1 files changed, 54 insertions, 0 deletions
diff --git a/src/os/user/getgrouplist_darwin.go b/src/os/user/getgrouplist_darwin.go
new file mode 100644
index 0000000..e8fe26c
--- /dev/null
+++ b/src/os/user/getgrouplist_darwin.go
@@ -0,0 +1,54 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build cgo,!osusergo
+
+package user
+
+/*
+#include <unistd.h>
+#include <sys/types.h>
+#include <stdlib.h>
+
+static int mygetgrouplist(const char* user, gid_t group, gid_t* groups, int* ngroups) {
+	int* buf = malloc(*ngroups * sizeof(int));
+	int rv = getgrouplist(user, (int) group, buf, ngroups);
+	int i;
+	if (rv == 0) {
+		for (i = 0; i < *ngroups; i++) {
+			groups[i] = (gid_t) buf[i];
+		}
+	}
+	free(buf);
+	return rv;
+}
+*/
+import "C"
+import (
+	"fmt"
+	"unsafe"
+)
+
+func getGroupList(name *C.char, userGID C.gid_t, gids *C.gid_t, n *C.int) C.int {
+	return C.mygetgrouplist(name, userGID, gids, n)
+}
+
+// groupRetry retries getGroupList with an increasingly large size for n. The
+// result is stored in gids.
+func groupRetry(username string, name []byte, userGID C.gid_t, gids *[]C.gid_t, n *C.int) error {
+	*n = C.int(256 * 2)
+	for {
+		*gids = make([]C.gid_t, *n)
+		rv := getGroupList((*C.char)(unsafe.Pointer(&name[0])), userGID, &(*gids)[0], n)
+		if rv >= 0 {
+			// n is set correctly
+			break
+		}
+		if *n > maxGroups {
+			return fmt.Errorf("user: %q is a member of more than %d groups", username, maxGroups)
+		}
+		*n = *n * C.int(2)
+	}
+	return nil
+}