1: /* Copy memory to memory until the specified number of bytes
    2:    has been copied with error checking.  Overlap is handled correctly.
    3:    Copyright (C) 1991,1995,1996,1997,2003,2004 Free Software Foundation, Inc.
    4:    This file is part of the GNU C Library.
    5:    Contributed by Torbjorn Granlund (tege@sics.se).
    6: 
    7:    The GNU C Library is free software; you can redistribute it and/or
    8:    modify it under the terms of the GNU Lesser General Public
    9:    License as published by the Free Software Foundation; either
   10:    version 2.1 of the License, or (at your option) any later version.
   11: 
   12:    The GNU C Library is distributed in the hope that it will be useful,
   13:    but WITHOUT ANY WARRANTY; without even the implied warranty of
   14:    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   15:    Lesser General Public License for more details.
   16: 
   17:    You should have received a copy of the GNU Lesser General Public
   18:    License along with the GNU C Library; if not, write to the Free
   19:    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   20:    02111-1307 USA.  */
   21: 
   22: #include <string.h>
   23: #include <memcopy.h>
   24: #include <pagecopy.h>
   25: 
   26: void *
   27: __memmove_chk (dest, src, len, destlen)
   28:      void *dest;
   29:      const void *src;
   30:      size_t len;
   31:      size_t destlen;
   32: {
   33:   if (__builtin_expect (destlen < len, 0))
   34:     __chk_fail ();
   35: 
   36:   unsigned long int dstp = (long int) dest;
   37:   unsigned long int srcp = (long int) src;
   38: 
   39:   /* This test makes the forward copying code be used whenever possible.
   40:      Reduces the working set.  */
   41:   if (dstp - srcp >= len)       /* *Unsigned* compare!  */
   42:     {
   43:       /* Copy from the beginning to the end.  */
   44: 
   45:       /* If there not too few bytes to copy, use word copy.  */
   46:       if (len >= OP_T_THRES)
   47:         {
   48:           /* Copy just a few bytes to make DSTP aligned.  */
   49:           len -= (-dstp) % OPSIZ;
   50:           BYTE_COPY_FWD (dstp, srcp, (-dstp) % OPSIZ);
   51: 
   52:           /* Copy whole pages from SRCP to DSTP by virtual address
   53:              manipulation, as much as possible.  */
   54: 
   55:           PAGE_COPY_FWD_MAYBE (dstp, srcp, len, len);
   56: 
   57:           /* Copy from SRCP to DSTP taking advantage of the known
   58:              alignment of DSTP.  Number of bytes remaining is put
   59:              in the third argument, i.e. in LEN.  This number may
   60:              vary from machine to machine.  */
   61: 
   62:           WORD_COPY_FWD (dstp, srcp, len, len);
   63: 
   64:           /* Fall out and copy the tail.  */
   65:         }
   66: 
   67:       /* There are just a few bytes to copy.  Use byte memory operations.  */
   68:       BYTE_COPY_FWD (dstp, srcp, len);
   69:     }
   70:   else
   71:     {
   72:       /* Copy from the end to the beginning.  */
   73:       srcp += len;
   74:       dstp += len;
   75: 
   76:       /* If there not too few bytes to copy, use word copy.  */
   77:       if (len >= OP_T_THRES)
   78:         {
   79:           /* Copy just a few bytes to make DSTP aligned.  */
   80:           len -= dstp % OPSIZ;
   81:           BYTE_COPY_BWD (dstp, srcp, dstp % OPSIZ);
   82: 
   83:           /* Copy from SRCP to DSTP taking advantage of the known
   84:              alignment of DSTP.  Number of bytes remaining is put
   85:              in the third argument, i.e. in LEN.  This number may
   86:              vary from machine to machine.  */
   87: 
   88:           WORD_COPY_BWD (dstp, srcp, len, len);
   89: 
   90:           /* Fall out and copy the tail.  */
   91:         }
   92: 
   93:       /* There are just a few bytes to copy.  Use byte memory operations.  */
   94:       BYTE_COPY_BWD (dstp, srcp, len);
   95:     }
   96: 
   97:   return dest;
   98: }