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glibc  2.9
memcpy_chk.c
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00001 /* Copy memory to memory until the specified number of bytes
00002    has been copied with error checking.  Overlap is NOT handled correctly.
00003    Copyright (C) 1991, 1997, 2003, 2004 Free Software Foundation, Inc.
00004    This file is part of the GNU C Library.
00005    Contributed by Torbjorn Granlund (tege@sics.se).
00006 
00007    The GNU C Library is free software; you can redistribute it and/or
00008    modify it under the terms of the GNU Lesser General Public
00009    License as published by the Free Software Foundation; either
00010    version 2.1 of the License, or (at your option) any later version.
00011 
00012    The GNU C Library is distributed in the hope that it will be useful,
00013    but WITHOUT ANY WARRANTY; without even the implied warranty of
00014    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015    Lesser General Public License for more details.
00016 
00017    You should have received a copy of the GNU Lesser General Public
00018    License along with the GNU C Library; if not, write to the Free
00019    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00020    02111-1307 USA.  */
00021 
00022 #include <string.h>
00023 #include <memcopy.h>
00024 #include <pagecopy.h>
00025 
00026 void *
00027 __memcpy_chk (dstpp, srcpp, len, dstlen)
00028      void *dstpp;
00029      const void *srcpp;
00030      size_t len;
00031      size_t dstlen;
00032 {
00033   if (__builtin_expect (dstlen < len, 0))
00034     __chk_fail ();
00035 
00036   unsigned long int dstp = (long int) dstpp;
00037   unsigned long int srcp = (long int) srcpp;
00038 
00039   /* Copy from the beginning to the end.  */
00040 
00041   /* If there not too few bytes to copy, use word copy.  */
00042   if (len >= OP_T_THRES)
00043     {
00044       /* Copy just a few bytes to make DSTP aligned.  */
00045       len -= (-dstp) % OPSIZ;
00046       BYTE_COPY_FWD (dstp, srcp, (-dstp) % OPSIZ);
00047 
00048       /* Copy whole pages from SRCP to DSTP by virtual address manipulation,
00049         as much as possible.  */
00050 
00051       PAGE_COPY_FWD_MAYBE (dstp, srcp, len, len);
00052 
00053       /* Copy from SRCP to DSTP taking advantage of the known alignment of
00054         DSTP.  Number of bytes remaining is put in the third argument,
00055         i.e. in LEN.  This number may vary from machine to machine.  */
00056 
00057       WORD_COPY_FWD (dstp, srcp, len, len);
00058 
00059       /* Fall out and copy the tail.  */
00060     }
00061 
00062   /* There are just a few bytes to copy.  Use byte memory operations.  */
00063   BYTE_COPY_FWD (dstp, srcp, len);
00064 
00065   return dstpp;
00066 }