Append terminator in saveStringFromFreeZone()

extras/tests/JsonDeserializer/string.cpp

@@ -113,3 +113,21 @@ TEST_CASE("Not enough room to save the key") {
             DeserializationError::NoMemory);  // fails in the second string
   }
 }
+
+TEST_CASE("Empty memory pool") {
+  // NOLINTNEXTLINE(clang-analyzer-optin.portability.UnixAPI)
+  DynamicJsonDocument doc(0);
+
+  SECTION("Input is const char*") {
+    REQUIRE(deserializeJson(doc, "\"hello\"") ==
+            DeserializationError::NoMemory);
+    REQUIRE(deserializeJson(doc, "\"\"") == DeserializationError::NoMemory);
+  }
+
+  SECTION("Input is const char*") {
+    char hello[] = "\"hello\"";
+    REQUIRE(deserializeJson(doc, hello) == DeserializationError::Ok);
+    char empty[] = "\"hello\"";
+    REQUIRE(deserializeJson(doc, empty) == DeserializationError::Ok);
+  }
+}

extras/tests/MemoryPool/StringCopier.cpp

@@ -11,12 +11,11 @@ TEST_CASE("StringCopier") {
   char buffer[4096];
 
   SECTION("Works when buffer is big enough") {
-    MemoryPool pool(buffer, addPadding(JSON_STRING_SIZE(6)));
+    MemoryPool pool(buffer, addPadding(JSON_STRING_SIZE(5)));
     StringCopier str(pool);
 
     str.startString();
     str.append("hello");
-    str.append('\0');
 
     REQUIRE(str.isValid() == true);
     REQUIRE(std::string(str.str()) == "hello");
@@ -31,6 +30,7 @@ TEST_CASE("StringCopier") {
     str.append("hello world!");
 
     REQUIRE(str.isValid() == false);
+    REQUIRE(pool.overflowed() == true);
   }
 
   SECTION("Increases size of memory pool") {
@@ -38,10 +38,19 @@ TEST_CASE("StringCopier") {
     StringCopier str(pool);
 
     str.startString();
-    str.append('h');
     str.save();
 
     REQUIRE(1 == pool.size());
+    REQUIRE(pool.overflowed() == false);
+  }
+
+  SECTION("Works when memory pool is 0 bytes") {
+    MemoryPool pool(buffer, 0);
+    StringCopier str(pool);
+
+    str.startString();
+    REQUIRE(str.isValid() == false);
+    REQUIRE(pool.overflowed() == true);
   }
 }
 
@@ -49,7 +58,6 @@ static const char* addStringToPool(MemoryPool& pool, const char* s) {
   StringCopier str(pool);
   str.startString();
   str.append(s);
-  str.append('\0');
   return str.save().c_str();
 }
 

extras/tests/Misc/Utf8.cpp

@@ -18,7 +18,6 @@ static void testCodepoint(uint32_t codepoint, std::string expected) {
   CAPTURE(codepoint);
   Utf8::encodeCodepoint(codepoint, str);
 
-  str.append('\0');
   REQUIRE(str.str().c_str() == expected);
 }
 

extras/tests/Misc/printable.cpp

@@ -60,6 +60,7 @@ TEST_CASE("Printable") {
       CHECK(printable.totalBytesWritten() == 7);
       CHECK(doc.overflowed() == false);
       CHECK(doc.memoryUsage() == 8);
+      CHECK(doc.as<JsonVariant>().memoryUsage() == 8);
     }
 
     SECTION("Via Print::write(const char* size_t)") {
@@ -69,6 +70,7 @@ TEST_CASE("Printable") {
       CHECK(printable.totalBytesWritten() == 7);
       CHECK(doc.overflowed() == false);
       CHECK(doc.memoryUsage() == 8);
+      CHECK(doc.as<JsonVariant>().memoryUsage() == 8);
     }
   }
 

src/ArduinoJson/Json/JsonDeserializer.hpp

@@ -401,8 +401,6 @@ class JsonDeserializer {
       _stringStorage.append(c);
     }
 
-    _stringStorage.append('\0');
-
     if (!_stringStorage.isValid()) {
       _error = DeserializationError::NoMemory;
       return false;
@@ -426,8 +424,6 @@ class JsonDeserializer {
       return false;
     }
 
-    _stringStorage.append('\0');
-
     if (!_stringStorage.isValid()) {
       _error = DeserializationError::NoMemory;
       return false;

src/ArduinoJson/Memory/MemoryPool.hpp

@@ -87,13 +87,14 @@ class MemoryPool {
 
   const char* saveStringFromFreeZone(size_t len) {
 #if ARDUINOJSON_ENABLE_STRING_DEDUPLICATION
-    const char* dup = findString(adaptString(_left));
+    const char* dup = findString(adaptString(_left, len));
     if (dup)
       return dup;
 #endif
 
     const char* str = _left;
     _left += len;
+    *_left++ = 0;
     checkInvariants();
     return str;
   }

src/ArduinoJson/MsgPack/MsgPackDeserializer.hpp

@@ -343,7 +343,6 @@ class MsgPackDeserializer {
         return false;
       _stringStorage.append(static_cast<char>(c));
     }
-    _stringStorage.append('\0');
     if (!_stringStorage.isValid()) {
       _error = DeserializationError::NoMemory;
       return false;

src/ArduinoJson/StringStorage/StringCopier.hpp

@@ -17,10 +17,13 @@ class StringCopier {
   void startString() {
     _pool->getFreeZone(&_ptr, &_capacity);
     _size = 0;
+    if (_capacity == 0)
+      _pool->markAsOverflowed();
   }
 
   string_type save() {
     ARDUINOJSON_ASSERT(_ptr);
+    ARDUINOJSON_ASSERT(_size < _capacity);  // needs room for the terminator
     return _pool->saveStringFromFreeZone(_size);
   }
 
@@ -33,23 +36,24 @@ class StringCopier {
   }
 
   void append(char c) {
-    if (!_ptr)
+    if (_size + 1 < _capacity)
-      return;
+      _ptr[_size++] = c;
-
+    else
-    if (_size >= _capacity) {
-      _ptr = 0;
       _pool->markAsOverflowed();
-      return;
-    }
-
-    _ptr[_size++] = c;
   }
 
-  bool isValid() {
+  bool isValid() const {
-    return _ptr != 0;
+    return !_pool->overflowed();
+  }
+
+  size_t size() const {
+    return _size;
   }
 
   string_type str() const {
+    ARDUINOJSON_ASSERT(_ptr);
+    ARDUINOJSON_ASSERT(_size < _capacity);
+    _ptr[_size] = 0;
     return _ptr;
   }
 

src/ArduinoJson/StringStorage/StringMover.hpp

@@ -20,7 +20,10 @@ class StringMover {
   }
 
   FORCE_INLINE string_type save() {
-    return _startPtr;
+    _writePtr[0] = 0;  // terminator
+    string_type s = str();
+    _writePtr++;
+    return s;
   }
 
   void append(char c) {
@@ -35,6 +38,10 @@ class StringMover {
     return string_type(_startPtr);
   }
 
+  size_t size() const {
+    return size_t(_writePtr - _startPtr);
+  }
+
  private:
   char* _writePtr;
   char* _startPtr;

src/ArduinoJson/Variant/ConverterImpl.hpp

@@ -204,8 +204,7 @@ class MemoryPoolPrint : public Print {
   }
 
   CopiedString str() {
-    _string[_size++] = 0;
+    ARDUINOJSON_ASSERT(_size < _capacity);
-    ARDUINOJSON_ASSERT(_size <= _capacity);
     return _pool->saveStringFromFreeZone(_size);
   }