_getbuf.c

C语言库函数的原型,有用的拿去

/***
*_getbuf.c - Get a stream buffer
*
*       Copyright (c) Microsoft Corporation. All rights reserved.
*
*Purpose:
*       Allocate a buffer and init stream data bases.
*
*******************************************************************************/

#include <cruntime.h>
#include <stdio.h>
#include <file2.h>
#include <malloc.h>
#include <internal.h>
#include <dbgint.h>

/***
*_getbuf() - Allocate a buffer and init stream data bases
*
*Purpose:
*       Allocates a buffer for a stream and inits the stream data bases.
*
*       [NOTE  1: This routine assumes the caller has already checked to make
*       sure the stream needs a buffer.
*
*       [NOTE 2: Multi-thread - Assumes caller has aquired stream lock, if
*       needed.]
*
*Entry:
*       FILE *stream = stream to allocate a buffer for
*
*Exit:
*       void
*
*Exceptions:
*
*******************************************************************************/

void __cdecl _getbuf (
        FILE *str
        )
{
        REG1 FILE *stream;

        _ASSERTE(str != NULL);

#if !defined (CRTDLL)
        /* force library pre-termination procedure */
        _cflush++;
#endif  /* !defined (CRTDLL) */

        /* Init pointers */
        stream = str;


        /* Try to get a big buffer */
        if (stream->_base = _malloc_crt(_INTERNAL_BUFSIZ))
        {
                /* Got a big buffer */
                stream->_flag |= _IOMYBUF;
                stream->_bufsiz = _INTERNAL_BUFSIZ;
        }

        else {


                /* Did NOT get a buffer - use single char buffering. */
                stream->_flag |= _IONBF;
                stream->_base = (char *)&(stream->_charbuf);
                stream->_bufsiz = 2;

        }

        stream->_ptr = stream->_base;
        stream->_cnt = 0;

        return;
}