std/sys/pal/unix/
fd.rs

Help
1#![unstable(reason = "not public", issue = "none", feature = "fd")]
2
3#[cfg(test)]
4mod tests;
5
6#[cfg(not(any(
7    target_os = "linux",
8    target_os = "l4re",
9    target_os = "android",
10    target_os = "hurd",
11)))]
12use libc::off_t as off64_t;
13#[cfg(any(
14    target_os = "android",
15    target_os = "linux",
16    target_os = "l4re",
17    target_os = "hurd",
18))]
19use libc::off64_t;
20
21use crate::cmp;
22use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut, Read};
23use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
24use crate::sys::cvt;
25use crate::sys_common::{AsInner, FromInner, IntoInner};
26
27#[derive(Debug)]
28pub struct FileDesc(OwnedFd);
29
30// The maximum read limit on most POSIX-like systems is `SSIZE_MAX`,
31// with the man page quoting that if the count of bytes to read is
32// greater than `SSIZE_MAX` the result is "unspecified".
33//
34// On Apple targets however, apparently the 64-bit libc is either buggy or
35// intentionally showing odd behavior by rejecting any read with a size
36// larger than or equal to INT_MAX. To handle both of these the read
37// size is capped on both platforms.
38const READ_LIMIT: usize = if cfg!(target_vendor = "apple") {
39    libc::c_int::MAX as usize - 1
40} else {
41    libc::ssize_t::MAX as usize
42};
43
44#[cfg(any(
45    target_os = "dragonfly",
46    target_os = "freebsd",
47    target_os = "netbsd",
48    target_os = "openbsd",
49    target_vendor = "apple",
50))]
51const fn max_iov() -> usize {
52    libc::IOV_MAX as usize
53}
54
55#[cfg(any(
56    target_os = "android",
57    target_os = "emscripten",
58    target_os = "linux",
59    target_os = "nto",
60))]
61const fn max_iov() -> usize {
62    libc::UIO_MAXIOV as usize
63}
64
65#[cfg(not(any(
66    target_os = "android",
67    target_os = "dragonfly",
68    target_os = "emscripten",
69    target_os = "freebsd",
70    target_os = "linux",
71    target_os = "netbsd",
72    target_os = "nto",
73    target_os = "openbsd",
74    target_os = "horizon",
75    target_os = "vita",
76    target_vendor = "apple",
77)))]
78const fn max_iov() -> usize {
79    16 // The minimum value required by POSIX.
80}
81
82impl FileDesc {
83    #[inline]
84    pub fn try_clone(&self) -> io::Result<Self> {
85        self.duplicate()
86    }
87
88    pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
89        let ret = cvt(unsafe {
90            libc::read(
91                self.as_raw_fd(),
92                buf.as_mut_ptr() as *mut libc::c_void,
93                cmp::min(buf.len(), READ_LIMIT),
94            )
95        })?;
96        Ok(ret as usize)
97    }
98
99    #[cfg(not(any(
100        target_os = "espidf",
101        target_os = "horizon",
102        target_os = "vita",
103        target_os = "nuttx"
104    )))]
105    pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
106        let ret = cvt(unsafe {
107            libc::readv(
108                self.as_raw_fd(),
109                bufs.as_mut_ptr() as *mut libc::iovec as *const libc::iovec,
110                cmp::min(bufs.len(), max_iov()) as libc::c_int,
111            )
112        })?;
113        Ok(ret as usize)
114    }
115
116    #[cfg(any(
117        target_os = "espidf",
118        target_os = "horizon",
119        target_os = "vita",
120        target_os = "nuttx"
121    ))]
122    pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
123        io::default_read_vectored(|b| self.read(b), bufs)
124    }
125
126    #[inline]
127    pub fn is_read_vectored(&self) -> bool {
128        cfg!(not(any(
129            target_os = "espidf",
130            target_os = "horizon",
131            target_os = "vita",
132            target_os = "nuttx"
133        )))
134    }
135
136    pub fn read_to_end(&self, buf: &mut Vec<u8>) -> io::Result<usize> {
137        let mut me = self;
138        (&mut me).read_to_end(buf)
139    }
140
141    #[cfg_attr(target_os = "vxworks", allow(unused_unsafe))]
142    pub fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
143        #[cfg(not(any(
144            all(target_os = "linux", not(target_env = "musl")),
145            target_os = "android",
146            target_os = "hurd"
147        )))]
148        use libc::pread as pread64;
149        #[cfg(any(
150            all(target_os = "linux", not(target_env = "musl")),
151            target_os = "android",
152            target_os = "hurd"
153        ))]
154        use libc::pread64;
155
156        unsafe {
157            cvt(pread64(
158                self.as_raw_fd(),
159                buf.as_mut_ptr() as *mut libc::c_void,
