1 files changed, 77 insertions, 0 deletions
diff --git a/git/git.go b/git/git.go
new file mode 100644
index 0000000..c22de51
--- /dev/null
+++ b/git/git.go
@@ -0,0 +1,77 @@
+package git
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"os/exec"
+	"regexp"
+)
+
+type TreeEntry struct {
+	Mode, Type, Object, Name string
+}
+
+var reTreeEntry = regexp.MustCompile("^(\\d+) (\\w+) ([0-9a-f]+)\t(.*)$")
+
+var (
+	ErrUnexpectedLsTreeOutput = errors.New("Unexpected git ls-tree output")
+)
+
+func splitZero(data []byte, atEOF bool) (advance int, token []byte, err error) {
+	if atEOF && len(data) == 0 {
+		return 0, nil, nil
+	}
+	if i := bytes.IndexByte(data, '\x00'); i >= 0 {
+		return i + 1, data[0:i], nil
+	}
+	if atEOF {
+		return len(data), data, nil
+	}
+
+	return 0, nil, nil
+}
+
+func ReadTree(repoPath string, ref string) ([]TreeEntry, error) {
+	cmd := exec.Command("git", "-C", repoPath, "ls-tree", "--full-tree", "-z", ref)
+	var out bytes.Buffer
+	cmd.Stdout = &out
+
+	if err := cmd.Run(); err != nil {
+		return nil, err
+	}
+
+	scanner := bufio.NewScanner(&out)
+	scanner.Split(splitZero)
+
+	entries := []TreeEntry{}
+	for scanner.Scan() {
+		line := scanner.Bytes()
+		m := reTreeEntry.FindSubmatch(line)
+		if m == nil {
+			return nil, ErrUnexpectedLsTreeOutput
+		}
+
+		entries = append(entries, TreeEntry{
+			Mode:   string(m[1]),
+			Type:   string(m[2]),
+			Object: string(m[3]),
+			Name:   string(m[4]),
+		})
+	}
+
+	return entries, nil
+}
+
+func ReadBlob(repoPath string, ref string) ([]byte, error) {
+	var buf bytes.Buffer
+
+	cmd := exec.Command("git", "-C", repoPath, "cat-file", "blob", ref)
+	cmd.Stdout = &buf
+
+	if err := cmd.Run(); err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}