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#============================================================= -*-perl-*- |
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# |
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# BackupPC::Xfer::RsyncDigest package |
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# |
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# DESCRIPTION |
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# |
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# This library defines a BackupPC::Xfer::RsyncDigest class for computing |
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# and caching rsync checksums. |
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# |
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# AUTHOR |
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# Craig Barratt <cbarratt@users.sourceforge.net> |
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# |
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# COPYRIGHT |
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# Copyright (C) 2001-2003 Craig Barratt |
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# |
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# This program is free software; you can redistribute it and/or modify |
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# it under the terms of the GNU General Public License as published by |
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# the Free Software Foundation; either version 2 of the License, or |
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# (at your option) any later version. |
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# |
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# This program is distributed in the hope that it will be useful, |
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# but WITHOUT ANY WARRANTY; without even the implied warranty of |
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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# GNU General Public License for more details. |
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# |
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# You should have received a copy of the GNU General Public License |
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# along with this program; if not, write to the Free Software |
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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# |
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#======================================================================== |
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# |
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# Version 2.1.0, released 20 Jun 2004. |
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# |
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# See http://backuppc.sourceforge.net. |
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# |
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#======================================================================== |
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|
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package BackupPC::Xfer::RsyncDigest; |
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|
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use strict; |
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use BackupPC::FileZIO; |
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|
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use vars qw( $RsyncLibOK ); |
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use Carp; |
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require Exporter; |
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use vars qw( @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS ); |
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|
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my $Log = \&logHandler; |
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|
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# |
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# Magic value for checksum seed. We only cache block and file digests |
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# when the checksum seed matches this value. |
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# |
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use constant RSYNC_CSUMSEED_CACHE => 32761; |
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|
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@ISA = qw(Exporter); |
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|
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@EXPORT = qw( ); |
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|
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@EXPORT_OK = qw( |
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RSYNC_CSUMSEED_CACHE |
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); |
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|
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%EXPORT_TAGS = ( |
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'all' => [ @EXPORT_OK ], |
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); |
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|
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BEGIN { |
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eval "use File::RsyncP;"; |
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if ( $@ ) { |
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# |
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# File::RsyncP doesn't exist. Define some dummy constant |
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# subs so that the code below doesn't barf. |
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# |
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$RsyncLibOK = 0; |
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} else { |
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$RsyncLibOK = 1; |
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} |
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}; |
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|
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# |
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# Return the rsync block size based on the file size. |
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# We also make sure the block size plus 4 (ie: cheeksumSeed) |
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# is not a multiple of 64 - otherwise the cached checksums |
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# will not be the same for protocol versions <= 26 and > 26. |
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# |
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sub blockSize |
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{ |
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my($class, $fileSize, $defaultBlkSize) = @_; |
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|
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my $blkSize = int($fileSize / 10000); |
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$blkSize = $defaultBlkSize if ( $blkSize < $defaultBlkSize ); |
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$blkSize = 16384 if ( $blkSize > 16384 ); |
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$blkSize += 4 if ( (($blkSize + 4) % 64) == 0 ); |
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return $blkSize; |
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} |
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|
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sub fileDigestIsCached |
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{ |
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my($class, $file) = @_; |
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my $data; |
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|
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open(my $fh, "<", $file) || return -1; |
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binmode($fh); |
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return -2 if ( sysread($fh, $data, 1) != 1 ); |
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close($fh); |
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return $data eq chr(0xd6) ? 1 : 0; |
