library/std/src/rt.rs

   1 //! Runtime services
   2 //!
   3 //! The `rt` module provides a narrow set of runtime services,
   4 //! including the global heap (exported in `heap`) and unwinding and
   5 //! backtrace support. The APIs in this module are highly unstable,
   6 //! and should be considered as private implementation details for the
   7 //! time being.
   8
   9 #![unstable(
  10     feature = "rt",
  11     reason = "this public module should not exist and is highly likely \
  12               to disappear",
  13     issue = "none"
  14 )]
  15 #![doc(hidden)]
  16
  17 // Re-export some of our utilities which are expected by other crates.
  18 pub use crate::panicking::{begin_panic, begin_panic_fmt, panic_count};
  19
  20 // To reduce the generated code of the new `lang_start`, this function is doing
  21 // the real work.
  22 #[cfg(not(test))]
  23 fn lang_start_internal(
  24     main: &(dyn Fn() -> i32 + Sync + crate::panic::RefUnwindSafe),
  25     argc: isize,
  26     argv: *const *const u8,
  27 ) -> isize {
  28     use crate::panic;
  29     use crate::sys;
  30     use crate::sys_common;
  31     use crate::sys_common::thread_info;
  32     use crate::thread::Thread;
  33
  34     sys::init();
  35
  36     unsafe {
  37         let main_guard = sys::thread::guard::init();
  38         sys::stack_overflow::init();
  39
  40         // Next, set up the current Thread with the guard information we just
  41         // created. Note that this isn't necessary in general for new threads,
  42         // but we just do this to name the main thread and to give it correct
  43         // info about the stack bounds.
  44         let thread = Thread::new(Some("main".to_owned()));
  45         thread_info::set(main_guard, thread);
  46
  47         // Store our args if necessary in a squirreled away location
  48         sys::args::init(argc, argv);
  49
  50         // Let's run some code!
  51         let exit_code = panic::catch_unwind(main);
  52
  53         sys_common::cleanup();
  54         exit_code.unwrap_or(101) as isize
  55     }
  56 }
  57
  58 #[cfg(not(test))]
  59 #[lang = "start"]
  60 fn lang_start<T: crate::process::Termination + 'static>(
  61     main: fn() -> T,
  62     argc: isize,
  63     argv: *const *const u8,
  64 ) -> isize {
  65     lang_start_internal(
  66         &move || crate::sys_common::backtrace::__rust_begin_short_backtrace(main).report(),
  67         argc,
  68         argv,
  69     )
  70 }