NAME

       File::RsyncP::FileIO - Perl Rsync client file system IO

SYNOPSIS

           use File::RsyncP::FileIO;

           my $rs = File::RsyncP->new({
                       logLevel   => 1,
                       rsyncCmd => ["/bin/rsh", $host,  "-l", $user, "/bin/rsync"],
                       rsyncArgs  => [qw(
                               --numeric-ids
                               --perms
                               --owner
                               --group
                               --devices
                               --links
                               --ignore-times
                               --block-size=700
                               --relative
                               --recursive
                               -v
                           )],
                       logHandler => sub {
                               my($str) = @_;
                               print MyHandler "log: $str\n";
                           };
                       fio        => File::RsyncP::FileIO->new({
                                       logLevel   => 1,
                                   });

                   });

DESCRIPTION

       File::RsyncP::FileIO contains all of the file system access functions needed by File::RsyncP.  This
       functionality is relegated to this module so it can be subclassed or replaced by different code for
       applications where an rsync interface is provided for non-file system data (eg: databases).

       File::RsyncP::FileIO provides the following functions.

   Setup and utility functions
       new({ options... })
           Creates a new File::RsyncP::FileIO object.  The single argument is a hashref of options:

           blockSize
               Defaults to 700.  Can be set later using the blockSize function.

           logLevel
               Defaults to 0.  Controls the verbosity of FileIO operations.

           digest
               Defaults to File::RsyncP::Digest->new.  No need to override.

           checksumSeed
               The checksum seed used in digest calculations.  Defaults to 0.  The server-side Rsync generates a
               checksum seed and sends it to the client.  This value is usually set later, after the checksum
               seed is received from the remote rsync, via the checksumSeed function.

           logHandler
               A subroutine reference to a function that handles all the log messages.  The default is a
               subroutine that prints the messages to STDERR.

       blockSize($value)
           Set the block size to the new value, in case it wasn't set via the blockSize option to new().

       checksumSeed($seed)
           Set the checksum seed used in digest calculations to the new value.  Usually this value isn't known
           when new() is called, so it is necessary to set it later via this function.

       logHandlerSet
           Set the log handler callback function.  Usually this value is specified via new(), but it can be
           changed later via this function.

       dirs($localDir, $remoteDir)
           Specify the local and remote directories.

       log(@msg)
           Save one (or more) messages for logging purposes.

       statsGet
           Return an optional hashref of statistics compiled by the FileIO object.  These values are opaquely
           passed up to File::RsyncP.

       finish($isChild)
           Do any necessary finish-up processing.  The $isChild argument is true if this is the child process
           (remember the receiving side has two processes: the child receives the file deltas while the parent
           generates the block digests).

   Checksum computation functions
       csumStart($f, $needMD4)
           Get ready to generate block checksums for the given file.  The argument is a hashref typically
           returned by File::RsyncP::FileList->get.  Typically this opens the underlying file and creates a
           File::RsyncP::Digest object.  If $needMD4 is non-zero, then csumEnd() will return the file MD4
           digest.

       csumGet($num, $csumLen, $blockSize)
           Return $num bkocks work of checksums with the MD4 checksum length of $csumLen (typically 2 or 16),
           with a block size of $blockSize.  Typically this reads the file and calls
           File::RsyncP::Digest->blockDigest.

       csumEnd()
           Finish up the checksum calculation.  Typically closes the underlying file.  Note that csumStart,
           csumGet, csumEnd are called in strict order so they don't need to be reentrant (ie: there is only one
           csum done at a time).  If csumStart() was called with $needMD4 then csumEnd() will return the file
           MD4 digest.

   File reading functions
       There are used for sending files (currently sending files doesn't implement deltas; it behaves as though
       --whole-file was specified):

       readStart($f)
           Get ready to read the given file.  The argument is a hashref typically returned by
           File::RsyncP::FileList->get.  Typically this opens the underlying file.

       read($num)
           Read $num bytes from the file.

       readEnd()
           Finish up the read operation.  Typically closes the underlying file.  Note that readStart, readGet,
           readEnd are called in strict order so they don't need to be reentrant (ie: there is only one read
           done at a time).

   File operations
       attribGet($f)
           Return the attributes for the given file as a hashref.  The argument is a hashref typically returned
           by File::RsyncP::FileList->get.

       attribSet($f, $placeHolder)
           Set the attributes for the given file.  The argument is a hashref typically returned by
           File::RsyncP::FileList->get.  If $placeHolder is true then don't do anything.  Returns undef on
           success.

       makePath($f)
           Create the directory specified by $f.  The argument is a hashref typically returned by
           File::RsyncP::FileList->get.  Returns undef on success.

       makeSpecial($f)
           Create the special file specified by $f.  The argument is a hashref typically returned by
           File::RsyncP::FileList->get.  Returns undef on success.

       unlink($remotePath)
           Unlink the file or directory corresponding to the given remote path.

       ignoreAttrOnFile($f)
           Normally should return undef, meaning use the default setting of ignore-times.  Otherwise, if this
           function returns zero or non-zero, the returned value  overrides the setting of ignore-times for this
           file.  The argument is a hashref typically returned by File::RsyncP::FileList->get.  See the
           doPartial option in File::RsyncP->new().

   File delta receiving functions
       These functions are only called when we are receiving files.  They are called by the child process.

       fileDeltaRxStart($f, $cnt, $size, $remainder)
           Start the receiving of file deltas for file $f, a hashref typically returned by
           File::RsyncP::FileList->get.  The remaining arguments are the number of blocks, size of blocks, and
           size of the last (partial) block as generated by the parent on the receiving side (they are not the
           values the new file on the sending side).  Returns undef on success.

       fileDeltaRxNext($blk, $newData)
           This function is called repeatedly as the file is constructed.  Exactly one of $blk and $newData are
           defined.  If $blk is defined it is an integer that specifies which block of the original file should
           be written at this point.  If $newData is defined, it is literal data (that didn't match any blocks)
           that should be written at this point.

       fileDeltaRxDone($md4)
           Finish processing of the file deltas for this file.  $md4 is the MD4 digest of the sent file.  It
           should be compared against the MD4 digest of the reconstructed file.  Returns undef on success, 1 if
           the file's MD4 didn't agree (meaning it should be repeated for phase 2), and negative on error.

   File list sending function
       fileListSend($fileList, $outputFunc)
           Generate the file list (by calling $fileList->encode for every file to be sent) and call the output
           function $outputFunc with the output data by calling

               &$outputFunc($fileList->encodeData);

AUTHOR

       File::RsyncP::FileList was written by Craig Barratt <cbarratt@users.sourceforge.net> based on rsync
       2.5.5.

       Rsync was written by Andrew Tridgell <tridge@samba.org> and Paul Mackerras.  It is available under a GPL
       license.  See http://rsync.samba.org

LICENSE

       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 in the LICENSE file along with this
       program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
       02111-1307 USA.

SEE ALSO

       See <http://perlrsync.sourceforge.net> for File::RsyncP's SourceForge home page.

       See File::RsyncP, File::RsyncP::Digest, and File::RsyncP::FileList.

       Also see BackupPC's lib/BackupPC/Xfer/RsyncFileIO.pm for an example of another implementation of
       File::RsyncP::FileIO, in fact one that is more tested than the default File::RsyncP::FileIO.pm.