src/libstd/sys_common/mod.rs

   1 //! Platform-independent platform abstraction
   2 //!
   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.
   6 //!
   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.
  14
  15 #![allow(missing_docs)]
  16 #![allow(missing_debug_implementations)]
  17
  18 use crate::sync::Once;
  19 use crate::sys;
  20
  21 macro_rules! rtabort {
  22     ($($t:tt)*) => (crate::sys_common::util::abort(format_args!($($t)*)))
  23 }
  24
  25 macro_rules! rtassert {
  26     ($e:expr) => (if !$e {
  27         rtabort!(concat!("assertion failed: ", stringify!($e)));
  28     })
  29 }
  30
  31 #[allow(unused_macros)] // not used on all platforms
  32 macro_rules! rtunwrap {
  33     ($ok:ident, $e:expr) => (match $e {
  34         $ok(v) => v,
  35         ref err => {
  36             let err = err.as_ref().map(|_|()); // map Ok/Some which might not be Debug
  37             rtabort!(concat!("unwrap failed: ", stringify!($e), " = {:?}"), err)
  38         },
  39     })
  40 }
  41
  42 pub mod alloc;
  43 pub mod at_exit_imp;
  44 pub mod backtrace;
  45 pub mod condvar;
  46 pub mod io;
  47 pub mod mutex;
  48 #[cfg(any(doc, // see `mod os`, docs are generated for multiple platforms
  49           unix,
  50           target_os = "redox",
  51           target_os = "cloudabi",
  52           target_os = "hermit",
  53           target_arch = "wasm32",
  54           all(target_vendor = "fortanix", target_env = "sgx")))]
  55 pub mod os_str_bytes;
  56 pub mod poison;
  57 pub mod remutex;
  58 pub mod rwlock;
  59 pub mod thread;
  60 pub mod thread_info;
  61 pub mod thread_local;
  62 pub mod util;
  63 pub mod wtf8;
  64 pub mod bytestring;
  65 pub mod process;
  66 pub mod fs;
  67
  68 cfg_if::cfg_if! {
  69     if #[cfg(any(target_os = "cloudabi",
  70                  target_os = "l4re",
  71                  target_os = "hermit",
  72                  all(target_arch = "wasm32", not(target_os = "emscripten")),
  73                  all(target_vendor = "fortanix", target_env = "sgx")))] {
  74         pub use crate::sys::net;
  75     } else {
  76         pub mod net;
  77     }
  78 }
  79
  80 // common error constructors
  81
  82 /// A trait for viewing representations from std types
  83 #[doc(hidden)]
  84 pub trait AsInner<Inner: ?Sized> {
  85     fn as_inner(&self) -> &Inner;
  86 }
  87
  88 /// A trait for viewing representations from std types
  89 #[doc(hidden)]
  90 pub trait AsInnerMut<Inner: ?Sized> {
  91     fn as_inner_mut(&mut self) -> &mut Inner;
  92 }
  93
  94 /// A trait for extracting representations from std types
  95 #[doc(hidden)]
  96 pub trait IntoInner<Inner> {
  97     fn into_inner(self) -> Inner;
  98 }
  99
 100 /// A trait for creating std types from internal representations
 101 #[doc(hidden)]
 102 pub trait FromInner<Inner> {
 103     fn from_inner(inner: Inner) -> Self;
 104 }
 105
 106 /// Enqueues a procedure to run when the main thread exits.
 107 ///
 108 /// Currently these closures are only run once the main *Rust* thread exits.
 109 /// Once the `at_exit` handlers begin running, more may be enqueued, but not
 110 /// infinitely so. Eventually a handler registration will be forced to fail.
 111 ///
 112 /// Returns `Ok` if the handler was successfully registered, meaning that the
 113 /// closure will be run once the main thread exits. Returns `Err` to indicate
 114 /// that the closure could not be registered, meaning that it is not scheduled
 115 /// to be run.
 116 pub fn at_exit<F: FnOnce() + Send + 'static>(f: F) -> Result<(), ()> {
 117     if at_exit_imp::push(Box::new(f)) {Ok(())} else {Err(())}
 118 }
 119
 120 /// One-time runtime cleanup.
 121 pub fn cleanup() {
 122     static CLEANUP: Once = Once::new();
 123     CLEANUP.call_once(|| unsafe {
 124         sys::args::cleanup();
 125         sys::stack_overflow::cleanup();
 126         at_exit_imp::cleanup();
 127     });
 128 }
 129
 130 // Computes (value*numer)/denom without overflow, as long as both
 131 // (numer*denom) and the overall result fit into i64 (which is the case
 132 // for our time conversions).
 133 #[allow(dead_code)] // not used on all platforms
 134 pub fn mul_div_u64(value: u64, numer: u64, denom: u64) -> u64 {
 135     let q = value / denom;
 136     let r = value % denom;
 137     // Decompose value as (value/denom*denom + value%denom),
 138     // substitute into (value*numer)/denom and simplify.
 139     // r < denom, so (denom*numer) is the upper bound of (r*numer)
 140     q * numer + r * numer / denom
 141 }
 142
 143 #[test]
 144 fn test_muldiv() {
 145     assert_eq!(mul_div_u64( 1_000_000_000_001, 1_000_000_000, 1_000_000),
 146                1_000_000_000_001_000);
 147 }