libc/stdio/_trans2r.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 /* Function to handle transition to reading.
  11  *   Initialize or verify the stream's orientation (even if writeonly).
  12  *   Check that the stream is readable.
  13  *   If currently reading, check that we can transition to writing.
  14  *      C99 requires that we not be reading, but attempting to
  15  *      auto-transition by commiting the write buffer is a configurable
  16  *      option.
  17  *   Returns 0 on success and EOF otherwise.
  18  *
  19  * Notes:
  20  *   There are two function signatures, depending on wchar support,
  21  *   since with no wchar support the orientation is narrow by default.
  22  */
  23
  24 #ifdef __UCLIBC_HAS_WCHAR__
  25 int attribute_hidden __stdio_trans2r_o(FILE * __restrict stream, int oflag)
  26 #else
  27 int attribute_hidden __stdio_trans2r(FILE * __restrict stream)
  28 #endif
  29 {
  30         __STDIO_STREAM_VALIDATE(stream);
  31         assert(!__STDIO_STREAM_IS_READING(stream));
  32
  33 #ifdef __UCLIBC_HAS_WCHAR__
  34         if (!(stream->__modeflags & oflag)) {
  35                 if (stream->__modeflags & (__FLAG_NARROW|__FLAG_WIDE)) {
  36                         __UNDEFINED_OR_NONPORTABLE;
  37                         goto DO_EBADF;
  38                 }
  39                 stream->__modeflags |= oflag;
  40         }
  41 #endif
  42
  43         if (stream->__modeflags & __FLAG_WRITEONLY) {
  44 #if defined(__UCLIBC_HAS_WCHAR__) || !defined(__UCLIBC_HAS_STDIO_AUTO_RW_TRANSITION__)
  45         DO_EBADF:
  46 #endif
  47                 __set_errno(EBADF);
  48 #ifdef __UCLIBC_HAS_STDIO_AUTO_RW_TRANSITION__
  49         ERROR:
  50 #endif
  51                 __STDIO_STREAM_SET_ERROR(stream);
  52                 __STDIO_STREAM_VALIDATE(stream);
  53                 return EOF;
  54         }
  55
  56         if (__STDIO_STREAM_IS_WRITING(stream)) {
  57 #ifdef __UCLIBC_HAS_STDIO_AUTO_RW_TRANSITION__
  58                 if (__STDIO_COMMIT_WRITE_BUFFER(stream)) { /* commit failed! */
  59                         goto ERROR;
  60                 }
  61                 assert(!__STDIO_STREAM_BUFFER_WUSED(stream));
  62
  63                 __STDIO_STREAM_DISABLE_PUTC(stream);
  64                 __STDIO_STREAM_CLEAR_WRITING(stream);
  65 #else
  66                 /* C99: Output shall not be directly followed by input without an
  67                    intervening call to the fflush function or to a file positioning
  68                    function (fseek, fsetpos, or rewind). */
  69                 __UNDEFINED_OR_NONPORTABLE;
  70                 goto DO_EBADF;
  71 #endif
  72         }
  73
  74         __STDIO_STREAM_SET_READING(stream);
  75         /* getc macro is enabled when data is read into buffer. */
  76
  77         __STDIO_STREAM_VALIDATE(stream);
  78         return 0;
  79 }