showfile: serve a text file as its own command (e.g. /RULES), config-driven like aliases

echoircd.conf.example

@@ -117,6 +117,10 @@ amu_target    = both
 # hidewhois_hide_server = yes  # hide 312
 # hidewhois_hide_idle = yes    # hide 317
 # hidewhois_hide_secure = yes  # hide 671
+# --- showfile (m_showfile): serve a text file as its own command. One line per
+#     file: `showfile = <COMMAND> <path>`. The file is read fresh each use, so
+#     edits show without a rehash. e.g. make /RULES stream a rules file:
+# showfile = RULES /etc/echoircd/rules.txt
 # --- geoip (m_geo_maxmind): native MaxMind .mmdb country lookup. Enables the
 #     G:<cc> ban extban (e.g. +b G:CN,RU), the oper GEOIP <nick|ip> command and
 #     a country line in WHOIS (opers). Point at a GeoLite2-Country.mmdb file:

src/ircd.rs

@@ -283,6 +283,11 @@ impl Ircd {
 
         let Some(handler) = self.commands.get(cmd) else {
             if registered {
+                // showfile (m_showfile): config `showfile = <CMD> <path>` streams a
+                // text file as its own command (e.g. /RULES), like a config-named alias.
+                if crate::modules::showfile::maybe_show(&mut self.server, uid, cmd) {
+                    return;
+                }
                 // command aliases (m_alias): config `alias = <CMD> <target-nick>`
                 // e.g. `alias = NS NickServ` makes `/NS help` -> PRIVMSG NickServ :help
                 if let Some(target) = self.server.conf_all("alias").iter().find_map(|line| {

src/modules/mod.rs

@@ -48,6 +48,7 @@ pub mod rpc;
 pub mod securelist;
 pub mod securitygroups;
 pub mod serverban;
+pub mod showfile;
 pub mod snoop;
 pub mod tline;
 pub mod whoisport;

src/modules/showfile.rs

@@ -0,0 +1,41 @@
+//! showfile — serve a text file as its own command (InspIRCd's `m_showfile`).
+//! Config, one line per file:
+//!
+//! ```text
+//! showfile = <COMMAND> <path>      # e.g.  showfile = RULES /etc/echoircd/rules.txt
+//! ```
+//!
+//! makes `/RULES` stream the file to the client. Dispatched from the same place as
+//! command aliases (an unknown, config-named command), so no static registration is
+//! needed. The file is read fresh on each use, so edits show without a REHASH.
+//! Original native Rust.
+
+use crate::server::Server;
+use crate::Uid;
+
+/// If `cmd` names a configured `showfile`, stream that file to `uid` (one NOTICE
+/// per line) and return `true`. Returns `false` if no showfile matches `cmd`, so
+/// the caller can fall through to the normal unknown-command handling.
+pub fn maybe_show(s: &mut Server, uid: Uid, cmd: &str) -> bool {
+    let path = s.conf_all("showfile").iter().find_map(|line| {
+        let (name, path) = line.split_once(char::is_whitespace)?;
+        name.eq_ignore_ascii_case(cmd)
+            .then(|| path.trim().to_string())
+    });
+    let Some(path) = path else {
+        return false;
+    };
+    let nick = s.users.get(&uid).map(|u| u.nick.clone()).unwrap_or_default();
+    match std::fs::read_to_string(&path) {
+        Ok(body) => {
+            for line in body.lines() {
+                s.send(uid, format!(":{} NOTICE {nick} :{line}", s.name));
+            }
+        }
+        Err(_) => s.send(
+            uid,
+            format!(":{} NOTICE {nick} :*** {cmd}: file not available.", s.name),
+        ),
+    }
+    true
+}