cli: Add `rad node logs` sub-command

Prints the last `n` lines and follows the log.

radicle-cli/src/commands/node.rs

@@ -24,24 +24,31 @@ pub const HELP: Help = Help {
     usage: r#"
 Usage
 
-    rad node events [<option>...]
     rad node status [<option>...]
-    rad node start [--daemon|-d] [<option>...] [-- <node-option>...]
+    rad node start [--daemon | -d] [<option>...] [-- <node-option>...]
     rad node stop [<option>...]
+    rad node logs [-n <lines>]
     rad node connect <nid> <addr> [<option>...]
     rad node routing [--rid <rid>] [--nid <nid>] [--json] [<option>...]
-    rad node tracking [--repos|--nodes] [<option>...]
+    rad node tracking [--repos | --nodes] [<option>...]
+    rad node events [<option>...]
 
     For `<node-option>` see `radicle-node --help`.
 
-Options
+Routing options
+
+    --rid <rid>     Show the routing table entries for the given RID
+    --nid <nid>     Show the routing table entries for the given NID
+    --json          Output the routing table as json
+
+Tracking options
 
-    --help          Print help
     --repos         Show the tracked repositories table
     --nodes         Show the tracked nodes table
-    --rid           Show the routing table entries for the given RID
-    --nid           Show the routing table entries for the given NID
-    --json          Output the routing table as json
+
+General options
+
+    --help          Print help
 "#,
 };
 
@@ -64,6 +71,9 @@ pub enum Operation {
         daemon: bool,
         options: Vec<OsString>,
     },
+    Logs {
+        lines: usize,
+    },
     Status,
     Stop,
     Tracking {
@@ -83,6 +93,7 @@ pub enum OperationName {
     Connect,
     Events,
     Routing,
+    Logs,
     Start,
     #[default]
     Status,
@@ -103,6 +114,7 @@ impl Args for Options {
         let mut rid: Option<Id> = None;
         let mut json: bool = false;
         let mut addr: Option<Address> = None;
+        let mut lines: usize = 10;
 
         while let Some(arg) = parser.next()? {
             match arg {
@@ -112,6 +124,7 @@ impl Args for Options {
                 Value(val) if op.is_none() => match val.to_string_lossy().as_ref() {
                     "connect" => op = Some(OperationName::Connect),
                     "events" => op = Some(OperationName::Events),
+                    "logs" => op = Some(OperationName::Logs),
                     "routing" => op = Some(OperationName::Routing),
                     "start" => op = Some(OperationName::Start),
                     "status" => op = Some(OperationName::Status),
@@ -151,6 +164,9 @@ impl Args for Options {
                 Long("daemon") | Short('d') if matches!(op, Some(OperationName::Start)) => {
                     daemon = true;
                 }
+                Short('n') if matches!(op, Some(OperationName::Logs)) => {
+                    lines = parser.value()?.parse()?;
+                }
                 Value(val) if matches!(op, Some(OperationName::Start)) => {
                     options.push(val);
                 }
@@ -165,6 +181,7 @@ impl Args for Options {
             },
             OperationName::Events => Operation::Events,
             OperationName::Routing => Operation::Routing { rid, nid, json },
+            OperationName::Logs => Operation::Logs { lines },
             OperationName::Start => Operation::Start { daemon, options },
             OperationName::Status => Operation::Status,
             OperationName::Stop => Operation::Stop,
@@ -193,6 +210,7 @@ pub fn run(options: Options, ctx: impl term::Context) -> anyhow::Result<()> {
                 radicle::node::routing::Table::reader(profile.home.node().join(ROUTING_DB_FILE))?;
             routing::run(&store, rid, nid, json)?;
         }
+        Operation::Logs { lines } => control::logs(lines)?,
         Operation::Start { daemon, options } => control::start(daemon, options)?,
         Operation::Status => {
             let node = Node::new(profile.socket());

radicle-cli/src/commands/node/control.rs

@@ -1,6 +1,8 @@
 use std::ffi::OsString;
-use std::fs::OpenOptions;
-use std::process;
+use std::fs::{File, OpenOptions};
+use std::io::{BufRead, BufReader, Read, Seek, SeekFrom};
+use std::time::Duration;
+use std::{process, thread};
 
 use radicle::node::{Address, Handle as _, NodeId};
 use radicle::Node;
@@ -41,6 +43,45 @@ pub fn stop(node: Node) -> anyhow::Result<()> {
     Ok(())
 }
 
+pub fn logs(lines: usize) -> anyhow::Result<()> {
+    let home = radicle::profile::home()?;
+    let logs = home.node().join("node.log");
+
+    let mut file = BufReader::new(File::open(logs)?);
+    file.seek(SeekFrom::End(-1))?;
+
+    let mut tail = Vec::new();
+    let mut nlines = 0;
+
+    for i in (0..=file.stream_position()?).rev() {
+        let mut buf = [0; 1];
+        file.seek(SeekFrom::Start(i))?;
+        file.read_exact(&mut buf)?;
+
+        if buf[0] == b'\n' {
+            nlines += 1;
+        }
+        if nlines > lines {
+            break;
+        }
+        tail.push(buf[0]);
+    }
+    tail.reverse();
+
+    print!("{}", String::from_utf8_lossy(&tail));
+
+    file.seek(SeekFrom::End(0))?;
+    loop {
+        let mut line = String::new();
+        let len = file.read_line(&mut line)?;
+        if len == 0 {
+            thread::sleep(Duration::from_millis(250));
+        } else {
+            print!("{line}");
+        }
+    }
+}
+
 pub fn connect(node: &mut Node, nid: NodeId, addr: Address) -> anyhow::Result<()> {
     let spinner = term::spinner(format!(
         "Connecting to {}@{addr}...",