Re: Implementing getrandom/getentropy, anybody?

[Guillem Jover]

Hi!

On Tue, 2019-10-29 at 23:28:26 -0500, Andrew Eggenberger wrote:
> --- /dev/null
> +++ b/sysdeps/mach/hurd/getrandom.c

> +/* Write up to LENGTH bytes of randomness starting at BUFFER.
> +   Return the number of bytes written, or -1 on error.  */
> +ssize_t
> +getrandom (void *buffer, size_t length, unsigned int flags)
> +{
> +  char* random_source = "/dev/urandom";
> +  int amount_read, fp;

I'd define amount_read as ssize_t. I'd probably call this fd, fp is
usually associated with a «FILE *». Shouldn't the * be next to the
variable instead of the type?

> +  if (flags & GRND_RANDOM){
> +    random_source = "/dev/random";
> +  }
> +
> +  fp = open(random_source, O_RDONLY);

Shouldn't this be opened with O_CLOEXEC, otherwise children created
by other threads might leak file descriptors. Although I don't see
this being consistently done in glibc, not sure why?

> +  amount_read = read(fp, buffer, length);

What about partial reads?

> +  close(fp);
> +  return amount_read;
> +}

Thanks,
Guillem