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libgit2.github.io's Introduction

libgit2 - the Git linkable library

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libgit2 is a portable, pure C implementation of the Git core methods provided as a linkable library with a solid API, allowing to build Git functionality into your application. Language bindings like Rugged (Ruby), LibGit2Sharp (.NET), pygit2 (Python) and NodeGit (Node) allow you to build Git tooling in your favorite language.

libgit2 is used to power Git GUI clients like GitKraken and GitButler and on Git hosting providers like GitHub, GitLab and Azure DevOps. We perform the merge every time you click "merge pull request".

libgit2 is licensed under a very permissive license (GPLv2 with a special Linking Exception). This means that you can link against the library with any kind of software without making that software fall under the GPL. Changes to libgit2 would still be covered under its GPL license. Additionally, the example code has been released to the public domain (see the separate license for more information).

Table of Contents

Using libgit2

Most of these instructions assume that you're writing an application in C and want to use libgit2 directly. If you're not using C, and you're writing in a different language or platform like .NET, Node.js, or Ruby, then there is probably a "language binding" that you can use to take care of the messy tasks of calling into native code.

But if you do want to use libgit2 directly - because you're building an application in C - then you may be able use an existing binary. There are packages for the vcpkg and conan package managers. And libgit2 is available in Homebrew and most Linux distributions.

However, these versions may be outdated and we recommend using the latest version if possible. Thankfully libgit2 is not hard to compile.

Quick Start

Prerequisites for building libgit2:

  1. CMake, and is recommended to be installed into your PATH.
  2. Python is used by our test framework, and should be installed into your PATH.
  3. C compiler: libgit2 is C90 and should compile on most compilers.
    • Windows: Visual Studio is recommended
    • Mac: Xcode is recommended
    • Unix: gcc or clang is recommended.

Build

  1. Create a build directory beneath the libgit2 source directory, and change into it: mkdir build && cd build
  2. Create the cmake build environment: cmake ..
  3. Build libgit2: cmake --build .

Trouble with these steps? Read our troubleshooting guide. More detailed build guidance is available below.

Getting Help

Chat with us

Getting Help

If you have questions about the library, please be sure to check out the API documentation. If you still have questions, reach out to us on Slack or post a question on StackOverflow (with the libgit2 tag).

Reporting Bugs

Please open a GitHub Issue and include as much information as possible. If possible, provide sample code that illustrates the problem you're seeing. If you're seeing a bug only on a specific repository, please provide a link to it if possible.

We ask that you not open a GitHub Issue for help, only for bug reports.

Reporting Security Issues

Please have a look at SECURITY.md.

What It Can Do

libgit2 provides you with the ability to manage Git repositories in the programming language of your choice. It's used in production to power many applications including GitHub.com, Plastic SCM and Azure DevOps.

It does not aim to replace the git tool or its user-facing commands. Some APIs resemble the plumbing commands as those align closely with the concepts of the Git system, but most commands a user would type are out of scope for this library to implement directly.

The library provides:

  • SHA conversions, formatting and shortening
  • abstracted ODB backend system
  • commit, tag, tree and blob parsing, editing, and write-back
  • tree traversal
  • revision walking
  • index file (staging area) manipulation
  • reference management (including packed references)
  • config file management
  • high level repository management
  • thread safety and reentrancy
  • descriptive and detailed error messages
  • ...and more (over 175 different API calls)

As libgit2 is purely a consumer of the Git system, we have to adjust to changes made upstream. This has two major consequences:

  • Some changes may require us to change provided interfaces. While we try to implement functions in a generic way so that no future changes are required, we cannot promise a completely stable API.
  • As we have to keep up with changes in behavior made upstream, we may lag behind in some areas. We usually to document these incompatibilities in our issue tracker with the label "git change".

Optional dependencies

While the library provides git functionality without the need for dependencies, it can make use of a few libraries to add to it:

  • pthreads (non-Windows) to enable threadsafe access as well as multi-threaded pack generation
  • OpenSSL (non-Windows) to talk over HTTPS and provide the SHA-1 functions
  • LibSSH2 to enable the SSH transport
  • iconv (OSX) to handle the HFS+ path encoding peculiarities

Initialization

The library needs to keep track of some global state. Call

git_libgit2_init();

before calling any other libgit2 functions. You can call this function many times. A matching number of calls to

git_libgit2_shutdown();

will free the resources. Note that if you have worker threads, you should call git_libgit2_shutdown after those threads have exited. If you require assistance coordinating this, simply have the worker threads call git_libgit2_init at startup and git_libgit2_shutdown at shutdown.

