os.rs.html -- source
Description: Source to the Rust file `C:\Users\Gray\.cargo\registry\src\github.com-1ecc6299db9ec823\rand-0.3.18\src\os.rs`.
Keywords: rust, rustlang, rust-lang

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    // Copyright 2013-2015 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 std::{io, mem, fmt};
    use Rng;

    /// A random number generator that retrieves randomness straight from
    /// the operating system. Platform sources:
    ///
    /// - Unix-like systems (Linux, Android, Mac OSX): read directly from
    ///   `/dev/urandom`, or from `getrandom(2)` system call if available.
    /// - OpenBSD: calls `getentropy(2)`
    /// - FreeBSD: uses the `kern.arandom` `sysctl(2)` mib
    /// - Windows: calls `RtlGenRandom`, exported from `advapi32.dll` as
    ///   `SystemFunction036`.
    /// - iOS: calls SecRandomCopyBytes as /dev/(u)random is sandboxed.
    /// - PNaCl: calls into the `nacl-irt-random-0.1` IRT interface.
    ///
    /// This usually does not block. On some systems (e.g. FreeBSD, OpenBSD,
    /// Max OS X, and modern Linux) this may block very early in the init
    /// process, if the CSPRNG has not been seeded yet.[1]
    ///
    /// [1] See <https://www.python.org/dev/peps/pep-0524/> for a more
    ///     in-depth discussion.
    pub struct OsRng(imp::OsRng);

    impl OsRng {
        /// Create a new `OsRng`.
        pub fn new() -> io::Result<OsRng> {
            imp::OsRng::new().map(OsRng)
        }
    }

    impl Rng for OsRng {
        fn next_u32(&mut self) -> u32 { self.0.next_u32() }
        fn next_u64(&mut self) -> u64 { self.0.next_u64() }
        fn fill_bytes(&mut self, v: &mut [u8]) { self.0.fill_bytes(v) }
    }

    impl fmt::Debug for OsRng {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            write!(f, "OsRng {{}}")
        }
    }

    fn next_u32(mut fill_buf: &mut FnMut(&mut [u8])) -> u32 {
        let mut buf: [u8; 4] = [0; 4];
        fill_buf(&mut buf);
        unsafe { mem::transmute::<[u8; 4], u32>(buf) }
    }

    fn next_u64(mut fill_buf: &mut FnMut(&mut [u8])) -> u64 {
        let mut buf: [u8; 8] = [0; 8];
        fill_buf(&mut buf);
        unsafe { mem::transmute::<[u8; 8], u64>(buf) }
    }

    #[cfg(all(unix, not(target_os = "ios"),
              not(target_os = "nacl"),
              not(target_os = "freebsd"),
              not(target_os = "fuchsia"),
              not(target_os = "openbsd"),
              not(target_os = "redox")))]
    mod imp {
        extern crate libc;

        use super::{next_u32, next_u64};
        use self::OsRngInner::*;

        use std::io;
        use std::fs::File;
        use Rng;
        use read::ReadRng;

        #[cfg(all(target_os = "linux",
                  any(target_arch = "x86_64",
                      target_arch = "x86",
                      target_arch = "arm",
                      target_arch = "aarch64",
                      target_arch = "powerpc")))]
        fn getrandom(buf: &mut [u8]) -> libc::c_long {
            extern "C" {
                fn syscall(number: libc::c_long, ...) -> libc::c_long;
            }

            #[cfg(target_arch = "x86_64")]
            const NR_GETRANDOM: libc::c_long = 318;
            #[cfg(target_arch = "x86")]
            const NR_GETRANDOM: libc::c_long = 355;
            #[cfg(target_arch = "arm")]
            const NR_GETRANDOM: libc::c_long = 384;
            #[cfg(target_arch = "aarch64")]
            const NR_GETRANDOM: libc::c_long = 278;
            #[cfg(target_arch = "powerpc")]
            const NR_GETRANDOM: libc::c_long = 384;

            unsafe {
                syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), 0)
            }
        }

        #[cfg(not(all(target_os = "linux",
                      any(target_arch = "x86_64",
                          target_arch = "x86",
                          target_arch = "arm",
                          target_arch = "aarch64",
                          target_arch = "powerpc"))))]
        fn getrandom(_buf: &mut [u8]) -> libc::c_long { -1 }

        fn getrandom_fill_bytes(v: &mut [u8]) {
            let mut read = 0;
            let len = v.len();
            while read < len {
                let result = getrandom(&mut v[read..]);
                if result == -1 {
                    let err = io::Error::last_os_error();
                    if err.kind() == io::ErrorKind::Interrupted {
                        continue
                    } else {
                        panic!("unexpected getrandom error: {}", err);
                    }
                } else {
                    read += result as usize;
                }
            }
        }

