| // 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. |
| use crate::error::ERRNO_NOT_POSITIVE; |
| use crate::util::LazyUsize; |
| use crate::Error; |
| use core::num::NonZeroU32; |
| use core::ptr::NonNull; |
| |
| cfg_if! { |
| if #[cfg(any(target_os = "netbsd", target_os = "openbsd", target_os = "android"))] { |
| use libc::__errno as errno_location; |
| } else if #[cfg(any(target_os = "linux", target_os = "emscripten", target_os = "redox"))] { |
| use libc::__errno_location as errno_location; |
| } else if #[cfg(any(target_os = "solaris", target_os = "illumos"))] { |
| use libc::___errno as errno_location; |
| } else if #[cfg(any(target_os = "macos", target_os = "freebsd", target_os = "dragonfly"))] { |
| use libc::__error as errno_location; |
| } else if #[cfg(target_os = "haiku")] { |
| use libc::_errnop as errno_location; |
| } |
| } |
| |
| pub fn last_os_error() -> Error { |
| #[cfg(not(target_os = "vxworks"))] |
| let errno = unsafe { *errno_location() }; |
| #[cfg(target_os = "vxworks")] |
| let errno = unsafe { libc::errnoGet() }; |
| if errno > 0 { |
| Error::from(NonZeroU32::new(errno as u32).unwrap()) |
| } else { |
| ERRNO_NOT_POSITIVE |
| } |
| } |
| |
| // 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 |
| pub fn sys_fill_exact( |
| mut buf: &mut [u8], |
| sys_fill: impl Fn(&mut [u8]) -> libc::ssize_t, |
| ) -> Result<(), Error> { |
| while !buf.is_empty() { |
| let res = sys_fill(buf); |
| if res < 0 { |
| let err = last_os_error(); |
| // We should try again if the call was interrupted. |
| if err.raw_os_error() != Some(libc::EINTR) { |
| return Err(err); |
| } |
| } else { |
| // We don't check for EOF (ret = 0) as the data we are reading |
| // should be an infinite stream of random bytes. |
| buf = &mut buf[(res as usize)..]; |
| } |
| } |
| Ok(()) |
| } |
| |
| // 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. |
| // F must be a function pointer of type `unsafe extern "C" fn`. Based off of the |
| // weak! macro in libstd. |
| pub struct Weak { |
| name: &'static str, |
| addr: LazyUsize, |
| } |
| |
| impl Weak { |
| // Construct a binding to a C function with a given name. This function is |
| // unsafe because `name` _must_ be null terminated. |
| pub const unsafe fn new(name: &'static str) -> Self { |
| Self { |
| name, |
| addr: LazyUsize::new(), |
| } |
| } |
| |
| // Return a function pointer if present at runtime. Otherwise, return null. |
| pub fn ptr(&self) -> Option<NonNull<libc::c_void>> { |
| let addr = self.addr.unsync_init(|| unsafe { |
| libc::dlsym(libc::RTLD_DEFAULT, self.name.as_ptr() as *const _) as usize |
| }); |
| NonNull::new(addr as *mut _) |
| } |
| } |
| |
| pub struct LazyFd(LazyUsize); |
| |
| impl LazyFd { |
| pub const fn new() -> Self { |
| Self(LazyUsize::new()) |
| } |
| |
| // If init() returns Some(x), x should be nonnegative. |
| pub fn init(&self, init: impl FnOnce() -> Option<libc::c_int>) -> Option<libc::c_int> { |
| let fd = self.0.sync_init( |
| || match init() { |
| // OK as val >= 0 and val <= c_int::MAX < usize::MAX |
| Some(val) => val as usize, |
| None => LazyUsize::UNINIT, |
| }, |
| || unsafe { |
| // We are usually waiting on an open(2) syscall to complete, |
| // which typically takes < 10us if the file is a device. |
| // However, we might end up waiting much longer if the entropy |
| // pool isn't initialized, but even in that case, this loop will |
| // consume a negligible amount of CPU on most platforms. |
| libc::usleep(10); |
| }, |
| ); |
| match fd { |
| LazyUsize::UNINIT => None, |
| val => Some(val as libc::c_int), |
| } |
| } |
| } |
| |
| cfg_if! { |
| if #[cfg(any(target_os = "linux", target_os = "emscripten"))] { |
| use libc::open64 as open; |
| } else { |
| use libc::open; |
| } |
| } |
| |
| // SAFETY: path must be null terminated, FD must be manually closed. |
| pub unsafe fn open_readonly(path: &str) -> Option<libc::c_int> { |
| debug_assert!(path.as_bytes().last() == Some(&0)); |
| let fd = open(path.as_ptr() as *mut _, libc::O_RDONLY | libc::O_CLOEXEC); |
| if fd < 0 { |
| return None; |
| } |
| // O_CLOEXEC works on all Unix targets except for older Linux kernels (pre |
| // 2.6.23), so we also use an ioctl to make sure FD_CLOEXEC is set. |
| #[cfg(target_os = "linux")] |
| libc::ioctl(fd, libc::FIOCLEX); |
| Some(fd) |
| } |