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
//! POSIX-style `*at` functions.
//!
//! The `dirfd` argument to these functions may be a file descriptor for a
//! directory, or the special value [`CWD`].
//!
//! [`cwd`]: crate::fs::cwd::CWD

use crate::fd::OwnedFd;
#[cfg(apple)]
use crate::fs::CloneFlags;
#[cfg(not(any(apple, target_os = "espidf", target_os = "wasi")))]
use crate::fs::FileType;
#[cfg(linux_kernel)]
use crate::fs::RenameFlags;
#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
use crate::fs::{Gid, Uid};
use crate::fs::{Mode, OFlags};
use crate::{backend, io, path};
use backend::fd::AsFd;
#[cfg(feature = "alloc")]
use {
    crate::ffi::{CStr, CString},
    crate::path::SMALL_PATH_BUFFER_SIZE,
    alloc::vec::Vec,
    backend::fd::BorrowedFd,
};
#[cfg(not(target_os = "espidf"))]
use {
    crate::fs::{Access, AtFlags, Stat, Timestamps},
    crate::timespec::Nsecs,
};

pub use backend::fs::types::{Dev, RawMode};

/// `UTIME_NOW` for use with [`utimensat`].
///
/// [`utimensat`]: crate::fs::utimensat
#[cfg(not(any(target_os = "espidf", target_os = "redox")))]
pub const UTIME_NOW: Nsecs = backend::c::UTIME_NOW as Nsecs;

/// `UTIME_OMIT` for use with [`utimensat`].
///
/// [`utimensat`]: crate::fs::utimensat
#[cfg(not(any(target_os = "espidf", target_os = "redox")))]
pub const UTIME_OMIT: Nsecs = backend::c::UTIME_OMIT as Nsecs;

/// `openat(dirfd, path, oflags, mode)`—Opens a file.
///
/// POSIX guarantees that `openat` will use the lowest unused file descriptor,
/// however it is not safe in general to rely on this, as file descriptors may
/// be unexpectedly allocated on other threads or in libraries.
///
/// The `Mode` argument is only significant when creating a file.
///
/// # References
///  - [POSIX]
///  - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/openat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/openat.2.html
#[inline]
pub fn openat<P: path::Arg, Fd: AsFd>(
    dirfd: Fd,
    path: P,
    oflags: OFlags,
    create_mode: Mode,
) -> io::Result<OwnedFd> {
    path.into_with_c_str(|path| {
        backend::fs::syscalls::openat(dirfd.as_fd(), path, oflags, create_mode)
    })
}

/// `readlinkat(fd, path)`—Reads the contents of a symlink.
///
/// If `reuse` already has available capacity, reuse it if possible.
///
/// # References
///  - [POSIX]
///  - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/readlinkat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/readlinkat.2.html
#[cfg(feature = "alloc")]
#[inline]
pub fn readlinkat<P: path::Arg, Fd: AsFd, B: Into<Vec<u8>>>(
    dirfd: Fd,
    path: P,
    reuse: B,
) -> io::Result<CString> {
    path.into_with_c_str(|path| _readlinkat(dirfd.as_fd(), path, reuse.into()))
}

#[cfg(feature = "alloc")]
#[allow(unsafe_code)]
fn _readlinkat(dirfd: BorrowedFd<'_>, path: &CStr, mut buffer: Vec<u8>) -> io::Result<CString> {
    buffer.clear();
    buffer.reserve(SMALL_PATH_BUFFER_SIZE);

    loop {
        let nread =
            backend::fs::syscalls::readlinkat(dirfd.as_fd(), path, buffer.spare_capacity_mut())?;

        debug_assert!(nread <= buffer.capacity());
        if nread < buffer.capacity() {
            // SAFETY: From the [documentation]:
            // "On success, these calls return the number of bytes placed in buf."
            //
            // [documentation]: https://man7.org/linux/man-pages/man2/readlinkat.2.html
            unsafe {
                buffer.set_len(nread);
            }

            // SAFETY:
            // - "readlink places the contents of the symbolic link pathname in the buffer
            //   buf"
            // - [POSIX definition 3.271: Pathname]: "A string that is used to identify a
            //   file."
            // - [POSIX definition 3.375: String]: "A contiguous sequence of bytes
            //   terminated by and including the first null byte."
            // - "readlink does not append a terminating null byte to buf."
            //
            // Thus, there will be no NUL bytes in the string.
            //
            // [POSIX definition 3.271: Pathname]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_271
            // [POSIX definition 3.375: String]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_375
            unsafe {
                return Ok(CString::from_vec_unchecked(buffer));
            }
        }

        buffer.reserve(buffer.capacity() + 1); // use `Vec` reallocation
                                               // strategy to grow capacity
                                               // exponentially
    }
}

