Assertion Error in Pypdf package in Python

Question

I am using Python 2.4 and PyPdf 1.13 on a Windows platform. I am trying to merge PDF files from a list into one using the following code:

import os
from pyPdf import PdfFileWriter, PdfFileReader

attached=["C:\\test\\T_tech.pdf","C:\\test\\00647165-Backup.pdf"]
output=PdfFileWriter()
maxpage=0

os.chdir("C:\\test")
name= attached[0]
name = os.path.basename(name).split('.')[0]

for nam in attached:
   input= PdfFileReader(file(nam,"rb"))  
   maxpage=input.getNumPages()
   for i in range(0,maxpage):
     output.addPage(input.getPage(i))

outputStream =file("Output-"+name+".pdf","wb")
output.write(outputStream)
outputStream.close()

I am getting the following error when I run this code.

  Traceback (most recent call last):
    File "C:\Python24\pdfmerge.py", line 13, in ?
       input= PdfFileReader(file(nam,"rb"))
    File "C:\Python24\Lib\site-packages\pyPdf\pdf.py", line 374, in __init__
       self.read(stream)
    File "C:\Python24\Lib\site-packages\pyPdf\pdf.py", line 847, in read
       assert False
  AssertionError

Any help is greatly appreciated.

Answer 1

From the source:

            # bad xref character at startxref.  Let's see if we can find
            # the xref table nearby, as we've observed this error with an
            # off-by-one before.
            stream.seek(-11, 1)
            tmp = stream.read(20)
            xref_loc = tmp.find("xref")
            if xref_loc != -1:
                startxref -= (10 - xref_loc)
                continue
            else:
                # no xref table found at specified location
                assert False
                break

You're hitting that latter "no cross reference table found..." condition. Try patching the source, omitting the assertion and see if it still works.