wcsmbs/wcpncpy.c

   1 /* Copyright (C) 1996-2015 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <wchar.h>
  20
  21 #ifdef WCPNCPY
  22 # define __wcpncpy WCPNCPY
  23 #endif
  24
  25 /* Copy no more than N wide-characters of SRC to DEST, returning the
  26    address of the last character written into DEST.  */
  27 wchar_t *
  28 __wcpncpy (dest, src, n)
  29      wchar_t *dest;
  30      const wchar_t *src;
  31      size_t n;
  32 {
  33   wint_t c;
  34   wchar_t *const s = dest;
  35
  36   if (n >= 4)
  37     {
  38       size_t n4 = n >> 2;
  39
  40       for (;;)
  41         {
  42           c = *src++;
  43           *dest++ = c;
  44           if (c == L'\0')
  45             break;
  46           c = *src++;
  47           *dest++ = c;
  48           if (c == L'\0')
  49             break;
  50           c = *src++;
  51           *dest++ = c;
  52           if (c == L'\0')
  53             break;
  54           c = *src++;
  55           *dest++ = c;
  56           if (c == L'\0')
  57             break;
  58           if (--n4 == 0)
  59             goto last_chars;
  60         }
  61       n -= dest - s;
  62       goto zero_fill;
  63     }
  64
  65  last_chars:
  66   n &= 3;
  67   if (n == 0)
  68     return dest;
  69
  70   for (;;)
  71     {
  72       c = *src++;
  73       --n;
  74       *dest++ = c;
  75       if (c == L'\0')
  76         break;
  77       if (n == 0)
  78         return dest;
  79     }
  80
  81  zero_fill:
  82   while (n-- > 0)
  83     dest[n] = L'\0';
  84
  85   return dest - 1;
  86 }
  87
  88 #ifndef WCPNCPY
  89 weak_alias (__wcpncpy, wcpncpy)
  90 #endif