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