Re: Implementing getrandom/getentropy, anybody?

[Samuel Thibault]

Andrew Eggenberger, le mar. 29 oct. 2019 00:30:17 -0500, a ecrit:
> Here's a really quick implementation just to get some feedback.

That's already a beginning.

The implementation shouldn't go in the platform-generic stdlib/ files,
but in sysdeps/mach/hurd/

> @@ -24,8 +24,11 @@
>  int
>  getentropy (void *buffer, size_t length)
>  {
> -  __set_errno (ENOSYS);
> -  return -1;
> +  size_t bytes_read;
> +  bytes_read = getrandom(buffer, length, 0);
> +  if (bytes_read != length){

Getrandom is allowed not to return the proper length. Getentropy should
have a loop around it. The ./sysdeps/unix/sysv/linux/getentropy.c
version might actually be used as such.

>  ssize_t
>  getrandom (void *buffer, size_t length, unsigned int flags)
>  {
> -  __set_errno (ENOSYS);
> -  return -1;
> -}
> +  FILE * random_source;
> +  if (flags & GRND_RANDOM){
> +    random_source = fopen("/dev/random", "r");
> +    return fread(buffer, 1, length, random_source);

Rather use open/read, there is no need for buffering. Also remember to
close it. You can factorize the open/read/close calls by only setting a
char* variable in the if.

Samuel