Re: [PATCH] Refactor malloc (x * sizeof (t) to XNMALLOC (x, t).

[Paul Eggert <eggert at cs dot ucla dot edu>]

On 10/31/2013 09:46 AM, OndÅej BÃlka wrote:

> +#define XNMALLOC(e, tp) (tp *) malloc ((e) * sizeof (tp))

Don't we need something similar for realloc?

It needs another parentheses around the entire definiens.

Better yet, why not a function instead of a macro?
E.g., something like this in libc-internal.h:

  /* Return the address of an array of N objects, each of nonzero
     size S, or NULL (setting errno) if the allocation fails.  */

  inline void *
  nmalloc (size_t n, size_t s)
  {
    return malloc (n <= SIZE_MAX / s ? n * s : SIZE_MAX);
  }

That way, instead of this:

  result = XNMALLOC (step_cnt, struct __gconv_step);

a caller can write this:

  result = nmalloc (step_cnt, sizeof *result);

with simpler semantics, and with less churn later if 'result' changes
its type.