wcsmbs/mbsnrtowcs.c

   1 /* Copyright (C) 1996, 1997 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1996.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <errno.h>
  21 #include <wchar.h>
  22
  23 #ifndef EILSEQ
  24 #define EILSEQ EINVAL
  25 #endif
  26
  27
  28 /* We don't need the state really because we don't have shift states
  29    to maintain between calls to this function.  */
  30 static mbstate_t internal;
  31
  32 /* This is a non-standard function but it is very useful in the
  33    implementation of stdio because we have to deal with unterminated
  34    buffers.  At most NMC bytes will be converted.  */
  35 size_t
  36 __mbsnrtowcs (dst, src, nmc, len, ps)
  37      wchar_t *dst;
  38      const char **src;
  39      size_t nmc;
  40      size_t len;
  41      mbstate_t *ps;
  42 {
  43   size_t written = 0;
  44   const char *run = *src;
  45   const char *last = run + nmc;
  46
  47   if (ps == NULL)
  48     ps = &internal;
  49
  50   if (dst == NULL)
  51     /* The LEN parameter has to be ignored if we don't actually write
  52        anything.  */
  53     len = ~0;
  54
  55   /* Copy all words.  */
  56   while (written < len && run < last)
  57     {
  58       wchar_t value;
  59       size_t count;
  60       unsigned char byte = *run++;
  61
  62       /* We expect a start of a new multibyte character.  */
  63       if (byte < 0x80)
  64         {
  65           /* One byte sequence.  */
  66           count = 0;
  67           value = byte;
  68         }
  69       else if ((byte & 0xe0) == 0xc0)
  70         {
  71           count = 1;
  72           value = byte & 0x1f;
  73         }
  74       else if ((byte & 0xf0) == 0xe0)
  75         {
  76           /* We expect three bytes.  */
  77           count = 2;
  78           value = byte & 0x0f;
  79         }
  80       else if ((byte & 0xf8) == 0xf0)
  81         {
  82           /* We expect four bytes.  */
  83           count = 3;
  84           value = byte & 0x07;
  85         }
  86       else if ((byte & 0xfc) == 0xf8)
  87         {
  88           /* We expect five bytes.  */
  89           count = 4;
  90           value = byte & 0x03;
  91         }
  92       else if ((byte & 0xfe) == 0xfc)
  93         {
  94           /* We expect six bytes.  */
  95           count = 5;
  96           value = byte & 0x01;
  97         }
  98       else
  99         {
 100           /* This is an illegal encoding.  */
 101           __set_errno (EILSEQ);
 102           return (size_t) -1;
 103         }
 104
 105       /* Read the possible remaining bytes.  */
 106       while (count-- > 0)
 107         {
 108           byte = *run++;
 109
 110           if ((byte & 0xc0) != 0x80)
 111             {
 112               /* This is an illegal encoding.  */
 113               __set_errno (EILSEQ);
 114               return (size_t) -1;
 115             }
 116
 117           value <<= 6;
 118           value |= byte & 0x3f;
 119         }
 120
 121       /* Store value is required.  */
 122       if (dst != NULL)
 123         *dst++ = value;
 124
 125       /* The whole sequence is read.  Check whether end of string is
 126          reached.  */
 127       if (value == L'\0')
 128         {
 129           /* Found the end of the string.  */
 130           *src = NULL;
 131           return written;
 132         }
 133
 134       /* Increment counter of produced words.  */
 135       ++written;
 136     }
 137
 138   /* Store address of next byte to process.  */
 139   *src = run;
 140
 141   return written;
 142 }
 143 weak_alias (__mbsnrtowcs, mbsnrtowcs)