jehanne/sys/src/lib/jehanne/port/strstr.c

39 lines
853 B
C

/*
* This file is part of the UCB release of Plan 9. It is subject to the license
* terms in the LICENSE file found in the top-level directory of this
* distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
* part of the UCB release of Plan 9, including this file, may be copied,
* modified, propagated, or distributed except according to the terms contained
* in the LICENSE file.
*/
#include <u.h>
#include <libc.h>
/*
* Return pointer to first occurrence of s2 in s1,
* 0 if none
*/
char*
jehanne_strstr(const char *s1, const char *s2)
{
const char *p, *pa, *pb;
int c0, c;
c0 = *s2;
if(c0 == 0)
return (char*)s1;
s2++;
for(p=jehanne_strchr(s1, c0); p; p=jehanne_strchr(p+1, c0)) {
pa = p;
for(pb=s2;; pb++) {
c = *pb;
if(c == 0)
return (char*)p;
if(c != *++pa)
break;
}
}
return 0;
}