Flatten crypto module

1 files changed, 61 insertions, 0 deletions

diff --git a/openssl/src/util.rs b/openssl/src/util.rs
new file mode 100644
index 00000000..68d9b32a
--- /dev/null
+++ b/openssl/src/util.rs
@@ -0,0 +1,61 @@
+use libc::{c_int, c_char, 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<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 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 [c_char]) -> usize {
+    let callback = &mut *(cb_state as *mut CallbackState<F>);
+
+    let result = panic::catch_unwind(AssertUnwindSafe(|| {
+        // build a `i8` slice to pass to the user callback
+        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
+        }
+    }
+}