canonicalize.c

/* Canonicalize virtual path
 * License: public domain
 */

void canonicalize(const char *path, char *output) {
   do {
      while(path[0] == '/') path++;
      char *chunk_end = strchr(path, '/');
      int chunk_length = chunk_end ? chunk_end - path : strlen(path);

      if(chunk_length > 0 && !memcmp(path, ".", chunk_length)) {
         path += chunk_length;
         continue;
      }

      if(chunk_length > 0 && !memcmp(path, "..", chunk_length)) {
         path += chunk_length;
         char *prev = strrchr(output, '/');
         if(prev) memset(prev, 0, strlen(prev));
         continue;
      }

      strcat(output, "/");
      strncat(output, path, chunk_length);

      if(!chunk_end) {
         if(chunk_length > 0) strcat(output, "/");
         break;
      }
      
      path = chunk_end;
   } while(1);
}