        #[cfg(all(target_os = "linux",
                  any(target_arch = "x86_64",
                      target_arch = "x86",
                      target_arch = "arm",
                      target_arch = "aarch64",
                      target_arch = "powerpc")))]
        fn is_getrandom_available() -> bool {
            use std::sync::atomic::{AtomicBool, ATOMIC_BOOL_INIT, Ordering};
            use std::sync::{Once, ONCE_INIT};

            static CHECKER: Once = ONCE_INIT;
            static AVAILABLE: AtomicBool = ATOMIC_BOOL_INIT;

            CHECKER.call_once(|| {
                let mut buf: [u8; 0] = [];
                let result = getrandom(&mut buf);
                let available = if result == -1 {
                    let err = io::Error::last_os_error().raw_os_error();
                    err != Some(libc::ENOSYS)
                } else {
                    true
                };
                AVAILABLE.store(available, Ordering::Relaxed);
            });

            AVAILABLE.load(Ordering::Relaxed)
        }

        #[cfg(not(all(target_os = "linux",
                      any(target_arch = "x86_64",
                          target_arch = "x86",
                          target_arch = "arm",
                          target_arch = "aarch64",
                          target_arch = "powerpc"))))]
        fn is_getrandom_available() -> bool { false }

        pub struct OsRng {
            inner: OsRngInner,
        }

        enum OsRngInner {
            OsGetrandomRng,
            OsReadRng(ReadRng<File>),
        }

        impl OsRng {
            pub fn new() -> io::Result<OsRng> {
                if is_getrandom_available() {
                    return Ok(OsRng { inner: OsGetrandomRng });
                }

                let reader = try!(File::open("/dev/urandom"));
                let reader_rng = ReadRng::new(reader);

                Ok(OsRng { inner: OsReadRng(reader_rng) })
            }
        }

        impl Rng for OsRng {
            fn next_u32(&mut self) -> u32 {
                match self.inner {
                    OsGetrandomRng => next_u32(&mut getrandom_fill_bytes),
                    OsReadRng(ref mut rng) => rng.next_u32(),
                }
            }
            fn next_u64(&mut self) -> u64 {
                match self.inner {
                    OsGetrandomRng => next_u64(&mut getrandom_fill_bytes),
                    OsReadRng(ref mut rng) => rng.next_u64(),
                }
            }
            fn fill_bytes(&mut self, v: &mut [u8]) {
                match self.inner {
                    OsGetrandomRng => getrandom_fill_bytes(v),
                    OsReadRng(ref mut rng) => rng.fill_bytes(v)
                }
            }
        }
    }

    #[cfg(target_os = "ios")]
    mod imp {
        extern crate libc;

        use super::{next_u32, next_u64};

        use std::io;
        use Rng;
        use self::libc::{c_int, size_t};

        #[derive(Debug)]
        pub struct OsRng;

        enum SecRandom {}

        #[allow(non_upper_case_globals)]
        const kSecRandomDefault: *const SecRandom = 0 as *const SecRandom;

        #[link(name = "Security", kind = "framework")]
        extern {
            fn SecRandomCopyBytes(rnd: *const SecRandom,
                                  count: size_t, bytes: *mut u8) -> c_int;
        }

        impl OsRng {
            pub fn new() -> io::Result<OsRng> {
                Ok(OsRng)
            }
        }

        impl Rng for OsRng {
            fn next_u32(&mut self) -> u32 {
                next_u32(&mut |v| self.fill_bytes(v))
            }
            fn next_u64(&mut self) -> u64 {
                next_u64(&mut |v| self.fill_bytes(v))
            }
            fn fill_bytes(&mut self, v: &mut [u8]) {
                let ret = unsafe {
                    SecRandomCopyBytes(kSecRandomDefault, v.len() as size_t, v.as_mut_ptr())
                };
                if ret == -1 {
                    panic!("couldn't generate random bytes: {}", io::Error::last_os_error());
                }
            }
        }
    }

    #[cfg(target_os = "freebsd")]
    mod imp {
        extern crate libc;

        use std::{io, ptr};
        use Rng;

        use super::{next_u32, next_u64};

