wcsmbs/wcsncpy.c

   1 /* Copyright (C) 1995-2015 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 WCSNCPY
  22 # define __wcsncpy WCSNCPY
  23 #endif
  24
  25 /* Copy no more than N wide-characters of SRC to DEST.  */
  26 wchar_t *
  27 __wcsncpy (dest, src, n)
  28      wchar_t *dest;
  29      const wchar_t *src;
  30      size_t n;
  31 {
  32   wint_t c;
  33   wchar_t *const s = dest;
  34
  35   --dest;
  36
  37   if (n >= 4)
  38     {
  39       size_t n4 = n >> 2;
  40
  41       for (;;)
  42         {
  43           c = *src++;
  44           *++dest = c;
  45           if (c == L'\0')
  46             break;
  47           c = *src++;
  48           *++dest = c;
  49           if (c == L'\0')
  50             break;
  51           c = *src++;
  52           *++dest = c;
  53           if (c == L'\0')
  54             break;
  55           c = *src++;
  56           *++dest = c;
  57           if (c == L'\0')
  58             break;
  59           if (--n4 == 0)
  60             goto last_chars;
  61         }
  62       n = n - (dest - s) - 1;
  63       if (n == 0)
  64         return s;
  65       goto zero_fill;
  66     }
  67
  68  last_chars:
  69   n &= 3;
  70   if (n == 0)
  71     return s;
  72
  73   do
  74     {
  75       c = *src++;
  76       *++dest = c;
  77       if (--n == 0)
  78         return s;
  79     }
  80   while (c != L'\0');
  81
  82  zero_fill:
  83   do
  84     *++dest = L'\0';
  85   while (--n > 0);
  86
  87   return s;
  88 }
  89 #ifndef WCSNCPY
  90 weak_alias (__wcsncpy, wcsncpy)
  91 #endif