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

Michael Paquier <michael(dot)paquier(at)gmail(dot)com> writes:
> On Thu, Feb 19, 2015 at 7:29 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)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