From 97a73ef076f39a4edba08853b57995ffe1adcf2c Mon Sep 17 00:00:00 2001
From: Jean Boussier <jean.boussier@gmail.com>
Date: Tue, 5 Nov 2024 12:59:58 +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 +++++++++++++-------
 java/src/json/ext/GeneratorMethods.java |  2 +-
 lib/json/common.rb                      |  2 ++
 lib/json/pure/generator.rb              |  2 ++
 test/json/json_generator_test.rb        | 14 +++++++++++---
 6 files changed, 33 insertions(+), 11 deletions(-)

diff --git a/ext/json/ext/generator/generator.c b/ext/json/ext/generator/generator.c
index 645500d04..80539af6c 100644
--- a/ext/json/ext/generator/generator.c
+++ b/ext/json/ext/generator/generator.c
@@ -1036,6 +1036,10 @@ 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 b149feb36..f76dcb383 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() {
@@ -402,14 +403,19 @@ 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/java/src/json/ext/GeneratorMethods.java b/java/src/json/ext/GeneratorMethods.java
index bde7a18d9..b6ffdf9cf 100644
--- a/java/src/json/ext/GeneratorMethods.java
+++ b/java/src/json/ext/GeneratorMethods.java
@@ -103,7 +103,7 @@ public static class RbString {
         public static IRubyObject to_json(ThreadContext context,
                 IRubyObject vSelf, IRubyObject[] args) {
             return Generator.generateJson(context, (RubyString)vSelf,
-                    Generator.STRING_HANDLER, args);
+                   Generator.STRING_HANDLER, args);
         }
 
         /**
diff --git a/lib/json/common.rb b/lib/json/common.rb
index 84f2a57c8..e679637c4 100644
--- a/lib/json/common.rb
+++ b/lib/json/common.rb
@@ -293,6 +293,8 @@ def generate(obj, opts = nil)
     else
       State.generate(obj, opts)
     end
+  rescue Encoding::UndefinedConversionError => error
+    raise ::JSON::GeneratorError, error.message
   end
 
   # :stopdoc:
diff --git a/lib/json/pure/generator.rb b/lib/json/pure/generator.rb
index 21e765467..05ffb6314 100644
--- a/lib/json/pure/generator.rb
+++ b/lib/json/pure/generator.rb
@@ -557,6 +557,8 @@ def to_json(state = nil, *args)
             else
               %("#{JSON.utf8_to_json(string, state.script_safe)}")
             end
+          rescue Encoding::UndefinedConversionError => error
+            raise ::JSON::GeneratorError, error.message
           end
 
           # Module that holds the extending methods if, the String module is
diff --git a/test/json/json_generator_test.rb b/test/json/json_generator_test.rb
index 112c03b22..3bc7eb80a 100755
--- a/test/json/json_generator_test.rb
+++ b/test/json/json_generator_test.rb
@@ -477,12 +477,20 @@ 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