How to commit to a git repository using libgit2? - c++

Question

Since there is no copy-paste example for creating a commit without using files on disk with libgit2 as far as I can tell I thought I should add one.
Don't forget that libgit2 is in full development at this time (March 2013) so have a look at official documentation and source code, as new features are added daily:
libgit2 API
headers are very well commented - here's an example
extensive tests may be a source of inspiration
there are some official examples, general.c is a good place to start
inspiration may be found in LibGit2Sharp - here are some tests

Answer 1

bool addGitCommit (
git_repository * repo, git_signature * sign,
const char * content, int content_sz,
const char * message )
{
int rc; /* return code for git_ functions */
git_oid oid_blob; /* the SHA1 for our blob in the tree */
git_oid oid_tree; /* the SHA1 for our tree in the commit */
git_oid oid_commit; /* the SHA1 for our initial commit */
git_blob * blob; /* our blob in the tree */
git_tree * tree_cmt; /* our tree in the commit */
git_treebuilder * tree_bld; /* tree builder */
bool b = false;
/* create a blob from our buffer */
rc = git_blob_create_frombuffer(
&oid_blob,
repo,
content,
content_sz );
if ( rc == 0 ) { /* blob created */
rc = git_blob_lookup( &blob, repo, &oid_blob );
if ( rc == 0 ) { /* blob created and found */
rc = git_treebuilder_create( &tree_bld, NULL );
if ( rc == 0 ) { /* a new tree builder created */
rc = git_treebuilder_insert(
NULL,
tree_bld,
"name-of-the-file.txt",
&oid_blob,
GIT_FILEMODE_BLOB );
if ( rc == 0 ) { /* blob inserted in tree */
rc = git_treebuilder_write(
&oid_tree,
repo,
tree_bld );
if ( rc == 0 ) { /* the tree was written to the database */
rc = git_tree_lookup(
&tree_cmt, repo, &oid_tree );
if ( rc == 0 ) { /*we've got the tree pointer */
rc = git_commit_create(
&oid_commit, repo, "HEAD",
sign, sign, /* same author and commiter */
NULL, /* default UTF-8 encoding */
message,
tree_cmt, 0, NULL );
if ( rc == 0 ) {
b = true;
}
git_tree_free( tree_cmt );
}
}
}
git_treebuilder_free( tree_bld );
}
git_blob_free( blob );
}
}
return b;
}
The repository comes from git_repository_init() or git_repository_open().
The signature comes from git_signature_now() or git_signature_new().
The function updates the HEAD for current branch.
If you do a git status after the function executes you will notice that the file name-of-the-file.txt appears as being deleted. That is because the function does not create an actual file, only an entry in the git database.
Also, note the last arguments of git_commit_create(). 0 and NULL means that this is the first (root) commit. For all other there should be at least a parent commit specified, maybe obtained using git_commit_lookup().
I'm just learning these things. Please improve this answer if you know better.