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Revision: 1.1
Committed: Tue Mar 8 20:18:52 2005 UTC (19 years, 4 months ago) by root
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# Content
1 NAME
2 File::Rdiff -- generate remote signatures and patch files using librsync
3
4 SYNOPSIS
5 use File::Rdiff
6
7 DESCRIPTION
8 A more-or-less direct interface to librsync (<http://rproxy.samba.org>).
9
10 For usage examples (better than this very sparse documentation), see the
11 two example scripts rdiff1 and rdiff2 that came with the distribution.
12
13 LIBRSYNC_VERSION
14 A constant describing the version of the rsync library used in this
15 module. My version claimed to be "0.9.5 librsync" when I wrote this
16 document ;)
17
18 $oldlevel = trace_level [$newlevel]
19 Return the current tracelevel and optionally set a new one.
20
21 $oldcb = trace_to [$newcb]
22 Return the current trace callback and optionally set a new one. The
23 callback will be called with the log level as the first argument and
24 the log message as the second one.
25
26 Calling "trace_to" with "undef" will restore the default handler
27 (which currently prints the message to standard error).
28
29 supports_trace
30 Returns wether debugging traces are supported in this version of the
31 library.
32
33 $msg = strerror $rcode
34 Returns a string representation of the given error code. You usually
35 just "exit(1)" or something when a function/method fails, as all
36 (most?) librsync functions log the error properly, so there is
37 rarely a need to call this function.
38
39 $md4 = md4_file $fh
40 sig_file $old_fh, $sig_fh[, $block_len[, $strong_len]]
41 $sig = loadsig_file $fh
42 delta_file $signature, $new_fh, $delta_fh
43 patch_file $base_fh, $delta_fh, $new_fh
44
45 The File::Rdiff::Job class
46 The File::Rdiff::Buffers class
47 This class contains the input and output buffers for the non-blocking
48 interface. It is slightly unusual in that it allows direct manipulation
49 of (some) of it's internal variables.
50
51 new File::Rdiff::Buffers [$outsize]
52 Creates and initializes a new buffers structure. $outsize specifies
53 the maximum number of bytes to be read into the output scalar until
54 it is considered full. The default is 64k.
55
56 $buffers->in($in)
57 Set the next block of input to consume. Data will be read from this
58 scalar (no copy will be made!) until all bytes have been consumed or
59 a new input scalar is set.
60
61 $out = $buffers->out
62 Return the current output data and create a new buffer. Returns
63 "undef" if no data has been accumulated.
64
65 $buffers->eof
66 Set the eof flag to true. This indicates that no data is following
67 the current input scalar.
68
69 $buffers->avail_in
70 Returns the numer of bytes still available for input. If there are
71 no input bytes available but the eof flag is set, returns -1 (to
72 make boolean tests easy to check wether to supply more data easier).
73
74 $buffers->avail_out
75 Returns the number of bytes still available in the output buffer.
76
77 $buffers->size
78 The number of bytes that have been accumulated in the current buffer
79 so far.
80
81 The File::Rdiff::Job class
82 It is possible to have multiple jobs running at the same time. The idea
83 is to create job objects and then drive them incrementally with input or
84 output data until all date has been processed.
85
86 new_sig File::Rdiff::Job [$new_block_len[, $strong_sum_len]]
87 Create a job that converts a base stream into a signature stream
88 (i.e. creates signatures).
89
90 new_loadsig File::Rdiff::Job
91 Create a job that converts the input stream into a in-memory
92 File::Rdiff::Signature object. The signature object can be fetched
93 anytime with the "signature"-method.
94
95 new_delta File::Rdiff::Job $signature
96 Creates a job that creates (outputs) a delta between the input
97 stream (the newer file) and the file represented by the given
98 signature.
99
100 new_patch File::Rdiff::Job $callback_or_filehandle
101 Creates a job that patches a file according to the input stream (a
102 delta stream). The single argument is used to read the base file
103 contents. If it is a filehandle, it must be a seekable handle to the
104 base file.
105
106 If it is a coderef, it will be called whenever base file data must
107 be read. Two arguments will be passed: the file offset and the
108 length. The callback should eithe return the data read (must be a
109 string, not a number!) or an error code.
110
111 $job->iter($buffers)
112 Do as much work as possible given the input and/or output data in
113 the File::Rdiff::Buffers structure and return either "DONE" when the
114 job is finished, "BLOCKED" if there aren't enough bytes available in
115 the input or output buffers (in which case you should deplete the
116 output buffer and/or fill the input buffer and loop), or some error
117 code indicating that the operation failed.
118
119 $job->signature
120 Only valid for "new_loadsig", so look there.
121
122 SEE ALSO
123 File::Rsync, rdiff1 (usage example using simple file API), rdiff2
124 (example using nonblocking API).
125
126 BUGS
127 - not well-tested so far.
128
129 - low memory will result in segfaults rather than croaks.
130
131 - no access to statistics yet
132
133 - documentation leaves much to be deserved.
134
135 AUTHOR
136 Marc Lehmann <schmorp@schmorp.de>
137 http://home.schmorp.de/
138