95 lines
2.6 KiB
Rust
95 lines
2.6 KiB
Rust
use crate::error::ErrorStack;
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use foreign_types::{ForeignType, ForeignTypeRef};
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use libc::{c_char, c_int, c_void};
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use std::any::Any;
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use std::panic::{self, AssertUnwindSafe};
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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<dyn 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 "C" fn invoke_passwd_cb<F>(
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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
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F: FnOnce(&mut [u8]) -> Result<usize, ErrorStack>,
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{
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let callback = &mut *(cb_state as *mut CallbackState<F>);
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let result = panic::catch_unwind(AssertUnwindSafe(|| {
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let pass_slice = slice::from_raw_parts_mut(buf as *mut u8, size as usize);
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callback.cb.take().unwrap()(pass_slice)
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}));
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match result {
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Ok(Ok(len)) => len as c_int,
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Ok(Err(_)) => {
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// FIXME restore error stack
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0
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}
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Err(err) => {
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callback.panic = Some(err);
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0
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}
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}
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}
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#[allow(dead_code)]
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pub trait ForeignTypeExt: ForeignType {
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unsafe fn from_ptr_opt(ptr: *mut Self::CType) -> Option<Self> {
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if ptr.is_null() {
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None
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} else {
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Some(Self::from_ptr(ptr))
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}
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}
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}
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impl<FT: ForeignType> ForeignTypeExt for FT {}
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pub trait ForeignTypeRefExt: ForeignTypeRef {
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unsafe fn from_const_ptr<'a>(ptr: *const Self::CType) -> &'a Self {
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Self::from_ptr(ptr as *mut Self::CType)
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}
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unsafe fn from_const_ptr_opt<'a>(ptr: *const Self::CType) -> Option<&'a Self> {
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if ptr.is_null() {
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None
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} else {
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Some(Self::from_const_ptr(ptr as *mut Self::CType))
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}
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}
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}
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impl<FT: ForeignTypeRef> ForeignTypeRefExt for FT {}
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