Source

XEmacs / src / strcpy.c

/* This file is part of XEmacs.

XEmacs is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version.

XEmacs is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with XEmacs; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

/* Synched up with: Not in FSF. */

/* In SunOS 4.1.1 the strcpy function references memory past the last byte of 
   the string!  This will core dump if the memory following the last byte is 
   not mapped.

   Here are correct versions by hbs@lucid.com.
*/


#define ALIGNED(x) (!(((unsigned long) (x)) & (sizeof (unsigned long) - 1)))

#define MAGIC    0x7efefeff
#define HIGH_BIT_P(c) ((c) & hi_bit)
#define HAS_ZERO(c) (((((c) + magic) ^ (c)) & not_magic) != not_magic)

char *
strcpy (char *to, const char *from)
{
  char *return_value = to;
  if (to == from)
    return to;
  else if (ALIGNED (to) && ALIGNED (from))
    {
      unsigned long *to1 = (unsigned long *) to;
      const unsigned long *from1 = (const unsigned long *) from;
      unsigned long c;
      unsigned long magic = MAGIC;
      unsigned long not_magic = ~magic;
/*      unsigned long hi_bit = 0x80000000; */

      while ((c = *from1) != 0)
        {
          if (HAS_ZERO(c)) 
            {
              to = (char *) to1;
              from = (const char *) from1;
              goto slow_loop;
            }
          else
            {
              *to1 = c;
              to1++; 
              from1++;
            }
        }

      to = (char *) to1;
      *to = (char) 0;
      return return_value;
    }
  else
    {
      char c;

    slow_loop:

      while ((c = *from) != 0)
        {
          *to = c;
          to++;
          from++;
        }
      *to = (char) 0;
    }
  return return_value;
}
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