glibc/sysdeps/generic/strncpy.c

87 lines
1.7 KiB
C

/* Copyright (C) 1991, 1997 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <string.h>
#include <memcopy.h>
#undef strncpy
char *
strncpy (s1, s2, n)
char *s1;
const char *s2;
size_t n;
{
reg_char c;
char *s = s1;
--s1;
if (n >= 4)
{
size_t n4 = n >> 2;
for (;;)
{
c = *s2++;
*++s1 = c;
if (c == '\0')
break;
c = *s2++;
*++s1 = c;
if (c == '\0')
break;
c = *s2++;
*++s1 = c;
if (c == '\0')
break;
c = *s2++;
*++s1 = c;
if (c == '\0')
break;
if (--n4 == 0)
goto last_chars;
}
n = n - (s1 - s) - 1;
if (n == 0)
return s;
goto zero_fill;
}
last_chars:
n &= 3;
if (n == 0)
return s;
do
{
c = *s2++;
*++s1 = c;
if (--n == 0)
return s;
}
while (c != '\0');
zero_fill:
do
*++s1 = '\0';
while (--n > 0);
return s;
}