README.md
1libgit2 - the Git linkable library
2==================================
3
4| Build Status | |
5| ------------ | - |
6| **master** branch CI builds | [](https://dev.azure.com/libgit2/libgit2/_build/latest?definitionId=7&branchName=master) |
7| **v0.28 branch** CI builds | [](https://dev.azure.com/libgit2/libgit2/_build/latest?definitionId=7&branchName=maint/v0.28) |
8| **v0.27 branch** CI builds | [](https://dev.azure.com/libgit2/libgit2/_build/latest?definitionId=7&branchName=maint/v0.27) |
9| **v0.26 branch** CI builds | [](https://dev.azure.com/libgit2/libgit2/_build/latest?definitionId=7&branchName=maint/v0.26) |
10| **Nightly** builds | [](https://libgit2.visualstudio.com/libgit2/_build/latest?definitionId=9&branchName=master) [](https://dev.azure.com/libgit2/libgit2/_build/latest?definitionId=21?branchName=master) [](https://scan.coverity.com/projects/639) |
11
12`libgit2` is a portable, pure C implementation of the Git core methods
13provided as a linkable library with a solid API, allowing to build Git
14functionality into your application. Language bindings like
15[Rugged](https://github.com/libgit2/rugged) (Ruby),
16[LibGit2Sharp](https://github.com/libgit2/libgit2sharp) (.NET),
17[pygit2](http://www.pygit2.org/) (Python) and
18[NodeGit](http://nodegit.org) (Node) allow you to build Git tooling
19in your favorite language.
20
21`libgit2` is used to power Git GUI clients like
22[GitKraken](https://gitkraken.com/) and [gmaster](https://gmaster.io/)
23and on Git hosting providers like [GitHub](https://github.com/),
24[GitLab](https://gitlab.com/) and
25[Azure DevOps](https://azure.com/devops).
26We perform the merge every time you click "merge pull request".
27
28`libgit2` is licensed under a **very permissive license** (GPLv2 with a special
29Linking Exception). This basically means that you can link it (unmodified)
30with any kind of software without having to release its source code.
31Additionally, the example code has been released to the public domain (see the
32[separate license](examples/COPYING) for more information).
33
34Table of Contents
35=================
36
37* [Quick Start](#quick-start)
38* [Getting Help](#getting-help)
39* [What It Can Do](#what-it-can-do)
40* [Optional dependencies](#optional-dependencies)
41* [Initialization](#initialization)
42* [Threading](#threading)
43* [Conventions](#conventions)
44* [Building libgit2 - Using CMake](#building-libgit2---using-cmake)
45 * [Building](#building)
46 * [Installation](#installation)
47 * [Advanced Usage](#advanced-usage)
48 * [Compiler and linker options](#compiler-and-linker-options)
49 * [MacOS X](#macos-x)
50 * [Android](#android)
51* [Language Bindings](#language-bindings)
52* [How Can I Contribute?](#how-can-i-contribute)
53* [License](#license)
54
55Quick Start
56===========
57
58**Prerequisites** for building libgit2:
59
601. [CMake](https://cmake.org/), and is recommended to be installed into
61 your `PATH`.
622. [Python](https://www.python.org) is used by our test framework, and
63 should be installed into your `PATH`.
643. C compiler: libgit2 is C90 and should compile on most compilers.
65 * Windows: Visual Studio is recommended
66 * Mac: Xcode is recommended
67 * Unix: gcc or clang is recommended.
68
69**Build**
70
711. Create a build directory beneath the libgit2 source directory, and change
72 into it: `mkdir build && cd build`
732. Create the cmake build environment: `cmake ..`
743. Build libgit2: `cmake --build .`
75
76Trouble with these steps? Read our [troubleshooting guide](docs/troubleshooting.md).
77More detailed build guidance is available below.
