82 lines
2.0 KiB
Python
82 lines
2.0 KiB
Python
# -*- coding: utf-8 -*-
|
|
"""
|
|
pdfparanoia.parser
|
|
~~~~~~~~~~~~~~~
|
|
|
|
Deals with the existential nature of parsing pdfs.
|
|
|
|
"""
|
|
|
|
try:
|
|
from StringIO import StringIO
|
|
except ImportError: # py3k
|
|
from io import StringIO, BytesIO
|
|
|
|
# Maybe one day pdfquery will be able to save pdf.
|
|
# from pdfquery import PDFQuery
|
|
|
|
import pdfminer.pdfparser
|
|
import pdfminer.pdfdocument
|
|
|
|
from .eraser import replace_object_with
|
|
|
|
def parse_pdf(handler):
|
|
"""
|
|
Parses a PDF via pdfminer.
|
|
"""
|
|
# reset to the beginning of the data
|
|
handler.seek(0)
|
|
|
|
# setup for parsing
|
|
parser = pdfminer.pdfparser.PDFParser(handler)
|
|
doc = pdfminer.pdfdocument.PDFDocument(parser)
|
|
|
|
# actual parsing
|
|
doc.initialize()
|
|
|
|
return doc
|
|
|
|
def parse_content(content):
|
|
"""
|
|
Parses a PDF via pdfminer from a string. There are some problems with
|
|
pdfminer accepting StringIO objects, so this is a temporary hack.
|
|
"""
|
|
stream = StringIO(content)
|
|
return parse_pdf(stream)
|
|
|
|
def deflate(content):
|
|
"""
|
|
Converts all FlateDecode streams into plaintext streams. This significantly
|
|
increases the size of a pdf, but it's useful for debugging and searching
|
|
for how watermarks are implemented.
|
|
|
|
Not all elements are preserved in the resulting document. This is for
|
|
debugging only.
|
|
"""
|
|
# parse the pdf
|
|
pdf = parse_content(content)
|
|
|
|
# get a list of all object ids
|
|
xref = pdf.xrefs[0]
|
|
objids = xref.get_objids()
|
|
|
|
# store new replacements
|
|
replacements = []
|
|
|
|
# scan through each object looking for things to deflate
|
|
for objid in objids:
|
|
obj = pdf.getobj(objid)
|
|
if hasattr(obj, "attrs"):
|
|
if obj.attrs.has_key("Filter") and str(obj.attrs["Filter"]) == "/FlateDecode":
|
|
obj.decode()
|
|
data = obj.data
|
|
if len(data) < 1000:
|
|
replacements.append([objid, data])
|
|
|
|
# apply the replacements to the document
|
|
for (objid, replacement) in replacements:
|
|
content = replace_object_with(content, objid, replacement)
|
|
|
|
return content
|
|
|