Pointers

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Safe pointers manipulation.

Functions

The sewer library provides macros and functions for "safe" pointers manipulation. By "safe" we mean the fact that the SDK will detect improper pointer access just before a segment violation occurs. Does it make sense to detect a segment violation if the program is going to crash anyway? Pre-detection plays a very important role when running automated tests. Before the inevitable process closing, it will leave a note in the execution log.txt, indicating the reason for the crash.

• Use ptr_get to get the content of a pointer.

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// v2 = NULL // Segmentation fault V2Df v1 = *v2; // "v2 is NULL in file::line" // will be record in log.txt // and then, Segmentation fault V2Df v1 = ptr_get(v2, V2Df);

ptr_get ()

Access to the content of the pointer (dereference), verifying previously that it is not NULL.

void
ptr_get(type *ptr,
        type);

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void compute(const V2Df *v1, const V2Df *v2)
{
    /* Safer than t = *v1; */
    V2Df t = ptr_get(v1, V2Df);
    ...
}

ptr_dget ()

Access the content of a double pointer, invalidating it later.

void
ptr_dget(type **ptr,
         type);

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Ctrl *create(Model **model, View **view)
{
    Ctrl *ctrl = heap_new(Ctrl);
    ctrl->model = ptr_dget(model, Model);
    ctrl->view = ptr_dget(view, View);
    // *model = NULL
    // *view = NULL
    return ctrl;
}

ptr_dget_no_null ()

Like ptr_dget, but the content of the double pointer (*dptr) can not be NULL.

void
ptr_dget_no_null(type **ptr,
                 type);

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Ctrl *create(Model **model, View **view)
{
    // *model and *view can't be NULL
    Ctrl *ctrl = heap_new(Ctrl);
    ctrl->model = ptr_dget_no_null(model, Model);
    ctrl->view = ptr_dget_no_null(view, View);
    return ctrl;
}

ptr_assign ()

Assign content from one pointer to another, if the destination is not NULL.

void
ptr_assign(dest,
           src);

ptr_destopt ()

Destroy an object if not NULL.

void
ptr_destopt(FPtr_destroy func_destroy,
            type dptr,
            type);

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cassert_no_null(dptr);
if (*dptr != NULL)
{
    func_destroy(*dptr);
    *dptr = NULL;
}

ptr_copyopt ()

Copy the object if not NULL.

void
ptr_copyopt(FPtr_copy func_copy,
            type ptr,
            type);

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if (ptr != NULL)
    return func_copy(ptr);
else
    return NULL;