/* Copy a file from one path to another.

   Copyright (C) 2020 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <https://www.gnu.org/licenses/>.  */

#include <fcntl.h>

#include <support/check.h>

#include <support/support.h>

#include <support/xunistd.h>

void

support_copy_file (const char *from, const char *to)

{

  struct stat64 st;

  xstat (from, &st);

  int fd_from = xopen (from, O_RDONLY, 0);

  mode_t mode = st.st_mode & 0777;

  int fd_to = xopen (to, O_WRONLY | O_TRUNC | O_CREAT, mode);

  ssize_t ret = support_copy_file_range (fd_from, NULL, fd_to, NULL,

                                         st.st_size, 0);

  if (ret < 0)

    FAIL_EXIT1 ("copying from \"%s\" to \"%s\": %m", from, to);

  if (ret != st.st_size)

    FAIL_EXIT1 ("copying from \"%s\" to \"%s\": only %zd of %llu bytes copied",

                from, to, ret, (unsigned long long int) st.st_size);

  if (fchmod (fd_to, mode) < 0)

    FAIL_EXIT1 ("fchmod on %s to 0%o: %m", to, mode);

  xclose (fd_to);

  xclose (fd_from);

}