1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

use anyhow::{Context as _, Error};
use fidl::endpoints::ServerEnd;
use fidl_fuchsia_hardware_pty::{DeviceMarker, DeviceProxy, WindowSize};
use fuchsia_component::client::connect_to_protocol;
use fuchsia_trace as ftrace;
use std::ffi::CStr;
use std::fs::File;
use std::os::fd::OwnedFd;
use zx::{self as zx, HandleBased as _, ProcessInfo, ProcessInfoFlags};

/// An object used for interacting with the shell.
#[derive(Clone)]
pub struct ServerPty {
    // The server side pty connection.
    proxy: DeviceProxy,
}

pub struct ShellProcess {
    pub pty: ServerPty,

    // The running shell process. This process will be closed when the
    // Pty goes out of scope so there is no need to explicitly close it.
    process: zx::Process,
}

impl ServerPty {
    /// Creates a new instance of the Pty which must later be spawned.
    pub fn new() -> Result<Self, Error> {
        ftrace::duration!(c"pty", c"Pty:new");
        let proxy =
            connect_to_protocol::<DeviceMarker>().context("could not connect to pty service")?;
        Ok(Self { proxy })
    }

    /// Spawns the Pty.
    ///
    /// If no command is provided the default /boot/bin/sh will be used.
    ///
    /// After calling this method the user must call resize to give the process a
    /// valid window size before it will respond.
    ///
    /// The launched process will close when the Pty is dropped so you do not need to
    /// explicitly close it.
    pub async fn spawn(
        self,
        command: Option<&CStr>,
        environ: Option<&[&CStr]>,
    ) -> Result<ShellProcess, Error> {
        let command = command.unwrap_or(&c"/boot/bin/sh");
        self.spawn_with_argv(command, &[command], environ).await
    }

    pub async fn spawn_with_argv(
        self,
        command: &CStr,
        argv: &[&CStr],
        environ: Option<&[&CStr]>,
    ) -> Result<ShellProcess, Error> {
        ftrace::duration!(c"pty", c"Pty:spawn");
        let client_pty = self.open_client_pty().await.context("unable to create client_pty")?;
        let process = match fdio::spawn_etc(
            &zx::Job::from_handle(zx::Handle::invalid()),
            fdio::SpawnOptions::CLONE_ALL - fdio::SpawnOptions::CLONE_STDIO,
            command,
            argv,
            environ,
            &mut [fdio::SpawnAction::transfer_fd(client_pty, fdio::SpawnAction::USE_FOR_STDIO)],
        ) {
            Ok(process) => process,
            Err((status, reason)) => {
                return Err(status).context(format!("failed to spawn shell: {}", reason));
            }
        };

        Ok(ShellProcess { pty: self, process })
    }

    /// Attempts to clone the server side of the file descriptor.
    pub fn try_clone_fd(&self) -> Result<File, Error> {
        use std::os::fd::AsRawFd as _;

        let Self { proxy } = self;
        let (client_end, server_end) = fidl::endpoints::create_endpoints();
        let () = proxy.clone2(server_end)?;
        let file: File = fdio::create_fd(client_end.into())
            .context("failed to create FD from server PTY")?
            .into();
        let fd = file.as_raw_fd();
        let previous = {
            let res = unsafe { libc::fcntl(fd, libc::F_GETFL) };
            if res == -1 {
                Err(std::io::Error::last_os_error()).context("failed to get file status flags")
            } else {
                Ok(res)
            }
        }?;
        let new = previous | libc::O_NONBLOCK;
        if new != previous {
            let res = unsafe { libc::fcntl(fd, libc::F_SETFL, new) };
            let () = if res == -1 {
                Err(std::io::Error::last_os_error()).context("failed to set file status flags")
            } else {
                Ok(())
            }?;
        }
        Ok(file)
    }

    /// Sends a message to the shell that the window has been resized.
    pub async fn resize(&self, window_size: WindowSize) -> Result<(), Error> {
        ftrace::duration!(c"pty", c"Pty:resize");
        let Self { proxy } = self;
        let () = proxy
            .set_window_size(&window_size)
            .await
            .map(zx::Status::ok)
            .context("unable to call resize window")?
            .context("failed to resize window")?;
        Ok(())
    }

    /// Creates a File which is suitable to use as the client side of the Pty.
    async fn open_client_pty(&self) -> Result<OwnedFd, Error> {
        ftrace::duration!(c"pty", c"Pty:open_client_pty");
        let (client_end, server_end) = fidl::endpoints::create_endpoints();
        let () = self.open_client(server_end).await.context("failed to open client")?;
        let fd =
            fdio::create_fd(client_end.into()).context("failed to create FD from client PTY")?;
        Ok(fd)
    }

    /// Open a client Pty device. `server_end` should be a handle
    /// to one endpoint of a channel that (on success) will become an open
    /// connection to the newly created device.
    pub async fn open_client(&self, server_end: ServerEnd<DeviceMarker>) -> Result<(), Error> {
        let Self { proxy } = self;
        ftrace::duration!(c"pty", c"Pty:open_client");

        let () = proxy
            .open_client(0, server_end)
            .await
            .map(zx::Status::ok)
            .context("failed to interact with PTY device")?
            .context("failed to attach PTY to channel")?;

