[Python-Dev] Re: [Distutils] Questions about distutils strategy

[James C. Ahlstrom]

Tim Peters wrote:
> 
> [James C. Ahlstrom]
> > ...
> > Python seems to lack a CRC-32 function, so I wrote one
>
> Unfortunately, there are many different CRC functions in common use.  None
> belong in md5; if the intent is to support just zip's version, adding a
> (say) zipcrc32 function to binascii would be ok; if we expect to support
> others as well, a new parameterized crc module would be in order.

OK, a CRC-32 in binascii it is.  The CRC-32 I
have comes with these comments which seem to indicate it is a
more "official standard" CRC-32 than average:

# *  Crc - 32 BIT ANSI X3.66 CRC checksum files
#*********************************************************************\
#*                                                                    *|
#* Demonstration program to compute the 32-bit CRC used as the frame  *|
#* check sequence in ADCCP (ANSI X3.66, also known as FIPS PUB 71     *|
#* and FED-STD-1003, the U.S. versions of CCITT's X.25 link-level     *|
#* protocol).  The 32-bit FCS was added via the Federal Register,     *|
#* 1 June 1982, p.23798.  I presume but don't know for certain that   *|
#* this polynomial is or will be included in CCITT V.41, which        *|
#* defines the 16-bit CRC (often called CRC-CCITT) polynomial.  FIPS  *|
#* PUB 78 says that the 32-bit FCS reduces otherwise undetected       *|
#* errors by a factor of 10^-5 over 16-bit FCS.                       *|
#*                                                                    *|
#*********************************************************************
#* Copyright (C) 1986 Gary S. Brown.  You may use this program, or
#* code or tables extracted from it, as desired without restriction.
 
I can submit this as a patch to binascii, or if the Copyright bothers
anyone, maybe it is better for Guido to use his CRC-32 from his ZIP
code.  Preference?

> > I can't seem to get WinZip to record a partial path.  That is,
>
> dialog box, you need to cd to the *Lib* directory, check the "Save extra
> folder info" box, and then, e.g.,

Thanks.  I knew there had to be some magic incantation to do it.
 
> 6. Use a comand-line zip tool instead (e.g., pkzip; I think WinZip has
>    an "experimental" cmdline add-on too, but haven't tried it).

Actually pkzip 2.04g doesn't work because it writes names in upper case
and is limited to 8.3 names (I think).  My zipfile.py can be used as
a basis for a command line tool.  Actually I use makefiles with imbedded
Python programs and find this easier than command line tools.

JimA