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
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
use std::io;
use std::mem;
use std::ffi::{OsString, CStr};
use std::fs::{File, read_link};
use std::os::unix::io::{AsRawFd, RawFd, FromRawFd, IntoRawFd};
use std::os::unix::ffi::{OsStringExt};
use std::path::{PathBuf};

use libc;
use metadata::{self, Metadata};
use list::{DirIter, open_dir};

use {Dir, AsPath};

impl Dir {
    /// Creates a directory descriptor that resolves paths relative to current
    /// working directory (AT_FDCWD)
    #[deprecated(since="0.1.15", note="\
        Use `Dir::open(\".\")` instead. \
        Dir::cwd() doesn't open actual file descriptor and uses magic value \
        instead which resolves to current dir on any syscall invocation. \
        This is usually counter-intuitive and yields a broken \
        file descriptor when using `Dir::as_raw_fd`. \
        Will be removed in version v0.2 of the library.")]
    pub fn cwd() -> Dir {
        Dir(libc::AT_FDCWD)
    }

    /// Open a directory descriptor at specified path
    // TODO(tailhook) maybe accept only absolute paths?
    pub fn open<P: AsPath>(path: P) -> io::Result<Dir> {
        Dir::_open(to_cstr(path)?.as_ref())
    }

    fn _open(path: &CStr) -> io::Result<Dir> {
        let fd = unsafe {
            libc::open(path.as_ptr(), libc::O_PATH|libc::O_CLOEXEC)
        };
        if fd < 0 {
            Err(io::Error::last_os_error())
        } else {
            Ok(Dir(fd))
        }
    }

    /// List subdirectory of this dir
    ///
    /// You can list directory itself if `"."` is specified as path.
    pub fn list_dir<P: AsPath>(&self, path: P) -> io::Result<DirIter> {
        open_dir(self, to_cstr(path)?.as_ref())
    }

    /// Open subdirectory
    pub fn sub_dir<P: AsPath>(&self, path: P) -> io::Result<Dir> {
        self._sub_dir(to_cstr(path)?.as_ref())
    }

    fn _sub_dir(&self, path: &CStr) -> io::Result<Dir> {
        let fd = unsafe {
            libc::openat(self.0,
                        path.as_ptr(),
                        libc::O_PATH|libc::O_CLOEXEC|libc::O_NOFOLLOW)
        };
        if fd < 0 {
            Err(io::Error::last_os_error())
        } else {
            Ok(Dir(fd))
        }
    }

    /// Read link in this directory
    pub fn read_link<P: AsPath>(&self, path: P) -> io::Result<PathBuf> {
        self._read_link(to_cstr(path)?.as_ref())
    }

    fn _read_link(&self, path: &CStr) -> io::Result<PathBuf> {
        let mut buf = vec![0u8; 4096];
        let res = unsafe {
            libc::readlinkat(self.0,
                        path.as_ptr(),
                        buf.as_mut_ptr() as *mut libc::c_char, buf.len())
        };
        if res < 0 {
            Err(io::Error::last_os_error())
        } else {
            buf.truncate(res as usize);
            Ok(OsString::from_vec(buf).into())
        }
    }

    /// Open file for reading in this directory
    pub fn open_file<P: AsPath>(&self, path: P) -> io::Result<File> {
        self._open_file(to_cstr(path)?.as_ref(),
            libc::O_RDONLY, 0)
    }

    /// Open file for writing, create if necessary, truncate on open
    pub fn write_file<P: AsPath>(&self, path: P, mode: libc::mode_t)
        -> io::Result<File>
    {
        self._open_file(to_cstr(path)?.as_ref(),
            libc::O_CREAT|libc::O_WRONLY|libc::O_TRUNC,
            mode)
    }

    /// Open file for append, create if necessary
    pub fn append_file<P: AsPath>(&self, path: P, mode: libc::mode_t)
        -> io::Result<File>
    {
        self._open_file(to_cstr(path)?.as_ref(),
            libc::O_CREAT|libc::O_WRONLY|libc::O_APPEND,
            mode)
    }

