From 2f7614744b7d027688b371dbff650270e56a88c9 Mon Sep 17 00:00:00 2001
From: Jean Boussier <jean.boussier@gmail.com>
Date: Tue, 5 Nov 2024 14:13:42 +0100
Subject: [PATCH] Raise JSON::GeneratorError instead of
 Encoding::UndefinedConversionError

Followup: https://github.com/ruby/json/pull/633

That's what was raised historically. You could argue that this new
exception is more precise, but I've encountered some real production
code that expected the old behavior and that was broken by this change.
---
 ext/json/ext/generator/generator.c |  4 ++++
 java/src/json/ext/Generator.java   | 20 +++++++++++++-------
 lib/json/pure/generator.rb         | 12 ++++++++++--
 test/json/json_generator_test.rb   | 14 +++++++++++---
 4 files changed, 38 insertions(+), 12 deletions(-)

diff --git a/ext/json/ext/generator/generator.c b/ext/json/ext/generator/generator.c
index 09fdd3a1..a04df36d 100644
--- a/ext/json/ext/generator/generator.c
+++ b/ext/json/ext/generator/generator.c
@@ -954,6 +954,10 @@ static VALUE generate_json_rescue(VALUE d, VALUE exc)
     struct generate_json_data *data = (struct generate_json_data *)d;
     fbuffer_free(data->buffer);
 
+    if (RBASIC_CLASS(exc) == rb_path2class("Encoding::UndefinedConversionError")) {
+        exc = rb_exc_new_str(eGeneratorError, rb_funcall(exc, rb_intern("message"), 0));
+    }
+
     rb_exc_raise(exc);
 
     return Qundef;
diff --git a/java/src/json/ext/Generator.java b/java/src/json/ext/Generator.java
index d818ce49..3c8247b9 100644
--- a/java/src/json/ext/Generator.java
+++ b/java/src/json/ext/Generator.java
@@ -17,6 +17,7 @@
 import org.jruby.runtime.ThreadContext;
 import org.jruby.runtime.builtin.IRubyObject;
 import org.jruby.util.ByteList;
+import org.jruby.exceptions.RaiseException;
 
 public final class Generator {
     private Generator() {
@@ -390,14 +391,19 @@ void generate(Session session, RubyString object, ByteList buffer) {
                 RuntimeInfo info = session.getInfo();
                 RubyString src;
 
-                if (object.encoding(session.getContext()) != info.utf8.get()) {
-                    src = (RubyString)object.encode(session.getContext(),
-                                                    info.utf8.get());
-                } else {
-                    src = object;
-                }
+                try {
+                    if (object.encoding(session.getContext()) != info.utf8.get()) {
+                        src = (RubyString)object.encode(session.getContext(),
+                                                        info.utf8.get());
+                    } else {
+                        src = object;
+                    }
 
-                session.getStringEncoder().encode(src.getByteList(), buffer);
+                    session.getStringEncoder().encode(src.getByteList(), buffer);
+                } catch (RaiseException re) {
+                  throw Utils.newException(session.getContext(), Utils.M_GENERATOR_ERROR,
+                   re.getMessage());
+                }
             }
         };
 
diff --git a/lib/json/pure/generator.rb b/lib/json/pure/generator.rb
index 0a563813..0a5c7856 100644
--- a/lib/json/pure/generator.rb
+++ b/lib/json/pure/generator.rb
@@ -347,7 +347,11 @@ def generate(obj)
         if Regexp.method_defined?(:match?)
           private def fast_serialize_string(string, buf) # :nodoc:
             buf << '"'
-            string = string.encode(::Encoding::UTF_8) unless string.encoding == ::Encoding::UTF_8
+            begin
+              string = string.encode(::Encoding::UTF_8) unless string.encoding == ::Encoding::UTF_8
+            rescue Encoding::UndefinedConversionError => error
+              raise GeneratorError, error.message
+            end
             raise GeneratorError, "source sequence is illegal/malformed utf-8" unless string.valid_encoding?
 
             if /["\\\x0-\x1f]/n.match?(string)
@@ -536,7 +540,11 @@ def to_json(state = nil, *args)
               end
               string = self
             else
-              string = encode(::Encoding::UTF_8)
+              begin
+                string = encode(::Encoding::UTF_8)
+              rescue Encoding::UndefinedConversionError => error
+                raise GeneratorError, error.message
+              end
             end
             if state.ascii_only?
               %("#{JSON.utf8_to_json_ascii(string, state.script_safe)}")
diff --git a/test/json/json_generator_test.rb b/test/json/json_generator_test.rb
index f30f9cf4..c829e44c 100755
--- a/test/json/json_generator_test.rb
+++ b/test/json/json_generator_test.rb
@@ -470,12 +470,20 @@ def test_invalid_encoding_string
     end
     assert_includes error.message, "source sequence is illegal/malformed utf-8"
 
-    assert_raise(Encoding::UndefinedConversionError) do
+    assert_raise(JSON::GeneratorError) do
+      JSON.dump("\x82\xAC\xEF".b)
+    end
+
+    assert_raise(JSON::GeneratorError) do
       "\x82\xAC\xEF".b.to_json
     end
 
-    assert_raise(Encoding::UndefinedConversionError) do
-      JSON.dump("\x82\xAC\xEF".b)
+    assert_raise(JSON::GeneratorError) do
+      ["\x82\xAC\xEF".b].to_json
+    end
+
+    assert_raise(JSON::GeneratorError) do
+      { foo: "\x82\xAC\xEF".b }.to_json
     end
   end