4 pub fn hashmap_random_keys() -> (u64, u64) {
7 let view = slice::from_raw_parts_mut(&mut v as *mut _ as *mut u8,
15 not(target_os = "ios"),
16 not(all(target_os = "macos", miri)),
17 not(target_os = "openbsd"),
18 not(target_os = "freebsd"),
19 not(target_os = "fuchsia")))]
24 #[cfg(any(target_os = "linux", target_os = "android"))]
25 fn getrandom(buf: &mut [u8]) -> libc::c_long {
27 libc::syscall(libc::SYS_getrandom, buf.as_mut_ptr(), buf.len(), libc::GRND_NONBLOCK)
31 #[cfg(not(any(target_os = "linux", target_os = "android")))]
32 fn getrandom_fill_bytes(_buf: &mut [u8]) -> bool { false }
34 #[cfg(any(target_os = "linux", target_os = "android"))]
35 fn getrandom_fill_bytes(v: &mut [u8]) -> bool {
36 use crate::sync::atomic::{AtomicBool, Ordering};
37 use crate::sys::os::errno;
39 static GETRANDOM_UNAVAILABLE: AtomicBool = AtomicBool::new(false);
40 if GETRANDOM_UNAVAILABLE.load(Ordering::Relaxed) {
45 while read < v.len() {
46 let result = getrandom(&mut v[read..]);
48 let err = errno() as libc::c_int;
49 if err == libc::EINTR {
51 } else if err == libc::ENOSYS {
52 GETRANDOM_UNAVAILABLE.store(true, Ordering::Relaxed);
54 } else if err == libc::EAGAIN {
57 panic!("unexpected getrandom error: {}", err);
60 read += result as usize;
66 pub fn fill_bytes(v: &mut [u8]) {
67 // getrandom_fill_bytes here can fail if getrandom() returns EAGAIN,
68 // meaning it would have blocked because the non-blocking pool (urandom)
69 // has not initialized in the kernel yet due to a lack of entropy. The
70 // fallback we do here is to avoid blocking applications which could
71 // depend on this call without ever knowing they do and don't have a
72 // work around. The PRNG of /dev/urandom will still be used but over a
73 // possibly predictable entropy pool.
74 if getrandom_fill_bytes(v) {
78 // getrandom failed because it is permanently or temporarily (because
79 // of missing entropy) unavailable. Open /dev/urandom, read from it,
80 // and close it again.
81 let mut file = File::open("/dev/urandom").expect("failed to open /dev/urandom");
82 file.read_exact(v).expect("failed to read /dev/urandom")
86 #[cfg(target_os = "openbsd")]
88 use crate::sys::os::errno;
90 pub fn fill_bytes(v: &mut [u8]) {
91 // getentropy(2) permits a maximum buffer size of 256 bytes
92 for s in v.chunks_mut(256) {
94 libc::getentropy(s.as_mut_ptr() as *mut libc::c_void, s.len())
97 panic!("unexpected getentropy error: {}", errno());
103 // On iOS and MacOS `SecRandomCopyBytes` calls `CCRandomCopyBytes` with
104 // `kCCRandomDefault`. `CCRandomCopyBytes` manages a CSPRNG which is seeded
105 // from `/dev/random` and which runs on its own thread accessed via GCD.
106 // This seems needlessly heavyweight for the purposes of generating two u64s
107 // once per thread in `hashmap_random_keys`. Therefore `SecRandomCopyBytes` is
108 // only used on iOS where direct access to `/dev/urandom` is blocked by the
110 // HACK: However, we do use this when running in Miri on macOS; intercepting this is much
111 // easier than intercepting accesses to /dev/urandom.
112 #[cfg(any(target_os = "ios", all(target_os = "macos", miri)))]
116 use libc::{c_int, size_t};
120 #[allow(non_upper_case_globals)]
121 const kSecRandomDefault: *const SecRandom = ptr::null();
124 fn SecRandomCopyBytes(rnd: *const SecRandom,
126 bytes: *mut u8) -> c_int;
129 pub fn fill_bytes(v: &mut [u8]) {
131 SecRandomCopyBytes(kSecRandomDefault,
136 panic!("couldn't generate random bytes: {}",
137 io::Error::last_os_error());
142 #[cfg(target_os = "freebsd")]
146 pub fn fill_bytes(v: &mut [u8]) {
147 let mib = [libc::CTL_KERN, libc::KERN_ARND];
148 // kern.arandom permits a maximum buffer size of 256 bytes
149 for s in v.chunks_mut(256) {
150 let mut s_len = s.len();
152 libc::sysctl(mib.as_ptr(), mib.len() as libc::c_uint,
153 s.as_mut_ptr() as *mut _, &mut s_len,
156 if ret == -1 || s_len != s.len() {
157 panic!("kern.arandom sysctl failed! (returned {}, s.len() {}, oldlenp {})",
158 ret, s.len(), s_len);
164 #[cfg(target_os = "fuchsia")]
166 #[link(name = "zircon")]
168 fn zx_cprng_draw(buffer: *mut u8, len: usize);
171 pub fn fill_bytes(v: &mut [u8]) {
172 unsafe { zx_cprng_draw(v.as_mut_ptr(), v.len()) }