Fix API eclipse-zenoh#647

include/zenoh_commons.h

@@ -3191,9 +3191,9 @@ ZENOHC_API void z_memory_layout_drop(z_moved_memory_layout_t *this_);
  */
 #if (defined(SHARED_MEMORY) && defined(UNSTABLE))
 ZENOHC_API
-void z_memory_layout_get_data(size_t *out_size,
-                              struct z_alloc_alignment_t *out_alignment,
-                              const z_loaned_memory_layout_t *this_);
+void z_memory_layout_get_data(const z_loaned_memory_layout_t *this_,
+                              size_t *out_size,
+                              struct z_alloc_alignment_t *out_alignment);
 #endif
 /**
  * Borrows Memory Layout
@@ -3931,10 +3931,19 @@ ZENOHC_API const z_loaned_shm_mut_t *z_shm_mut_loan(const z_owned_shm_mut_t *thi
 ZENOHC_API z_loaned_shm_mut_t *z_shm_mut_loan_mut(z_owned_shm_mut_t *this_);
 #endif
 /**
- * Tries to construct ZShmMut slice from ZShm slice
+ * Tries to obtain mutable SHM buffer instead of immutable one
+ * @param this: mutable SHM buffer to be initialized upon success
+ * @param that: immutable SHM buffer
+ * @param immut: immutable SHM buffer returned back to caller's side
+ * ONLY in case of Z_EUNAVAILABLE failure
+ * @return Z_OK in case of success, Z_EUNAVAILABLE in case of unsuccessful write access,
+ * Z_EINVAL if moved value is incorrect
  */
 #if (defined(SHARED_MEMORY) && defined(UNSTABLE))
-ZENOHC_API void z_shm_mut_try_from_immut(z_owned_shm_mut_t *this_, z_moved_shm_t *that);
+ZENOHC_API
+z_result_t z_shm_mut_try_from_immut(z_owned_shm_mut_t *this_,
+                                    z_moved_shm_t *that,
+                                    z_owned_shm_t *immut);
 #endif
 #if (defined(SHARED_MEMORY) && defined(UNSTABLE))
 ZENOHC_API
@@ -4833,9 +4842,9 @@ ZENOHC_API enum zc_reply_keyexpr_t zc_reply_keyexpr_default(void);
 #endif
 #if (defined(SHARED_MEMORY) && defined(UNSTABLE))
 ZENOHC_API
-z_result_t zc_shm_client_list_add_client(z_protocol_id_t id,
-                                         z_moved_shm_client_t *client,
-                                         zc_loaned_shm_client_list_t *list);
+z_result_t zc_shm_client_list_add_client(zc_loaned_shm_client_list_t *this_,
+                                         z_protocol_id_t id,
+                                         z_moved_shm_client_t *client);
 #endif
 /**
  * Deletes list of SHM Clients

src/shm/buffer/zshmmut.rs

@@ -20,26 +20,42 @@ use std::{
 use zenoh::shm::{zshmmut, ZShmMut};
 
 use crate::{
+    result,
     transmute::{LoanedCTypeRef, RustTypeRef, RustTypeRefUninit, TakeRustType},
-    z_loaned_shm_mut_t, z_moved_shm_mut_t, z_moved_shm_t, z_owned_shm_mut_t,
+    z_loaned_shm_mut_t, z_moved_shm_mut_t, z_moved_shm_t, z_owned_shm_mut_t, z_owned_shm_t,
 };
 
 decl_c_type!(
     owned(z_owned_shm_mut_t, option ZShmMut),
     loaned(z_loaned_shm_mut_t, zshmmut),
 );
 
-/// Tries to construct ZShmMut slice from ZShm slice
+/// Tries to obtain mutable SHM buffer instead of immutable one
+/// @param this: mutable SHM buffer to be initialized upon success
+/// @param that: immutable SHM buffer
+/// @param immut: immutable SHM buffer returned back to caller's side
+/// ONLY in case of Z_EUNAVAILABLE failure
+/// @return Z_OK in case of success, Z_EUNAVAILABLE in case of unsuccessful write access,
+/// Z_EINVAL if moved value is incorrect
 #[no_mangle]
 pub extern "C" fn z_shm_mut_try_from_immut(
     this: &mut MaybeUninit<z_owned_shm_mut_t>,
     that: &mut z_moved_shm_t,
-) {
-    let shm: Option<ZShmMut> = that
-        .take_rust_type()
-        .take()
-        .and_then(|val| val.try_into().ok());
-    this.as_rust_type_mut_uninit().write(shm);
+    immut: &mut MaybeUninit<z_owned_shm_t>,
+) -> result::z_result_t {
+    if let Some(shm) = that.take_rust_type() {
+        return match ZShmMut::try_from(shm) {
+            Ok(val) => {
+                this.as_rust_type_mut_uninit().write(Some(val));
+                result::Z_OK
+            }
+            Err(old) => {
+                immut.as_rust_type_mut_uninit().write(Some(old));
+                result::Z_EUNAVAILABLE
+            }
+        };
+    }
+    result::Z_EINVAL
 }
 
