Fix base64 decoding issue with unpack m

Author: bjfish

CHANGELOG.md

@@ -23,6 +23,7 @@ Bug fixes:
 * Fix handling of `break`, `next` and `redo` in `define_method(name, &block)` methods (#2418).
 * Fix handling of incompatible types in `Float#<=>` (#2432, @chrisseaton).
 * Fix issue with escaping curly braces for `Dir.glob` (#2425).
+* Fix `base64` decoding issue with missing output (#2435).
 
 Compatibility:
 

spec/ruby/library/base64/decode64_spec.rb

@@ -22,4 +22,8 @@
   it "returns a binary encoded string" do
     Base64.decode64("SEk=").encoding.should == Encoding::BINARY
   end
+
+  it "decodes without padding suffix ==" do
+    Base64.decode64("eyJrZXkiOnsibiI6InR0dCJ9fQ").should == "{\"key\":{\"n\":\"ttt\"}}"
+  end
 end

spec/tags/library/base64/decode64_tags.txt

@@ -144,12 +144,12 @@ private byte[] read(ByteBuffer encode) {
             }
 
             if (a != -1) {
-                if (c == -1) {
+                if (c == -1 && s == '=') {
                     if ((b & 15) != 0) {
                         throw new InvalidFormatException("invalid base64");
                     }
                     lElem[index++] = (byte) ((a << 2 | b >> 4) & 255);
-                } else if (s == '=') {
+                } else if (c != -1 && s == '=') {
                     if ((c & 3) != 0) {
                         throw new InvalidFormatException("invalid base64");
                     }
@@ -160,7 +160,7 @@ private byte[] read(ByteBuffer encode) {
         } else {
 
             while (encode.hasRemaining()) {
-                b = c = -1;
+                a = b = c = d = -1;
 
                 // obtain a
                 s = safeGet(encode);
@@ -214,12 +214,13 @@ private byte[] read(ByteBuffer encode) {
                 lElem[index++] = (byte) ((a << 2 | b >> 4) & 255);
                 lElem[index++] = (byte) ((b << 4 | c >> 2) & 255);
                 lElem[index++] = (byte) ((c << 6 | d) & 255);
+                a = -1;
             }
 
             if (a != -1 && b != -1) {
-                if (c == -1 && s == '=') {
+                if (c == -1) {
                     lElem[index++] = (byte) ((a << 2 | b >> 4) & 255);
-                } else if (c != -1 && s == '=') {
+                } else if (c != -1) {
                     lElem[index++] = (byte) ((a << 2 | b >> 4) & 255);
                     lElem[index++] = (byte) ((b << 4 | c >> 2) & 255);
                 }