mergerfs/src/fs_copy_file_range_linux.icpp

/*
  ISC License

  Copyright (c) 2018, Antonio SJ Musumeci <trapexit@spawn.link>

  Permission to use, copy, modify, and/or distribute this software for any
  purpose with or without fee is hereby granted, provided that the above
  copyright notice and this permission notice appear in all copies.

  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#define _GNU_SOURCE

#include "errno.hpp"

#include <stdio.h>
#include <sys/types.h>
#include <sys/syscall.h>
#include <unistd.h>

static
loff_t
copy_file_range_(int           fd_in_,
                 loff_t       *off_in_,
                 int           fd_out_,
                 loff_t       *off_out_,
                 size_t        len_,
                 unsigned int  flags_)
{
#ifdef SYS_copy_file_range
  return ::syscall(SYS_copy_file_range,
                   fd_in_,
                   off_in_,
                   fd_out_,
                   off_out_,
                   len_,
                   flags_);
#else
  return (errno=EOPNOTSUPP,-1);
#endif
}

namespace fs
{
  ssize_t
  copy_file_range(const int           fd_in_,
                  loff_t             *off_in_,
                  const int           fd_out_,
                  loff_t             *off_out_,
                  const size_t        len_,
                  const unsigned int  flags_)
  {
    return ::copy_file_range_(fd_in_,
                              off_in_,
                              fd_out_,
                              off_out_,
                              len_,
                              flags_);
  }

  ssize_t
  copy_file_range(const int           fd_in_,
                  const int           fd_out_,
                  const size_t        len_,
                  const unsigned int  flags_)
  {
    loff_t off_in;
    loff_t off_out;

    off_in  = 0;
    off_out = 0;

    return fs::copy_file_range(fd_in_,
                               &off_in,
                               fd_out_,
                               &off_out,
                               len_,
                               flags_);
  }
}