93 lines
2 KiB
Perl
Executable file
93 lines
2 KiB
Perl
Executable file
#! /usr/bin/perl -w
|
|
|
|
use strict;
|
|
use File::Basename;
|
|
|
|
|
|
#my @paths = ("/nix/store");
|
|
my @paths = ("test");
|
|
|
|
|
|
print "hashing...\n";
|
|
|
|
my $hashList = "/tmp/nix-optimise-hash-list";
|
|
|
|
system("find @paths -type f -print0 | xargs -0 md5sum -- > $hashList") == 0
|
|
or die "cannot hash store files";
|
|
|
|
|
|
print "sorting by hash...\n";
|
|
|
|
system("sort $hashList > $hashList.sorted") == 0
|
|
or die "cannot sort list";
|
|
|
|
|
|
sub atomicLink {
|
|
my $target = shift;
|
|
my $new = shift;
|
|
my $tmpNew = "${new}_optimise.$$";
|
|
|
|
# Make the directory writable temporarily.
|
|
my $dir = dirname $new;
|
|
my @st = stat $dir or die;
|
|
|
|
chmod ($st[2] | 0200, $dir) or die "cannot make `$dir' writable: $!";
|
|
|
|
link $target, $tmpNew or die "cannot create hard link `$tmpNew': $!";
|
|
|
|
rename $tmpNew, $new or die "cannot rename `$tmpNew' to `$new': $!";
|
|
|
|
chmod ($st[2], $dir) or die "cannot restore permission on `$dir': $!";
|
|
utime ($st[8], $st[9], $dir) or die "cannot restore timestamp on `$dir': $!";
|
|
}
|
|
|
|
|
|
print "hard-linking...\n";
|
|
|
|
open LIST, "<$hashList.sorted" or die;
|
|
|
|
my $prevFile;
|
|
my $prevHash;
|
|
my $prevInode;
|
|
my $prevExec;
|
|
|
|
my $totalSpace = 0;
|
|
my $savedSpace = 0;
|
|
|
|
while (<LIST>) {
|
|
/^([0-9a-f]*)\s+(.*)$/ or die;
|
|
my $curFile = $2;
|
|
my $curHash = $1;
|
|
|
|
my @st = stat $curFile or die;
|
|
next if ($st[2] & 0222) != 0; # skip writable files
|
|
|
|
my $fileSize = $st[7];
|
|
$totalSpace += $fileSize;
|
|
my $isExec = ($st[2] & 0111) == 0111;
|
|
|
|
if (defined $prevHash && $curHash eq $prevHash
|
|
&& $prevExec == $isExec)
|
|
{
|
|
|
|
if ($st[1] != $prevInode) {
|
|
print "$curFile = $prevFile\n";
|
|
atomicLink $prevFile, $curFile;
|
|
$savedSpace += $fileSize;
|
|
}
|
|
|
|
} else {
|
|
$prevFile = $curFile;
|
|
$prevHash = $curHash;
|
|
$prevInode = $st[1];
|
|
$prevExec = ($st[2] & 0111) == 0111;
|
|
}
|
|
}
|
|
|
|
print "total space = $totalSpace\n";
|
|
print "saved space = $savedSpace\n";
|
|
my $savings = ($savedSpace / $totalSpace) * 100.0;
|
|
print "savings = $savings %\n";
|
|
|
|
close LIST;
|