    /// Create file for writing (and truncate) in this directory
    ///
    /// Deprecated alias for `write_file`
    #[deprecated(since="0.1.7", note="please use `write_file` instead")]
    pub fn create_file<P: AsPath>(&self, path: P, mode: libc::mode_t)
        -> io::Result<File>
    {
        self._open_file(to_cstr(path)?.as_ref(),
            libc::O_CREAT|libc::O_WRONLY|libc::O_TRUNC,
            mode)
    }

    /// Create a tmpfile in this directory which isn't linked to any filename
    ///
    /// This works by passing `O_TMPFILE` into the openat call. The flag is
    /// supported only on linux. So this function always returns error on
    /// such systems.
    ///
    /// **WARNING!** On glibc < 2.22 file permissions of the newly created file
    /// may be arbitrary. Consider chowning after creating a file.
    ///
    /// Note: It may be unclear why creating unnamed file requires a dir. There
    /// are two reasons:
    ///
    /// 1. It's created (and occupies space) on a real filesystem, so the
    ///    directory is a way to find out which filesystem to attach file to
    /// 2. This method is mostly needed to initialize the file then link it
    ///    using ``link_file_at`` to the real directory entry. When linking
    ///    it must be linked into the same filesystem. But because for most
    ///    programs finding out filesystem layout is an overkill the rule of
    ///    thumb is to create a file in the the target directory.
    ///
    /// Currently, we recommend to fallback on any error if this operation
    /// can't be accomplished rather than relying on specific error codes,
    /// because semantics of errors are very ugly.
    #[cfg(target_os="linux")]
    pub fn new_unnamed_file(&self, mode: libc::mode_t)
        -> io::Result<File>
    {
        self._open_file(unsafe { CStr::from_bytes_with_nul_unchecked(b".\0") },
            libc::O_TMPFILE|libc::O_WRONLY,
            mode)
    }

    /// Create a tmpfile in this directory which isn't linked to any filename
    ///
    /// This works by passing `O_TMPFILE` into the openat call. The flag is
    /// supported only on linux. So this function always returns error on
    /// such systems.
    ///
    /// Note: It may be unclear why creating unnamed file requires a dir. There
    /// are two reasons:
    ///
    /// 1. It's created (and occupies space) on a real filesystem, so the
    ///    directory is a way to find out which filesystem to attach file to
    /// 2. This method is mostly needed to initialize the file then link it
    ///    using ``link_file_at`` to the real directory entry. When linking
    ///    it must be linked into the same filesystem. But because for most
    ///    programs finding out filesystem layout is an overkill the rule of
    ///    thumb is to create a file in the the target directory.
    ///
    /// Currently, we recommend to fallback on any error if this operation
    /// can't be accomplished rather than relying on specific error codes,
    /// because semantics of errors are very ugly.
    #[cfg(not(target_os="linux"))]
    pub fn new_unnamed_file<P: AsPath>(&self, _mode: libc::mode_t)
        -> io::Result<File>
    {
        Err(io::Error::new(io::ErrorKind::Other,
            "creating unnamed tmpfiles is only supported on linux"))
    }

    /// Link open file to a specified path
    ///
    /// This is used with ``new_unnamed_file()`` to create and initialize the
    /// file before linking it into a filesystem. This requires `/proc` to be
    /// mounted and works **only on linux**.
    ///
    /// On systems other than linux this always returns error. It's expected
    /// that in most cases this methos is not called if ``new_unnamed_file``
    /// fails. But in obscure scenarios where `/proc` is not mounted this
    /// method may fail even on linux. So your code should be able to fallback
    /// to a named file if this method fails too.
    #[cfg(target_os="linux")]
    pub fn link_file_at<F: AsRawFd, P: AsPath>(&self, file: &F, path: P)
        -> io::Result<()>
    {
        let fd_path = format!("/proc/self/fd/{}", file.as_raw_fd());
        _hardlink(&Dir(libc::AT_FDCWD), to_cstr(fd_path)?.as_ref(),
            &self, to_cstr(path)?.as_ref(),
            libc::AT_SYMLINK_FOLLOW)
    }

