Re: Expanding the use of FLEXIBLE_ARRAY_MEMBER for declarations like foo[1]

Michael Paquier <michael.paquier@gmail.com> writes:
> On Thu, Feb 19, 2015 at 7:29 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Moreover, if we have any code that is assuming such cases are okay, it
>> probably needs a second look.  Isn't this situation effectively assuming
>> that a variable-length array is fixed-length?

> AFAIK, switching a bunch of things to use FLEXIBLE_ARRAY_MEMBER has
> put a couple of things in light that could be revisited:
> 1) tuptoaster.c, with this declaration of varlena:
>         struct
>         {
>                 struct varlena hdr;
>                 char            data[TOAST_MAX_CHUNK_SIZE]; /* make
> struct big enough */
>                 int32           align_it;       /* ensure struct is
> aligned well enough */
>         }                       chunk_data;

I'm pretty sure that thing ought to be a union, not a struct.

> 2) inv_api.c with this thing:
>         struct
>         {
>                 bytea           hdr;
>                 char            data[LOBLKSIZE];        /* make struct
> big enough */
>                 int32           align_it;       /* ensure struct is
> aligned well enough */
>         }                       workbuf;

And probably this too.

> 3) heapam.c in three places with HeapTupleHeaderData:
>         struct
>         {
>                 HeapTupleHeaderData hdr;
>                 char            data[MaxHeapTupleSize];
>         }                       tbuf;

And this, though I'm not sure if we'd have to change the size of the
padding data[] member.

> 5) reorderbuffer.h with its use of HeapTupleHeaderData:

Hmm.  Andres will have to answer for that one ;-)
        regards, tom lane