Paul Eggert cc98a5e2fd xmalloca, etc.: fix some xalloc-oversized issues ...

* lib/malloca.h (nmalloca):
* lib/xmalloca.h (xnmalloca): Convert S to ptrdiff_t to avoid
arithmetic overflow if N and S are both narrower than ptrdiff_t.
* lib/xalloc-oversized.h (xalloc_oversized):
Don’t say that args must be ptrdiff_t or size_t or wider.
The macro returns the correct answer even when that is not
the case, and it’s the caller’s responsibility to avoid
howlers like (xalloc_oversized (n, s) ? NULL : malloc (n * s))
when N and S are both narrower than ptrdiff_t and size_t.
Add a comment to that effect.
* lib/xmalloca.h: Include xalloc-oversized.h, since this file uses
xalloc_oversized.  Add comments about side effects and avoid
unnecessary parens.
* modules/xmalloca (Depends-on): Add xalloc-oversized.

2021-04-24 18:00:47 -07:00

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