File-Rdiff/Rdiff.pm

=head1 NAME

File::Rdiff -- generate remote signatures and patch files using librsync

=head1 SYNOPSIS

 use File::Rdiff

=head1 DESCRIPTION

A more-or-less direct interface to librsync (L<http://rproxy.samba.org>).

For usage examples (better than this very sparse documentation), see the
two example scripts rdiff1 and rdiff2 that came with the distribution.

=over 4

=cut

package File::Rdiff;

require DynaLoader;
require Exporter;

$VERSION = 0.01;
@ISA = qw/DynaLoader Exporter/;

bootstrap File::Rdiff $VERSION;

{
   my @loglevels = qw(LOG_EMERG LOG_ALERT LOG_CRIT LOG_ERR LOG_WARNING LOG_NOTICE LOG_INFO LOG_DEBUG);
   my @result = qw(DONE BLOCKED RUNNING TEST_SKIPPED IO_ERROR SYNTAX_ERROR MEM_ERROR INPUT_ENDED BAD_MAGIC UNIMPLEMENTED CORRUPT INTERNAL_ERROR PARAM_ERROR);

   %EXPORT_TAGS = (
           loglevels   => [@loglevels],
           trace       => [@loglevels, qw(trace_level trace_to)],
           result      => [@result],
           error       => [@result, qw(strerror)],
           file        => [@result, qw(md4_file sig_file loadsig_file delta_file patch_file)],
           nonblocking => [@result],
   );

   my %export_ok;
   @export_ok{map @$_, values %EXPORT_TAGS} = ();
   @EXPORT_OK = keys %export_ok;
}

=item LIBRSYNC_VERSION

A constant describing the version of the rsync library used in this
module. My version claimed to be "0.9.5 librsync" when I wrote this
document ;)

=item $oldlevel = trace_level [$newlevel]

Return the current tracelevel and optionally set a new one.

=item $oldcb = trace_to [$newcb]

Return the current trace callback and optionally set a new one. The callback will be
called with the log level as the first argument and the log message as the second one.

Calling C<trace_to> with C<undef> will restore the default handler (which
currently prints the message to standard error).

=item supports_trace

Returns wether debugging traces are supported in this version of the library.

=item $msg = strerror $rcode

Returns a string representation of the given error code. You usually
just "exit(1)" or something when a function/method fails, as all (most?)
librsync functions log the error properly, so there is rarely a need to
call this function.

=item $md4 = md4_file $fh

=item sig_file $old_fh, $sig_fh[, $block_len[, $strong_len]]

=item $sig = loadsig_file $fh

=item delta_file $signature, $new_fh, $delta_fh

=item patch_file $base_fh, $delta_fh, $new_fh

=back

=head2 The File::Rdiff::Job class

=head2 The File::Rdiff::Buffers class

This class contains the input and output buffers for the non-blocking interface. It is slightly unusual
in that it allows direct manipulation of (some) of it's internal variables.

=over 4

=item new File::Rdiff::Buffers [$outsize]

Creates and initializes a new buffers structure. C<$outsize> specifies
the maximum number of bytes to be read into the output scalar until it is
considered full. The default is 64k.

=item $buffers->in($in)

Set the next block of input to consume. Data will be read from this scalar
(no copy will be made!) until all bytes have been consumed or a new input
scalar is set.

=item $out = $buffers->out

Return the current output data and create a new buffer. Returns C<undef> if no data has been accumulated.

=item $buffers->eof

Set the eof flag to true. This indicates that no data is following the current input scalar.

=item $buffers->avail_in

Returns the numer of bytes still available for input. If there are no
input bytes available but the eof flag is set, returns -1 (to make boolean
tests easy to check wether to supply more data easier).

=item $buffers->avail_out

Returns the number of bytes still available in the output buffer.

=item $buffers->size

The number of bytes that have been accumulated in the current buffer so far.

=back

=head2 The File::Rdiff::Job class

It is possible to have multiple jobs running at the same time. The idea
is to create job objects and then drive them incrementally with input or
output data until all date has been processed.

=over 4

=item new_sig File::Rdiff::Job [$new_block_len[, $strong_sum_len]]

Create a job that converts a base stream into a signature stream (i.e. creates signatures).

