func traverseExtractTree(repo git.Repo, root *git.Tree, dir string) error {
if _, err := os.Stat(dir); os.IsNotExist(err) {
os.MkdirAll(dir, 0777)
}
for _, item := range root.Items {
switch item.Mode & git.TREE_MODE_DIR {
case 0:
// this is a blob, extract it
// open local file first
path := filepath.Join(dir, item.Name)
file, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE, 0666)
if err != nil {
return err
}
defer file.Close()
// open blob
_, obj, err := repo.OpenObject(item.Hash)
if err != nil {
return err
}
defer obj.Close()
_, err = io.Copy(file, obj)
if err != nil {
return err
}
case git.TREE_MODE_DIR:
// this is a tree, do a recursive extraction
new_dir := filepath.Join(dir, item.Name)
// load tree object
_, obj, err := repo.OpenObject(item.Hash)
if err != nil {
return err
}
new_root, err := git.ReadTree(obj)
if err != nil {
return err
}
obj.Close()
err = traverseExtractTree(repo, new_root, new_dir)
if err != nil {
return err
}
}
}
return nil
}
func ExtractTree(repo git.Repo, branch, build_dir string) error {
// resolve branch
hash, err := repo.ReadRef(branch)
if err != nil {
return err
}
if _, err := os.Stat(build_dir); os.IsNotExist(err) {
os.MkdirAll(build_dir, 0777)
}
// read commit object and extract tree id from it
_, obj, err := repo.OpenObject(hash)
if err != nil {
return err
}
defer obj.Close()
commit, err := git.ReadCommit(obj)
if err != nil {
return err
}
treeId := commit.TreeId
// read root tree object
_, treeObj, err := repo.OpenObject(treeId)
if err != nil {
return err
}
defer treeObj.Close()
root, err := git.ReadTree(treeObj)
if err != nil {
return err
}
// traverse tree from root and extract content into given directory
err = traverseExtractTree(repo, root, build_dir)
if err != nil {
return err
}
return nil
}