    /// Link open file to a specified path
    ///
    /// This is used with ``new_unnamed_file()`` to create and initialize the
    /// file before linking it into a filesystem. This requires `/proc` to be
    /// mounted and works **only on linux**.
    ///
    /// On systems other than linux this always returns error. It's expected
    /// that in most cases this methos is not called if ``new_unnamed_file``
    /// fails. But in obscure scenarios where `/proc` is not mounted this
    /// method may fail even on linux. So your code should be able to fallback
    /// to a named file if this method fails too.
    #[cfg(not(target_os="linux"))]
    pub fn link_file_at<F: AsRawFd, P: AsPath>(&self, _file: F, _path: P)
        -> io::Result<()>
    {
        Err(io::Error::new(io::ErrorKind::Other,
            "linking unnamed fd to directories is only supported on linux"))
    }

    /// Create file if not exists, fail if exists
    ///
    /// This function checks existence and creates file atomically with
    /// respect to other threads and processes.
    ///
    /// Technically it means passing `O_EXCL` flag to open.
    pub fn new_file<P: AsPath>(&self, path: P, mode: libc::mode_t)
        -> io::Result<File>
    {
        self._open_file(to_cstr(path)?.as_ref(),
            libc::O_CREAT|libc::O_EXCL|libc::O_WRONLY,
            mode)
    }

    /// Open file for reading and writing without truncation, create if needed
    pub fn update_file<P: AsPath>(&self, path: P, mode: libc::mode_t)
        -> io::Result<File>
    {
        self._open_file(to_cstr(path)?.as_ref(),
            libc::O_CREAT|libc::O_RDWR,
            mode)
    }

    fn _open_file(&self, path: &CStr, flags: libc::c_int, mode: libc::mode_t)
        -> io::Result<File>
    {
        unsafe {
            let res = libc::openat(self.0, path.as_ptr(),
                            flags|libc::O_CLOEXEC|libc::O_NOFOLLOW,
                            mode as libc::c_uint);
            if res < 0 {
                Err(io::Error::last_os_error())
            } else {
                Ok(File::from_raw_fd(res))
            }
        }
    }

    /// Make a symlink in this directory
    ///
    /// Note: the order of arguments differ from `symlinkat`
    pub fn symlink<P: AsPath, R: AsPath>(&self, path: P, value: R)
        -> io::Result<()>
    {
        self._symlink(to_cstr(path)?.as_ref(), to_cstr(value)?.as_ref())
    }
    fn _symlink(&self, path: &CStr, link: &CStr) -> io::Result<()> {
        unsafe {
            let res = libc::symlinkat(link.as_ptr(),
                self.0, path.as_ptr());
            if res < 0 {
                Err(io::Error::last_os_error())
            } else {
                Ok(())
            }
        }
    }

    /// Create a subdirectory in this directory
    pub fn create_dir<P: AsPath>(&self, path: P, mode: libc::mode_t)
        -> io::Result<()>
    {
        self._create_dir(to_cstr(path)?.as_ref(), mode)
    }
    fn _create_dir(&self, path: &CStr, mode: libc::mode_t) -> io::Result<()> {
        unsafe {
            let res = libc::mkdirat(self.0, path.as_ptr(), mode);
            if res < 0 {
                Err(io::Error::last_os_error())
            } else {
                Ok(())
            }
        }
    }

    /// Rename a file in this directory to another name (keeping same dir)
    pub fn local_rename<P: AsPath, R: AsPath>(&self, old: P, new: R)
        -> io::Result<()>
    {
        rename(self, to_cstr(old)?.as_ref(), self, to_cstr(new)?.as_ref())
    }