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} |
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|
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# |
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# Compute and add rsync block and file digests to the given file. |
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# |
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# Empty files don't get cached checksums. |
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# |
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# If verify is set then existing cached checksums are checked. |
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# |
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# Returns 0 on success. Returns 1 on good verify and 2 on bad verify. |
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# Returns a variety of negative values on error. |
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# |
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sub digestAdd |
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{ |
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my($class, $file, $blockSize, $checksumSeed, $verify) = @_; |
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my $retValue = 0; |
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|
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# |
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# Don't cache checksums if the checksumSeed is not RSYNC_CSUMSEED_CACHE |
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# or if the file is empty. |
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# |
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return -100 if ( $checksumSeed != RSYNC_CSUMSEED_CACHE || !-s $file ); |
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|
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if ( $blockSize == 0 ) { |
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&$Log("digestAdd: bad blockSize ($file, $blockSize, $checksumSeed)"); |
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$blockSize = 2048; |
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} |
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my $nBlks = int(65536 * 16 / $blockSize) + 1; |
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my($data, $blockDigest, $fileDigest); |
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|
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return -101 if ( !$RsyncLibOK ); |
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|
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my $digest = File::RsyncP::Digest->new; |
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$digest->add(pack("V", $checksumSeed)) if ( $checksumSeed ); |
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|
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return -102 if ( !defined(my $fh = BackupPC::FileZIO->open($file, 0, 1)) ); |
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|
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while ( 1 ) { |
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$fh->read(\$data, $nBlks * $blockSize); |
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last if ( $data eq "" ); |
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$blockDigest .= $digest->blockDigest($data, $blockSize, 16, |
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$checksumSeed); |
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$digest->add($data); |
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} |
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$fileDigest = $digest->digest2; |
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my $eofPosn = sysseek($fh->{fh}, 0, 1); |
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$fh->close; |
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my $rsyncData = $blockDigest . $fileDigest; |
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my $metaData = pack("VVVV", $blockSize, |
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$checksumSeed, |
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length($blockDigest) / 20, |
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0x5fe3c289, # magic number |
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); |
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my $data2 = chr(0xb3) . $rsyncData . $metaData; |
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# printf("appending %d+%d bytes to %s at offset %d\n", |
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# length($rsyncData), |
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# length($metaData), |
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# $file, |
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# $eofPosn); |
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open(my $fh2, "+<", $file) || return -103; |
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binmode($fh2); |
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return -104 if ( sysread($fh2, $data, 1) != 1 ); |
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if ( $data ne chr(0x78) && $data ne chr(0xd6) ) { |
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&$Log(sprintf("digestAdd: $file has unexpected first char 0x%x", |
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ord($data))); |
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return -105; |
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} |
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return -106 if ( sysseek($fh2, $eofPosn, 0) != $eofPosn ); |
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if ( $verify ) { |
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my $data3; |
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|
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# |
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# Verify the cached checksums |
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# |
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return -107 if ( $data ne chr(0xd6) ); |
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return -108 if ( sysread($fh2, $data3, length($data2) + 1) < 0 ); |
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if ( $data2 eq $data3 ) { |
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return 1; |
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} |
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# |
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# Checksums don't agree - fall through so we rewrite the data |
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# |
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&$Log("digestAdd: $file verify failed; redoing checksums"); |
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return -109 if ( sysseek($fh2, $eofPosn, 0) != $eofPosn ); |
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$retValue = 2; |
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} |
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return -110 if ( syswrite($fh2, $data2) != length($data2) ); |
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if ( $verify ) { |
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# |
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# Make sure there is no extraneous data on the end of |
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# the file. Seek to the end and truncate if it doesn't |
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# match our expected length. |
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# |
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return -111 if ( !defined(sysseek($fh2, 0, 2)) ); |
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if ( sysseek($fh2, 0, 1) != $eofPosn + length($data2) ) { |
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if ( !truncate($fh2, $eofPosn + length($data2)) ) { |
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&$Log(sprintf("digestAdd: $file truncate from %d to %d failed", |
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sysseek($fh2, 0, 1), $eofPosn + length($data2))); |
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return -112; |
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} else { |
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&$Log(sprintf("digestAdd: $file truncated from %d to %d", |
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sysseek($fh2, 0, 1), $eofPosn + length($data2))); |
