ffi: Use *const T for non-optional arguments.

  - Previously, Option<&T> was used, primarily because it was more
    ergonomic in Rust.  However, this gave the impression that the
    argument was optional.

  - Likewise for mutable references.

  - This patch addresses all pointers to Rust values.

  - See #149.

11 files changed, 263 insertions, 256 deletions

diff --git a/ffi/src/core.rs b/ffi/src/core.rs
index 53bf5217..bb65d09c 100644
--- a/ffi/src/core.rs
+++ b/ffi/src/core.rs
@@ -62,7 +62,7 @@ impl Context {
 ///
 /// Returns and removes the last error from the context.
 #[no_mangle]
-pub extern "system" fn sq_context_last_error(ctx: Option<&mut Context>)
+pub extern "system" fn sq_context_last_error(ctx: *mut Context)
                                              -> *mut failure::Error {
     let ctx = ffi_param_ref_mut!(ctx);
     maybe_box_raw!(ctx.e.take())
@@ -133,42 +133,42 @@ pub extern "system" fn sq_context_configure(domain: *const c_char)
 
 /// Returns the domain of the context.
 #[no_mangle]
-pub extern "system" fn sq_context_domain(ctx: Option<&Context>) -> *const c_char {
+pub extern "system" fn sq_context_domain(ctx: *const Context) -> *const c_char {
     let ctx = ffi_param_ref!(ctx);
     ctx.c.domain().as_bytes().as_ptr() as *const c_char
 }
 
 /// Returns the directory containing shared state.
 #[no_mangle]
-pub extern "system" fn sq_context_home(ctx: Option<&Context>) -> *const c_char {
+pub extern "system" fn sq_context_home(ctx: *const Context) -> *const c_char {
     let ctx = ffi_param_ref!(ctx);
     ctx.c.home().to_string_lossy().as_ptr() as *const c_char
 }
 
 /// Returns the directory containing backend servers.
 #[no_mangle]
-pub extern "system" fn sq_context_lib(ctx: Option<&Context>) -> *const c_char {
+pub extern "system" fn sq_context_lib(ctx: *const Context) -> *const c_char {
     let ctx = ffi_param_ref!(ctx);
     ctx.c.lib().to_string_lossy().as_bytes().as_ptr() as *const c_char
 }
 
 /// Returns the network policy.
 #[no_mangle]
-pub extern "system" fn sq_context_network_policy(ctx: Option<&Context>) -> c_int {
+pub extern "system" fn sq_context_network_policy(ctx: *const Context) -> c_int {
     let ctx = ffi_param_ref!(ctx);
     u8::from(ctx.c.network_policy()) as c_int
 }
 
 /// Returns the IPC policy.
 #[no_mangle]
-pub extern "system" fn sq_context_ipc_policy(ctx: Option<&Context>) -> c_int {
+pub extern "system" fn sq_context_ipc_policy(ctx: *const Context) -> c_int {
     let ctx = ffi_param_ref!(ctx);
     u8::from(ctx.c.ipc_policy()) as c_int
 }
 
 /// Returns whether or not this is an ephemeral context.
 #[no_mangle]
-pub extern "system" fn sq_context_ephemeral(ctx: Option<&Context>) -> uint8_t {
+pub extern "system" fn sq_context_ephemeral(ctx: *const Context) -> uint8_t {
     let ctx = ffi_param_ref!(ctx);
     if ctx.c.ephemeral() { 1 } else { 0 }
 }
@@ -200,7 +200,7 @@ pub extern "system" fn sq_config_build(cfg: *mut Config,
 
 /// Sets the directory containing shared state.
 #[no_mangle]
-pub extern "system" fn sq_config_home(cfg: Option<&mut Config>,
+pub extern "system" fn sq_config_home(cfg: *mut Config,
                                       home: *const c_char) {
     let cfg = ffi_param_ref_mut!(cfg);
     assert!(! home.is_null());
@@ -212,7 +212,7 @@ pub extern "system" fn sq_config_home(cfg: Option<&mut Config>,
 
