view rust/chg/src/procutil.rs @ 48598:a6f16ec07ed7

stream-clone: add a explicit test for format change during stream clone

They are different kind of requirements, the one which impact the data storage
and are relevant to the files being streamed and the one which does not. For
example some requirements are only relevant to the working copy, like sparse, or
dirstate-v2.

Since they are irrelevant to the content being streamed, they do not prevent the
receiving side to use streaming clone and mercurial skip adverting them over
the wire and, ideally, within the bundle.

In addition, this let the client decide to use whichever format it desire for
the part that does not affect the store itself. So the configuration related to
these format are used as normal when doing a streaming clone.

In practice, the feature was not really tested and is badly broken with bundle-2,
since the requirements are not filtered out from the stream bundle.

So we start with adding simple tests as a good base before the fix and adjust
the feature.

Differential Revision: https://phab.mercurial-scm.org/D12029

// Copyright 2018 Yuya Nishihara <[e-mail]>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

//! Low-level utility for signal and process handling.

use libc::{self, c_int, pid_t, size_t, ssize_t};
use std::io;
use std::os::unix::io::RawFd;
use std::sync;

#[link(name = "procutil", kind = "static")]
extern "C" {
    // sendfds.c
    fn sendfds(sockfd: c_int, fds: *const c_int, fdlen: size_t) -> ssize_t;

    // sighandlers.c
    fn setupsignalhandler(pid: pid_t, pgid: pid_t) -> c_int;
    fn restoresignalhandler() -> c_int;
}

/// Returns the effective uid of the current process.
pub fn get_effective_uid() -> u32 {
    unsafe { libc::geteuid() }
}

/// Returns the umask of the current process.
///
/// # Safety
///
/// This is unsafe because the umask value is temporarily changed, and
/// the change can be observed from the other threads. Don't call this in
/// multi-threaded context.
pub unsafe fn get_umask() -> u32 {
    let mask = libc::umask(0);
    libc::umask(mask);
    mask
}

/// Changes the given fd to blocking mode.
pub fn set_blocking_fd(fd: RawFd) -> io::Result<()> {
    let flags = unsafe { libc::fcntl(fd, libc::F_GETFL) };
    if flags < 0 {
        return Err(io::Error::last_os_error());
    }
    let r =
        unsafe { libc::fcntl(fd, libc::F_SETFL, flags & !libc::O_NONBLOCK) };
    if r < 0 {
        return Err(io::Error::last_os_error());
    }
    Ok(())
}

/// Sends file descriptors via the given socket.
pub fn send_raw_fds(sock_fd: RawFd, fds: &[RawFd]) -> io::Result<()> {
    let r = unsafe { sendfds(sock_fd, fds.as_ptr(), fds.len() as size_t) };
    if r < 0 {
        return Err(io::Error::last_os_error());
    }
    Ok(())
}

static SETUP_SIGNAL_HANDLER: sync::Once = sync::Once::new();
static RESTORE_SIGNAL_HANDLER: sync::Once = sync::Once::new();

/// Installs signal handlers to forward signals to the server.
///
/// # Safety
///
/// This touches global states, and thus synchronized as a one-time
/// initialization function.
pub fn setup_signal_handler_once(
    pid: u32,
    pgid: Option<u32>,
) -> io::Result<()> {
    let pid_signed = pid as i32;
    let pgid_signed = pgid.map(|n| n as i32).unwrap_or(0);
    let mut r = 0;
    SETUP_SIGNAL_HANDLER.call_once(|| {
        r = unsafe { setupsignalhandler(pid_signed, pgid_signed) };
    });
    if r < 0 {
        return Err(io::Error::last_os_error());
    }
    Ok(())
}

/// Restores the original signal handlers.
///
/// # Safety
///
/// This touches global states, and thus synchronized as a one-time
/// initialization function.
pub fn restore_signal_handler_once() -> io::Result<()> {
    let mut r = 0;
    RESTORE_SIGNAL_HANDLER.call_once(|| {
        r = unsafe { restoresignalhandler() };
    });
    if r < 0 {
        return Err(io::Error::last_os_error());
    }
    Ok(())
}