Threading

See threading for information

Conventions

See conventions for an overview of the external and internal API/coding conventions we use.

Building libgit2 - Using CMake

Building

libgit2 builds cleanly on most platforms without any external dependencies. Under Unix-like systems, like Linux, *BSD and Mac OS X, libgit2 expects pthreads to be available; they should be installed by default on all systems. Under Windows, libgit2 uses the native Windows API for threading.

The libgit2 library is built using CMake (version 2.8 or newer) on all platforms.

On most systems you can build the library using the following commands

$ mkdir build && cd build
$ cmake ..
$ cmake --build .

Alternatively you can point the CMake GUI tool to the CMakeLists.txt file and generate platform specific build project or IDE workspace.

If you're not familiar with CMake, a more detailed explanation may be helpful.

Running Tests

Once built, you can run the tests from the build directory with the command

$ ctest -V

Alternatively you can run the test suite directly using,

$ ./libgit2_tests

Invoking the test suite directly is useful because it allows you to execute individual tests, or groups of tests using the -s flag. For example, to run the index tests:

$ ./libgit2_tests -sindex

To run a single test named index::racy::diff, which corresponds to the test function test_index_racy__diff:

$ ./libgit2_tests -sindex::racy::diff

The test suite will print a . for every passing test, and an F for any failing test. An S indicates that a test was skipped because it is not applicable to your platform or is particularly expensive.

Note: There should be no failing tests when you build an unmodified source tree from a release, or from the main branch. Please contact us or open an issue if you see test failures.

Installation

To install the library you can specify the install prefix by setting:

$ cmake .. -DCMAKE_INSTALL_PREFIX=/install/prefix
$ cmake --build . --target install

Advanced Usage

For more advanced use or questions about CMake please read https://cmake.org/Wiki/CMake_FAQ.

The following CMake variables are declared:

  • CMAKE_INSTALL_BINDIR: Where to install binaries to.
  • CMAKE_INSTALL_LIBDIR: Where to install libraries to.
  • CMAKE_INSTALL_INCLUDEDIR: Where to install headers to.
  • BUILD_SHARED_LIBS: Build libgit2 as a Shared Library (defaults to ON)
  • BUILD_TESTS: Build the unit and integration test suites (defaults to ON)
  • USE_THREADS: Build libgit2 with threading support (defaults to ON)

To list all build options and their current value, you can do the following:

# Create and set up a build directory
$ mkdir build
$ cmake ..
# List all build options and their values
$ cmake -L

Compiler and linker options

CMake lets you specify a few variables to control the behavior of the compiler and linker. These flags are rarely used but can be useful for 64-bit to 32-bit cross-compilation.

  • CMAKE_C_FLAGS: Set your own compiler flags
  • CMAKE_FIND_ROOT_PATH: Override the search path for libraries
  • ZLIB_LIBRARY, OPENSSL_SSL_LIBRARY AND OPENSSL_CRYPTO_LIBRARY: Tell CMake where to find those specific libraries
  • LINK_WITH_STATIC_LIBRARIES: Link only with static versions of system libraries

MacOS X

If you want to build a universal binary for Mac OS X, CMake sets it all up for you if you use -DCMAKE_OSX_ARCHITECTURES="i386;x86_64" when configuring.

Android

Extract toolchain from NDK using, make-standalone-toolchain.sh script. Optionally, crosscompile and install OpenSSL inside of it. Then create CMake toolchain file that configures paths to your crosscompiler (substitute {PATH} with full path to the toolchain):

SET(CMAKE_SYSTEM_NAME Linux)
SET(CMAKE_SYSTEM_VERSION Android)

SET(CMAKE_C_COMPILER   {PATH}/bin/arm-linux-androideabi-gcc)
SET(CMAKE_CXX_COMPILER {PATH}/bin/arm-linux-androideabi-g++)
SET(CMAKE_FIND_ROOT_PATH {PATH}/sysroot/)

SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

Add -DCMAKE_TOOLCHAIN_FILE={pathToToolchainFile} to cmake command when configuring.

MinGW

If you want to build the library in MinGW environment with SSH support enabled, you may need to pass -DCMAKE_LIBRARY_PATH="${MINGW_PREFIX}/${MINGW_CHOST}/lib/" flag to CMake when configuring. This is because CMake cannot find the Win32 libraries in MinGW folders by default and you might see an error message stating that CMake could not resolve ws2_32 library during configuration.