        #[derive(Debug)]
        pub struct OsRng;

        impl OsRng {
            pub fn new() -> io::Result<OsRng> {
                Ok(OsRng)
            }
        }

        impl Rng for OsRng {
            fn next_u32(&mut self) -> u32 {
                next_u32(&mut |v| self.fill_bytes(v))
            }
            fn next_u64(&mut self) -> u64 {
                next_u64(&mut |v| self.fill_bytes(v))
            }
            fn fill_bytes(&mut self, v: &mut [u8]) {
                let mib = [libc::CTL_KERN, libc::KERN_ARND];
                // kern.arandom permits a maximum buffer size of 256 bytes
                for s in v.chunks_mut(256) {
                    let mut s_len = s.len();
                    let ret = unsafe {
                        libc::sysctl(mib.as_ptr(), mib.len() as libc::c_uint,
                                     s.as_mut_ptr() as *mut _, &mut s_len,
                                     ptr::null(), 0)
                    };
                    if ret == -1 || s_len != s.len() {
                        panic!("kern.arandom sysctl failed! (returned {}, s.len() {}, oldlenp {})",
                               ret, s.len(), s_len);
                    }
                }
            }
        }
    }

    #[cfg(target_os = "openbsd")]
    mod imp {
        extern crate libc;

        use std::io;
        use Rng;

        use super::{next_u32, next_u64};

        #[derive(Debug)]
        pub struct OsRng;

        impl OsRng {
            pub fn new() -> io::Result<OsRng> {
                Ok(OsRng)
            }
        }

        impl Rng for OsRng {
            fn next_u32(&mut self) -> u32 {
                next_u32(&mut |v| self.fill_bytes(v))
            }
            fn next_u64(&mut self) -> u64 {
                next_u64(&mut |v| self.fill_bytes(v))
            }
            fn fill_bytes(&mut self, v: &mut [u8]) {
                // getentropy(2) permits a maximum buffer size of 256 bytes
                for s in v.chunks_mut(256) {
                    let ret = unsafe {
                        libc::getentropy(s.as_mut_ptr() as *mut libc::c_void, s.len())
                    };
                    if ret == -1 {
                        let err = io::Error::last_os_error();
                        panic!("getentropy failed: {}", err);
                    }
                }
            }
        }
    }

    #[cfg(target_os = "redox")]
    mod imp {
        use std::io;
        use std::fs::File;
        use Rng;
        use read::ReadRng;

        #[derive(Debug)]
        pub struct OsRng {
            inner: ReadRng<File>,
        }

        impl OsRng {
            pub fn new() -> io::Result<OsRng> {
                let reader = try!(File::open("rand:"));
                let reader_rng = ReadRng::new(reader);

                Ok(OsRng { inner: reader_rng })
            }
        }

        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(target_os = "fuchsia")]
    mod imp {
        extern crate fuchsia_zircon;

        use std::io;
        use Rng;

        use super::{next_u32, next_u64};

        #[derive(Debug)]
        pub struct OsRng;

        impl OsRng {
            pub fn new() -> io::Result<OsRng> {
                Ok(OsRng)
            }
        }

        impl Rng for OsRng {
            fn next_u32(&mut self) -> u32 {
                next_u32(&mut |v| self.fill_bytes(v))
            }
            fn next_u64(&mut self) -> u64 {
                next_u64(&mut |v| self.fill_bytes(v))
            }
            fn fill_bytes(&mut self, v: &mut [u8]) {
                for s in v.chunks_mut(fuchsia_zircon::ZX_CPRNG_DRAW_MAX_LEN) {
                    let mut filled = 0;
                    while filled < s.len() {
                        match fuchsia_zircon::cprng_draw(&mut s[filled..]) {
                            Ok(actual) => filled += actual,
                            Err(e) => panic!("cprng_draw failed: {:?}", e),
                        };
                    }
                }
            }
        }
    }

    #[cfg(windows)]
    mod imp {
        use std::io;
        use Rng;

        use super::{next_u32, next_u64};

        type BOOLEAN = u8;
        type ULONG = u32;

        #[link(name = "advapi32")]
        extern "system" {
            // This function's real name is `RtlGenRandom`.
            fn SystemFunction036(RandomBuffer: *mut u8, RandomBufferLength: ULONG) -> BOOLEAN;
        }

