runevsnprint.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

/*
 * The authors of this software are Rob Pike and Ken Thompson.
 *              Copyright (c) 2002 by Lucent Technologies.
 * Permission to use, copy, modify, and distribute this software for any
 * purpose without fee is hereby granted, provided that this entire notice
 * is included in all copies of any software which is or includes a copy
 * or modification of this software and in all copies of the supporting
 * documentation for such software.
 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTY.  IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
 * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
 */
#include <stdarg.h>
#include <string.h>
#include "utf.h"
#include "fmt.h"
#include "fmtdef.h"

int
runevsnprint(Rune *buf, int len, char *fmt, va_list args)
{
	Fmt f;

	if(len <= 0)
		return -1;
	f.runes = 1;
	f.start = buf;
	f.to = buf;
	f.stop = buf + len - 1;
	f.flush = nil;
	f.farg = nil;
	f.nfmt = 0;
	f.args = args;
	dofmt(&f, fmt);
	*(Rune*)f.to = '\0';
	return (Rune*)f.to - buf;
}