82 lines
2.4 KiB
C
82 lines
2.4 KiB
C
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#include <algorithm>
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#include <iostream>
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#include <fstream>
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#include <vector>
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#include <tuple>
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std::string loadFileAsLine(const std::string& path) {
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std::string result;
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std::ifstream file(path);
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if (file) {
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std::getline(file, result, '\n');
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} else {
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std::cerr << "Unable to read file " << path << std::endl;
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exit(EXIT_FAILURE);
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}
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return result;
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}
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void split (const std::string& str, std::vector<std::string>& result, const std::string& delimiters)
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{
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// from http://oopweb.com/CPP/Documents/CPPHOWTO/Volume/C++Programming-HOWTO-7.html
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// Skip delimiters at beginning.
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std::string::size_type lastPos = str.find_first_not_of (delimiters, 0);
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// Find first "non-delimiter".
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std::string::size_type pos = str.find_first_of (delimiters, lastPos);
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while (std::string::npos != pos || std::string::npos != lastPos) {
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// Found a token, add it to the vector.
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result.push_back (str.substr (lastPos, pos - lastPos));
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// Skip delimiters. Note the "not_of"
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lastPos = str.find_first_not_of (delimiters, pos);
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// Find next "non-delimiter"
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pos = str.find_first_of (delimiters, lastPos);
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}
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}
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// get value of key-value kernel command line argument
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// examples:
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// 1) f('mac') --> {true, '10:27:be:08:00:37'} if 'mac=10:27:be:08:00:37' is passed to kernel command line
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// 2) f('bullshit') --> {false, ''} if 'bullshit' is not passed to kernel command line
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std::tuple<bool, std::string> getCmdlineArgValue(const std::string &argKey) {
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bool isSuccess = false;
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std::string argValue;
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const auto cmdline = loadFileAsLine("/proc/cmdline");
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std::vector<std::string> cmdArgs;
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split(cmdline, cmdArgs, " ");
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std::find_if(
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std::cbegin(cmdArgs),
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std::cend(cmdArgs),
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[&isSuccess, &argValue, &argKey](const auto &arg) {
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bool result = false;
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std::vector<std::string> tokens;
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split(arg, tokens, "=");
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if (tokens.size() == 2 && tokens[0] == argKey) {
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result = true;
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isSuccess = result;
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argValue = tokens[1];
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}
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return result;
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}
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);
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return {isSuccess, argValue};
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}
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int displayCmdlineArg(const std::string &arg) {
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auto result = EXIT_FAILURE;
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const auto [isExist, value] = getCmdlineArgValue(arg);
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if (isExist) {
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result = EXIT_SUCCESS;
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std::cout << value << std::endl;
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} else {
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std::cerr << "Unable to find '" << arg << "=<value>' in kernel command line" << std::endl;
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}
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return result;
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}
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