        #[derive(Debug)]
        pub struct OsRng;

        impl OsRng {
            pub fn new() -> io::Result<OsRng> {
                Ok(OsRng)
            }
        }

        impl Rng for OsRng {
            fn next_u32(&mut self) -> u32 {
                next_u32(&mut |v| self.fill_bytes(v))
            }
            fn next_u64(&mut self) -> u64 {
                next_u64(&mut |v| self.fill_bytes(v))
            }
            fn fill_bytes(&mut self, v: &mut [u8]) {
                // RtlGenRandom takes an ULONG (u32) for the length so we need to
                // split up the buffer.
                for slice in v.chunks_mut(<ULONG>::max_value() as usize) {
                    let ret = unsafe {
                        SystemFunction036(slice.as_mut_ptr(), slice.len() as ULONG)
                    };
                    if ret == 0 {
                        panic!("couldn't generate random bytes: {}",
                               io::Error::last_os_error());
                    }
                }
            }
        }
    }

    #[cfg(target_os = "nacl")]
    mod imp {
        extern crate libc;

        use std::io;
        use std::mem;
        use Rng;

        use super::{next_u32, next_u64};

        #[derive(Debug)]
        pub struct OsRng(extern fn(dest: *mut libc::c_void,
                                   bytes: libc::size_t,
                                   read: *mut libc::size_t) -> libc::c_int);

        extern {
            fn nacl_interface_query(name: *const libc::c_char,
                                    table: *mut libc::c_void,
                                    table_size: libc::size_t) -> libc::size_t;
        }

        const INTERFACE: &'static [u8] = b"nacl-irt-random-0.1\0";

        #[repr(C)]
        struct NaClIRTRandom {
            get_random_bytes: Option<extern fn(dest: *mut libc::c_void,
                                               bytes: libc::size_t,
                                               read: *mut libc::size_t) -> libc::c_int>,
        }

        impl OsRng {
            pub fn new() -> io::Result<OsRng> {
                let mut iface = NaClIRTRandom {
                    get_random_bytes: None,
                };
                let result = unsafe {
                    nacl_interface_query(INTERFACE.as_ptr() as *const _,
                                         mem::transmute(&mut iface),
                                         mem::size_of::<NaClIRTRandom>() as libc::size_t)
                };
                if result != 0 {
                    assert!(iface.get_random_bytes.is_some());
                    let result = OsRng(iface.get_random_bytes.take().unwrap());
                    Ok(result)
                } else {
                    let error = io::ErrorKind::NotFound;
                    let error = io::Error::new(error, "IRT random interface missing");
                    Err(error)
                }
            }
        }

        impl Rng for OsRng {
            fn next_u32(&mut self) -> u32 {
                next_u32(&mut |v| self.fill_bytes(v))
            }
            fn next_u64(&mut self) -> u64 {
                next_u64(&mut |v| self.fill_bytes(v))
            }
            fn fill_bytes(&mut self, v: &mut [u8]) {
                let mut read = 0;
                loop {
                    let mut r: libc::size_t = 0;
                    let len = v.len();
                    let error = (self.0)(v[read..].as_mut_ptr() as *mut _,
                                         (len - read) as libc::size_t,
                                         &mut r as *mut _);
                    assert!(error == 0, "`get_random_bytes` failed!");
                    read += r as usize;

                    if read >= v.len() { break; }
                }
            }
        }
    }

    #[cfg(test)]
    mod test {
        use std::sync::mpsc::channel;
        use Rng;
        use OsRng;
        use std::thread;

        #[test]
        fn test_os_rng() {
            let mut r = OsRng::new().unwrap();

            r.next_u32();
            r.next_u64();

            let mut v = [0u8; 1000];
            r.fill_bytes(&mut v);
        }

        #[test]
        fn test_os_rng_tasks() {

            let mut txs = vec!();
            for _ in 0..20 {
                let (tx, rx) = channel();
                txs.push(tx);

                thread::spawn(move|| {
                    // wait until all the tasks are ready to go.
                    rx.recv().unwrap();

                    // deschedule to attempt to interleave things as much
                    // as possible (XXX: is this a good test?)
                    let mut r = OsRng::new().unwrap();
                    thread::yield_now();
                    let mut v = [0u8; 1000];

                    for _ in 0..100 {
                        r.next_u32();
                        thread::yield_now();
                        r.next_u64();
                        thread::yield_now();
                        r.fill_bytes(&mut v);
                        thread::yield_now();
                    }
                });
            }

            // start all the tasks
            for tx in txs.iter() {
                tx.send(()).unwrap();
            }
        }
    }

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