Preface:
I am not a good developer and am just getting started, the code below is part of a larger program I am building and has only been temporarily placed in the main cpp file. I am aware that the structure still needs improvement only I want to get it running first.
Problem:
I have the last days desperately trying to find documentation, but since I could find nothing but this [https://www.freedesktop.org/software/systemd/man/sd-device.html] and I have tried to work through the source code on github.
I had previously used the libudev library to read BLOCK devices and get values from them which worked, however after further exposure to this topic I read that it is no longer recommended to use libudev and switch to systemd/sd-device.
The code below doesn't output an error but it also doesn't run through the loop because "sd_device_enumerator_get_device_next(enumerator)" always returns a NULL pointer. Even after a very long search I can't find any documentation for systemd/sd-device and even reading through the src data I can't figure it out.
This is my attempt, this should basically run through all BLOCK devices and read out certain values, for testing I have entered "ID_PART_TABLE_TYPE".
main.h
#ifndef main_h
#define main_h
#include <string>
#include <bitset>
#include <iostream>
#include <fstream>
#include <sstream>
#include <regex>
#include <vector>
#include <cstring>
#include <stdio.h>
#include <dirent.h>
#include <systemd/sd-device.h>
using std::cout;
using std::endl;
using std::string;
using std::to_string;
using std::cin;
using std::fstream;
using std::ifstream;
using std::ofstream;
using std::vector;
// File: classes/drives-info.cpp
/*
class drivesInfo{
public:
vector<string> blockDevs;
vector< vector<string> > blockDevsParts;
int get_blockDevs();
};
*/
#endif
main.cpp
#include "main.h"
int test0() {
int r;
sd_device_enumerator *enumerator = NULL;
sd_device *dev = NULL;
// Initialize the Device-Enumerator
r = sd_device_enumerator_new(&enumerator);
if (r < 0) {
printf("Error | Initialize the Device-Enumerator: %s\n", strerror(-r));
}
// Set Filter to BLOCK
r = sd_device_enumerator_add_match_subsystem(enumerator, "block", 0);
if (r < 0) {
printf("Error | Set Filter to BLOCK: %s\n", strerror(-r));
}
// Loop to run through all BLOCK devices
if (r >= 0) {
while ((dev = sd_device_enumerator_get_device_next(enumerator)) != NULL) {
const char *pt_type = NULL;
r = sd_device_get_property_value(dev, "ID_PART_TABLE_TYPE", &pt_type);
if (r >= 0) {
printf("Device: %s\n");
printf("ID_PART_TABLE_TYPE: %s\n", pt_type);
}
sd_device_unref(dev);
dev = NULL;
cout << "loop" << endl;
}
}
if (r < 0) {
printf("Error | at Loop to run through all BLOCK devices: %s\n", strerror(-r));
}
if (enumerator) {
sd_device_enumerator_unref(enumerator);
}
if (dev) {
sd_device_unref(dev);
}
return r < 0 ? 1 : 0;
}
int main() {
// drivesInfo drives;
//
// drives.get_blockDevs();
//
// for (const string &entry : drives.blockDevs){
// cout << entry << endl;
// }
test0();
return 0;
}
