#============================================================= -*-perl-*- # # BackupPC::Xfer::RsyncDigest package # # DESCRIPTION # # This library defines a BackupPC::Xfer::RsyncDigest class for computing # and caching rsync checksums. # # AUTHOR # Craig Barratt # # COPYRIGHT # Copyright (C) 2001-2003 Craig Barratt # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program; if not, write to the Free Software # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA # #======================================================================== # # Version 2.1.0_CVS, released 3 Jul 2003. # # See http://backuppc.sourceforge.net. # #======================================================================== package BackupPC::Xfer::RsyncDigest; use strict; use vars qw( $RsyncLibOK ); use Carp; BEGIN { eval "use File::RsyncP;"; if ( $@ ) { # # File::RsyncP doesn't exist. Define some dummy constant # subs so that the code below doesn't barf. # $RsyncLibOK = 0; } else { $RsyncLibOK = 1; } }; # # Return the rsync block size based on the file size. # We also make sure the block size plus 4 (ie: cheeksumSeed) # is not a multiple of 64 - otherwise the cached checksums # will not be the same for protocol versions <= 26 and > 26. # sub blockSize { my($class, $fileSize, $defaultBlkSize) = @_; my $blkSize = int($fileSize / 10000); $blkSize = $defaultBlkSize if ( $blkSize < $defaultBlkSize ); $blkSize = 16384 if ( $blkSize > 16384 ); $blkSize += 4 if ( (($blkSize + 4) % 64) == 0 ); return $blkSize; } # # Compute and add rsync block and file digests to the given file. # sub digestAdd { my($class, $file, $blockSize, $checksumSeed) = @_; if ( $blockSize == 0 ) { print("bogus digestAdd($file, $blockSize, $checksumSeed)\n"); $blockSize = 2048; } my $nBlks = int(65536 * 16 / $blockSize) + 1; my($data, $blockDigest, $fileDigest); return if ( !$RsyncLibOK ); my $digest = File::RsyncP::Digest->new; $digest->add(pack("V", $checksumSeed)) if ( $checksumSeed ); return -1 if ( !defined(my $fh = BackupPC::FileZIO->open($file, 0, 1)) ); while ( 1 ) { $fh->read(\$data, $nBlks * $blockSize); last if ( $data eq "" ); $blockDigest .= $digest->blockDigest($data, $blockSize, 16, $checksumSeed); $digest->add($data); } $fileDigest = $digest->digest2; my $eofPosn = tell($fh->{fh}); $fh->close; my $rsyncData = $blockDigest . $fileDigest; my $metaData = pack("VVVV", $blockSize, $checksumSeed, length($blockDigest) / 20, 0x5fe3c289, # magic number ); my $data2 = chr(0xb3) . $rsyncData . $metaData; # printf("appending %d+%d bytes to %s at offset %d\n", # length($rsyncData), # length($metaData), # $file, # $eofPosn); open(my $fh2, "+<", $file) || return -2; binmode($fh2); return -3 if ( sysread($fh2, $data, 1) != 1 ); if ( $data ne chr(0x78) && $data ne chr(0xd6) ) { printf("Unexpected first char 0x%x\n", ord($data)); return -4; } return -5 if ( sysseek($fh2, $eofPosn, 0) != $eofPosn ); return -6 if ( syswrite($fh2, $data2) != length($data2) ); return -7 if ( !defined(sysseek($fh2, 0, 0)) ); return -8 if ( syswrite($fh2, chr(0xd6)) != 1 ); close($fh2); } # # Return rsync checksums for the given file. We read the cached checksums # if they exist and the block size and checksum seed match. Otherwise # we compute the checksums from the file contents. # sub digestStart { my($class, $fileName, $fileSize, $blockSize, $defBlkSize, $checksumSeed, $needMD4, $compress, $doCache) = @_; return -1 if ( !