test_unistd.rs

use nix::fcntl::{self, fcntl, FcntlArg, FdFlag, open, OFlag, readlink};
use nix::unistd::*;
use nix::unistd::ForkResult::*;
use nix::sys::signal::{SaFlags, SigAction, SigHandler, SigSet, Signal, sigaction};
use nix::sys::wait::*;
use nix::sys::stat::{self, Mode, SFlag};
use nix::errno::Errno;
use nix::Error;
use std::{env, iter};
use std::ffi::CString;
use std::fs::{self, DirBuilder, File};
use std::io::Write;
use std::os::unix::prelude::*;
use tempfile::{self, tempfile};
use libc::{self, _exit, off_t};

#[test]
#[cfg(not(any(target_os = "netbsd")))]
fn test_fork_and_waitpid() {
    let _m = ::FORK_MTX.lock().expect("Mutex got poisoned by another test");

    // Safe: Child only calls `_exit`, which is signal-safe
    match fork().expect("Error: Fork Failed") {
        Child => unsafe { _exit(0) },
        Parent { child } => {
            // assert that child was created and pid > 0
            let child_raw: ::libc::pid_t = child.into();
            assert!(child_raw > 0);
            let wait_status = waitpid(child, None);
            match wait_status {
                // assert that waitpid returned correct status and the pid is the one of the child
                Ok(WaitStatus::Exited(pid_t, _)) =>  assert_eq!(pid_t, child),

                // panic, must never happen
                s @ Ok(_) => panic!("Child exited {:?}, should never happen", s),

                // panic, waitpid should never fail
                Err(s) => panic!("Error: waitpid returned Err({:?}", s)
            }

        },
    }
}

#[test]
fn test_wait() {
    // Grab FORK_MTX so wait doesn't reap a different test's child process
    let _m = ::FORK_MTX.lock().expect("Mutex got poisoned by another test");

    // Safe: Child only calls `_exit`, which is signal-safe
    match fork().expect("Error: Fork Failed") {
        Child => unsafe { _exit(0) },
        Parent { child } => {
            let wait_status = wait();

            // just assert that (any) one child returns with WaitStatus::Exited
            assert_eq!(wait_status, Ok(WaitStatus::Exited(child, 0)));
        },
    }
}

#[test]
fn test_mkstemp() {
    let mut path = env::temp_dir();
    path.push("nix_tempfile.XXXXXX");

    let result = mkstemp(&path);
    match result {
        Ok((fd, path)) => {
            close(fd).unwrap();
            unlink(path.as_path()).unwrap();
        },
        Err(e) => panic!("mkstemp failed: {}", e)
    }
}

#[test]
fn test_mkstemp_directory() {
    // mkstemp should fail if a directory is given
    assert!(mkstemp(&env::temp_dir()).is_err());
}

#[test]
fn test_mkfifo() {
    let tempdir = tempfile::tempdir().unwrap();
    let mkfifo_fifo = tempdir.path().join("mkfifo_fifo");

    mkfifo(&mkfifo_fifo, Mode::S_IRUSR).unwrap();

    let stats = stat::stat(&mkfifo_fifo).unwrap();
    let typ = stat::SFlag::from_bits_truncate(stats.st_mode);
    assert!(typ == SFlag::S_IFIFO);
}

#[test]
fn test_mkfifo_directory() {
    // mkfifo should fail if a directory is given
    assert!(mkfifo(&env::temp_dir(), Mode::S_IRUSR).is_err());
}

#[test]
fn test_getpid() {
    let pid: ::libc::pid_t = getpid().into();
    let ppid: ::libc::pid_t = getppid().into();
    assert!(pid > 0);
    assert!(ppid > 0);
}

#[test]
fn test_getsid() {
    let none_sid: ::libc::pid_t = getsid(None).unwrap().into();
    let pid_sid: ::libc::pid_t = getsid(Some(getpid())).unwrap().into();
    assert!(none_sid > 0);
    assert_eq!(none_sid, pid_sid);
}

#[cfg(any(target_os = "linux", target_os = "android"))]
mod linux_android {
    use nix::unistd::gettid;

