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
317
318
319
320
321
322
323
324
325
326
327
328
329
330
//! Create master and slave virtual pseudo-terminals (PTYs)

use libc;

pub use libc::pid_t as SessionId;
pub use libc::winsize as Winsize;

use std::ffi::CStr;
use std::mem;
use std::os::unix::prelude::*;

use sys::termios::Termios;
use unistd::ForkResult;
use {Result, Error, fcntl};
use errno::Errno;

/// Representation of a master/slave pty pair
///
/// This is returned by `openpty`.  Note that this type does *not* implement `Drop`, so the user
/// must manually close the file descriptors.
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub struct OpenptyResult {
    /// The master port in a virtual pty pair
    pub master: RawFd,
    /// The slave port in a virtual pty pair
    pub slave: RawFd,
}

/// Representation of a master with a forked pty
///
/// This is returned by `forkpty`. Note that this type does *not* implement `Drop`, so the user
/// must manually close the file descriptors.
#[derive(Clone, Copy, Debug)]
pub struct ForkptyResult {
    /// The master port in a virtual pty pair
    pub master: RawFd,
    /// Metadata about forked process
    pub fork_result: ForkResult,
}


/// Representation of the Master device in a master/slave pty pair
///
/// While this datatype is a thin wrapper around `RawFd`, it enforces that the available PTY
/// functions are given the correct file descriptor. Additionally this type implements `Drop`,
/// so that when it's consumed or goes out of scope, it's automatically cleaned-up.
#[derive(Clone, Debug, Eq, Hash, PartialEq)]
pub struct PtyMaster(RawFd);

impl AsRawFd for PtyMaster {
    fn as_raw_fd(&self) -> RawFd {
        self.0
    }
}

impl IntoRawFd for PtyMaster {
    fn into_raw_fd(self) -> RawFd {
        let fd = self.0;
        mem::forget(self);
        fd
    }
}

impl Drop for PtyMaster {
    fn drop(&mut self) {
        // On drop, we ignore errors like EINTR and EIO because there's no clear
        // way to handle them, we can't return anything, and (on FreeBSD at
        // least) the file descriptor is deallocated in these cases.  However,
        // we must panic on EBADF, because it is always an error to close an
        // invalid file descriptor.  That frequently indicates a double-close
        // condition, which can cause confusing errors for future I/O
        // operations.
        let e = ::unistd::close(self.0);
        if e == Err(Error::Sys(Errno::EBADF)) {
            panic!("Closing an invalid file descriptor!");
        };
    }
}

/// Grant access to a slave pseudoterminal (see
/// [`grantpt(3)`](http://pubs.opengroup.org/onlinepubs/9699919799/functions/grantpt.html))
///
/// `grantpt()` changes the mode and owner of the slave pseudoterminal device corresponding to the
/// master pseudoterminal referred to by `fd`. This is a necessary step towards opening the slave.
#[inline]
pub fn grantpt(fd: &PtyMaster) -> Result<()> {
    if unsafe { libc::grantpt(fd.as_raw_fd()) } < 0 {
        return Err(Error::last());
    }

    Ok(())
}

/// Open a pseudoterminal device (see
/// [`posix_openpt(3)`](http://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_openpt.html))
///
/// `posix_openpt()` returns a file descriptor to an existing unused pseuterminal master device.
///
/// # Examples
///
/// A common use case with this function is to open both a master and slave PTY pair. This can be
/// done as follows:
///
/// ```
/// use std::path::Path;
/// use nix::fcntl::{OFlag, open};
/// use nix::pty::{grantpt, posix_openpt, ptsname, unlockpt};
/// use nix::sys::stat::Mode;
///
/// # #[allow(dead_code)]
/// # fn run() -> nix::Result<()> {
/// // Open a new PTY master
/// let master_fd = posix_openpt(OFlag::O_RDWR)?;
///
/// // Allow a slave to be generated for it
/// grantpt(&master_fd)?;
/// unlockpt(&master_fd)?;
///
/// // Get the name of the slave
/// let slave_name = unsafe { ptsname(&master_fd) }?;
///
/// // Try to open the slave
/// let _slave_fd = open(Path::new(&slave_name), OFlag::O_RDWR, Mode::empty())?;
/// # Ok(())
/// # }
/// ```
#[inline]
pub fn posix_openpt(flags: fcntl::OFlag) -> Result<PtyMaster> {
    let fd = unsafe {
        libc::posix_openpt(flags.bits())
    };

    if fd < 0 {
        return Err(Error::last());
    }

    Ok(PtyMaster(fd))
}

/// Get the name of the slave pseudoterminal (see
/// [`ptsname(3)`](http://man7.org/linux/man-pages/man3/ptsname.3.html))
///
/// `ptsname()` returns the name of the slave pseudoterminal device corresponding to the master
/// referred to by `fd`.
///
/// This value is useful for opening the slave pty once the master has already been opened with
/// `posix_openpt()`.
///
/// # Safety
///
/// `ptsname()` mutates global variables and is *not* threadsafe.
/// Mutating global variables is always considered `unsafe` by Rust and this
/// function is marked as `unsafe` to reflect that.
///
/// For a threadsafe and non-`unsafe` alternative on Linux, see `ptsname_r()`.
#[inline]
pub unsafe fn ptsname(fd: &PtyMaster) -> Result<String> {
    let name_ptr = libc::ptsname(fd.as_raw_fd());
    if name_ptr.is_null() {
        return Err(Error::last());
    }

    let name = CStr::from_ptr(name_ptr);
    Ok(name.to_string_lossy().into_owned())
}

