8 Update Solaris getrandom

Author: jasonbking

src/lib.rs

@@ -100,6 +100,7 @@
     target_os = "android",
     target_os = "netbsd",
     target_os = "solaris",
+    target_os = "illumos",
     target_os = "redox",
     target_os = "dragonfly",
     target_os = "haiku",
@@ -138,7 +139,7 @@ mod_use!(cfg(target_os = "macos"), macos);
 mod_use!(cfg(target_os = "netbsd"), netbsd);
 mod_use!(cfg(target_os = "openbsd"), openbsd_bitrig);
 mod_use!(cfg(target_os = "redox"), redox);
-mod_use!(cfg(target_os = "solaris"), solaris);
+mod_use!(cfg(any(target_os = "solaris", target_os = "illumos")), solarish);
 mod_use!(cfg(windows), windows);
 mod_use!(cfg(target_env = "sgx"), sgx);
 
@@ -171,6 +172,7 @@ mod_use!(
         target_os = "freebsd",
         target_os = "fuchsia",
         target_os = "haiku",
+        target_os = "illumos",
         target_os = "ios",
         target_os = "linux",
         target_os = "macos",

src/solaris.rs

@@ -0,0 +1,99 @@
+// Copyright 2018 Developers of the Rand project.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Implementation for the Solaris family
+//!
+//! Read from `/dev/random`, with chunks of limited size (256 bytes).
+//! `/dev/random` uses the Hash_DRBG with SHA512 algorithm from NIST SP 800-90A.
+//! `/dev/urandom` uses the FIPS 186-2 algorithm, which is considered less
+//! secure. We choose to read from `/dev/random`.
+//!
+//! Since Solaris 11.3 and mid-2015 illumos, the `getrandom` syscall is available.
+//! To make sure we can compile on both Solaris and its derivatives, as well as
+//! function, we check for the existance of getrandom(2) in libc by calling
+//! libc::dlsym.
+extern crate libc;
+
+use super::Error;
+use std::cell::RefCell;
+use std::fs::File;
+use std::io;
+use std::io::Read;
+use utils::use_init;
+
+#[cfg(target_os = "illumos")]
+type GetRandomFn = unsafe extern "C" fn(*mut u8, libc::size_t, libc::c_uint) -> libc::ssize_t;
+#[cfg(target_os = "solaris")]
+type GetRandomFn = unsafe extern "C" fn(*mut u8, libc::size_t, libc::c_uint) -> libc::c_int;
+
+enum RngSource {
+    GetRandom(GetRandomFn),
+    Device(File),
+}
+
+thread_local!(
+    static RNG_SOURCE: RefCell<Option<RngSource>> = RefCell::new(None);
+);
+
+fn libc_getrandom(rand: GetRandomFn, dest: &mut [u8]) -> Result<(), Error> {
+    let ret = unsafe { rand(dest.as_mut_ptr(), dest.len(), 0) as libc::ssize_t };
+
+    if ret == -1 || ret != dest.len() as libc::ssize_t {
+        Err(io::Error::last_os_error().into())
+    } else {
+        Ok(())
+    }
+}
+
+pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
+    // 256 bytes is the lowest common denominator across all the Solaris
+    // derived platforms for atomically obtaining random data.
+    RNG_SOURCE.with(|f| {
+        use_init(
+            f,
+            || {
+                let s = match fetch_getrandom() {
+                    Some(fptr) => RngSource::GetRandom(fptr),
+                    None => RngSource::Device(File::open("/dev/random")?),
+                };
+                Ok(s)
+            },
+            |f| {
+                match f {
+                    RngSource::GetRandom(rp) => {
+                        for chunk in dest.chunks_mut(256) {
+                            libc_getrandom(*rp, chunk)?
+                        }
+                    }
+                    RngSource::Device(randf) => {
+                        for chunk in dest.chunks_mut(256) {
+                            randf.read_exact(chunk)?
+                        }
+                    }
+                };
+                Ok(())
+            },
+        )
+    })
+}
+
+fn fetch_getrandom() -> Option<GetRandomFn> {
+    use std::mem;
+    use std::sync::atomic::{AtomicUsize, Ordering};
+
+    static FPTR: AtomicUsize = AtomicUsize::new(1);
+
+    if FPTR.load(Ordering::SeqCst) == 1 {
+        let name = "getrandom\0";
+        let addr = unsafe { libc::dlsym(libc::RTLD_DEFAULT, name.as_ptr() as *const _) as usize };
+        FPTR.store(addr, Ordering::SeqCst);
+    }
+
+    let ptr = FPTR.load(Ordering::SeqCst);
+    unsafe { mem::transmute::<usize, Option<GetRandomFn>>(ptr) }
+}