Re: can DYNAMIC_ARRAY set its first argument to NULL?

[Bruno H. <br...@cl...>]

Hi Sam,

> Can
> 
> --8<---------------cut here---------------start------------->8---
> DYNAMIC_ARRAY(prompt,char,Sbvector_length(lastline)+1);
> --8<---------------cut here---------------end--------------->8---
> 
> set prompt to NULL?

Yes, this can happen if
  1) we're not doing the allocation on the stack, and
  2) malloca(), based on malloc(), fails - this happens when memory is tight.

> everywhere else we seem to assume that it is non-NULL.

Yuck. This may lead to crashes when memory is so tight that the OS will not
give the process more memory.

If you are going to fix this:
The other - probably bigger - risk is that the allocation will be larger
than the stack. That is, instead of
  arrayeltype arrayvar[arraysize]
or
  arrayeltype* arrayvar = (arrayeltype*)alloca((arraysize)*sizeof(arrayeltype))
- which both the overflow the stack - we should *always* do
  arrayeltype* arrayvar = (arrayeltype*)malloca((arraysize)*sizeof(arrayeltype))
because it puts only small allocations on the stack.

Bruno