 /// Set the directory containing backend servers.
 #[no_mangle]
-pub extern "system" fn sq_config_lib(cfg: Option<&mut Config>,
+pub extern "system" fn sq_config_lib(cfg: *mut Config,
                                      lib: *const c_char) {
     let cfg = ffi_param_ref_mut!(cfg);
     assert!(! lib.is_null());
@@ -224,7 +224,7 @@ pub extern "system" fn sq_config_lib(cfg: Option<&mut Config>,
 
 /// Sets the network policy.
 #[no_mangle]
-pub extern "system" fn sq_config_network_policy(cfg: Option<&mut Config>,
+pub extern "system" fn sq_config_network_policy(cfg: *mut Config,
                                                 policy: c_int) {
     let cfg = ffi_param_ref_mut!(cfg);
     if policy < 0 || policy > 3 {
@@ -235,7 +235,7 @@ pub extern "system" fn sq_config_network_policy(cfg: Option<&mut Config>,
 
 /// Sets the IPC policy.
 #[no_mangle]
-pub extern "system" fn sq_config_ipc_policy(cfg: Option<&mut Config>,
+pub extern "system" fn sq_config_ipc_policy(cfg: *mut Config,
                                             policy: c_int) {
     let cfg = ffi_param_ref_mut!(cfg);
     if policy < 0 || policy > 2 {
@@ -246,7 +246,7 @@ pub extern "system" fn sq_config_ipc_policy(cfg: Option<&mut Config>,
 
 /// Makes this context ephemeral.
 #[no_mangle]
-pub extern "system" fn sq_config_ephemeral(cfg: Option<&mut Config>) {
+pub extern "system" fn sq_config_ephemeral(cfg: *mut Config) {
     let cfg = ffi_param_ref_mut!(cfg);
     cfg.set_ephemeral();
 }
@@ -255,7 +255,7 @@ pub extern "system" fn sq_config_ephemeral(cfg: Option<&mut Config>) {
 
 /// Opens a file returning a reader.
 #[no_mangle]
-pub extern "system" fn sq_reader_from_file(ctx: Option<&mut Context>,
+pub extern "system" fn sq_reader_from_file(ctx: *mut Context,
                                            filename: *const c_char)
                                            -> *mut Box<Read> {
     let ctx = ffi_param_ref_mut!(ctx);
@@ -296,8 +296,8 @@ pub extern "system" fn sq_reader_free(reader: *mut Box<Read>) {
 
 /// Reads up to `len` bytes into `buf`.
 #[no_mangle]
-pub extern "system" fn sq_reader_read(ctx: Option<&mut Context>,
-                                      reader: Option<&mut Box<Read>>,
+pub extern "system" fn sq_reader_read(ctx: *mut Context,
+                                      reader: *mut Box<Read>,
                                       buf: *mut uint8_t, len: size_t)
                                       -> ssize_t {
     let ctx = ffi_param_ref_mut!(ctx);
@@ -315,7 +315,7 @@ pub extern "system" fn sq_reader_read(ctx: Option<&mut Context>,
 /// The file will be created if it does not exist, or be truncated
 /// otherwise.  If you need more control, use `sq_writer_from_fd`.
 #[no_mangle]
-pub extern "system" fn sq_writer_from_file(ctx: Option<&mut Context>,
+pub extern "system" fn sq_writer_from_file(ctx: *mut Context,
                                            filename: *const c_char)
                                            -> *mut Box<Write> {
     let ctx = ffi_param_ref_mut!(ctx);
@@ -357,8 +357,8 @@ pub extern "system" fn sq_writer_from_bytes(buf: *mut uint8_t,
 /// The caller is responsible to `free` it once the writer has been
 /// destroyed.
 #[no_mangle]
-pub extern "system" fn sq_writer_alloc(buf: Option<&'static mut *mut c_void>,
-                                       len: Option<&'static mut size_t>)
+pub extern "system" fn sq_writer_alloc(buf: *mut *mut c_void,
+                                       len: *mut size_t)
                                        -> *mut Box<Write> {
     let buf = ffi_param_ref_mut!(buf);
     let len = ffi_param_ref_mut!(len);
@@ -410,8 +410,8 @@ pub extern "system" fn sq_writer_free(writer: *mut Box<Write>) {
 
