syscalls.rs

use std::os::unix::io::AsRawFd;
use std::ptr::null_mut;
use std::io::prelude::*;
use std::io::Error;
mod raw {
    pub use libc::{c_int, splice};
    const __NR_COPY_FILE_RANGE: ::libc::c_long = 326;
    #[inline]
    pub unsafe fn copy_file_range(fd_in: c_int, off_in: *mut ::libc::loff_t, fd_out: c_int, off_out: *mut ::libc::loff_t, len: usize, flags: u32) -> i64 {
        ::libc::syscall(__NR_COPY_FILE_RANGE, fd_in, off_in, fd_out, off_out, len, flags)
    }
}

pub fn splice<T: AsRawFd + Read, Y: AsRawFd + Write>(src: &mut T, dest: &mut Y, bytes: usize) -> ::std::io::Result<usize> {
    let res = unsafe { raw::splice(src.as_raw_fd(), null_mut(), dest.as_raw_fd(), null_mut(), bytes, 0) };
    if res < 0 {
        Err(::std::io::Error::last_os_error())
    }
    else { Ok(res as usize) }
}

    
pub fn copy(src: &mut ::std::fs::File, dest: &mut ::std::fs::File) -> ::std::io::Result<u64> {
    let len = src.metadata()?.len() as usize;
    /*loop {
        let res = unsafe { raw::copy_file_range(src.as_raw_fd(), null_mut(), dest.as_raw_fd(), null_mut(), 1024, 0) };
        if res < 0 {
            return Err(Error::last_os_error());
        }
        else if res == 0 {
            break;
        }
        else {
            written+=res as u64;
        }
    }*/
    let res = unsafe { raw::copy_file_range(src.as_raw_fd(), null_mut(), dest.as_raw_fd(), null_mut(), len, 0) };
    if res < 0 { Err(Error::last_os_error()) } else { Ok(res as u64) }

}

test.rs

#![feature(test)]
extern crate test;
extern crate zerocopy;
use zerocopy::zc::ZeroCopy;
use test::Bencher;
use std::io::prelude::*;
use std::fs::File;
#[bench]
fn zerocopy(b: &mut Bencher) {
    let mut src = File::open("foo").unwrap();
    let mut dest = File::create("foo.txt").unwrap();
    let len = src.metadata().unwrap().len() as usize;    
    b.iter(|| {
        ::zerocopy::copy(&mut src, &mut dest).unwrap();
        src.seek(::std::io::SeekFrom::Start(0));
        dest.seek(::std::io::SeekFrom::Start(0));
    });
    std::fs::remove_file("/tmp/foo.txt");

}
#[bench]
fn default(b: &mut Bencher) {
    let mut src = File::open("foo").unwrap();
    let mut dest = File::create("foo.txt").unwrap();

    b.iter(|| {
        ::std::io::copy(&mut src, &mut dest).unwrap();
        src.seek(::std::io::SeekFrom::Start(0));
        dest.seek(::std::io::SeekFrom::Start(0));

    });
    std::fs::remove_file("/tmp/foo.txt");
}