108 lines
3.4 KiB
C
108 lines
3.4 KiB
C
/* $OpenBSD: makebuf.c,v 1.8 2005/12/28 18:50:22 millert Exp $ */
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/*-
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. 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. 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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*/
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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 <stdio.h>
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#include <stdlib.h>
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#include "local.h"
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/*
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* Allocate a file buffer, or switch to unbuffered I/O.
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* Per the ANSI C standard, ALL tty devices default to line buffered.
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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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void
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__smakebuf(FILE *fp)
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{
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void *p;
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int flags;
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size_t size;
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int couldbetty;
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if (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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return;
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}
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flags = __swhatbuf(fp, &size, &couldbetty);
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if ((p = malloc(size)) == NULL) {
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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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return;
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}
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__atexit_register_cleanup(_cleanup);
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flags |= __SMBF;
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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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flags |= __SLBF;
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fp->_flags |= flags;
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}
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/*
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* Internal routine to determine `proper' buffering for a file.
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*/
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int
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__swhatbuf(FILE *fp, size_t *bufsize, int *couldbetty)
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{
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struct stat st;
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if (fp->_file < 0 || fstat(fp->_file, &st) < 0) {
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*couldbetty = 0;
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*bufsize = BUFSIZ;
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return (__SNPT);
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}
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/* could be a tty iff it is a character device */
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*couldbetty = S_ISCHR(st.st_mode);
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if (st.st_blksize == 0) {
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*bufsize = BUFSIZ;
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return (__SNPT);
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}
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/*
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* Optimise fseek() only if it is a regular file. (The test for
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* __sseek is mainly paranoia.) It is safe to set _blksize
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* unconditionally; it will only be used if __SOPT is also set.
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*/
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*bufsize = st.st_blksize;
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fp->_blksize = st.st_blksize;
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return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ?
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__SOPT : __SNPT);
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}
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