 /// Writes up to `len` bytes of `buf` into `writer`.
 #[no_mangle]
-pub extern "system" fn sq_writer_write(ctx: Option<&mut Context>,
-                                       writer: Option<&mut Box<Write>>,
+pub extern "system" fn sq_writer_write(ctx: *mut Context,
+                                       writer: *mut Box<Write>,
                                        buf: *const uint8_t, len: size_t)
                                        -> ssize_t {
     let ctx = ffi_param_ref_mut!(ctx);
diff --git a/ffi/src/error.rs b/ffi/src/error.rs
index e54139d1..25640556 100644
--- a/ffi/src/error.rs
+++ b/ffi/src/error.rs
@@ -18,7 +18,7 @@ pub extern "system" fn sq_error_free(error: *mut failure::Error) {
 ///
 /// The returned value must be freed with `sq_string_free`.
 #[no_mangle]
-pub extern "system" fn sq_error_string(error: Option<&failure::Error>)
+pub extern "system" fn sq_error_string(error: *const failure::Error)
                                        -> *mut c_char {
     let error = ffi_param_ref!(error);
     CString::new(format!("{}", error))
@@ -29,7 +29,7 @@ pub extern "system" fn sq_error_string(error: Option<&failure::Error>)
 
 /// Returns the error status code.
 #[no_mangle]
-pub extern "system" fn sq_error_status(error: Option<&failure::Error>)
+pub extern "system" fn sq_error_status(error: *const failure::Error)
                                        -> Status {
     let error = ffi_param_ref!(error);
     error.into()
diff --git a/ffi/src/lib.rs b/ffi/src/lib.rs
index 67312a56..8c73e1b0 100644
--- a/ffi/src/lib.rs
+++ b/ffi/src/lib.rs
@@ -53,19 +53,20 @@
 //! # References
 //!
 //! When references are transferred across the FFI boundary, we use
-//! `Option<&T>`, or `Option<&mut T>`.  This takes advantage of the
-//! NULL-pointer optimization that maps `NULL` to `None`, and `*p` to
-//! `Some(&p)`.  In Rust, references always point to some object, but
-//! in C they can be `NULL`.
+//! `*const T`, or `*mut T`.  If the parameter is optional, a
+//! `Option<&T>` or `Option<&mut T>` is used.
 //!
 //! Application code must adhere to Rust's reference rules:
 //!
 //!  - Either one mutable reference or any number of immutable ones.
+//!  - All references are non-`NULL`.
 //!  - All references are valid.
 //!
 //! In this crate we enforce the second rule by asserting that all
-//! pointers handed in are non-`NULL` unless explicitly stated
-//! (e.g. destructors may be called with a `NULL` reference).
+//! pointers handed in are non-`NULL`.  There are two exceptions:
+//!
+//!   - It is explicitly stated by using `Option<&T>` or `Option<&mut T>`.
+//!   - Destructors (`sq_*_free`) may be called with `NULL`.
 //!
 //! # Lifetimes
 //!
@@ -166,10 +167,12 @@ macro_rules! ffi_param_move {
 /// Panics if called with NULL.
 macro_rules! ffi_param_ref {
     ($name:ident) => {{
-        if $name.is_none() {
+        if $name.is_null() {
             panic!("Parameter {} is NULL", stringify!($name));
         }
-        $name.unwrap()
+        unsafe {
+            &*$name
+        }
     }};
 }
 