    #[test]
    fn test_gettid() {
        let tid: ::libc::pid_t = gettid().into();
        assert!(tid > 0);
    }
}

#[test]
// `getgroups()` and `setgroups()` do not behave as expected on Apple platforms
#[cfg(not(any(target_os = "ios", target_os = "macos")))]
fn test_setgroups() {
    // Skip this test when not run as root as `setgroups()` requires root.
    skip_if_not_root!("test_setgroups");

    let _m = ::GROUPS_MTX.lock().expect("Mutex got poisoned by another test");

    // Save the existing groups
    let old_groups = getgroups().unwrap();

    // Set some new made up groups
    let groups = [Gid::from_raw(123), Gid::from_raw(456)];
    setgroups(&groups).unwrap();

    let new_groups = getgroups().unwrap();
    assert_eq!(new_groups, groups);

    // Revert back to the old groups
    setgroups(&old_groups).unwrap();
}

#[test]
// `getgroups()` and `setgroups()` do not behave as expected on Apple platforms
#[cfg(not(any(target_os = "ios", target_os = "macos")))]
fn test_initgroups() {
    // Skip this test when not run as root as `initgroups()` and `setgroups()`
    // require root.
    skip_if_not_root!("test_initgroups");

    let _m = ::GROUPS_MTX.lock().expect("Mutex got poisoned by another test");

    // Save the existing groups
    let old_groups = getgroups().unwrap();

    // It doesn't matter if the root user is not called "root" or if a user
    // called "root" doesn't exist. We are just checking that the extra,
    // made-up group, `123`, is set.
    // FIXME: Test the other half of initgroups' functionality: whether the
    // groups that the user belongs to are also set.
    let user = CString::new("root").unwrap();
    let group = Gid::from_raw(123);
    let group_list = getgrouplist(&user, group).unwrap();
    assert!(group_list.contains(&group));

    initgroups(&user, group).unwrap();

    let new_groups = getgroups().unwrap();
    assert_eq!(new_groups, group_list);

    // Revert back to the old groups
    setgroups(&old_groups).unwrap();
}

macro_rules! execve_test_factory(
    ($test_name:ident, $syscall:ident, $exe: expr $(, $pathname:expr, $flags:expr)*) => (
    #[test]
    fn $test_name() {
        if "execveat" == stringify!($syscall) {
            // Though undocumented, Docker's default seccomp profile seems to
            // block this syscall.  https://github.com/nix-rust/nix/issues/1122
            skip_if_seccomp!($test_name);
        }

        let m = ::FORK_MTX.lock().expect("Mutex got poisoned by another test");
        // The `exec`d process will write to `writer`, and we'll read that
        // data from `reader`.
        let (reader, writer) = pipe().unwrap();

        // Safe: Child calls `exit`, `dup`, `close` and the provided `exec*` family function.
        // NOTE: Technically, this makes the macro unsafe to use because you could pass anything.
        //       The tests make sure not to do that, though.
        match fork().unwrap() {
            Child => {
                // Make `writer` be the stdout of the new process.
                dup2(writer, 1).unwrap();
                let r = $syscall(
                    $exe,
                    $(CString::new($pathname).unwrap().as_c_str(), )*
                    &[CString::new(b"".as_ref()).unwrap().as_c_str(),
                      CString::new(b"-c".as_ref()).unwrap().as_c_str(),
                      CString::new(b"echo nix!!! && echo foo=$foo && echo baz=$baz"
                                   .as_ref()).unwrap().as_c_str()],
                    &[CString::new(b"foo=bar".as_ref()).unwrap().as_c_str(),
                      CString::new(b"baz=quux".as_ref()).unwrap().as_c_str()]
                    $(, $flags)*);
                let _ = std::io::stderr()
                    .write_all(format!("{:?}", r).as_bytes());
                // Should only get here in event of error
                unsafe{ _exit(1) };
            },
            Parent { child } => {
                // Wait for the child to exit.
                let ws = waitpid(child, None);
                drop(m);
                assert_eq!(ws, Ok(WaitStatus::Exited(child, 0)));
                // Read 1024 bytes.
                let mut buf = [0u8; 1024];
                read(reader, &mut buf).unwrap();
                // It should contain the things we printed using `/bin/sh`.
                let string = String::from_utf8_lossy(&buf);
                assert!(string.contains("nix!!!"));
                assert!(string.contains("foo=bar"));
                assert!(string.contains("baz=quux"));
            }
        }
    }
    )
);

