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[rustc.git] / src / libstd / sys / unix / fd.rs
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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.
4//
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.
10
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11#![unstable(reason = "not public", issue = "0", feature = "fd")]
12
13use prelude::v1::*;
14
15use io::{self, Read};
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16use libc::{self, c_int, size_t, c_void};
17use mem;
54a0048b 18use sync::atomic::{AtomicBool, Ordering};
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19use sys::cvt;
20use sys_common::AsInner;
54a0048b 21use sys_common::io::read_to_end_uninitialized;
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22
23pub struct FileDesc {
24 fd: c_int,
25}
26
27impl FileDesc {
28 pub fn new(fd: c_int) -> FileDesc {
29 FileDesc { fd: fd }
30 }
31
32 pub fn raw(&self) -> c_int { self.fd }
33
9346a6ac 34 /// Extracts the actual filedescriptor without closing it.
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35 pub fn into_raw(self) -> c_int {
36 let fd = self.fd;
bd371182 37 mem::forget(self);
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38 fd
39 }
40
41 pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
54a0048b 42 let ret = cvt(unsafe {
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43 libc::read(self.fd,
44 buf.as_mut_ptr() as *mut c_void,
45 buf.len() as size_t)
54a0048b 46 })?;
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47 Ok(ret as usize)
48 }
49
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50 pub fn read_to_end(&self, buf: &mut Vec<u8>) -> io::Result<usize> {
51 let mut me = self;
52 (&mut me).read_to_end(buf)
53 }
54
85aaf69f 55 pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
54a0048b 56 let ret = cvt(unsafe {
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57 libc::write(self.fd,
58 buf.as_ptr() as *const c_void,
59 buf.len() as size_t)
54a0048b 60 })?;
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61 Ok(ret as usize)
62 }
9346a6ac 63
7453a54e 64 #[cfg(not(any(target_env = "newlib", target_os = "solaris", target_os = "emscripten")))]
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65 pub fn set_cloexec(&self) {
66 unsafe {
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67 let ret = libc::ioctl(self.fd, libc::FIOCLEX);
68 debug_assert_eq!(ret, 0);
69 }
70 }
7453a54e 71 #[cfg(any(target_env = "newlib", target_os = "solaris", target_os = "emscripten"))]
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72 pub fn set_cloexec(&self) {
73 unsafe {
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74 let previous = libc::fcntl(self.fd, libc::F_GETFD);
75 let ret = libc::fcntl(self.fd, libc::F_SETFD, previous | libc::FD_CLOEXEC);
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76 debug_assert_eq!(ret, 0);
77 }
78 }
7453a54e 79
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80 pub fn set_nonblocking(&self, nonblocking: bool) {
81 unsafe {
82 let previous = libc::fcntl(self.fd, libc::F_GETFL);
83 debug_assert!(previous != -1);
84 let new = if nonblocking {
85 previous | libc::O_NONBLOCK
86 } else {
87 previous & !libc::O_NONBLOCK
88 };
89 let ret = libc::fcntl(self.fd, libc::F_SETFL, new);
90 debug_assert!(ret != -1);
91 }
92 }
93
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94 pub fn duplicate(&self) -> io::Result<FileDesc> {
95 // We want to atomically duplicate this file descriptor and set the
96 // CLOEXEC flag, and currently that's done via F_DUPFD_CLOEXEC. This
97 // flag, however, isn't supported on older Linux kernels (earlier than
98 // 2.6.24).
99 //
100 // To detect this and ensure that CLOEXEC is still set, we
101 // follow a strategy similar to musl [1] where if passing
102 // F_DUPFD_CLOEXEC causes `fcntl` to return EINVAL it means it's not
103 // supported (the third parameter, 0, is always valid), so we stop
104 // trying that.
105 //
106 // Also note that Android doesn't have F_DUPFD_CLOEXEC, but get it to
107 // resolve so we at least compile this.
108 //
109 // [1]: http://comments.gmane.org/gmane.linux.lib.musl.general/2963
110 #[cfg(target_os = "android")]
111 use libc::F_DUPFD as F_DUPFD_CLOEXEC;
112 #[cfg(not(target_os = "android"))]
113 use libc::F_DUPFD_CLOEXEC;
114
115 let make_filedesc = |fd| {
116 let fd = FileDesc::new(fd);
117 fd.set_cloexec();
118 fd
119 };
120 static TRY_CLOEXEC: AtomicBool =
121 AtomicBool::new(!cfg!(target_os = "android"));
122 let fd = self.raw();
123 if TRY_CLOEXEC.load(Ordering::Relaxed) {
124 match cvt(unsafe { libc::fcntl(fd, F_DUPFD_CLOEXEC, 0) }) {
125 // We *still* call the `set_cloexec` method as apparently some
126 // linux kernel at some point stopped setting CLOEXEC even
127 // though it reported doing so on F_DUPFD_CLOEXEC.
128 Ok(fd) => {
129 return Ok(if cfg!(target_os = "linux") {
130 make_filedesc(fd)
131 } else {
132 FileDesc::new(fd)
133 })
134 }
135 Err(ref e) if e.raw_os_error() == Some(libc::EINVAL) => {
136 TRY_CLOEXEC.store(false, Ordering::Relaxed);
137 }
138 Err(e) => return Err(e),
139 }
140 }
141 cvt(unsafe { libc::fcntl(fd, libc::F_DUPFD, 0) }).map(make_filedesc)
142 }
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143}
144
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145impl<'a> Read for &'a FileDesc {
146 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
147 (**self).read(buf)
148 }
149
150 fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
151 unsafe { read_to_end_uninitialized(self, buf) }
152 }
153}
154
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155impl AsInner<c_int> for FileDesc {
156 fn as_inner(&self) -> &c_int { &self.fd }
157}
158
159impl Drop for FileDesc {
160 fn drop(&mut self) {
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161 // Note that errors are ignored when closing a file descriptor. The
162 // reason for this is that if an error occurs we don't actually know if
163 // the file descriptor was closed or not, and if we retried (for
164 // something like EINTR), we might close another valid file descriptor
165 // (opened after we closed ours.
166 let _ = unsafe { libc::close(self.fd) };
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167 }
168}