Use new NullStr based SpComponent (#2545)

Codegen impl changes necessary to support
oxidecomputer/management-gateway-service#496.

Author: jamesmunns

Cargo.lock

@@ -129,8 +129,21 @@ impl Inventory {
         if !device.sensors.is_empty() {
             capabilities |= DeviceCapabilities::HAS_MEASUREMENT_CHANNELS;
         }
+
+        // NOTE: the `from_bstr_unchecked` method expects that:
+        //
+        // 1. The given bytes contain utf-8 data
+        // 2. The given slice is <= SpComponent::MAX_ID_LENGTH
+        //
+        // Since we pass the bytes of a `str` (always good utf-8!), and our
+        // `str`s are built (and length-checked) at compile time, use of this
+        // method is justified. You don't see an unsafe block here, because
+        // SpComponent can be received over the wire, so even if we violated
+        // the rules above, there would be no potential soundness concerns.
+        let component = SpComponent::from_bstr_unchecked(device.id.as_bytes());
+
         DeviceDescription {
-            component: SpComponent { id: device.id },
+            component,
             device: device.device,
             description: device.description,
             capabilities,
@@ -178,8 +191,13 @@ impl TryFrom<&'_ SpComponent> for Index {
     type Error = SpError;
 
     fn try_from(component: &'_ SpComponent) -> Result<Self, Self::Error> {
+        // TODO(AJM): implement PartialEq/PartialOrd for `SpComponent` et. al,
+        // then make this nicer. We'll want this for some follow-up PMBus
+        // changes as well.
         if let Ok(entry_idx) = task_validate_api::DEVICE_INDICES_BY_SORTED_ID
-            .binary_search_by_key(&component.id, |&(id, _)| id)
+            .binary_search_by_key(&component.as_bstr(), |&(id, _)| {
+                id.as_bytes()
+            })
         {
             let &(_, index) = task_validate_api::DEVICE_INDICES_BY_SORTED_ID
                 .get(entry_idx)

task/control-plane-agent/src/inventory.rs

@@ -78,7 +78,7 @@ impl ComponentUpdater for RotUpdate {
             .map_err(SpError::OtherComponentUpdateInProgress)?;
 
         // Which target are we updating?
-        ringbuf_entry!(Trace::Target(update.component.id[0], update.slot));
+        ringbuf_entry!(Trace::Target(update.component.id()[0], update.slot));
         let target = match (update.component, update.slot) {
             (SpComponent::ROT, 0) => UpdateTarget::ImageA,
             (SpComponent::ROT, 1) => UpdateTarget::ImageB,

task/control-plane-agent/src/update/rot.rs

@@ -63,10 +63,10 @@ fn write_pub_device_descriptions() -> anyhow::Result<()> {
         writeln!(file, "    DeviceDescription {{")?;
         writeln!(file, "        device: {:?},", dev.device)?;
         writeln!(file, "        description: {:?},", dev.description)?;
-        if let Some(id) = dev.device_id {
-            if let Ok(component) = SpComponent::try_from(id.as_ref()) {
-                writeln!(file, "        id: {:?},", component.id)?;
-                if id2idx.insert(component.id, idx).is_some() {
+        if let Some(id) = dev.device_id.as_ref() {
+            if id.len() <= SpComponent::MAX_ID_LENGTH {
+                writeln!(file, "        id: \"{id}\",")?;
+                if id2idx.insert(id.to_string(), idx).is_some() {
                     println!("cargo::error=duplicate device id {id:?}",);
                     duplicate_ids += 1;
                 }
@@ -106,11 +106,11 @@ fn write_pub_device_descriptions() -> anyhow::Result<()> {
 
     writeln!(
         file,
-        "pub static DEVICE_INDICES_BY_SORTED_ID: [([u8; MAX_ID_LENGTH], usize); {}] = [",
+        "pub static DEVICE_INDICES_BY_SORTED_ID: [(&str, usize); {}] = [",
         id2idx.len()
     )?;
     for (id, idx) in id2idx {
-        writeln!(file, "    ({id:?}, {idx}),")?;
+        writeln!(file, "    (\"{id}\", {idx}),")?;
     }
     writeln!(file, "];")?;
 

task/validate-api/build.rs

@@ -74,7 +74,7 @@ pub struct DeviceDescription {
     pub device: &'static str,
     pub description: &'static str,
     pub sensors: &'static [SensorDescription],
-    pub id: [u8; MAX_ID_LENGTH],
+    pub id: &'static str,
     pub is_pmbus: bool,
 }