This is a pure-Erlang implementation of a bunch of Git functionality.

Currently it is capable of reading Git objects out of loose or packfile formats and parsing tree and commit objects into more meaningful data structures.

It is currently slower than a slow-motion replay of a cold-weather molasses drip-race judged by sloths who just took Nyquil. Slowly.

To compile ErlanGit, run the following from within the project directory:

$ rake build

To test that everything is working properly, run the tests:

$ rake

When you run the test, the project is built with tests enabled. Before deploying to a production system make sure you do a normal build.

First you initialize a Git object with the path to a Git repository:

Git = git:open("test_git")

You can get the type, size and data for any object in Git with the git:object_data call:

{Type, Size, Data} = git:object_data(Git, "8d47f3435ce5dfd0b2ab5758590c2db21b5294b4")

Type is a term (one of commit, tree, blob, tag), Size is an int of the size of the object and Data is a binary of the object data.

You can use object_exists to get a true/false back as to if a given object exists in the database.

Result = git:object_exists(Git, "8d47f3435ce5dfd0b2ab5758590c2db21b5294b4")

You can get a topographically ordered listing of the commit SHAs reachable froma given array of commit SHAs with the git:rev_list command

RevList = git:rev_list(Git, ["25daa907ccb6feb267bfec70a130d5fe13e48a79"])

That command will return an array of commit SHA strings:

RevList: ["25daa907ccb6feb267bfec70a130d5fe13e48a79",
        "dd991a4966e8807d448305e67a9b3727efc6060c",
        "be62addb149d286893e2ec254e0dc783a871e8af",
        "208fc4a6a08fb1e5136cf9943d79ad81097a0f36",
        "ef8285c69ceac3f2ff2fee154d3d6ad6a71fb826",
        "61fa970afbf82f79611220203213cd9562a809e3",
        "a361a3163a1b521f277e3877232d94b787750c36"]

You can get formatted data back for tree and commit objects (and blobs, but it just returns a string of the blob) with the git:object/2 call

{ok, Commit} = git:object(Git, "25daa907ccb6feb267bfec70a130d5fe13e48a79")

That will return a Commit object who's record looks like this:

-record(commit, {sha, parents, tree,
               author, committer, encoding, message}).

So you can then get the array of parent SHAs with Commit#commit.parents, or the commit message with Commit#commit.message.

If you run git:object/2 with a tree SHA, it will give you back an array of tree entries, each of which is a tree record:

-record(tree, {mode, name, sha}).

There are also a few output functions to help look at the data returned. You can get the equivalent of the 'git log' output with the git_io:print_log command.

git_io:print_log(Git, ["25daa907ccb6feb267bfec70a130d5fe13e48a79"])

That will print to stdout something like this:

commit 61fa970afbf82f79611220203213cd9562a809e3
Author: Scott Chacon <schacon@gmail.com> 1258278496 +0100

added test one

commit a361a3163a1b521f277e3877232d94b787750c36
Author: Scott Chacon <schacon@gmail.com> 1258278448 +0100

first commit