🔧 fix bad case when cow hit sso

ez8-co · Jan 28, 2019 · cf2be85 · cf2be85
1 parent 3cfb16a
commit cf2be85
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Showing 3 changed files with 17 additions and 5 deletions.
diff --git a/ut/ut_xpjson.h b/ut/ut_xpjson.h
@@ -303,6 +303,12 @@ TEST(ut_xpjson, read)
 		// case 9 end with backslash in key
 		in = "{\"a\\";
 		EXPECT_THROW(JSON::Reader::read(v, in.c_str(), in.length()), std::logic_error);
+
+		// case 10 bad cow case when hit sso(1/5/9/13 bytes)
+		JSON::Value v2("yyyyy");
+		v = v2; // incorrect treat as cow when cow(sso_len highest bit) is true
+		*const_cast<char*>(v2.c_str()) = 'z';
+		ASSERT_TRUE(v.s() == "yyyyy");
 	}
 	catch(std::exception &e) {
 		printf("Error : %s.", e.what());

diff --git a/ut/ut_xpjsonW.h b/ut/ut_xpjsonW.h
@@ -302,6 +302,12 @@ TEST(ut_xpjsonW, read)
 		// case 9 end with backslash in key
 		in = L"{\"a\\";
 		EXPECT_THROW(JSON::ReaderW::read(v, in.c_str(), in.length()), std::logic_error);
+
+		// case 10 bad cow case when hit sso(1/5 bytes if sizof(wchar_t) is 2; 1 byte if sizof(wchar_t) is 4)
+		JSON::ValueW v2(L"y");
+		v = v2; // incorrect treat as cow when cow(sso_len highest bit) is true
+		*const_cast<wchar_t*>(v2.c_str()) = 'z';
+		ASSERT_TRUE(v.s() == L"y");
 	}
 	catch(std::exception &e) {
 		printf("Error : %s.", e.what());

diff --git a/xpjson.hpp b/xpjson.hpp
@@ -793,10 +793,10 @@ template<> inline void to_string<type, char_t>(type v, JSON_TSTRING(char_t)& out
 
 	protected:
 		unsigned char _type       : 3;
-		mutable bool _sso         : 1; // small string optimization
+		mutable bool _sso         : 1; // small-string-optimization
 		union {
 			struct {     // not sso
-				mutable bool _cow : 1; // used for direct memory access string
+				mutable bool _cow : 1; // used for copy-on-write string
 				bool _e           : 1; // used for string, indicates needs to be escaped or encoded.
 				char              : 2; // reserved
 			};
@@ -937,7 +937,7 @@ namespace JSON
 				case STRING:
 					_sso = true;
 					_sso_len = 0;
-					assign(v.c_str(), v.length(), v._e, v._cow);
+					assign(v.c_str(), v.length(), v._e, !v._sso && v._cow);
 					break;
 				case OBJECT:  _o = new ObjectT<char_t>(*v._o); break;
 				case ARRAY:   _a = new ArrayT<char_t>(*v._a); break;
@@ -1025,7 +1025,7 @@ namespace JSON
 				case INTEGER: _i = v._i;   break;
 				case FLOAT:   _f = v._f;   break;
 				case STRING:
-					assign(v.c_str(), v.length(), v._e, v._cow);
+					assign(v.c_str(), v.length(), v._e, !v._sso && v._cow);
 					break;
 				case OBJECT:  *_o = *v._o; break;
 				case ARRAY:   *_a = *v._a; break;
@@ -1050,7 +1050,7 @@ namespace JSON
 						_e = v._e;
 					}
 					else {
-						assign(v.c_str(), v.length(), v._e, v._cow);
+						assign(v.c_str(), v.length(), v._e, !v._sso && v._cow);
 					}
 					break;
 				case OBJECT:  swap(_o, v._o); break;