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use libc::{c_int, c_char, c_void};
use std::any::Any;
use std::cell::UnsafeCell;
use std::panic::{self, AssertUnwindSafe};
use std::slice;
use error::ErrorStack;
/// 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<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);
}
}
}
pub unsafe extern fn invoke_passwd_cb_old<F>(buf: *mut c_char,
size: c_int,
_rwflag: c_int,
cb_state: *mut c_void)
-> c_int
where F: FnOnce(&mut [c_char]) -> usize
{
let callback = &mut *(cb_state as *mut CallbackState<F>);
let result = panic::catch_unwind(AssertUnwindSafe(|| {
let pass_slice = slice::from_raw_parts_mut(buf, size as usize);
callback.cb.take().unwrap()(pass_slice)
}));
match result {
Ok(len) => len as c_int,
Err(err) => {
callback.panic = Some(err);
0
}
}
}
/// Password callback function, passed to private key loading functions.
///
/// `cb_state` is expected to be a pointer to a `CallbackState`.
pub unsafe extern 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
}
}
}
/// This is intended to be used as the inner type for `FooRef` types converted from raw C pointers.
/// It has an `UnsafeCell` internally to inform the compiler about aliasability and doesn't
/// implement `Copy`, so it can't be dereferenced.
pub struct Opaque(UnsafeCell<()>);
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