support/support_copy_file.c

   1 /* Copy a file from one path to another.
   2    Copyright (C) 2020-2021 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 stat64 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 }