@@ -180,10 +183,12 @@ macro_rules! ffi_param_ref {
 /// Panics if called with NULL.
 macro_rules! ffi_param_ref_mut {
     ($name:ident) => {{
-        if $name.is_none() {
+        if $name.is_null() {
             panic!("Parameter {} is NULL", stringify!($name));
         }
-        $name.unwrap()
+        unsafe {
+            &mut *$name
+        }
     }};
 }
 
diff --git a/ffi/src/net.rs b/ffi/src/net.rs
index 1506911a..177badea 100644
--- a/ffi/src/net.rs
+++ b/ffi/src/net.rs
@@ -49,7 +49,7 @@ use super::core::Context;
 ///
 /// Returns `NULL` on errors.
 #[no_mangle]
-pub extern "system" fn sq_keyserver_new(ctx: Option<&mut Context>,
+pub extern "system" fn sq_keyserver_new(ctx: *mut Context,
                                         uri: *const c_char) -> *mut KeyServer {
     let ctx = ffi_param_ref_mut!(ctx);
     let uri = unsafe {
@@ -67,7 +67,7 @@ pub extern "system" fn sq_keyserver_new(ctx: Option<&mut Context>,
 ///
 /// Returns `NULL` on errors.
 #[no_mangle]
-pub extern "system" fn sq_keyserver_with_cert(ctx: Option<&mut Context>,
+pub extern "system" fn sq_keyserver_with_cert(ctx: *mut Context,
                                               uri: *const c_char,
                                               cert: *const uint8_t,
                                               len: size_t) -> *mut KeyServer {
@@ -99,7 +99,7 @@ pub extern "system" fn sq_keyserver_with_cert(ctx: Option<&mut Context>,
 ///
 /// Returns `NULL` on errors.
 #[no_mangle]
-pub extern "system" fn sq_keyserver_sks_pool(ctx: Option<&mut Context>)
+pub extern "system" fn sq_keyserver_sks_pool(ctx: *mut Context)
                                              -> *mut KeyServer {
     let ctx = ffi_param_ref_mut!(ctx);
     fry_box!(ctx, KeyServer::sks_pool(&ctx.c))
@@ -115,9 +115,10 @@ pub extern "system" fn sq_keyserver_free(ks: *mut KeyServer) {
 ///
 /// Returns `NULL` on errors.
 #[no_mangle]
-pub extern "system" fn sq_keyserver_get(ctx: Option<&mut Context>,
-                                        ks: Option<&mut KeyServer>,
-                                        id: Option<&KeyID>) -> *mut TPK {
+pub extern "system" fn sq_keyserver_get(ctx: *mut Context,
+                                        ks: *mut KeyServer,
+                                        id: *const KeyID)
+                                        -> *mut TPK {
     let ctx = ffi_param_ref_mut!(ctx);
     let ks = ffi_param_ref_mut!(ks);
     let id = ffi_param_ref!(id);
@@ -129,9 +130,9 @@ pub extern "system" fn sq_keyserver_get(ctx: Option<&mut Context>,
 ///
 /// Returns != 0 on errors.
 #[no_mangle]
-pub extern "system" fn sq_keyserver_send(ctx: Option<&mut Context>,
-                                         ks: Option<&mut KeyServer>,
-                                         tpk: Option<&TPK>)
+pub extern "system" fn sq_keyserver_send(ctx: *mut Context,
+                                         ks: *mut KeyServer,
+                                         tpk: *const TPK)
                                          -> Status {
     let ctx = ffi_param_ref_mut!(ctx);
     let ks = ffi_param_ref_mut!(ks);
diff --git a/ffi/src/openpgp/armor.rs b/ffi/src/openpgp/armor.rs
index f426fb0a..80b0e74c 100644
--- a/ffi/src/openpgp/armor.rs
+++ b/ffi/src/openpgp/armor.rs
@@ -130,7 +130,7 @@ fn kind_to_int(kind: Option<armor::Kind>) -> c_int {
 /// }
 /// ```
 #[no_mangle]
-pub extern "system" fn sq_armor_reader_new(inner: Option<&'static mut Box<Read>>,
+pub extern "system" fn sq_armor_reader_new(inner: *mut Box<Read>,
                                            kind: c_int)
                                            -> *mut Box<Read> {
     let inner = ffi_param_ref_mut!(inner);
@@ -141,7 +141,7 @@ pub extern "system" fn sq_armor_reader_new(inner: Option<&'static mut Box<Read>>
 
