1 //! Platform-independent platform abstraction
3 //! This is the platform-independent portion of the standard library's
4 //! platform abstraction layer, whereas `std::sys` is the
5 //! platform-specific portion.
7 //! The relationship between `std::sys_common`, `std::sys` and the
8 //! rest of `std` is complex, with dependencies going in all
9 //! directions: `std` depending on `sys_common`, `sys_common`
10 //! depending on `sys`, and `sys` depending on `sys_common` and `std`.
11 //! Ideally `sys_common` would be split into two and the dependencies
12 //! between them all would form a dag, facilitating the extraction of
13 //! `std::sys` from the standard library.
15 #![allow(missing_docs)]
16 #![allow(missing_debug_implementations)]
18 use crate::sync::Once;
21 macro_rules! rtabort {
22 ($($t:tt)*) => (crate::sys_common::util::abort(format_args!($($t)*)))
25 macro_rules! rtassert {
28 rtabort!(concat!("assertion failed: ", stringify!($e)));
33 #[allow(unused_macros)] // not used on all platforms
34 macro_rules! rtunwrap {
35 ($ok:ident, $e:expr) => {
39 let err = err.as_ref().map(drop); // map Ok/Some which might not be Debug
40 rtabort!(concat!("unwrap failed: ", stringify!($e), " = {:?}"), err)
54 #[cfg(any(doc, // see `mod os`, docs are generated for multiple platforms
57 target_os = "cloudabi",
59 target_arch = "wasm32",
60 all(target_vendor = "fortanix", target_env = "sgx")))]
73 if #[cfg(any(target_os = "cloudabi",
76 all(target_arch = "wasm32", not(target_os = "emscripten")),
77 all(target_vendor = "fortanix", target_env = "sgx")))] {
78 pub use crate::sys::net;
84 // common error constructors
86 /// A trait for viewing representations from std types
88 pub trait AsInner<Inner: ?Sized> {
89 fn as_inner(&self) -> &Inner;
92 /// A trait for viewing representations from std types
94 pub trait AsInnerMut<Inner: ?Sized> {
95 fn as_inner_mut(&mut self) -> &mut Inner;
98 /// A trait for extracting representations from std types
100 pub trait IntoInner<Inner> {
101 fn into_inner(self) -> Inner;
104 /// A trait for creating std types from internal representations
106 pub trait FromInner<Inner> {
107 fn from_inner(inner: Inner) -> Self;
110 /// Enqueues a procedure to run when the main thread exits.
112 /// Currently these closures are only run once the main *Rust* thread exits.
113 /// Once the `at_exit` handlers begin running, more may be enqueued, but not
114 /// infinitely so. Eventually a handler registration will be forced to fail.
116 /// Returns `Ok` if the handler was successfully registered, meaning that the
117 /// closure will be run once the main thread exits. Returns `Err` to indicate
118 /// that the closure could not be registered, meaning that it is not scheduled
120 pub fn at_exit<F: FnOnce() + Send + 'static>(f: F) -> Result<(), ()> {
121 if at_exit_imp::push(Box::new(f)) { Ok(()) } else { Err(()) }
124 /// One-time runtime cleanup.
126 static CLEANUP: Once = Once::new();
127 CLEANUP.call_once(|| unsafe {
128 sys::args::cleanup();
129 sys::stack_overflow::cleanup();
130 at_exit_imp::cleanup();
134 // Computes (value*numer)/denom without overflow, as long as both
135 // (numer*denom) and the overall result fit into i64 (which is the case
136 // for our time conversions).
137 #[allow(dead_code)] // not used on all platforms
138 pub fn mul_div_u64(value: u64, numer: u64, denom: u64) -> u64 {
139 let q = value / denom;
140 let r = value % denom;
141 // Decompose value as (value/denom*denom + value%denom),
142 // substitute into (value*numer)/denom and simplify.
143 // r < denom, so (denom*numer) is the upper bound of (r*numer)
144 q * numer + r * numer / denom
149 assert_eq!(mul_div_u64(1_000_000_000_001, 1_000_000_000, 1_000_000), 1_000_000_000_001_000);