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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <string.h>
  20 #include <memcopy.h>
  21
  22 void *
  23 __memset_chk (dstpp, c, len, dstlen)
  24      void *dstpp;
  25      int c;
  26      size_t len;
  27      size_t dstlen;
  28 {
  29   if (__builtin_expect (dstlen < len, 0))
  30     __chk_fail ();
  31
  32   long int dstp = (long int) dstpp;
  33
  34   if (len >= 8)
  35     {
  36       size_t xlen;
  37       op_t cccc;
  38
  39       cccc = (unsigned char) c;
  40       cccc |= cccc << 8;
  41       cccc |= cccc << 16;
  42       if (OPSIZ > 4)
  43         /* Do the shift in two steps to avoid warning if long has 32 bits.  */
  44         cccc |= (cccc << 16) << 16;
  45
  46       /* There are at least some bytes to set.
  47          No need to test for LEN == 0 in this alignment loop.  */
  48       while (dstp % OPSIZ != 0)
  49         {
  50           ((byte *) dstp)[0] = c;
  51           dstp += 1;
  52           len -= 1;
  53         }
  54
  55       /* Write 8 `op_t' per iteration until less than 8 `op_t' remain.  */
  56       xlen = len / (OPSIZ * 8);
  57       while (xlen > 0)
  58         {
  59           ((op_t *) dstp)[0] = cccc;
  60           ((op_t *) dstp)[1] = cccc;
  61           ((op_t *) dstp)[2] = cccc;
  62           ((op_t *) dstp)[3] = cccc;
  63           ((op_t *) dstp)[4] = cccc;
  64           ((op_t *) dstp)[5] = cccc;
  65           ((op_t *) dstp)[6] = cccc;
  66           ((op_t *) dstp)[7] = cccc;
  67           dstp += 8 * OPSIZ;
  68           xlen -= 1;
  69         }
  70       len %= OPSIZ * 8;
  71
  72       /* Write 1 `op_t' per iteration until less than OPSIZ bytes remain.  */
  73       xlen = len / OPSIZ;
  74       while (xlen > 0)
  75         {
  76           ((op_t *) dstp)[0] = cccc;
  77           dstp += OPSIZ;
  78           xlen -= 1;
  79         }
  80       len %= OPSIZ;
  81     }
  82
  83   /* Write the last few bytes.  */
  84   while (len > 0)
  85     {
  86       ((byte *) dstp)[0] = c;
  87       dstp += 1;
  88       len -= 1;
  89     }
  90
  91   return dstpp;
  92 }