Portty

Portty routes XDG Desktop Portal D-Bus requests into plain files and Unix sockets. Anything that can read and write files can respond to portal requests — a terminal, a shell script, a keybinding daemon, or echo.

Implemented Portals

Portal	Operations	Description
FileChooser	open-file, save-file, save-files	File open/save dialogs
Screenshot	screenshot, pick-color	Screen capture and color picking

Architecture

graph TD
    App[Application] -->|D-Bus| Daemon[porttyd]

    Daemon --> Socket[daemon.sock<br>Unix socket]
    Daemon --> FIFO[daemon.ctl<br>FIFO]
    Daemon --> Session[Session<br>file-based state]

    Session -->|exec| Process[Spawned process]
    Process -->|exit triggers submit| Session

    Session --- Files[/"submission (file)<br>options.json (file)<br>portal (file)"/]

    CLI[portty CLI] -->|control commands| Socket
    CLI -->|read/write| Files
    Script[Shell scripts<br>echo, cat, ...] -->|read/write| Files
    Script -->|"echo submit >"| FIFO
    Shims["Shims (sel, submit, ...)<br>= portty CLI wrappers"] --> CLI

Workspace

Crate	Binary	Description
crates/lib (libportty)	—	Shared library: protocol, codec, client, paths, files, portal validation
crates/daemon (porttyd)	porttyd	D-Bus service, session management, daemon socket + FIFO
crates/cli (portty)	portty	CLI for interacting with sessions and the daemon

Data Flow

1. An application requests a portal action via D-Bus (e.g. open file dialog)
2. The daemon checks for a queued submission — if one exists, it auto-applies and returns immediately
3. Otherwise, the daemon creates a session directory with file-based state (options.json, submission, portal)
4. The configured exec command is run (typically a terminal emulator, but can be any program — even submit for instant auto-confirm). If the process exits, the session submits automatically
5. The session's submission file can be edited by anything — the portty CLI, shell shims on $PATH, raw file I/O, or commands piped into the FIFO
6. On submit/cancel, the daemon reads the submission file, validates it against portal constraints, and returns results via D-Bus

Session Directory

/tmp/portty/<uid>/
├── daemon.sock                # Unix socket (CLI <-> daemon, bidirectional)
├── daemon.ctl                 # FIFO (fire-and-forget commands)
├── pending/submission         # Entries queued before any session exists
├── submissions/<ts>-<portal>/ # Queued submissions (auto-applied on next dialog)
│   └── submission
└── <session-id>/
    ├── portal                 # "<portal>\n<operation>" (e.g. "file-chooser\nopen-file")
    ├── options.json           # Session options (from D-Bus request)
    ├── submission             # Current entries, one per line
    └── bin/                   # Shell shims prepended to $PATH
        ├── sel                # -> portty edit "$@"
        ├── desel              # -> portty edit --remove "$@"
        ├── reset              # -> portty edit --reset
        ├── submit             # -> portty submit
        ├── cancel             # -> portty cancel
        ├── info               # -> portty info
        └── <custom>           # From config [portal.bin] section

All data operations (editing submissions) are file-based. The daemon socket handles control commands only (submit, cancel, verify, reset, list).

Interaction

There are multiple ways to interact with a session — they all do the same thing (edit files, send control commands):

portty CLI / shims

The shims in bin/ are one-line wrappers around portty. They're the same thing.

# These are equivalent:
sel file1.txt file2.txt        # shim
portty edit file1.txt file2.txt # CLI directly

# Edit submission
portty edit file1.txt file2.txt
portty edit --stdin              # read from stdin
portty edit --remove file1.txt   # remove entries
portty edit --clear              # clear all
portty edit --reset              # reset to initial state
portty edit                      # no args = print current entries

# Control
portty submit                    # confirm and complete the dialog
portty cancel                    # cancel the operation
portty verify                    # validate against portal constraints
portty info                      # show options.json + submission

# Management (context-independent)
portty list                      # list active sessions
portty queue                     # show pending + queued submissions

# Target a specific session
portty --session <id> submit

The CLI auto-detects context via PORTTY_SESSION env var — inside a session terminal it operates on the session directory, outside it operates on pending entries.

Raw file I/O

Since state is just files, you can skip the CLI entirely:

# Read options
cat /tmp/portty/$(id -u)/<session-id>/options.json

# Write submission directly
echo "/path/to/file.txt" >> /tmp/portty/$(id -u)/<session-id>/submission

# Clear submission
> /tmp/portty/$(id -u)/<session-id>/submission

FIFO

Fire-and-forget commands — useful for scripting and keybindings:

echo "submit" > /tmp/portty/$(id -u)/daemon.ctl
echo "cancel" > /tmp/portty/$(id -u)/daemon.ctl
echo "submit my-session-id" > /tmp/portty/$(id -u)/daemon.ctl

Unix socket

For bidirectional communication (when you need the response):

echo "list" | socat - UNIX-CONNECT:/tmp/portty/$(id -u)/daemon.sock

Submission Queue

Pre-queue entries before a dialog opens. When the next dialog arrives, the queued submission is auto-applied without running exec:

portty edit file1.txt file2.txt
portty submit
portty queue  # view the queue

Daemon Control Protocol

Plain text, newline-terminated. Shared by the socket and FIFO.

