Add geef:oid_fmt(Oid)

c_src/geef.c

@@ -1,6 +1,7 @@
 #include "erl_nif.h"
 #include "repository.h"
 #include "reference.h"
+#include "oid.h"
 #include "geef.h"
 #include <stdio.h>
 #include <string.h>
@@ -78,6 +79,7 @@ static ErlNifFunc geef_funcs[] =
 	{"reference_lookup", 2, geef_reference_lookup},
 	{"reference_resolve", 1, geef_reference_resolve},
 	{"reference_id", 1, geef_reference_id},
+	{"oid_fmt", 1, geef_oid_fmt},
 };
 
 ERL_NIF_INIT(geef, geef_funcs, load, NULL, NULL, unload)

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);
+}

c_src/oid.h

@@ -0,0 +1,9 @@
+#ifndef GEEF_OID_H
+#define GEEF_OID_H
+
+#include "erl_nif.h"
+#include <git2.h>
+
+ERL_NIF_TERM geef_oid_fmt(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+
+#endif