/* makebuf.c - make a file buffer. stdio.h *//* Copyright 1992 Wind River Systems, Inc. *//*modification history--------------------01b,20sep92,smb  documentation additions01a,29jul92,smb  taken from UCB stdio, removed fstat().*//*DESCRIPTION * 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. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright *    notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright *    notice, this list of conditions and the following disclaimer in the *    documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software *    must display the following acknowledgement: *	This product includes software developed by the University of *	California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors *    may be used to endorse or promote products derived from this software *    without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE.INCLUDE FILE: stdio.h, sys/types.h, sys/stat.h, unistd.h, stdlib.hSEE ALSO: American National Standard X3.159-1989NOMANUAL*/#include "vxWorks.h"#include "ioLib.h"#include "stdio.h"#include "sys/types.h"#include "sys/stat.h"#include "unistd.h"#include "stdlib.h"#include "private/stdioP.h"/******************************************************************************** __smakebuf - Allocate a file buffer, or switch to unbuffered I/O.** As a side effect, we set __SOPT or __SNPT (en/dis-able fseek* optimisation) right after the fstat() that finds the buffer size.* * INCLUDE: stdio.h ** RETURNS: * NOMANUAL*/void __smakebuf    (    FAST FILE *fp    )    {    FAST size_t	size;    FAST BOOL 	couldBeTty;    FAST void *	p;    struct stat st;    if (fp->_flags & __SNBF) 		/* is buffering disabled? */	{	fp->_bf._base	= fp->_nbuf;	/* base of single character buf */	fp->_p		= fp->_nbuf;	/* point to character buf */	fp->_bf._size	= 1;		/* length of buf is one */	return;				/* RETURN */	}    if (fp->_file < 0)			/* has fd been associated with file? */	{	couldBeTty  = FALSE;		/* can't be a tty */	size	    = BUFSIZ;		/* standard buffer size */	fp->_flags |= __SNPT;		/* don't optimize fseek() */	}     					/* get blksize hint from driver */    else if ((ioctl (fp->_file, FIOFSTATGET, (int)&st)) < 0)	{	couldBeTty  = TRUE;		/* tyLib does not support fstat! */	size	    = BUFSIZ;		/* standard buffer size */	fp->_flags |= __SNPT;		/* do not try to optimise fseek() */	}    else	{	couldBeTty = ((st.st_mode & S_IFMT) == S_IFCHR);	size = (st.st_blksize <= 0) ? (BUFSIZ) : (st.st_blksize);	/*	 * Optimise fseek() only if it is a regular file.	 * (The test for __sseek is mainly paranoia.)	 */	if ((st.st_mode & S_IFMT) == S_IFREG) 	    {	    fp->_flags	|= __SOPT;	    fp->_blksize = st.st_blksize;	    } 	else	    fp->_flags	|= __SNPT;	}    if ((p = malloc (size)) == NULL) 	/* if malloc fails, disable buffering */	{	fp->_flags	|= __SNBF;	fp->_bf._base	 = fp->_p = fp->_nbuf;	fp->_bf._size	 = 1;	}    else 	{	fp->_flags	|= __SMBF;	/* mark buffer as malloced to reclaim */	fp->_bf._base	 = fp->_p = p;	fp->_bf._size	 = size;	if (couldBeTty && isatty (fp->_file))		    fp->_flags	|= __SLBF;	/* turn on line buffering if tty */	}    }