Re-write script
Breaking changes: * Remove support for symlink generation. Bugs fixed: * SHA-1 hash collisions no longer corrupt yer data. Internal changes: * Rework into a helper package
This commit is contained in:
Dan Church
parent
c6beadda5f
commit
79e3eca2cb
GPG Key ID:
EA2BF379CD2CDBD0
10
CHANGELOG.md
10
CHANGELOG.md
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@ -4,6 +4,16 @@ All notable changes to this project will be documented in this file.
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## [Unreleased]
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## [2.0.0]
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### Fixed
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- SHA1 collisions no longer corrupt yer data
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### Changed
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- Remove support for symlink generation
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## [1.2.1]
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- Fixed bug when processing files with \r characters in the name
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@ -3,7 +3,7 @@
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use strict;
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use warnings;
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our $VERSION = '1.2.3';
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our $VERSION = '2.0.0';
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=pod
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@ -60,14 +60,6 @@ Only match file paths matching 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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@ -83,8 +75,7 @@ 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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By default, scans the current directory.
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=head1 COPYRIGHT
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@ -107,27 +98,22 @@ require Digest::SHA;
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use Getopt::Std qw/ getopts /;
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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: $0 [DIRS]
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#Simplify a directory by hard-linking identical files.
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#
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# -v Verbose output.
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# -f Print a sum of the number of freed bytes.
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# -m REGEX Only match file paths matching REGEX.
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# -M REGEX Exclude file paths matching REGEX.
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# -s Generate symlinks only.
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# -S Do not generate ANY symlinks.
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# -z Include zero-length files in search.
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#
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#By default, scans the current directory. Files not able to be hard-linked are
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#symlinked by default.
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#EOF
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#;
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require Pod::Text;
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my ($fh, $pod) = (shift, Pod::Text->new);
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$pod->parse_from_file($0, $fh);
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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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-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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-z Include zero-length files in search.
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By default, scans the current directory.
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See also `perldoc $0'
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EOF
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;
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exit 0;
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}
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@ -136,14 +122,16 @@ my %opts = (
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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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&getopts('vfm:M:z', \%opts);
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my %files;
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my $filehash = new Directory::Simplify::FileHash;
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# include zero-length files if wanted (`-z')
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$filehash->min_linkable_size(0)
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if $opts{z};
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# correct relative paths
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# OR if no directories given, search the current directory
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@ -153,6 +141,10 @@ my $freed_bytes = 0;
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&find(\&findexec, @ARGV);
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printf STDERR "freed %d bytes (%0.4G %s)\n",
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$freed_bytes, &hr_size($freed_bytes)
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if $opts{f} or $opts{v};
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sub 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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@ -180,165 +172,87 @@ sub findexec {
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return;
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}
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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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my $entry = $filehash->make_entry($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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return unless $opts{z} or $entry->{size};
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# check to see if we've come across a file with the same checksum
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unless (exists $files{$digest}) {
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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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return;
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my @linkable = $filehash->find_hardlinkable($entry);
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if (@linkable) {
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&hardlink_entries($entry, @linkable);
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}
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$filehash->add_entry($entry);
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}
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my $curr_entry = $files{$digest};
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sub hardlink_entries {
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my ($entry, @linkable) = @_;
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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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# only one of the linkable entries should suffice
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my $linking_with = $linkable[0];
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# identical files should be the same size (I'm paranoid
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# of checksumming procedures); if it's not, there's a
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# problem with the checksumming procedure or this
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# script is processing WAY too many files
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# (addendum: perhaps I should congratulate the user on
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# finding a collision in SHA-1)
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if ($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, $curr_entry)
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# calculate the timestamp of the resulting file
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my ($atime, $mtime) = @{(
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$filehash->oldest_mtime($entry, $linking_with)
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)[0]}{qw/ atime mtime /};
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# find the file less embedded in the file system
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my ($less_linked, $more_linked) = sort
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{$a->{nlink} <=> $b->{nlink}}
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($entry, $curr_entry);
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my ($less_linked, $more_linked) = $filehash->less_linked($entry, $linking_with);
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# hard-linkable files must exist on the same device and
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# must not already be hard-linked
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if ($curr_entry->{dev} == $entry->{dev} &&
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! $opts{s}) {
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# attempt to unlink the file
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printf STDERR "removing file `%s'\n",
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$less_linked->{name} if $opts{v};
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unless (unlink $less_linked->{name}) {
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# couldn't do it; try more-linked file
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printf STDERR "Failed to remove file `%s': %s\n(using `%s')\n",
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$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 $more_linked->{name}) {
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printf STDERR "Failed to remove file `%s' (second failure on match): %s\nSkipping...\n",
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$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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printf STDERR "removing file `%s'\n", $less_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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unless (unlink $less_linked->{name}) {
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printf STDERR "Failed to remove file `%s': %s\n(using `%s')\n",
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$less_linked->{name},
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$more_linked->{name} if $opts{v};
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$!,
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$more_linked->{name};
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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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# if we can't do this, there's no point in continuing
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unless (unlink $more_linked->{name}) {
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printf STDERR "Failed to remove file `%s' (second failure on match): %s\nSkipping...\n",
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$more_linked->{name},
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$!;
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return;
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}
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# we unlinked it or failed out
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$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, $less_linked->{name};
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# the ol' switcheroo
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($more_linked, $less_linked) =
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($less_linked, $more_linked);
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}
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#} 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 $File::Find::name;
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# we unlinked it or failed out
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$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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# preserve older time stamp
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utime $atime, $mtime, $more_linked->{name};
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$more_linked->{atime} = $atime;
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$more_linked->{mtime} = $mtime;
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# update link count in our hash to reflect the file system (referenced)
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++$more_linked->{nlink};
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# update old entry with the info from the new one
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foreach my $copy_attr (qw/
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ino
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nlink
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mode
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uid
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gid
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atime
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mtime
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ctime
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/) {
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$less_linked->{$copy_attr} = $more_linked->{$copy_attr};
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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 $sz = shift;
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my @sizes = qw/ B KB MB GB TB PB EB ZB YB /;
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@ -357,3 +271,206 @@ sub hr_size {
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wantarray ? @ret : "@ret"
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}
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package Directory::Simplify::FileHash;
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use strict;
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use warnings;
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=head1 DESCRIPTION
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Object for abstracting management of a hashed filesystem
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=cut
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sub new {
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my ($class, $self) = (shift, {});
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$self->{_files} = {};
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require Digest::SHA;
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$self->{_ctx} = Digest::SHA->new;
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# default options
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$self->{_min_linkable_size} = 1;
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bless $self, $class
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}
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=head2 min_linkable_size($bytes)
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Set or get the minimum size of files to be considered hard-linkable. Default is 1.
