jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <AK/ScopeGuard.h>
8#include <AK/StringView.h>
9#include <string.h>
10#include <unistd.h>
11
12// https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsubopt.html
13int getsubopt(char** option_array, char* const* tokens, char** option_value)
14{
15 if (**option_array == '\0')
16 return -1;
17
18 auto const* option_ptr = *option_array;
19 StringView option_string { option_ptr, strlen(option_ptr) };
20
21 auto possible_comma_location = option_string.find(',');
22 char* option_end = const_cast<char*>(option_string.characters_without_null_termination()) + possible_comma_location.value_or(option_string.length());
23
24 auto possible_equals_char_location = option_string.find('=');
25 char* value_start = option_end;
26 if (possible_equals_char_location.has_value()) {
27 value_start = const_cast<char*>(option_string.characters_without_null_termination()) + possible_equals_char_location.value();
28 }
29
30 ScopeGuard ensure_end_array_contains_null_char([&]() {
31 if (*option_end != '\0')
32 *option_end++ = '\0';
33 *option_array = option_end;
34 });
35
36 for (int count = 0; tokens[count] != NULL; ++count) {
37 auto const* token = tokens[count];
38 StringView token_stringview { token, strlen(token) };
39 if (!option_string.starts_with(token_stringview))
40 continue;
41 if (tokens[count][value_start - *option_array] != '\0')
42 continue;
43
44 *option_value = value_start != option_end ? value_start + 1 : nullptr;
45 return count;
46 }
47
48 // Note: The current sub-option does not match any option, so prepare to tell this
49 // to the application.
50 *option_value = *option_array;
51 return -1;
52}