78
79Getting Help
80============
81
82**Join us on Slack**
83
84Visit [slack.libgit2.org](http://slack.libgit2.org/) to sign up, then join
85us in `#libgit2`. If you prefer IRC, you can also point your client to our
86slack channel once you've registered.
87
88**Getting Help**
89
90If you have questions about the library, please be sure to check out the
91[API documentation](http://libgit2.github.com/libgit2/). If you still have
92questions, reach out to us on Slack or post a question on
93[StackOverflow](http://stackoverflow.com/questions/tagged/libgit2) (with the `libgit2` tag).
94
95**Reporting Bugs**
96
97Please open a [GitHub Issue](https://github.com/libgit2/libgit2/issues) and
98include as much information as possible. If possible, provide sample code
99that illustrates the problem you're seeing. If you're seeing a bug only
100on a specific repository, please provide a link to it if possible.
101
102We ask that you not open a GitHub Issue for help, only for bug reports.
103
104**Reporting Security Issues**
105
106Please have a look at SECURITY.md.
107
108What It Can Do
109==============
110
111libgit2 provides you with the ability to manage Git repositories in the
112programming language of your choice. It's used in production to power many
113applications including GitHub.com, Plastic SCM and Azure DevOps.
114
115It does not aim to replace the git tool or its user-facing commands. Some APIs
116resemble the plumbing commands as those align closely with the concepts of the
117Git system, but most commands a user would type are out of scope for this
118library to implement directly.
119
120The library provides:
121
122* SHA conversions, formatting and shortening
123* abstracted ODB backend system
124* commit, tag, tree and blob parsing, editing, and write-back
125* tree traversal
126* revision walking
127* index file (staging area) manipulation
128* reference management (including packed references)
129* config file management
130* high level repository management
131* thread safety and reentrancy
132* descriptive and detailed error messages
133* ...and more (over 175 different API calls)
134
135As libgit2 is purely a consumer of the Git system, we have to
136adjust to changes made upstream. This has two major consequences:
137
138* Some changes may require us to change provided interfaces. While we try to
139 implement functions in a generic way so that no future changes are required,
140 we cannot promise a completely stable API.
141* As we have to keep up with changes in behavior made upstream, we may lag
142 behind in some areas. We usually to document these incompatibilities in our
143 issue tracker with the label "git change".
144
145Optional dependencies
146=====================
147
148While the library provides git functionality without the need for
149dependencies, it can make use of a few libraries to add to it:
150
151- pthreads (non-Windows) to enable threadsafe access as well as multi-threaded pack generation
152- OpenSSL (non-Windows) to talk over HTTPS and provide the SHA-1 functions
153- LibSSH2 to enable the SSH transport
154- iconv (OSX) to handle the HFS+ path encoding peculiarities
155
156Initialization
157===============
158
159The library needs to keep track of some global state. Call
160
161 git_libgit2_init();
162
163before calling any other libgit2 functions. You can call this function many times. A matching number of calls to
164
165 git_libgit2_shutdown();
166
167will free the resources. Note that if you have worker threads, you should
168call `git_libgit2_shutdown` *after* those threads have exited. If you
169require assistance coordinating this, simply have the worker threads call
170`git_libgit2_init` at startup and `git_libgit2_shutdown` at shutdown.
171
172Threading
173=========
174
175See [threading](docs/threading.md) for information
176
177Conventions
178===========
179
180See [conventions](docs/conventions.md) for an overview of the external
181and internal API/coding conventions we use.
182
183Building libgit2 - Using CMake
184==============================
185
186Building
187--------
188
189`libgit2` builds cleanly on most platforms without any external dependencies.
190Under Unix-like systems, like Linux, \*BSD and Mac OS X, libgit2 expects `pthreads` to be available;
191they should be installed by default on all systems. Under Windows, libgit2 uses the native Windows API
192for threading.
193
194The `libgit2` library is built using [CMake](<https://cmake.org/>) (version 2.8 or newer) on all platforms.
195
196On most systems you can build the library using the following commands
197
198 $ mkdir build && cd build
199 $ cmake ..
