#include <u.h>#include <libc.h>#include "limits.h" char *realpath(char *path, char *buffer){	char *s, p[PATH_MAX];	int f, pathlen, n; 	s = nil;	if((f = open(path, OREAD)) >= 0){		if(fd2path(f, p, sizeof(p)) == 0)			s = buffer == nil ? strdup(p) : strcpy(buffer, p);		close(f);	}	if(s == nil){		if(path[0] != '/'){			pathlen = strlen(path);			if(getwd(p, sizeof(p)) == nil || (n = strlen(p))+1+pathlen >= sizeof(p))				return nil;			p[n++] = '/';			strcpy(p+n, path);			path = p;		}else if(strlen(path) >= sizeof(p))			return nil; 		s = cleanname(buffer == nil ? strdup(path) : strcpy(buffer, path));	} 	return s;}