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} |
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} |
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} |
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return -113 if ( !defined(sysseek($fh2, 0, 0)) ); |
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return -114 if ( syswrite($fh2, chr(0xd6)) != 1 ); |
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close($fh2); |
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return $retValue; |
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} |
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|
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# |
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# Return rsync checksums for the given file. We read the cached checksums |
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# if they exist and the block size and checksum seed match. Otherwise |
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# we compute the checksums from the file contents. |
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# |
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# The doCache flag can take three ranges: |
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# |
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# - doCache < 0: don't generate/use cached checksums |
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# - doCache == 0: don't generate, but do use cached checksums if available |
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# - doCache > 0: generate (if necessary) and use cached checksums |
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# |
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# Note: caching is only enabled when compression is on and the |
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# checksum seed is RSYNC_CSUMSEED_CACHE (32761). |
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# |
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# Returns 0 on success. Returns a variety of negative values on error. |
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# |
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sub digestStart |
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{ |
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my($class, $fileName, $fileSize, $blockSize, $defBlkSize, |
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$checksumSeed, $needMD4, $compress, $doCache) = @_; |
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|
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return -1 if ( !$RsyncLibOK ); |
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|
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my $data; |
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|
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my $dg = bless { |
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name => $fileName, |
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needMD4 => $needMD4, |
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digest => File::RsyncP::Digest->new, |
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}, $class; |
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|
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if ( $fileSize > 0 && $compress && $doCache >= 0 ) { |
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open(my $fh, "<", $fileName) || return -2; |
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binmode($fh); |
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return -3 if ( read($fh, $data, 1) != 1 ); |
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my $ret; |
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|
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if ( $data eq chr(0x78) && $doCache > 0 |
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&& $checksumSeed == RSYNC_CSUMSEED_CACHE ) { |
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# |
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# RSYNC_CSUMSEED_CACHE (32761) is the magic number that |
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# rsync uses for checksumSeed with the --fixed-csum option. |
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# |
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# We now add the cached checksum data to the file. There |
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# is a possible race condition here since two BackupPC_dump |
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# processes might call this function at the same time |
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# on the same file. But this should be ok since both |
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# processes will write the same data, and the order |
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# in which they write it doesn't matter. |
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# |
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close($fh); |
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$ret = $dg->digestAdd($fileName, |
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$blockSize |
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|| BackupPC::Xfer::RsyncDigest->blockSize( |
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$fileSize, $defBlkSize), |
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$checksumSeed); |
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if ( $ret < 0 ) { |
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&$Log("digestAdd($fileName) failed ($ret)"); |
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} |
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# |
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# now re-open the file and re-read the first byte |
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# |
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open($fh, "<", $fileName) || return -4; |
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binmode($fh); |
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return -5 if ( read($fh, $data, 1) != 1 ); |
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} |
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if ( $ret >= 0 && $data eq chr(0xd6) ) { |
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# |
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# Looks like this file has cached checksums |
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# Read the last 48 bytes: that's 2 file MD4s (32 bytes) |
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# plus 4 words of meta data |
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# |
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return -6 if ( !defined(seek($fh, -48, 2)) ); |
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return -7 if ( read($fh, $data, 48) != 48 ); |
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($dg->{md4DigestOld}, |
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$dg->{md4Digest}, |
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$dg->{blockSize}, |
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$dg->{checksumSeed}, |
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$dg->{nBlocks}, |
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$dg->{magic}) = unpack("a16 a16 V V V V", $data); |
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if ( $dg->{magic} == 0x5fe3c289 |
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&& $dg->{checksumSeed} == $checksumSeed |
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&& ($blockSize == 0 || $dg->{blockSize} == $blockSize) ) { |
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$dg->{fh} = $fh; |
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$dg->{cached} = 1; |
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# |
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# position the file at the start of the rsync block checksums |
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# (4 (adler) + 16 (md4) bytes each) |
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# |
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return -8 |
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if ( !defined(seek($fh, -$dg->{nBlocks}*20 - 48, 2)) ); |
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} else { |
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# |
