Add ut_snprintf() function. On Windows this needs to be implemented

using auxiliary functions because there is no snprintf-variant on
Windows that behaves exactly as specified in the standard:

* Always return the number of characters that would have been printed
  if the size were unlimited (not including the final `\0').
* Always '\0'-terminate the result
* Do not touch the buffer if size=0, only return the number of characters
  that would have been printed. Can be used to estimate the size needed
  and to allocate it dynamically.

See http://www.freebsd.org/cgi/query-pr.cgi?pr=87260 for the reason why
2 ap variables are used.

Approved by:	Heikki

include/ut0ut.h

@@ -290,6 +290,24 @@ ut_copy_file(
 	FILE*	dest,	/* in: output file */
 	FILE*	src);	/* in: input file to be appended to output */
 
+/**************************************************************************
+snprintf(). */
+
+#ifdef __WIN__
+int
+ut_snprintf(
+				/* out: number of characters that would
+				have been printed if the size were
+				unlimited, not including the terminating
+				'\0'. */
+	char*		str,	/* out: string */
+	size_t		size,	/* in: str size */
+	const char*	fmt,	/* in: format */
+	...);			/* in: format values */
+#else
+#define ut_snprintf	snprintf
+#endif /* __WIN__ */
+
 #ifndef UNIV_NONINL
 #include "ut0ut.ic"
 #endif

ut/ut0ut.c

@@ -528,3 +528,47 @@ ut_copy_file(
 		}
 	} while (len > 0);
 }
+
+/**************************************************************************
+snprintf(). */
+
+#ifdef __WIN__
+#include <stdarg.h>
+int
+ut_snprintf(
+				/* out: number of characters that would
+				have been printed if the size were
+				unlimited, not including the terminating
+				'\0'. */
+	char*		str,	/* out: string */
+	size_t		size,	/* in: str size */
+	const char*	fmt,	/* in: format */
+	...)			/* in: format values */
+{
+	int	res;
+	va_list	ap1;
+	va_list	ap2;
+
+	va_start(ap1, fmt);
+	va_start(ap2, fmt);
+
+	res = _vscprintf(fmt, ap1);
+
+	if (res == -1) {
+		return(-1);
+	}
+
+	if (size > 0) {
+		_vsnprintf(str, size, fmt, ap2);
+
+		if ((size_t)res >= size) {
+			str[size - 1] = '\0';
+		}
+	}
+
+	va_end(ap1);
+	va_end(ap2);
+
+	return(res);
+}
+#endif /* __WIN__ */