/// `mkdirat(fd, path, mode)`—Creates a directory.
///
/// # References
///  - [POSIX]
///  - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/mkdirat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/mkdirat.2.html
#[inline]
pub fn mkdirat<P: path::Arg, Fd: AsFd>(dirfd: Fd, path: P, mode: Mode) -> io::Result<()> {
    path.into_with_c_str(|path| backend::fs::syscalls::mkdirat(dirfd.as_fd(), path, mode))
}

/// `linkat(old_dirfd, old_path, new_dirfd, new_path, flags)`—Creates a hard
/// link.
///
/// # References
///  - [POSIX]
///  - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/linkat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/linkat.2.html
#[cfg(not(target_os = "espidf"))]
#[inline]
pub fn linkat<P: path::Arg, Q: path::Arg, PFd: AsFd, QFd: AsFd>(
    old_dirfd: PFd,
    old_path: P,
    new_dirfd: QFd,
    new_path: Q,
    flags: AtFlags,
) -> io::Result<()> {
    old_path.into_with_c_str(|old_path| {
        new_path.into_with_c_str(|new_path| {
            backend::fs::syscalls::linkat(
                old_dirfd.as_fd(),
                old_path,
                new_dirfd.as_fd(),
                new_path,
                flags,
            )
        })
    })
}

/// `unlinkat(fd, path, flags)`—Unlinks a file or remove a directory.
///
/// With the [`REMOVEDIR`] flag, this removes a directory. This is in place
/// of a `rmdirat` function.
///
/// # References
///  - [POSIX]
///  - [Linux]
///
/// [`REMOVEDIR`]: AtFlags::REMOVEDIR
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/unlinkat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/unlinkat.2.html
#[cfg(not(target_os = "espidf"))]
#[inline]
pub fn unlinkat<P: path::Arg, Fd: AsFd>(dirfd: Fd, path: P, flags: AtFlags) -> io::Result<()> {
    path.into_with_c_str(|path| backend::fs::syscalls::unlinkat(dirfd.as_fd(), path, flags))
}

/// `renameat(old_dirfd, old_path, new_dirfd, new_path)`—Renames a file or
/// directory.
///
/// # References
///  - [POSIX]
///  - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/renameat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/renameat.2.html
#[inline]
pub fn renameat<P: path::Arg, Q: path::Arg, PFd: AsFd, QFd: AsFd>(
    old_dirfd: PFd,
    old_path: P,
    new_dirfd: QFd,
    new_path: Q,
) -> io::Result<()> {
    old_path.into_with_c_str(|old_path| {
        new_path.into_with_c_str(|new_path| {
            backend::fs::syscalls::renameat(
                old_dirfd.as_fd(),
                old_path,
                new_dirfd.as_fd(),
                new_path,
            )
        })
    })
}

/// `renameat2(old_dirfd, old_path, new_dirfd, new_path, flags)`—Renames a
/// file or directory.
///
/// # References
///  - [Linux]
///
/// [Linux]: https://man7.org/linux/man-pages/man2/renameat2.2.html
#[cfg(linux_kernel)]
#[inline]
#[doc(alias = "renameat2")]
pub fn renameat_with<P: path::Arg, Q: path::Arg, PFd: AsFd, QFd: AsFd>(
    old_dirfd: PFd,
    old_path: P,
    new_dirfd: QFd,
    new_path: Q,
    flags: RenameFlags,
) -> io::Result<()> {
    old_path.into_with_c_str(|old_path| {
        new_path.into_with_c_str(|new_path| {
            backend::fs::syscalls::renameat2(
                old_dirfd.as_fd(),
                old_path,
                new_dirfd.as_fd(),
                new_path,
                flags,
            )
        })
    })
}

/// `symlinkat(old_path, new_dirfd, new_path)`—Creates a symlink.
///
/// # References
///  - [POSIX]
///  - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/symlinkat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/symlinkat.2.html
#[inline]
pub fn symlinkat<P: path::Arg, Q: path::Arg, Fd: AsFd>(
    old_path: P,
    new_dirfd: Fd,
    new_path: Q,
) -> io::Result<()> {
    old_path.into_with_c_str(|old_path| {
        new_path.into_with_c_str(|new_path| {
            backend::fs::syscalls::symlinkat(old_path, new_dirfd.as_fd(), new_path)
        })
    })
}

/// `fstatat(dirfd, path, flags)`—Queries metadata for a file or directory.
///
/// [`Mode::from_raw_mode`] and [`FileType::from_raw_mode`] may be used to
/// interpret the `st_mode` field.
///
/// # References
///  - [POSIX]
///  - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/fstatat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/fstatat.2.html
/// [`Mode::from_raw_mode`]: crate::fs::Mode::from_raw_mode
/// [`FileType::from_raw_mode`]: crate::fs::FileType::from_raw_mode
#[cfg(not(target_os = "espidf"))]
#[inline]
#[doc(alias = "fstatat")]
pub fn statat<P: path::Arg, Fd: AsFd>(dirfd: Fd, path: P, flags: AtFlags) -> io::Result<Stat> {
    path.into_with_c_str(|path| backend::fs::syscalls::statat(dirfd.as_fd(), path, flags))
}