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# cached checksums are not valid, so we close the |
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# file and treat it as uncached. |
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# |
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$dg->{cachedInvalid} = 1; |
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close($fh); |
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} |
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} |
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} |
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if ( !$dg->{cached} ) { |
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# |
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# This file doesn't have cached checksums, or the checksumSeed |
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# or blocksize doesn't match. Open the file and prepare to |
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# compute the checksums. |
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# |
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$blockSize |
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= BackupPC::Xfer::RsyncDigest->blockSize($fileSize, $defBlkSize) |
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if ( $blockSize == 0 ); |
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$dg->{checksumSeed} = $checksumSeed; |
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$dg->{blockSize} = $blockSize; |
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$dg->{fh} = BackupPC::FileZIO->open($fileName, 0, $compress); |
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return -9 if ( !defined($dg->{fh}) ); |
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if ( $needMD4) { |
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$dg->{csumDigest} = File::RsyncP::Digest->new; |
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$dg->{csumDigest}->add(pack("V", $dg->{checksumSeed})); |
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} |
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} |
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return (undef, $dg, $dg->{blockSize}); |
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} |
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|
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sub digestGet |
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{ |
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my($dg, $num, $csumLen, $noPad) = @_; |
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my($fileData); |
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my $blockSize = $dg->{blockSize}; |
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|
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if ( $dg->{cached} ) { |
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my $thisNum = $num; |
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$thisNum = $dg->{nBlocks} if ( $thisNum > $dg->{nBlocks} ); |
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read($dg->{fh}, $fileData, 20 * $thisNum); |
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$dg->{nBlocks} -= $thisNum; |
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if ( $thisNum < $num && !$noPad) { |
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# |
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# unexpected shortfall of data; pad with zero digest |
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# |
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$fileData .= pack("c", 0) x (20 * ($num - $thisNum)); |
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} |
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return $dg->{digest}->blockDigestExtract($fileData, $csumLen); |
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} else { |
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if ( $dg->{fh}->read(\$fileData, $blockSize * $num) <= 0 ) { |
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# |
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# unexpected shortfall of data; pad with zeros |
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# |
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$fileData = pack("c", 0) x ($blockSize * $num) if ( !$noPad ); |
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} |
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$dg->{csumDigest}->add($fileData) if ( $dg->{needMD4} ); |
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return $dg->{digest}->blockDigest($fileData, $blockSize, |
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$csumLen, $dg->{checksumSeed}); |
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} |
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} |
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|
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sub digestEnd |
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{ |
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my($dg, $skipMD4) = @_; |
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my($fileData); |
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|
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if ( $dg->{cached} ) { |
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close($dg->{fh}); |
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return $dg->{md4DigestOld} if ( $dg->{needMD4} ); |
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} else { |
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# |
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# make sure we read the entire file for the file MD4 digest |
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# |
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if ( $dg->{needMD4} && !$skipMD4 ) { |
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my $fileData; |
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while ( $dg->{fh}->read(\$fileData, 65536) > 0 ) { |
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$dg->{csumDigest}->add($fileData); |
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} |
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} |
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$dg->{fh}->close(); |
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return $dg->{csumDigest}->digest if ( $dg->{needMD4} ); |
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} |
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} |
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|
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sub isCached |
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{ |
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my($dg) = @_; |
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|
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return wantarray ? ($dg->{cached}, $dg->{cachedInvalid}) : $dg->{cached}; |
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} |
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|
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sub blockSizeCurr |
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{ |
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my($dg) = @_; |
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|
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return $dg->{blockSize}; |
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} |
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|
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# |
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# Default log handler |
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# |
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sub logHandler |
| 413 |
{ |
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my($str) = @_; |
| 415 |
|
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print(STDERR $str, "\n"); |
| 417 |
} |
| 418 |
|
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# |
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# Set log handler to a new subroutine. |
| 421 |
# |
| 422 |
sub logHandlerSet |
| 423 |
{ |
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my($sub) = @_; |
| 425 |
|
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$Log = $sub; |
| 427 |
} |
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|
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1; |
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