=item new_loadsig File::Rdiff::Job

Create a job that converts the input stream into a in-memory
File::Rdiff::Signature object. The signature object can be fetched anytime
with the C<signature>-method.

=item new_delta File::Rdiff::Job $signature

Creates a job that creates (outputs) a delta between the input stream (the
newer file) and the file represented by the given signature.

=item new_patch File::Rdiff::Job $callback_or_filehandle

Creates a job that patches a file according to the input stream (a delta
stream). The single argument is used to read the base file contents. If it
is a filehandle, it must be a seekable handle to the base file.

If it is a coderef, it will be called whenever base file data must be
read. Two arguments will be passed: the file offset and the length. The
callback should eithe return the data read (must be a string, not a
number!) or an error code.

=item $job->iter($buffers)

Do as much work as possible given the input and/or output data in the
File::Rdiff::Buffers structure and return either C<DONE> when the job is
finished, C<BLOCKED> if there aren't enough bytes available in the input
or output buffers (in which case you should deplete the output buffer
and/or fill the input buffer and loop), or some error code indicating that
the operation failed.

=item $job->signature

Only valid for C<new_loadsig>, so look there.

=back

=head1 SEE ALSO

L<File::Rsync>, L<rdiff1> (usage example using simple file API), L<rdiff2> (example using nonblocking API).

=head1 BUGS

- not well-tested so far.

- low memory will result in segfaults rather than croaks.

- no access to statistics yet

- documentation leaves much to be deserved.

=head1 AUTHOR

 Marc Lehmann <pcg@goof.com>
 http://home.schmorp.de/

=cut

1;

