windows-xp/Source/XPSP1/NT/base/crts/crtw32/stdio/_filbuf.c

/***
*_filbuf.c - fill buffer and get character
*
*       Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       defines _filbuf() - fill buffer and read first character, allocate
*       buffer if there is none.  Used from getc().
*       defines _filwbuf() - fill buffer and read first wide character, allocate
*       buffer if there is none.  Used from getwc().
*
*Revision History:
*       09-01-83  RN    initial version
*       06-26-85  TC    added code to handle variable length buffers
*       04-16-87  JCR   added _IOUNGETC support
*       08-04-87  JCR   added _getbuff routine
*       09-28-87  JCR   Corrected _iob2 indexing (now uses _iob_index() macro).
*       11-06-87  JCR   Multi-thread support; also, split _getbuf() off
*       12-11-87  JCR   Added "_LOAD_DS" to declaration
*       01-11-88  JCR   Merged mthread version into normal code
*       01-13-88  SKS   Changed bogus "_fileno_lk" to "fileno"
*       03-04-88  JCR   Read() return value must be considered unsigned, not
*                       signed
*       06-06-88  JCR   Optimized _iob2 references
*       06-13-88  JCR   Use near pointer to reference _iob[] entries
*       08-25-88  GJF   Don't use FP_OFF() macro for the 386
*       06-20-89  PHG   Re-activate C version, propogated fixes
*       08-28-89  JCR   Removed _NEAR_ for 386
*       02-15-90  GJF   _iob[], _iob2[] merge. Also, fixed copyright and
*                       alignment.
*       03-16-90  GJF   Replaced cdecl _LOAD_DS with _CALLTYPE1, added #include
*                       <cruntime.h> and removed #include <register.h>. Also,
*                       removed some leftover 16-bit support.
*       03-27-90  GJF   Added #include <io.h>.
*       07-23-90  SBM   Replaced <assertm.h> by <assert.h>
*       10-03-90  GJF   New-style function declarator.
*       01-22-91  GJF   ANSI naming.
*       03-27-92  DJM   POSIX support.
*       08-26-92  GJF   Include unistd.h for POSIX build.
*       04-06-93  SKS   Replace _CRTAPI* with __cdecl
*       04-26-93  CFW   Wide char enable.
*       05-06-93  CFW   Optimize wide char conversion.
*       05-24-93  GJF   Detect small buffer size (_SMALL_BUFSIZ) resulting
*                       from fseek call on read-access-only stream and
*                       restore the larger size (_INTERNAL_BUFSIZ) for the
*                       next _filbuf call.
*       06-22-93  GJF   Check _IOSETVBUF (new) before changing buffer size.
*       11-05-93  GJF   Merged with NT SDK version (picked up _NTSUBSET_
*                       stuff).
*       10-17-94  BWT   Move wchar.h to non-POSIX build (ino_t definitions conflict)
*       02-06-94  CFW   assert -> _ASSERTE.
*       02-16-95  GJF   Appended Mac version of source file (somewhat cleaned
*                       up), with appropriate #ifdef-s.
*       06-12-95  GJF   Replaced _osfile[] with _osfile() (macro referencing
*                       field in ioinfo struct).
*       07-27-95  GJF   Replaced _osfile() with _osfile_safe().
*       12-07-95  SKS   Fix misspelling of _NTSUBSET_ (final _ was missing)
*       05-17-99  PML   Remove all Macintosh support.
*
*******************************************************************************/

#include <cruntime.h>
#include <stdio.h>
#include <file2.h>
#include <io.h>
#include <dbgint.h>
#include <malloc.h>
#include <internal.h>
#ifdef  _POSIX_
#include <unistd.h>
#include <errno.h>
#else
#include <msdos.h>
#include <wchar.h>
#endif
#ifdef  _MT
#include <mtdll.h>
#endif
#include <tchar.h>

