On Wed, Sep 28, 2011 at 2:49 PM, Andi Kleen <a...@firstfloor.org> wrote:
> From: Andi Kleen <a...@linux.intel.com>
>
> When available use /dev/urandom to get the random seem. This will lower the
> probability
> of collisions.
>
> On other systems it will fallback to the old methods.
>
> Passes bootstrap + testsuite on x86_64. Ok?
>
> gcc/:
>
> * 2011-09-26 Andi Kleen <a...@linux.intel.com>
>
> * toplev.c (init_local_tick): Try reading random seed from /dev/urandom
> ---
> gcc/toplev.c | 12 +++++++++++-
> 1 files changed, 11 insertions(+), 1 deletions(-)
>
> diff --git a/gcc/toplev.c b/gcc/toplev.c
> index 78583fc..ab6b5a4 100644
> --- a/gcc/toplev.c
> +++ b/gcc/toplev.c
> @@ -262,7 +262,17 @@ init_local_tick (void)
> {
> if (!flag_random_seed)
> {
> - /* Get some more or less random data. */
> + /* Try urandom first. Time of day is too likely to collide.
> + In case of any error we just use the local tick. */
> +
> + int fd = open ("/dev/urandom", O_RDONLY);
> + if (fd >= 0)
> + {
> + read (fd, &random_seed, sizeof (random_seed));
I suppose we might get interrupted before anything is read and
read can return with -1 (I suppose partial reads are quite unlikely
though)? Thus, don't we need the usual EINTR loop?
If not, the patch is ok.
Thanks,
Richard.
> + close (fd);
> + }
> +
> + /* Now get the tick anyways */
> #ifdef HAVE_GETTIMEOFDAY
> {
> struct timeval tv;
> --
> 1.7.5.4
>
>
