openssl/
util.rs

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1use crate::error::ErrorStack;
2use crate::util;
3use foreign_types::{ForeignType, ForeignTypeRef};
4use libc::{c_char, c_int, c_void};
5use std::any::Any;
6use std::panic::{self, AssertUnwindSafe};
7use std::slice;
8
9/// Wraps a user-supplied callback and a slot for panics thrown inside the callback (while FFI
10/// frames are on the stack).
11///
12/// When dropped, checks if the callback has panicked, and resumes unwinding if so.
13pub struct CallbackState<F> {
14    /// The user callback. Taken out of the `Option` when called.
15    cb: Option<F>,
16    /// If the callback panics, we place the panic object here, to be re-thrown once OpenSSL
17    /// returns.
18    panic: Option<Box<dyn Any + Send + 'static>>,
19}
20
21impl<F> CallbackState<F> {
22    pub fn new(callback: F) -> Self {
23        CallbackState {
24            cb: Some(callback),
25            panic: None,
26        }
27    }
28}
29
30impl<F> Drop for CallbackState<F> {
31    fn drop(&mut self) {
32        if let Some(panic) = self.panic.take() {
33            panic::resume_unwind(panic);
34        }
35    }
36}
37
38/// Password callback function, passed to private key loading functions.
39///
40/// `cb_state` is expected to be a pointer to a `CallbackState`.
41pub unsafe extern "C" fn invoke_passwd_cb<F>(
42    buf: *mut c_char,
43    size: c_int,
44    _rwflag: c_int,
45    cb_state: *mut c_void,
46) -> c_int
47where
48    F: FnOnce(&mut [u8]) -> Result<usize, ErrorStack>,
49{
50    let callback = &mut *(cb_state as *mut CallbackState<F>);
51
52    let result = panic::catch_unwind(AssertUnwindSafe(|| {
53        let pass_slice = util::from_raw_parts_mut(buf as *mut u8, size as usize);
54        callback.cb.take().unwrap()(pass_slice)
55    }));
56
57    match result {
58        Ok(Ok(len)) => len as c_int,
59        Ok(Err(_)) => {
60            // FIXME restore error stack
61            0
62        }
63        Err(err) => {
64            callback.panic = Some(err);
65            0
66        }
67    }
68}
69
70pub trait ForeignTypeExt: ForeignType {
71    unsafe fn from_ptr_opt(ptr: *mut Self::CType) -> Option<Self> {
72        if ptr.is_null() {
73            None
74        } else {
75            Some(Self::from_ptr(ptr))
76        }
77    }
78}
79impl<FT: ForeignType> ForeignTypeExt for FT {}
80
81pub trait ForeignTypeRefExt: ForeignTypeRef {
82    unsafe fn from_const_ptr<'a>(ptr: *const Self::CType) -> &'a Self {
83        Self::from_ptr(ptr as *mut Self::CType)
84    }
85
86    unsafe fn from_const_ptr_opt<'a>(ptr: *const Self::CType) -> Option<&'a Self> {
87        if ptr.is_null() {
88            None
89        } else {
90            Some(Self::from_const_ptr(ptr as *mut Self::CType))
91        }
92    }
93}
94impl<FT: ForeignTypeRef> ForeignTypeRefExt for FT {}
95
96/// The same as `slice::from_raw_parts`, except that `data` may be `NULL` if
97/// `len` is 0.
98pub unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T] {
99    if len == 0 {
100        &[]
101    } else {
102        // Using this to implement the preferred API
103        #[allow(clippy::disallowed_methods)]
104        slice::from_raw_parts(data, len)
105    }
106}
107
108/// The same as `slice::from_raw_parts_mut`, except that `data` may be `NULL`
109/// if `len` is 0.
110pub unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a mut [T] {
111    if len == 0 {
112        &mut []
113    } else {
114        // Using this to implement the preferred API
115        #[allow(clippy::disallowed_methods)]
116        slice::from_raw_parts_mut(data, len)
117    }
118}
openssl/util.rs

openssl/
util.rs
