memoryd: the crate, memoryd.toml, and listening on a socket

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

crates/memoryd/src/config.rs

@@ -0,0 +1,140 @@
+//! `memoryd` configuration: read `memoryd.toml` into a typed `Config` (M5a spec, section 11).
+//!
+//! Unknown keys are errors in every table, as in the other roles: a misspelt key that silently
+//! fell back to its default would be a setting the owner believes is set and is not.
+
+use std::path::{Path, PathBuf};
+
+use proto::DataClass;
+use serde::Deserialize;
+
+#[derive(Debug, Clone, PartialEq, Eq, Deserialize)]
+#[serde(deny_unknown_fields, default)]
+pub struct Paths {
+    pub home: PathBuf,
+}
+
+impl Default for Paths {
+    fn default() -> Self {
+        Self {
+            home: std::env::var_os("BOXMAKER_HOME")
+                .map(PathBuf::from)
+                .unwrap_or_else(|| PathBuf::from("/var/lib/boxmaker")),
+        }
+    }
+}
+
+/// `[memory]`: the starter `soul.md`, and whether identity writes wait for the owner.
+#[derive(Debug, Clone, PartialEq, Eq, Deserialize)]
+#[serde(deny_unknown_fields, default)]
+pub struct Memory {
+    /// A relative path is resolved next to the config file by `Config::load`.
+    pub soul_starter: PathBuf,
+    pub review: bool,
+}
+
+impl Default for Memory {
+    fn default() -> Self {
+        Self {
+            soul_starter: PathBuf::from("soul.md"),
+            review: false,
+        }
+    }
+}
+
+/// `[index]`: records above `max_class` are not indexed.
+#[derive(Debug, Clone, PartialEq, Eq, Deserialize)]
+#[serde(deny_unknown_fields, default)]
+pub struct Index {
+    pub max_class: DataClass,
+}
+
+impl Default for Index {
+    fn default() -> Self {
+        Self {
+            max_class: DataClass::Private,
+        }
+    }
+}
+
+/// An empty path means "the default under `home`".
+#[derive(Debug, Clone, PartialEq, Eq, Deserialize, Default)]
+#[serde(deny_unknown_fields, default)]
+pub struct Sockets {
+    #[serde(rename = "loop")]
+    pub loopd: PathBuf,
+    pub broker: PathBuf,
+    pub admin: PathBuf,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Deserialize, Default)]
+#[serde(deny_unknown_fields, default)]
+pub struct Config {
+    pub paths: Paths,
+    pub memory: Memory,
+    pub index: Index,
+    pub sockets: Sockets,
+}
+
+#[derive(Debug)]
+pub enum ConfigError {
+    Read(PathBuf, std::io::Error),
+    Parse(PathBuf, toml::de::Error),
+}
+
+impl std::fmt::Display for ConfigError {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        match self {
+            ConfigError::Read(path, err) => write!(f, "{}: {err}", path.display()),
+            ConfigError::Parse(path, err) => write!(f, "{}: {err}", path.display()),
+        }
+    }
+}
+
+impl std::error::Error for ConfigError {}
+
+impl Config {
+    pub fn parse(text: &str) -> Result<Config, toml::de::Error> {
+        toml::from_str(text)
+    }
+
+    /// Read and parse `path`; a relative `soul_starter` is taken to be next to it.
+    pub fn load(path: &Path) -> Result<Config, ConfigError> {
+        let text =
+            std::fs::read_to_string(path).map_err(|e| ConfigError::Read(path.to_path_buf(), e))?;
+        let mut config =
+            Config::parse(&text).map_err(|e| ConfigError::Parse(path.to_path_buf(), e))?;
+        if config.memory.soul_starter.is_relative() {
+            let base = path.parent().unwrap_or_else(|| Path::new("."));
+            config.memory.soul_starter = base.join(&config.memory.soul_starter);
+        }
+        Ok(config)
+    }
+
+    fn socket(&self, set: &Path, default: &str) -> PathBuf {
+        if set.as_os_str().is_empty() {
+            self.paths.home.join(default)
+        } else {
+            set.to_path_buf()
+        }
+    }
+
+    pub fn loop_socket(&self) -> PathBuf {
+        self.socket(&self.sockets.loopd, "run/loop-memory/memory.sock")
+    }
+    pub fn broker_socket(&self) -> PathBuf {
+        self.socket(&self.sockets.broker, "run/broker-memory/memory.sock")
+    }
+    pub fn admin_socket(&self) -> PathBuf {
+        self.socket(&self.sockets.admin, "run/owner-memory/admin.sock")
+    }
+    pub fn memory_dir(&self) -> PathBuf {
+        self.paths.home.join("memory")
+    }
+    pub fn index_path(&self) -> PathBuf {
+        self.paths.home.join("index/memory.sqlite3")
+    }
+    pub fn sessions_dir(&self) -> PathBuf {
+        self.paths.home.join("sessions")
+    }
+}

