xref: /plan9/sys/src/cmd/unix/drawterm/libc/runestrstr.c (revision 8ccd4a6360d974db7bd7bbd4f37e7018419ea908)
1 #include <u.h>
2 #include <libc.h>
3 
4 /*
5  * Return pointer to first occurrence of s2 in s1,
6  * 0 if none
7  */
8 Rune*
runestrstr(Rune * s1,Rune * s2)9 runestrstr(Rune *s1, Rune *s2)
10 {
11 	Rune *p, *pa, *pb;
12 	int c0, c;
13 
14 	c0 = *s2;
15 	if(c0 == 0)
16 		return s1;
17 	s2++;
18 	for(p=runestrchr(s1, c0); p; p=runestrchr(p+1, c0)) {
19 		pa = p;
20 		for(pb=s2;; pb++) {
21 			c = *pb;
22 			if(c == 0)
23 				return p;
24 			if(c != *++pa)
25 				break;
26 		}
27 	}
28 	return 0;
29 }
30