1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
|
//! Runtime services
//!
//! The `rt` module provides a narrow set of runtime services,
//! including the global heap (exported in `heap`) and unwinding and
//! backtrace support. The APIs in this module are highly unstable,
//! and should be considered as private implementation details for the
//! time being.
#![unstable(
feature = "rt",
reason = "this public module should not exist and is highly likely \
to disappear",
issue = "none"
)]
#![doc(hidden)]
#![deny(unsafe_op_in_unsafe_fn)]
#![allow(unused_macros)]
use crate::ffi::CString;
// Re-export some of our utilities which are expected by other crates.
pub use crate::panicking::{begin_panic, panic_count};
pub use core::panicking::{panic_display, panic_fmt};
use crate::sync::Once;
use crate::sys;
use crate::sys_common::thread_info;
use crate::thread::Thread;
// Prints to the "panic output", depending on the platform this may be:
// - the standard error output
// - some dedicated platform specific output
// - nothing (so this macro is a no-op)
macro_rules! rtprintpanic {
($($t:tt)*) => {
if let Some(mut out) = crate::sys::stdio::panic_output() {
let _ = crate::io::Write::write_fmt(&mut out, format_args!($($t)*));
}
}
}
macro_rules! rtabort {
($($t:tt)*) => {
{
rtprintpanic!("fatal runtime error: {}\n", format_args!($($t)*));
crate::sys::abort_internal();
}
}
}
macro_rules! rtassert {
($e:expr) => {
if !$e {
rtabort!(concat!("assertion failed: ", stringify!($e)));
}
};
}
macro_rules! rtunwrap {
($ok:ident, $e:expr) => {
match $e {
$ok(v) => v,
ref err => {
let err = err.as_ref().map(drop); // map Ok/Some which might not be Debug
rtabort!(concat!("unwrap failed: ", stringify!($e), " = {:?}"), err)
}
}
};
}
// One-time runtime initialization.
// Runs before `main`.
// SAFETY: must be called only once during runtime initialization.
// NOTE: this is not guaranteed to run, for example when Rust code is called externally.
//
// # The `sigpipe` parameter
//
// Since 2014, the Rust runtime on Unix has set the `SIGPIPE` handler to
// `SIG_IGN`. Applications have good reasons to want a different behavior
// though, so there is a `#[unix_sigpipe = "..."]` attribute on `fn main()` that
// can be used to select how `SIGPIPE` shall be setup (if changed at all) before
// `fn main()` is called. See <https://github.com/rust-lang/rust/issues/97889>
// for more info.
//
// The `sigpipe` parameter to this function gets its value via the code that
// rustc generates to invoke `fn lang_start()`. The reason we have `sigpipe` for
// all platforms and not only Unix, is because std is not allowed to have `cfg`
// directives as this high level. See the module docs in
// `src/tools/tidy/src/pal.rs` for more info. On all other platforms, `sigpipe`
// has a value, but its value is ignored.
//
// Even though it is an `u8`, it only ever has 4 values. These are documented in
// `compiler/rustc_session/src/config/sigpipe.rs`.
#[cfg_attr(test, allow(dead_code))]
unsafe fn init(argc: isize, argv: *const *const u8, sigpipe: u8) {
unsafe {
sys::init(argc, argv, sigpipe);
let main_guard = sys::thread::guard::init();
// Next, set up the current Thread with the guard information we just
// created. Note that this isn't necessary in general for new threads,
// but we just do this to name the main thread and to give it correct
// info about the stack bounds.
let thread = Thread::new(Some(rtunwrap!(Ok, CString::new("main"))));
thread_info::set(main_guard, thread);
}
}
// One-time runtime cleanup.
// Runs after `main` or at program exit.
// NOTE: this is not guaranteed to run, for example when the program aborts.
pub(crate) fn cleanup() {
static CLEANUP: Once = Once::new();
CLEANUP.call_once(|| unsafe {
// Flush stdout and disable buffering.
crate::io::cleanup();
// SAFETY: Only called once during runtime cleanup.
sys::cleanup();
});
}
// To reduce the generated code of the new `lang_start`, this function is doing
// the real work.
#[cfg(not(test))]
fn lang_start_internal(
main: &(dyn Fn() -> i32 + Sync + crate::panic::RefUnwindSafe),
argc: isize,
argv: *const *const u8,
sigpipe: u8,
) -> Result<isize, !> {
use crate::{mem, panic};
let rt_abort = move |e| {
mem::forget(e);
rtabort!("initialization or cleanup bug");
};
// Guard against the code called by this function from unwinding outside of the Rust-controlled
// code, which is UB. This is a requirement imposed by a combination of how the
// `#[lang="start"]` attribute is implemented as well as by the implementation of the panicking
// mechanism itself.
//
// There are a couple of instances where unwinding can begin. First is inside of the
// `rt::init`, `rt::cleanup` and similar functions controlled by bstd. In those instances a
// panic is a std implementation bug. A quite likely one too, as there isn't any way to
// prevent std from accidentally introducing a panic to these functions. Another is from
// user code from `main` or, more nefariously, as described in e.g. issue #86030.
// SAFETY: Only called once during runtime initialization.
panic::catch_unwind(move || unsafe { init(argc, argv, sigpipe) }).map_err(rt_abort)?;
let ret_code = panic::catch_unwind(move || panic::catch_unwind(main).unwrap_or(101) as isize)
.map_err(move |e| {
mem::forget(e);
rtabort!("drop of the panic payload panicked");
});
panic::catch_unwind(cleanup).map_err(rt_abort)?;
ret_code
}
#[cfg(not(test))]
#[inline(never)]
#[lang = "start"]
fn lang_start<T: crate::process::Termination + 'static>(
main: fn() -> T,
argc: isize,
argv: *const *const u8,
sigpipe: u8,
) -> isize {
let Ok(v) = lang_start_internal(
&move || crate::sys_common::backtrace::__rust_begin_short_backtrace(main).report().to_i32(),
argc,
argv,
sigpipe,
);
v
}
|
