void SysInfo::init_sys_info()

in src/sys_info.cc [99:198]

• 66 lines of code
• 12 McCabe index (conditional complexity)

	void SysInfo::init_sys_info(const char * affinity_set) {

		// Prevent the (perceived) cpu topology from being changed at runtime
		static bool called = false;
		if (called) {
			return;
		}
		called = true;

		std::string line;
		std::ifstream onlinefile("/sys/devices/system/cpu/online");

		if (!onlinefile.is_open()) {
			fprintf(stderr, "Error opening /sys/devices/system/cpu/online\n");
			exit(1);
		}

		std::getline(onlinefile,line);

		onlinefile.close();

		online_cpus = str_to_cpu_set(line.c_str());

		// Get lowest and highest cpu numbers
		cpulo = *online_cpus.begin();
		cpuhi = *online_cpus.rbegin();

		if (affinity_set) {
			affinity_cpus = str_to_cpu_set(affinity_set);
		} else {
			affinity_cpus = online_cpus;
		}
		
		// ************* block device stuff ****************

		// all block devices are listed here, including partitions
		DIR * c_b_dir = opendir("/sys/class/block");
		if (c_b_dir == nullptr) {
			fprintf(stderr, "Failed to get list of block devices from /sys/class/block");
			perror("opendir");
			exit(1);
		}

		struct dirent *c_b_dirent;
		int err;
		std::string temp;
		std::set<std::string> block_devices;

		// loop through the directory stream until we reach the end
		while (1) {
			// In modern implementations (including the glibc implementation),
			// concurrent calls to readdir() that specify different directory
			// streams are thread-safe. See "man readdir".
			errno = 0;
			c_b_dirent = readdir(c_b_dir);

			if (errno) { // only error is EBADF for c_b_dir, realllly unlikely
				fprintf(stderr, "Error in device info initialization\n");
				perror("readdir");
				exit(1);
			}

			if (!c_b_dirent)
				break;

			temp = std::string(c_b_dirent->d_name);
			// ignore hidden files
			if (temp[0] == '.') continue;
			block_devices.insert(temp);
		}
		closedir(c_b_dir);

		std::string dev_path;
		struct stat dev_stat = {0};

		// look each partition up in /dev, compare device_id until we find it
		for (auto& str : block_devices) {
			dev_path = "/dev/" + str;
			int err = stat(dev_path.c_str(), &dev_stat);
			if (err) {
				fprintf(stderr, "Unexpected error '%d: %s' when statting %s!\n", errno, strerror(errno), dev_path.c_str());
				perror("stat");
				exit(1);
			}
			//printf("mapping %u,%u to %s\n", major(dev_stat.st_rdev), minor(dev_stat.st_rdev), str.c_str());
			// map it for later!
			id_to_device[dev_stat.st_rdev] = str;
		}

		// ************* fua caching ****************

		std::ifstream fuafile("/sys/module/libata/parameters/fua");

		// if we can't open it, the kernel probably doesn't know the state of fua, so ignore
		if (fuafile.is_open()) {
			std::getline(fuafile,line);
			fuafile.close();
			caching_options = "fua="+line;
		}
	}