feat: add log-server (ring buffer) and permission-manager (grant/revoke/check) system servers

crates/servers/log-server/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "log-server"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+types = { workspace = true }
+server-framework = { workspace = true }

crates/servers/log-server/src/lib.rs

@@ -0,0 +1,8 @@
+#![no_std]
+
+pub mod protocol;
+pub mod server;
+
+#[cfg(test)]
+#[path = "tests/mod.rs"]
+mod tests;

crates/servers/log-server/src/protocol.rs

@@ -0,0 +1,99 @@
+use server_framework::{Decode, Encode};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum LogLevel {
+    Error,
+    Warn,
+    Info,
+    Debug,
+}
+
+#[derive(Debug, PartialEq)]
+pub enum LogRequest {
+    Write { level: LogLevel, tag: u16, payload: usize },
+    GetCount,
+    GetEntry { index: usize },
+}
+
+#[derive(Debug, PartialEq)]
+pub enum LogResponse {
+    Ok,
+    Count(usize),
+    Entry { level: LogLevel, tag: u16, payload: usize },
+    NotFound,
+}
+
+fn encode_level(level: LogLevel) -> usize {
+    match level {
+        LogLevel::Error => 0,
+        LogLevel::Warn => 1,
+        LogLevel::Info => 2,
+        LogLevel::Debug => 3,
+    }
+}
+
+fn decode_level(v: usize) -> Option<LogLevel> {
+    match v {
+        0 => Some(LogLevel::Error),
+        1 => Some(LogLevel::Warn),
+        2 => Some(LogLevel::Info),
+        3 => Some(LogLevel::Debug),
+        _ => None,
+    }
+}
+
+impl Encode for LogRequest {
+    fn encode(&self) -> [usize; 4] {
+        match self {
+            LogRequest::Write { level, tag, payload } => {
+                [0, encode_level(*level) | ((*tag as usize) << 8), *payload, 0]
+            }
+            LogRequest::GetCount => [1, 0, 0, 0],
+            LogRequest::GetEntry { index } => [2, *index, 0, 0],
+        }
+    }
+}
+
+impl Decode for LogRequest {
+    fn decode(words: [usize; 4]) -> Option<Self> {
+        match words[0] {
+            0 => {
+                let level = decode_level(words[1] & 0xFF)?;
+                let tag = ((words[1] >> 8) & 0xFFFF) as u16;
+                Some(LogRequest::Write { level, tag, payload: words[2] })
+            }
+            1 => Some(LogRequest::GetCount),
+            2 => Some(LogRequest::GetEntry { index: words[1] }),
+            _ => None,
+        }
+    }
+}
+
+impl Encode for LogResponse {
+    fn encode(&self) -> [usize; 4] {
+        match self {
+            LogResponse::Ok => [0, 0, 0, 0],
+            LogResponse::Count(n) => [1, *n, 0, 0],
+            LogResponse::Entry { level, tag, payload } => {
+                [2, encode_level(*level) | ((*tag as usize) << 8), *payload, 0]
+            }
+            LogResponse::NotFound => [3, 0, 0, 0],
+        }
+    }
+}
+
+impl Decode for LogResponse {
+    fn decode(words: [usize; 4]) -> Option<Self> {
+        match words[0] {
+            0 => Some(LogResponse::Ok),
+            1 => Some(LogResponse::Count(words[1])),
+            2 => {
+                let level = decode_level(words[1] & 0xFF)?;
+                let tag = ((words[1] >> 8) & 0xFFFF) as u16;
+                Some(LogResponse::Entry { level, tag, payload: words[2] })
+            }
+            3 => Some(LogResponse::NotFound),
+            _ => None,
+        }
+    }
+}

