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use crate::error::ErrorStack;
use foreign_types::{ForeignType, ForeignTypeRef};
use libc::{c_char, c_int, c_void};
use std::any::Any;
use std::panic::{self, AssertUnwindSafe};
use std::slice;
/// Wraps a user-supplied callback and a slot for panics thrown inside the callback (while FFI
/// frames are on the stack).
///
/// When dropped, checks if the callback has panicked, and resumes unwinding if so.
pub struct CallbackState<F> {
/// The user callback. Taken out of the `Option` when called.
cb: Option<F>,
/// If the callback panics, we place the panic object here, to be re-thrown once OpenSSL
/// returns.
panic: Option<Box<dyn Any + Send + 'static>>,
}
impl<F> CallbackState<F> {
pub fn new(callback: F) -> Self {
CallbackState {
cb: Some(callback),
panic: None,
}
}
}
impl<F> Drop for CallbackState<F> {
fn drop(&mut self) {
if let Some(panic) = self.panic.take() {
panic::resume_unwind(panic);
}
}
}
/// Password callback function, passed to private key loading functions.
///
/// `cb_state` is expected to be a pointer to a `CallbackState`.
pub unsafe extern "C" fn invoke_passwd_cb<F>(
buf: *mut c_char,
size: c_int,
_rwflag: c_int,
cb_state: *mut c_void,
) -> c_int
where
F: FnOnce(&mut [u8]) -> Result<usize, ErrorStack>,
{
let callback = &mut *(cb_state as *mut CallbackState<F>);
let result = panic::catch_unwind(AssertUnwindSafe(|| {
let pass_slice = slice::from_raw_parts_mut(buf as *mut u8, size as usize);
callback.cb.take().unwrap()(pass_slice)
}));
match result {
Ok(Ok(len)) => len as c_int,
Ok(Err(_)) => {
// FIXME restore error stack
0
}
Err(err) => {
callback.panic = Some(err);
0
}
}
}
pub trait ForeignTypeExt: ForeignType {
unsafe fn from_ptr_opt(ptr: *mut Self::CType) -> Option<Self> {
if ptr.is_null() {
None
} else {
Some(Self::from_ptr(ptr))
}
}
}
impl<FT: ForeignType> ForeignTypeExt for FT {}
pub trait ForeignTypeRefExt: ForeignTypeRef {
unsafe fn from_const_ptr<'a>(ptr: *const Self::CType) -> &'a Self {
Self::from_ptr(ptr as *mut Self::CType)
}
unsafe fn from_const_ptr_opt<'a>(ptr: *const Self::CType) -> Option<&'a Self> {
if ptr.is_null() {
None
} else {
Some(Self::from_const_ptr(ptr as *mut Self::CType))
}
}
}
impl<FT: ForeignTypeRef> ForeignTypeRefExt for FT {}
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