-#include "mb_wc_common.h"
-#include <wchar.h>
+/*
+ * wctob.c
+ *
+ * Implementation of ISO-C99 wctob() function, supporting it on legacy
+ * Windows versions, for which MSVCRT.DLL doesn't provide it, otherwise
+ * delegating to the Microsoft implementation, except in specific cases
+ * when that implementation may not support the active MBCS codeset.
+ *
+ *
+ * $Id$
+ *
+ * Written by Keith Marshall <keith@users.osdn.me>
+ * Copyright (C) 2020, MinGW.org Project
+ *
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice, this permission notice, and the following
+ * disclaimer shall be included in all copies or substantial portions of
+ * the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OF OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ */
+#include "wcharmap.h"
+
+/* For runtime delegation, we need a mechanism for detection of an
+ * implementation, within the default C runtime DLL; we may use the
+ * MinGW dlfcn emulation, to facilitate this.
+ */
+#include <dlfcn.h>
#include <stdio.h>
-#include <stdlib.h>
-#include <errno.h>
-#define WIN32_LEAN_AND_MEAN
-#include <windows.h>
-
-/* Return just the first byte after translating to multibyte. */
-int wctob (wint_t wc )
-{
- wchar_t w = wc;
- char c;
- int invalid_char = 0;
- if (!WideCharToMultiByte (get_codepage(),
- 0 /* Is this correct flag? */,
- &w, 1, &c, 1, NULL, &invalid_char)
- || invalid_char)
- return EOF;
- return (int) c;
+
+static int __mingw_wctob_fallback( wint_t wc )
+{ /* Fallback function, providing an implementation of the wctob()
+ * function, when none is available within the Microsoft runtime.
+ * This performs a wchar_t to MBCS conversion on the given single
+ * wide character argument, capturing the conversion into a local
+ * buffer, checks that the result occupies exactly one byte, for
+ * which the coercion of that byte value to int is returned, or
+ * otherwise returns EOF.
+ */
+ union { unsigned char u; char c; } retval;
+ return (__mingw_wctomb_convert( &retval.c, 1, &wc, 1 ) == 1)
+ ? (int)(retval.u) : EOF;
+}
+
+int __mingw_wctob( wint_t wc )
+{ /* Wrapper for the wctob() function; this variant will unconditionally
+ * delegate the call to the MinGW fallback implementation, after first
+ * storing the effective codeset index.
+ */
+ (void)(__mingw_wctomb_codeset_init());
+ return __mingw_wctob_fallback( wc );
}
+
+int __msvcrt_wctob( wint_t wc )
+{ /* Wrapper for the wctob() function; it will initially attempt
+ * to delegate the call to a Microsoft-provided implementation,
+ * but if no such implementation can be found, fall back to the
+ * MinGW substitute (defined above).
+ */
+ static int (*redirector_hook)( wchar_t ) = NULL;
+
+ /* MSVCRT.DLL's setlocale() cannot reliably handle code pages with
+ * more than two bytes per code point, (e.g. UTF-7 and UTF-8); thus,
+ * Microsoft's wctob() is likely to be similarly unreliable, so we
+ * always use the MinGW fallback with such code pages.
+ */
+ if( __mingw_wctomb_cur_max_init(__mingw_wctomb_codeset_init()) > 2 )
+ return __mingw_wctob_fallback( wc );
+
+ /* On first time call, we don't know which implementation is to be
+ * selected; look for a Microsoft implementation, which, if available,
+ * may be registered for immediate use on this, and any subsequent,
+ * calls to this function wrapper...
+ */
+ if( (redirector_hook == NULL)
+ && ((redirector_hook = dlsym( RTLD_DEFAULT, "wctob" )) == NULL) )
+
+ /* ...but when no Microsoft implementation can be found, register
+ * the MinGW fall back in its stead.
+ */
+ redirector_hook = __mingw_wctob_fallback;
+
+ /* Finally, delegate the call to whichever implementation has been
+ * registered on first-time call.
+ */
+ return redirector_hook( wc );
+}
+
+/* $RCSfile$: end of file */
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