59 lines
1.8 KiB
Rust
59 lines
1.8 KiB
Rust
use libc::{c_int, c_char, c_void};
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use std::any::Any;
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use std::panic;
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use std::slice;
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/// Wraps a user-supplied callback and a slot for panics thrown inside the callback (while FFI
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/// frames are on the stack).
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///
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/// When dropped, checks if the callback has panicked, and resumes unwinding if so.
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pub struct CallbackState<F> {
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/// The user callback. Taken out of the `Option` when called.
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cb: Option<F>,
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/// If the callback panics, we place the panic object here, to be re-thrown once OpenSSL
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/// returns.
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panic: Option<Box<Any + Send + 'static>>,
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}
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impl<F> CallbackState<F> {
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pub fn new(callback: F) -> Self {
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CallbackState {
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cb: Some(callback),
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panic: None,
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}
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}
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}
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impl<F> Drop for CallbackState<F> {
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fn drop(&mut self) {
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if let Some(panic) = self.panic.take() {
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panic::resume_unwind(panic);
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}
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}
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}
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/// Password callback function, passed to private key loading functions.
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///
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/// `cb_state` is expected to be a pointer to a `CallbackState`.
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pub unsafe extern fn invoke_passwd_cb<F>(buf: *mut c_char,
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size: c_int,
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_rwflag: c_int,
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cb_state: *mut c_void)
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-> c_int
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where F: FnOnce(&mut [c_char]) -> usize {
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let result = panic::catch_unwind(|| {
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// build a `i8` slice to pass to the user callback
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let pass_slice = slice::from_raw_parts_mut(buf, size as usize);
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let callback = &mut *(cb_state as *mut CallbackState<F>);
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callback.cb.take().unwrap()(pass_slice)
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});
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if let Ok(len) = result {
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return len as c_int;
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} else {
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return 0;
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}
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}
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