1  /* Copy a file from one path to another.
       2     Copyright (C) 2020-2023 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 <fcntl.h>
      20  #include <support/check.h>
      21  #include <support/support.h>
      22  #include <support/xunistd.h>
      23  
      24  void
      25  support_copy_file (const char *from, const char *to)
      26  {
      27    struct stat st;
      28    xstat (from, &st);
      29    int fd_from = xopen (from, O_RDONLY, 0);
      30    mode_t mode = st.st_mode & 0777;
      31    int fd_to = xopen (to, O_WRONLY | O_TRUNC | O_CREAT, mode);
      32    ssize_t ret = support_copy_file_range (fd_from, NULL, fd_to, NULL,
      33                                           st.st_size, 0);
      34    if (ret < 0)
      35      FAIL_EXIT1 ("copying from \"%s\" to \"%s\": %m", from, to);
      36    if (ret != st.st_size)
      37      FAIL_EXIT1 ("copying from \"%s\" to \"%s\": only %zd of %llu bytes copied",
      38                  from, to, ret, (unsigned long long int) st.st_size);
      39    if (fchmod (fd_to, mode) < 0)
      40      FAIL_EXIT1 ("fchmod on %s to 0%o: %m", to, mode);
      41    xclose (fd_to);
      42    xclose (fd_from);
      43  }