Re: Foreign memory context read

Vaibhav Kaushal <vaibhavkaushal123(at)gmail(dot)com> writes:
> My mind started wandering after that error. Now, actually, i was trying to
> do something like this:

> *last_result = palloc0(sizeof(Datum));
> bool *isnnuull = true;
> *last_result = slot_getattr(slot, num_atts, *isnnuull);

This seems utterly confused about data types. The first line thinks
that last_result is of type Datum ** (ie, pointer to pointer to Datum),
since it's storing a pointer-to-Datum through it. The third line
however is treating last_result as of type Datum *, since it's storing
a Datum (not pointer to Datum) through it. And the second line is
assigning "true" (a bool value) to a variable declared as pointer to
bool, which you then proceed to incorrectly dereference while passing it
as the last argument to slot_getattr. The code will certainly crash on
that deref, independently of the multiple other bugs here.

Recommendation: gcc is your friend. Pay attention to the warnings it
gives you.

regards, tom lane