win32utf8.cpp

#include "stdafx.h"
#if defined(_WIN32)
# include <stdio.h>
# include <stdlib.h>
# include <wchar.h>
/*We need the following two to set stdin/stdout to binary.*/
# include <io.h>
# include <fcntl.h>
# define WIN32_LEAN_AND_MEAN
# define WIN32_EXTRA_LEAN
# include <windows.h>
# include "win32utf8.h"

static char *utf16_to_utf8(const wchar_t *_src) {
	char   *dst;
	size_t  len;
	size_t  si;
	size_t  di;
	len = wcslen(_src);
	dst = (char *)malloc(sizeof(*dst)*(3 * len + 1));
	if (dst == NULL)return dst;
	for (di = si = 0; si < len; si++) {
		unsigned c0;
		c0 = _src[si];
		if (c0 < 0x80) {
			/*Can be represented by a 1-byte sequence.*/
			dst[di++] = (char)c0;
			continue;
		}
		else if (c0 < 0x800) {
			/*Can be represented by a 2-byte sequence.*/
			dst[di++] = (char)(0xC0 | c0 >> 6);
			dst[di++] = (char)(0x80 | c0 & 0x3F);
			continue;
		}
		else if (c0 >= 0xD800 && c0 < 0xDC00) {
			unsigned c1;
			/*This is safe, because c0 was not 0 and _src is NUL-terminated.*/
			c1 = _src[si + 1];
			if (c1 >= 0xDC00 && c1 < 0xE000) {
				unsigned w;
				/*Surrogate pair.*/
				w = ((c0 & 0x3FF) << 10 | c1 & 0x3FF) + 0x10000;
				/*Can be represented by a 4-byte sequence.*/
				dst[di++] = (char)(0xF0 | w >> 18);
				dst[di++] = (char)(0x80 | w >> 12 & 0x3F);
				dst[di++] = (char)(0x80 | w >> 6 & 0x3F);
				dst[di++] = (char)(0x80 | w & 0x3F);
				si++;
				continue;
			}
		}
		/*Anything else is either a valid 3-byte sequence, an invalid surrogate
		   pair, or 'not a character'.
		  In the latter two cases, we just encode the value as a 3-byte
		   sequence anyway (producing technically invalid UTF-8).
		  Later error handling will detect the problem, with a better
		   chance of giving a useful error message.*/
		dst[di++] = (char)(0xE0 | c0 >> 12);
		dst[di++] = (char)(0x80 | c0 >> 6 & 0x3F);
		dst[di++] = (char)(0x80 | c0 & 0x3F);
	}
	dst[di++] = '\0';
	return dst;
}

typedef LPWSTR *(APIENTRY *command_line_to_argv_w_func)(LPCWSTR cmd_line,
	int *num_args);

/*Make a best-effort attempt to support UTF-8 on Windows.*/
void win32_utf8_setup(int *_argc, const char ***_argv) {
	HMODULE hlib;
	/*We need to set stdin/stdout to binary mode.
	  This is unrelated to UTF-8 support, but it's platform specific and we need
	   to do it in the same places.*/
	_setmode(_fileno(stdin), _O_BINARY);
	_setmode(_fileno(stdout), _O_BINARY);
	hlib = LoadLibraryA("shell32.dll");
	if (hlib != NULL) {
		command_line_to_argv_w_func command_line_to_argv_w;
		/*This function is only available on Windows 2000 or later.*/
		command_line_to_argv_w = (command_line_to_argv_w_func)GetProcAddress(hlib,
			"CommandLineToArgvW");
		if (command_line_to_argv_w != NULL) {
			wchar_t **argvw;
			int       argc;
			argvw = (*command_line_to_argv_w)(GetCommandLineW(), &argc);
			if (argvw != NULL) {
				int ai;
				/*Really, I don't see why argc would ever differ from *_argc, but let's
				   be paranoid.*/
				if (argc > *_argc)argc = *_argc;
				for (ai = 0; ai < argc; ai++) {
					char *argv;
					argv = utf16_to_utf8(argvw[ai]);
					if (argv != NULL)(*_argv)[ai] = argv;
				}
				*_argc = argc;
				LocalFree(argvw);
			}
		}
		FreeLibrary(hlib);
	}
# if defined(CP_UTF8)
	/*This does not work correctly in all environments (it breaks output in
	   mingw32 for me), and requires a Unicode font (e.g., when using the default
	   Raster font, even characters that are available in the font's codepage
	   won't display properly).*/
	   /*SetConsoleOutputCP(CP_UTF8);*/
# endif
}
#endif