From 85c9b5c00f9c010cfc94907878c85585080af15d Mon Sep 17 00:00:00 2001
From: Matthias Kruk <matthias.kruk@miraclelinux.com>
Date: Fri, 18 Jun 2021 16:25:08 +0900
Subject: [PATCH] include/is: Add is_base64() function

This commit adds is_base64(), a convenience function that allows the
caller to check if a string is base64 encoded.
---
 include/is.sh | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/include/is.sh b/include/is.sh
index d2c39c5..ea8453a 100644
--- a/include/is.sh
+++ b/include/is.sh
@@ -1,4 +1,4 @@
-#!bin/bash
+#!/bin/bash
 
 # is.sh - ctype-style functions for Toolbox
 # Copyright (C) 2021 Matthias Kruk
@@ -44,6 +44,23 @@ is_hex() {
 	return 1
 }
 
+is_base64() {
+	local str="$1"
+
+	# The length must be a multiple of 4 and there
+	# must not be more than two bytes of padding.
+
+	if (( ${#str} % 4 != 0 )); then
+		return 1
+	fi
+
+	if [[ "$str" =~ ^[a-zA-Z0-9+/]+[=]{,2}$ ]]; then
+		return 0
+	fi
+
+	return 1
+}
+
 is_upper() {
 	local str
 
-- 
2.47.3