Re: [dpdk-dev] [PATCH v4 2/2] eal: emulate glibc getentropy for initial random seed

[Stephen Hemminger <stephen@networkplumber.org>]

On Wed, 22 Apr 2020 20:42:54 -0300
Dan Gora <dg@adax.com> wrote:

> +	fd = open("/dev/urandom", O_RDONLY);
> +	if (fd < 0) {
> +		errno = ENODEV;
> +		return -1;
> +	}
> +
> +	end = start + length;
> +	while (start < end) {
> +		bytes = read(fd, start, end - start);
> +		if (bytes < 0) {

You are overdoing the complexity here. More error handling is not better.

1. This should only be called once at startup EINTR is not an issue then
2. The amount requested is always returned when using urandom (see man page for random(4))

       The  O_NONBLOCK  flag  has  no effect when opening /dev/urandom.  When calling
       read(2) for the device /dev/urandom, reads of up to 256 bytes will  return  as
       many  bytes  as are requested and will not be interrupted by a signal handler.
       Reads with a buffer over this limit may return less than the requested  number
       of bytes or fail with the error EINTR, if interrupted by a signal handler.