Re: (ITS#8335) MDB_MULTIPLE issues

[hyc@symas.com]

h.b.furuseth@usit.uio.no wrote:
> On 07/12/15 10:14, h.b.furuseth@usit.uio.no wrote:
>> Put(0 data items, MDB_MULTIPLE) stores 1 item.  The doc does
>> not warn against 0 items.  I suggest supporting 0 items, it
>> is a commonly supported convenience elsewhere (e.g. memcpy).
>
> I.e. supporting it as a no-op.  But on second thought I think
> that's misleading and EINVAL is better: If the key doesn't exist,
> this is an attempt to create a key with no data.  Unsupported.
> Bryan Matsuo just posted a test case to openldap-technical.

EINVAL makes sense here.

> datacount > UINT_MAX is truncated to unsigned int:
> data[1].mv_size = 0x100000002 puts 2 items.

> datacount * datasize can exceed UINT_MAX, which mdb_page_spill()
> truncates to unsigned int.  Such a massive put() will likely
> fail anyway, but it should at least try to spill properly first.

We should probably check if mv_size is greater than UINT_MAX and return 
EINVAL. (Or ERANGE.)

>> Why does MDB_MULTIPLE require a cursor? mdb_put() rejects it.

Because get only works with a cursor.

-- 
   -- Howard Chu
   CTO, Symas Corp.           http://www.symas.com
   Director, Highland Sun     http://highlandsun.com/hyc/
   Chief Architect, OpenLDAP  http://www.openldap.org/project/