    /// Similar to `local_rename` but atomically swaps both paths
    ///
    /// Only supported on Linux.
    #[cfg(target_os="linux")]
    pub fn local_exchange<P: AsPath, R: AsPath>(&self, old: P, new: R)
        -> io::Result<()>
    {
        rename_flags(self, to_cstr(old)?.as_ref(),
            self, to_cstr(new)?.as_ref(),
            libc::RENAME_EXCHANGE)
    }

    /// Remove a subdirectory in this directory
    ///
    /// Note only empty directory may be removed
    pub fn remove_dir<P: AsPath>(&self, path: P)
        -> io::Result<()>
    {
        self._unlink(to_cstr(path)?.as_ref(), libc::AT_REMOVEDIR)
    }
    /// Remove a file in this directory
    pub fn remove_file<P: AsPath>(&self, path: P)
        -> io::Result<()>
    {
        self._unlink(to_cstr(path)?.as_ref(), 0)
    }
    fn _unlink(&self, path: &CStr, flags: libc::c_int) -> io::Result<()> {
        unsafe {
            let res = libc::unlinkat(self.0, path.as_ptr(), flags);
            if res < 0 {
                Err(io::Error::last_os_error())
            } else {
                Ok(())
            }
        }
    }

    /// Get the path of this directory (if possible)
    ///
    /// This uses symlinks in `/proc/self`, they sometimes may not be
    /// available so use with care.
    pub fn recover_path(&self) -> io::Result<PathBuf> {
        let fd = self.0;
        if fd != libc::AT_FDCWD {
            read_link(format!("/proc/self/fd/{}", fd))
        } else {
            read_link("/proc/self/cwd")
        }
    }

    /// Returns metadata of an entry in this directory
    pub fn metadata<P: AsPath>(&self, path: P) -> io::Result<Metadata> {
        self._stat(to_cstr(path)?.as_ref(), libc::AT_SYMLINK_NOFOLLOW)
    }
    fn _stat(&self, path: &CStr, flags: libc::c_int) -> io::Result<Metadata> {
        unsafe {
            let mut stat = mem::zeroed();
            let res = libc::fstatat(self.0, path.as_ptr(),
                &mut stat, flags);
            if res < 0 {
                Err(io::Error::last_os_error())
            } else {
                Ok(metadata::new(stat))
            }
        }
    }

}

/// Rename (move) a file between directories
///
/// Files must be on a single filesystem anyway. This funtion does **not**
/// fallback to copying if needed.
pub fn rename<P, R>(old_dir: &Dir, old: P, new_dir: &Dir, new: R)
    -> io::Result<()>
    where P: AsPath, R: AsPath,
{
    _rename(old_dir, to_cstr(old)?.as_ref(), new_dir, to_cstr(new)?.as_ref())
}

fn _rename(old_dir: &Dir, old: &CStr, new_dir: &Dir, new: &CStr)
    -> io::Result<()>
{
    unsafe {
        let res = libc::renameat(old_dir.0, old.as_ptr(),
            new_dir.0, new.as_ptr());
        if res < 0 {
            Err(io::Error::last_os_error())
        } else {
            Ok(())
        }
    }
}

/// Create a hardlink to a file
///
/// Files must be on a single filesystem even if they are in different
/// directories.
///
/// Note: by default ``linkat`` syscall doesn't resolve symbolic links, and
/// it's also behavior of this function. It's recommended to resolve symlinks
/// manually if needed.
pub fn hardlink<P, R>(old_dir: &Dir, old: P, new_dir: &Dir, new: R)
    -> io::Result<()>
    where P: AsPath, R: AsPath,
{
    _hardlink(old_dir, to_cstr(old)?.as_ref(),
              new_dir, to_cstr(new)?.as_ref(),
              0)
}

fn _hardlink(old_dir: &Dir, old: &CStr, new_dir: &Dir, new: &CStr,
             flags: libc::c_int)
    -> io::Result<()>
{
    unsafe {
        let res = libc::linkat(old_dir.0, old.as_ptr(),
            new_dir.0, new.as_ptr(), flags);
        if res < 0 {
            Err(io::Error::last_os_error())
        } else {
            Ok(())
        }
    }
}