cfg_if!{
    if #[cfg(target_os = "android")] {
        execve_test_factory!(test_execve, execve, CString::new("/system/bin/sh").unwrap().as_c_str());
        execve_test_factory!(test_fexecve, fexecve, File::open("/system/bin/sh").unwrap().into_raw_fd());
    } else if #[cfg(any(target_os = "freebsd",
                        target_os = "linux"))] {
        execve_test_factory!(test_execve, execve, CString::new("/bin/sh").unwrap().as_c_str());
        execve_test_factory!(test_fexecve, fexecve, File::open("/bin/sh").unwrap().into_raw_fd());
    } else if #[cfg(any(target_os = "dragonfly",
                        target_os = "ios",
                        target_os = "macos",
                        target_os = "netbsd",
                        target_os = "openbsd"))] {
        execve_test_factory!(test_execve, execve, CString::new("/bin/sh").unwrap().as_c_str());
        // No fexecve() on DragonFly, ios, macos, NetBSD, OpenBSD.
        //
        // Note for NetBSD and OpenBSD: although rust-lang/libc includes it
        // (under unix/bsd/netbsdlike/) fexecve is not currently implemented on
        // NetBSD nor on OpenBSD.
    }
}

#[cfg(any(target_os = "haiku", target_os = "linux", target_os = "openbsd"))]
execve_test_factory!(test_execvpe, execvpe, &CString::new("sh").unwrap());

cfg_if!{
    if #[cfg(target_os = "android")] {
        use nix::fcntl::AtFlags;
        execve_test_factory!(test_execveat_empty, execveat, File::open("/system/bin/sh").unwrap().into_raw_fd(),
                             "", AtFlags::AT_EMPTY_PATH);
        execve_test_factory!(test_execveat_relative, execveat, File::open("/system/bin/").unwrap().into_raw_fd(),
                             "./sh", AtFlags::empty());
        execve_test_factory!(test_execveat_absolute, execveat, File::open("/").unwrap().into_raw_fd(),
                             "/system/bin/sh", AtFlags::empty());
    } else if #[cfg(all(target_os = "linux"), any(target_arch ="x86_64", target_arch ="x86"))] {
        use nix::fcntl::AtFlags;
        execve_test_factory!(test_execveat_empty, execveat, File::open("/bin/sh").unwrap().into_raw_fd(),
                             "", AtFlags::AT_EMPTY_PATH);
        execve_test_factory!(test_execveat_relative, execveat, File::open("/bin/").unwrap().into_raw_fd(),
                             "./sh", AtFlags::empty());
        execve_test_factory!(test_execveat_absolute, execveat, File::open("/").unwrap().into_raw_fd(),
                             "/bin/sh", AtFlags::empty());
    }
}

#[test]
fn test_fchdir() {
    // fchdir changes the process's cwd
    let _dr = ::DirRestore::new();

    let tmpdir = tempfile::tempdir().unwrap();
    let tmpdir_path = tmpdir.path().canonicalize().unwrap();
    let tmpdir_fd = File::open(&tmpdir_path).unwrap().into_raw_fd();

    assert!(fchdir(tmpdir_fd).is_ok());
    assert_eq!(getcwd().unwrap(), tmpdir_path);

    assert!(close(tmpdir_fd).is_ok());
}

#[test]
fn test_getcwd() {
    // chdir changes the process's cwd
    let _dr = ::DirRestore::new();

    let tmpdir = tempfile::tempdir().unwrap();
    let tmpdir_path = tmpdir.path().canonicalize().unwrap();
    assert!(chdir(&tmpdir_path).is_ok());
    assert_eq!(getcwd().unwrap(), tmpdir_path);