 /// Creates a `Reader` from a file.
 #[no_mangle]
-pub extern "system" fn sq_armor_reader_from_file(ctx: Option<&mut Context>,
+pub extern "system" fn sq_armor_reader_from_file(ctx: *mut Context,
                                                  filename: *const c_char,
                                                  kind: c_int)
                                                  -> *mut Box<Read> {
@@ -213,9 +213,9 @@ pub extern "system" fn sq_armor_reader_kind(reader: *mut Box<Read>)
 ///
 ///   [this]: fn.sq_armor_reader_new.html
 #[no_mangle]
-pub extern "system" fn sq_armor_reader_headers(ctx: Option<&mut Context>,
+pub extern "system" fn sq_armor_reader_headers(ctx: *mut Context,
                                                reader: *mut Box<Read>,
-                                               len: Option<&mut size_t>)
+                                               len: *mut size_t)
                                                -> *mut ArmorHeader {
     let ctx = ffi_param_ref_mut!(ctx);
     let len = ffi_param_ref_mut!(len);
@@ -345,10 +345,10 @@ fn strdup(s: &str) -> *mut c_char {
 /// ```
 #[no_mangle]
 pub extern "system" fn sq_armor_writer_new
-    (ctx: Option<&mut Context>,
-     inner: Option<&'static mut Box<Write>>,
+    (ctx: *mut Context,
+     inner: *mut Box<Write>,
      kind: c_int,
-     header: Option<&ArmorHeader>,
+     header: *const ArmorHeader,
      header_len: size_t)
      -> *mut Box<Write>
 {
diff --git a/ffi/src/openpgp/fingerprint.rs b/ffi/src/openpgp/fingerprint.rs
index ee614bc4..92696601 100644
--- a/ffi/src/openpgp/fingerprint.rs
+++ b/ffi/src/openpgp/fingerprint.rs
@@ -46,7 +46,7 @@ pub extern "system" fn sq_fingerprint_free(fp: *mut Fingerprint) {
 
 /// Clones the Fingerprint.
 #[no_mangle]
-pub extern "system" fn sq_fingerprint_clone(fp: Option<&Fingerprint>)
+pub extern "system" fn sq_fingerprint_clone(fp: *const Fingerprint)
                                             -> *mut Fingerprint {
     let fp = ffi_param_ref!(fp);
     box_raw!(fp.clone())
@@ -54,7 +54,7 @@ pub extern "system" fn sq_fingerprint_clone(fp: Option<&Fingerprint>)
 
 /// Hashes the Fingerprint.
 #[no_mangle]
-pub extern "system" fn sq_fingerprint_hash(fp: Option<&Fingerprint>)
+pub extern "system" fn sq_fingerprint_hash(fp: *const Fingerprint)
                                            -> uint64_t {
     let fp = ffi_param_ref!(fp);
     let mut hasher = build_hasher();
@@ -67,7 +67,8 @@ pub extern "system" fn sq_fingerprint_hash(fp: Option<&Fingerprint>)
 /// This returns a reference to the internal buffer that is valid as
 /// long as the fingerprint is.
 #[no_mangle]
-pub extern "system" fn sq_fingerprint_as_bytes(fp: Option<&Fingerprint>, fp_len: Option<&mut size_t>)
+pub extern "system" fn sq_fingerprint_as_bytes(fp: *const Fingerprint,
+                                               fp_len: Option<&mut size_t>)
                                              -> *const uint8_t {
     let fp = ffi_param_ref!(fp);
     if let Some(p) = fp_len {
@@ -78,7 +79,7 @@ pub extern "system" fn sq_fingerprint_as_bytes(fp: Option<&Fingerprint>, fp_len:
 
