glibc/sysdeps/generic/stpncpy.c

100 lines
2.1 KiB
C

/* Copyright (C) 1993, 1995, 1996, 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. */
/* This is almost copied from strncpy.c, written by Torbjorn Granlund. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#ifdef _LIBC
# include <string.h>
#else
# include <sys/types.h>
#endif
#ifndef weak_alias
# define __stpncpy stpncpy
#endif
/* Copy no more than N characters of SRC to DEST, returning the address of
the terminating '\0' in DEST, if any, or else DEST + N. */
char *
__stpncpy (dest, src, n)
char *dest;
const char *src;
size_t n;
{
char c;
char *s = dest;
if (n >= 4)
{
size_t n4 = n >> 2;
for (;;)
{
c = *src++;
*dest++ = c;
if (c == '\0')
break;
c = *src++;
*dest++ = c;
if (c == '\0')
break;
c = *src++;
*dest++ = c;
if (c == '\0')
break;
c = *src++;
*dest++ = c;
if (c == '\0')
break;
if (--n4 == 0)
goto last_chars;
}
n -= dest - s;
goto zero_fill;
}
last_chars:
n &= 3;
if (n == 0)
return dest;
for (;;)
{
c = *src++;
--n;
*dest++ = c;
if (c == '\0')
break;
if (n == 0)
return dest;
}
zero_fill:
while (n-- > 0)
dest[n] = '\0';
return dest - 1;
}
#ifdef weak_alias
weak_alias (__stpncpy, stpncpy)
#endif