#include <u.h>#include <libc.h> /* * In place, rewrite name to compress multiple /, eliminate ., and process .. */#define SEP(x)	((x)=='/' || (x) == 0)char*cleanname(char *name){	char *p, *q, *dotdot;	int rooted, erasedprefix; 	rooted = name[0] == '/';	erasedprefix = 0; 	/*	 * invariants:	 *	p points at beginning of path element we're considering.	 *	q points just past the last path element we wrote (no slash).	 *	dotdot points just past the point where .. cannot backtrack	 *		any further (no slash).	 */	p = q = dotdot = name+rooted;	while(*p) {		if(p[0] == '/')	/* null element */			p++;		else if(p[0] == '.' && SEP(p[1])) {			if(p == name)				erasedprefix = 1;			p += 1;	/* don't count the separator in case it is nul */		} else if(p[0] == '.' && p[1] == '.' && SEP(p[2])) {			p += 2;			if(q > dotdot) {	/* can backtrack */				while(--q > dotdot && *q != '/')					;			} else if(!rooted) {	/* /.. is / but ./../ is .. */				if(q != name)					*q++ = '/';				*q++ = '.';				*q++ = '.';				dotdot = q;			}			if(q == name)				erasedprefix = 1;	/* erased entire path via dotdot */		} else {	/* real path element */			if(q != name+rooted)				*q++ = '/';			while((*q = *p) != '/' && *q != 0)				p++, q++;		}	}	if(q == name)	/* empty string is really ``.'' */		*q++ = '.';	*q = '\0';	if(erasedprefix && name[0] == '#'){		/* this was not a #x device path originally - make it not one now */		memmove(name+2, name, strlen(name)+1);		name[0] = '.';		name[1] = '/';	}	return name;}