libc/stdio/ungetwc.c

   1 /* Copyright (C) 2004       Manuel Novoa III    <mjn3@codepoet.org>
   2  *
   3  * GNU Library General Public License (LGPL) version 2 or later.
   4  *
   5  * Dedicated to Toni.  See uClibc/DEDICATION.mjn3 for details.
   6  */
   7
   8 #include "_stdio.h"
   9
  10 /* Note: This is the application-callable ungetwc.  If wscanf calls this, it
  11  * should also set stream->__ungot[1] to 0 if this is the only ungot, as well
  12  * as reset stream->__ungot_width[1] for use by _stdio_adjpos().
  13  */
  14
  15 wint_t ungetwc(wint_t c, register FILE *stream)
  16 {
  17         __STDIO_AUTO_THREADLOCK_VAR;
  18
  19         __STDIO_AUTO_THREADLOCK(stream);
  20         __STDIO_STREAM_VALIDATE(stream); /* debugging only */
  21
  22         /* Note: Even if c == WEOF, we need to initialize/verify the
  23          * stream's orientation and ensure the stream is in reading
  24          * mode (if readable and properly oriented). */
  25         if ((!__STDIO_STREAM_IS_WIDE_READING(stream)
  26                  && __STDIO_STREAM_TRANS_TO_READ(stream, __FLAG_WIDE))
  27                 || ((stream->__modeflags & __FLAG_UNGOT)
  28                         && ((stream->__modeflags & 1) || stream->__ungot[1]))
  29                 || (c == WEOF)
  30                 ) {
  31                 c = WEOF;
  32         } else {
  33                 /* In the wide case, getc macros should already be disabled. */
  34                 /*      __STDIO_STREAM_DISABLE_GETC(stream); */
  35
  36                 /* Flag this as a user ungot, as scanf does the necessary fixup. */
  37                 stream->__ungot[1] = 1;
  38                 stream->__ungot[(++stream->__modeflags) & 1] = c;
  39                 /* Note: ungot_width is handled by fgetwc. */
  40
  41                 __STDIO_STREAM_CLEAR_EOF(stream); /* Must clear end-of-file flag. */
  42         }
  43
  44         __STDIO_STREAM_VALIDATE(stream);
  45         __STDIO_AUTO_THREADUNLOCK(stream);
  46
  47         return c;
  48 }
  49 libc_hidden_def(ungetwc)