new stdio

[unix-history] / usr / src / lib / libc / stdio / setvbuf.c

/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Chris Torek.
*
* %sccs.include.redist.c%
*/

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)setvbuf.c   5.1 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

#include <stdio.h>
#include <stdlib.h>
#include "local.h"

/*
* Set one of the three kinds of buffering, optionally including
* a buffer.
*/
setvbuf(fp, buf, mode, size)
       register FILE *fp;
       char *buf;
       register int mode;
       register size_t size;
{

       /*
        * Verify arguments.  The `int' limit on `size' is due to this
        * particular implementation.
        */
       if ((mode != _IOFBF && mode != _IOLBF && mode != _IONBF) ||
           (int)size < 0)
               return (EOF);

       /*
        * Write current buffer, if any; drop read count, if any.
        * Make sure putc() will not think fp is line buffered.
        * Free old buffer if it was from malloc().  Clear line and
        * non buffer flags, and clear malloc flag.
        */
       (void) fflush(fp);
       fp->_r = 0;
       fp->_lbfsize = 0;
       if (fp->_flags & __SMBF)
               free((void *)fp->_bf._base);
       fp->_flags &= ~(__SLBF|__SNBF|__SMBF);

       /*
        * Now put back whichever flag is needed, and fix _lbfsize
        * if line buffered.  Ensure output flush on exit if the
        * stream will be buffered at all.
        */
       switch (mode) {

       case _IONBF:
               fp->_flags |= __SNBF;
               fp->_bf._base = fp->_p = fp->_nbuf;
               fp->_bf._size = 1;
               break;

       case _IOLBF:
               fp->_flags |= __SLBF;
               fp->_lbfsize = -size;
               /* FALLTHROUGH */

       case _IOFBF:
               /* no flag */
               __cleanup = _cleanup;
               fp->_bf._base = fp->_p = (unsigned char *)buf;
               fp->_bf._size = size;
               break;
       }

       /*
        * Patch up write count if necessary.
        */
       if (fp->_flags & __SWR)
               fp->_w = fp->_flags & (__SLBF|__SNBF) ? 0 : size;

       return (0);
}