crash_handler/linux/
jmp.rs

1//! FFI bindings for non-local goto
2//!
3//! ```
4//! use crash_handler::jmp;
5//!
6//! unsafe {
7//!     let mut jmp_buf = std::mem::MaybeUninit::uninit();
8//!
9//!     let val = jmp::sigsetjmp(jmp_buf.as_mut_ptr(), 1);
10//!
11//!     if val == 0 {
12//!         jmp::siglongjmp(jmp_buf.as_mut_ptr(), 22);
13//!     } else {
14//!         assert_eq!(val, 22);
15//!     }
16//! }
17//! ```
18
19cfg_if::cfg_if! {
20    if #[cfg(target_arch = "x86_64")] {
21        #[repr(C)]
22        #[doc(hidden)]
23        #[allow(non_camel_case_types)]
24        pub struct __jmp_buf([u64; 8]);
25    } else if #[cfg(target_arch = "x86")] {
26        #[repr(C)]
27        #[doc(hidden)]
28        #[allow(non_camel_case_types)]
29        pub struct __jmp_buf([u32; 6]);
30    } else if #[cfg(target_arch = "arm")] {
31        #[repr(C)]
32        #[doc(hidden)]
33        #[allow(non_camel_case_types)]
34        pub struct __jmp_buf([u64; 32]);
35    } else if #[cfg(target_arch = "aarch64")] {
36        #[repr(C)]
37        #[doc(hidden)]
38        #[allow(non_camel_case_types)]
39        pub struct __jmp_buf([u64; 22]);
40    }
41}
42
43/// A jump buffer.
44///
45/// This is essentially the register state of a point in execution at the time
46/// of a [`sigsetjmp`] call that can be returned to by passing this buffer to
47/// [`siglongjmp`].
48#[repr(C)]
49pub struct JmpBuf {
50    /// CPU context
51    __jmp_buf: __jmp_buf,
52    /// Whether the signal mask was saved
53    __fl: u32,
54    /// Saved signal mask
55    __ss: [u32; 32],
56}
57
58unsafe extern "C" {
59    /// Set jump point for a non-local goto.
60    ///
61    /// The return value will be 0 if this is a direct invocation (ie the "first
62    /// time" `sigsetjmp` is executed), and will be the value passed to `siglongjmp`
63    /// otherwise.
64    ///
65    /// See [sigsetjmp](https://man7.org/linux/man-pages/man3/sigsetjmp.3p.html)
66    /// for more information.
67    #[cfg_attr(target_env = "gnu", link_name = "__sigsetjmp")]
68    pub fn sigsetjmp(jb: *mut JmpBuf, save_mask: i32) -> i32;
69    /// Non-local goto with signal handling
70    ///
71    /// The value passed here will be returned by `sigsetjmp` when returning
72    /// to that callsite. Note that passing a value of 0 here will be changed
73    /// to a 1.
74    ///
75    /// See [siglongjmp](https://man7.org/linux/man-pages/man3/siglongjmp.3p.html)
76    /// for more information.
77    pub fn siglongjmp(jb: *mut JmpBuf, val: i32) -> !;
78}
crash_handler/linux/jmp.rs

crash_handler/linux/
jmp.rs
