multicall: cleanup; modularize

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I658f22fdf983777354a5beb32df631916a6a6964

src/multicall/wl_paste.rs

@@ -0,0 +1,454 @@
+// https://wayland.freedesktop.org/docs/html/apa.html#protocol-spec-wl_data_device
+// https://docs.rs/wl-clipboard-rs/latest/wl_clipboard_rs
+// https://github.com/YaLTeR/wl-clipboard-rs/blob/master/wl-clipboard-rs-tools/src/bin/wl_paste.rs
+use std::{
+  collections::hash_map::DefaultHasher,
+  hash::{Hash, Hasher},
+  io::{self, Read, Write},
+  process::{Command, Stdio},
+  sync::{Arc, Mutex},
+  thread,
+  time::{Duration, Instant},
+};
+
+use clap::{ArgAction, Parser};
+use color_eyre::eyre::{Context, Result, bail};
+use wl_clipboard_rs::paste::{
+  ClipboardType as PasteClipboardType,
+  Error as PasteError,
+  MimeType as PasteMimeType,
+  Seat as PasteSeat,
+  get_contents,
+  get_mime_types,
+};
+
+// Watch mode timing constants
+const WATCH_POLL_INTERVAL_MS: u64 = 500;
+const WATCH_DEBOUNCE_INTERVAL_MS: u64 = 1000;
+
+// Maximum clipboard content size to prevent memory exhaustion (100MB)
+const MAX_CLIPBOARD_SIZE: usize = 100 * 1024 * 1024;
+
+#[derive(Parser, Debug)]
+#[command(
+  name = "wl-paste",
+  about = "Paste clipboard contents on Wayland.",
+  version,
+  disable_help_subcommand = true
+)]
+struct WlPasteArgs {
+  /// List the offered MIME types instead of pasting
+  #[arg(short = 'l', long = "list-types", action = ArgAction::SetTrue)]
+  list_types: bool,
+
+  /// Use the "primary" clipboard
+  #[arg(short = 'p', long = "primary", action = ArgAction::SetTrue)]
+  primary: bool,
+
+  /// Do not append a newline character
+  #[arg(short = 'n', long = "no-newline", action = ArgAction::SetTrue)]
+  no_newline: bool,
+
+  /// Pick the seat to work with
+  #[arg(short = 's', long = "seat")]
+  seat: Option<String>,
+
+  /// Request the given MIME type instead of inferring the MIME type
+  #[arg(short = 't', long = "type")]
+  mime_type: Option<String>,
+
+  /// Enable verbose logging
+  #[arg(short = 'v', long = "verbose", action = ArgAction::Count)]
+  verbose: u8,
+
+  /// Watch for clipboard changes and run a command
+  #[arg(short = 'w', long = "watch")]
+  watch: Option<Vec<String>>,
+}
+
+fn get_paste_mime_type(mime_arg: Option<&str>) -> PasteMimeType {
+  match mime_arg {
+    None | Some("text" | "autodetect") => PasteMimeType::Text,
+    Some(other) => PasteMimeType::Specific(other),
+  }
+}
+
+fn handle_list_types(
+  clipboard: PasteClipboardType,
+  seat: PasteSeat,
+) -> Result<()> {
+  match get_mime_types(clipboard, seat) {
+    Ok(types) => {
+      for mime_type in types {
+        println!("{mime_type}");
+      }
+
+      #[allow(clippy::needless_return)]
+      return Ok(());
+    },
+    Err(PasteError::NoSeats) => {
+      bail!("no seats available (is a Wayland compositor running?)");
+    },
+    Err(e) => {
+      bail!("failed to list types: {e}");
+    },
+  }
+}
+
+fn handle_watch_mode(
+  args: &WlPasteArgs,
+  clipboard: PasteClipboardType,
+  seat: PasteSeat,
+) -> Result<()> {
+  let watch_args = args.watch.as_ref().unwrap();
+  if watch_args.is_empty() {
+    bail!("--watch requires a command to run");
+  }
+
+  log::info!("starting clipboard watch mode");
+
+  // Shared state for tracking last content and shutdown signal
+  let last_content_hash = Arc::new(Mutex::new(None::<u64>));
+  let shutdown = Arc::new(Mutex::new(false));
+
+  // Set up signal handler for graceful shutdown
+  let shutdown_clone = shutdown.clone();
+  ctrlc::set_handler(move || {
+    log::info!("received shutdown signal, stopping watch mode");
+    if let Ok(mut shutdown_guard) = shutdown_clone.lock() {
+      *shutdown_guard = true;
+    } else {
+      log::error!("failed to acquire shutdown lock in signal handler");
+    }
+  })
+  .context("failed to set signal handler")?;
+
+  let poll_interval = Duration::from_millis(WATCH_POLL_INTERVAL_MS);
+  let debounce_interval = Duration::from_millis(WATCH_DEBOUNCE_INTERVAL_MS);
+  let mut last_change_time = Instant::now();
+
+  loop {
+    // Check for shutdown signal
+    match shutdown.lock() {
+      Ok(shutdown_guard) => {
+        if *shutdown_guard {
+          log::info!("shutting down watch mode");
+          break Ok(());
+        }
+      },
