FileList(3) User Contributed Perl Documentation FileList(3)NAMEFile::RsyncP::FileList - Perl interface to rsync file list encoding and
decoding.
SYNOPSIS
use File::RsyncP::FileList;
$fileList = File::RsyncP::FileList->new({
preserve_uid => 1,
preserve_gid => 1,
preserve_links => 1,
preserve_devices => 1,
preserve_hard_links => 0,
always_checksum => 0,
remote_version => 26,
});
# decoding an incoming file list
while ( !$fileList->decodeDone && !$fileList->fatalError ) {
$data .= readMoreDataFromRemoteRsync();
$bytesDone = $fileList->decode($data);
$data = substr($data, $bytesDone) if ( $bytesDone > 0 );
}
$fileList->clean;
# create (encode) a file list
$fileList->encode({
name => $filePath,
dev => $stat[0],
inode => $stat[1],
mode => $stat[2],
uid => $stat[4],
gid => $stat[5],
rdev => $stat[6],
mtime => $stat[9],
});
$data = $fileList->encodeData;
# get file information, for file number 5:
$fileInfo = $fileList->get(5);
# utility functions
$numberOfFiles = $fileList->count;
$gotFatalError = $fileList->fatalError;
DESCRIPTION
The File::RsyncP::FileList module is used to encode and decode file
lists in using the same format at Rsync.
The sender side of Rsync creates a list of all the files the are going
to be sent. This list is sent in a compact format to the receiver
side. Each side then sorts the list and removes duplicate entries.
From this point on, all files are referred to by their integer index
into the sorted file list.
A new file list object is created by calling
File::RsyncP::FileList->new. An object can be used to decode or encode
a file list. There is no mechanism to reset the state of a file list:
you should create a new object each time you need to do a new decode or
encode.
The new() function takes a hashref of options, which correspond to
various rsync command-line switches. These must exactly match the
arguments to the remote rsync, otherwise the file list format will not
be compatible and decoding will fail.
$fileList = File::RsyncP::FileList->new({
preserve_uid => 1, # --owner
preserve_gid => 1, # --group
preserve_links => 1, # --links
preserve_devices => 1, # --devices
preserve_hard_links => 0, # --hard-links
always_checksum => 0, # --checksum
remote_version => 26, # remote protocol version
});
Decoding
The decoding functions take a stream of bytes from the remote rsync and
convert them into an internal data structure. Rather than store the
file list as a native perl list of hashes (which occupies too much
memory for large file lists), the same internal data structure as rsync
is used. Individual file list entries can be returned with the get()
function.
File list data read from the remote rsync should be passed to the
decode() function. The data may be read and processed in arbitrary
sized chunks. The decode() function returns how many bytes were
actually processed. It is the caller's responsbility to remove that
number of bytes from the input argument, preserving the remaining bytes
for the next call to decode(). The decodeDone() function returns true
when the file list is complete. The fatalError() function returns true
if there was a non-recoverable error while decoding.
The clean() function needs to be called after the file list decode is
complete. The clean() function sorts the file list and removes
repeated entries. Skipping this step will produce unexpected results:
since files are referred to using integers, each side will refer to
different files is the file lists are not sorted and purged in exactly
the same manner.
A typical decode loop looks like:
while ( !$fileList->decodeDone && !$fileList->fatalError ) {
$data .= readMoreDataFromRemoteRsync();
$bytesDone = $fileList->decode($data);
$data = substr($data, $bytesDone) if ( $bytesDone > 0 );
}
$fileList->clean;
After clean() is called, the number of files in the file list can be
found by calling count(). Files can be fetched by calling the get()
function, with an index from 0 to count()-1:
$fileInfo = $fileList->get(5);
The get() function returns a hashref with various entries:
name path name of the file (relative to rsync dir):
equal to dirname/basename
basename file name, without directory
dirname directory where file resides
sum file MD4 checksum (only present if --checksum specified)
uid file user id
gid file group id
mode file mode
mtime file modification time
size file length
dev device number on which file resides
inode file inode
link link contents if the file is a sym link
rdev major/minor device number if file is char/block special
Various fields will only have valid values if the corresponding options
are set (eg: uid if preserve_uid is set, dev and inode if
preserve_hard_links is set etc).
For example, to dump out each of hash you could do this:
use Data::Dumper;
my $count = $fileList->count;
for ( my $i = 0 ; $i < $count ; $i++ ) {
print("File $i is:\n");
print Dumper($fileList->get($i));
}
Encoding
The encode() function is used to build a file list in preparation for
encoding and sending a file list to a remote rsync. The encode()
function takes a hashref argument with the parameters for one file. It
should be called once for each file. The parameter names are the same
as those returned by get().
In this example the matching stat() values are shown:
$fileList->encode({
name => $filePath,
dev => $stat[0],
inode => $stat[1],
mode => $stat[2],
uid => $stat[4],
gid => $stat[5],
rdev => $stat[6],
size => $stat[7],
mtime => $stat[9],
});
It is not necessary to specify basename and dirname; these are
extracted from name. You only need to specify the parameters that
match the options given to new(). You can also specify sum and link as
necessary.
To compute the encoded file list data the encodeData() function should
be called. It can be called every time encode() is called, or once at
the end of all the encode() calls. It returns the encoded data that
should be sent to the remote rsync:
$data = $fileList->encodeData;
It is recommended that encodeData() be called frequently to avoid the
need to allocate large internal buffers to hold the entire encoded file
list. Since encodeData() does not know when the last file has been
encoded, it is the caller's responsbility to add the final null byte
(eg: pack("C", 0)) to the data to indicate the end of the file list
data.
After all the file list entries are processed you should call clean():
$fileList->clean;
This ensures that each side (sender/receiver) has identical sorted file
lists.
Utility functions
The count() function returns the total number of files in the internal
file list (either decoded or encoded).
The fatalError() function returns true if a fatal error has occured
during file decoding. It should be called in the decode loop to make
sure no error has occured.
AUTHORFile::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 and File::RsyncP::FileIO for more precise examples of
using File::RsyncP::FileList.
Also see BackupPC's lib/BackupPC/Xfer/RsyncFileIO.pm for other
examples.
perl v5.18.2 2010-07-25 FileList(3)