 /// Constructs ZShmMut slice in its gravestone value.

src/shm/client_storage/mod.rs

@@ -83,14 +83,14 @@ pub unsafe extern "C" fn zc_shm_client_list_loan_mut(
 
 #[no_mangle]
 pub extern "C" fn zc_shm_client_list_add_client(
+    this: &mut zc_loaned_shm_client_list_t,
     id: z_protocol_id_t,
     client: &mut z_moved_shm_client_t,
-    list: &mut zc_loaned_shm_client_list_t,
 ) -> z_result_t {
     let Some(client) = client.take_rust_type() else {
         return Z_EINVAL;
     };
-    list.as_rust_type_mut().push((id, client));
+    this.as_rust_type_mut().push((id, client));
     Z_OK
 }
 

src/shm/provider/types.rs

@@ -176,9 +176,9 @@ pub extern "C" fn z_memory_layout_drop(this_: &mut z_moved_memory_layout_t) {
 /// Extract data from Memory Layout
 #[no_mangle]
 pub extern "C" fn z_memory_layout_get_data(
+    this: &z_loaned_memory_layout_t,
     out_size: &mut MaybeUninit<usize>,
     out_alignment: &mut MaybeUninit<z_alloc_alignment_t>,
-    this: &z_loaned_memory_layout_t,
 ) {
     let layout = this.as_rust_type_ref();
     out_size.write(layout.size().into());

tests/z_api_shm_test.c

@@ -77,12 +77,14 @@ int test_shm_buffer(z_moved_shm_mut_t* mbuf) {
     ASSERT_CHECK(immut2);
 
     z_owned_shm_mut_t mut;
-    z_shm_mut_try_from_immut(&mut, z_move(immut2));
-    ASSERT_CHECK_ERR(immut2);
-    ASSERT_CHECK_ERR(mut);
+    ASSERT_TRUE(Z_EUNAVAILABLE == z_shm_mut_try_from_immut(&mut, z_move(immut2), &immut2));
+    ASSERT_CHECK(immut2);
+
+    z_drop(z_move(immut2));
 
-    z_shm_mut_try_from_immut(&mut, z_move(immut));
+    ASSERT_TRUE(Z_OK == z_shm_mut_try_from_immut(&mut, z_move(immut), &immut));
     ASSERT_CHECK(mut);
+    ASSERT_CHECK_ERR(immut);
 
     z_drop(z_move(mut));
     ASSERT_CHECK_ERR(mut);
@@ -189,7 +191,7 @@ void alloc_fn(struct z_owned_chunk_alloc_result_t* result, const struct z_loaned
     // check size and alignment
     size_t size = 0;
     z_alloc_alignment_t alignment;
-    z_memory_layout_get_data(&size, &alignment, layout);
+    z_memory_layout_get_data(layout, &size, &alignment);
     assert(size == 1);
     assert(alignment.pow == 0);
 
@@ -251,7 +253,7 @@ void layout_for_fn(struct z_owned_memory_layout_t* layout, void* context) {
     // check size and alignment
     size_t size = 0;
     z_alloc_alignment_t alignment;
-    z_memory_layout_get_data(&size, &alignment, z_loan(*layout));
+    z_memory_layout_get_data(z_loan(*layout), &size, &alignment);
 
     if (size != 1 || alignment.pow != 0) {
         z_memory_layout_drop(z_move(*layout));
@@ -377,7 +379,7 @@ int run_client_storage() {
     ASSERT_CHECK(client);
 
     // add client to the list
-    ASSERT_OK(zc_shm_client_list_add_client(Z_SHM_POSIX_PROTOCOL_ID, z_move(client), z_loan_mut(list)));
+    ASSERT_OK(zc_shm_client_list_add_client(z_loan_mut(list), Z_SHM_POSIX_PROTOCOL_ID, z_move(client)));
     ASSERT_CHECK_ERR(client);
 
     // create client storage from the list
@@ -426,7 +428,7 @@ int run_c_client() {
     ASSERT_CHECK(client);
 
     // add client to the list
-    ASSERT_OK(zc_shm_client_list_add_client(100500, z_move(client), z_loan_mut(list)));
+    ASSERT_OK(zc_shm_client_list_add_client(z_loan_mut(list), 100500, z_move(client)));
     ASSERT_CHECK_ERR(client);
 
     // create client storage from the list