Add geef:oid_fmt(Oid)

c_src/oid.c

@@ -0,0 +1,24 @@
+#include <git2.h>
+#include "geef.h"
+#include "oid.h"
+
+ERL_NIF_TERM
+geef_oid_fmt(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
+{
+	ErlNifBinary bin, bin_out;
+	git_oid id;
+
+	if (!enif_inspect_binary(env, argv[0], &bin))
+		return enif_make_badarg(env);
+
+	if (bin.size < GIT_OID_RAWSZ)
+		return enif_make_badarg(env);
+
+	if (!enif_alloc_binary(GIT_OID_HEXSZ, &bin_out))
+		return atoms.error;
+
+	git_oid_fromraw(&id, bin.data);
+	git_oid_fmt((char *)bin_out.data, &id);
+
+	return enif_make_binary(env, &bin_out);
+}