    // make path 500 chars longer so that buffer doubling in getcwd
    // kicks in.  Note: One path cannot be longer than 255 bytes
    // (NAME_MAX) whole path cannot be longer than PATH_MAX (usually
    // 4096 on linux, 1024 on macos)
    let mut inner_tmp_dir = tmpdir_path.to_path_buf();
    for _ in 0..5 {
        let newdir = iter::repeat("a").take(100).collect::<String>();
        inner_tmp_dir.push(newdir);
        assert!(mkdir(inner_tmp_dir.as_path(), Mode::S_IRWXU).is_ok());
    }
    assert!(chdir(inner_tmp_dir.as_path()).is_ok());
    assert_eq!(getcwd().unwrap(), inner_tmp_dir.as_path());
}

#[test]
fn test_chown() {
    // Testing for anything other than our own UID/GID is hard.
    let uid = Some(getuid());
    let gid = Some(getgid());

    let tempdir = tempfile::tempdir().unwrap();
    let path = tempdir.path().join("file");
    {
        File::create(&path).unwrap();
    }

    chown(&path, uid, gid).unwrap();
    chown(&path, uid, None).unwrap();
    chown(&path, None, gid).unwrap();

    fs::remove_file(&path).unwrap();
    chown(&path, uid, gid).unwrap_err();
}

#[test]
fn test_fchownat() {
    let _dr = ::DirRestore::new();
    // Testing for anything other than our own UID/GID is hard.
    let uid = Some(getuid());
    let gid = Some(getgid());

    let tempdir = tempfile::tempdir().unwrap();
    let path = tempdir.path().join("file");
    {
        File::create(&path).unwrap();
    }

    let dirfd = open(tempdir.path(), OFlag::empty(), Mode::empty()).unwrap();

    fchownat(Some(dirfd), "file", uid, gid, FchownatFlags::FollowSymlink).unwrap();

    chdir(tempdir.path()).unwrap();
    fchownat(None, "file", uid, gid, FchownatFlags::FollowSymlink).unwrap();

    fs::remove_file(&path).unwrap();
    fchownat(None, "file", uid, gid, FchownatFlags::FollowSymlink).unwrap_err();
}

#[test]
fn test_lseek() {
    const CONTENTS: &[u8] = b"abcdef123456";
    let mut tmp = tempfile().unwrap();
    tmp.write_all(CONTENTS).unwrap();
    let tmpfd = tmp.into_raw_fd();

    let offset: off_t = 5;
    lseek(tmpfd, offset, Whence::SeekSet).unwrap();

    let mut buf = [0u8; 7];
    ::read_exact(tmpfd, &mut buf);
    assert_eq!(b"f123456", &buf);

    close(tmpfd).unwrap();
}

#[cfg(any(target_os = "linux", target_os = "android"))]
#[test]
fn test_lseek64() {
    const CONTENTS: &[u8] = b"abcdef123456";
    let mut tmp = tempfile().unwrap();
    tmp.write_all(CONTENTS).unwrap();
    let tmpfd = tmp.into_raw_fd();

    lseek64(tmpfd, 5, Whence::SeekSet).unwrap();

    let mut buf = [0u8; 7];
    ::read_exact(tmpfd, &mut buf);
    assert_eq!(b"f123456", &buf);

    close(tmpfd).unwrap();
}

cfg_if!{
    if #[cfg(any(target_os = "android", target_os = "linux"))] {
        macro_rules! require_acct{
            () => {
                require_capability!(CAP_SYS_PACCT);
            }
        }
    } else if #[cfg(target_os = "freebsd")] {
        macro_rules! require_acct{
            () => {
                skip_if_not_root!("test_acct");
                skip_if_jailed!("test_acct");
            }
        }
    } else {
        macro_rules! require_acct{
            () => {
                skip_if_not_root!("test_acct");
            }
        }
    }
}

#[test]
fn test_acct() {
    use tempfile::NamedTempFile;
    use std::process::Command;
    use std::{thread, time};

    let _m = ::FORK_MTX.lock().expect("Mutex got poisoned by another test");
    require_acct!();

    let file = NamedTempFile::new().unwrap();
    let path = file.path().to_str().unwrap();

    acct::enable(path).unwrap();

    loop {
        Command::new("echo").arg("Hello world");
        let len = fs::metadata(path).unwrap().len();
        if len > 0 { break; }
        thread::sleep(time::Duration::from_millis(10));
    }
    acct::disable().unwrap();
}

