jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2021, Ben Wiederhake <BenWiederhake.GitHub@gmx.de>
3 * Copyright (c) 2022, Eli Youngs <eli.m.youngs@gmail.com>
4 *
5 * SPDX-License-Identifier: BSD-2-Clause
6 */
7
8#include <AK/DeprecatedString.h>
9#include <AK/Random.h>
10#include <AK/Vector.h>
11#include <LibCore/ArgsParser.h>
12#include <LibCore/File.h>
13#include <LibCore/System.h>
14#include <LibMain/Main.h>
15
16ErrorOr<int> serenity_main(Main::Arguments arguments)
17{
18 TRY(Core::System::pledge("stdio rpath"));
19
20 Core::ArgsParser args_parser;
21 StringView path;
22 Optional<size_t> head_count;
23 bool is_zero_terminated = false;
24
25 args_parser.add_positional_argument(path, "File", "file", Core::ArgsParser::Required::No);
26 args_parser.add_option(head_count, "Output at most \"count\" lines", "head-count", 'n', "count");
27 args_parser.add_option(is_zero_terminated, "Split input on \\0, not newline", "zero-terminated", 'z');
28
29 args_parser.parse(arguments);
30
31 auto file = TRY(Core::File::open_file_or_standard_stream(path, Core::File::OpenMode::Read));
32 ByteBuffer buffer = TRY(file->read_until_eof());
33
34 u8 input_delimiter = is_zero_terminated ? '\0' : '\n';
35 Vector<Bytes> lines;
36
37 auto bytes = buffer.span();
38 size_t line_start = 0;
39 size_t line_length = 0;
40 for (size_t i = 0; i < bytes.size(); ++i) {
41 if (bytes[i] == input_delimiter) {
42 lines.append(bytes.slice(line_start, line_length));
43 line_start = i + 1;
44 line_length = 0;
45 } else {
46 ++line_length;
47 }
48 }
49 if (line_length > 0) {
50 lines.append(bytes.slice(line_start));
51 }
52
53 if (lines.is_empty())
54 return 0;
55
56 AK::shuffle(lines);
57
58 Array<u8, 1> output_delimiter = { '\n' };
59 for (size_t i = 0; i < min(head_count.value_or(lines.size()), lines.size()); ++i) {
60 TRY(Core::System::write(STDOUT_FILENO, lines.at(i)));
61 TRY(Core::System::write(STDOUT_FILENO, output_delimiter));
62 }
63
64 return 0;
65}