/// `faccessat(dirfd, path, access, flags)`—Tests permissions for a file or
/// directory.
///
/// On Linux before 5.8, this function uses the `faccessat` system call which
/// doesn't support any flags. This function emulates support for the
/// [`AtFlags::EACCESS`] flag by checking whether the uid and gid of the
/// process match the effective uid and gid, in which case the `EACCESS` flag
/// can be ignored. In Linux 5.8 and beyond `faccessat2` is used, which
/// supports flags.
///
/// # References
///  - [POSIX]
///  - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/faccessat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/faccessat.2.html
#[cfg(not(target_os = "espidf"))]
#[inline]
#[doc(alias = "faccessat")]
pub fn accessat<P: path::Arg, Fd: AsFd>(
    dirfd: Fd,
    path: P,
    access: Access,
    flags: AtFlags,
) -> io::Result<()> {
    path.into_with_c_str(|path| backend::fs::syscalls::accessat(dirfd.as_fd(), path, access, flags))
}

/// `utimensat(dirfd, path, times, flags)`—Sets file or directory timestamps.
///
/// # References
///  - [POSIX]
///  - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/utimensat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/utimensat.2.html
#[cfg(not(target_os = "espidf"))]
#[inline]
pub fn utimensat<P: path::Arg, Fd: AsFd>(
    dirfd: Fd,
    path: P,
    times: &Timestamps,
    flags: AtFlags,
) -> io::Result<()> {
    path.into_with_c_str(|path| backend::fs::syscalls::utimensat(dirfd.as_fd(), path, times, flags))
}

/// `fchmodat(dirfd, path, mode, flags)`—Sets file or directory permissions.
///
/// Platform support for flags varies widely, for example on Linux
/// [`AtFlags::SYMLINK_NOFOLLOW`] is not implemented and therefore
/// [`io::Errno::OPNOTSUPP`] will be returned.
///
/// # References
///  - [POSIX]
///  - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/fchmodat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/fchmodat.2.html
#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
#[inline]
#[doc(alias = "fchmodat")]
pub fn chmodat<P: path::Arg, Fd: AsFd>(
    dirfd: Fd,
    path: P,
    mode: Mode,
    flags: AtFlags,
) -> io::Result<()> {
    path.into_with_c_str(|path| backend::fs::syscalls::chmodat(dirfd.as_fd(), path, mode, flags))
}

/// `fclonefileat(src, dst_dir, dst, flags)`—Efficiently copies between files.
///
/// # References
///  - [Apple]
///
/// [Apple]: https://opensource.apple.com/source/xnu/xnu-3789.21.4/bsd/man/man2/clonefile.2.auto.html
#[cfg(apple)]
#[inline]
pub fn fclonefileat<Fd: AsFd, DstFd: AsFd, P: path::Arg>(
    src: Fd,
    dst_dir: DstFd,
    dst: P,
    flags: CloneFlags,
) -> io::Result<()> {
    dst.into_with_c_str(|dst| {
        backend::fs::syscalls::fclonefileat(src.as_fd(), dst_dir.as_fd(), dst, flags)
    })
}

/// `mknodat(dirfd, path, mode, dev)`—Creates special or normal files.
///
/// # References
///  - [POSIX]
///  - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/mknodat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/mknodat.2.html
#[cfg(not(any(apple, target_os = "espidf", target_os = "wasi")))]
#[inline]
pub fn mknodat<P: path::Arg, Fd: AsFd>(
    dirfd: Fd,
    path: P,
    file_type: FileType,
    mode: Mode,
    dev: Dev,
) -> io::Result<()> {
    path.into_with_c_str(|path| {
        backend::fs::syscalls::mknodat(dirfd.as_fd(), path, file_type, mode, dev)
    })
}

/// `fchownat(dirfd, path, owner, group, flags)`—Sets file or directory
/// ownership.
///
/// # References
///  - [POSIX]
///  - [Linux]
///
/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/fchownat.html
/// [Linux]: https://man7.org/linux/man-pages/man2/fchownat.2.html
#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
#[inline]
#[doc(alias = "fchownat")]
pub fn chownat<P: path::Arg, Fd: AsFd>(
    dirfd: Fd,
    path: P,
    owner: Option<Uid>,
    group: Option<Gid>,
    flags: AtFlags,
) -> io::Result<()> {
    path.into_with_c_str(|path| {
        backend::fs::syscalls::chownat(dirfd.as_fd(), path, owner, group, flags)
    })
}