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Dan Church
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#!/usr/bin/perl
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# vi: et sts=4 sw=4 ts=4
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use strict;
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use warnings;
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our $VERSION = '1.2.2';
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=pod
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=head1 NAME
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simplify_static_dir - optimize directories for size by combining identical
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files
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=head1 SYNOPSIS
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B<simplify_static_dir> [I<OPTIONS>] [I<DIR>]...
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=head1 DESCRIPTION
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The more files this script can process at once, the better. It maintains an
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internal hash of files indexed by their SHA1 checksum. When it finds a
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collision it removes the file with the least amount of file system links, then
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creates a hard link to the other in its place. The larger the number of files
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scanned, the more likely it is that there will be collisions.
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There are failsafes in place, though. If somehow two files' SHA1 checksums are
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identical, but the file sizes do not match, this program will error out (and
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you can go ahead and report the collision; it may be worth money).
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There are other features built in as well. Following the logic that unique
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data, once created has the attribute of being unique of that point in time,
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this script will copy the timestamp of the older file onto the newer file just
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before it makes the hard link. Therefore, many times, simplified directories
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will have the appearance of being older than they actually are.
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From the perspective of any program reading files from the simplified
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directories, the files will lookB<*> and behave the same way as the initial
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state.
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B<*> Except for having an increased number of hard links.
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=head1 OPTIONS
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=over
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=item B<-v>
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Verbose output.
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=item B<-f>
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Print a sum of the number of freed bytes.
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=item B<-m> I<REGEX>
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Only match file paths matching I<REGEX>.
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=item B<-M> I<REGEX>
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Exclude file paths matching I<REGEX>.
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=item B<-s>
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Generate symlinks only.
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=item B<-S>
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Do not generate ANY symlinks.
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=item B<-z>
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Include zero-length files in search. Normally they are ignored (you don't save
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diskspace by hard-linking empty files).
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=item B<--help>
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Output this help message and exit.
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=item B<--version>
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Output version information and exit.
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=back
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By default, scans the current directory. Files not able to be hard-linked are
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symlinked by default.
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=head1 CHANGES
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=over
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=item 1.1.0
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Outputs GNU-style messages (ala `rm -v,' `ln -v,' etc.).
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=item 1.1.1
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Added B<-m> and B<-M> options.
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=item 1.1.2
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Added B<-z> option. Now the default behavior is to not process empty files.
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Because what's the point of freeing up no space?
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=item 1.2.0
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Uses L<Digest::SHA> instead of L<Digest::MD5>. MD5 has been broken.
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=item 1.2.1
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Fixed bug when processing files with \r characters in the name.
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=back
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=head1 COPYRIGHT
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Copyright (C) 2010-2013 Dan Church.
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License GPLv3+: GNU GPL version 3 or later (L<http://gnu.org/licenses/gpl.html>).
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This is free software: you are free to change and redistribute it.
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There is NO WARRANTY, to the extent permitted by law.
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=head1 AUTHOR
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Written by Dan Church S<E<lt>amphetamachine@gmail.comE<gt>>
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=cut
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use File::Find qw/ find /;
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require Digest::SHA;
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use Getopt::Std qw/ getopts /;
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require Pod::Text;
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sub HELP_MESSAGE {
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# my $fh = shift;
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# print $fh <<EOF
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#Usage: $0 [DIRS]
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#Simplify a directory by hard-linking identical files.
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#
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# -v Verbose output.
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# -f Print a sum of the number of freed bytes.
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# -m REGEX Only match file paths matching REGEX.
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# -M REGEX Exclude file paths matching REGEX.
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# -s Generate symlinks only.
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# -S Do not generate ANY symlinks.
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# -z Include zero-length files in search.
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#
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#By default, scans the current directory. Files not able to be hard-linked are
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#symlinked by default.
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#EOF
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#;
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my ($fh, $pod) = (shift, Pod::Text->new);
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$pod->parse_from_file($0, $fh);
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exit 0;
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}
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my %opts = (
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v => 0,
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f => 0,
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m => '',
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M => '',
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s => 0,
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S => 0,
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z => 0,
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);
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&getopts('vfm:M:sSz', \%opts);
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my %files;
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# correct relative paths
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# OR if no directories given, search the current directory
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push @ARGV, $ENV{PWD} unless map { s#^([^/])#$ENV{PWD}/$1# } @ARGV;
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my $freed_bytes = 0;
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&find(\&findexec, @ARGV);
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sub findexec {
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# outright skip directories (don't report skip)
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return if -d $File::Find::name;
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# limit to or exclude file patterns specified by `-m' or `-M',
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# respectively
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# truth table
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# -m matches | -M is used & matches | !return?
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# 0 | 0 | 0
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# 0 | 1 | 0
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# 1 | 0 | 1
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# 1 | 1 | 0
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# note: m// will match everything
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unless ($File::Find::name =~ m/$opts{m}/ and
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!(length $opts{M} and $File::Find::name =~ m/$opts{M}/)) {
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print STDERR "Skipping path `$File::Find::name'\n"
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if $opts{v};
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return;
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}
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# make sure the file exists and it's not a link
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if (-f $File::Find::name && ! -l $File::Find::name) {
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#my $ctx = Digest::MD5->new;
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my $ctx = Digest::SHA->new;
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$ctx->addfile($File::Find::name);
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# save the hex digest because reading the value from
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# Digest::* destroys it
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my $digest = $ctx->hexdigest;
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# organize results from lstat into hash
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my $entry = {};
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(@{$entry}{qw/ name dev ino mode nlink uid gid rdev size
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atime mtime ctime blksize blocks /})
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= ($File::Find::name, lstat $File::Find::name);
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# skip zero-length files if wanted (`-z')
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# truth table:
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# -z | non-zero length | return?
