newlib/libc/stdio/fwide.c

   1 /*
   2 FUNCTION
   3 <<fwide>>---set and determine the orientation of a FILE stream
   4
   5 INDEX
   6         fwide
   7 INDEX
   8         _fwide_r
   9
  10 SYNOPSIS
  11         #include <wchar.h>
  12         int fwide(FILE *<[fp]>, int <[mode]>);
  13
  14         int _fwide_r(struct _reent *<[ptr]>, FILE *<[fp]>, int <[mode]>);
  15
  16 DESCRIPTION
  17 When <[mode]> is zero, the <<fwide>> function determines the current
  18 orientation of <[fp]>. It returns a value > 0 if <[fp]> is
  19 wide-character oriented, i.e. if wide character I/O is permitted but
  20 char I/O is disallowed. It returns a value < 0 if <[fp]> is byte
  21 oriented, i.e. if char I/O is permitted but wide character I/O is
  22 disallowed. It returns zero if <[fp]> has no orientation yet; in
  23 this case the next I/O operation might change the orientation (to byte
  24 oriented if it is a char I/O operation, or to wide-character oriented
  25 if it is a wide character I/O operation).
  26
  27 Once a stream has an orientation, it cannot be changed and persists
  28 until the stream is closed, unless the stream is re-opened with freopen,
  29 which removes the orientation of the stream.
  30
  31 When <[mode]> is non-zero, the <<fwide>> function first attempts to set
  32 <[fp]>'s orientation (to wide-character oriented if <[mode]> > 0, or to
  33 byte oriented if <[mode]> < 0). It then returns a value denoting the
  34 current orientation, as above.
  35
  36 RETURNS
  37 The <<fwide>> function returns <[fp]>'s orientation, after possibly
  38 changing it. A return value > 0 means wide-character oriented. A return
  39 value < 0 means byte oriented. A return value of zero means undecided.
  40
  41 PORTABILITY
  42 C99, POSIX.1-2001.
  43
  44 */
  45
  46 #include <_ansi.h>
  47 #include <wchar.h>
  48 #include "local.h"
  49
  50 int
  51 _fwide_r (struct _reent *ptr,
  52         FILE *fp,
  53         int mode)
  54 {
  55   int ret;
  56
  57   CHECK_INIT(ptr, fp);
  58
  59   _newlib_flockfile_start (fp);
  60   if (mode != 0) {
  61     (void) ORIENT (fp, mode);
  62   }
  63   if (!(fp->_flags & __SORD))
  64     ret = 0;
  65   else
  66     ret = (fp->_flags2 & __SWID) ? 1 : -1;
  67   _newlib_flockfile_end (fp);
  68   return ret;
  69 }
  70
  71 int
  72 fwide (FILE *fp,
  73         int mode)
  74 {
  75   return _fwide_r (_REENT, fp, mode);
  76 }