+      Err(e) => {
+        log::error!("failed to acquire shutdown lock: {e}");
+        thread::sleep(poll_interval);
+        continue;
+      },
+    }
+
+    // Get current clipboard content
+    let current_hash = match get_clipboard_content_hash(clipboard, seat) {
+      Ok(hash) => hash,
+      Err(e) => {
+        log::error!("failed to get clipboard content hash: {e}");
+        thread::sleep(poll_interval);
+        continue;
+      },
+    };
+
+    // Check if content has changed
+    match last_content_hash.lock() {
+      Ok(mut last_hash_guard) => {
+        let changed = *last_hash_guard != Some(current_hash);
+        if changed {
+          let now = Instant::now();
+
+          // Debounce rapid changes
+          if now.duration_since(last_change_time) >= debounce_interval {
+            *last_hash_guard = Some(current_hash);
+            last_change_time = now;
+            drop(last_hash_guard); // Release lock before spawning command
+
+            log::info!("clipboard content changed, executing watch command");
+
+            // Execute the watch command
+            if let Err(e) = execute_watch_command(watch_args, clipboard, seat) {
+              log::error!("failed to execute watch command: {e}");
+              // Continue watching even if command fails
+            }
+          }
+        }
+        changed
+      },
+      Err(e) => {
+        log::error!("failed to acquire last_content_hash lock: {e}");
+        thread::sleep(poll_interval);
+        continue;
+      },
+    };
+
+    thread::sleep(poll_interval);
+  }
+}
+
+fn get_clipboard_content_hash(
+  clipboard: PasteClipboardType,
+  seat: PasteSeat,
+) -> Result<u64> {
+  match get_contents(clipboard, seat, PasteMimeType::Text) {
+    Ok((mut reader, _types)) => {
+      let mut content = Vec::new();
+      let mut temp_buffer = [0; 8192];
+
+      loop {
+        let bytes_read = reader
+          .read(&mut temp_buffer)
+          .context("failed to read clipboard content")?;
+
+        if bytes_read == 0 {
+          break;
+        }
+
+        if content.len() + bytes_read > MAX_CLIPBOARD_SIZE {
+          bail!(
+            "clipboard content exceeds maximum size of {} bytes",
+            MAX_CLIPBOARD_SIZE
+          );
+        }
+
+        content.extend_from_slice(&temp_buffer[..bytes_read]);
+      }
+
+      let mut hasher = DefaultHasher::new();
+      content.hash(&mut hasher);
+      Ok(hasher.finish())
+    },
+    Err(PasteError::ClipboardEmpty) => {
+      Ok(0) // Empty clipboard has hash 0
+    },
+    Err(e) => bail!("clipboard error: {e}"),
+  }
+}
+
+/// Validate command name to prevent command injection
+fn validate_command_name(cmd: &str) -> Result<()> {
+  if cmd.is_empty() {
+    bail!("command name cannot be empty");
+  }
+
+  // Reject commands with shell metacharacters or path traversal
+  if cmd.contains(|c| {
+    ['|', '&', ';', '$', '`', '(', ')', '<', '>', '"', '\'', '\\'].contains(&c)
+  }) {
+    bail!("command contains invalid characters: {cmd}");
+  }
+
+  // Reject absolute paths and relative path traversal
+  if cmd.starts_with('/') || cmd.contains("..") {
+    bail!("command paths are not allowed: {cmd}");
+  }
+
+  Ok(())
+}
+
+/// Set environment variable safely with validation
+fn set_clipboard_state_env(has_content: bool) -> Result<()> {
+  let value = if has_content { "data" } else { "nil" };
+
+  // Validate the environment variable value
+  if !matches!(value, "data" | "nil") {
+    bail!("invalid clipboard state value: {value}");
+  }
+
+  // Safe to set environment variable with validated, known-safe value
+  unsafe {
+    std::env::set_var("STASH_CLIPBOARD_STATE", value);
+  }
+  Ok(())
+}
+
+fn execute_watch_command(
+  watch_args: &[String],
+  clipboard: PasteClipboardType,
+  seat: PasteSeat,
+) -> Result<()> {
+  if watch_args.is_empty() {
+    bail!("watch command cannot be empty");
+  }
+
+  // Validate command name for security
+  validate_command_name(&watch_args[0])?;
+
+  let mut cmd = Command::new(&watch_args[0]);
+  if watch_args.len() > 1 {
+    cmd.args(&watch_args[1..]);
+  }
+
+  // Get clipboard content and pipe it to the command
+  match get_contents(clipboard, seat, PasteMimeType::Text) {
+    Ok((mut reader, _types)) => {
