1 3d7e9092 2003-10-14 devnull #include <u.h>
 2 3d7e9092 2003-10-14 devnull #include <libc.h>
 3 3d7e9092 2003-10-14 devnull 
 4 3d7e9092 2003-10-14 devnull /*
 5 3d7e9092 2003-10-14 devnull  * In place, rewrite name to compress multiple /, eliminate ., and process ..
 6 3d7e9092 2003-10-14 devnull  */
 7 3d7e9092 2003-10-14 devnull #define SEP(x)	((x)=='/' || (x) == 0)
 8 3d7e9092 2003-10-14 devnull char*
 9 3d7e9092 2003-10-14 devnull cleanname(char *name)
10 3d7e9092 2003-10-14 devnull {
11 3d7e9092 2003-10-14 devnull 	char *p, *q, *dotdot;
12 3d7e9092 2003-10-14 devnull 	int rooted;
13 3d7e9092 2003-10-14 devnull 
14 3d7e9092 2003-10-14 devnull 	rooted = name[0] == '/';
15 3d7e9092 2003-10-14 devnull 
16 3d7e9092 2003-10-14 devnull 	/*
17 3d7e9092 2003-10-14 devnull 	 * invariants:
18 3d7e9092 2003-10-14 devnull 	 *	p points at beginning of path element we're considering.
19 3d7e9092 2003-10-14 devnull 	 *	q points just past the last path element we wrote (no slash).
20 3d7e9092 2003-10-14 devnull 	 *	dotdot points just past the point where .. cannot backtrack
21 3d7e9092 2003-10-14 devnull 	 *		any further (no slash).
22 3d7e9092 2003-10-14 devnull 	 */
23 3d7e9092 2003-10-14 devnull 	p = q = dotdot = name+rooted;
24 3d7e9092 2003-10-14 devnull 	while(*p) {
25 3d7e9092 2003-10-14 devnull 		if(p[0] == '/')	/* null element */
26 3d7e9092 2003-10-14 devnull 			p++;
27 3d7e9092 2003-10-14 devnull 		else if(p[0] == '.' && SEP(p[1]))
28 3d7e9092 2003-10-14 devnull 			p += 1;	/* don't count the separator in case it is nul */
29 3d7e9092 2003-10-14 devnull 		else if(p[0] == '.' && p[1] == '.' && SEP(p[2])) {
30 3d7e9092 2003-10-14 devnull 			p += 2;
31 3d7e9092 2003-10-14 devnull 			if(q > dotdot) {	/* can backtrack */
32 3d7e9092 2003-10-14 devnull 				while(--q > dotdot && *q != '/')
33 3d7e9092 2003-10-14 devnull 					;
34 3d7e9092 2003-10-14 devnull 			} else if(!rooted) {	/* /.. is / but ./../ is .. */
35 3d7e9092 2003-10-14 devnull 				if(q != name)
36 3d7e9092 2003-10-14 devnull 					*q++ = '/';
37 3d7e9092 2003-10-14 devnull 				*q++ = '.';
38 3d7e9092 2003-10-14 devnull 				*q++ = '.';
39 3d7e9092 2003-10-14 devnull 				dotdot = q;
40 3d7e9092 2003-10-14 devnull 			}
41 3d7e9092 2003-10-14 devnull 		} else {	/* real path element */
42 3d7e9092 2003-10-14 devnull 			if(q != name+rooted)
43 3d7e9092 2003-10-14 devnull 				*q++ = '/';
44 3d7e9092 2003-10-14 devnull 			while((*q = *p) != '/' && *q != 0)
45 3d7e9092 2003-10-14 devnull 				p++, q++;
46 3d7e9092 2003-10-14 devnull 		}
47 3d7e9092 2003-10-14 devnull 	}
48 3d7e9092 2003-10-14 devnull 	if(q == name)	/* empty string is really ``.'' */
49 3d7e9092 2003-10-14 devnull 		*q++ = '.';
50 3d7e9092 2003-10-14 devnull 	*q = '\0';
51 3d7e9092 2003-10-14 devnull 	return name;
52 3d7e9092 2003-10-14 devnull }