160                cmp::min(buf.len(), READ_LIMIT),
161                offset as off64_t,
162            ))
163            .map(|n| n as usize)
164        }
165    }
166
167    pub fn read_buf(&self, mut cursor: BorrowedCursor<'_>) -> io::Result<()> {
168        let ret = cvt(unsafe {
169            libc::read(
170                self.as_raw_fd(),
171                cursor.as_mut().as_mut_ptr() as *mut libc::c_void,
172                cmp::min(cursor.capacity(), READ_LIMIT),
173            )
174        })?;
175
176        // Safety: `ret` bytes were written to the initialized portion of the buffer
177        unsafe {
178            cursor.advance_unchecked(ret as usize);
179        }
180        Ok(())
181    }
182
183    #[cfg(any(
184        target_os = "aix",
185        target_os = "dragonfly", // DragonFly 1.5
186        target_os = "emscripten",
187        target_os = "freebsd",
188        target_os = "fuchsia",
189        target_os = "hurd",
190        target_os = "illumos",
191        target_os = "linux",
192        target_os = "netbsd",
193        target_os = "openbsd", // OpenBSD 2.7
194    ))]
195    pub fn read_vectored_at(&self, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io::Result<usize> {
196        let ret = cvt(unsafe {
197            libc::preadv(
198                self.as_raw_fd(),
199                bufs.as_mut_ptr() as *mut libc::iovec as *const libc::iovec,
200                cmp::min(bufs.len(), max_iov()) as libc::c_int,
201                offset as _,
202            )
203        })?;
204        Ok(ret as usize)
205    }
206
207    #[cfg(not(any(
208        target_os = "aix",
209        target_os = "android",
210        target_os = "dragonfly",
211        target_os = "emscripten",
212        target_os = "freebsd",
213        target_os = "fuchsia",
214        target_os = "hurd",
215        target_os = "illumos",
216        target_os = "linux",
217        target_os = "netbsd",
218        target_os = "openbsd",
219        target_vendor = "apple",
220    )))]
221    pub fn read_vectored_at(&self, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io::Result<usize> {
222        io::default_read_vectored(|b| self.read_at(b, offset), bufs)
223    }
224
225    // We support some old Android versions that do not have `preadv` in libc,
226    // so we use weak linkage and fallback to a direct syscall if not available.
227    //
228    // On 32-bit targets, we don't want to deal with weird ABI issues around
229    // passing 64-bits parameters to syscalls, so we fallback to the default
230    // implementation if `preadv` is not available.
231    #[cfg(all(target_os = "android", target_pointer_width = "64"))]
232    pub fn read_vectored_at(&self, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io::Result<usize> {
233        super::weak::syscall! {
234            fn preadv(
235                fd: libc::c_int,
236                iovec: *const libc::iovec,
237                n_iovec: libc::c_int,
238                offset: off64_t
239            ) -> isize
240        }
241
242        let ret = cvt(unsafe {
243            preadv(
244                self.as_raw_fd(),
245                bufs.as_mut_ptr() as *mut libc::iovec as *const libc::iovec,
246                cmp::min(bufs.len(), max_iov()) as libc::c_int,
247                offset as _,
248            )
249        })?;
250        Ok(ret as usize)
251    }
252
253    #[cfg(all(target_os = "android", target_pointer_width = "32"))]
254    pub fn read_vectored_at(&self, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io::Result<usize> {
255        super::weak::weak!(fn preadv64(libc::c_int, *const libc::iovec, libc::c_int, off64_t) -> isize);
256
257        match preadv64.get() {
258            Some(preadv) => {
259                let ret = cvt(unsafe {
260                    preadv(
261                        self.as_raw_fd(),
262                        bufs.as_mut_ptr() as *mut libc::iovec as *const libc::iovec,
263                        cmp::min(bufs.len(), max_iov()) as libc::c_int,
264                        offset as _,
265                    )
266                })?;
267                Ok(ret as usize)
268            }
269            None => io::default_read_vectored(|b| self.read_at(b, offset), bufs),
270        }
271    }
272
273    // We support old MacOS, iOS, watchOS, tvOS and visionOS. `preadv` was added in the following
274    // Apple OS versions:
275    // ios 14.0
276    // tvos 14.0
277    // macos 11.0
278    // watchos 7.0
279    //
280    // These versions may be newer than the minimum supported versions of OS's we support so we must
281    // use "weak" linking.