Revision:	1.4
Committed:	Wed Jan 12 20:35:42 2005 UTC (19 years, 4 months ago) by root
Branch:	MAIN
Changes since 1.3:	+1 -1 lines
Log Message:	* empty log message *
#	Content
1	=head1 NAME
2
3	File::Rdiff -- generate remote signatures and patch files using librsync
4
5	=head1 SYNOPSIS
6
7	use File::Rdiff
8
9	=head1 DESCRIPTION
10
11	A more-or-less direct interface to librsync (L<http://rproxy.samba.org>).
12
13	For usage examples (better than this very sparse documentation), see the
14	two example scripts rdiff1 and rdiff2 that came with the distribution.
15
16	=over 4
17
18	=cut
19
20	package File::Rdiff;
21
22	require DynaLoader;
23	require Exporter;
24
25	$VERSION = 0.01;
26	@ISA = qw/DynaLoader Exporter/;
27
28	bootstrap File::Rdiff $VERSION;
29
30	{
31	my @loglevels = qw(LOG_EMERG LOG_ALERT LOG_CRIT LOG_ERR LOG_WARNING LOG_NOTICE LOG_INFO LOG_DEBUG);
32	my @result = qw(DONE BLOCKED RUNNING TEST_SKIPPED IO_ERROR SYNTAX_ERROR MEM_ERROR INPUT_ENDED BAD_MAGIC UNIMPLEMENTED CORRUPT INTERNAL_ERROR PARAM_ERROR);
33
34	%EXPORT_TAGS = (
35	loglevels => [@loglevels],
36	trace => [@loglevels, qw(trace_level trace_to)],
37	result => [@result],
38	error => [@result, qw(strerror)],
39	file => [@result, qw(md4_file sig_file loadsig_file delta_file patch_file)],
40	nonblocking => [@result],
41	);
42
43	my %export_ok;
44	@export_ok{map @$_, values %EXPORT_TAGS} = ();
45	@EXPORT_OK = keys %export_ok;
46	}
47
48	=item LIBRSYNC_VERSION
49
50	A constant describing the version of the rsync library used in this
51	module. My version claimed to be "0.9.5 librsync" when I wrote this
52	document ;)
53
54	=item $oldlevel = trace_level [$newlevel]
55
56	Return the current tracelevel and optionally set a new one.
57
58	=item $oldcb = trace_to [$newcb]
59
60	Return the current trace callback and optionally set a new one. The callback will be
61	called with the log level as the first argument and the log message as the second one.
62
63	Calling C<trace_to> with C<undef> will restore the default handler (which
64	currently prints the message to standard error).
65
66	=item supports_trace
67
68	Returns wether debugging traces are supported in this version of the library.
69
70	=item $msg = strerror $rcode
71
72	Returns a string representation of the given error code. You usually
73	just "exit(1)" or something when a function/method fails, as all (most?)
74	librsync functions log the error properly, so there is rarely a need to
75	call this function.
76
77	=item $md4 = md4_file $fh
78
79	=item sig_file $old_fh, $sig_fh[, $block_len[, $strong_len]]
80
81	=item $sig = loadsig_file $fh
82
83	=item delta_file $signature, $new_fh, $delta_fh
84
85	=item patch_file $base_fh, $delta_fh, $new_fh
86
87	=back
88
89	=head2 The File::Rdiff::Job class
90
91	=head2 The File::Rdiff::Buffers class
92
93	This class contains the input and output buffers for the non-blocking interface. It is slightly unusual
94	in that it allows direct manipulation of (some) of it's internal variables.
95
96	=over 4
97
98	=item new File::Rdiff::Buffers [$outsize]
99
100	Creates and initializes a new buffers structure. C<$outsize> specifies
101	the maximum number of bytes to be read into the output scalar until it is
102	considered full. The default is 64k.
103
104	=item $buffers->in($in)
105
106	Set the next block of input to consume. Data will be read from this scalar
107	(no copy will be made!) until all bytes have been consumed or a new input
108	scalar is set.
109
110	=item $out = $buffers->out
111
112	Return the current output data and create a new buffer. Returns C<undef> if no data has been accumulated.
113
114	=item $buffers->eof
115
116	Set the eof flag to true. This indicates that no data is following the current input scalar.
117
118	=item $buffers->avail_in
119
120	Returns the numer of bytes still available for input. If there are no
121	input bytes available but the eof flag is set, returns -1 (to make boolean
122	tests easy to check wether to supply more data easier).
123
124	=item $buffers->avail_out
125
126	Returns the number of bytes still available in the output buffer.
127
128	=item $buffers->size
129
130	The number of bytes that have been accumulated in the current buffer so far.
131
132	=back
133
134	=head2 The File::Rdiff::Job class
135
136	It is possible to have multiple jobs running at the same time. The idea
137	is to create job objects and then drive them incrementally with input or
138	output data until all date has been processed.
139
140	=over 4
141
142	=item new_sig File::Rdiff::Job [$new_block_len[, $strong_sum_len]]
143
144	Create a job that converts a base stream into a signature stream (i.e. creates signatures).
145
146	=item new_loadsig File::Rdiff::Job
147
148	Create a job that converts the input stream into a in-memory
149	File::Rdiff::Signature object. The signature object can be fetched anytime
150	with the C<signature>-method.
151
152	=item new_delta File::Rdiff::Job $signature
153
154	Creates a job that creates (outputs) a delta between the input stream (the
155	newer file) and the file represented by the given signature.
156
157	=item new_patch File::Rdiff::Job $callback_or_filehandle
158
159	Creates a job that patches a file according to the input stream (a delta
160	stream). The single argument is used to read the base file contents. If it
161	is a filehandle, it must be a seekable handle to the base file.
162
163	If it is a coderef, it will be called whenever base file data must be
164	read. Two arguments will be passed: the file offset and the length. The
165	callback should eithe return the data read (must be a string, not a
166	number!) or an error code.
167
168	=item $job->iter($buffers)
169
170	Do as much work as possible given the input and/or output data in the
171	File::Rdiff::Buffers structure and return either C<DONE> when the job is
172	finished, C<BLOCKED> if there aren't enough bytes available in the input
173	or output buffers (in which case you should deplete the output buffer
174	and/or fill the input buffer and loop), or some error code indicating that
175	the operation failed.
176
177	=item $job->signature
178
179	Only valid for C<new_loadsig>, so look there.
180
181	=back
182
183	=head1 SEE ALSO
184
185	L<File::Rsync>, L<rdiff1> (usage example using simple file API), L<rdiff2> (example using nonblocking API).
186
187	=head1 BUGS
188
189	- not well-tested so far.
190
191	- low memory will result in segfaults rather than croaks.
192
193	- no access to statistics yet
194
195	- documentation leaves much to be deserved.
196
197	=head1 AUTHOR
198
199	Marc Lehmann <pcg@goof.com>
200	http://home.schmorp.de/
201
202	=cut
203
204	1;
205