newlib/libc/stdio/fgetwc.c

   1 /*-
   2  * Copyright (c) 2002-2004 Tim J. Robbins.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 /*
  28 FUNCTION
  29 <<fgetwc>>, <<getwc>>, <<fgetwc_unlocked>>, <<getwc_unlocked>>---get a wide character from a file or stream
  30
  31 INDEX
  32         fgetwc
  33 INDEX
  34         fgetwc_unlocked
  35 INDEX
  36         _fgetwc_r
  37 INDEX
  38         _fgetwc_unlocked_r
  39 INDEX
  40         getwc
  41 INDEX
  42         getwc_unlocked
  43 INDEX
  44         _getwc_r
  45 INDEX
  46         _getwc_unlocked_r
  47
  48 SYNOPSIS
  49         #include <stdio.h>
  50         #include <wchar.h>
  51         wint_t fgetwc(FILE *<[fp]>);
  52
  53         #define _GNU_SOURCE
  54         #include <stdio.h>
  55         #include <wchar.h>
  56         wint_t fgetwc_unlocked(FILE *<[fp]>);
  57
  58         #include <stdio.h>
  59         #include <wchar.h>
  60         wint_t _fgetwc_r(struct _reent *<[ptr]>, FILE *<[fp]>);
  61
  62         #include <stdio.h>
  63         #include <wchar.h>
  64         wint_t _fgetwc_unlocked_r(struct _reent *<[ptr]>, FILE *<[fp]>);
  65
  66         #include <stdio.h>
  67         #include <wchar.h>
  68         wint_t getwc(FILE *<[fp]>);
  69
  70         #define _GNU_SOURCE
  71         #include <stdio.h>
  72         #include <wchar.h>
  73         wint_t getwc_unlocked(FILE *<[fp]>);
  74
  75         #include <stdio.h>
  76         #include <wchar.h>
  77         wint_t _getwc_r(struct _reent *<[ptr]>, FILE *<[fp]>);
  78
  79         #include <stdio.h>
  80         #include <wchar.h>
  81         wint_t _getwc_unlocked_r(struct _reent *<[ptr]>, FILE *<[fp]>);
  82
  83 DESCRIPTION
  84 Use <<fgetwc>> to get the next wide character from the file or stream
  85 identified by <[fp]>.  As a side effect, <<fgetwc>> advances the file's
  86 current position indicator.
  87
  88 <<fgetwc_unlocked>> is a non-thread-safe version of <<fgetwc>>.
  89 <<fgetwc_unlocked>> may only safely be used within a scope
  90 protected by flockfile() (or ftrylockfile()) and funlockfile().  This
  91 function may safely be used in a multi-threaded program if and only
  92 if they are called while the invoking thread owns the (FILE *)
  93 object, as is the case after a successful call to the flockfile() or
  94 ftrylockfile() functions.  If threads are disabled, then
  95 <<fgetwc_unlocked>> is equivalent to <<fgetwc>>.
  96
  97 The <<getwc>> and <<getwc_unlocked>> functions or macros functions identically
  98 to <<fgetwc>> and <<fgetwc_unlocked>>.  It may be implemented as a macro, and
  99 may evaluate its argument more than once. There is no reason ever to use it.
 100
 101 <<_fgetwc_r>>, <<_getwc_r>>, <<_fgetwc_unlocked_r>>, and <<_getwc_unlocked_r>>
 102 are simply reentrant versions of the above functions that are passed the
 103 additional reentrant structure pointer argument: <[ptr]>.
 104
 105 RETURNS
 106 The next wide character cast to <<wint_t>>, unless there is no more data,
 107 or the host system reports a read error; in either of these situations,
 108 <<fgetwc>> and <<getwc>> return <<WEOF>>.
 109
 110 You can distinguish the two situations that cause an <<EOF>> result by
 111 using the <<ferror>> and <<feof>> functions.
 112
 113 PORTABILITY
 114 <<fgetwc>> and <<getwc>> are required by C99 and POSIX.1-2001.
 115
 116 <<fgetwc_unlocked>> and <<getwc_unlocked>> are GNU extensions.
 117 */
 118
 119 #include <_ansi.h>
 120 #include <reent.h>
 121 #include <errno.h>
 122 #include <stdio.h>
 123 #include <stdlib.h>
 124 #include <wchar.h>
 125 #include "local.h"
 126
 127 wint_t
 128 __fgetwc (struct _reent *ptr,
 129         register FILE *fp)
 130 {
 131   wchar_t wc;
 132   size_t nconv;
 133
 134   if (fp->_r <= 0 && __srefill_r (ptr, fp))
 135     return (WEOF);
 136   if (MB_CUR_MAX == 1)
 137     {
 138       /* Fast path for single-byte encodings. */
 139       wc = *fp->_p++;
 140       fp->_r--;
 141       return (wc);
 142     }
 143   do
 144     {
 145       nconv = _mbrtowc_r (ptr, &wc, (char *) fp->_p, fp->_r, &fp->_mbstate);
 146       if (nconv == (size_t)-1)
 147         break;
 148       else if (nconv == (size_t)-2)
 149         continue;
 150       else if (nconv == 0)
 151         {
 152           /*
 153            * Assume that the only valid representation of
 154            * the null wide character is a single null byte.
 155            */
 156           fp->_p++;
 157           fp->_r--;
 158           return (L'\0');
 159         }
 160       else
 161         {
 162           fp->_p += nconv;
 163           fp->_r -= nconv;
 164           return (wc);
 165         }
 166     }
 167   while (__srefill_r(ptr, fp) == 0);
 168   fp->_flags |= __SERR;
 169   errno = EILSEQ;
 170   return (WEOF);
 171 }
 172
 173 wint_t
 174 _fgetwc_r (struct _reent *ptr,
 175         register FILE *fp)
 176 {
 177   wint_t r;
 178
 179   _newlib_flockfile_start (fp);
 180   if (ORIENT(fp, 1) != 1)
 181     r = WEOF;
 182   else
 183     r = __fgetwc (ptr, fp);
 184   _newlib_flockfile_end (fp);
 185   return r;
 186 }
 187
 188 wint_t
 189 fgetwc (FILE *fp)
 190 {
 191   struct _reent *reent = _REENT;
 192
 193   CHECK_INIT(reent, fp);
 194   return _fgetwc_r (reent, fp);
 195 }