        Ok(())
    }
}

impl ShellProcess {
    /// Returns the shell process info, if available.
    pub fn process_info(&self) -> Result<ProcessInfo, Error> {
        let Self { pty: _, process } = self;
        process.info().context("failed to get process info")
    }

    /// Checks that the shell process has been started and has not exited.
    pub fn is_running(&self) -> bool {
        self.process_info()
            .map(|info| {
                let flags = ProcessInfoFlags::from_bits(info.flags).unwrap();
                flags.contains(zx::ProcessInfoFlags::STARTED)
                    && !flags.contains(ProcessInfoFlags::EXITED)
            })
            .unwrap_or_default()
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use cstr::cstr;
    use fuchsia_async as fasync;
    use futures::io::AsyncWriteExt as _;
    use std::os::unix::io::AsRawFd as _;
    use zx::AsHandleRef as _;

    #[fasync::run_singlethreaded(test)]
    async fn can_create_pty() -> Result<(), Error> {
        let _ = ServerPty::new()?;
        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn can_open_client_pty() -> Result<(), Error> {
        let server_pty = ServerPty::new()?;
        let client_pty = server_pty.open_client_pty().await?;
        assert!(client_pty.as_raw_fd() > 0);

        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn can_spawn_shell_process() -> Result<(), Error> {
        let server_pty = ServerPty::new()?;
        let cmd = cstr!("/pkg/bin/sh");
        let process = server_pty.spawn_with_argv(&cmd, &[cmd], None).await?;

        let mut started = false;
        if let Ok(info) = process.process_info() {
            started = ProcessInfoFlags::from_bits(info.flags)
                .unwrap()
                .contains(zx::ProcessInfoFlags::STARTED);
        }

        assert_eq!(started, true);

        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn shell_process_is_spawned() -> Result<(), Error> {
        let process = spawn_pty().await?;

        let info = process.process_info().unwrap();
        assert!(ProcessInfoFlags::from_bits(info.flags)
            .unwrap()
            .contains(zx::ProcessInfoFlags::STARTED));

        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn spawned_shell_process_is_running() -> Result<(), Error> {
        let process = spawn_pty().await?;

        assert!(process.is_running());
        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn exited_shell_process_is_not_running() -> Result<(), Error> {
        let window_size = WindowSize { width: 300 as u32, height: 300 as u32 };
        let pty = ServerPty::new().unwrap();

        // While argv[0] is usually the executable path, this particular program expects it to be
        // an integer which is then parsed and returned as the status code.
        let process = pty
            .spawn_with_argv(&cstr!("/pkg/bin/exit_with_code_util"), &[cstr!("42")], None)
            .await?;
        let () = process.pty.resize(window_size).await?;

        // Since these tests don't seem to timeout automatically, we must
        // specify a deadline and cannot simply rely on fasync::OnSignals.
        process
            .process
            .wait_handle(
                zx::Signals::PROCESS_TERMINATED,
                zx::MonotonicInstant::after(zx::MonotonicDuration::from_seconds(60)),
            )
            .expect("shell process did not exit in time");

        assert!(!process.is_running());
        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn can_write_to_shell() -> Result<(), Error> {
        let process = spawn_pty().await?;
        // EventedFd::new() is unsafe because it can't guarantee the lifetime of
        // the file descriptor passed to it exceeds the lifetime of the EventedFd.
        // Since we're cloning the file when passing it in, the EventedFd
        // effectively owns that file descriptor and thus controls it's lifetime.
        let mut evented_fd = unsafe { fasync::net::EventedFd::new(process.pty.try_clone_fd()?)? };

        evented_fd.write_all("a".as_bytes()).await?;

        Ok(())
    }

    #[ignore] // TODO(63868): until we figure out why this test is flaking.
    #[fasync::run_singlethreaded(test)]
    async fn shell_process_is_not_running_after_writing_exit() -> Result<(), Error> {
        let process = spawn_pty().await?;
        // EventedFd::new() is unsafe because it can't guarantee the lifetime of
        // the file descriptor passed to it exceeds the lifetime of the EventedFd.
        // Since we're cloning the file when passing it in, the EventedFd
        // effectively owns that file descriptor and thus controls it's lifetime.
        let mut evented_fd = unsafe { fasync::net::EventedFd::new(process.pty.try_clone_fd()?)? };

        evented_fd.write_all("exit\n".as_bytes()).await?;

        // Since these tests don't seem to timeout automatically, we must
        // specify a deadline and cannot simply rely on fasync::OnSignals.
        process
            .process
            .wait_handle(
                zx::Signals::PROCESS_TERMINATED,
                zx::MonotonicInstant::after(zx::MonotonicDuration::from_seconds(60)),
            )
            .expect("shell process did not exit in time");

        assert!(!process.is_running());

        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn can_resize_window() -> Result<(), Error> {
        let process = spawn_pty().await?;
        let () = process.pty.resize(WindowSize { width: 400, height: 400 }).await?;
        Ok(())
    }

    async fn spawn_pty() -> Result<ShellProcess, Error> {
        let window_size = WindowSize { width: 300 as u32, height: 300 as u32 };
        let pty = ServerPty::new()?;
        let process = pty.spawn(Some(&c"/pkg/bin/sh"), None).await.context("failed to spawn")?;
        let () = process.pty.resize(window_size).await?;
        Ok(process)
    }
}