On Fri, Aug 3, 2018 at 4:28 PM, Jakub Jelinek <[email protected]> wrote:
> On Fri, Aug 03, 2018 at 04:19:03PM +0300, Janne Blomqvist wrote:
> > --- a/libgfortran/intrinsics/random.c
> > +++ b/libgfortran/intrinsics/random.c
> > @@ -309,12 +309,9 @@ getosrandom (void *buf, size_t buflen)
> > for (size_t i = 0; i < buflen / sizeof (unsigned int); i++)
> > rand_s (&b[i]);
> > return buflen;
> > +#elif defined(HAVE_GETENTROPY)
> > + return getentropy (buf, buflen);
> > #else
>
> I wonder if it wouldn't be better to use getentropy only if it is
> successful
> and fall back to whatever you were doing before.
>
> E.g. on Linux, I believe getentropy in glibc just uses the getrandom
> syscall, which has only been introduced in Linux kernel 3.17.
>
Yes, that is my understanding as well.
> So, if somebody is running glibc 2.25 or later on kernel < 3.17, it will
> fail, even though reads from /dev/urandom could work.
>
Hmm, fair enough. So replace the random.c part of the patch with
diff --git a/libgfortran/intrinsics/random.c
b/libgfortran/intrinsics/random.c
index 234c5ff95fd..229fa6995c0 100644
--- a/libgfortran/intrinsics/random.c
+++ b/libgfortran/intrinsics/random.c
@@ -310,11 +310,10 @@ getosrandom (void *buf, size_t buflen)
rand_s (&b[i]);
return buflen;
#else
- /*
- TODO: When glibc adds a wrapper for the getrandom() system call
- on Linux, one could use that.
-
- TODO: One could use getentropy() on OpenBSD. */
+#ifdef HAVE_GETENTROPY
+ if (getentropy (buf, buflen) == 0)
+ return 0;
+#endif
int flags = O_RDONLY;
#ifdef O_CLOEXEC
flags |= O_CLOEXEC;
Just to be sure, I regtested this slightly modified patch as well. Ok for
trunk?
--
Janne Blomqvist
