path: root/src/lib.rs

//! Rust friendly bindings to the various *nix system functions.
//!
//! Modules are structured according to the C header file that they would be
//! defined in.
#![crate_name = "nix"]
#![cfg(unix)]
#![allow(non_camel_case_types)]
// latest bitflags triggers a rustc bug with cross-crate macro expansions causing dead_code
// warnings even though the macro expands into something with allow(dead_code)
#![allow(dead_code)]
#![cfg_attr(test, deny(warnings))]
#![recursion_limit = "500"]

#[macro_use]
extern crate bitflags;

#[macro_use]
extern crate cfg_if;
extern crate void;

#[cfg(test)]
extern crate nix_test as nixtest;

#[macro_use] mod macros;

// In rust 1.8+ this should be `pub extern crate libc` but prior
// to https://github.com/rust-lang/rust/issues/26775 being resolved
// it is necessary to get a little creative.
pub mod libc {
    extern crate libc;
    pub use self::libc::*;
}

pub use libc::{c_int, c_void};
pub use errno::Errno;

pub mod errno;
pub mod features;
pub mod fcntl;

#[cfg(any(target_os = "linux", target_os = "android"))]
pub mod mount;

#[cfg(target_os = "linux")]
pub mod mqueue;

pub mod pty;

#[cfg(any(target_os = "linux", target_os = "macos"))]
pub mod poll;

pub mod net;

#[cfg(any(target_os = "linux", target_os = "android"))]
pub mod sched;

pub mod sys;

// This can be implemented for other platforms as soon as libc
// provides bindings for them.
#[cfg(all(target_os = "linux",
          any(target_arch = "x86", target_arch = "x86_64")))]
pub mod ucontext;

pub mod unistd;

/*
 *
 * ===== Result / Error =====
 *
 */

use libc::c_char;
use std::{ptr, result};
use std::ffi::{CStr, OsStr};
use std::path::{Path, PathBuf};
use std::os::unix::ffi::OsStrExt;
use std::fmt;
use std::error;
use libc::PATH_MAX;

/// Nix Result Type
pub type Result<T> = result::Result<T, Error>;

/// Nix Error Type
///
/// The nix error type provides a common way of dealing with
/// various system system/libc calls that might fail.  Each
/// error has a corresponding errno (usually the one from the
/// underlying OS) to which it can be mapped in addition to
/// implementing other common traits.
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum Error {
    Sys(errno::Errno),
    InvalidPath,
    /// The operation involved a conversion to Rust's native String type, which failed because the
    /// string did not contain all valid UTF-8.
    InvalidUtf8,
    /// The operation is not supported by Nix, in this instance either use the libc bindings or 
    /// consult the module documentation to see if there is a more appropriate interface available.
    UnsupportedOperation,
}

impl Error {

    /// Create a nix Error from a given errno
    pub fn from_errno(errno: errno::Errno) -> Error {
        Error::Sys(errno)
    }

    /// Get the current errno and convert it to a nix Error
    pub fn last() -> Error {
        Error::Sys(errno::Errno::last())
    }

    /// Create a new invalid argument error (`EINVAL`)
    pub fn invalid_argument() -> Error {
        Error::Sys(errno::EINVAL)
    }

}

impl From<errno::Errno> for Error {
    fn from(errno: errno::Errno) -> Error { Error::from_errno(errno) }
}

impl From<std::string::FromUtf8Error> for Error {
    fn from(_: std::string::FromUtf8Error) -> Error { Error::InvalidUtf8 }
}

impl error::Error for Error {
    fn description(&self) -> &str {
        match self {
            &Error::InvalidPath => "Invalid path",
            &Error::InvalidUtf8 => "Invalid UTF-8 string",
            &Error::UnsupportedOperation => "Unsupported Operation",
            &Error::Sys(ref errno) => errno.desc(),
        }
    }
}

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            &Error::InvalidPath => write!(f, "Invalid path"),
            &Error::InvalidUtf8 => write!(f, "Invalid UTF-8 string"),
            &Error::UnsupportedOperation => write!(f, "Unsupported Operation"),
            &Error::Sys(errno) => write!(f, "{:?}: {}", errno, errno.desc()),
        }
    }
}

pub trait NixPath {
    fn len(&self) -> usize;

    fn with_nix_path<T, F>(&self, f: F) -> Result<T>
        where F: FnOnce(&CStr) -> T;
}

impl NixPath for str {
    fn len(&self) -> usize {
        NixPath::len(OsStr::new(self))
    }

    fn with_nix_path<T, F>(&self, f: F) -> Result<T>
        where F: FnOnce(&CStr) -> T {
            OsStr::new(self).with_nix_path(f)
        }
}

impl NixPath for OsStr {
    fn len(&self) -> usize {
        self.as_bytes().len()
    }

    fn with_nix_path<T, F>(&self, f: F) -> Result<T>
        where F: FnOnce(&CStr) -> T {
            self.as_bytes().with_nix_path(f)
        }
}

impl NixPath for CStr {
    fn len(&self) -> usize {
        self.to_bytes().len()
    }

    fn with_nix_path<T, F>(&self, f: F) -> Result<T>
            where F: FnOnce(&CStr) -> T {
        // Equivalence with the [u8] impl.
        if self.len() >= PATH_MAX as usize {
            return Err(Error::InvalidPath);
        }

        Ok(f(self))
    }
}

impl NixPath for [u8] {
    fn len(&self) -> usize {
        self.len()
    }

    fn with_nix_path<T, F>(&self, f: F) -> Result<T>
            where F: FnOnce(&CStr) -> T {
        let mut buf = [0u8; PATH_MAX as usize];

        if self.len() >= PATH_MAX as usize {
            return Err(Error::InvalidPath);
        }

        match self.iter().position(|b| *b == 0) {
            Some(_) => Err(Error::InvalidPath),
            None => {
                unsafe {
                    // TODO: Replace with bytes::copy_memory. rust-lang/rust#24028
                    ptr::copy_nonoverlapping(self.as_ptr(), buf.as_mut_ptr(), self.len());
                    Ok(f(CStr::from_ptr(buf.as_ptr() as *const c_char)))
                }

            }
        }
    }
}

impl NixPath for Path {
    fn len(&self) -> usize {
        NixPath::len(self.as_os_str())
    }

    fn with_nix_path<T, F>(&self, f: F) -> Result<T> where F: FnOnce(&CStr) -> T {
        self.as_os_str().with_nix_path(f)
    }
}

impl NixPath for PathBuf {
    fn len(&self) -> usize {
        NixPath::len(self.as_os_str())
    }

    fn with_nix_path<T, F>(&self, f: F) -> Result<T> where F: FnOnce(&CStr) -> T {
        self.as_os_str().with_nix_path(f)
    }
}

/// Treats `None` as an empty string.
impl<'a, NP: ?Sized + NixPath>  NixPath for Option<&'a NP> {
    fn len(&self) -> usize {
        self.map_or(0, NixPath::len)
    }

    fn with_nix_path<T, F>(&self, f: F) -> Result<T> where F: FnOnce(&CStr) -> T {
        if let Some(nix_path) = *self {
            nix_path.with_nix_path(f)
        } else {
            unsafe { CStr::from_ptr("\0".as_ptr() as *const _).with_nix_path(f) }
        }
    }
}