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1//
2// fgetwc.cpp
3//
4// Copyright (c) Microsoft Corporation. All rights reserved.
5//
6// Functions that read the next wide character from a stream and return it. If
7// the read causes the stream to reach EOF, WEOF is returned and the EOF bit is
8// set on the stream.
9//
10#include <corecrt_internal_stdio.h>
11
12
13
14extern "C" wint_t __cdecl _fgetwc_nolock(FILE* const public_stream)
15{
16 __crt_stdio_stream const stream(public_stream);
17
18 // If the stream is backed by a real file and is open in a Unicode text mode,
19 // we need to read two bytes (note that we read two bytes for both UTF-8 and
20 // UTF-16 backed streams, since lowio translates UTF-8 to UTF-16 when we read.
21 if (!stream.is_string_backed() &&
22 _textmode_safe(_fileno(stream.public_stream())) != __crt_lowio_text_mode::ansi)
23 {
24 wchar_t wc;
25
26 // Compose the wide character by reading byte-by-byte from the stream:
27 char* const wc_first = reinterpret_cast<char*>(&wc);
28 char* const wc_last = wc_first + sizeof(wc);
29
30 for (char* it = wc_first; it != wc_last; ++it)
31 {
32 int const c = _getc_nolock(stream.public_stream());
33 if (c == EOF)
34 return WEOF;
35
36 *it = static_cast<char>(c);
37 }
38
39 return wc;
40 }
41
42 if (!stream.is_string_backed() &&
43 (_osfile_safe(_fileno(stream.public_stream())) & FTEXT))
44 {
45 int size = 1;
46 int ch;
47 char mbc[4];
48 wchar_t wch;
49
50 /* text (multi-byte) mode */
51 if ((ch = _getc_nolock(stream.public_stream())) == EOF)
52 return WEOF;
53
54 mbc[0] = static_cast<char>(ch);
55
56 if (isleadbyte(static_cast<unsigned char>(mbc[0])))
57 {
58 if ((ch = _getc_nolock(stream.public_stream())) == EOF)
59 {
60 ungetc(mbc[0], stream.public_stream());
61 return WEOF;
62 }
63 mbc[1] = static_cast<char>(ch);
64 size = 2;
65 }
66
67 if (mbtowc(&wch, mbc, size) == -1)
68 {
69 // Conversion failed! Set errno and return failure:
70 errno = EILSEQ;
71 return WEOF;
72 }
73
74 return wch;
75 }
76
77 // binary (Unicode) mode
78 if (stream->_cnt >= static_cast<int>(sizeof(wchar_t)))
79 {
80 stream->_cnt -= static_cast<int>(sizeof(wchar_t));
81 return *reinterpret_cast<wchar_t*&>(stream->_ptr)++;
82 }
83 else
84 {
85 return static_cast<wint_t>(__acrt_stdio_refill_and_read_wide_nolock(stream.public_stream()));
86 }
87}
88
89
90
91extern "C" wint_t __cdecl _getwc_nolock(FILE* const stream)
92{
93 return _fgetwc_nolock(stream);
94}
95
96
97
98extern "C" wint_t __cdecl fgetwc(FILE* const stream)
99{
100 _VALIDATE_RETURN(stream != nullptr, EINVAL, WEOF);
101
102 wint_t return_value = 0;
103
104 _lock_file(stream);
105 __try
106 {
107 return_value = _fgetwc_nolock(stream);
108 }
109 __finally
110 {
111 _unlock_file(stream);
112 }
113 __endtry
114
115 return return_value;
116}
117
118
119
120extern "C" wint_t __cdecl getwc(FILE* const stream)
121{
122 return fgetwc(stream);
123}
124
125
126
127extern "C" wint_t __cdecl _fgetwchar()
128{
129 return fgetwc(stdin);
130}
131
132
133
134extern "C" wint_t __cdecl getwchar()
135{
136 return _fgetwchar();
137}