Add GNU/Hurd support

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

Author: sthibaul

src/lib.rs

@@ -25,6 +25,7 @@
 //! | Redox             | `*‑redox`          | `/dev/urandom`
 //! | Haiku             | `*‑haiku`          | `/dev/urandom` (identical to `/dev/random`)
 //! | Hermit            | `*-hermit`         | [`sys_read_entropy`]
+//! | Hurd              | `*-hurd-*`         | `/dev/urandom`
 //! | SGX               | `x86_64‑*‑sgx`     | [`RDRAND`]
 //! | VxWorks           | `*‑wrs‑vxworks‑*`  | `randABytes` after checking entropy pool initialization with `randSecure`
 //! | ESP-IDF           | `*‑espidf`         | [`esp_fill_random`]
@@ -216,7 +217,7 @@ pub use crate::error::Error;
 // The function MUST NOT ever write uninitialized bytes into `dest`,
 // regardless of what value it returns.
 cfg_if! {
-    if #[cfg(any(target_os = "haiku", target_os = "redox", target_os = "nto", target_os = "aix"))] {
+    if #[cfg(any(target_os = "haiku", target_os = "hurd", target_os = "redox", target_os = "nto", target_os = "aix"))] {
         mod util_libc;
         #[path = "use_file.rs"] mod imp;
     } else if #[cfg(any(target_os = "android", target_os = "linux"))] {

src/use_file.rs

@@ -31,6 +31,7 @@ const FILE_PATH: &str = "/dev/random\0";
     target_os = "redox",
     target_os = "dragonfly",
     target_os = "haiku",
+    target_os = "hurd",
     target_os = "macos",
     target_os = "nto",
 ))]

src/util_libc.rs

@@ -19,7 +19,7 @@ use libc::c_void;
 cfg_if! {
     if #[cfg(any(target_os = "netbsd", target_os = "openbsd", target_os = "android"))] {
         use libc::__errno as errno_location;
-    } else if #[cfg(any(target_os = "linux", target_os = "emscripten", target_os = "redox"))] {
+    } else if #[cfg(any(target_os = "linux", target_os = "emscripten", target_os = "hurd", target_os = "redox"))] {
         use libc::__errno_location as errno_location;
     } else if #[cfg(any(target_os = "solaris", target_os = "illumos"))] {
         use libc::___errno as errno_location;