Avoid null terminating characters in strings from Utf8FromUtf16() (#109729)

---------
Co-authored-by: schectman <schectman@google.com>

dev/benchmarks/complex_layout/windows/runner/utils.cpp

@@ -51,16 +51,16 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   }
   int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, nullptr, 0, nullptr, nullptr);
+      -1, nullptr, 0, nullptr, nullptr)
+    -1; // remove the trailing null character
   std::string utf8_string;
-  if (target_length == 0 || target_length > utf8_string.max_size()) {
+  if (target_length <= 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
   int converted_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, utf8_string.data(),
-      target_length, nullptr, nullptr);
+      -1, utf8_string.data(), target_length, nullptr, nullptr);
   if (converted_length == 0) {
     return std::string();
   }

dev/integration_tests/flutter_gallery/windows/runner/utils.cpp

@@ -51,16 +51,17 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   }
   int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, nullptr, 0, nullptr, nullptr);
+      -1, nullptr, 0, nullptr, nullptr)
+    -1; // remove the trailing null character
+  int input_length = (int)wcslen(utf16_string);
   std::string utf8_string;
-  if (target_length == 0 || target_length > utf8_string.max_size()) {
+  if (target_length <= 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
   int converted_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, utf8_string.data(),
-      target_length, nullptr, nullptr);
+      input_length, utf8_string.data(), target_length, nullptr, nullptr);
   if (converted_length == 0) {
     return std::string();
   }

dev/integration_tests/ui/windows/runner/utils.cpp

@@ -51,16 +51,17 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   }
   int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, nullptr, 0, nullptr, nullptr);
+      -1, nullptr, 0, nullptr, nullptr)
+    -1; // remove the trailing null character
+  int input_length = (int)wcslen(utf16_string);
   std::string utf8_string;
-  if (target_length == 0 || target_length > utf8_string.max_size()) {
+  if (target_length <= 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
   int converted_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, utf8_string.data(),
-      target_length, nullptr, nullptr);
+      input_length, utf8_string.data(), target_length, nullptr, nullptr);
   if (converted_length == 0) {
     return std::string();
   }

dev/integration_tests/windows_startup_test/lib/main.dart

@@ -51,7 +51,7 @@ void main() async {
       // which will use the UTF16 to UTF8 utility function to convert them to a
       // std::string, which should equate to the original expected string.
       // TODO(schectman): Remove trailing null from returned string
-      const String expected = 'ABCℵ\x00';
+      const String expected = 'ABCℵ';
       final Int32List codePoints = Int32List.fromList(expected.codeUnits);
       final String converted = await testStringConversion(codePoints);
       return (converted == expected)

dev/integration_tests/windows_startup_test/windows/runner/flutter_window.cpp

@@ -114,6 +114,7 @@ bool FlutterWindow::OnCreate() {
         for (int32_t code_point : code_points) {
           wide_str.push_back((wchar_t)(code_point));
         }
+        wide_str.push_back((wchar_t)0);
         const std::string string = Utf8FromUtf16(wide_str.data());
         result->Success(string);
       } else {

dev/integration_tests/windows_startup_test/windows/runner/utils.cpp

@@ -51,16 +51,17 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   }
   int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, nullptr, 0, nullptr, nullptr);
+      -1, nullptr, 0, nullptr, nullptr)
+    -1; // remove the trailing null character
+  int input_length = (int)wcslen(utf16_string);
   std::string utf8_string;
-  if (target_length == 0 || target_length > utf8_string.max_size()) {
+  if (target_length <= 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
   int converted_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, utf8_string.data(),
-      target_length, nullptr, nullptr);
+      input_length, utf8_string.data(), target_length, nullptr, nullptr);
   if (converted_length == 0) {
     return std::string();
   }

dev/manual_tests/windows/runner/utils.cpp

@@ -51,16 +51,16 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   }
   int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, nullptr, 0, nullptr, nullptr);
+      -1, nullptr, 0, nullptr, nullptr)
+    -1; // remove the trailing null character
   std::string utf8_string;
-  if (target_length == 0 || target_length > utf8_string.max_size()) {
+  if (target_length <= 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
   int converted_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, utf8_string.data(),
-      target_length, nullptr, nullptr);
+      -1, utf8_string.data(), target_length, nullptr, nullptr);
   if (converted_length == 0) {
     return std::string();
   }

