feat: Add support for reading CPU (dev.cpu.*.temperature) and ACPI thermal zone (hw.acpi.thermal.tz*) temperature sensors on FreeBSD systems. (#2227)

Co-authored-by: roib <roib@elsec.us>

agent/sensors_freebsd_common.go

@@ -0,0 +1,81 @@
+//go:build freebsd || testing
+
+package agent
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/shirou/gopsutil/v4/sensors"
+)
+
+const (
+	freebsdZeroCelsiusDeciKelvin = 2731
+	freebsdAcpiThermalZoneCount  = 16
+)
+
+type freebsdSysctlUintReader func(name string) (uint32, error)
+
+func getFreeBSDSensorTemps(ctx context.Context, readSysctl freebsdSysctlUintReader) ([]sensors.TemperatureStat, error) {
+	cpuCount, err := readSysctl("hw.ncpu")
+	if err != nil {
+		return nil, err
+	}
+	temps := make([]sensors.TemperatureStat, 0, int(cpuCount)+freebsdAcpiThermalZoneCount)
+	for cpu := uint32(0); cpu < cpuCount; cpu++ {
+		select {
+		case <-ctx.Done():
+			return temps, ctx.Err()
+		default:
+		}
+
+		sensorName := fmt.Sprintf("dev.cpu.%d.temperature", cpu)
+		value, err := readSysctl(sensorName)
+		if err != nil {
+			continue
+		}
+		temp, ok := freebsdDeciKelvinToCelsius(value)
+		if !ok {
+			continue
+		}
+		temps = append(temps, sensors.TemperatureStat{
+			SensorKey:   sensorName,
+			Temperature: temp,
+		})
+	}
+
+	for zone := 0; zone < freebsdAcpiThermalZoneCount; zone++ {
+		select {
+		case <-ctx.Done():
+			return temps, ctx.Err()
+		default:
+		}
+
+		sensorName := fmt.Sprintf("hw.acpi.thermal.tz%d.temperature", zone)
+		value, err := readSysctl(sensorName)
+		if err != nil {
+			continue
+		}
+		temp, ok := freebsdDeciKelvinToCelsius(value)
+		if !ok {
+			continue
+		}
+		temps = append(temps, sensors.TemperatureStat{
+			SensorKey:   sensorName,
+			Temperature: temp,
+		})
+	}
+
+	return temps, nil
+}
+
+func freebsdDeciKelvinToCelsius(value uint32) (float64, bool) {
+	if value <= freebsdZeroCelsiusDeciKelvin {
+		return 0, false
+	}
+	temp := float64(int64(value)-freebsdZeroCelsiusDeciKelvin) / 10
+	if temp <= 0 || temp >= 200 {
+		return 0, false
+	}
+	return temp, true
+}