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This is a LibC function that POSIX defines to help userspace programs to get suboptions. An example of a suboption is the token "pixclk" from a Shell command running "edid-decode --gtf w=1024,h=768,pixclk=48". The function should be run in a while loop to acquire all suboptions until the last one.
51 lines
1.7 KiB
C++
51 lines
1.7 KiB
C++
/*
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* Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/ScopeGuard.h>
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#include <AK/StringView.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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// https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsubopt.html
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int getsubopt(char** option_array, char* const* tokens, char** option_value)
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{
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if (**option_array == '\0')
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return -1;
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auto option_string = StringView(*option_array);
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auto possible_comma_location = option_string.find(',');
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char* option_end = const_cast<char*>(option_string.characters_without_null_termination()) + possible_comma_location.value_or(option_string.length());
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auto possible_equals_char_location = option_string.find('=');
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char* value_start = option_end;
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if (possible_equals_char_location.has_value()) {
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value_start = const_cast<char*>(option_string.characters_without_null_termination()) + possible_equals_char_location.value();
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}
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ScopeGuard ensure_end_array_contains_null_char([&]() {
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if (*option_end != '\0')
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*option_end++ = '\0';
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*option_array = option_end;
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});
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for (int count = 0; tokens[count] != NULL; ++count) {
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auto token_stringview = StringView(tokens[count]);
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if (!option_string.starts_with(token_stringview))
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continue;
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if (tokens[count][value_start - *option_array] != '\0')
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continue;
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*option_value = value_start != option_end ? value_start + 1 : nullptr;
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return count;
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}
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// Note: The current sub-option does not match any option, so prepare to tell this
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// to the application.
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*option_value = *option_array;
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return -1;
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}
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