/// Rename (move) a file between directories with flags
///
/// Files must be on a single filesystem anyway. This funtion does **not**
/// fallback to copying if needed.
///
/// Only supported on Linux.
#[cfg(target_os="linux")]
pub fn rename_flags<P, R>(old_dir: &Dir, old: P, new_dir: &Dir, new: R,
    flags: libc::c_int)
    -> io::Result<()>
    where P: AsPath, R: AsPath,
{
    _rename_flags(old_dir, to_cstr(old)?.as_ref(),
        new_dir, to_cstr(new)?.as_ref(),
        flags)
}

#[cfg(target_os="linux")]
fn _rename_flags(old_dir: &Dir, old: &CStr, new_dir: &Dir, new: &CStr,
    flags: libc::c_int)
    -> io::Result<()>
{
    unsafe {
        let res = libc::syscall(
            libc::SYS_renameat2,
            old_dir.0, old.as_ptr(),
            new_dir.0, new.as_ptr(), flags);
        if res < 0 {
            Err(io::Error::last_os_error())
        } else {
            Ok(())
        }
    }
}

impl AsRawFd for Dir {
    #[inline]
    fn as_raw_fd(&self) -> RawFd {
        self.0
    }
}

impl FromRawFd for Dir {
    #[inline]
    unsafe fn from_raw_fd(fd: RawFd) -> Dir {
        Dir(fd)
    }
}

impl IntoRawFd for Dir {
    #[inline]
    fn into_raw_fd(self) -> RawFd {
        let result = self.0;
        mem::forget(self);
        return result;
    }
}

impl Drop for Dir {
    fn drop(&mut self) {
        let fd = self.0;
        if fd != libc::AT_FDCWD {
            unsafe {
                libc::close(fd);
            }
        }
    }
}

fn to_cstr<P: AsPath>(path: P) -> io::Result<P::Buffer> {
    path.to_path()
    .ok_or_else(|| {
        io::Error::new(io::ErrorKind::InvalidInput,
                       "nul byte in file name")
    })
}

#[cfg(test)]
mod test {
    use std::io::{Read};
    use std::path::Path;
    use std::os::unix::io::{FromRawFd, IntoRawFd};
    use {Dir};

    #[test]
    fn test_open_ok() {
        assert!(Dir::open("src").is_ok());
    }

    #[test]
    fn test_open_file() {
        Dir::open("src/lib.rs").unwrap();
    }

    #[test]
    fn test_read_file() {
        let dir = Dir::open("src").unwrap();
        let mut buf = String::new();
        dir.open_file("lib.rs").unwrap()
            .read_to_string(&mut buf).unwrap();
        assert!(buf.find("extern crate libc;").is_some());
    }

    #[test]
    fn test_from_into() {
        let dir = Dir::open("src").unwrap();
        let dir = unsafe { Dir::from_raw_fd(dir.into_raw_fd()) };
        let mut buf = String::new();
        dir.open_file("lib.rs").unwrap()
            .read_to_string(&mut buf).unwrap();
        assert!(buf.find("extern crate libc;").is_some());
    }

    #[test]
    #[should_panic(expected="No such file or directory")]
    fn test_open_no_dir() {
        Dir::open("src/some-non-existent-file").unwrap();
    }

    #[test]
    fn test_list() {
        let dir = Dir::open("src").unwrap();
        let me = dir.list_dir(".").unwrap();
        assert!(me.collect::<Result<Vec<_>, _>>().unwrap()
                .iter().find(|x| {
                    x.file_name() == Path::new("lib.rs").as_os_str()
                })
                .is_some());
    }
}