libsensors-c++

The lm-sensors package allows linux users to interact with the hardware monitoring chip(s) in their systems and includes libsensors, a C API to these chips. The aim of libsensors-c++ is to provide an easy to use, class-based C++ interface to libsensors.

Installation

A C++17-conforming compiler, libsensors and its development headers are required.

$ git clone [email protected]:sfranzen/libsensors-cpp
$ cd libsensors-cpp
$ cmake -Bbuild
$ cmake --build build
$ sudo cmake --install build

Installation includes a CMake configuration file that allows your own CMake project to import this library using find_package(sensors-c++).

Example

#include <sensors-c++/sensors.h>
#include <iostream>
//...
sensors::subfeature temp {"/sys/class/hwmon/hwmon0/temp1_input"};
std::cout << temp.read() << '\n';

Usage

The library provides two public headers, similar to libsensors: <sensors-c++/sensors.h> and <sensors-c++/error.h>. Neither includes any libsensors headers and it is not necessary to initialise or interact with libsensors directly yourself. All classes and functions are defined in the namespace sensors and named like their counterparts in libsensors.

Classes

The following classes are provided in the <sensors-c++/sensors.h> header:

• class bus_id represents the bus a chip_name was found on;
• class chip_name represents a sensor chip hosting one or more features;
• class feature represents a sensor feature hosting one or more subfeatures, e.g. fan1, temp2;
• class subfeature represents a particular input/output on a feature, e.g. fan1_input, temp2_alarm.

None of these classes have a default constructor, but all support copy and move semantics. There are two ways of constructing objects:

• The function std::vector<chip_name> sensors::get_detected_chips() returns a list of all chips found on your system. New instances can be copy/move-constructed from these, and chip_name and feature objects can be queried for their child features and subfeatures, respectively;
• The chip_name, feature and subfeature classes have constructors that accept std::string arguments. These can be used to instantiate a component based on its path in the /sys/class/hwmon device directory, such as /sys/class/hwmon/hwmon0/temp1_input.

All of libsensors' enumerations and macro constants are mapped onto similar, scoped C++ enums:

• enum class bus_type;
• enum class feature_type;
• enum class subfeature_type;

Configuration files

This library automatically calls sensors_init(FILE*) to allocate the resources for libsensors. You can optionally specify a configuration file to be used in this call using sensors::load_config(std::string const& path). Note that this requires calling sensors_cleanup(); referencing any previously constructed sensor objects is undefined behaviour. Not calling this function or specifying an empty string will cause a nullptr to be passed instead and the default configuration to be used.

Exceptions

Error conditions, including those in libsensors library calls, are reported as exceptions. All exceptions thrown by sensors-c++ are defined in <sensors-c++/error.h> and derived from sensors::error, which is itself a std::runtime_error.

Thread safety

No explicit measures have been taken and sensors::load_config() in particular is not thread safe. Creating sensor objects and reading their values should be safe, although this has not been rigorously tested.