[PATCH] free: preserve errno [BZ#17924]

[Florian Weimer]

* Paul Eggert:

> +/* The indirection through a volatile function pointer is necessary to prevent
> +   a GCC optimization.  Without it, when optimizing, GCC would "know" that errno
> +   is unchanged by calling free(ptr), when ptr was the result of a malloc(...)
> +   call in the same function.  */
> +static int
> +get_errno (void)

Long line (80 characters).

I think you need to use this:

int __attribute__ ((weak))
get_errno (void)
{
  return errno;
}

With that volatile construct, the read of errno is not actually behind a
compiler barrier.

Thanks,
Florian
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