utfutf.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 "utfdef.h"


/*
 * Return pointer to first occurrence of s2 in s1,
 * 0 if none
 */
char*
utfutf(char *s1, char *s2)
{
	char *p;
	long f, n1, n2;
	Rune r;

	n1 = chartorune(&r, s2);
	f = r;
	if(f <= Runesync)		/* represents self */
		return strstr(s1, s2);

	n2 = strlen(s2);
	for(p=s1; p=utfrune(p, f); p+=n1)
		if(strncmp(p, s2, n2) == 0)
			return p;
	return 0;
}