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Re: Calculating differences between the contents of a zip and a directory

by graff (Chancellor)
on Nov 03, 2012 at 05:44 UTC ( #1002076=note: print w/replies, xml ) Need Help??

in reply to Calculating differences between the contents of a zip and a directory

I think the right tool for this job would be Archive::Zip. Here's one way to do what you described - you want to be able to compare file sizes, and when they match, you want to compare the CRC32 values, just to be sure.

(And if you don't want to trust just the file-size and CRC comparisons, it would be easy enough, and some extra run-time, to test if file contents from the zip are equal to (eq) file contents from the directory. But that's probably overkill.)

#!/usr/bin/perl use strict; use Archive::Zip; my $Usage = "$0 [test_path]\n (default test_path is '.')\n"; die $Usage unless ( @ARGV and -f $ARGV[0] ); my $zipfile = shift; my $testpath = shift || '.'; my $zip = Archive::Zip->new( $zipfile ) or die "Archive::Zip was unable to read $zipfile\n"; my ( @missing_from_path, @altered ); for my $member ( $zip->members ) { next if ( $member->isDirectory ); my $filepath = $member->fileName; if ( ! -f "$testpath/$filepath" ) { push @missing_from_path, $filepath; next; } if ( -s _ == $member->uncompressedSize ) { if ( open( my $testfile, '<', "$testpath/$filepath" )) { local $/; $_ = <$testfile>; close $testfile; my $testCRC = $zip->computeCRC32( $_ ); next if ( $testCRC eq $member->crc32 ); } else { warn "Unable to read $testpath/$filepath: $!\n"; } } push @altered, $filepath; } print "Comparing $zipfile to $testpath:\n"; if ( @missing_from_path ) { print " Missing files:\n"; print " $testpath/$_\n" for ( sort @missing_from_path ); } else { print " No files missing\n"; } if ( @altered ) { print " Altered files:\n"; print " $testpath/$_\n" for ( sort @altered ); } else { print " No altered files\n"; } =head1 NAME zip-check -- check zip file against directory contents =head1 SYNOPSIS zip-check [path/to/] [test_path] (default test_path is '.') =head1 DESCRIPTION This script will compare the contents of a given zip file against the contents of a given directory (current working directory by default). We check for two types of differences: - Files in the zip archive that are not found in the directory - Files found in both places, but having different contents (based on comparing their CRC32 values) (We do not report cases where the directory contains files that are not found in the zip archive.) =head1 AUTHOR David Graff <graff at ldc dot upenn dot edu> =cut

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Re^2: Calculating differences between the contents of a zip and a directory
by MilanorTSW (Beadle) on Nov 03, 2012 at 11:05 UTC

    Ah, many thanks.

    Now, I did think it could be possible to just compare sizes, but it wasn't completely trusted.

    I didn't think of CRC comparisons.

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[MidLifeXis]: heh.
[MidLifeXis]: Most likely it is a code that some undocumented system, hidden behind layers of IT, deep in the bowels of the building under the machine room floor, reads that code to keep a presence switch from going off. :-b
[MidLifeXis]: I think I forgot "running on a farm of commodore 64, vic 20s, trs 80s, and apple ]|[e systems"
[GotToBTru]: oh I know what it is .. but it is a number only slightly useful to me and of no possible use to our customer
[MidLifeXis]: Whew - you just saved the free world. <o)
[GotToBTru]: i guess it's a placeholder, the code will only fill it in if there is nothing else to use
[GotToBTru]: but then .. if you have nothing to say, why not say nothing?

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