1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
|
# librsync
librsync is a library for calculating and applying network deltas,
with an interface designed to ease integration into diverse
network applications.
librsync encapsulates the core algorithms of the rsync protocol, which
help with efficient calculation of the differences between two files.
The rsync algorithm is different from most differencing algorithms
because it does not require the presence of the two files to calculate
the delta. Instead, it requires a set of checksums of each block of
one file, which together form a signature for that file. Blocks at
any in the other file which have the same checksum are likely to be
identical, and whatever remains is the difference.
This algorithm transfers the differences between 2 files without
needing both files on the same system.
librsync is for building other programs that transfer files as efficiently
as rsync. You can use librsync in a program you write to do backups,
distribute binary patches to programs, or sync directories to a server
or between peers.
This tree also produces the `rdiff` command-line tool that exposes the key
operations of librsync: generating file signatures, generating the delta from a
signature to a new file, and applying the delta to regenerate the new file
given the old file.
librsync is used by: Dropbox, rdiff-backup, duplicity, and others. If you use
it, please let me know.
## What librsync is not
1. librsync does not implement the rsync wire protocol. If you want to talk to
an rsync server to transfer files you'll need to shell out to `rsync`.
You cannot make use of librsync to talk to an rsync server.
2. librsync does not deal with file metadata or structure, such as filenames,
permissions, or directories. To this library, a file is just a stream of bytes.
Higher-level tools can deal with such issues in a way appropriate to their
users.
3. librsync also does not include any network functions for talking to SSH
or any other server. To access a remote filesystem, you need to provide
your own code or make use of some other virtual filesystem layer.
## Copyright
librsync is copyright 1999-2015 Martin Pool and others.
librsync is distributed under the GNU LGPL v2.1 (see COPYING), which basically
means that you can dynamically link librsync into non-GPL programs, but you
must redistribute the librsync source, with any modifications you have made.
librsync contains the BLAKE2 hash algorithm, written by Samuel Neves and
released under the CC0 public domain
dedication, <http://creativecommons.org/publicdomain/zero/1.0/>.
## Contact
librsync's home is http://librsync.sourcefrog.net/.
Source and bug tracking is at https://github.com/librsync/librsync/.
There are two mailing lists:
- https://groups.google.com/forum/#!forum/librsync-announce
- https://groups.google.com/forum/#!forum/librsync
There are some questions and answers about librsync on stackoverflow.com tagged
`librsync` (http://stackoverflow.com/questions/tagged/librsync).
That is a good place to see if your question has already been answered.
## Downloads
Tarballs and git tags are at https://github.com/librsync/librsync/releases.
## Requirements
To build librsync you will need:
* A C compiler and appropriate headers and libraries
* Make
* `popt` command line parsing library (http://rpm5.org/files/popt/)
* CMake (http://cmake.org/)
## Compiling
Generate the Makefile by running
$ cmake .
After building you can install `rdiff` and `librsync` for system-wide use.
$ make && sudo make install
## Note for Windows
With cygwin you can build using gcc as under a normal unix system. It
is also possible to compile under cygwin using MSVC++. You must have
environment variables needed by MSCV set using the Vcvars32.bat
script. With these variables set, you just do;
$ FIXME test in MSVC
## Versioning
librsync uses the http://semver.org/ approach to versioning.
The solib version is simply the major number of the library version.
See [NEWS.md](NEWS.md) for a list of changes.
## Platforms
librsync should be widely portable. Patches to fix portability bugs are
welcome.
## Documentation
If you are reading this file on GitHub, see
* [librsync.h](src/librsync.h)
If you are reading the Doxygen version of this file, see:
* @ref librsync.h
* @ref rdiff
## Debugging
If you are using GNU libc, you might like to use
MALLOC_CHECK_=2 ./rdiff
to detect some allocation bugs.
librsync has annotations for the SPLINT static checking tool.
## Testing
You can run the tests with `make test`.
**Note that CMake will not automatically build before testing.** This is a bug,
https://github.com/librsync/librsync/issues/49, and a patch to fix it would be
welcome.
You need `make all && make test`.
## Continuous integration
https://travis-ci.org/librsync/librsync
|
