[tarantool-patches] Re: [PATCH 6/6] sql: allow to specify UNSIGNED column type
Vladislav Shpilevoy
v.shpilevoy at tarantool.org
Fri Jul 12 00:25:04 MSK 2019
As I promised, below are other comments regarding Mem.u.i/u,
MEM_Int/UInt. Perhaps, they are final.
-------------------------
vdbemem.c:661
> if ((pMem->flags & MEM_Blob) != 0 && type == FIELD_TYPE_NUMBER) {
> bool is_neg;
> if (sql_atoi64(pMem->z, (int64_t *) &pMem->u.i, &is_neg,
> pMem->n) == 0) {
> MemSetTypeFlag(pMem, MEM_Real);
> pMem->u.r = pMem->u.i;
> return 0;
> }
> return ! sqlAtoF(pMem->z, &pMem->u.r, pMem->n);
> }
Here you use assign 'pMem.u.i' to 'pMem.u.r' without checking
its sign. In theory something like that should work wrong now:
box.execute("SELECT CAST('9223372036854775837' AS REAL)")
But you need to somehow write that number as blob.
-------------------------
vdbetrace.c:90
Function sqlVdbeExpandSql stringifies integers, but
misses a version for big unsigned.
-------------------------
vdbe.c:307
> case FIELD_TYPE_INTEGER:
> case FIELD_TYPE_UNSIGNED:
> if ((record->flags & MEM_Int) == MEM_Int)
> return 0;
> if ((record->flags & MEM_UInt) == MEM_UInt)
> return 0;
> if ((record->flags & MEM_Real) == MEM_Real) {
> int64_t i = (int64_t) record->u.r;
> if (i == record->u.r)
> mem_set_int(record, record->u.r,
> record->u.r <= -1);
> return 0;
> }
It is a part of function mem_apply_type. When target type is
UNSIGNED, and a value is MEM_Int, you do nothing. Why? Looks like
it is possible to pass here a negative value, and CAST UNSIGNED
would do nothing.
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