stdbuf.c revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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 * $FreeBSD: stable/11/lib/libstdbuf/stdbuf.c 330897 2018-03-14 03:19:51Z eadler $
29 */
30
31#include <err.h>
32#include <errno.h>
33#include <limits.h>
34#include <stdio.h>
35#include <stdlib.h>
36#include <string.h>
37
38static const char *
39stream_name(FILE *s)
40{
41
42	if (s == stdin)
43		return "stdin";
44	if (s == stdout)
45		return "stdout";
46	if (s == stderr)
47		return "stderr";
48	/* This should not happen. */
49	abort();
50}
51
52static void
53change_buf(FILE *s, const char *bufmode)
54{
55	char *unit;
56	size_t bufsize;
57	int mode;
58
59	bufsize = 0;
60	if (bufmode[0] == '0' && bufmode[1] == '\0')
61		mode = _IONBF;
62	else if (bufmode[0] == 'L' && bufmode[1] == '\0')
63		mode = _IOLBF;
64	else if (bufmode[0] == 'B' && bufmode[1] == '\0') {
65		mode = _IOFBF;
66		bufsize = 0;
67	} else {
68		/*
69		 * This library being preloaded, depending on libutil
70		 * would lead to excessive namespace pollution.
71		 * Thus we do not use expand_number().
72		 */
73		errno = 0;
74		bufsize = strtol(bufmode, &unit, 0);
75		if (errno == EINVAL || errno == ERANGE || unit == bufmode)
76			warn("Wrong buffer mode '%s' for %s", bufmode,
77			    stream_name(s));
78		switch (*unit) {
79		case 'G':
80			bufsize *= 1024 * 1024 * 1024;
81			break;
82		case 'M':
83			bufsize *= 1024 * 1024;
84			break;
85		case 'k':
86			bufsize *= 1024;
87			break;
88		case '\0':
89			break;
90		default:
91			warnx("Unknown suffix '%c' for %s", *unit,
92			    stream_name(s));
93			return;
94		}
95		mode = _IOFBF;
96	}
97	if (setvbuf(s, NULL, mode, bufsize) != 0)
98		warn("Cannot set buffer mode '%s' for %s", bufmode,
99		    stream_name(s));
100}
101
102__attribute__ ((constructor)) static void
103stdbuf(void)
104{
105	char *i_mode, *o_mode, *e_mode;
106
107	i_mode = getenv("_STDBUF_I");
108	o_mode = getenv("_STDBUF_O");
109	e_mode = getenv("_STDBUF_E");
110
111	if (e_mode != NULL)
112		change_buf(stderr, e_mode);
113	if (i_mode != NULL)
114		change_buf(stdin, i_mode);
115	if (o_mode != NULL)
116		change_buf(stdout, o_mode);
117}
118