Limit max encodings to 256 and raise error

Co-authored-by: Jose Narvaez <[email protected]>

spec/ruby/optional/capi/encoding_spec.rb

@@ -721,4 +721,23 @@
       str.bytes.should == [0, 0x24]
     end
   end
+
+  describe "rb_define_dummy_encoding" do
+    it "defines the dummy encoding" do
+      @s.rb_define_dummy_encoding("FOO")
+      enc = Encoding.find("FOO")
+      enc.should.dummy?
+    end
+
+    it "returns the index of the dummy encoding" do
+      index = @s.rb_define_dummy_encoding("BAR")
+      index.should == Encoding.list.size - 1
+    end
+
+    it "raises EncodingError if too many encodings" do
+      -> {
+        1_000.times {|i| @s.rb_define_dummy_encoding("R_#{i}") }
+      }.should raise_error(EncodingError, "too many encoding (> 256)")
+    end
+  end
 end

spec/ruby/optional/capi/ext/encoding_spec.c

@@ -323,6 +323,10 @@ static VALUE encoding_spec_rb_enc_left_char_head(VALUE self, VALUE str, VALUE of
   return LONG2NUM(result - ptr);
 }
 
+static VALUE encoding_spec_rb_define_dummy_encoding(VALUE self, VALUE name) {
+  return INT2NUM(rb_define_dummy_encoding(RSTRING_PTR(name)));
+}
+
 void Init_encoding_spec(void) {
   VALUE cls;
   native_rb_encoding_pointer = (rb_encoding**) malloc(sizeof(rb_encoding*));
@@ -382,6 +386,7 @@ void Init_encoding_spec(void) {
   rb_define_method(cls, "rb_uv_to_utf8", encoding_spec_rb_uv_to_utf8, 2);
   rb_define_method(cls, "ONIGENC_MBC_CASE_FOLD", encoding_spec_ONIGENC_MBC_CASE_FOLD, 1);
   rb_define_method(cls, "rb_enc_left_char_head", encoding_spec_rb_enc_left_char_head, 2);
+  rb_define_method(cls, "rb_define_dummy_encoding", encoding_spec_rb_define_dummy_encoding, 1);
 }
 
 #ifdef __cplusplus

src/main/java/org/truffleruby/core/encoding/EncodingManager.java

@@ -206,6 +206,10 @@ public synchronized Object[] getEncodingList() {
         return ArrayUtils.copyOf(ENCODING_LIST_BY_ENCODING_INDEX, ENCODING_LIST_BY_ENCODING_INDEX.length);
     }
 
+    public synchronized int getEncodingListSize() {
+        return ENCODING_LIST_BY_ENCODING_INDEX.length;
+    }
+
     @TruffleBoundary
     public RubyEncoding getRubyEncoding(String name) {
         final String normalizedName = name.toLowerCase(Locale.ENGLISH);

src/main/java/org/truffleruby/core/encoding/EncodingNodes.java

@@ -712,6 +712,7 @@ private static RubyEncoding replicate(Node node, String name, RubyEncoding encod
 
     @Primitive(name = "encoding_create_dummy")
     public abstract static class DummyEncodingNode extends EncodingCreationNode {
+        private static int MAX_ENCODINGS = 256;
 
         @Specialization(guards = "strings.isRubyString(nameObject)", limit = "1")
         static RubyArray createDummyEncoding(Object nameObject,
@@ -726,6 +727,12 @@ static RubyArray createDummyEncoding(Object nameObject,
 
         @TruffleBoundary
         private static RubyEncoding createDummy(Node node, String name) {
+            if (getContext(node).getEncodingManager().getEncodingListSize() >= MAX_ENCODINGS) {
+                throw new RaiseException(
+                        getContext(node),
+                        coreExceptions(node).encodingErrorTooManyEncodings(MAX_ENCODINGS, node));
+            }
+
             return getContext(node).getEncodingManager().createDummyEncoding(name);
         }
 

src/main/java/org/truffleruby/core/exception/CoreExceptions.java

@@ -1138,6 +1138,15 @@ public RubyException encodingError(Object string, RubyEncoding encoding, Node cu
         return ExceptionOperations.createRubyException(context, exceptionClass, errorMessage, currentNode, null);
     }
 
+    @TruffleBoundary
+    public RubyException encodingErrorTooManyEncodings(int maxSize, Node currentNode) {
+        RubyClass exceptionClass = context.getCoreLibrary().encodingErrorClass;
+        String message = StringUtils.format("too many encoding (> %d)", maxSize);
+        RubyString errorMessage = StringOperations.createUTF8String(context, language, message);
+
+        return ExceptionOperations.createRubyException(context, exceptionClass, errorMessage, currentNode, null);
+    }
+
     @TruffleBoundary
     public RubyException encodingCompatibilityErrorIncompatible(RubyEncoding a, RubyEncoding b, Node currentNode) {
         return encodingCompatibilityError(