282    #[cfg(target_vendor = "apple")]
283    pub fn read_vectored_at(&self, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io::Result<usize> {
284        super::weak::weak!(fn preadv(libc::c_int, *const libc::iovec, libc::c_int, off64_t) -> isize);
285
286        match preadv.get() {
287            Some(preadv) => {
288                let ret = cvt(unsafe {
289                    preadv(
290                        self.as_raw_fd(),
291                        bufs.as_mut_ptr() as *mut libc::iovec as *const libc::iovec,
292                        cmp::min(bufs.len(), max_iov()) as libc::c_int,
293                        offset as _,
294                    )
295                })?;
296                Ok(ret as usize)
297            }
298            None => io::default_read_vectored(|b| self.read_at(b, offset), bufs),
299        }
300    }
301
302    pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
303        let ret = cvt(unsafe {
304            libc::write(
305                self.as_raw_fd(),
306                buf.as_ptr() as *const libc::c_void,
307                cmp::min(buf.len(), READ_LIMIT),
308            )
309        })?;
310        Ok(ret as usize)
311    }
312
313    #[cfg(not(any(
314        target_os = "espidf",
315        target_os = "horizon",
316        target_os = "vita",
317        target_os = "nuttx"
318    )))]
319    pub fn write_vectored(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
320        let ret = cvt(unsafe {
321            libc::writev(
322                self.as_raw_fd(),
323                bufs.as_ptr() as *const libc::iovec,
324                cmp::min(bufs.len(), max_iov()) as libc::c_int,
325            )
326        })?;
327        Ok(ret as usize)
328    }
329
330    #[cfg(any(
331        target_os = "espidf",
332        target_os = "horizon",
333        target_os = "vita",
334        target_os = "nuttx"
335    ))]
336    pub fn write_vectored(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
337        io::default_write_vectored(|b| self.write(b), bufs)
338    }
339
340    #[inline]
341    pub fn is_write_vectored(&self) -> bool {
342        cfg!(not(any(
343            target_os = "espidf",
344            target_os = "horizon",
345            target_os = "vita",
346            target_os = "nuttx"
347        )))
348    }
349
350    #[cfg_attr(target_os = "vxworks", allow(unused_unsafe))]
351    pub fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
352        #[cfg(not(any(
353            all(target_os = "linux", not(target_env = "musl")),
354            target_os = "android",
355            target_os = "hurd"
356        )))]
357        use libc::pwrite as pwrite64;
358        #[cfg(any(
359            all(target_os = "linux", not(target_env = "musl")),
360            target_os = "android",
361            target_os = "hurd"
362        ))]
363        use libc::pwrite64;
364
365        unsafe {
366            cvt(pwrite64(
367                self.as_raw_fd(),
368                buf.as_ptr() as *const libc::c_void,
369                cmp::min(buf.len(), READ_LIMIT),
370                offset as off64_t,
371            ))
372            .map(|n| n as usize)
373        }
374    }
375
376    #[cfg(any(
377        target_os = "aix",
378        target_os = "dragonfly", // DragonFly 1.5
379        target_os = "emscripten",
380        target_os = "freebsd",
381        target_os = "fuchsia",
382        target_os = "hurd",
383        target_os = "illumos",
384        target_os = "linux",
385        target_os = "netbsd",
386        target_os = "openbsd", // OpenBSD 2.7
387    ))]
388    pub fn write_vectored_at(&self, bufs: &[IoSlice<'_>], offset: u64) -> io::Result<usize> {
389        let ret = cvt(unsafe {
390            libc::pwritev(
391                self.as_raw_fd(),
392                bufs.as_ptr() as *const libc::iovec,
393                cmp::min(bufs.len(), max_iov()) as libc::c_int,
394                offset as _,
395            )
396        })?;
397        Ok(ret as usize)
398    }
399
400    #[cfg(not(any(
401        target_os = "aix",
402        target_os = "android",
403        target_os = "dragonfly",
404        target_os = "emscripten",
405        target_os = "freebsd",
406        target_os = "fuchsia",
407        target_os = "hurd",
408        target_os = "illumos",
409        target_os = "linux",
410        target_os = "netbsd",
411        target_os = "openbsd",
412        target_vendor = "apple",
413    )))]
414    pub fn write_vectored_at(&self, bufs: &[IoSlice<'_>], offset: u64) -> io::Result<usize> {
415        io::default_write_vectored(|b| self.write_at(b, offset), bufs)
416    }
417
418    // We support some old Android versions that do not have `pwritev` in libc,
419    // so we use weak linkage and fallback to a direct syscall if not available.