200 $ cmake --build .
201
202Alternatively you can point the CMake GUI tool to the CMakeLists.txt file and generate platform specific build project or IDE workspace.
203
204Running Tests
205-------------
206
207Once built, you can run the tests from the `build` directory with the command
208
209 $ ctest -V
210
211Alternatively you can run the test suite directly using,
212
213 $ ./libgit2_clar
214
215Invoking the test suite directly is useful because it allows you to execute
216individual tests, or groups of tests using the `-s` flag. For example, to
217run the index tests:
218
219 $ ./libgit2_clar -sindex
220
221To run a single test named `index::racy::diff`, which corresponds to the test
222function [`test_index_racy__diff`](https://github.com/libgit2/libgit2/blob/master/tests/index/racy.c#L23):
223
224 $ ./libgit2_clar -sindex::racy::diff
225
226The test suite will print a `.` for every passing test, and an `F` for any
227failing test. An `S` indicates that a test was skipped because it is not
228applicable to your platform or is particularly expensive.
229
230**Note:** There should be _no_ failing tests when you build an unmodified
231source tree from a [release](https://github.com/libgit2/libgit2/releases),
232or from the [master branch](https://github.com/libgit2/libgit2/tree/master).
233Please contact us or [open an issue](https://github.com/libgit2/libgit2/issues)
234if you see test failures.
235
236Installation
237------------
238
239To install the library you can specify the install prefix by setting:
240
241 $ cmake .. -DCMAKE_INSTALL_PREFIX=/install/prefix
242 $ cmake --build . --target install
243
244Advanced Usage
245--------------
246
247For more advanced use or questions about CMake please read <https://cmake.org/Wiki/CMake_FAQ>.
248
249The following CMake variables are declared:
250
251- `BIN_INSTALL_DIR`: Where to install binaries to.
252- `LIB_INSTALL_DIR`: Where to install libraries to.
253- `INCLUDE_INSTALL_DIR`: Where to install headers to.
254- `BUILD_SHARED_LIBS`: Build libgit2 as a Shared Library (defaults to ON)
255- `BUILD_CLAR`: Build [Clar](https://github.com/vmg/clar)-based test suite (defaults to ON)
256- `THREADSAFE`: Build libgit2 with threading support (defaults to ON)
257
258To list all build options and their current value, you can do the
259following:
260
261 # Create and set up a build directory
262 $ mkdir build
263 $ cmake ..
264 # List all build options and their values
265 $ cmake -L
266
267Compiler and linker options
268---------------------------
269
270CMake lets you specify a few variables to control the behavior of the
271compiler and linker. These flags are rarely used but can be useful for
27264-bit to 32-bit cross-compilation.
273
274- `CMAKE_C_FLAGS`: Set your own compiler flags
275- `CMAKE_FIND_ROOT_PATH`: Override the search path for libraries
276- `ZLIB_LIBRARY`, `OPENSSL_SSL_LIBRARY` AND `OPENSSL_CRYPTO_LIBRARY`:
277Tell CMake where to find those specific libraries
278
279MacOS X
280-------
281
282If you want to build a universal binary for Mac OS X, CMake sets it
283all up for you if you use `-DCMAKE_OSX_ARCHITECTURES="i386;x86_64"`
284when configuring.
285
286Android
287-------
288
289Extract toolchain from NDK using, `make-standalone-toolchain.sh` script.
290Optionally, crosscompile and install OpenSSL inside of it. Then create CMake
291toolchain file that configures paths to your crosscompiler (substitute `{PATH}`
292with full path to the toolchain):
293
294 SET(CMAKE_SYSTEM_NAME Linux)
295 SET(CMAKE_SYSTEM_VERSION Android)
296
297 SET(CMAKE_C_COMPILER {PATH}/bin/arm-linux-androideabi-gcc)
298 SET(CMAKE_CXX_COMPILER {PATH}/bin/arm-linux-androideabi-g++)
299 SET(CMAKE_FIND_ROOT_PATH {PATH}/sysroot/)
300
301 SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
302 SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
303 SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
304
305Add `-DCMAKE_TOOLCHAIN_FILE={pathToToolchainFile}` to cmake command
306when configuring.
