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Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice, this
9 * list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <AK/String.h>
28#include <AK/StringBuilder.h>
29#include <AK/Vector.h>
30#include <LibCore/ArgsParser.h>
31#include <LibCore/DirIterator.h>
32#include <LibCore/File.h>
33#include <dirent.h>
34#include <errno.h>
35#include <fcntl.h>
36#include <stdio.h>
37#include <string.h>
38#include <unistd.h>
39
40static String read_var(const String& name)
41{
42 StringBuilder builder;
43 builder.append("/proc/sys/");
44 builder.append(name);
45 auto path = builder.to_string();
46 auto f = Core::File::construct(path);
47 if (!f->open(Core::IODevice::ReadOnly)) {
48 fprintf(stderr, "open: %s", f->error_string());
49 exit(1);
50 }
51 const auto& b = f->read_all();
52 if (f->error() < 0) {
53 fprintf(stderr, "read: %s", f->error_string());
54 exit(1);
55 }
56 return String((const char*)b.data(), b.size(), Chomp);
57}
58
59static void write_var(const String& name, const String& value)
60{
61 StringBuilder builder;
62 builder.append("/proc/sys/");
63 builder.append(name);
64 auto path = builder.to_string();
65 auto f = Core::File::construct(path);
66 if (!f->open(Core::IODevice::WriteOnly)) {
67 fprintf(stderr, "open: %s", f->error_string());
68 exit(1);
69 }
70 f->write(value);
71 if (f->error() < 0) {
72 fprintf(stderr, "write: %s", f->error_string());
73 exit(1);
74 }
75}
76
77static int handle_show_all()
78{
79 Core::DirIterator di("/proc/sys", Core::DirIterator::SkipDots);
80 if (di.has_error()) {
81 fprintf(stderr, "CDirIterator: %s\n", di.error_string());
82 return 1;
83 }
84
85 while (di.has_next()) {
86 String variable_name = di.next_path();
87 printf("%s = %s\n", variable_name.characters(), read_var(variable_name).characters());
88 }
89 return 0;
90}
91
92static int handle_var(const String& var)
93{
94 String spec(var.characters(), Chomp);
95 auto parts = spec.split('=');
96 String variable_name = parts[0];
97 bool is_write = parts.size() > 1;
98
99 if (!is_write) {
100 printf("%s = %s\n", variable_name.characters(), read_var(variable_name).characters());
101 return 0;
102 }
103
104 printf("%s = %s", variable_name.characters(), read_var(variable_name).characters());
105 write_var(variable_name, parts[1]);
106 printf(" -> %s\n", read_var(variable_name).characters());
107 return 0;
108}
109
110int main(int argc, char** argv)
111{
112 bool show_all = false;
113 const char* var = nullptr;
114
115 Core::ArgsParser args_parser;
116 args_parser.add_option(show_all, "Show all variables", nullptr, 'a');
117 args_parser.add_positional_argument(var, "Command (var[=value])", "command");
118 args_parser.parse(argc, argv);
119
120 if (show_all) {
121 return handle_show_all();
122 }
123
124 return handle_var(var);
125}