420    //
421    // On 32-bit targets, we don't want to deal with weird ABI issues around
422    // passing 64-bits parameters to syscalls, so we fallback to the default
423    // implementation if `pwritev` is not available.
424    #[cfg(all(target_os = "android", target_pointer_width = "64"))]
425    pub fn write_vectored_at(&self, bufs: &[IoSlice<'_>], offset: u64) -> io::Result<usize> {
426        super::weak::syscall! {
427            fn pwritev(
428                fd: libc::c_int,
429                iovec: *const libc::iovec,
430                n_iovec: libc::c_int,
431                offset: off64_t
432            ) -> isize
433        }
434
435        let ret = cvt(unsafe {
436            pwritev(
437                self.as_raw_fd(),
438                bufs.as_ptr() as *const libc::iovec,
439                cmp::min(bufs.len(), max_iov()) as libc::c_int,
440                offset as _,
441            )
442        })?;
443        Ok(ret as usize)
444    }
445
446    #[cfg(all(target_os = "android", target_pointer_width = "32"))]
447    pub fn write_vectored_at(&self, bufs: &[IoSlice<'_>], offset: u64) -> io::Result<usize> {
448        super::weak::weak!(fn pwritev64(libc::c_int, *const libc::iovec, libc::c_int, off64_t) -> isize);
449
450        match pwritev64.get() {
451            Some(pwritev) => {
452                let ret = cvt(unsafe {
453                    pwritev(
454                        self.as_raw_fd(),
455                        bufs.as_ptr() as *const libc::iovec,
456                        cmp::min(bufs.len(), max_iov()) as libc::c_int,
457                        offset as _,
458                    )
459                })?;
460                Ok(ret as usize)
461            }
462            None => io::default_write_vectored(|b| self.write_at(b, offset), bufs),
463        }
464    }
465
466    // We support old MacOS, iOS, watchOS, tvOS and visionOS. `pwritev` was added in the following
467    // Apple OS versions:
468    // ios 14.0
469    // tvos 14.0
470    // macos 11.0
471    // watchos 7.0
472    //
473    // These versions may be newer than the minimum supported versions of OS's we support so we must
474    // use "weak" linking.
