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author | bors <bors@rust-lang.org> | 2019-04-16 16:04:12 +0000 |
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committer | bors <bors@rust-lang.org> | 2019-04-16 16:04:12 +0000 |
commit | 70f130954d6fd36fe3e77f4b5b33e5af50489288 (patch) | |
tree | afcb656d306e236040f00690222892cc627d0992 | |
parent | 3b27b4f592e0654602d8b81cc471204abc2d563e (diff) | |
parent | f1da89a66705a34936a6dbfcd617d8adc76fefd0 (diff) | |
download | rust-70f130954d6fd36fe3e77f4b5b33e5af50489288.tar.gz |
Auto merge of #59879 - ebarnard:patch-1, r=alexcrichton
Add a comment explaining why SecRandomCopyBytes is not used on MacOS
SecRandomCopyBytes is [available since MacOS 10.7](https://developer.apple.com/documentation/security/1399291-secrandomcopybytes?language=objc) which is the minimum supported version and which was suggested in https://github.com/rust-lang/rust/pull/58901#issuecomment-470188115 is the earliest version currently in use.
This matches the behaviour of other platforms which have a random number generator syscall available.
-rw-r--r-- | src/libstd/sys/unix/rand.rs | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/src/libstd/sys/unix/rand.rs b/src/libstd/sys/unix/rand.rs index 122f22b37a2..77f1439e17b 100644 --- a/src/libstd/sys/unix/rand.rs +++ b/src/libstd/sys/unix/rand.rs @@ -99,6 +99,13 @@ mod imp { } } +// On iOS and MacOS `SecRandomCopyBytes` calls `CCRandomCopyBytes` with +// `kCCRandomDefault`. `CCRandomCopyBytes` manages a CSPRNG which is seeded +// from `/dev/random` and which runs on its own thread accessed via GCD. +// This seems needlessly heavyweight for the purposes of generating two u64s +// once per thread in `hashmap_random_keys`. Therefore `SecRandomCopyBytes` is +// only used on iOS where direct access to `/dev/urandom` is blocked by the +// sandbox. #[cfg(target_os = "ios")] mod imp { use crate::io; |