std::rand: Add OSRng, ReaderRng wrappers around the OS RNG & generic Readers respectively.

The former reads from e.g. /dev/urandom, the latter just wraps any
std::rt::io::Reader into an interface that implements Rng.

This also adds Rng.fill_bytes for efficient implementations of the above
(reading 8 bytes at a time is inefficient when you can read 1000), and
removes the dependence on src/rt (i.e. rand_gen_seed) although this last
one requires implementing hand-seeding of the XorShiftRng used in the
scheduler on Linux/unixes, since OSRng relies on a scheduler existing to
be able to read from /dev/urandom.

1 files changed, 193 insertions, 0 deletions

diff --git a/src/libstd/rand/os.rs b/src/libstd/rand/os.rs
new file mode 100644
index 00000000000..0e6472b4d37
--- /dev/null
+++ b/src/libstd/rand/os.rs
@@ -0,0 +1,193 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Interfaces to the operating system provided random number
+//! generators.
+
+use rand::Rng;
+use ops::Drop;
+
+#[cfg(unix)]
+use rand::reader::ReaderRng;
+#[cfg(unix)]
+use rt::io::{file, Open, Read};
+
+#[cfg(windows)]
+use ptr;
+#[cfg(windows)]
+use cast;
+#[cfg(windows)]
+use libc::{GetLastError, FALSE};
+
+/// A random number generator that retrieves randomness straight from
+/// the operating system. On Unix-like systems this reads from
+/// `/dev/urandom`, on Windows this uses `CryptGenRandom`.
+///
+/// This does not block.
+#[cfg(unix)]
+pub struct OSRng {
+    priv inner: ReaderRng<file::FileStream>
+}
+/// A random number generator that retrieves randomness straight from
+/// the operating system. On Unix-like systems this reads from
+/// `/dev/urandom`, on Windows this uses `CryptGenRandom`.
+///
+/// This does not block.
+///
+/// XXX: it is unlikely that this is threadsafe with the use of
+/// GetLastError.
+#[cfg(windows)]
+pub struct OSRng {
+    priv hcryptprov: raw::HCRYPTPROV
+}
+
+impl OSRng {
+    /// Create a new `OSRng`.
+    #[cfg(unix)]
+    pub fn new() -> OSRng {
+        let reader = file::open(& &"/dev/urandom", Open, Read).expect("Error opening /dev/urandom");
+        let reader_rng = ReaderRng::new(reader);
+
+        OSRng { inner: reader_rng }
+    }
+
+    /// Create a new `OSRng`.
+    #[cfg(windows)]
+    pub fn new() -> OSRng {
+        let hcp = ptr::mut_null();
+        // TODO these two 0 constants are incorrect!
+        if unsafe { raw::CryptAcquireContext(hcp, ptr::null(), ptr::null(), 0, 0); } == FALSE {
+            fail!("CryptAcquireContext failed with error %u", unsafe {GetLastError()})
+        }
+
+        OSRng { hcryptprov: hcp }
+    }
+}
+
+#[cfg(unix)]
+impl Rng for OSRng {
+    fn next_u32(&mut self) -> u32 {
+        self.inner.next_u32()
+    }
+    fn next_u64(&mut self) -> u64 {
+        self.inner.next_u64()
+    }
+    fn fill_bytes(&mut self, v: &mut [u8]) {
+        self.inner.fill_bytes(v)
+    }
+}
+
+#[cfg(windows)]
+impl Rng for OSRng {
+    fn next_u32(&mut self) -> u32 {
+        let mut v = [0u8, .. 4];
+        self.fill_bytes(v);
+        unsafe { cast::transmute(v) }
+    }
+    fn next_u64(&mut self) -> u64 {
+        let mut v = [0u8, .. 8];
+        self.fill_bytes(v);
+        unsafe { cast::transmute(v) }
+    }
+    fn fill_bytes(&mut self, v: &mut [u8]) {
+        if unsafe { raw::CryptGenRandom(self.hcryptprov, v.len(), v.unsafe_mut_ref(0)) } == FALSE {
+            fail!("CryptGenRandom failed with error %u", unsafe {GetLastError()})
+        }
+    }
+}
+
+impl Drop for OSRng {
+    #[cfg(unix)]
+    fn drop(&mut self) {
+        // ensure that OSRng is not implicitly copyable on all
+        // platforms, for consistency.
+    }
+
+    #[cfg(windows)]
+    fn drop(&mut self) {
+        // TODO this 0 means?
+        if unsafe { raw::CryptReleaseContext(self.hcryptprov, 0)} == FALSE {
+            fail!("CryptReleaseContext failed with error %u", unsafe {GetLastError()})
+        }
+    }
+}
+
+#[abi = "cdecl"]
+#[cfg(windows)]
+mod raw {
+    use libc::{LPCTSTR, DWORD, BOOL, BYTE};
+
+    enum HCRYPTPROV_opaque {}
+    pub type HCRYPTPROV = *CRYPTPROV;
+    extern {
+        pub fn CryptAcquireContext(phProv: *mut HCRYPTPROV,
+                                   pszContainer: LPCTSTR, pszProvider: LPCTSTR,
+                                   dwProvType: DWORD, dwFlags: DWORD) -> BOOL;
+        pub fn CryptGenRandom(hProv: HCRYPTPROV, dwLen: DWORD, pbBuffer: *mut BYTE) -> BOOL;
+        pub fn CryptReleaseContext(hProv: HCRYPTPROV, dwFlags: DWORD) -> BOOL;
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use rand::Rng;
+
+    #[test]
+    fn test_os_rng() {
+        let mut r = OSRng::new();
+
+        r.next_u32();
+        r.next_u64();
+
+        let mut v = [0u8, .. 1000];
+        r.fill_bytes(v);
+    }
+
+    #[test]
+    fn test_os_rng_tasks() {
+        use task;
+        use comm;
+        use comm::{GenericChan, GenericPort};
+        use option::{None, Some};
+        use iter::{Iterator, range};
+        use vec::{ImmutableVector, OwnedVector};
+
+        let mut chans = ~[];
+        for _ in range(0, 20) {
+            let (p, c) = comm::stream();
+            chans.push(c);
+            do task::spawn_with(p) |p| {
+                // wait until all the tasks are ready to go.
+                p.recv();
+
+                // deschedule to attempt to interleave things as much
+                // as possible (XXX: is this a good test?)
+                let mut r = OSRng::new();
+                task::deschedule();
+                let mut v = [0u8, .. 1000];
+
+                for _ in range(0, 100) {
+                    r.next_u32();
+                    task::deschedule();
+                    r.next_u64();
+                    task::deschedule();
+                    r.fill_bytes(v);
+                    task::deschedule();
+                }
+            }
+        }
+
+        // start all the tasks
+        for c in chans.iter() {
+            c.send(())
+        }
+    }
+}