475    #[cfg(target_vendor = "apple")]
476    pub fn write_vectored_at(&self, bufs: &[IoSlice<'_>], offset: u64) -> io::Result<usize> {
477        super::weak::weak!(fn pwritev(libc::c_int, *const libc::iovec, libc::c_int, off64_t) -> isize);
478
479        match pwritev.get() {
480            Some(pwritev) => {
481                let ret = cvt(unsafe {
482                    pwritev(
483                        self.as_raw_fd(),
484                        bufs.as_ptr() as *const libc::iovec,
485                        cmp::min(bufs.len(), max_iov()) as libc::c_int,
486                        offset as _,
487                    )
488                })?;
489                Ok(ret as usize)
490            }
491            None => io::default_write_vectored(|b| self.write_at(b, offset), bufs),
492        }
493    }
494
495    #[cfg(not(any(
496        target_env = "newlib",
497        target_os = "solaris",
498        target_os = "illumos",
499        target_os = "emscripten",
500        target_os = "fuchsia",
501        target_os = "l4re",
502        target_os = "linux",
503        target_os = "haiku",
504        target_os = "redox",
505        target_os = "vxworks",
506        target_os = "nto",
507    )))]
508    pub fn set_cloexec(&self) -> io::Result<()> {
509        unsafe {
510            cvt(libc::ioctl(self.as_raw_fd(), libc::FIOCLEX))?;
511            Ok(())
512        }
513    }
514    #[cfg(any(
515        all(
516            target_env = "newlib",
517            not(any(target_os = "espidf", target_os = "horizon", target_os = "vita"))
518        ),
519        target_os = "solaris",
520        target_os = "illumos",
521        target_os = "emscripten",
522        target_os = "fuchsia",
523        target_os = "l4re",
524        target_os = "linux",
525        target_os = "haiku",
526        target_os = "redox",
527        target_os = "vxworks",
528        target_os = "nto",
529    ))]
530    pub fn set_cloexec(&self) -> io::Result<()> {
531        unsafe {
532            let previous = cvt(libc::fcntl(self.as_raw_fd(), libc::F_GETFD))?;
533            let new = previous | libc::FD_CLOEXEC;
534            if new != previous {
535                cvt(libc::fcntl(self.as_raw_fd(), libc::F_SETFD, new))?;
536            }
537            Ok(())
538        }
539    }
540    #[cfg(any(target_os = "espidf", target_os = "horizon", target_os = "vita"))]
541    pub fn set_cloexec(&self) -> io::Result<()> {
542        // FD_CLOEXEC is not supported in ESP-IDF, Horizon OS and Vita but there's no need to,
543        // because none of them supports spawning processes.
544        Ok(())
545    }
546
547    #[cfg(target_os = "linux")]
548    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
549        unsafe {
550            let v = nonblocking as libc::c_int;
551            cvt(libc::ioctl(self.as_raw_fd(), libc::FIONBIO, &v))?;
552            Ok(())
553        }
554    }
555
556    #[cfg(not(target_os = "linux"))]
557    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
558        unsafe {
559            let previous = cvt(libc::fcntl(self.as_raw_fd(), libc::F_GETFL))?;
560            let new = if nonblocking {
561                previous | libc::O_NONBLOCK
562            } else {
563                previous & !libc::O_NONBLOCK
564            };
565            if new != previous {
566                cvt(libc::fcntl(self.as_raw_fd(), libc::F_SETFL, new))?;
567            }
568            Ok(())
569        }
570    }
571
572    #[inline]
573    pub fn duplicate(&self) -> io::Result<FileDesc> {
574        Ok(Self(self.0.try_clone()?))
575    }
576}
577
578impl<'a> Read for &'a FileDesc {
579    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
580        (**self).read(buf)
581    }
582
583    fn read_buf(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
584        (**self).read_buf(cursor)
585    }
586
587    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
588        (**self).read_vectored(bufs)
589    }
590
591    #[inline]
592    fn is_read_vectored(&self) -> bool {
593        (**self).is_read_vectored()
594    }
595}
596
597impl AsInner<OwnedFd> for FileDesc {
598    #[inline]
599    fn as_inner(&self) -> &OwnedFd {
600        &self.0
601    }
602}
603
604impl IntoInner<OwnedFd> for FileDesc {
605    fn into_inner(self) -> OwnedFd {
606        self.0
607    }
608}
609
610impl FromInner<OwnedFd> for FileDesc {
611    fn from_inner(owned_fd: OwnedFd) -> Self {
612        Self(owned_fd)
613    }
614}
615
616impl AsFd for FileDesc {
617    fn as_fd(&self) -> BorrowedFd<'_> {
618        self.0.as_fd()
619    }
620}
621
622impl AsRawFd for FileDesc {
623    #[inline]
624    fn as_raw_fd(&self) -> RawFd {
625        self.0.as_raw_fd()
626    }
627}
628
629impl IntoRawFd for FileDesc {
630    fn into_raw_fd(self) -> RawFd {
631        self.0.into_raw_fd()
632    }
633}
634
635impl FromRawFd for FileDesc {
636    unsafe fn from_raw_fd(raw_fd: RawFd) -> Self {
637        Self(FromRawFd::from_raw_fd(raw_fd))
638    }
639}
std/sys/pal/unix/fd.rs

std/sys/pal/unix/
fd.rs