#ifndef _UNICODE

/***
*int _filbuf(stream) - fill buffer and get first character
*
*Purpose:
*       get a buffer if the file doesn't have one, read into it, return first
*       char. try to get a buffer, if a user buffer is not assigned. called
*       only from getc; intended for use only within library. assume no input
*       stream is to remain unbuffered when memory is available unless it is
*       marked _IONBF. at worst, give it a single char buffer. the need for a
*       buffer, no matter how small, becomes evident when we consider the
*       ungetc's necessary in scanf
*
*       [NOTE: Multi-thread - _filbuf() assumes that the caller has aquired
*       the stream lock, if needed.]
*
*Entry:
*       FILE *stream - stream to read from
*
*Exit:
*       returns first character from buffer (next character to be read)
*       returns EOF if the FILE is actually a string, or not open for reading,
*       or if open for writing or if no more chars to read.
*       all fields in FILE structure may be changed except _file.
*
*Exceptions:
*
*******************************************************************************/

int __cdecl _filbuf (
        FILE *str
        )

#else  /* _UNICODE */

/***
*int _filwbuf(stream) - fill buffer and get first wide character
*
*Purpose:
*       get a buffer if the file doesn't have one, read into it, return first
*       char. try to get a buffer, if a user buffer is not assigned. called
*       only from getc; intended for use only within library. assume no input
*       stream is to remain unbuffered when memory is available unless it is
*       marked _IONBF. at worst, give it a single char buffer. the need for a
*       buffer, no matter how small, becomes evident when we consider the
*       ungetc's necessary in scanf
*
*       [NOTE: Multi-thread - _filwbuf() assumes that the caller has aquired
*       the stream lock, if needed.]
*
*Entry:
*       FILE *stream - stream to read from
*
*Exit:
*       returns first wide character from buffer (next character to be read)
*       returns WEOF if the FILE is actually a string, or not open for reading,
*       or if open for writing or if no more chars to read.
*       all fields in FILE structure may be changed except _file.
*
*Exceptions:
*
*******************************************************************************/

int __cdecl _filwbuf (
        FILE *str
        )

#endif  /* _UNICODE */

{
#ifdef  _NTSUBSET_

        return(_TEOF);

#else   /* ndef _NTSUBSET_ */

        REG1 FILE *stream;

        _ASSERTE(str != NULL);

        /* Init pointer to _iob2 entry. */
        stream = str;

        if (!inuse(stream) || stream->_flag & _IOSTRG)
                return(_TEOF);

        if (stream->_flag & _IOWRT) {
#ifdef  _POSIX_
                errno = EBADF;
#endif
                stream->_flag |= _IOERR;
                return(_TEOF);
        }

        stream->_flag |= _IOREAD;

        /* Get a buffer, if necessary. */

        if (!anybuf(stream))
                _getbuf(stream);
        else
                stream->_ptr = stream->_base;

#ifdef  _POSIX_
        stream->_cnt = read(fileno(stream), stream->_base, stream->_bufsiz);
#else
        stream->_cnt = _read(_fileno(stream), stream->_base, stream->_bufsiz);
#endif

#ifndef _UNICODE
        if ((stream->_cnt == 0) || (stream->_cnt == -1)) {
#else /* _UNICODE */
        if ((stream->_cnt == 0) || (stream->_cnt == 1) || stream->_cnt == -1) {
#endif /* _UNICODE */
                stream->_flag |= stream->_cnt ? _IOERR : _IOEOF;
                stream->_cnt = 0;
                return(_TEOF);
        }

#ifndef _POSIX_
        if (  !(stream->_flag & (_IOWRT|_IORW)) &&
              ((_osfile_safe(_fileno(stream)) & (FTEXT|FEOFLAG)) == 
                (FTEXT|FEOFLAG)) )
                stream->_flag |= _IOCTRLZ;
#endif
        /* Check for small _bufsiz (_SMALL_BUFSIZ). If it is small and
           if it is our buffer, then this must be the first _filbuf after
           an fseek on a read-access-only stream. Restore _bufsiz to its
           larger value (_INTERNAL_BUFSIZ) so that the next _filbuf call,
           if one is made, will fill the whole buffer. */
        if ( (stream->_bufsiz == _SMALL_BUFSIZ) && (stream->_flag &
              _IOMYBUF) && !(stream->_flag & _IOSETVBUF) )
        {
                stream->_bufsiz = _INTERNAL_BUFSIZ;
        }
#ifndef _UNICODE
        stream->_cnt--;
        return(0xff & *stream->_ptr++);
#else   /* _UNICODE */
        stream->_cnt -= sizeof(wchar_t);
        return (0xffff & *((wchar_t *)(stream->_ptr))++);
#endif  /* _UNICODE */

#endif  /* _NTSUBSET_ */
}