Add platform::update::is_supported() (#320)

crates/api-desc/CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Minor
 
+- Add `platform::update::is_supported()`
 - Add `platform::update` module
 - Add `platform` module with `platform::reboot()` function
 - Call some `env_dispatch` function instead of panicking in `native`

crates/api-desc/src/platform/update.rs

@@ -24,6 +24,13 @@ pub(crate) fn new() -> Item {
     };
     let name = "update".into();
     let items = vec![
+        item! {
+            /// Whether platform update is supported.
+            fn is_supported "pus" {} -> {
+                /// 1 if supported, 0 otherwise.
+                supported: usize,
+            }
+        },
         item! {
             /// Returns the metadata of the platform.
             ///

crates/prelude/CHANGELOG.md

@@ -8,6 +8,7 @@
 
 ### Minor
 
+- Add `platform::update::is_supported()`
 - Add `platform::update` module
 - Add `platform` module with `platform::reboot()` function
 - Use `wasefire-sync` to provide `sync::Mutex`

crates/prelude/src/platform/update.rs

@@ -18,6 +18,12 @@ use alloc::boxed::Box;
 
 use wasefire_applet_api::platform::update as api;
 
+/// Returns whether platform update is supported.
+pub fn is_supported() -> bool {
+    let api::is_supported::Results { supported } = unsafe { api::is_supported() };
+    supported != 0
+}
+
 /// Returns the metadata of the platform.
 ///
 /// This typically contains the version and side (A or B) of the running platform.

crates/scheduler/CHANGELOG.md

@@ -8,6 +8,7 @@
 
 ### Minor
 
+- Support `platform::update::is_supported()`
 - Support `platform::update`
 - Support `platform` and `platform::reboot()`
 - Add more debug logging in native mode

crates/scheduler/src/call/platform/update.rs

@@ -14,20 +14,30 @@
 
 use wasefire_applet_api::platform::update::{self as api, Api};
 use wasefire_board_api::platform::update::Api as _;
-use wasefire_board_api::{self as board, Api as Board};
+use wasefire_board_api::{self as board, Api as Board, Support};
 
 use crate::applet::store::MemoryApi;
 use crate::{DispatchSchedulerCall, SchedulerCall, Trap};
 
 pub fn process<B: Board>(call: Api<DispatchSchedulerCall<B>>) {
     match call {
+        Api::IsSupported(call) => is_supported(call),
         Api::Metadata(call) => metadata(call),
         Api::Initialize(call) => initialize(call),
         Api::Process(call) => process_(call),
         Api::Finalize(call) => finalize(call),
     }
 }
 
+fn is_supported<B: Board>(call: SchedulerCall<B, api::is_supported::Sig>) {
+    let api::is_supported::Params {} = call.read();
+    let results = try {
+        let supported = board::platform::Update::<B>::SUPPORT as u32;
+        api::is_supported::Results { supported: supported.into() }
+    };
+    call.reply(results)
+}
+
 fn metadata<B: Board>(mut call: SchedulerCall<B, api::metadata::Sig>) {
     let api::metadata::Params { ptr: ptr_ptr, len: len_ptr } = call.read();
     let scheduler = call.scheduler();

examples/assemblyscript/api.ts

@@ -691,6 +691,12 @@
   // All operations are abstract over the update content such that they can work on all
   // platforms. In particular, chunks and errors are platform-specific. Applets with
   // knowledge about their platform may actually inspect that content for additional checks.
+    // Whether platform update is supported.
+    @external("env", "pus")
+    export declare function platform_update_is_supported(
+    // 1 if supported, 0 otherwise.
+    ): usize
+
     // Returns the metadata of the platform.
     //
     // This typically contains the version and side (A or B) of the running platform.

examples/rust/update/src/lib.rs

@@ -16,6 +16,7 @@
 wasefire::applet!();
 
 fn main() {
+    assert!(platform::update::is_supported());
     let metadata = platform::update::metadata().unwrap();
     debug!("{metadata:02x?}");
     let serial = usb::serial::UsbSerial;