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# 0 | 0 | 1
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# 0 | 1 | 0
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# 1 | 0 | 0
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# 1 | 1 | 0
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return unless $opts{z} or $entry->{size};
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# check to see if we've come across a file with the same crc
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if (exists $files{$digest}) {
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my $curr_entry = $files{$digest};
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# don't waste my time
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return if $curr_entry->{name} eq $entry->{name} or
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$curr_entry->{ino} == $entry->{ino};
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# identical files should be the same size (I'm paranoid
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# of checksumming procedures); if it's not, there's a
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# problem with the checksumming procedure or this
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# script is processing WAY too many files
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# (addendum: perhaps I should congratulate the user on
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# finding a collision in SHA-1)
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if ($curr_entry->{size} != $entry->{size}) {
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die "ERROR: checksums identical for two non-identical files!!!:\n".
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"files:\t`$curr_entry->{name}'\n".
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"\t`$entry->{name}'\n".
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"SHA1: ($digest)\n".
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'(this is probably a limit of SHA1; try processing fewer files)';
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}
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# find the oldest time stamp
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my ($atime, $mtime) = @{(sort
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{$a->{mtime} <=> $b->{mtime}}
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($entry, $curr_entry)
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)[0]}{qw/ atime mtime /};
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# find the file less embedded in the file system
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my ($less_linked, $more_linked) = sort
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{$a->{nlink} <=> $b->{nlink}}
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($entry, $curr_entry);
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# hard-linkable files must exist on the same device and
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# must not already be hard-linked
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if ($curr_entry->{dev} == $entry->{dev} &&
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! $opts{s}) {
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# print "hard-linking $new_file\t=>$old_file\n";
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# attempt to unlink the file
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printf STDERR "removing file `%s'\n",
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$less_linked->{name} if $opts{v};
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unless (unlink $less_linked->{name}) {
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# couldn't do it; try more-linked file
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printf STDERR <<EOF
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Failed to remove file `%s': %s
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(using `%s')
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EOF
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,
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$less_linked->{name},
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$!,
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$more_linked->{name}
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if $opts{v};
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# if we can't do this, there's no point
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# in continuing
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unless (unlink $more_linked->{name}) {
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printf STDERR <<EOF
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Failed to remove file `%s' (second failure on match): %s
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Skipping...
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EOF
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,
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$more_linked->{name},
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$!
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if $opts{v};
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return;
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}
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# the ol' switcheroo
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($more_linked, $less_linked) =
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($less_linked, $more_linked);
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}
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# we unlinked it or failed out
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$freed_bytes += $less_linked->{size}
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unless $less_linked->{nlink} > 1;
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printf STDERR "hard linking `%s' => `%s'\n",
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$less_linked->{name}, $more_linked->{name}
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if $opts{v};
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# hard link the files
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link $more_linked->{name},
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$less_linked->{name};
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# update link count in our hash to reflect the
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# file system (referenced)
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++$more_linked->{nlink};
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# preserve older time stamp
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utime $atime, $mtime, $less_linked->{name};
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} elsif (! $opts{S}) {
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# files are on different drives;
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# most that can be done is to soft-link them
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unless (unlink $less_linked->{name}) {
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# couldn't do it; try more-linked file
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printf STDERR "couldn't remove file `%s' (using `%s')\n",
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$less_linked->{name},
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$more_linked->{name} if $opts{v};
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# if we can't do this, there's no point
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# in continuing
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unlink $more_linked->{name}
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or return;
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# the ol' switcheroo
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($more_linked, $less_linked) =
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($less_linked, $more_linked);
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}
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# we unlinked it or failed out
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$freed_bytes += $less_linked->{size};
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printf STDERR "soft-linking %s => %s\n",
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$less_linked->{name}, $more_linked->{name}
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if $opts{v};
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# create a soft link (TODO: relative links)
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symlink $more_linked->{name},
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$less_linked->{name};
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# preserve older time stamp
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utime $atime, $mtime, $less_linked->{name};
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}
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} else {
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# the file is unique (as far as we know)
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# create a new entry in the hash table
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$files{$digest} = $entry;
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}
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#} elsif (-l $File::Find::name) {
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# # do something to simplify symlinks
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# printf STDERR "FIXME: simplifying symlink `%s'\n",
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# $File::Find::name
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# if $opts{v};
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# printf STDERR "symlink `%s' points to `%s'\n",
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# $File::Find::name, readlink $File::Find::name;
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}
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}
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printf STDERR "freed %d bytes (%0.4G %s)\n",
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$freed_bytes, &hr_size($freed_bytes)
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if $opts{f} or $opts{v};
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sub hr_size {
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my $sz = shift;
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my @sizes = qw/ B KB MB GB TB PB EB ZB YB /;
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my $fact = 1024;
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my $thresh = 0.1;
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my @ret;
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foreach my $exp (reverse 0 .. $#sizes) {
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if ($sz > (1 - $thresh) * $fact ** $exp) {
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@ret = ($sz / $fact ** $exp, $sizes[$exp]);
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last;
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}
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}
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# default to ($sz, 'bytes')
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@ret = ($sz, $sizes[0]) unless @ret;
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wantarray ? @ret : "@ret"
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}
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