examples/api/windows/runner/utils.cpp

@@ -51,16 +51,16 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   }
   int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, nullptr, 0, nullptr, nullptr);
+      -1, nullptr, 0, nullptr, nullptr)
+    -1; // remove the trailing null character
   std::string utf8_string;
-  if (target_length == 0 || target_length > utf8_string.max_size()) {
+  if (target_length <= 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
   int converted_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, utf8_string.data(),
-      target_length, nullptr, nullptr);
+      -1, utf8_string.data(), target_length, nullptr, nullptr);
   if (converted_length == 0) {
     return std::string();
   }

examples/flutter_view/windows/runner/utils.cpp

@@ -51,16 +51,16 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   }
   int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, nullptr, 0, nullptr, nullptr);
+      -1, nullptr, 0, nullptr, nullptr)
+    -1; // remove the trailing null character
   std::string utf8_string;
-  if (target_length == 0 || target_length > utf8_string.max_size()) {
+  if (target_length <= 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
   int converted_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, utf8_string.data(),
-      target_length, nullptr, nullptr);
+      -1, utf8_string.data(), target_length, nullptr, nullptr);
   if (converted_length == 0) {
     return std::string();
   }

examples/hello_world/windows/runner/utils.cpp

@@ -51,16 +51,16 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   }
   int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, nullptr, 0, nullptr, nullptr);
+      -1, nullptr, 0, nullptr, nullptr)
+    -1; // remove the trailing null character
   std::string utf8_string;
-  if (target_length == 0 || target_length > utf8_string.max_size()) {
+  if (target_length <= 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
   int converted_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, utf8_string.data(),
-      target_length, nullptr, nullptr);
+      -1, utf8_string.data(), target_length, nullptr, nullptr);
   if (converted_length == 0) {
     return std::string();
   }

examples/platform_channel/windows/runner/utils.cpp

@@ -49,17 +49,18 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   if (utf16_string == nullptr) {
     return std::string();
   }
-  int target_length =
-      ::WideCharToMultiByte(CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string, -1,
-                            nullptr, 0, nullptr, nullptr);
+  int target_length = ::WideCharToMultiByte(
+      CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
+      -1, nullptr, 0, nullptr, nullptr)
+    -1; // remove the trailing null character
   std::string utf8_string;
-  if (target_length == 0 || target_length > utf8_string.max_size()) {
+  if (target_length <= 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
   int converted_length = ::WideCharToMultiByte(
-      CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string, -1, utf8_string.data(),
-      target_length, nullptr, nullptr);
+      CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
+      -1, utf8_string.data(), target_length, nullptr, nullptr);
   if (converted_length == 0) {
     return std::string();
   }

examples/platform_view/windows/runner/utils.cpp

@@ -51,16 +51,16 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   }
   int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, nullptr, 0, nullptr, nullptr);
+      -1, nullptr, 0, nullptr, nullptr)
+    -1; // remove the trailing null character
   std::string utf8_string;
-  if (target_length == 0 || target_length > utf8_string.max_size()) {
+  if (target_length <= 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
   int converted_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, utf8_string.data(),
-      target_length, nullptr, nullptr);
+      -1, utf8_string.data(), target_length, nullptr, nullptr);
   if (converted_length == 0) {
     return std::string();
   }

packages/flutter_tools/templates/app_shared/windows.tmpl/runner/utils.cpp

@@ -47,16 +47,17 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   }
   int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, nullptr, 0, nullptr, nullptr);
+      -1, nullptr, 0, nullptr, nullptr)
+    -1; // remove the trailing null character
+  int input_length = (int)wcslen(utf16_string);
   std::string utf8_string;
-  if (target_length == 0 || target_length > utf8_string.max_size()) {
+  if (target_length <= 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
   int converted_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, utf8_string.data(),
-      target_length, nullptr, nullptr);
+      input_length, utf8_string.data(), target_length, nullptr, nullptr);
   if (converted_length == 0) {
     return std::string();
   }