 /// Converts the fingerprint to its standard representation.
 #[no_mangle]
-pub extern "system" fn sq_fingerprint_to_string(fp: Option<&Fingerprint>)
+pub extern "system" fn sq_fingerprint_to_string(fp: *const Fingerprint)
                                                 -> *mut c_char {
     let fp = ffi_param_ref!(fp);
     CString::new(fp.to_string())
@@ -88,7 +89,7 @@ pub extern "system" fn sq_fingerprint_to_string(fp: Option<&Fingerprint>)
 
 /// Converts the fingerprint to a hexadecimal number.
 #[no_mangle]
-pub extern "system" fn sq_fingerprint_to_hex(fp: Option<&Fingerprint>)
+pub extern "system" fn sq_fingerprint_to_hex(fp: *const Fingerprint)
                                              -> *mut c_char {
     let fp = ffi_param_ref!(fp);
     CString::new(fp.to_hex())
@@ -98,7 +99,7 @@ pub extern "system" fn sq_fingerprint_to_hex(fp: Option<&Fingerprint>)
 
 /// Converts the fingerprint to a key ID.
 #[no_mangle]
-pub extern "system" fn sq_fingerprint_to_keyid(fp: Option<&Fingerprint>)
+pub extern "system" fn sq_fingerprint_to_keyid(fp: *const Fingerprint)
                                                -> *mut KeyID {
     let fp = ffi_param_ref!(fp);
     Box::into_raw(Box::new(fp.to_keyid()))
@@ -106,8 +107,8 @@ pub extern "system" fn sq_fingerprint_to_keyid(fp: Option<&Fingerprint>)
 
 /// Compares Fingerprints.
 #[no_mangle]
-pub extern "system" fn sq_fingerprint_equal(a: Option<&Fingerprint>,
-                                            b: Option<&Fingerprint>)
+pub extern "system" fn sq_fingerprint_equal(a: *const Fingerprint,
+                                            b: *const Fingerprint)
                                             -> bool {
     let a = ffi_param_ref!(a);
     let b = ffi_param_ref!(b);
diff --git a/ffi/src/openpgp/keyid.rs b/ffi/src/openpgp/keyid.rs
index 2a4e2ff6..e4e716bb 100644
--- a/ffi/src/openpgp/keyid.rs
+++ b/ffi/src/openpgp/keyid.rs
@@ -57,7 +57,7 @@ pub extern "system" fn sq_keyid_free(keyid: *mut KeyID) {
 
 /// Clones the KeyID.
 #[no_mangle]
-pub extern "system" fn sq_keyid_clone(id: Option<&KeyID>)
+pub extern "system" fn sq_keyid_clone(id: *const KeyID)
                                       -> *mut KeyID {
     let id = ffi_param_ref!(id);
     box_raw!(id.clone())
@@ -65,7 +65,7 @@ pub extern "system" fn sq_keyid_clone(id: Option<&KeyID>)
 
 /// Hashes the KeyID.
 #[no_mangle]
-pub extern "system" fn sq_keyid_hash(id: Option<&KeyID>)
+pub extern "system" fn sq_keyid_hash(id: *const KeyID)
                                      -> uint64_t {
     let id = ffi_param_ref!(id);
     let mut hasher = build_hasher();
@@ -75,7 +75,7 @@ pub extern "system" fn sq_keyid_hash(id: Option<&KeyID>)
 
 /// Converts the KeyID to its standard representation.
 #[no_mangle]
-pub extern "system" fn sq_keyid_to_string(id: Option<&KeyID>)
+pub extern "system" fn sq_keyid_to_string(id: *const KeyID)
                                           -> *mut c_char {
     let id = ffi_param_ref!(id);
     CString::new(id.to_string())
@@ -85,7 +85,7 @@ pub extern "system" fn sq_keyid_to_string(id: Option<&KeyID>)
 
 /// Converts the KeyID to a hexadecimal number.
 #[no_mangle]
-pub extern "system" fn sq_keyid_to_hex(id: Option<&KeyID>)
+pub extern "system" fn sq_keyid_to_hex(id: *const KeyID)
                                        -> *mut c_char {
     let id = ffi_param_ref!(id);
     CString::new(id.to_hex())
@@ -95,8 +95,8 @@ pub extern "system" fn sq_keyid_to_hex(id: Option<&KeyID>)
 