crates/memoryd/src/lib.rs

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+//! The memory role: the memory files, their index, and every memory tool call (M5a spec).
+
+pub mod config;
+pub mod socket;

crates/memoryd/src/main.rs

@@ -0,0 +1,33 @@
+//! `memoryd serve --config <path>`.
+
+use std::ffi::OsString;
+use std::path::PathBuf;
+use std::process::ExitCode;
+
+const USAGE: &str = "usage: memoryd serve --config <path>";
+
+fn main() -> ExitCode {
+    let args: Vec<OsString> = std::env::args_os().skip(1).collect();
+    let Some(config) = parse(&args) else {
+        eprintln!("{USAGE}");
+        return ExitCode::from(2);
+    };
+    match memoryd::config::Config::load(&config) {
+        Ok(_) => {
+            eprintln!("memoryd: not implemented");
+            ExitCode::from(2)
+        }
+        Err(e) => {
+            eprintln!("memoryd: {e}\nsee docs/runbook.md#memoryd-start-failed");
+            ExitCode::from(1)
+        }
+    }
+}
+
+/// The config path of `serve --config <path>`, or `None` for any other list.
+fn parse(args: &[OsString]) -> Option<PathBuf> {
+    match args {
+        [serve, flag, path] if serve == "serve" && flag == "--config" => Some(PathBuf::from(path)),
+        _ => None,
+    }
+}

crates/memoryd/src/socket.rs

@@ -0,0 +1,60 @@
+//! Listening on a Unix socket: the directory at 0700, a stale socket removed, the socket at 0600
+//! (M5a spec, section 7). The same steps as `brokerd`'s; no crate depends on another role's.
+
+use std::fs::{DirBuilder, Permissions};
+use std::io;
+use std::os::unix::fs::{DirBuilderExt, PermissionsExt};
+use std::os::unix::net::UnixListener;
+use std::path::Path;
+
+/// Bind one socket: prepare its directory at 0700, make it private, remove any stale socket,
+/// bind, then make the socket itself private at 0600. The error names the path.
+pub fn listen(socket: &Path) -> Result<UnixListener, String> {
+    // A socket needs a directory of its own: step 2 makes that directory 0700, which must never
+    // be `/` or a shared directory reached through a symbolic link.
+    let dir = match socket.parent() {
+        Some(parent) if parent.parent().is_some() && !parent.as_os_str().is_empty() => {
+            parent.to_path_buf()
+        }
+        _ => {
+            return Err(format!(
+                "{}: a socket needs a directory of its own, not / or none",
+                socket.display()
+            ));
+        }
+    };
+
+    // 1. The directory, at 0700.
+    DirBuilder::new()
+        .recursive(true)
+        .mode(0o700)
+        .create(&dir)
+        .map_err(|e| format!("{}: {e}", dir.display()))?;
+    // `set_permissions` follows a symbolic link, so a link would make the directory it points to
+    // private instead: refuse it.
+    let kind = std::fs::symlink_metadata(&dir)
+        .map_err(|e| format!("{}: {e}", dir.display()))?
+        .file_type();
+    if !kind.is_dir() {
+        return Err(format!(
+            "{}: is a symbolic link or not a directory; memoryd will not change its mode",
+            dir.display()
+        ));
+    }
+    // 2. Make it private, always, even when it was already there at 0755.
+    std::fs::set_permissions(&dir, Permissions::from_mode(0o700))
+        .map_err(|e| format!("{}: {e}", dir.display()))?;
+
+    // 3. A stale socket is removed; a missing one is fine.
+    match std::fs::remove_file(socket) {
+        Ok(()) => {}
+        Err(e) if e.kind() == io::ErrorKind::NotFound => {}
+        Err(e) => return Err(format!("{}: {e}", socket.display())),
+    }
+
+    // 4. Bind, then 5. make the socket private.
+    let listener = UnixListener::bind(socket).map_err(|e| format!("{}: {e}", socket.display()))?;
+    std::fs::set_permissions(socket, Permissions::from_mode(0o600))
+        .map_err(|e| format!("{}: {e}", socket.display()))?;
+    Ok(listener)
+}