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JSON::GeneratorError expose invalid object
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Fix: ruby/json#710

Makes it easier to debug why a given tree of objects can't
be dumped as JSON.

Co-Authored-By: Étienne Barrié <etienne.barrie@gmail.com>
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@byroot @etiennebarrie @hsbt
2 people authored and hsbt committed Nov 26, 2024
1 parent 6805e88 commit 693a793
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Showing 3 changed files with 70 additions and 19 deletions.
54 changes: 41 additions & 13 deletions ext/json/generator/generator.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -71,6 +71,28 @@ static void generate_json_float(FBuffer *buffer, struct generate_json_data *data

static int usascii_encindex, utf8_encindex, binary_encindex;

#ifdef RBIMPL_ATTR_NORETURN
RBIMPL_ATTR_NORETURN()
#endif
static void raise_generator_error_str(VALUE invalid_object, VALUE str)
{
VALUE exc = rb_exc_new_str(eGeneratorError, str);
rb_ivar_set(exc, rb_intern("@invalid_object"), invalid_object);
rb_exc_raise(exc);
}

#ifdef RBIMPL_ATTR_NORETURN
RBIMPL_ATTR_NORETURN()
#endif
static void raise_generator_error(VALUE invalid_object, const char *fmt, ...)
{
va_list args;
va_start(args, fmt);
VALUE str = rb_vsprintf(fmt, args);
va_end(args);
raise_generator_error_str(invalid_object, str);
}

/* Converts in_string to a JSON string (without the wrapping '"'
* characters) in FBuffer out_buffer.
*
Expand Down Expand Up @@ -867,6 +889,17 @@ static inline int enc_utf8_compatible_p(int enc_idx)
return 0;
}

static VALUE encode_json_string_try(VALUE str)
{
return rb_funcall(str, i_encode, 1, Encoding_UTF_8);
}

static VALUE encode_json_string_rescue(VALUE str, VALUE exception)
{
raise_generator_error_str(str, rb_funcall(exception, rb_intern("message"), 0));
return Qundef;
}

static inline VALUE ensure_valid_encoding(VALUE str)
{
int encindex = RB_ENCODING_GET(str);
Expand All @@ -886,7 +919,7 @@ static inline VALUE ensure_valid_encoding(VALUE str)
}
}

str = rb_funcall(str, i_encode, 1, Encoding_UTF_8);
str = rb_rescue(encode_json_string_try, str, encode_json_string_rescue, str);
}
return str;
}
Expand All @@ -909,7 +942,7 @@ static void generate_json_string(FBuffer *buffer, struct generate_json_data *dat
}
break;
default:
rb_raise(rb_path2class("JSON::GeneratorError"), "source sequence is illegal/malformed utf-8");
raise_generator_error(obj, "source sequence is illegal/malformed utf-8");
break;
}
fbuffer_append_char(buffer, '"');
Expand Down Expand Up @@ -957,10 +990,8 @@ static void generate_json_float(FBuffer *buffer, struct generate_json_data *data
char allow_nan = state->allow_nan;
VALUE tmp = rb_funcall(obj, i_to_s, 0);
if (!allow_nan) {
if (isinf(value)) {
rb_raise(eGeneratorError, "%"PRIsVALUE" not allowed in JSON", tmp);
} else if (isnan(value)) {
rb_raise(eGeneratorError, "%"PRIsVALUE" not allowed in JSON", tmp);
if (isinf(value) || isnan(value)) {
raise_generator_error(obj, "%"PRIsVALUE" not allowed in JSON", tmp);
}
}
fbuffer_append_str(buffer, tmp);
Expand Down Expand Up @@ -1008,7 +1039,7 @@ static void generate_json(FBuffer *buffer, struct generate_json_data *data, JSON
default:
general:
if (state->strict) {
rb_raise(eGeneratorError, "%"PRIsVALUE" not allowed in JSON", CLASS_OF(obj));
raise_generator_error(obj, "%"PRIsVALUE" not allowed in JSON", CLASS_OF(obj));
} else if (rb_respond_to(obj, i_to_json)) {
tmp = rb_funcall(obj, i_to_json, 1, vstate_get(data));
Check_Type(tmp, T_STRING);
Expand Down Expand Up @@ -1036,10 +1067,6 @@ 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;
Expand Down Expand Up @@ -1537,10 +1564,11 @@ void Init_generator(void)
VALUE mExt = rb_define_module_under(mJSON, "Ext");
VALUE mGenerator = rb_define_module_under(mExt, "Generator");

