itervalues())
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