Another option would be to install msys2-w32api-runtime package before configuring. This package installs the Win32 libraries into /usr/lib folder which is by default recognized as the library path by CMake. Please note though that this package is meant for MSYS subsystem which is different from MinGW.

Language Bindings

Here are the bindings to libgit2 that are currently available:

If you start another language binding to libgit2, please let us know so we can add it to the list.

How Can I Contribute?

We welcome new contributors! We have a number of issues marked as "up for grabs" and "easy fix" that are good places to jump in and get started. There's much more detailed information in our list of outstanding projects.

Please be sure to check the contribution guidelines to understand our workflow, and the libgit2 coding conventions.

License

libgit2 is under GPL2 with linking exception. This means you can link to and use the library from any program, proprietary or open source; paid or gratis. However, if you modify libgit2 itself, you must distribute the source to your modified version of libgit2.

See the COPYING file for the full license text.

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libgit2.github.io's Issues

git_submodule_lookup is O(N) w.r.t. number of submodules

causing many operations, such as git_rebase_init (which results in calls to git_submodule_lookup several times for each submodule) to be O(N^2).

On a 3.1Ghz MBP with SSD, for example, a single call to git_submodule_lookup in a repository with 4,000 submodules takes over 20ms.

I am very happy to work on this myself and submit a patch, but I wanted to open a discussion and get advice on how to proceed. One suggestion: allow an option to configure a repository to cache this information on first submodule access.

Migrate site from redcarpet to kramdown

Just got this notification after a new build:

The page build completed successfully, but returned the following warning:

You are currently using the 'redcarpet' Markdown engine, which will not be supported on GitHub Pages after May 1st. At that time, your site will use 'kramdown' for markdown rendering instead. To suppress this warning, remove the 'markdown' setting in your site's '_config.yml' file and confirm your site renders as expected. For more information, see https://help.github.com/articles/updating-your-markdown-processor-to-kramdown.

GitHub Pages was recently upgraded to Jekyll 3.0. It may help to confirm you're using the correct dependencies:

https://github.com/blog/2100-github-pages-now-faster-and-simpler-with-jekyll-3-0

For information on troubleshooting Jekyll see:

https://help.github.com/articles/troubleshooting-jekyll-builds

If you have any questions you can contact us by replying to this email.

I had a quick peek at the config and unfortunately there's a number of redcarpet extensions specified (which I'm not familiar with):

markdown: kramdown
redcarpet:
  extensions: ["no_intra_emphasis", "fenced_code_blocks", "autolink", "tables", "with_toc_data"]
exclude: ['Readme.md']

Opening this so we don't forget to do something about it before May 1st.

The git clone simple example at https://libgit2.github.com/docs/guides/101-samples/ hangs before doing anything.

running

int main(int argc, char **av)
{
git_repository *repo = NULL;
const char *path = "/home/example/utils/escape"; // existing empty directory with write permissions
const char *url="https://github.com/dpnishant/jsprime.git";
return git_clone(&repo, url, path, NULL);
}

triggers

assertion "git_atomic_get(&git__n_inits) > 0" failed: file "libgit2/src/global.c", line 384, function: git__global_state
Aborted (core dumped)

Consider removing the nodegit link

libgit2.org lists nodegit as a Node.js binding of libgit2. However, the last stable release of nodegit is from 2020, there are no prebuilt binaries for any supported Node.js version anymore (only Node 16), and it depends on the long-deprecated "request" library that has security vulnerabilities. There are several issues asking about the project state without replies from the maintainers.

Developers looking for a library to use Git in Node.js will likely just get frustrated when they start with using Node.js.

Crash on running UnitTest with git2-15e1193.DLL with Studio vstest.executionengine.exe on Windows Server 2016

We ran into a problem with git2-15e1193.DLL as we change our test environment to Windows Server 2016.
We changed back to 2012 R2 and it runs without issues.

Unhandled exception at 0x00007FFA745E3882 (git2-15e1193.DLL) in vstest.executionengine.exe.7648.dmp: 0xC0000005: Access violation reading location 0x000000000000000C.
If there is a handler for this exception, the program may be safely continued.

