1 //! The libc backend.
2 //!
3 //! On most platforms, this uses the `libc` crate to make system calls. On
4 //! Windows, this uses the Winsock API in `windows-sys`, which can be adapted
5 //! to have a very `libc`-like interface.
6
7 // Every FFI call requires an unsafe block, and there are a lot of FFI
8 // calls. For now, set this to allow for the libc backend.
9 #![allow(clippy::undocumented_unsafe_blocks)]
10 // Lots of libc types vary between platforms, so we often need a `.into()` on
11 // one platform where it's redundant on another.
12 #![allow(clippy::useless_conversion)]
13
14 mod conv;
15
16 #[cfg(windows)]
17 pub(crate) mod fd {
18 pub use crate::maybe_polyfill::os::windows::io::{
19 AsRawSocket, AsSocket, BorrowedSocket as BorrowedFd, FromRawSocket, IntoRawSocket,
20 OwnedSocket as OwnedFd, RawSocket as RawFd,
21 };
22 pub(crate) use windows_sys::Win32::Networking::WinSock::SOCKET as LibcFd;
23
24 /// A version of [`AsRawFd`] for use with Winsock API.
25 ///
26 /// [`AsRawFd`]: https://doc.rust-lang.org/stable/std/os/fd/trait.AsRawFd.html
27 pub trait AsRawFd {
28 /// A version of [`as_raw_fd`] for use with Winsock API.
29 ///
30 /// [`as_raw_fd`]: https://doc.rust-lang.org/stable/std/os/fd/trait.FromRawFd.html#tymethod.as_raw_fd
as_raw_fd(&self) -> RawFd31 fn as_raw_fd(&self) -> RawFd;
32 }
33 impl<T: AsRawSocket> AsRawFd for T {
34 #[inline]
as_raw_fd(&self) -> RawFd35 fn as_raw_fd(&self) -> RawFd {
36 self.as_raw_socket()
37 }
38 }
39
40 /// A version of [`IntoRawFd`] for use with Winsock API.
41 ///
42 /// [`IntoRawFd`]: https://doc.rust-lang.org/stable/std/os/fd/trait.IntoRawFd.html
43 pub trait IntoRawFd {
44 /// A version of [`into_raw_fd`] for use with Winsock API.
45 ///
46 /// [`into_raw_fd`]: https://doc.rust-lang.org/stable/std/os/fd/trait.FromRawFd.html#tymethod.into_raw_fd
into_raw_fd(self) -> RawFd47 fn into_raw_fd(self) -> RawFd;
48 }
49 impl<T: IntoRawSocket> IntoRawFd for T {
50 #[inline]
into_raw_fd(self) -> RawFd51 fn into_raw_fd(self) -> RawFd {
52 self.into_raw_socket()
53 }
54 }
55
56 /// A version of [`FromRawFd`] for use with Winsock API.
57 ///
58 /// [`FromRawFd`]: https://doc.rust-lang.org/stable/std/os/fd/trait.FromRawFd.html
59 pub trait FromRawFd {
60 /// A version of [`from_raw_fd`] for use with Winsock API.
61 ///
62 /// # Safety
63 ///
64 /// See the [safety requirements] for [`from_raw_fd`].
65 ///
66 /// [`from_raw_fd`]: https://doc.rust-lang.org/stable/std/os/fd/trait.FromRawFd.html#tymethod.from_raw_fd
67 /// [safety requirements]: https://doc.rust-lang.org/stable/std/os/fd/trait.FromRawFd.html#safety
from_raw_fd(raw_fd: RawFd) -> Self68 unsafe fn from_raw_fd(raw_fd: RawFd) -> Self;
69 }
70 impl<T: FromRawSocket> FromRawFd for T {
71 #[inline]
from_raw_fd(raw_fd: RawFd) -> Self72 unsafe fn from_raw_fd(raw_fd: RawFd) -> Self {
73 Self::from_raw_socket(raw_fd)
74 }
75 }
76
77 /// A version of [`AsFd`] for use with Winsock API.
78 ///
79 /// [`AsFd`]: https://doc.rust-lang.org/stable/std/os/fd/trait.AsFd.html
80 pub trait AsFd {
81 /// An `as_fd` function for Winsock, where a `Fd` is a `Socket`.
as_fd(&self) -> BorrowedFd82 fn as_fd(&self) -> BorrowedFd;
83 }
84 impl<T: AsSocket> AsFd for T {
85 #[inline]
as_fd(&self) -> BorrowedFd86 fn as_fd(&self) -> BorrowedFd {
87 self.as_socket()
88 }
89 }
90 }
91 #[cfg(not(windows))]
92 pub(crate) mod fd {
93 pub use crate::maybe_polyfill::os::fd::{
94 AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd,
95 };
96 #[allow(unused_imports)]
97 pub(crate) use RawFd as LibcFd;
98 }
99
100 // On Windows we emulate selected libc-compatible interfaces. On non-Windows,
101 // we just use libc here, since this is the libc backend.
