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//! Contains types and helpers for dealing with `EXC_GUARD` exceptions.
//!
//! `EXC_GUARD` exceptions embed details about the guarded resource in the `code`
//! and `subcode` fields of the exception
//!
//! for the top level types that this module wraps.
use mach2::exception_types::EXC_GUARD;
/// The set of possible guard kinds
#[derive(Copy, Clone, Debug)]
#[repr(u8)]
pub enum GuardKind {
/// Null variant
None = 0,
/// A `mach_port_t`
MachPort = 1,
/// File descriptor
Fd = 2,
/// Userland assertion
User = 3,
/// Vnode
Vnode = 4,
/// Virtual memory operation
VirtualMemory = 5,
/// Rejected system call trap
RejectedSyscall = 6,
}
#[inline]
pub fn extract_guard_kind(code: u64) -> u8 {
((code >> 61) & 0x7) as u8
}
#[inline]
pub fn extract_guard_flavor(code: u64) -> u32 {
((code >> 32) & 0x1fffffff) as u32
}
#[inline]
pub fn extract_guard_target(code: u64) -> u32 {
code as u32
}
/// The extracted details of an `EXC_GUARD` exception
pub struct GuardException {
/// One of [`GuardKind`]
pub kind: u8,
/// The specific guard flavor that was violated, specific to each `kind`
pub flavor: u32,
/// The resource that was guarded
pub target: u32,
/// Target specific guard information
pub identifier: u64,
}
/// Extracts the guard details from an exceptions code and subcode
///
/// code:
/// +-------------------+----------------+--------------+
/// |[63:61] guard type | [60:32] flavor | [31:0] target|
/// +-------------------+----------------+--------------+
///
/// subcode:
/// +---------------------------------------------------+
/// |[63:0] guard identifier |
/// +---------------------------------------------------+
#[inline]
pub fn extract_guard_exception(code: u64, subcode: u64) -> GuardException {
GuardException {
kind: extract_guard_kind(code),
flavor: extract_guard_flavor(code),
target: extract_guard_target(code),
identifier: subcode,
}
}
impl super::ExceptionInfo {
/// If this is an `EXC_GUARD` exception, retrieves the exception metadata
/// from the code, otherwise returns `None`
pub fn guard_exception(&self) -> Option<GuardException> {
if self.kind != EXC_GUARD {
return None;
}
Some(extract_guard_exception(
self.code,
self.subcode.unwrap_or_default(),
))
}
}