Transfer ownership of storage in Splint

问题:

Using a simple linked list implementation in C, how do I tell Splint that I am transfer ownership of data?

typedef struct {
    void* data;
    /*@null@*/ void* next;
} list;

static /*@null@*/ list* new_list(/*@notnull@*/ void* data)
{
    list* l;

    l = malloc(sizeof(list));

    if (l == NULL)
        return NULL;

    l->next = NULL;
    l->data = data;

    return l;
}

I get this error message:

Implicitly temp storage data assigned to implicitly
                             only: list->data = data
  Temp storage (associated with a formal parameter) is transferred to a
  non-temporary reference. The storage may be released or new aliases created.
  (Use -temptrans to inhibit warning)

I want to tell Splint that responsibility of freeing data is transfered to the list data-structure.

回答1:

The solution is in the Splint manual for function interfaces. Basically, change the function signature to this:

static /*@null@*/ list* new_list(/*@notnull@*/ /*@only@*/ void* data)
    /*@defines result->data @*/

Although we'll get a new error when doing this:

int main()
{
    list* l = new_list("hej");

    return 0;
}


 Observer storage passed as only param:
                              new_list ("hej")
  Observer storage is transferred to a non-observer reference. (Use
  -observertrans to inhibit warning)