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/* $OpenBSD: makebuf.c,v 1.9 2015/01/13 07:18:21 guenther 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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✓✓ |
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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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✗✓ |
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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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flags |= __SMBF; |
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fp->_bf._base = fp->_p = p; |
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fp->_bf._size = size; |
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✓✓✓✗
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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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✓✗✗✓
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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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✗✓ |
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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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✓✓ |
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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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} |