1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 #![unstable(reason = "not public", issue = "0", feature = "fd")]
15 use libc::{self, c_int, c_void, ssize_t};
17 use sync::atomic::{AtomicBool, Ordering};
19 use sys_common::AsInner;
26 fn max_len() -> usize {
27 // The maximum read limit on most posix-like systems is `SSIZE_MAX`,
28 // with the man page quoting that if the count of bytes to read is
29 // greater than `SSIZE_MAX` the result is "unspecified".
31 // On macOS, however, apparently the 64-bit libc is either buggy or
32 // intentionally showing odd behavior by rejecting any read with a size
33 // larger than or equal to INT_MAX. To handle both of these the read
34 // size is capped on both platforms.
35 if cfg!(target_os = "macos") {
36 <c_int>::max_value() as usize - 1
38 <ssize_t>::max_value() as usize
43 pub fn new(fd: c_int) -> FileDesc {
47 pub fn raw(&self) -> c_int { self.fd }
49 /// Extracts the actual filedescriptor without closing it.
50 pub fn into_raw(self) -> c_int {
56 pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
57 let ret = cvt(unsafe {
59 buf.as_mut_ptr() as *mut c_void,
60 cmp::min(buf.len(), max_len()))
65 pub fn read_to_end(&self, buf: &mut Vec<u8>) -> io::Result<usize> {
67 (&mut me).read_to_end(buf)
70 pub fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
71 #[cfg(target_os = "android")]
72 use super::android::cvt_pread64;
74 #[cfg(target_os = "emscripten")]
75 unsafe fn cvt_pread64(fd: c_int, buf: *mut c_void, count: usize, offset: i64)
79 cvt(pread64(fd, buf, count, offset as i32))
82 #[cfg(not(any(target_os = "android", target_os = "emscripten")))]
83 unsafe fn cvt_pread64(fd: c_int, buf: *mut c_void, count: usize, offset: i64)
86 #[cfg(target_os = "linux")]
88 #[cfg(not(target_os = "linux"))]
89 use libc::pread as pread64;
90 cvt(pread64(fd, buf, count, offset))
95 buf.as_mut_ptr() as *mut c_void,
96 cmp::min(buf.len(), max_len()),
102 pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
103 let ret = cvt(unsafe {
105 buf.as_ptr() as *const c_void,
106 cmp::min(buf.len(), max_len()))
111 pub fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
112 #[cfg(target_os = "android")]
113 use super::android::cvt_pwrite64;
115 #[cfg(target_os = "emscripten")]
116 unsafe fn cvt_pwrite64(fd: c_int, buf: *const c_void, count: usize, offset: i64)
120 cvt(pwrite64(fd, buf, count, offset as i32))
123 #[cfg(not(any(target_os = "android", target_os = "emscripten")))]
124 unsafe fn cvt_pwrite64(fd: c_int, buf: *const c_void, count: usize, offset: i64)
127 #[cfg(target_os = "linux")]
129 #[cfg(not(target_os = "linux"))]
130 use libc::pwrite as pwrite64;
131 cvt(pwrite64(fd, buf, count, offset))
135 cvt_pwrite64(self.fd,
136 buf.as_ptr() as *const c_void,
137 cmp::min(buf.len(), max_len()),
143 #[cfg(not(any(target_env = "newlib",
144 target_os = "solaris",
145 target_os = "emscripten",
146 target_os = "fuchsia",
147 target_os = "haiku")))]
148 pub fn set_cloexec(&self) -> io::Result<()> {
150 cvt(libc::ioctl(self.fd, libc::FIOCLEX))?;
154 #[cfg(any(target_env = "newlib",
155 target_os = "solaris",
156 target_os = "emscripten",
157 target_os = "fuchsia",
158 target_os = "haiku"))]
159 pub fn set_cloexec(&self) -> io::Result<()> {
161 let previous = cvt(libc::fcntl(self.fd, libc::F_GETFD))?;
162 let new = previous | libc::FD_CLOEXEC;
164 cvt(libc::fcntl(self.fd, libc::F_SETFD, new))?;
170 #[cfg(target_os = "linux")]
171 pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
173 let v = nonblocking as c_int;
174 cvt(libc::ioctl(self.fd, libc::FIONBIO, &v))?;
179 #[cfg(not(target_os = "linux"))]
180 pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
182 let previous = cvt(libc::fcntl(self.fd, libc::F_GETFL))?;
183 let new = if nonblocking {
184 previous | libc::O_NONBLOCK
186 previous & !libc::O_NONBLOCK
189 cvt(libc::fcntl(self.fd, libc::F_SETFL, new))?;
195 pub fn duplicate(&self) -> io::Result<FileDesc> {
196 // We want to atomically duplicate this file descriptor and set the
197 // CLOEXEC flag, and currently that's done via F_DUPFD_CLOEXEC. This
198 // flag, however, isn't supported on older Linux kernels (earlier than
201 // To detect this and ensure that CLOEXEC is still set, we
202 // follow a strategy similar to musl [1] where if passing
203 // F_DUPFD_CLOEXEC causes `fcntl` to return EINVAL it means it's not
204 // supported (the third parameter, 0, is always valid), so we stop
207 // Also note that Android doesn't have F_DUPFD_CLOEXEC, but get it to
208 // resolve so we at least compile this.
210 // [1]: http://comments.gmane.org/gmane.linux.lib.musl.general/2963
211 #[cfg(any(target_os = "android", target_os = "haiku"))]
212 use libc::F_DUPFD as F_DUPFD_CLOEXEC;
213 #[cfg(not(any(target_os = "android", target_os="haiku")))]
214 use libc::F_DUPFD_CLOEXEC;
216 let make_filedesc = |fd| {
217 let fd = FileDesc::new(fd);
221 static TRY_CLOEXEC: AtomicBool =
222 AtomicBool::new(!cfg!(target_os = "android"));
224 if TRY_CLOEXEC.load(Ordering::Relaxed) {
225 match cvt(unsafe { libc::fcntl(fd, F_DUPFD_CLOEXEC, 0) }) {
226 // We *still* call the `set_cloexec` method as apparently some
227 // linux kernel at some point stopped setting CLOEXEC even
228 // though it reported doing so on F_DUPFD_CLOEXEC.
230 return Ok(if cfg!(target_os = "linux") {
236 Err(ref e) if e.raw_os_error() == Some(libc::EINVAL) => {
237 TRY_CLOEXEC.store(false, Ordering::Relaxed);
239 Err(e) => return Err(e),
242 cvt(unsafe { libc::fcntl(fd, libc::F_DUPFD, 0) }).and_then(make_filedesc)
246 impl<'a> Read for &'a FileDesc {
247 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
252 impl AsInner<c_int> for FileDesc {
253 fn as_inner(&self) -> &c_int { &self.fd }
256 impl Drop for FileDesc {
258 // Note that errors are ignored when closing a file descriptor. The
259 // reason for this is that if an error occurs we don't actually know if
260 // the file descriptor was closed or not, and if we retried (for
261 // something like EINTR), we might close another valid file descriptor
262 // (opened after we closed ours.
263 let _ = unsafe { libc::close(self.fd) };