1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2012 Jeremie Le Hen <jlh@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <err.h>
30#include <errno.h>
31#include <limits.h>
32#include <stdio.h>
33#include <stdlib.h>
34#include <string.h>
35
36static const char *
37stream_name(FILE *s)
38{
39
40	if (s == stdin)
41		return "stdin";
42	if (s == stdout)
43		return "stdout";
44	if (s == stderr)
45		return "stderr";
46	/* This should not happen. */
47	abort();
48}
49
50static void
51change_buf(FILE *s, const char *bufmode)
52{
53	char *unit;
54	size_t bufsize;
55	int mode;
56
57	bufsize = 0;
58	if (bufmode[0] == '0' && bufmode[1] == '\0')
59		mode = _IONBF;
60	else if (bufmode[0] == 'L' && bufmode[1] == '\0')
61		mode = _IOLBF;
62	else if (bufmode[0] == 'B' && bufmode[1] == '\0') {
63		mode = _IOFBF;
64		bufsize = 0;
65	} else {
66		/*
67		 * This library being preloaded, depending on libutil
68		 * would lead to excessive namespace pollution.
69		 * Thus we do not use expand_number().
70		 */
71		errno = 0;
72		bufsize = strtol(bufmode, &unit, 0);
73		if (errno == EINVAL || errno == ERANGE || unit == bufmode)
74			warn("Wrong buffer mode '%s' for %s", bufmode,
75			    stream_name(s));
76		switch (*unit) {
77		case 'G':
78			bufsize *= 1024 * 1024 * 1024;
79			break;
80		case 'M':
81			bufsize *= 1024 * 1024;
82			break;
83		case 'k':
84			bufsize *= 1024;
85			break;
86		case '\0':
87			break;
88		default:
89			warnx("Unknown suffix '%c' for %s", *unit,
90			    stream_name(s));
91			return;
92		}
93		mode = _IOFBF;
94	}
95	if (setvbuf(s, NULL, mode, bufsize) != 0)
96		warn("Cannot set buffer mode '%s' for %s", bufmode,
97		    stream_name(s));
98}
99
100__attribute__ ((constructor)) static void
101stdbuf(void)
102{
103	char *i_mode, *o_mode, *e_mode;
104
105	i_mode = getenv("_STDBUF_I");
106	o_mode = getenv("_STDBUF_O");
107	e_mode = getenv("_STDBUF_E");
108
109	if (e_mode != NULL)
110		change_buf(stderr, e_mode);
111	if (i_mode != NULL)
112		change_buf(stdin, i_mode);
113	if (o_mode != NULL)
114		change_buf(stdout, o_mode);
115}
116