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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 | ||
54a0048b | 11 | use cmp; |
85aaf69f | 12 | use io; |
7453a54e | 13 | use libc::{self, c_int}; |
54a0048b | 14 | use mem; |
5bcae85e | 15 | use ptr; |
7453a54e SL |
16 | use sys::cvt_r; |
17 | use sys::fd::FileDesc; | |
85aaf69f SL |
18 | |
19 | //////////////////////////////////////////////////////////////////////////////// | |
20 | // Anonymous pipes | |
21 | //////////////////////////////////////////////////////////////////////////////// | |
22 | ||
23 | pub struct AnonPipe(FileDesc); | |
24 | ||
9346a6ac | 25 | pub fn anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> { |
85aaf69f | 26 | let mut fds = [0; 2]; |
7453a54e SL |
27 | |
28 | // Unfortunately the only known way right now to create atomically set the | |
29 | // CLOEXEC flag is to use the `pipe2` syscall on Linux. This was added in | |
30 | // 2.6.27, however, and because we support 2.6.18 we must detect this | |
31 | // support dynamically. | |
32 | if cfg!(target_os = "linux") { | |
33 | weak! { fn pipe2(*mut c_int, c_int) -> c_int } | |
34 | if let Some(pipe) = pipe2.get() { | |
35 | match cvt_r(|| unsafe { pipe(fds.as_mut_ptr(), libc::O_CLOEXEC) }) { | |
36 | Ok(_) => { | |
37 | return Ok((AnonPipe(FileDesc::new(fds[0])), | |
38 | AnonPipe(FileDesc::new(fds[1])))) | |
39 | } | |
40 | Err(ref e) if e.raw_os_error() == Some(libc::ENOSYS) => {} | |
41 | Err(e) => return Err(e), | |
42 | } | |
43 | } | |
44 | } | |
9346a6ac | 45 | if unsafe { libc::pipe(fds.as_mut_ptr()) == 0 } { |
3157f602 XL |
46 | let fd0 = FileDesc::new(fds[0]); |
47 | let fd1 = FileDesc::new(fds[1]); | |
48 | Ok((AnonPipe::from_fd(fd0)?, AnonPipe::from_fd(fd1)?)) | |
85aaf69f SL |
49 | } else { |
50 | Err(io::Error::last_os_error()) | |
51 | } | |
52 | } | |
53 | ||
54 | impl AnonPipe { | |
3157f602 XL |
55 | pub fn from_fd(fd: FileDesc) -> io::Result<AnonPipe> { |
56 | fd.set_cloexec()?; | |
57 | Ok(AnonPipe(fd)) | |
85aaf69f SL |
58 | } |
59 | ||
60 | pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> { | |
61 | self.0.read(buf) | |
62 | } | |
63 | ||
54a0048b SL |
64 | pub fn read_to_end(&self, buf: &mut Vec<u8>) -> io::Result<usize> { |
65 | self.0.read_to_end(buf) | |
66 | } | |
67 | ||
85aaf69f SL |
68 | pub fn write(&self, buf: &[u8]) -> io::Result<usize> { |
69 | self.0.write(buf) | |
70 | } | |
71 | ||
62682a34 | 72 | pub fn fd(&self) -> &FileDesc { &self.0 } |
c1a9b12d | 73 | pub fn into_fd(self) -> FileDesc { self.0 } |
85aaf69f | 74 | } |
54a0048b SL |
75 | |
76 | pub fn read2(p1: AnonPipe, | |
77 | v1: &mut Vec<u8>, | |
78 | p2: AnonPipe, | |
79 | v2: &mut Vec<u8>) -> io::Result<()> { | |
80 | // Set both pipes into nonblocking mode as we're gonna be reading from both | |
81 | // in the `select` loop below, and we wouldn't want one to block the other! | |
82 | let p1 = p1.into_fd(); | |
83 | let p2 = p2.into_fd(); | |
3157f602 XL |
84 | p1.set_nonblocking(true)?; |
85 | p2.set_nonblocking(true)?; | |
54a0048b SL |
86 | |
87 | let max = cmp::max(p1.raw(), p2.raw()); | |
88 | loop { | |
89 | // wait for either pipe to become readable using `select` | |
90 | cvt_r(|| unsafe { | |
91 | let mut read: libc::fd_set = mem::zeroed(); | |
92 | libc::FD_SET(p1.raw(), &mut read); | |
93 | libc::FD_SET(p2.raw(), &mut read); | |
5bcae85e SL |
94 | libc::select(max + 1, &mut read, ptr::null_mut(), ptr::null_mut(), |
95 | ptr::null_mut()) | |
54a0048b SL |
96 | })?; |
97 | ||
98 | // Read as much as we can from each pipe, ignoring EWOULDBLOCK or | |
99 | // EAGAIN. If we hit EOF, then this will happen because the underlying | |
100 | // reader will return Ok(0), in which case we'll see `Ok` ourselves. In | |
101 | // this case we flip the other fd back into blocking mode and read | |
102 | // whatever's leftover on that file descriptor. | |
103 | let read = |fd: &FileDesc, dst: &mut Vec<u8>| { | |
104 | match fd.read_to_end(dst) { | |
105 | Ok(_) => Ok(true), | |
106 | Err(e) => { | |
107 | if e.raw_os_error() == Some(libc::EWOULDBLOCK) || | |
108 | e.raw_os_error() == Some(libc::EAGAIN) { | |
109 | Ok(false) | |
110 | } else { | |
111 | Err(e) | |
112 | } | |
113 | } | |
114 | } | |
115 | }; | |
116 | if read(&p1, v1)? { | |
3157f602 | 117 | p2.set_nonblocking(false)?; |
54a0048b SL |
118 | return p2.read_to_end(v2).map(|_| ()); |
119 | } | |
120 | if read(&p2, v2)? { | |
3157f602 | 121 | p1.set_nonblocking(false)?; |
54a0048b SL |
122 | return p1.read_to_end(v1).map(|_| ()); |
123 | } | |
124 | } | |
125 | } |