fork 0.10.0

Library for creating a new process detached from the controlling terminal (daemon)
Documentation 
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//! Small platform-specific primitives used only on reviewed post-fork paths.

use std::os::fd::RawFd;

pub(crate) fn write_all(descriptor: RawFd, bytes: &[u8]) -> Result<(), libc::c_int> {
    let mut written = 0;
    while written < bytes.len() {
        let Some(remaining) = bytes.get(written..) else {
            return Err(libc::EIO);
        };
        // SAFETY: descriptor is live and remaining points to initialized bytes.
        let result = unsafe { libc::write(descriptor, remaining.as_ptr().cast(), remaining.len()) };
        if result > 0 {
            written += result.unsigned_abs();
        } else if result != -1 {
            return Err(libc::EIO);
        } else {
            let errno = last_errno();
            if errno != libc::EINTR {
                return Err(errno);
            }
        }
    }
    Ok(())
}

#[cfg(any(target_os = "linux", target_os = "dragonfly"))]
pub(crate) fn last_errno() -> libc::c_int {
    // SAFETY: libc returns a thread-local errno pointer for the current thread.
    unsafe { *libc::__errno_location() }
}

#[cfg(target_os = "android")]
pub(crate) fn last_errno() -> libc::c_int {
    // SAFETY: libc returns a thread-local errno pointer for the current thread.
    unsafe { *libc::__errno() }
}

#[cfg(any(target_os = "netbsd", target_os = "openbsd"))]
pub(crate) fn last_errno() -> libc::c_int {
    // SAFETY: libc returns a thread-local errno pointer for the current thread.
    unsafe { *libc::__errno() }
}

#[cfg(any(target_os = "freebsd", target_vendor = "apple"))]
pub(crate) fn last_errno() -> libc::c_int {
    // SAFETY: libc returns a thread-local errno pointer for the current thread.
    unsafe { *libc::__error() }
}

#[cfg(all(
    not(any(
        target_os = "linux",
        target_os = "dragonfly",
        target_os = "android",
        target_os = "netbsd",
        target_os = "openbsd"
    )),
    not(any(target_os = "freebsd", target_vendor = "apple"))
))]
pub(crate) fn last_errno() -> libc::c_int {
    std::io::Error::last_os_error()
        .raw_os_error()
        .unwrap_or(libc::EIO)
}