Add support for parsing git trailers (#614)

Adds a wrapper for git_message_trailers which returns a slice of trailer
structs.

1 files changed, 42 insertions, 0 deletions

diff --git a/message.go b/message.go
new file mode 100644
index 0000000..255e8d7
--- /dev/null
+++ b/message.go
@@ -0,0 +1,42 @@
+package git
+
+/*
+#include <git2.h>
+*/
+import "C"
+import (
+	"runtime"
+	"unsafe"
+)
+
+// Trailer represents a single git message trailer.
+type Trailer struct {
+	Key   string
+	Value string
+}
+
+// MessageTrailers parses trailers out of a message, returning a slice of
+// Trailer structs. Trailers are key/value pairs in the last paragraph of a
+// message, not including any patches or conflicts that may be present.
+func MessageTrailers(message string) ([]Trailer, error) {
+	var trailersC C.git_message_trailer_array
+
+	messageC := C.CString(message)
+	defer C.free(unsafe.Pointer(messageC))
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	ecode := C.git_message_trailers(&trailersC, messageC)
+	if ecode < 0 {
+		return nil, MakeGitError(ecode)
+	}
+	defer C.git_message_trailer_array_free(&trailersC)
+	trailers := make([]Trailer, trailersC.count)
+	var trailer *C.git_message_trailer
+	for i, p := 0, uintptr(unsafe.Pointer(trailersC.trailers)); i < int(trailersC.count); i, p = i+1, p+unsafe.Sizeof(C.git_message_trailer{}) {
+		trailer = (*C.git_message_trailer)(unsafe.Pointer(p))
+		trailers[i] = Trailer{Key: C.GoString(trailer.key), Value: C.GoString(trailer.value)}
+	}
+	return trailers, nil
+}