Add NullStr type

This is a private type that is intended to be shared across wire types that
act as a null-padded fixed length container format.

This is intended to be used in a follow up PR for supporting
oxidecomputer/hubris#2463, but this is separated to
make reviewing this helper easier.

Author: jamesmunns

faux-mgs/src/main.rs

@@ -3281,27 +3281,8 @@ fn component_details_to_json(details: SpComponentDetails) -> serde_json::Value {
         Measurement(Measurement),
         LastPostCode(u32),
         PostCode(u32),
-        GpioToggleCount {
-            edge_count: u32,
-            cycles_since_last_edge: u32,
-        },
-        Pcie {
-            bar: u32,
-            offset: u32,
-            reg_result: Result<u32, u32>,
-        },
-        PmbusStatus {
-            status_word: u16,
-            status_vout: u8,
-            status_iout: u8,
-            status_temperature: u8,
-            status_cml: u8,
-            status_other: u8,
-            status_input: u8,
-            status_mfr_specific: u8,
-            status_fans_1_2: u8,
-            status_fans_3_4: u8,
-        },
+        GpioToggleCount { edge_count: u32, cycles_since_last_edge: u32 },
+        Pcie { bar: u32, offset: u32, reg_result: Result<u32, u32> },
     }
 
     #[derive(serde::Serialize)]
@@ -3344,20 +3325,6 @@ fn component_details_to_json(details: SpComponentDetails) -> serde_json::Value {
                     reg_result: p.reg_result,
                 }
             }
-            gateway_messages::ComponentDetails::PmbusStatus(stat) => {
-                ComponentDetails::PmbusStatus {
-                    status_word: stat.status_word,
-                    status_vout: stat.status_vout,
-                    status_iout: stat.status_iout,
-                    status_temperature: stat.status_temperature,
-                    status_cml: stat.status_cml,
-                    status_other: stat.status_other,
-                    status_input: stat.status_input,
-                    status_mfr_specific: stat.status_mfr_specific,
-                    status_fans_1_2: stat.status_fans_1_2,
-                    status_fans_3_4: stat.status_fans_3_4,
-                }
-            }
         })
         .collect::<Vec<_>>();
 

gateway-messages/src/lib.rs

@@ -618,71 +618,6 @@ impl TryFrom<&str> for SpComponent {
     }
 }
 
-/// Identifier for a single power rail.
-#[derive(
-    Clone, Copy, PartialEq, Eq, Hash, SerializedSize, Serialize, Deserialize,
-)]
-#[serde(transparent)]
-pub struct PowerRailName {
-    name: nullstr::NullStr<{ Self::MAX_NAME_LENGTH }>,
-}
-
-impl core::fmt::Display for PowerRailName {
-    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
-        self.name.fmt(f)
-    }
-}
-
-impl PowerRailName {
-    /// Maximum number of bytes for a Power Rail Name.
-    pub const MAX_NAME_LENGTH: usize = 32;
-
-    /// Interpret the power rail name as a human-readable string.
-    ///
-    /// Our current expectation of power rail names is that this should never
-    /// fail (i.e., we're always storing power rail names as human-readable
-    /// strings), but because we reconstitute components from network messages
-    /// we still need to check.
-    #[inline]
-    pub fn as_str(&self) -> Option<&str> {
-        self.name.as_str()
-    }
-
-    /// Interpret the power rail name as a human-readable string in a `const`
-    /// context, panicking if the string is not human readable.
-    ///
-    /// This function should only be used in const contexts when the caller
-    /// knows the component is valid (e.g., one of this type's associated
-    /// constants); for component names parsed or constructed at runtime, prefer
-    /// [`PowerRailName::as_str()`] which performs runtime validation.
-    #[inline]
-    pub const fn const_as_str(&self) -> &str {
-        self.name.const_as_str()
-    }
-
-    #[inline]
-    pub const fn from_const(val: &str) -> Self {
-        Self { name: nullstr::NullStr::from_const(val) }
-    }
-
-    #[inline]
-    pub fn id(&self) -> &[u8; Self::MAX_NAME_LENGTH] {
-        self.name.contents()
-    }
-}
-
-impl fmt::Debug for PowerRailName {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let mut debug = f.debug_struct("PowerRailName");
-        if let Some(s) = self.as_str() {
-            debug.field("name", &s);
-        } else {
-            debug.field("name", self.name.contents());
-        }
-        debug.finish()
-    }
-}
-
 /// Minimum guaranteed space for trailing data in a single packet.
 ///
 /// Depending on the [`Message`] payload, there may be more space for trailing
@@ -801,33 +736,4 @@ mod tests {
             (component, &[] as &[u8])
         );
     }
-
-    #[test]
-    fn test_human_readable_power_rail() {
-        let rail = const { PowerRailName::from_const("V0P96_NIC_VDD_A0HP") };
-        let expected_value =
-            serde_json::Value::String("V0P96_NIC_VDD_A0HP".to_string());
-
-        assert_eq!(serde_json::to_value(rail).unwrap(), expected_value);
-        assert_eq!(
-            serde_json::from_value::<PowerRailName>(expected_value).unwrap(),
-            rail
-        );
-    }
-
-    #[test]
-    fn test_non_human_readable_power_rail() {
-        let rail = const { PowerRailName::from_const("V0P96_NIC_VDD_A0HP") };
-        let expected_value = rail.name;
-
-        let mut out = [0; PowerRailName::MAX_SIZE];
-        let n = hubpack::serialize(&mut out, &rail).unwrap();
-        assert_eq!(&out[..n], expected_value.contents());
-
-        assert_eq!(
-            hubpack::deserialize::<PowerRailName>(expected_value.contents())
-                .unwrap(),
-            (rail, &[] as &[u8])
-        );
-    }
 }

gateway-messages/src/sp_to_mgs.rs

@@ -712,26 +712,6 @@ pub struct TlvPage {
     pub total: u32,
 }
 
-#[derive(
-    Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, SerializedSize,
-)]
-pub struct PmbusStatus {
-    pub status_word: u16,
-    pub status_vout: u8,
-    pub status_iout: u8,
-    pub status_temperature: u8,
-    pub status_cml: u8,
-    pub status_other: u8,
-    pub status_input: u8,
-    pub status_mfr_specific: u8,
-    pub status_fans_1_2: u8,
-    pub status_fans_3_4: u8,
-}
-
-impl PmbusStatus {
-    pub const TAG: tlv::Tag = tlv::Tag(*b"PMBS");
-}
-
 /// Types of component details that can be included in the TLV-encoded data of
 /// an [`SpResponse::ComponentDetails(_)`] message.
 ///
@@ -749,7 +729,6 @@ pub enum ComponentDetails {
     PostCode(PostCode),
     GpioToggleCount(GpioToggleCount),
     Pcie(PcieRegisterRead),
-    PmbusStatus(PmbusStatus),
 }
 
 impl ComponentDetails {
@@ -761,7 +740,6 @@ impl ComponentDetails {
             ComponentDetails::PostCode(_) => PostCode::TAG,
             ComponentDetails::GpioToggleCount(_) => GpioToggleCount::TAG,
             ComponentDetails::Pcie(_) => PcieRegisterRead::TAG,
-            ComponentDetails::PmbusStatus(_) => PmbusStatus::TAG,
         }
     }
 
@@ -791,9 +769,6 @@ impl ComponentDetails {
                 hubpack::serialize(buf, code)
             }
             ComponentDetails::Pcie(p) => hubpack::serialize(buf, p),
-            ComponentDetails::PmbusStatus(stat) => {
-                hubpack::serialize(buf, stat)
-            }
         }
     }
 }