Second go at fixing what should have been part of r31927:

* uncommented fwscanf() in wchar.h to make it available
* imported wcsftime() from FreeBSD-8 (which just wraps strftime()), so that we 
  not only declare it, but provide an implementation, too
As a result, the next build of gcc4 should be able to detect full support for wchar_t and in turn activate wchar_t-based template types (like std::wstring).


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@37720 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/posix/wchar.h

@@ -49,7 +49,7 @@ extern wint_t	fputwc(wchar_t, FILE *);
 extern int		fputws(const wchar_t *, FILE *);
 extern int		fwide(FILE *, int);
 extern int		fwprintf(FILE *, const wchar_t *, ...);
-/*extern int		fwscanf(FILE *, const wchar_t *, ...);*/
+extern int		fwscanf(FILE *, const wchar_t *, ...);
 extern wint_t	getwc(FILE *);
 extern wint_t	getwchar(void);
 
@@ -97,8 +97,7 @@ extern int      wcscoll(const wchar_t *ws1, const wchar_t *ws2);
 extern wchar_t	*wcscpy(wchar_t *, const wchar_t *);
 extern size_t	wcscspn(const wchar_t *, const wchar_t *);
 extern wchar_t	*wcsdup(const wchar_t *);
-extern size_t	wcsftime(wchar_t *, size_t, const wchar_t *,
-					const struct tm *);
+extern size_t	wcsftime(wchar_t *, size_t, const wchar_t *, const struct tm *);
 extern size_t	wcslen(const wchar_t *);
 extern wchar_t 	*wcsncat(wchar_t *, const wchar_t *, size_t);
 extern int		wcsncmp(const wchar_t *, const wchar_t *, size_t);

src/system/libroot/posix/time/Jamfile

@@ -19,6 +19,7 @@ MergeObject posix_time.o :
 	strptime.c
 	timelocal.c
 	time.c
+	wcsftime.c
 ;
 
 # Explanations of flags:

src/system/libroot/posix/time/wcsftime.c

@@ -0,0 +1,110 @@
+/*-
+ * Copyright (c) 2002 Tim J. Robbins
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <time.h>
+#include <wchar.h>
+
+
+/*
+ * Convert date and time to a wide-character string.
+ *
+ * This is the wide-character counterpart of strftime(). So that we do not
+ * have to duplicate the code of strftime(), we convert the format string to
+ * multibyte, call strftime(), then convert the result back into wide
+ * characters.
+ *
+ * This technique loses in the presence of stateful multibyte encoding if any
+ * of the conversions in the format string change conversion state. When
+ * stateful encoding is implemented, we will need to reset the state between
+ * format specifications in the format string.
+ */
+size_t
+wcsftime(wchar_t *wcs, size_t maxsize, const wchar_t *format,
+	const struct tm *timeptr)
+{
+	static const mbstate_t initial;
+	mbstate_t mbs;
+	char *dst, *sformat;
+	const char *dstp;
+	const wchar_t *formatp;
+	size_t n, sflen;
+	int sverrno;
+
+	sformat = dst = NULL;
+
+	/*
+	 * Convert the supplied format string to a multibyte representation
+	 * for strftime(), which only handles single-byte characters.
+	 */
+	mbs = initial;
+	formatp = format;
+	sflen = wcsrtombs(NULL, &formatp, 0, &mbs);
+	if (sflen == (size_t)-1)
+		goto error;
+	if ((sformat = malloc(sflen + 1)) == NULL)
+		goto error;
+	mbs = initial;
+	wcsrtombs(sformat, &formatp, sflen + 1, &mbs);
+
+	/*
+	 * Allocate memory for longest multibyte sequence that will fit
+	 * into the caller's buffer and call strftime() to fill it.
+	 * Then, copy and convert the result back into wide characters in
+	 * the caller's buffer.
+	 */
+	if (SIZE_MAX / MB_CUR_MAX <= maxsize) {
+		/* maxsize is prepostorously large - avoid int. overflow. */
+		errno = EINVAL;
+		goto error;
+	}
+	if ((dst = malloc(maxsize * MB_CUR_MAX)) == NULL)
+		goto error;
+	if (strftime(dst, maxsize, sformat, timeptr) == 0)
+		goto error;
+	dstp = dst;
+	mbs = initial;
+	n = mbsrtowcs(wcs, &dstp, maxsize, &mbs);
+	if (n == (size_t)-2 || n == (size_t)-1 || dstp != NULL)
+		goto error;
+
+	free(sformat);
+	free(dst);
+
+	return n;
+
+error:
+	sverrno = errno;
+	free(sformat);
+	free(dst);
+	errno = sverrno;
+
+	return 0;
+}