/// Get the name of the slave pseudoterminal (see
/// [`ptsname(3)`](http://man7.org/linux/man-pages/man3/ptsname.3.html))
///
/// `ptsname_r()` returns the name of the slave pseudoterminal device corresponding to the master
/// referred to by `fd`. This is the threadsafe version of `ptsname()`, but it is not part of the
/// POSIX standard and is instead a Linux-specific extension.
///
/// This value is useful for opening the slave ptty once the master has already been opened with
/// `posix_openpt()`.
#[cfg(any(target_os = "android", target_os = "linux"))]
#[inline]
pub fn ptsname_r(fd: &PtyMaster) -> Result<String> {
    let mut name_buf = vec![0u8; 64];
    let name_buf_ptr = name_buf.as_mut_ptr() as *mut libc::c_char;
    if unsafe { libc::ptsname_r(fd.as_raw_fd(), name_buf_ptr, name_buf.capacity()) } != 0 {
        return Err(Error::last());
    }

    // Find the first null-character terminating this string. This is guaranteed to succeed if the
    // return value of `libc::ptsname_r` is 0.
    let null_index = name_buf.iter().position(|c| *c == b'\0').unwrap();
    name_buf.truncate(null_index);

    let name = String::from_utf8(name_buf)?;
    Ok(name)
}

/// Unlock a pseudoterminal master/slave pseudoterminal pair (see
/// [`unlockpt(3)`](http://pubs.opengroup.org/onlinepubs/9699919799/functions/unlockpt.html))
///
/// `unlockpt()` unlocks the slave pseudoterminal device corresponding to the master pseudoterminal
/// referred to by `fd`. This must be called before trying to open the slave side of a
/// pseuoterminal.
#[inline]
pub fn unlockpt(fd: &PtyMaster) -> Result<()> {
    if unsafe { libc::unlockpt(fd.as_raw_fd()) } < 0 {
        return Err(Error::last());
    }

    Ok(())
}


/// Create a new pseudoterminal, returning the slave and master file descriptors
/// in `OpenptyResult`
/// (see [`openpty`](http://man7.org/linux/man-pages/man3/openpty.3.html)).
///
/// If `winsize` is not `None`, the window size of the slave will be set to
/// the values in `winsize`. If `termios` is not `None`, the pseudoterminal's
/// terminal settings of the slave will be set to the values in `termios`.
#[inline]
pub fn openpty<'a, 'b, T: Into<Option<&'a Winsize>>, U: Into<Option<&'b Termios>>>(winsize: T, termios: U) -> Result<OpenptyResult> {
    use std::ptr;

    let mut slave = mem::MaybeUninit::<libc::c_int>::uninit();
    let mut master = mem::MaybeUninit::<libc::c_int>::uninit();
    let ret = {
        match (termios.into(), winsize.into()) {
            (Some(termios), Some(winsize)) => {
                let inner_termios = termios.get_libc_termios();
                unsafe {
                    libc::openpty(
                        master.as_mut_ptr(),
                        slave.as_mut_ptr(),
                        ptr::null_mut(),
                        &*inner_termios as *const libc::termios as *mut _,
                        winsize as *const Winsize as *mut _,
                    )
                }
            }
            (None, Some(winsize)) => {
                unsafe {
                    libc::openpty(
                        master.as_mut_ptr(),
                        slave.as_mut_ptr(),
                        ptr::null_mut(),
                        ptr::null_mut(),
                        winsize as *const Winsize as *mut _,
                    )
                }
            }
            (Some(termios), None) => {
                let inner_termios = termios.get_libc_termios();
                unsafe {
                    libc::openpty(
                        master.as_mut_ptr(),
                        slave.as_mut_ptr(),
                        ptr::null_mut(),
                        &*inner_termios as *const libc::termios as *mut _,
                        ptr::null_mut(),
                    )
                }
            }
            (None, None) => {
                unsafe {
                    libc::openpty(
                        master.as_mut_ptr(),
                        slave.as_mut_ptr(),
                        ptr::null_mut(),
                        ptr::null_mut(),
                        ptr::null_mut(),
                    )
                }
            }
        }
    };

    Errno::result(ret)?;

    unsafe {
        Ok(OpenptyResult {
            master: master.assume_init(),
            slave: slave.assume_init(),
        })
    }
}

/// Create a new pseudoterminal, returning the master file descriptor and forked pid.
/// in `ForkptyResult`
/// (see [`forkpty`](http://man7.org/linux/man-pages/man3/forkpty.3.html)).
///
/// If `winsize` is not `None`, the window size of the slave will be set to
/// the values in `winsize`. If `termios` is not `None`, the pseudoterminal's
/// terminal settings of the slave will be set to the values in `termios`.
pub fn forkpty<'a, 'b, T: Into<Option<&'a Winsize>>, U: Into<Option<&'b Termios>>>(
    winsize: T,
    termios: U,
) -> Result<ForkptyResult> {
    use std::ptr;
    use unistd::Pid;
    use unistd::ForkResult::*;

    let mut master = mem::MaybeUninit::<libc::c_int>::uninit();

    let term = match termios.into() {
        Some(termios) => {
            let inner_termios = termios.get_libc_termios();
            &*inner_termios as *const libc::termios as *mut _
        },
        None => ptr::null_mut(),
    };

    let win = winsize
        .into()
        .map(|ws| ws as *const Winsize as *mut _)
        .unwrap_or(ptr::null_mut());

    let res = unsafe {
        libc::forkpty(master.as_mut_ptr(), ptr::null_mut(), term, win)
    };

    let fork_result = Errno::result(res).map(|res| match res {
        0 => Child,
        res => Parent { child: Pid::from_raw(res) },
    })?;

    unsafe {
        Ok(ForkptyResult {
            master: master.assume_init(),
            fork_result,
        })
    }
}