#[test]
fn test_fpathconf_limited() {
    let f = tempfile().unwrap();
    // AFAIK, PATH_MAX is limited on all platforms, so it makes a good test
    let path_max = fpathconf(f.as_raw_fd(), PathconfVar::PATH_MAX);
    assert!(path_max.expect("fpathconf failed").expect("PATH_MAX is unlimited") > 0);
}

#[test]
fn test_pathconf_limited() {
    // AFAIK, PATH_MAX is limited on all platforms, so it makes a good test
    let path_max = pathconf("/", PathconfVar::PATH_MAX);
    assert!(path_max.expect("pathconf failed").expect("PATH_MAX is unlimited") > 0);
}

#[test]
fn test_sysconf_limited() {
    // AFAIK, OPEN_MAX is limited on all platforms, so it makes a good test
    let open_max = sysconf(SysconfVar::OPEN_MAX);
    assert!(open_max.expect("sysconf failed").expect("OPEN_MAX is unlimited") > 0);
}

#[cfg(target_os = "freebsd")]
#[test]
fn test_sysconf_unsupported() {
    // I know of no sysconf variables that are unsupported everywhere, but
    // _XOPEN_CRYPT is unsupported on FreeBSD 11.0, which is one of the platforms
    // we test.
    let open_max = sysconf(SysconfVar::_XOPEN_CRYPT);
    assert!(open_max.expect("sysconf failed").is_none())
}

// Test that we can create a pair of pipes.  No need to verify that they pass
// data; that's the domain of the OS, not nix.
#[test]
fn test_pipe() {
    let (fd0, fd1) = pipe().unwrap();
    let m0 = stat::SFlag::from_bits_truncate(stat::fstat(fd0).unwrap().st_mode);
    // S_IFIFO means it's a pipe
    assert_eq!(m0, SFlag::S_IFIFO);
    let m1 = stat::SFlag::from_bits_truncate(stat::fstat(fd1).unwrap().st_mode);
    assert_eq!(m1, SFlag::S_IFIFO);
}

// pipe2(2) is the same as pipe(2), except it allows setting some flags.  Check
// that we can set a flag.
#[test]
fn test_pipe2() {
    let (fd0, fd1) = pipe2(OFlag::O_CLOEXEC).unwrap();
    let f0 = FdFlag::from_bits_truncate(fcntl(fd0, FcntlArg::F_GETFD).unwrap());
    assert!(f0.contains(FdFlag::FD_CLOEXEC));
    let f1 = FdFlag::from_bits_truncate(fcntl(fd1, FcntlArg::F_GETFD).unwrap());
    assert!(f1.contains(FdFlag::FD_CLOEXEC));
}

#[test]
fn test_truncate() {
    let tempdir = tempfile::tempdir().unwrap();
    let path = tempdir.path().join("file");

    {
        let mut tmp = File::create(&path).unwrap();
        const CONTENTS: &[u8] = b"12345678";
        tmp.write_all(CONTENTS).unwrap();
    }

    truncate(&path, 4).unwrap();

    let metadata = fs::metadata(&path).unwrap();
    assert_eq!(4, metadata.len());
}

#[test]
fn test_ftruncate() {
    let tempdir = tempfile::tempdir().unwrap();
    let path = tempdir.path().join("file");

    let tmpfd = {
        let mut tmp = File::create(&path).unwrap();
        const CONTENTS: &[u8] = b"12345678";
        tmp.write_all(CONTENTS).unwrap();
        tmp.into_raw_fd()
    };

    ftruncate(tmpfd, 2).unwrap();
    close(tmpfd).unwrap();

    let metadata = fs::metadata(&path).unwrap();
    assert_eq!(2, metadata.len());
}

// Used in `test_alarm`.
static mut ALARM_CALLED: bool = false;