Call Stack:

git2-15e1193.DLL!00007ffa8c933882() Unknown
git2-15e1193.DLL!00007ffa8c9c87fa() Unknown
ntdll.dll!LdrpCallInitRoutine() Unknown
ntdll.dll!LdrShutdownThread() Unknown
ntdll.dll!RtlExitUserThread�() Unknown
kernel32.dll!BaseThreadInitThunk�() Unknown
ntdll.dll!RtlUserThreadStart�() Unknown

libqgit2 link broken?

Hi,

it looks like the link to libqgit2 is broken

quickgit.kde.org results in an DNS_PROBE_FINISHED_NXDOMAIN error on chrome.

git_status_list_new stopped creating status

Hi guys, sorry if that's not the correct place for asking this question, but I'm literally desparate. I had my program working perfectly using git_status_list_new, that is the status object was properly initialized and I could do further processing of it.
Yesterday I've run my program and from nowhere, suddenly git_status_list_new cannot initialize status object, that is, status object is nullptr. I didn't touch the code. Don't know what have happened. I wonder if anyone of you happen to come across similar situation?
Any help really appreciated.
Thank you.

change php-git link

Hi there,

it looks like, that choobie is no longer supporting the actual php-git project.
Therefore I opened an issue to inform other that i startet an own project to add PHP 7 support.

The idea is to change the address of the website to this project.
https://github.com/garvins/php-git.git

AndroidStudio 'define inline' problem

I need build in libgit2 by AndroidStudio.
But, below happened on compile error.
Need modify in-line code.
/src/common.h LINE 97


/* Work around C90-conformance issues */
#if !defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L)
# if defined(_MSC_VER)
#  define inline __inline
# elif defined(__GNUC__)
#  define inline __inline__
# else
#  define inline
# endif
#endif

# include <arpa/inet.h>

First git_rebase_next fails in the presence of submodule changes.

rebase.zip

I am using nodegit, but I do not think the problem is in that library as their Rebase.init and Rebase.next functions appear to be passthroughs.

If you attempt to rebase onto a branch where there would be a conflict in a submodule, the very first call to get_rebase_next fails with the message: "uncommitted change would be overwritten by merge". I imagine the problem has to do with the state of the submodule itself (which is not altered by the rebase) being taken as dirty.

I am able to work around this problem (after which I encounter other problems) by synchronizing (via git_submodule_update) the submodule(s) after calling git_rebase_init.

For an example, unzip the attached setup.sh and test.js in the same directory and run $ bash setup.sh. This script will set up the situation such that a base1 repo is ready to rebase its master branch onto origin/master with a conflict in the submodule x. It then executes test.js with node to attempt to start the rebase operation.

Mention of deprecated symbols in 101 samples

Hello,
I am starting to learn the libgit2 API and in the first example I wanted to try I stumbled upon git_indexer_progress: https://libgit2.org/docs/guides/101-samples/#repositories_clone_progress.
Unfortunately, this does not appear anywhere in the reference: https://libgit2.org/libgit2/#HEAD/search/git_transfer_progress.
Further investigation showed that it is simply because it is a deprecated name of git_indexer_progress.

So, I will definitely do a PR for this particular instance, but it would be nice to be able to catch all such symbols automatically if possible.

Do you think there would be a reliable way to do so, or we should try to parse the "deprecated" header ?

Create push Refspec from a remote branch

Given a local branch ref like refs/heads/master and a remote branch ref refs/remotes/origin/foo I cannot find a way with the current api to produce a valid refspec that git_remote_push accepts.

Just concatenating them like so wont work: refs/heads/master:refs/remotes/origin/foo

I have to manually "rename" the remote branch ref with naive string ops to look like refs/heads/foo to produce a valid refspec for pushing to a remote name with a different name.

Looking like this: refs/heads/master:refs/heads/foo

Did I overlook something or how else do I get from a remote branch name to a refspec name that git_remote_push will accept? Or is there simply no API to convert?

Annotated Examples proposal

Hi,

I've recently posted a tutorial on my blog about how to traverse a git repository using libgit2 and C++ and I was wondering if would be a good idea to add it (after some editing) to the annotated examples.

My idea is to copy the code explained, replace C++ code with C and use the same formatting used in the Repository Initialization example.

Please let me know if this is ok before I do it and submit it as pull request.

How to use Git LFS with libgit2?

Hi,

I'm sorry if this seems like a common question, but I can't find any current answer to this. I am using libgit2 and would like to use Git LFS. I thought that creating the corresponding hooks would be enough, but that doesn't make it work

So in short:

  1. Is Git LFS supported?
  2. Are there any resources to implement it?

Thank you very much!

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