--- a/libpam-sys/src/structs.rs	Mon Jun 30 04:54:38 2025 -0400
+++ b/libpam-sys/src/structs.rs	Mon Jun 30 17:47:32 2025 -0400
@@ -1,11 +1,17 @@
+//! Structs and wrappers that PAM is made of.
+#![allow(non_camel_case_types)]
+
 use std::ffi::{c_int, c_void};
 use std::fmt;
 use std::marker::{PhantomData, PhantomPinned};
 
 /// A marker struct to make whatever it's in `!Sync`, `!Send`, and `!Unpin`.
 #[derive(Default, PartialOrd, PartialEq, Ord, Eq)]
-#[repr(transparent)]
-struct ExtremelyUnsafe(PhantomData<(PhantomPinned, *mut c_void)>);
+#[repr(C)]
+struct ExtremelyUnsafe {
+    _value: (),
+    _marker: PhantomData<(PhantomPinned, *mut c_void)>,
+}
 
 impl fmt::Debug for ExtremelyUnsafe {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -17,20 +23,17 @@
 ///
 /// This is only ever returned in pointer form and cannot be constructed.
 #[repr(C)]
-pub struct PamHandle {
-    _marker: ExtremelyUnsafe,
-}
+pub struct pam_handle_t(ExtremelyUnsafe);
 
-impl fmt::Debug for PamHandle {
+impl fmt::Debug for pam_handle_t {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "PamHandle({self:p}")
     }
 }
 
 /// An opaque structure that is passed through PAM in a conversation.
-pub struct AppData {
-    _marker: ExtremelyUnsafe,
-}
+#[repr(C)]
+pub struct AppData(ExtremelyUnsafe);
 
 impl fmt::Debug for AppData {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -47,30 +50,38 @@
     // This is a *const *const because accessing memory from a reference
     // outside its bounds is undefined behavior, and *messages is an array
     // in X/SSO PAM impls.
-    messages: *const *const Message,
-    // This is a &mut *mut because the caller sets the pointer in `responses`
+    msg: *const *const pam_message,
+    // This is a &mut *mut because the caller sets the pointer in `resp`
     // but does not mess around outside its memory space.
-    responses: &mut *mut Response,
+    resp: &mut *mut pam_response,
     appdata: *const AppData,
 ) -> c_int;
 
+/// Called to clean up data set using [`pam_set_data`](crate::pam_set_data).
+pub type CleanupCallback = unsafe extern "C" fn(
+    pamh: *mut pam_handle_t,
+    data: *mut c_void,
+    pam_end_status: c_int,
+) -> c_int;
+
 /// Used by PAM to communicate between the module and the application.
 #[repr(C)]
-pub struct Conversation {
-    pub callback: ConversationCallback,
-    pub appdata: *const AppData,
+pub struct pam_conv {
+    pub conv: ConversationCallback,
+    pub appdata_ptr: *const AppData,
 }
 
 /// A message sent into a PAM conversation.
 #[repr(C)]
-pub struct Message {
-    pub style: c_int,
-    pub data: *const c_void,
+pub struct pam_message {
+    pub msg_style: c_int,
+    pub msg: *const c_void,
 }
 
 /// A response returned from a PAM conversation.
 #[repr(C)]
-pub struct Response {
-    pub data: *mut c_void,
-    pub _unused: c_int,
+pub struct pam_response {
+    pub resp: *mut c_void,
+    /// Completely unused.
+    pub resp_retcode: c_int,
 }