Request (single line)

submit [session_id]
cancel [session_id]
verify [session_id]
reset [session_id]
list

When session_id is omitted, the earliest active session is targeted.

Response (socket only — FIFO discards responses)

ok
error: <message>
<id>\t<portal>\t<operation>\t<created>\t<dir>\t<title>\n
...
ok

Session listing emits one tab-separated line per session, terminated by ok.

Configuration

~/.config/portty/config.toml — see misc/config.toml.example for a full annotated example.

Config resolution priority: operation-specific > portal-specific > root default.

exec = "foot"             # root default (auto-detected if not set)

[file-chooser]
exec = "foot"             # portal default

[file-chooser.save-file]
exec = "submit"           # operation override: auto-confirm saves

[file-chooser.bin]
pick = "fzf --multi | sel --stdin"  # custom shim on $PATH

Set exec = "" for headless mode (no process spawned, interact via CLI only).

Session Environment

Variable	Description
PORTTY_SESSION	Session ID
PORTTY_DIR	Session directory path
PORTTY_PORTAL	Portal name (e.g. file-chooser)
PORTTY_OPERATION	Operation name (e.g. open-file)

The session bin/ directory is prepended to $PATH.

Adding a New Portal

1. Define validation logic in libportty

Create crates/lib/src/portal/<portal>.rs:

use serde::{Deserialize, Serialize};

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SessionOptions {
    // Fields from the D-Bus request that the session/CLI needs
}

/// Validate and transform submission entries.
/// Called at submit time — check constraints and produce final output.
pub fn validate(
    operation: &str,
    entries: &[String],
    options: &SessionOptions,
) -> Result<Vec<String>, String> {
    // Validate entries against options, return transformed entries
    Ok(entries.to_vec())
}

/// Smart add behavior (single-select replace vs multi-select append).
pub fn add_entries(
    sub_path: &std::path::Path,
    entries: &[String],
    options: &SessionOptions,
) -> std::io::Result<super::AddResult> {
    crate::files::append_lines(sub_path, entries)?;
    Ok(super::AddResult::Appended(entries.len()))
}

Register in crates/lib/src/portal/mod.rs:

#[cfg(feature = "portal-my-portal")]
pub mod my_portal;

Add the feature to crates/lib/Cargo.toml:

[features]
portal-my-portal = ["portal"]

Wire it into SessionContext::add_entries() and validate() in crates/lib/src/portal/mod.rs.

2. Define D-Bus types in porttyd

Create crates/daemon/src/dbus/<portal>.rs implementing the org.freedesktop.impl.portal.* interface using zbus. See dbus/file_chooser.rs or dbus/screenshot.rs as examples.

The key pattern: define a Handler trait that the portal implementation calls, and a D-Bus proxy struct that implements the zbus interface and delegates to the handler.

3. Implement the portal handler

Create crates/daemon/src/portal/<portal>.rs:

pub struct TtyMyPortal {
    config: Arc<Config>,
    state: Arc<RwLock<DaemonState>>,
}

impl MyPortalHandler for TtyMyPortal {
    async fn my_operation(&self, ...) -> Result<MyResult, MyError> {
        let session_options = SessionOptions { /* ... */ };
        let options_json = serde_json::to_value(&session_options)?;

        let entries = super::run_session(
            "my-portal",        // portal name
            "my-operation",     // operation name
            &options_json,
            &initial_entries,
            title.as_deref(),
            &self.config,
            &self.state,
        ).await?;

        // Transform entries into D-Bus result
        Ok(MyResult::new(entries))
    }
}

run_session handles the entire lifecycle: queued submission check -> session creation -> exec spawn -> wait -> unregister -> validate.

4. Register in the server

In crates/daemon/src/server.rs, add to register_portals():

let my_portal = TtyMyPortal::new(Arc::clone(&self.config), Arc::clone(&self.state));
let builder = builder.serve_at(OBJECT_PATH, MyPortalProxy::from(my_portal))?;

5. Update the portal file

In misc/tty.portal, add the interface:

Interfaces=...;org.freedesktop.impl.portal.MyPortal

Building

cargo build --release

Requires nightly Rust (uses linux_pidfd and unix_mkfifo features).

Installation

# Install binaries
install -Dm755 target/release/porttyd /usr/lib/portty/porttyd
install -Dm755 target/release/portty /usr/bin/portty

# Install portal file
install -Dm644 misc/tty.portal /usr/share/xdg-desktop-portal/portals/tty.portal

# Install systemd service (optional)
install -Dm644 misc/portty.service /usr/lib/systemd/user/portty.service

License

MIT