Looping forever?

Hey, while trying to iterate with "next" as a pointer in my structure, it loops forever for no reason, even if i try to make a fake pointer to the structure (not with calling a function to set it up)

my code:

void
command_login(conn,msg)
  void *conn;
  const char *msg;
{
  const char *u,*p;
  char *home;
  ConnectionQueue* q;
  DBResult *result;
  DBResult *tmp;
  bool got_pass,got_user,admin;
  if (!conn)
    return;

  /* initalize */
  q = (ConnectionQueue *)conn;
  got_pass = false; got_user = false; admin = false;
  result = NULL;
  tmp = NULL;
  if (msg == NULL || *msg == '\0'){
    send_socket(q->conn,"LOGIN: Invalid user and password\n");
    return;
  }

  (void)strtok((char *)msg," ");
  u = strtok((char *)NULL, " ");
  p = strtok((char *)NULL, " ");
  if (!u || !p){
    send_socket(q->conn,"LOGIN: Invalid user or pa开发者_StackOverflow社区ssword\n");
    return;
  }

  printf("command_login(): u = %s, p = %s\n",u,p);
  tmp = store_query("SELECT * FROM `users`");
  if (!tmp){
    /* should never happen */
    send_socket(q->conn,"LOGIN: Failed to fetch results\n");
    return;
   }

   printf("command_login(): Checking user and password...\n");
   result = tmp;
  while (result != NULL){
     if (!got_user){
       if (strcmp(result->field_name,"user") == 0 && strcmp(result->field_value,u) == 0)
         got_user = true;
     }else if (!got_pass){
       if (strcmp(result->field_name,"pass") == 0){
          if (strcmp(result->field_value,transform_password(p)) == 0)
            got_pass = true;
       }
     }else if (!admin){
       if (strcmp(result->field_name,"admin") == 0){
         admin = boolean_string(result->field_value);
       }
     }else{
       break;
     }
     result = result->next;
  }

  free_result(result);
  printf("command_login(): Checking got user and got password\n");
  if (!got_user || !got_pass){
    send_socket(q->conn,"LOGIN: Invalid user or password\n");
    return;
  }

  printf("command_login(): Login successfully\n");
  send_socket(q->conn,"LOGIN: Success\n");
  q->conn->state &= ~S_NEED_LOGIN;
  q->admin = admin;
#ifndef _WIN32
  home = getenv("HOME");
#else
  home = getenv("HOMEPATH");
#endif
  if (!home)
    return;

  if (!chdir(home)){
    send_socket(q->conn,"LOGIN: Failed to change to user home directory %s: %s\n",home,strerror(errno));
    close_connection(q->conn);
    return;
   }
   send_socket(q->conn,"CWD: %s\n",home);
}

it loops forever here:

  while (result != NULL){
     if (!got_user){
       if (strcmp(result->field_name,"user") == 0 && strcmp(result->field_value,u) == 0)
         got_user = true;
     }else if (!got_pass){
       if (strcmp(result->field_name,"pass") == 0){
          if (strcmp(result->field_value,transform_password(p)) == 0)
            got_pass = true;
       }
     }else if (!admin){
       if (strcmp(result->field_name,"admin") == 0){
         admin = boolean_string(result->field_value);
       }
     }else{
       break;
     }
     result = result->next;
  }

any ideas? thanks

When you create a new DBResult structure, do you set the next pointer to NULL? If you create the structure with malloc, your test for result would never end.

It's really difficult to know more without knowing the definition of DBResult and the definition of store_query. What does store_query return?

You say you are making a list. In store_query you don't actually set next of ret to tmp. I assume that is what you want to do. Look carefully at your list construction because it is not correct.

It might help to draw a picture of your DBResult as it gets constructed.

Okay, so what you're doing is

ret->next = tmp;
ret = tmp;
ret->next = tmp; // = ret

So you're making a circular linked list with one element. What you need to do is allocate a new element each time you add one. Then remember to free them all at the end.

edit

The pattern should look like this

DBResult* head = NULL;
DBResult* row = NULL;

while(have_rows()) {
    row = malloc(sizeof(DBResult));
    // load row into row

    row->next = head;
    head = row;
}

return head;

// later when you're all done
while(head) {
    DBResult* element = head;
    head = head->next;
    free(element);
}