102 #[cfg_attr(windows, path = "winsock_c.rs")]
103 pub(crate) mod c;
104
105 #[cfg(feature = "event")]
106 pub(crate) mod event;
107 #[cfg(not(windows))]
108 #[cfg(feature = "fs")]
109 pub(crate) mod fs;
110 pub(crate) mod io;
111 #[cfg(linux_kernel)]
112 #[cfg(feature = "io_uring")]
113 pub(crate) mod io_uring;
114 #[cfg(not(any(windows, target_os = "espidf", target_os = "vita", target_os = "wasi")))]
115 #[cfg(feature = "mm")]
116 pub(crate) mod mm;
117 #[cfg(linux_kernel)]
118 #[cfg(feature = "mount")]
119 pub(crate) mod mount;
120 #[cfg(linux_kernel)]
121 #[cfg(all(feature = "fs", not(feature = "mount")))]
122 pub(crate) mod mount; // for deprecated mount functions in "fs"
123 #[cfg(not(any(target_os = "redox", target_os = "wasi")))]
124 #[cfg(feature = "net")]
125 pub(crate) mod net;
126 #[cfg(not(any(windows, target_os = "espidf")))]
127 #[cfg(any(
128 feature = "param",
129 feature = "runtime",
130 feature = "time",
131 target_arch = "x86",
132 ))]
133 pub(crate) mod param;
134 #[cfg(not(windows))]
135 #[cfg(feature = "pipe")]
136 pub(crate) mod pipe;
137 #[cfg(not(windows))]
138 #[cfg(feature = "process")]
139 pub(crate) mod process;
140 #[cfg(not(windows))]
141 #[cfg(not(target_os = "wasi"))]
142 #[cfg(feature = "pty")]
143 pub(crate) mod pty;
144 #[cfg(not(windows))]
145 #[cfg(feature = "rand")]
146 pub(crate) mod rand;
147 #[cfg(not(windows))]
148 #[cfg(not(target_os = "wasi"))]
149 #[cfg(feature = "system")]
150 pub(crate) mod system;
151 #[cfg(not(any(windows, target_os = "vita")))]
152 #[cfg(feature = "termios")]
153 pub(crate) mod termios;
154 #[cfg(not(windows))]
155 #[cfg(feature = "thread")]
156 pub(crate) mod thread;
157 #[cfg(not(any(windows, target_os = "espidf")))]
158 #[cfg(feature = "time")]
159 pub(crate) mod time;
160
161 /// If the host libc is glibc, return `true` if it is less than version 2.25.
162 ///
163 /// To restate and clarify, this function returning true does not mean the libc
164 /// is glibc just that if it is glibc, it is less than version 2.25.
165 ///
166 /// For now, this function is only available on Linux, but if it ends up being
167 /// used beyond that, this could be changed to e.g. `#[cfg(unix)]`.
168 #[cfg(all(unix, target_env = "gnu"))]
if_glibc_is_less_than_2_25() -> bool169 pub(crate) fn if_glibc_is_less_than_2_25() -> bool {
170 // This is also defined inside `weak_or_syscall!` in
171 // backend/libc/rand/syscalls.rs, but it's not convenient to re-export the
172 // weak symbol from that macro, so we duplicate it at a small cost here.
173 weak! { fn getrandom(*mut c::c_void, c::size_t, c::c_uint) -> c::ssize_t }
174
175 // glibc 2.25 has `getrandom`, which is how we satisfy the API contract of
176 // this function. But, there are likely other libc versions which have it.
177 getrandom.get().is_none()
178 }
179
180 // Private modules used by multiple public modules.
181 #[cfg(any(feature = "procfs", feature = "process", feature = "runtime"))]
182 #[cfg(not(any(windows, target_os = "wasi")))]
183 pub(crate) mod pid;
184 #[cfg(any(feature = "process", feature = "thread"))]
185 #[cfg(linux_kernel)]
186 pub(crate) mod prctl;
187 #[cfg(not(any(
188 windows,
189 target_os = "android",
190 target_os = "espidf",
191 target_os = "vita",
192 target_os = "wasi"
193 )))]
194 #[cfg(feature = "shm")]
195 pub(crate) mod shm;
196 #[cfg(any(feature = "fs", feature = "thread", feature = "process"))]
197 #[cfg(not(any(windows, target_os = "wasi")))]
198 pub(crate) mod ugid;
199
200 #[cfg(bsd)]
201 const MAX_IOV: usize = c::IOV_MAX as usize;
202
203 #[cfg(any(linux_kernel, target_os = "emscripten", target_os = "nto"))]
204 const MAX_IOV: usize = c::UIO_MAXIOV as usize;
205
206 #[cfg(not(any(
207 bsd,
208 linux_kernel,
209 windows,
210 target_os = "emscripten",
211 target_os = "espidf",
212 target_os = "nto",
213 target_os = "horizon",
214 )))]
215 const MAX_IOV: usize = 16; // The minimum value required by POSIX.
216