crates/servers/log-server/src/server.rs

@@ -0,0 +1,68 @@
+use server_framework::Server;
+
+use crate::protocol::{LogLevel, LogRequest, LogResponse};
+
+const MAX_ENTRIES: usize = 128;
+
+struct LogEntry {
+    level: LogLevel,
+    tag: u16,
+    payload: usize,
+}
+
+pub struct LogServer {
+    entries: [Option<LogEntry>; MAX_ENTRIES],
+    count: usize,
+    write_pos: usize,
+}
+
+impl LogServer {
+    pub fn new() -> Self {
+        Self {
+            entries: [const { None }; MAX_ENTRIES],
+            count: 0,
+            write_pos: 0,
+        }
+    }
+
+    pub fn count(&self) -> usize {
+        self.count
+    }
+}
+
+impl Server for LogServer {
+    type Request = LogRequest;
+    type Response = LogResponse;
+
+    fn handle(&mut self, request: LogRequest) -> LogResponse {
+        match request {
+            LogRequest::Write { level, tag, payload } => {
+                self.entries[self.write_pos] = Some(LogEntry { level, tag, payload });
+                self.write_pos = (self.write_pos + 1) % MAX_ENTRIES;
+                if self.count < MAX_ENTRIES {
+                    self.count += 1;
+                }
+                LogResponse::Ok
+            }
+            LogRequest::GetCount => LogResponse::Count(self.count),
+            LogRequest::GetEntry { index } => {
+                if index >= self.count {
+                    return LogResponse::NotFound;
+                }
+                let actual = if self.count < MAX_ENTRIES {
+                    index
+                } else {
+                    (self.write_pos + index) % MAX_ENTRIES
+                };
+                match &self.entries[actual] {
+                    Some(entry) => LogResponse::Entry {
+                        level: entry.level,
+                        tag: entry.tag,
+                        payload: entry.payload,
+                    },
+                    None => LogResponse::NotFound,
+                }
+            }
+        }
+    }
+}

crates/servers/log-server/src/tests/mod.rs

@@ -0,0 +1,2 @@
+mod protocol;
+mod server;

crates/servers/log-server/src/tests/protocol.rs

@@ -0,0 +1,39 @@
+use crate::protocol::*;
+use server_framework::{Decode, Encode};
+
+#[test]
+fn write_request_roundtrip() {
+    let req = LogRequest::Write { level: LogLevel::Error, tag: 42, payload: 0xDEAD };
+    assert_eq!(LogRequest::decode(req.encode()), Some(req));
+}
+
+#[test]
+fn get_count_roundtrip() {
+    let req = LogRequest::GetCount;
+    assert_eq!(LogRequest::decode(req.encode()), Some(req));
+}
+
+#[test]
+fn get_entry_roundtrip() {
+    let req = LogRequest::GetEntry { index: 7 };
+    assert_eq!(LogRequest::decode(req.encode()), Some(req));
+}
+
+#[test]
+fn entry_response_roundtrip() {
+    let resp = LogResponse::Entry { level: LogLevel::Warn, tag: 10, payload: 123 };
+    assert_eq!(LogResponse::decode(resp.encode()), Some(resp));
+}
+
+#[test]
+fn all_levels_roundtrip() {
+    for level in [LogLevel::Error, LogLevel::Warn, LogLevel::Info, LogLevel::Debug] {
+        let req = LogRequest::Write { level, tag: 0, payload: 0 };
+        assert_eq!(LogRequest::decode(req.encode()), Some(req));
+    }
+}
+
+#[test]
+fn invalid_request_returns_none() {
+    assert!(LogRequest::decode([99, 0, 0, 0]).is_none());
+}

crates/servers/log-server/src/tests/server.rs

@@ -0,0 +1,43 @@
+use crate::protocol::*;
+use crate::server::LogServer;
+use server_framework::Server;
+
+#[test]
+fn empty_server_has_zero_count() {
+    let mut server = LogServer::new();
+    let resp = server.handle(LogRequest::GetCount);
+    assert_eq!(resp, LogResponse::Count(0));
+}
+
+#[test]
+fn write_increments_count() {
+    let mut server = LogServer::new();
+    server.handle(LogRequest::Write { level: LogLevel::Info, tag: 0, payload: 1 });
+    server.handle(LogRequest::Write { level: LogLevel::Info, tag: 0, payload: 2 });
+    let resp = server.handle(LogRequest::GetCount);
+    assert_eq!(resp, LogResponse::Count(2));
+}
+
+#[test]
+fn get_entry_returns_written_data() {
+    let mut server = LogServer::new();
+    server.handle(LogRequest::Write { level: LogLevel::Error, tag: 5, payload: 0xBEEF });
+    let resp = server.handle(LogRequest::GetEntry { index: 0 });
+    assert_eq!(resp, LogResponse::Entry { level: LogLevel::Error, tag: 5, payload: 0xBEEF });
+}
+
+#[test]
+fn get_entry_out_of_range_returns_not_found() {
+    let mut server = LogServer::new();
+    let resp = server.handle(LogRequest::GetEntry { index: 0 });
+    assert_eq!(resp, LogResponse::NotFound);
+}
+
+#[test]
+fn ring_buffer_wraps() {
+    let mut server = LogServer::new();
+    for i in 0..200 {
+        server.handle(LogRequest::Write { level: LogLevel::Debug, tag: 0, payload: i });
+    }
+    assert_eq!(server.count(), 128);
+}