debug/memset_chk.c

   1 /* Copyright (C) 1991, 1997, 2003, 2004, 2005 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <string.h>
  19 #include <memcopy.h>
  20
  21 void *
  22 __memset_chk (dstpp, c, len, dstlen)
  23      void *dstpp;
  24      int c;
  25      size_t len;
  26      size_t dstlen;
  27 {
  28   if (__builtin_expect (dstlen < len, 0))
  29     __chk_fail ();
  30
  31   long int dstp = (long int) dstpp;
  32
  33   if (len >= 8)
  34     {
  35       size_t xlen;
  36       op_t cccc;
  37
  38       cccc = (unsigned char) c;
  39       cccc |= cccc << 8;
  40       cccc |= cccc << 16;
  41       if (OPSIZ > 4)
  42         /* Do the shift in two steps to avoid warning if long has 32 bits.  */
  43         cccc |= (cccc << 16) << 16;
  44
  45       /* There are at least some bytes to set.
  46          No need to test for LEN == 0 in this alignment loop.  */
  47       while (dstp % OPSIZ != 0)
  48         {
  49           ((byte *) dstp)[0] = c;
  50           dstp += 1;
  51           len -= 1;
  52         }
  53
  54       /* Write 8 `op_t' per iteration until less than 8 `op_t' remain.  */
  55       xlen = len / (OPSIZ * 8);
  56       while (xlen > 0)
  57         {
  58           ((op_t *) dstp)[0] = cccc;
  59           ((op_t *) dstp)[1] = cccc;
  60           ((op_t *) dstp)[2] = cccc;
  61           ((op_t *) dstp)[3] = cccc;
  62           ((op_t *) dstp)[4] = cccc;
  63           ((op_t *) dstp)[5] = cccc;
  64           ((op_t *) dstp)[6] = cccc;
  65           ((op_t *) dstp)[7] = cccc;
  66           dstp += 8 * OPSIZ;
  67           xlen -= 1;
  68         }
  69       len %= OPSIZ * 8;
  70
  71       /* Write 1 `op_t' per iteration until less than OPSIZ bytes remain.  */
  72       xlen = len / OPSIZ;
  73       while (xlen > 0)
  74         {
  75           ((op_t *) dstp)[0] = cccc;
  76           dstp += OPSIZ;
  77           xlen -= 1;
  78         }
  79       len %= OPSIZ;
  80     }
  81
  82   /* Write the last few bytes.  */
  83   while (len > 0)
  84     {
  85       ((byte *) dstp)[0] = c;
  86       dstp += 1;
  87       len -= 1;
  88     }
  89
  90   return dstpp;
  91 }