6dbed1bf38
all identitical files in the Nix store to each other. (Previously it only computed the size that would be saved by doing so.)
85 lines
1.8 KiB
Perl
Executable file
85 lines
1.8 KiB
Perl
Executable file
#! /usr/bin/perl -w
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use strict;
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use File::Basename;
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my @paths = ("/nix/store");
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print "hashing...\n";
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my $hashList = "/tmp/nix-optimise-hash-list";
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system("find @paths -type f -print0 | xargs -0 md5sum -- > $hashList") == 0
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or die "cannot hash store files";
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print "sorting by hash...\n";
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system("sort $hashList > $hashList.sorted") == 0
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or die "cannot sort list";
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sub atomicLink {
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my $target = shift;
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my $new = shift;
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my $tmpNew = "${new}_optimise.$$";
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# Make the directory writable temporarily.
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my $dir = dirname $new;
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my @st = stat $dir or die;
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chmod ($st[2] | 0200, $dir) or die "cannot make `$dir' writable: $!";
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link $target, $tmpNew or die "cannot create hard link `$tmpNew': $!";
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rename $tmpNew, $new or die "cannot rename `$tmpNew' to `$new': $!";
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chmod ($st[2], $dir) or die "cannot restore permission on `$dir': $!";
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}
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print "hard-linking...\n";
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open LIST, "<$hashList.sorted" or die;
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my $prevFile;
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my $prevHash;
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my $prevInode;
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my $totalSpace = 0;
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my $savedSpace = 0;
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while (<LIST>) {
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/^([0-9a-f]*)\s+(.*)$/ or die;
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my $curFile = $2;
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my $curHash = $1;
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my @st = stat $curFile or die;
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next if ($st[2] & 0222) != 0; # skip writable files
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my $fileSize = $st[7];
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$totalSpace += $fileSize;
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if (defined $prevHash && $curHash eq $prevHash) {
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if ($st[1] != $prevInode) {
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print "$curFile = $prevFile\n";
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atomicLink $prevFile, $curFile;
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$savedSpace += $fileSize;
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}
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} else {
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$prevFile = $curFile;
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$prevHash = $curHash;
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$prevInode = $st[1];
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}
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}
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print "total space = $totalSpace\n";
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print "saved space = $savedSpace\n";
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my $savings = ($savedSpace / $totalSpace) * 100.0;
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print "savings = $savings %\n";
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close LIST;
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