// Used in `test_alarm`.
pub extern fn alarm_signal_handler(raw_signal: libc::c_int) {
    assert_eq!(raw_signal, libc::SIGALRM, "unexpected signal: {}", raw_signal);
    unsafe { ALARM_CALLED = true };
}

#[test]
fn test_alarm() {
    let _m = ::SIGNAL_MTX.lock().expect("Mutex got poisoned by another test");

    let handler = SigHandler::Handler(alarm_signal_handler);
    let signal_action = SigAction::new(handler, SaFlags::SA_RESTART, SigSet::empty());
    let old_handler = unsafe {
        sigaction(Signal::SIGALRM, &signal_action)
            .expect("unable to set signal handler for alarm")
    };

    // Set an alarm.
    assert_eq!(alarm::set(60), None);

    // Overwriting an alarm should return the old alarm.
    assert_eq!(alarm::set(1), Some(60));

    // We should be woken up after 1 second by the alarm, so we'll sleep for 2
    // seconds to be sure.
    sleep(2);
    assert_eq!(unsafe { ALARM_CALLED }, true, "expected our alarm signal handler to be called");

    // Reset the signal.
    unsafe {
        sigaction(Signal::SIGALRM, &old_handler)
            .expect("unable to set signal handler for alarm");
    }
}

#[test]
fn test_canceling_alarm() {
    let _m = ::SIGNAL_MTX.lock().expect("Mutex got poisoned by another test");

    assert_eq!(alarm::cancel(), None);

    assert_eq!(alarm::set(60), None);
    assert_eq!(alarm::cancel(), Some(60));
}

#[test]
fn test_symlinkat() {
    let tempdir = tempfile::tempdir().unwrap();

    let target = tempdir.path().join("a");
    let linkpath = tempdir.path().join("b");
    symlinkat(&target, None, &linkpath).unwrap();
    assert_eq!(
        readlink(&linkpath).unwrap().to_str().unwrap(),
        target.to_str().unwrap()
    );

    let dirfd = open(tempdir.path(), OFlag::empty(), Mode::empty()).unwrap();
    let target = "c";
    let linkpath = "d";
    symlinkat(target, Some(dirfd), linkpath).unwrap();
    assert_eq!(
        readlink(&tempdir.path().join(linkpath))
            .unwrap()
            .to_str()
            .unwrap(),
        target
    );
}


#[test]
fn test_linkat_file() {
    let tempdir = tempfile::tempdir().unwrap();
    let oldfilename = "foo.txt";
    let oldfilepath = tempdir.path().join(oldfilename);

    let newfilename = "bar.txt";
    let newfilepath = tempdir.path().join(newfilename);

    // Create file
    File::create(&oldfilepath).unwrap();

    // Get file descriptor for base directory
    let dirfd = fcntl::open(tempdir.path(), fcntl::OFlag::empty(), stat::Mode::empty()).unwrap();

    // Attempt hard link file at relative path
    linkat(Some(dirfd), oldfilename, Some(dirfd), newfilename, LinkatFlags::SymlinkFollow).unwrap();
    assert!(newfilepath.exists());
}

#[cfg(target_os = "freebsd")]
#[test]
fn test_linkat_no_follow_symlink() {
    let tempdir = tempfile::tempdir().unwrap();
    let oldfilename = "foo.txt";
    let oldfilepath = tempdir.path().join(oldfilename);

    let symoldfilename = "symfoo.txt";
    let symoldfilepath = tempdir.path().join(symoldfilename);

    let newfilename = "nofollowsymbar.txt";
    let newfilepath = tempdir.path().join(newfilename);

    // Create file
    File::create(&oldfilepath).unwrap();

    // Create symlink to file
    symlinkat(&oldfilepath, None, &symoldfilepath).unwrap();

    // Get file descriptor for base directory
    let dirfd = fcntl::open(tempdir.path(), fcntl::OFlag::empty(), stat::Mode::empty()).unwrap();

    // Attempt link symlink of file at relative path
    linkat(Some(dirfd), symoldfilename, Some(dirfd), newfilename, LinkatFlags::NoSymlinkFollow).unwrap();

    // Assert newfile is actually a symlink to oldfile.
    assert_eq!(
        readlink(&newfilepath)
            .unwrap()
            .to_str()
            .unwrap(),
        oldfilepath.to_str().unwrap()
    );
}