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=cut
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sub min_linkable_size {
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my $self = shift;
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my $in = shift;
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if (defined $in) {
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$self->{_min_linkable_size} = $in;
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}
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$self->{_min_linkable_size}
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}
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=head2 make_entry($filename)
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=cut
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sub make_entry {
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my $self = shift;
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my ($filename) = @_;
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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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= ($filename, lstat $filename);
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$entry->{hash} = $self->_hash($filename);
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$entry
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}
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=head2 add_entry($entry)
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=cut
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sub add_entry {
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my $self = shift;
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my ($entry) = @_;
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my $hash = $entry->{hash};
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unless (defined $self->{_files}->{$hash}) {
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$self->{_files}->{$hash} = [];
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}
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push @{$self->{_files}->{$hash}}, $entry;
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}
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sub find_hardlinkable {
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my $self = shift;
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my ($entry) = @_;
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my $hash = $entry->{hash};
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|
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# no matching entries
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unless (defined $self->{_files}->{$hash}) {
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return ();
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}
|
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|
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my @matches;
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foreach my $ent (@{$self->{_files}->{$hash}}) {
|
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if ($self->_entries_are_hard_linkable($entry, $ent)) {
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push @matches, $ent;
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}
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}
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return @matches;
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}
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=head2 oldest($entry_a, $entry_b, ...)
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Find the file less embedded in the file system.
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=cut
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sub less_linked {
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my $self = shift;
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return sort
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{$a->{nlink} <=> $b->{nlink}}
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@_;
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}
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=head2 oldest($entry_a, $entry_b, ...)
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Find the entry with the oldest time stamp.
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=cut
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sub oldest_mtime {
|
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my $self = shift;
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return sort
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{$a->{mtime} <=> $b->{mtime}}
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@_;
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}
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sub _hash {
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my $self = shift;
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my ($filename) = @_;
|
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$self->{_ctx}->addfile($filename);
|
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return $self->{_ctx}->hexdigest;
|
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}
|
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|
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sub _entries_are_hard_linkable {
|
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my $self = shift;
|
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my ($entry_a, $entry_b) = @_;
|
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|
||||
# obviously, if the sizes aren't the same, they're not the same file
|
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unless (&_entries_sizes_match($entry_a, $entry_b)) {
|
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return 0;
|
||||
}
|
||||
|
||||
# too small to be hard-linked
|
||||
if ($entry_a->{size} < $self->min_linkable_size) {
|
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return 0;
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}
|
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|
||||
# they're the same file, don't try it
|
||||
if (&_entries_are_same_filename($entry_a, $entry_b)) {
|
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return 0;
|
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}
|
||||
if (&_entries_are_already_hard_linked($entry_a, $entry_b)) {
|
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return 0;
|
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}
|
||||
|
||||
if (&_entries_contents_match($entry_a, $entry_b)) {
|
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return 1;
|
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}
|
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return 0;
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||||
}
|
||||
|
||||
sub _entries_are_same_filename {
|
||||
my ($entry_a, $entry_b) = @_;
|
||||
|
||||
if ($entry_a->{name} eq $entry_b->{name}) {
|
||||
return 1;
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
sub _entries_are_already_hard_linked {
|
||||
my ($entry_a, $entry_b) = @_;
|
||||
|
||||
if ($entry_a->{ino} == $entry_b->{ino} and
|
||||
$entry_a->{dev} == $entry_b->{dev}) {
|
||||
return 1;
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
sub _entries_sizes_match {
|
||||
my ($entry_a, $entry_b) = @_;
|
||||
if ($entry_a->{size} != $entry_b->{size}) {
|
||||
return 0;
|
||||
}
|
||||
return 1;
|
||||
}
|
||||
|
||||
sub _entries_contents_match {
|
||||
my ($entry_a, $entry_b) = @_;
|
||||
|
||||
# also, if the hashes aren't the same, they cannot be the same file
|
||||
if ($entry_a->{hash} ne $entry_b->{hash}) {
|
||||
return 0;
|
||||
}
|
||||
|
||||
use File::Compare qw/ compare /;
|
||||
my $contents_same = (0 == &compare($entry_a->{name}, $entry_b->{name}));
|
||||
|
||||
# warn about hash collision
|
||||
unless ($contents_same) {
|
||||
warn "Hash collision between files:\n* $entry_a->{name}\n* $entry_b->{name}\n (don't panic)\n";
|
||||
}
|
||||
return $contents_same;
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue