1  /* sendfile -- copy data directly from one file descriptor to another
       2     Copyright (C) 2002-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <sys/sendfile.h>
      20  #include <stddef.h>
      21  
      22  /* Send COUNT bytes from file associated with IN_FD starting at OFFSET to
      23     descriptor OUT_FD.  */
      24  ssize_t
      25  sendfile (int out_fd, int in_fd, off_t *offset, size_t count)
      26  {
      27    if (offset == NULL || sizeof (off_t) == sizeof (off64_t))
      28      return __sendfile64 (out_fd, in_fd, (off64_t *) offset, count);
      29    else
      30      {
      31        off64_t ofs = *offset;
      32        ssize_t ret = __sendfile64 (out_fd, in_fd, &ofs, count);
      33        *offset = ofs;
      34        return ret;
      35      }
      36  }