#[test]
fn test_linkat_follow_symlink() {
    let tempdir = tempfile::tempdir().unwrap();
    let oldfilename = "foo.txt";
    let oldfilepath = tempdir.path().join(oldfilename);

    let symoldfilename = "symfoo.txt";
    let symoldfilepath = tempdir.path().join(symoldfilename);

    let newfilename = "nofollowsymbar.txt";
    let newfilepath = tempdir.path().join(newfilename);

    // Create file
    File::create(&oldfilepath).unwrap();

    // Create symlink to file
    symlinkat(&oldfilepath, None, &symoldfilepath).unwrap();

    // Get file descriptor for base directory
    let dirfd = fcntl::open(tempdir.path(), fcntl::OFlag::empty(), stat::Mode::empty()).unwrap();

    // Attempt link target of symlink of file at relative path
    linkat(Some(dirfd), symoldfilename, Some(dirfd), newfilename, LinkatFlags::SymlinkFollow).unwrap();

    let newfilestat = stat::stat(&newfilepath).unwrap();

    // Check the file type of the new link
    assert!((stat::SFlag::from_bits_truncate(newfilestat.st_mode) & SFlag::S_IFMT) ==  SFlag::S_IFREG);

    // Check the number of hard links to the original file
    assert_eq!(newfilestat.st_nlink, 2);
}

#[test]
fn test_unlinkat_dir_noremovedir() {
    let tempdir = tempfile::tempdir().unwrap();
    let dirname = "foo_dir";
    let dirpath = tempdir.path().join(dirname);

    // Create dir
    DirBuilder::new().recursive(true).create(&dirpath).unwrap();

    // Get file descriptor for base directory
    let dirfd = fcntl::open(tempdir.path(), fcntl::OFlag::empty(), stat::Mode::empty()).unwrap();

    // Attempt unlink dir at relative path without proper flag
    let err_result = unlinkat(Some(dirfd), dirname, UnlinkatFlags::NoRemoveDir).unwrap_err();
    assert!(err_result == Error::Sys(Errno::EISDIR) || err_result == Error::Sys(Errno::EPERM));
 }

#[test]
fn test_unlinkat_dir_removedir() {
    let tempdir = tempfile::tempdir().unwrap();
    let dirname = "foo_dir";
    let dirpath = tempdir.path().join(dirname);

    // Create dir
    DirBuilder::new().recursive(true).create(&dirpath).unwrap();

    // Get file descriptor for base directory
    let dirfd = fcntl::open(tempdir.path(), fcntl::OFlag::empty(), stat::Mode::empty()).unwrap();

    // Attempt unlink dir at relative path with proper flag
    unlinkat(Some(dirfd), dirname, UnlinkatFlags::RemoveDir).unwrap();
    assert!(!dirpath.exists());
 }

#[test]
fn test_unlinkat_file() {
    let tempdir = tempfile::tempdir().unwrap();
    let filename = "foo.txt";
    let filepath = tempdir.path().join(filename);

    // Create file
    File::create(&filepath).unwrap();

    // Get file descriptor for base directory
    let dirfd = fcntl::open(tempdir.path(), fcntl::OFlag::empty(), stat::Mode::empty()).unwrap();

    // Attempt unlink file at relative path
    unlinkat(Some(dirfd), filename, UnlinkatFlags::NoRemoveDir).unwrap();
    assert!(!filepath.exists());
 }

#[test]
fn test_access_not_existing() {
    let tempdir = tempfile::tempdir().unwrap();
    let dir = tempdir.path().join("does_not_exist.txt");
    assert_eq!(access(&dir, AccessFlags::F_OK).err().unwrap().as_errno().unwrap(),
               Errno::ENOENT);
}

#[test]
fn test_access_file_exists() {
    let tempdir = tempfile::tempdir().unwrap();
    let path  = tempdir.path().join("does_exist.txt");
    let _file = File::create(path.clone()).unwrap();
    assert!(access(&path, AccessFlags::R_OK | AccessFlags::W_OK).is_ok());
}