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| </pre><pre class="rust"><code><span class="comment">// Copyright 2019 Developers of the Rand project. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // https://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| </span><span class="attribute">#![allow(dead_code)] |
| </span><span class="kw">use </span><span class="kw">crate</span>::Error; |
| <span class="kw">use </span>core::{ |
| cmp::min, |
| mem::MaybeUninit, |
| num::NonZeroU32, |
| ptr::NonNull, |
| sync::atomic::{fence, AtomicPtr, Ordering}, |
| }; |
| <span class="kw">use </span>libc::c_void; |
| |
| <span class="macro">cfg_if! </span>{ |
| <span class="kw">if </span><span class="attribute">#[cfg(any(target_os = <span class="string">"netbsd"</span>, target_os = <span class="string">"openbsd"</span>, target_os = <span class="string">"android"</span>))] </span>{ |
| <span class="kw">use </span>libc::__errno <span class="kw">as </span>errno_location; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(any(target_os = <span class="string">"linux"</span>, target_os = <span class="string">"emscripten"</span>, target_os = <span class="string">"redox"</span>))] </span>{ |
| <span class="kw">use </span>libc::__errno_location <span class="kw">as </span>errno_location; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(any(target_os = <span class="string">"solaris"</span>, target_os = <span class="string">"illumos"</span>))] </span>{ |
| <span class="kw">use </span>libc::___errno <span class="kw">as </span>errno_location; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(any(target_os = <span class="string">"macos"</span>, target_os = <span class="string">"freebsd"</span>))] </span>{ |
| <span class="kw">use </span>libc::__error <span class="kw">as </span>errno_location; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(target_os = <span class="string">"haiku"</span>)] </span>{ |
| <span class="kw">use </span>libc::_errnop <span class="kw">as </span>errno_location; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(target_os = <span class="string">"nto"</span>)] </span>{ |
| <span class="kw">use </span>libc::__get_errno_ptr <span class="kw">as </span>errno_location; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(all(target_os = <span class="string">"horizon"</span>, target_arch = <span class="string">"arm"</span>))] </span>{ |
| <span class="kw">extern </span><span class="string">"C" </span>{ |
| <span class="comment">// Not provided by libc: https://github.com/rust-lang/libc/issues/1995 |
| </span><span class="kw">fn </span>__errno() -> <span class="kw-2">*mut </span>libc::c_int; |
| } |
| <span class="kw">use </span>__errno <span class="kw">as </span>errno_location; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(target_os = <span class="string">"aix"</span>)] </span>{ |
| <span class="kw">use </span>libc::_Errno <span class="kw">as </span>errno_location; |
| } |
| } |
| |
| <span class="macro">cfg_if! </span>{ |
| <span class="kw">if </span><span class="attribute">#[cfg(target_os = <span class="string">"vxworks"</span>)] </span>{ |
| <span class="kw">use </span>libc::errnoGet <span class="kw">as </span>get_errno; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(target_os = <span class="string">"dragonfly"</span>)] </span>{ |
| <span class="comment">// Until rust-lang/rust#29594 is stable, we cannot get the errno value |
| // on DragonFlyBSD. So we just return an out-of-range errno. |
| </span><span class="kw">unsafe fn </span>get_errno() -> libc::c_int { -<span class="number">1 </span>} |
| } <span class="kw">else </span>{ |
| <span class="kw">unsafe fn </span>get_errno() -> libc::c_int { <span class="kw-2">*</span>errno_location() } |
| } |
| } |
| |
| <span class="kw">pub fn </span>last_os_error() -> Error { |
| <span class="kw">let </span>errno = <span class="kw">unsafe </span>{ get_errno() }; |
| <span class="kw">if </span>errno > <span class="number">0 </span>{ |
| Error::from(NonZeroU32::new(errno <span class="kw">as </span>u32).unwrap()) |
| } <span class="kw">else </span>{ |
| Error::ERRNO_NOT_POSITIVE |
| } |
| } |
| |
| <span class="comment">// Fill a buffer by repeatedly invoking a system call. The `sys_fill` function: |
| // - should return -1 and set errno on failure |
| // - should return the number of bytes written on success |
| </span><span class="kw">pub fn </span>sys_fill_exact( |
| <span class="kw-2">mut </span>buf: <span class="kw-2">&mut </span>[MaybeUninit<u8>], |
| sys_fill: <span class="kw">impl </span>Fn(<span class="kw-2">&mut </span>[MaybeUninit<u8>]) -> libc::ssize_t, |
| ) -> <span class="prelude-ty">Result</span><(), Error> { |
| <span class="kw">while </span>!buf.is_empty() { |
| <span class="kw">let </span>res = sys_fill(buf); |
| <span class="kw">if </span>res < <span class="number">0 </span>{ |
| <span class="kw">let </span>err = last_os_error(); |
| <span class="comment">// We should try again if the call was interrupted. |
| </span><span class="kw">if </span>err.raw_os_error() != <span class="prelude-val">Some</span>(libc::EINTR) { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(err); |
