fix for windows utf-8 input (#840)

Use UTF-16 as input on Windows, since UTF-8 does not work and reads multibyte characters as zeros

Author: aroidzap

Diff for: examples/common.cpp

@@ -16,12 +16,19 @@
 #endif
 
 #if defined (_WIN32)
+#include <fcntl.h>
+#include <io.h>
 #pragma comment(lib,"kernel32.lib")
 extern "C" __declspec(dllimport) void* __stdcall GetStdHandle(unsigned long nStdHandle);
 extern "C" __declspec(dllimport) int __stdcall GetConsoleMode(void* hConsoleHandle, unsigned long* lpMode);
 extern "C" __declspec(dllimport) int __stdcall SetConsoleMode(void* hConsoleHandle, unsigned long dwMode);
 extern "C" __declspec(dllimport) int __stdcall SetConsoleCP(unsigned int wCodePageID);
 extern "C" __declspec(dllimport) int __stdcall SetConsoleOutputCP(unsigned int wCodePageID);
+extern "C" __declspec(dllimport) int __stdcall WideCharToMultiByte(unsigned int CodePage, unsigned long dwFlags, 
+                                                                   const wchar_t * lpWideCharStr, int cchWideChar, 
+                                                                   char * lpMultiByteStr, int cbMultiByte, 
+                                                                   const char * lpDefaultChar, bool * lpUsedDefaultChar);
+#define CP_UTF8 65001
 #endif
 
 bool gpt_params_parse(int argc, char ** argv, gpt_params & params) {
@@ -307,12 +314,20 @@ void win32_console_init(bool enable_color) {
             SetConsoleMode(hConOut, dwMode | 0x4); // ENABLE_VIRTUAL_TERMINAL_PROCESSING (0x4)
         }
         // Set console output codepage to UTF8
-        SetConsoleOutputCP(65001); // CP_UTF8
+        SetConsoleOutputCP(CP_UTF8);
     }
     void* hConIn = GetStdHandle((unsigned long)-10); // STD_INPUT_HANDLE (-10)
     if (hConIn && hConIn != (void*)-1 && GetConsoleMode(hConIn, &dwMode)) {
-        // Set console input codepage to UTF8
-        SetConsoleCP(65001); // CP_UTF8
+        // Set console input codepage to UTF16
+        _setmode(_fileno(stdin), _O_WTEXT);
     }
 }
+
+// Convert a wide Unicode string to an UTF8 string
+void win32_utf8_encode(const std::wstring & wstr, std::string & str) {
+	int size_needed = WideCharToMultiByte(CP_UTF8, 0, &wstr[0], (int)wstr.size(), NULL, 0, NULL, NULL);
+	std::string strTo(size_needed, 0);
+	WideCharToMultiByte(CP_UTF8, 0, &wstr[0], (int)wstr.size(), &strTo[0], size_needed, NULL, NULL);
+	str = strTo;
+}
 #endif

Diff for: examples/common.h

@@ -92,4 +92,5 @@ void set_console_color(console_state & con_st, console_color_t color);
 
 #if defined (_WIN32)
 void win32_console_init(bool enable_color);
+void win32_utf8_encode(const std::wstring & wstr, std::string & str);
 #endif

Diff for: examples/main/main.cpp

@@ -386,10 +386,19 @@ int main(int argc, char ** argv) {
                 std::string line;
                 bool another_line = true;
                 do {
+#if defined(_WIN32)
+                    std::wstring wline;
+                    if (!std::getline(std::wcin, wline)) {
+                        // input stream is bad or EOF received
+                        return 0;
+                    }
+                    win32_utf8_encode(wline, line);
+#else
                     if (!std::getline(std::cin, line)) {
                         // input stream is bad or EOF received
                         return 0;
                     }
+#endif
                     if (line.empty() || line.back() != '\\') {
                         another_line = false;
                     } else {