[RFC] [PATCH 2/2] libio: fmemopen rewrite to POSIX compliance

[Rasmus Villemoes]

Adhemerval Zanella <azanella@linux.vnet.ibm.com> writes:

> This patch added a new fmemopen version, for glibc 2.20, that aims to be
> POSIX complaint.

[snip]

>  FILE *
> -fmemopen (void *buf, size_t len, const char *mode)
> +__fmemopen (void *buf, size_t len, const char *mode)
>  {
>    cookie_io_functions_t iof;
>    fmemopen_cookie_t *c;
>  
>    if (__glibc_unlikely (len == 0))
>      {
> -    einval:
>        __set_errno (EINVAL);
>        return NULL;
>      }

Regarding this, note that POSIX is changing [1] to allow, and in the future
maybe even require, fmemopen(s, strlen(s), "r") to work, even if s
happens to be an empty string. IMHO, the only sane semantics for
fmemopen with a length of 0 is to behave like /dev/null (when reading)
and /dev/full (when writing).

[1] http://austingroupbugs.net/view.php?id=818

Rasmus