Function source_is_dst_backup

src/copy.c:1586–1605

Return true if the source file with basename SRCBASE and status SRC_ST is likely to be the simple backup file for DST_DIRFD+DST_RELNAME. */

/* Return true if the source file with basename SRCBASE and status SRC_ST
   is likely to be the simple backup file for DST_DIRFD+DST_RELNAME.  */
static bool
source_is_dst_backup (char const *srcbase, struct stat const *src_st,
                      int dst_dirfd, char const *dst_relname)
{
  size_t srcbaselen = strlen (srcbase);
  char const *dstbase = last_component (dst_relname);
  size_t dstbaselen = strlen (dstbase);
  size_t suffixlen = strlen (simple_backup_suffix);
  if (! (srcbaselen == dstbaselen + suffixlen
         && memeq (srcbase, dstbase, dstbaselen)
         && streq (srcbase + dstbaselen, simple_backup_suffix)))
    return false;
  char *dst_back = subst_suffix (dst_relname,
                                 dst_relname + strlen (dst_relname),
                                 simple_backup_suffix);
  struct stat dst_back_sb;
  int dst_back_status = fstatat (dst_dirfd, dst_back, &dst_back_sb, 0);
  free (dst_back);
  return dst_back_status == 0 && psame_inode (src_st, &dst_back_sb);
}

/* Copy the file SRC_NAME to the file DST_NAME aka DST_DIRFD+DST_RELNAME.
   If NONEXISTENT_DST is positive, DST_NAME does not exist even as a