$RsyncLibOK ); my $data; my $fio = bless { name => $fileName, needMD4 => $needMD4, digest => File::RsyncP::Digest->new, }, $class; if ( $fileSize > 0 && $compress ) { open(my $fh, "<", $fileName) || return -2; binmode($fh); return -3 if ( read($fh, $data, 1) != 1 ); if ( $data eq chr(0x78) && $doCache && $checksumSeed == 32761 ) { # # 32761 is the magic number that rsync uses for checksumSeed # with the --fixed-csum option. # # We now add the cached checksum data to the file. There # is a possible race condition here since two BackupPC_dump # processes might call this function at the same time # on the same file. But this should be ok since both # processes will write the same data, and the order # in which they write it doesn't matter. # close($fh); $fio->digestAdd($fileName, $blockSize || BackupPC::Xfer::RsyncDigest->blockSize($fileSize, $defBlkSize), $checksumSeed); # # now re-open the file and re-read the first byte # open($fh, "<", $fileName) || return -2; binmode($fh); return -3 if ( read($fh, $data, 1) != 1 ); } if ( $data eq chr(0xd6) ) { # # Looks like this file has cached checksums # Read the last 48 bytes: that's 2 file MD4s (32 bytes) # plus 4 words of meta data # return -4 if ( !defined(seek($fh, -48, 2)) ); return -5 if ( read($fh, $data, 48) != 48 ); ($fio->{md4DigestOld}, $fio->{md4Digest}, $fio->{blockSize}, $fio->{checksumSeed}, $fio->{nBlocks}, $fio->{magic}) = unpack("a16 a16 V V V V", $data); if ( $fio->{magic} == 0x5fe3c289 && $fio->{checksumSeed} == $checksumSeed && ($blockSize == 0 || $fio->{blockSize} == $blockSize) ) { $fio->{fh} = $fh; $fio->{cached} = 1; } else { close($fh); } # # position the file at the start of the rsync block checksums # (4 (adler) + 16 (md4) bytes each) # return -6 if ( !defined(seek($fh, -$fio->{nBlocks}*20 - 48, 2)) ); } } if ( !$fio->{cached} ) { # # This file doesn't have cached checksums, or the checksumSeed # or blocksize doesn't match. Open the file and prepare to # compute the checksums. # $blockSize = BackupPC::Xfer::RsyncDigest->blockSize($fileSize, $defBlkSize) if ( $blockSize == 0 ); $fio->{checksumSeed} = $checksumSeed; $fio->{blockSize} = $blockSize; $fio->{fh} = BackupPC::FileZIO->open($fileName, 0, $compress); return -7 if ( !defined($fio->{fh}) ); if ( $needMD4) { $fio->{csumDigest} = File::RsyncP::Digest->new; $fio->{csumDigest}->add(pack("V", $fio->{checksumSeed})); } } return (undef, $fio, $fio->{blockSize}); } sub digestGet { my($fio, $num, $csumLen) = @_; my($fileData); my $blockSize = $fio->{blockSize}; if ( $fio->{cached} ) { my $thisNum = $num; $thisNum = $fio->{nBlocks} if ( $thisNum > $fio->{nBlocks} ); read($fio->{fh}, $fileData, 20 * $thisNum); $fio->{nBlocks} -= $thisNum; if ( $thisNum < $num ) { # # unexpected shortfall of data; pad with zero digest # $fileData .= pack("c", 0) x (20 * ($num - $thisNum)); } return $fio->{digest}->blockDigestExtract($fileData, $csumLen); } else { if ( $fio->{fh}->read(\$fileData, $blockSize * $num) <= 0 ) { # # unexpected shortfall of data; pad with zeros # $fileData = pack("c", 0) x ($blockSize * $num); } $fio->{csumDigest}->add($fileData) if ( $fio->{needMD4} ); return $fio->{digest}->blockDigest($fileData, $blockSize, $csumLen, $fio->{checksumSeed}); } } sub digestEnd { my($fio) = @_; my($fileData); if ( $fio->{cached} ) { close($fio->{fh}); return $fio->{md4DigestOld} if ( $fio->{needMD4} ); } else { # # make sure we read the entire file for the file MD4 digest # if ( $fio->{needMD4} ) { my $fileData; while ( $fio->{fh}->read(\$fileData, 65536) > 0 ) { $fio->{csumDigest}->add($fileData); } } $fio->{fh}->close(); return $fio->{csumDigest}->digest if ( $fio->{needMD4} ); } } 1;