libc/stdio/_trans2w.c

   1 /* Copyright (C) 2004       Manuel Novoa III    <[email protected]>
   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 writing.
  11  *   Initialize or verify the stream's orientation (even if readonly).
  12  *   Check that the stream is writable.
  13  *   If currently reading, check that we can transition to writing.
  14  *      C99 requires that the stream is at EOF, but attempting to
  15  *      auto-transition via fseek() is a configurable option.
  16  *   Returns 0 on success and EOF otherwise.
  17  *
  18  * Notes:
  19  *   There are two function signatures, depending on wchar support,
  20  *   since with no wchar support the orientation is narrow by default.
  21  */
  22
  23 #ifdef __UCLIBC_HAS_WCHAR__
  24 int __stdio_trans2w_o(FILE * __restrict stream, int oflag)
  25 #else
  26 int __stdio_trans2w(FILE * __restrict stream)
  27 #endif
  28 {
  29         __STDIO_STREAM_VALIDATE(stream);
  30         assert(!__STDIO_STREAM_IS_WRITING(stream));
  31
  32 #ifdef __UCLIBC_HAS_WCHAR__
  33         if (!(stream->__modeflags & oflag)) {
  34                 if (stream->__modeflags & (__FLAG_NARROW|__FLAG_WIDE)) {
  35                         __UNDEFINED_OR_NONPORTABLE;
  36                         goto DO_EBADF;
  37                 }
  38                 stream->__modeflags |= oflag;
  39         }
  40 #endif
  41
  42         if (stream->__modeflags & __FLAG_READONLY) {
  43 #if defined(__UCLIBC_HAS_WCHAR__) || !defined(__UCLIBC_HAS_STDIO_AUTO_RW_TRANSITION__)
  44         DO_EBADF:
  45 #endif
  46                 __set_errno(EBADF);
  47 #ifdef __UCLIBC_HAS_STDIO_AUTO_RW_TRANSITION__
  48         ERROR:
  49 #endif
  50                 __STDIO_STREAM_SET_ERROR(stream);
  51                 __STDIO_STREAM_VALIDATE(stream);
  52                 return EOF;
  53         }
  54
  55         if (__STDIO_STREAM_IS_READING(stream)) {
  56                 if (!__FEOF_UNLOCKED(stream)) {
  57 #ifdef __UCLIBC_HAS_STDIO_AUTO_RW_TRANSITION__
  58                         /* Need to seek to correct position if we have buffered
  59                          * read data or ungots.  If appending, we might as well
  60                          * seek to the end.
  61                          *
  62                          * NOTE: If the OS does not handle append files correctly,
  63                          *   this is insufficient since we would need to seek to
  64                          *   the end even if not reading.*/
  65                         if (((__STDIO_STREAM_BUFFER_RAVAIL(stream))
  66                                  || (stream->__modeflags & __FLAG_UNGOT))
  67                                 && fseek(stream, 0L,
  68                                                  ((stream->__modeflags & __FLAG_APPEND)
  69                                                   ? SEEK_END : SEEK_CUR))
  70                                 ) {
  71                                 /* fseek() only sets error indicator on read/write error. */
  72                                 goto ERROR;
  73                         }
  74 #else
  75                         /* C99 requires either at EOF or currently not reading. */
  76                         __UNDEFINED_OR_NONPORTABLE;
  77                         goto DO_EBADF;
  78 #endif
  79                 }
  80                 __STDIO_STREAM_CLEAR_READING_AND_UNGOTS(stream);
  81                 __STDIO_STREAM_DISABLE_GETC(stream);
  82                 /* Reaching EOF does not reset buffer pointers... */
  83                 __STDIO_STREAM_INIT_BUFREAD_BUFPOS(stream);
  84         }
  85
  86         __STDIO_STREAM_SET_WRITING(stream);
  87         if (__STDIO_STREAM_IS_NARROW_FBF(stream)) {
  88                 __STDIO_STREAM_ENABLE_PUTC(stream);
  89         }
  90
  91         __STDIO_STREAM_VALIDATE(stream);
  92         return 0;
  93 }