 /// Compares KeyIDs.
 #[no_mangle]
-pub extern "system" fn sq_keyid_equal(a: Option<&KeyID>,
-                                      b: Option<&KeyID>)
+pub extern "system" fn sq_keyid_equal(a: *const KeyID,
+                                      b: *const KeyID)
                                       -> bool {
     let a = ffi_param_ref!(a);
     let b = ffi_param_ref!(b);
diff --git a/ffi/src/openpgp/mod.rs b/ffi/src/openpgp/mod.rs
index f87b24eb..859d8096 100644
--- a/ffi/src/openpgp/mod.rs
+++ b/ffi/src/openpgp/mod.rs
@@ -126,10 +126,10 @@ pub extern "system" fn sq_revocation_status_free(
 
 /// Generates a new RSA 3072 bit key with UID `primary_uid`.
 #[no_mangle]
-pub extern "system" fn sq_tsk_new(ctx: Option<&mut Context>,
+pub extern "system" fn sq_tsk_new(ctx: *mut Context,
                                   primary_uid: *const c_char,
-                                  tsk_out: Option<&mut *mut TSK>,
-                                  revocation_out: Option<&mut *mut Signature>)
+                                  tsk_out: *mut *mut TSK,
+                                  revocation_out: *mut *mut Signature)
     -> Status
 {
     let ctx = ffi_param_ref_mut!(ctx);
@@ -157,7 +157,7 @@ pub extern "system" fn sq_tsk_free(tsk: *mut TSK) {
 
 /// Returns a reference to the corresponding TPK.
 #[no_mangle]
-pub extern "system" fn sq_tsk_tpk(tsk: Option<&TSK>)
+pub extern "system" fn sq_tsk_tpk(tsk: *const TSK)
                                   -> *const TPK {
     let tsk = ffi_param_ref!(tsk);
     tsk.tpk()
@@ -174,9 +174,9 @@ pub extern "system" fn sq_tsk_into_tpk(tsk: *mut TSK)
 
