Re: [PATCH v2 1/4] sha1sum: use AF_ALG when available

[Paul Eggert]

On 04/26/2018 09:02 AM, Matteo Croce wrote:
> I assume that C99 is safe to use in gnulib, good to know

Yes. Until recently we did require C89 in Gnulib because Awk still 
wanted C89. However, that last holdout has finally given up the ghost so 
C99isms are OK if they are portable in practice. I noticed some other 
C99isms in your patch so I assumed you didn't mind C99 either.

> I can't find a definition for S_TYPEISTMO in my compiler
> headers (gcc 7.3.1). Is it for a typed memory object?
> Anyway, the size must be known in advance to use sendfile, is the cas
> for SHM and STMO?

Yes, S_TYPEISTMO is defined by POSIX and st_size is required to work for 
it too. See 
<http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_stat.h.html>. 
It's not in GNU/Linux (it's intended for real-time use which is not 
Linux's forte; a quick Google search suggests that it is supported by 
QNX) but presumably it would work if added, and in the meantime Gnulib 
defines a substitute S_TYPEISTMO that is always zero so your code should 
compile and run the same as if you didn't use it.