[ruby/json] Add allow_invalid_escape parsing option

Ref: ruby/json#939

ruby/json@05cec0cbee

Author: byroot

ext/json/lib/json.rb

@@ -194,6 +194,18 @@
 # When enabled:
 #   JSON.parse(%{"Hello\nWorld"}, allow_control_characters: true) # => "Hello\nWorld"
 #
+# ---
+#
+# Option +allow_invalid_escape+ (boolean) specifies whether to ignore backslahes that are followed
+# by an invalid escape character in strings;
+# defaults to +false+.
+#
+# With the default, +false+:
+#   JSON.parse(%{"Hell\\o"}) # invalid escape character in string (JSON::ParserError)
+#
+# When enabled:
+#   JSON.parse(%{"Hell\\o"}, allow_invalid_escape: true) # => "Hello"
+#
 # ====== Output Options
 #
 # Option +freeze+ (boolean) specifies whether the returned objects will be frozen;

ext/json/parser/parser.c

@@ -7,8 +7,9 @@ static VALUE CNaN, CInfinity, CMinusInfinity;
 
 static ID i_new, i_try_convert, i_uminus, i_encode;
 
-static VALUE sym_max_nesting, sym_allow_nan, sym_allow_trailing_comma, sym_allow_control_characters, sym_symbolize_names, sym_freeze,
-             sym_decimal_class, sym_on_load, sym_allow_duplicate_key;
+static VALUE sym_max_nesting, sym_allow_nan, sym_allow_trailing_comma, sym_allow_control_characters,
+             sym_allow_invalid_escape, sym_symbolize_names, sym_freeze, sym_decimal_class, sym_on_load,
+             sym_allow_duplicate_key;
 
 static int binary_encindex;
 static int utf8_encindex;
@@ -336,6 +337,7 @@ typedef struct JSON_ParserStruct {
     bool allow_nan;
     bool allow_trailing_comma;
     bool allow_control_characters;
+    bool allow_invalid_escape;
     bool symbolize_names;
     bool freeze;
 } JSON_ParserConfig;
@@ -746,6 +748,8 @@ NOINLINE(static) VALUE json_string_unescape(JSON_ParserState *state, JSON_Parser
                         }
                         raise_parse_error_at("invalid ASCII control character in string: %s", state, pe - 1);
                     }
+                } else if (config->allow_invalid_escape) {
+                    APPEND_CHAR(*pe);
                 } else {
                     raise_parse_error_at("invalid escape character in string: %s", state, pe - 1);
                 }
@@ -1435,6 +1439,7 @@ static int parser_config_init_i(VALUE key, VALUE val, VALUE data)
     else if (key == sym_allow_nan)                  { config->allow_nan = RTEST(val); }
     else if (key == sym_allow_trailing_comma)       { config->allow_trailing_comma = RTEST(val); }
     else if (key == sym_allow_control_characters)   { config->allow_control_characters = RTEST(val); }
+    else if (key == sym_allow_invalid_escape)       { config->allow_invalid_escape = RTEST(val); }
     else if (key == sym_symbolize_names)            { config->symbolize_names = RTEST(val); }
     else if (key == sym_freeze)                     { config->freeze = RTEST(val); }
     else if (key == sym_on_load)                    { config->on_load_proc = RTEST(val) ? val : Qfalse; }
@@ -1653,6 +1658,7 @@ void Init_parser(void)
     sym_allow_nan = ID2SYM(rb_intern("allow_nan"));
     sym_allow_trailing_comma = ID2SYM(rb_intern("allow_trailing_comma"));
     sym_allow_control_characters = ID2SYM(rb_intern("allow_control_characters"));
+    sym_allow_invalid_escape = ID2SYM(rb_intern("allow_invalid_escape"));
     sym_symbolize_names = ID2SYM(rb_intern("symbolize_names"));
     sym_freeze = ID2SYM(rb_intern("freeze"));
     sym_on_load = ID2SYM(rb_intern("on_load"));

test/json/json_parser_test.rb

@@ -183,6 +183,14 @@ def test_parse_allowed_control_chars_in_string
     end
   end
 
+  def test_parse_invalid_escape
+    assert_raise JSON::ParserError do
+      parse(%("fo\\o"))
+    end
+
+    assert_equal "foo", parse(%("fo\\o"), allow_invalid_escape: true)
+  end
+
   def test_parse_arrays
     assert_equal([1,2,3], parse('[1,2,3]'))
     assert_equal([1.2,2,3], parse('[1.2,2,3]'))