| #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; |
| } |