+ /* Check that the input file and output file are different. */
+ if (stat (argv[i], &sib) == 0
+ && sib.st_ino == sob.st_ino
+ /* POSIX emulating systems may support stat() but if the
+ underlying file system does not support a file serial number
+ of some kind then they will return 0 for the inode. So
+ two files with an inode of 0 may not actually be the same.
+ On real POSIX systems no ordinary file will ever have an
+ inode of 0. */
+ && sib.st_ino != 0
+ /* Different files may have the same inode number if they
+ reside on different devices, so check the st_dev field as
+ well. */
+ && sib.st_dev == sob.st_dev)