summary refs log tree commit diff
path: root/wcsmbs/mbrtowc.c
blob: 8b4dbe2912e517408ddb4cc9c2b926d662b1695d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
/* Copyright (C) 1996 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1996.

   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 <errno.h>
#include <wchar.h>

#ifndef EILSEQ
#define EILSEQ EINVAL
#endif


static mbstate_t internal;

size_t
__mbrtowc (wchar_t *pwc, const char *s, size_t n, mbstate_t *ps)
{
  size_t used = 0;

  if (ps == NULL)
    ps = &internal;

  if (s == NULL)
    {
      /* See first paragraph of description in 7.16.6.3.2.  */
      pwc = NULL;
      s = "";
      n = 1;
    }

  if (n > 0)
    {
      if (ps->count == 0)
	{
	  unsigned char byte = (unsigned char) *s++;
	  ++used;

	  /* We must look for a possible first byte of a UTF8 sequence.  */
	  if (byte < 0x80)
	    {
	      /* One byte sequence.  */
	      if (pwc != NULL)
		*pwc = (wchar_t) byte;
	      return byte ? used : 0;
	    }

	  if ((byte & 0xc0) == 0x80 || (byte & 0xfe) == 0xfe)
	    {
	      /* Oh, oh.  An encoding error.  */
	      __set_errno (EILSEQ);
	      return (size_t) -1;
	    }

	  if ((byte & 0xe0) == 0xc0)
	    {
	      /* We expect two bytes.  */
	      ps->count = 1;
	      ps->value = byte & 0x1f;
	    }
	  else if ((byte & 0xf0) == 0xe0)
	    {
	      /* We expect three bytes.  */
	      ps->count = 2;
	      ps->value = byte & 0x0f;
	    }
	  else if ((byte & 0xf8) == 0xf0)
	    {
	      /* We expect four bytes.  */
	      ps->count = 3;
	      ps->value = byte & 0x07;
	    }
	  else if ((byte & 0xfc) == 0xf8)
	    {
	      /* We expect five bytes.  */
	      ps->count = 4;
	      ps->value = byte & 0x03;
	    }
	  else
	    {
	      /* We expect six bytes.  */
	      ps->count = 5;
	      ps->value = byte & 0x01;
	    }
	}

      /* We know we have to handle a multibyte character and there are
	 some more bytes to read.  */
      while (used < n)
	{
	  /* The second to sixths byte must be of the form 10xxxxxx.  */
	  unsigned char byte = (unsigned char) *s++;
	  ++used;

	  if ((byte & 0xc0) != 0x80)
	    {
	      /* Oh, oh.  An encoding error.  */
	      __set_errno (EILSEQ);
	      return (size_t) -1;
	    }

	  ps->value <<= 6;
	  ps->value |= byte & 0x3f;

	  if (--ps->count == 0)
	    {
	      /* The character is finished.  */
	      if (pwc != NULL)
		*pwc = (wchar_t) ps->value;
	      return ps->value ? used : 0;
	    }
	}
    }

  return (size_t) -2;
}
weak_alias (__mbrtowc, mbrtowc)