ref: 6fcd59e9ec30216fa9e46647e9ad1f3fe92be7a7
dir: /libc/cleanname.c/
#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; rooted = name[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])) 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; } } 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'; return name; }