1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include "namespace.h"
36#include <sys/types.h>
37#include <sys/stat.h>
38#include <unistd.h>
39#include <stdio.h>
40#include <stdlib.h>
41#include "un-namespace.h"
42
43#include "libc_private.h"
44#include "local.h"
45
46/*
47 * Allocate a file buffer, or switch to unbuffered I/O.
48 * Per the ANSI C standard, ALL tty devices default to line buffered.
49 *
50 * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
51 * optimisation) right after the _fstat() that finds the buffer size.
52 */
53void
54__smakebuf(FILE *fp)
55{
56	void *p;
57	int flags;
58	size_t size;
59	int couldbetty;
60
61	if (fp->_flags & __SNBF) {
62		fp->_bf._base = fp->_p = fp->_nbuf;
63		fp->_bf._size = 1;
64		return;
65	}
66	flags = __swhatbuf(fp, &size, &couldbetty);
67	if ((p = malloc(size)) == NULL) {
68		fp->_flags |= __SNBF;
69		fp->_bf._base = fp->_p = fp->_nbuf;
70		fp->_bf._size = 1;
71		return;
72	}
73	__cleanup = _cleanup;
74	flags |= __SMBF;
75	fp->_bf._base = fp->_p = p;
76	fp->_bf._size = size;
77	if (couldbetty && isatty(fp->_file))
78		flags |= __SLBF;
79	fp->_flags |= flags;
80}
81
82/*
83 * Internal routine to determine `proper' buffering for a file.
84 */
85int
86__swhatbuf(FILE *fp, size_t *bufsize, int *couldbetty)
87{
88	struct stat st;
89
90	if (fp->_file < 0 || _fstat(fp->_file, &st) < 0) {
91		*couldbetty = 0;
92		*bufsize = BUFSIZ;
93		return (__SNPT);
94	}
95
96	/* could be a tty iff it is a character device */
97	*couldbetty = (st.st_mode & S_IFMT) == S_IFCHR;
98	if (st.st_blksize <= 0) {
99		*bufsize = BUFSIZ;
100		return (__SNPT);
101	}
102
103	/*
104	 * Optimise fseek() only if it is a regular file.  (The test for
105	 * __sseek is mainly paranoia.)  It is safe to set _blksize
106	 * unconditionally; it will only be used if __SOPT is also set.
107	 */
108	*bufsize = st.st_blksize;
109	fp->_blksize = st.st_blksize;
110	return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ?
111	    __SOPT : __SNPT);
112}
113