rb_global_variable(&eGeneratorError);
eGeneratorError = rb_path2class("JSON::GeneratorError");

rb_global_variable(&eNestingError);
eNestingError = rb_path2class("JSON::NestingError");
rb_gc_register_mark_object(eGeneratorError);
rb_gc_register_mark_object(eNestingError);

cState = rb_define_class_under(mGenerator, "State", rb_cObject);
rb_define_alloc_func(cState, cState_s_allocate);
Expand Down
18 changes: 17 additions & 1 deletion ext/json/lib/json/common.rb
View file
Original file line number Diff line number Diff line change
Expand Up @@ -143,7 +143,23 @@ class CircularDatastructure < NestingError; end
# :startdoc:

# This exception is raised if a generator or unparser error occurs.
class GeneratorError < JSONError; end
class GeneratorError < JSONError
attr_reader :invalid_object

def initialize(message, invalid_object = nil)
super(message)
@invalid_object = invalid_object
end

def detailed_message(...)
if @invalid_object.nil?
super
else
"#{super}\nInvalid object: #{@invalid_object.inspect}"
end
end
end

# For backwards compatibility
UnparserError = GeneratorError # :nodoc:

Expand Down
17 changes: 12 additions & 5 deletions test/json/json_generator_test.rb
View file
Original file line number Diff line number Diff line change
Expand Up @@ -250,17 +250,20 @@ def test_fast_state
end

def test_allow_nan
assert_raise(GeneratorError) { generate([JSON::NaN]) }
error = assert_raise(GeneratorError) { generate([JSON::NaN]) }
assert_same JSON::NaN, error.invalid_object
assert_equal '[NaN]', generate([JSON::NaN], :allow_nan => true)
assert_raise(GeneratorError) { fast_generate([JSON::NaN]) }
assert_raise(GeneratorError) { pretty_generate([JSON::NaN]) }
assert_equal "[\n NaN\n]", pretty_generate([JSON::NaN], :allow_nan => true)
assert_raise(GeneratorError) { generate([JSON::Infinity]) }
error = assert_raise(GeneratorError) { generate([JSON::Infinity]) }
assert_same JSON::Infinity, error.invalid_object
assert_equal '[Infinity]', generate([JSON::Infinity], :allow_nan => true)
assert_raise(GeneratorError) { fast_generate([JSON::Infinity]) }
assert_raise(GeneratorError) { pretty_generate([JSON::Infinity]) }
assert_equal "[\n Infinity\n]", pretty_generate([JSON::Infinity], :allow_nan => true)
assert_raise(GeneratorError) { generate([JSON::MinusInfinity]) }
error = assert_raise(GeneratorError) { generate([JSON::MinusInfinity]) }
assert_same JSON::MinusInfinity, error.invalid_object
assert_equal '[-Infinity]', generate([JSON::MinusInfinity], :allow_nan => true)
assert_raise(GeneratorError) { fast_generate([JSON::MinusInfinity]) }
assert_raise(GeneratorError) { pretty_generate([JSON::MinusInfinity]) }
Expand Down Expand Up @@ -487,9 +490,13 @@ def test_invalid_encoding_string
["\x82\xAC\xEF".b].to_json
end

assert_raise(JSON::GeneratorError) do
{ foo: "\x82\xAC\xEF".b }.to_json
badly_encoded = "\x82\xAC\xEF".b
exception = assert_raise(JSON::GeneratorError) do
{ foo: badly_encoded }.to_json
end

assert_kind_of EncodingError, exception.cause
assert_same badly_encoded, exception.invalid_object
end

class MyCustomString < String
Expand Down

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