| } |
| } <span class="kw">else </span>{ |
| <span class="comment">// We don't check for EOF (ret = 0) as the data we are reading |
| // should be an infinite stream of random bytes. |
| </span><span class="kw">let </span>len = min(res <span class="kw">as </span>usize, buf.len()); |
| buf = <span class="kw-2">&mut </span>buf[len..]; |
| } |
| } |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="comment">// A "weak" binding to a C function that may or may not be present at runtime. |
| // Used for supporting newer OS features while still building on older systems. |
| // Based off of the DlsymWeak struct in libstd: |
| // https://github.com/rust-lang/rust/blob/1.61.0/library/std/src/sys/unix/weak.rs#L84 |
| // except that the caller must manually cast self.ptr() to a function pointer. |
| </span><span class="kw">pub struct </span>Weak { |
| name: <span class="kw-2">&</span><span class="lifetime">'static </span>str, |
| addr: AtomicPtr<c_void>, |
| } |
| |
| <span class="kw">impl </span>Weak { |
| <span class="comment">// A non-null pointer value which indicates we are uninitialized. This |
| // constant should ideally not be a valid address of a function pointer. |
| // However, if by chance libc::dlsym does return UNINIT, there will not |
| // be undefined behavior. libc::dlsym will just be called each time ptr() |
| // is called. This would be inefficient, but correct. |
| // TODO: Replace with core::ptr::invalid_mut(1) when that is stable. |
| </span><span class="kw">const </span>UNINIT: <span class="kw-2">*mut </span>c_void = <span class="number">1 </span><span class="kw">as </span><span class="kw-2">*mut </span>c_void; |
| |
| <span class="comment">// Construct a binding to a C function with a given name. This function is |
| // unsafe because `name` _must_ be null terminated. |
| </span><span class="kw">pub const unsafe fn </span>new(name: <span class="kw-2">&</span><span class="lifetime">'static </span>str) -> <span class="self">Self </span>{ |
| <span class="self">Self </span>{ |
| name, |
| addr: AtomicPtr::new(<span class="self">Self</span>::UNINIT), |
| } |
| } |
| |
| <span class="comment">// Return the address of a function if present at runtime. Otherwise, |
| // return None. Multiple callers can call ptr() concurrently. It will |
| // always return _some_ value returned by libc::dlsym. However, the |
| // dlsym function may be called multiple times. |
| </span><span class="kw">pub fn </span>ptr(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><NonNull<c_void>> { |
| <span class="comment">// Despite having only a single atomic variable (self.addr), we still |
| // cannot always use Ordering::Relaxed, as we need to make sure a |
| // successful call to dlsym() is "ordered before" any data read through |
| // the returned pointer (which occurs when the function is called). |
| // Our implementation mirrors that of the one in libstd, meaning that |
| // the use of non-Relaxed operations is probably unnecessary. |
| </span><span class="kw">match </span><span class="self">self</span>.addr.load(Ordering::Relaxed) { |
| <span class="self">Self</span>::UNINIT => { |
| <span class="kw">let </span>symbol = <span class="self">self</span>.name.as_ptr() <span class="kw">as </span><span class="kw-2">*const </span><span class="kw">_</span>; |
| <span class="kw">let </span>addr = <span class="kw">unsafe </span>{ libc::dlsym(libc::RTLD_DEFAULT, symbol) }; |
| <span class="comment">// Synchronizes with the Acquire fence below |
| </span><span class="self">self</span>.addr.store(addr, Ordering::Release); |
| NonNull::new(addr) |
| } |
| addr => { |
| <span class="kw">let </span>func = NonNull::new(addr)<span class="question-mark">?</span>; |
| fence(Ordering::Acquire); |
| <span class="prelude-val">Some</span>(func) |
| } |
| } |
| } |
| } |
| |
| <span class="comment">// SAFETY: path must be null terminated, FD must be manually closed. |
| </span><span class="kw">pub unsafe fn </span>open_readonly(path: <span class="kw-2">&</span>str) -> <span class="prelude-ty">Result</span><libc::c_int, Error> { |
| <span class="macro">debug_assert_eq!</span>(path.as_bytes().last(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">0</span>)); |
| <span class="kw">loop </span>{ |
| <span class="kw">let </span>fd = libc::open(path.as_ptr() <span class="kw">as </span><span class="kw-2">*const </span><span class="kw">_</span>, libc::O_RDONLY | libc::O_CLOEXEC); |
| <span class="kw">if </span>fd >= <span class="number">0 </span>{ |
| <span class="kw">return </span><span class="prelude-val">Ok</span>(fd); |
| } |
| <span class="kw">let </span>err = last_os_error(); |
| <span class="comment">// We should try again if open() was interrupted. |
| </span><span class="kw">if </span>err.raw_os_error() != <span class="prelude-val">Some</span>(libc::EINTR) { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(err); |
| } |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="getrandom" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
