From b1e3a86776efab78b2f7ee879c5fed0093294bcd Mon Sep 17 00:00:00 2001
From: Scott Boggs <scott@tams.tech>
Date: Sat, 13 Aug 2022 07:35:10 -0400
Subject: [PATCH] Fix null dereference when passing empty slice to
 Base64.encode (#12377)

---
 spec/std/base64_spec.cr | 6 ++++++
 src/base64.cr           | 1 +
 2 files changed, 7 insertions(+)

diff --git a/spec/std/base64_spec.cr b/spec/std/base64_spec.cr
index 47c8c3665750..89e5d863825a 100644
--- a/spec/std/base64_spec.cr
+++ b/spec/std/base64_spec.cr
@@ -48,6 +48,12 @@ describe "Base64" do
     assert_prints base64_strict_encode(slice), "AQEBAQE="
   end
 
+  it "encodes empty slice" do
+    slice = Bytes.empty
+    assert_prints base64_encode(slice), ""
+    assert_prints base64_strict_encode(slice), ""
+  end
+
   it "encodes static array" do
     array = uninitialized StaticArray(UInt8, 5)
     (0...5).each { |i| array[i] = 1_u8 }
diff --git a/src/base64.cr b/src/base64.cr
index edd8813bd887..717d2e7de2ff 100644
--- a/src/base64.cr
+++ b/src/base64.cr
@@ -203,6 +203,7 @@ module Base64
     bytes = chars.to_unsafe
     size = data.size
     cstr = data.to_unsafe
+    return if cstr.null? || size == 0
     endcstr = cstr + size - size % 3 - 3
 
     # process bunch of full triples