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(target_os = "openbsd"),
17 not(target_os = "freebsd"),
18 not(target_os = "netbsd"),
19 not(target_os = "fuchsia"),
20 not(target_os = "redox")))]
25 #[cfg(any(target_os = "linux", target_os = "android"))]
26 fn getrandom(buf: &mut [u8]) -> libc::c_long {
28 libc::syscall(libc::SYS_getrandom, buf.as_mut_ptr(), buf.len(), libc::GRND_NONBLOCK)
32 #[cfg(not(any(target_os = "linux", target_os = "android")))]
33 fn getrandom_fill_bytes(_buf: &mut [u8]) -> bool { false }
35 #[cfg(any(target_os = "linux", target_os = "android"))]
36 fn getrandom_fill_bytes(v: &mut [u8]) -> bool {
37 use crate::sync::atomic::{AtomicBool, Ordering};
38 use crate::sys::os::errno;
40 static GETRANDOM_UNAVAILABLE: AtomicBool = AtomicBool::new(false);
41 if GETRANDOM_UNAVAILABLE.load(Ordering::Relaxed) {
46 while read < v.len() {
47 let result = getrandom(&mut v[read..]);
49 let err = errno() as libc::c_int;
50 if err == libc::EINTR {
52 } else if err == libc::ENOSYS || err == libc::EPERM {
53 // Fall back to reading /dev/urandom if `getrandom` is not
54 // supported on the current kernel.
56 // Also fall back in case it is disabled by something like
57 // seccomp or inside of virtual machines.
58 GETRANDOM_UNAVAILABLE.store(true, Ordering::Relaxed);
60 } else if err == libc::EAGAIN {
63 panic!("unexpected getrandom error: {}", err);
66 read += result as usize;
72 pub fn fill_bytes(v: &mut [u8]) {
73 // getrandom_fill_bytes here can fail if getrandom() returns EAGAIN,
74 // meaning it would have blocked because the non-blocking pool (urandom)
75 // has not initialized in the kernel yet due to a lack of entropy. The
76 // fallback we do here is to avoid blocking applications which could
77 // depend on this call without ever knowing they do and don't have a
78 // work around. The PRNG of /dev/urandom will still be used but over a
79 // possibly predictable entropy pool.
80 if getrandom_fill_bytes(v) {
84 // getrandom failed because it is permanently or temporarily (because
85 // of missing entropy) unavailable. Open /dev/urandom, read from it,
86 // and close it again.
87 let mut file = File::open("/dev/urandom").expect("failed to open /dev/urandom");
88 file.read_exact(v).expect("failed to read /dev/urandom")
92 #[cfg(target_os = "openbsd")]
94 use crate::sys::os::errno;
96 pub fn fill_bytes(v: &mut [u8]) {
97 // getentropy(2) permits a maximum buffer size of 256 bytes
98 for s in v.chunks_mut(256) {
100 libc::getentropy(s.as_mut_ptr() as *mut libc::c_void, s.len())
103 panic!("unexpected getentropy error: {}", errno());
109 // On iOS and MacOS `SecRandomCopyBytes` calls `CCRandomCopyBytes` with
110 // `kCCRandomDefault`. `CCRandomCopyBytes` manages a CSPRNG which is seeded
111 // from `/dev/random` and which runs on its own thread accessed via GCD.
112 // This seems needlessly heavyweight for the purposes of generating two u64s
113 // once per thread in `hashmap_random_keys`. Therefore `SecRandomCopyBytes` is
114 // only used on iOS where direct access to `/dev/urandom` is blocked by the
116 #[cfg(target_os = "ios")]
120 use libc::{c_int, size_t};
124 #[allow(non_upper_case_globals)]
125 const kSecRandomDefault: *const SecRandom = ptr::null();
128 fn SecRandomCopyBytes(rnd: *const SecRandom,
130 bytes: *mut u8) -> c_int;
133 pub fn fill_bytes(v: &mut [u8]) {
135 SecRandomCopyBytes(kSecRandomDefault,
140 panic!("couldn't generate random bytes: {}",
141 io::Error::last_os_error());
146 #[cfg(any(target_os = "freebsd", target_os = "netbsd"))]
150 pub fn fill_bytes(v: &mut [u8]) {
151 let mib = [libc::CTL_KERN, libc::KERN_ARND];
152 // kern.arandom permits a maximum buffer size of 256 bytes
153 for s in v.chunks_mut(256) {
154 let mut s_len = s.len();
156 libc::sysctl(mib.as_ptr(), mib.len() as libc::c_uint,
157 s.as_mut_ptr() as *mut _, &mut s_len,
160 if ret == -1 || s_len != s.len() {
161 panic!("kern.arandom sysctl failed! (returned {}, s.len() {}, oldlenp {})",
162 ret, s.len(), s_len);
168 #[cfg(target_os = "fuchsia")]
170 #[link(name = "zircon")]
172 fn zx_cprng_draw(buffer: *mut u8, len: usize);
175 pub fn fill_bytes(v: &mut [u8]) {
176 unsafe { zx_cprng_draw(v.as_mut_ptr(), v.len()) }
180 #[cfg(target_os = "redox")]
185 pub fn fill_bytes(v: &mut [u8]) {
186 // Open rand:, read from it, and close it again.
187 let mut file = File::open("rand:").expect("failed to open rand:");
188 file.read_exact(v).expect("failed to read rand:")