 /// Serializes the TSK.
 #[no_mangle]
-pub extern "system" fn sq_tsk_serialize(ctx: Option<&mut Context>,
-                                        tsk: Option<&TSK>,
-                                        writer: Option<&mut Box<Write>>)
+pub extern "system" fn sq_tsk_serialize(ctx: *mut Context,
+                                        tsk: *const TSK,
+                                        writer: *mut Box<Write>)
                                         -> Status {
     let ctx = ffi_param_ref_mut!(ctx);
     let tsk = ffi_param_ref!(tsk);
@@ -198,7 +198,7 @@ pub extern "system" fn sq_packet_free(p: *mut Packet) {
 ///
 ///   [Section 4.3 of RFC 4880]: https://tools.ietf.org/html/rfc4880#section-4.3
 #[no_mangle]
-pub extern "system" fn sq_packet_tag(p: Option<&Packet>)
+pub extern "system" fn sq_packet_tag(p: *const Packet)
                                      -> uint8_t {
     let p = ffi_param_ref!(p);
     let tag: u8 = p.tag().into();
@@ -213,7 +213,7 @@ pub extern "system" fn sq_packet_tag(p: Option<&Packet>)
 /// into an `Packet::Unknown`.  `tag()` returns `SQ_TAG_SIGNATURE`,
 /// whereas `kind()` returns `0`.
 #[no_mangle]
-pub extern "system" fn sq_packet_kind(p: Option<&Packet>)
+pub extern "system" fn sq_packet_kind(p: *const Packet)
                                       -> uint8_t {
     let p = ffi_param_ref!(p);
     if let Some(kind) = p.kind() {
@@ -244,7 +244,7 @@ pub extern "system" fn sq_signature_to_packet(s: *mut Signature)
 /// there is no Issuer subpacket, but there is an IssuerFingerprint
 /// subpacket, this still returns NULL.
 #[no_mangle]
-pub extern "system" fn sq_signature_issuer(sig: Option<&packet::Signature>)
+pub extern "system" fn sq_signature_issuer(sig: *const packet::Signature)
                                            -> *mut KeyID {
     let sig = ffi_param_ref!(sig);
     maybe_box_raw!(sig.issuer())
@@ -257,7 +257,7 @@ pub extern "system" fn sq_signature_issuer(sig: Option<&packet::Signature>)
 /// Issuer subpacket, this still returns NULL.
 #[no_mangle]
 pub extern "system" fn sq_signature_issuer_fingerprint(
-    sig: Option<&packet::Signature>)
+    sig: *const packet::Signature)
     -> *mut Fingerprint
 {
     let sig = ffi_param_ref!(sig);
@@ -268,7 +268,7 @@ pub extern "system" fn sq_signature_issuer_fingerprint(
 /// Returns whether the KeyFlags indicates that the key can be used to
 /// make certifications.
 #[no_mangle]
-pub extern "system" fn sq_signature_can_certify(sig: Option<&packet::Signature>)
+pub extern "system" fn sq_signature_can_certify(sig: *const packet::Signature)
     -> bool
 {
     let sig = ffi_param_ref!(sig);
@@ -278,7 +278,7 @@ pub extern "system" fn sq_signature_can_certify(sig: Option<&packet::Signature>)
 /// Returns whether the KeyFlags indicates that the key can be used to
 /// make signatures.
 #[no_mangle]
-pub extern "system" fn sq_signature_can_sign(sig: Option<&packet::Signature>)
+pub extern "system" fn sq_signature_can_sign(sig: *const packet::Signature)
     -> bool
 {
     let sig = ffi_param_ref!(sig);
@@ -288,7 +288,7 @@ pub extern "system" fn sq_signature_can_sign(sig: Option<&packet::Signature>)
 /// Returns whether the KeyFlags indicates that the key can be used to
 /// encrypt data for transport.
 #[no_mangle]
-pub extern "system" fn sq_signature_can_encrypt_for_transport(sig: Option<&packet::Signature>)
+pub extern "system" fn sq_signature_can_encrypt_for_transport(sig: *const packet::Signature)
     -> bool
 {
     let sig = ffi_param_ref!(sig);
@@ -298,7 +298,7 @@ pub extern "system" fn sq_signature_can_encrypt_for_transport(sig: Option<&packe
 /// Returns whether the KeyFlags indicates that the key can be used to
 /// encrypt data at rest.
 #[no_mangle]
-pub extern "system" fn sq_signature_can_encrypt_at_rest(sig: Option<&packet::Signature>)
+pub extern "system" fn sq_signature_can_encrypt_at_rest(sig: *const packet::Signature)
     -> bool
 {
     let sig = ffi_param_ref!(sig);
@@ -308,7 +308,7 @@ pub extern "system" fn sq_signature_can_encrypt_at_rest(sig: Option<&packet::Sig
 /// Returns whether the KeyFlags indicates that the key can be used
 /// for authentication.
 #[no_mangle]
-pub extern "system" fn sq_signature_can_authenticate(sig: Option<&packet::Signature>)
+pub extern "system" fn sq_signature_can_authenticate(sig: *const packet::Signature)
     -> bool
 {
     let sig = ffi_param_ref!(sig);
@@ -318,7 +318,7 @@ pub extern "system" fn sq_signature_can_authenticate(sig: Option<&packet::Signat
 /// Returns whether the KeyFlags indicates that the key is a split
 /// key.
 #[no_mangle]
-pub extern "system" fn sq_signature_is_split_key(sig: Option<&packet::Signature>)
+pub extern "system" fn sq_signature_is_split_key(sig: *const packet::Signature)
     -> bool
 {
     let sig = ffi_param_ref!(sig);
@@ -328,7 +328,7 @@ pub extern "system" fn sq_signature_is_split_key(sig: Option<&packet::Signature>
 /// Returns whether the KeyFlags indicates that the key is a group
 /// key.
 #[no_mangle]
-p