307
308Language Bindings
309==================================
310
311Here are the bindings to libgit2 that are currently available:
312
313* C++
314 * libqgit2, Qt bindings <https://projects.kde.org/projects/playground/libs/libqgit2/repository/>
315* Chicken Scheme
316 * chicken-git <https://wiki.call-cc.org/egg/git>
317* D
318 * dlibgit <https://github.com/s-ludwig/dlibgit>
319* Delphi
320 * GitForDelphi <https://github.com/libgit2/GitForDelphi>
321* Erlang
322 * Geef <https://github.com/carlosmn/geef>
323* Go
324 * git2go <https://github.com/libgit2/git2go>
325* GObject
326 * libgit2-glib <https://wiki.gnome.org/Projects/Libgit2-glib>
327* Guile
328 * Guile-Git <https://gitlab.com/guile-git/guile-git>
329* Haskell
330 * hgit2 <https://github.com/jwiegley/gitlib>
331* Java
332 * Jagged <https://github.com/ethomson/jagged>
333* Julia
334 * LibGit2.jl <https://github.com/jakebolewski/LibGit2.jl>
335* Lua
336 * luagit2 <https://github.com/libgit2/luagit2>
337* .NET
338 * libgit2sharp <https://github.com/libgit2/libgit2sharp>
339* Node.js
340 * nodegit <https://github.com/nodegit/nodegit>
341* Objective-C
342 * objective-git <https://github.com/libgit2/objective-git>
343* OCaml
344 * ocaml-libgit2 <https://github.com/fxfactorial/ocaml-libgit2>
345* Parrot Virtual Machine
346 * parrot-libgit2 <https://github.com/letolabs/parrot-libgit2>
347* Perl
348 * Git-Raw <https://github.com/jacquesg/p5-Git-Raw>
349* PHP
350 * php-git <https://github.com/libgit2/php-git>
351* PowerShell
352 * PSGit <https://github.com/PoshCode/PSGit>
353* Python
354 * pygit2 <https://github.com/libgit2/pygit2>
355* R
356 * git2r <https://github.com/ropensci/git2r>
357* Ruby
358 * Rugged <https://github.com/libgit2/rugged>
359* Rust
360 * git2-rs <https://github.com/rust-lang/git2-rs>
361* Swift
362 * SwiftGit2 <https://github.com/SwiftGit2/SwiftGit2>
363* Vala
364 * libgit2.vapi <https://github.com/apmasell/vapis/blob/master/libgit2.vapi>
365
366If you start another language binding to libgit2, please let us know so
367we can add it to the list.
368
369How Can I Contribute?
370==================================
371
372We welcome new contributors! We have a number of issues marked as
373["up for grabs"](https://github.com/libgit2/libgit2/issues?q=is%3Aissue+is%3Aopen+label%3A%22up+for+grabs%22)
374and
375["easy fix"](https://github.com/libgit2/libgit2/issues?utf8=✓&q=is%3Aissue+is%3Aopen+label%3A%22easy+fix%22)
376that are good places to jump in and get started. There's much more detailed
377information in our list of [outstanding projects](docs/projects.md).
378
379Please be sure to check the [contribution guidelines](docs/contributing.md) to
380understand our workflow, and the libgit2 [coding conventions](docs/conventions.md).
381
382License
383==================================
384
385`libgit2` is under GPL2 **with linking exception**. This means you can link to
386and use the library from any program, proprietary or open source; paid or
387gratis. However, if you modify libgit2 itself, you must distribute the
388source to your modified version of libgit2.
389
390See the [COPYING file](COPYING) for the full license text.
391
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