auto merge of #13115 : huonw/rust/rand-errors, r=alexcrichton

move errno -> IoError converter into std, bubble up OSRng errors

Also adds a general errno -> `~str` converter to `std::os`, and makes the failure messages for the things using `OSRng` (e.g. (transitively) the task-local RNG, meaning hashmap initialisation failures aren't such a black box).

1 files changed, 6 insertions, 1 deletions

diff --git a/src/libgreen/sched.rs b/src/libgreen/sched.rs
index adfd5908de2..683df846d62 100644
--- a/src/libgreen/sched.rs
+++ b/src/libgreen/sched.rs
@@ -967,7 +967,12 @@ impl ClosureConverter for UnsafeTaskReceiver {
 // worry there.
 #[cfg(windows)]
 fn new_sched_rng() -> XorShiftRng {
-    XorShiftRng::new()
+    match XorShiftRng::new() {
+        Ok(r) => r,
+        Err(e) => {
+            rtabort!("sched: failed to create seeded RNG: {}", e)
+        }
+    }
 }
 #[cfg(unix)]
 fn new_sched_rng() -> XorShiftRng {