145 lines
4.4 KiB
C
145 lines
4.4 KiB
C
/* makebuf.c - make a file buffer. stdio.h */
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/* Copyright 1992 Wind River Systems, Inc. */
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/*
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modification history
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--------------------
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01b,20sep92,smb documentation additions
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01a,29jul92,smb taken from UCB stdio, removed fstat().
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*/
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/*
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DESCRIPTION
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Chris Torek.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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INCLUDE FILE: stdio.h, sys/types.h, sys/stat.h, unistd.h, stdlib.h
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SEE ALSO: American National Standard X3.159-1989
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NOMANUAL
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*/
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#include "vxWorks.h"
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#include "ioLib.h"
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#include "stdio.h"
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#include "sys/types.h"
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#include "sys/stat.h"
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#include "unistd.h"
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#include "stdlib.h"
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#include "private/stdioP.h"
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/******************************************************************************
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*
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* __smakebuf - Allocate a file buffer, or switch to unbuffered I/O.
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*
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* As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
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* optimisation) right after the fstat() that finds the buffer size.
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*
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* INCLUDE: stdio.h
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*
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* RETURNS:
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* NOMANUAL
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*/
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void __smakebuf
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(
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FAST FILE *fp
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)
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{
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FAST size_t size;
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FAST BOOL couldBeTty;
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FAST void * p;
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struct stat st;
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if (fp->_flags & __SNBF) /* is buffering disabled? */
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{
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fp->_bf._base = fp->_nbuf; /* base of single character buf */
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fp->_p = fp->_nbuf; /* point to character buf */
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fp->_bf._size = 1; /* length of buf is one */
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return; /* RETURN */
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}
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if (fp->_file < 0) /* has fd been associated with file? */
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{
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couldBeTty = FALSE; /* can't be a tty */
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size = BUFSIZ; /* standard buffer size */
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fp->_flags |= __SNPT; /* don't optimize fseek() */
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}
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/* get blksize hint from driver */
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else if ((ioctl (fp->_file, FIOFSTATGET, (int)&st)) < 0)
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{
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couldBeTty = TRUE; /* tyLib does not support fstat! */
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size = BUFSIZ; /* standard buffer size */
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fp->_flags |= __SNPT; /* do not try to optimise fseek() */
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}
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else
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{
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couldBeTty = ((st.st_mode & S_IFMT) == S_IFCHR);
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size = (st.st_blksize <= 0) ? (BUFSIZ) : (st.st_blksize);
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/*
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* Optimise fseek() only if it is a regular file.
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* (The test for __sseek is mainly paranoia.)
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*/
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if ((st.st_mode & S_IFMT) == S_IFREG)
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{
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fp->_flags |= __SOPT;
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fp->_blksize = st.st_blksize;
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}
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else
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fp->_flags |= __SNPT;
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}
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if ((p = malloc (size)) == NULL) /* if malloc fails, disable buffering */
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{
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fp->_flags |= __SNBF;
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fp->_bf._base = fp->_p = fp->_nbuf;
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fp->_bf._size = 1;
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}
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else
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{
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fp->_flags |= __SMBF; /* mark buffer as malloced to reclaim */
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fp->_bf._base = fp->_p = p;
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fp->_bf._size = size;
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if (couldBeTty && isatty (fp->_file))
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fp->_flags |= __SLBF; /* turn on line buffering if tty */
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}
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}
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