+      let mut content = Vec::new();
+      let mut temp_buffer = [0; 8192];
+
+      loop {
+        let bytes_read = reader
+          .read(&mut temp_buffer)
+          .context("failed to read clipboard")?;
+
+        if bytes_read == 0 {
+          break;
+        }
+
+        if content.len() + bytes_read > MAX_CLIPBOARD_SIZE {
+          bail!(
+            "clipboard content exceeds maximum size of {} bytes",
+            MAX_CLIPBOARD_SIZE
+          );
+        }
+
+        content.extend_from_slice(&temp_buffer[..bytes_read]);
+      }
+
+      // Set environment variable safely
+      set_clipboard_state_env(!content.is_empty())?;
+
+      // Spawn the command with the content as stdin
+      cmd.stdin(Stdio::piped());
+
+      let mut child = cmd.spawn()?;
+
+      if let Some(stdin) = child.stdin.take() {
+        let mut stdin = stdin;
+        if let Err(e) = stdin.write_all(&content) {
+          bail!("failed to write to command stdin: {e}");
+        }
+      }
+
+      match child.wait() {
+        Ok(status) => {
+          if !status.success() {
+            log::warn!("watch command exited with status: {status}");
+          }
+        },
+        Err(e) => {
+          bail!("failed to wait for command: {e}");
+        },
+      }
+    },
+    Err(PasteError::ClipboardEmpty) => {
+      // Set environment variable safely
+      set_clipboard_state_env(false)?;
+
+      // Run command with /dev/null as stdin
+      cmd.stdin(Stdio::null());
+
+      match cmd.status() {
+        Ok(status) => {
+          if !status.success() {
+            log::warn!("watch command exited with status: {status}");
+          }
+        },
+        Err(e) => {
+          bail!("failed to run command: {e}");
+        },
+      }
+    },
+    Err(e) => {
+      bail!("clipboard error: {e}");
+    },
+  }
+
+  Ok(())
+}
+
+fn handle_regular_paste(
+  args: &WlPasteArgs,
+  clipboard: PasteClipboardType,
+  seat: PasteSeat,
+) -> Result<()> {
+  let mime_type = get_paste_mime_type(args.mime_type.as_deref());
+
+  match get_contents(clipboard, seat, mime_type) {
+    Ok((mut reader, _types)) => {
+      let mut out = io::stdout();
+      let mut buf = Vec::new();
+      let mut temp_buffer = [0; 8192];
+
+      loop {
+        let bytes_read = reader
+          .read(&mut temp_buffer)
+          .context("failed to read clipboard")?;
+
+        if bytes_read == 0 {
+          break;
+        }
+
+        if buf.len() + bytes_read > MAX_CLIPBOARD_SIZE {
+          bail!(
+            "clipboard content exceeds maximum size of {} bytes",
+            MAX_CLIPBOARD_SIZE
+          );
+        }
+
+        buf.extend_from_slice(&temp_buffer[..bytes_read]);
+      }
+
+      if buf.is_empty() && args.no_newline {
+        bail!("no content available and --no-newline specified");
+      }
+      if let Err(e) = out.write_all(&buf) {
+        bail!("failed to write to stdout: {e}");
+      }
+      if !args.no_newline && !buf.ends_with(b"\n") {
+        if let Err(e) = out.write_all(b"\n") {
+          bail!("failed to write newline to stdout: {e}");
+        }
+      }
+    },
+    Err(PasteError::NoSeats) => {
+      bail!("no seats available (is a Wayland compositor running?)");
+    },
+    Err(PasteError::ClipboardEmpty) => {
+      if args.no_newline {
+        bail!("clipboard empty and --no-newline specified");
+      }
+      // Otherwise, exit successfully with no output
+    },
+    Err(PasteError::NoMimeType) => {
+      bail!("clipboard does not contain requested MIME type");
+    },
+    Err(e) => {
+      bail!("clipboard error: {e}");
+    },
+  }
+
+  Ok(())
+}
+
+pub fn wl_paste_main() -> Result<()> {
+  let args = WlPasteArgs::parse();
+
+  let clipboard = if args.primary {
+    PasteClipboardType::Primary
+  } else {
+    PasteClipboardType::Regular
+  };
+  let seat = args
+    .seat
+    .as_deref()
+    .map_or(PasteSeat::Unspecified, PasteSeat::Specific);
+
+  // Handle list-types option
+  if args.list_types {
+    handle_list_types(clipboard, seat)?;
+    return Ok(());
+  }
+
+  // Handle watch mode
+  if args.watch.is_some() {
+    handle_watch_mode(&args, clipboard, seat)?;
+    return Ok(());
+  }
+
+  // Regular paste mode
+  handle_regular_paste(&args, clipboard, seat)?;
+
+  Ok(())
+}