Use apm(8) on OpenBSD for charger and battery status

battery_bsd.go

@@ -1,5 +1,5 @@
-//go:build openbsd || freebsd || netbsd
-// +build openbsd freebsd netbsd
+//go:build freebsd || netbsd
+// +build freebsd netbsd
 
 package dryvers
 

battery_openbsd.go

@@ -0,0 +1,48 @@
+//go:build openbsd
+// +build openbsd
+
+package dryvers
+
+import (
+	"errors"
+	"os/exec"
+)
+
+var errNoApmOutput = errors.New("failed to find apm output")
+
+const apmBin = "/usr/sbin/apm"
+
+func (b *Battery) PluggedIn() (bool, error) {
+	cmd := exec.Command(apmBin, "-a")
+	val, err := cmd.CombinedOutput()
+	if err != nil {
+		return false, err
+	}
+
+	if len(val) == 0 {
+		return false, errNoApmOutput
+	}
+
+	return val[0] == 1, nil
+}
+
+// Get returns the current battery level (between 0 and 1) or
+// an error if there was a problem.
+func (b *Battery) Get() (float64, error) {
+	cmd := exec.Command(apmBin, "-l")
+	val, err := cmd.CombinedOutput()
+	if err != nil {
+		return 0, err
+	}
+
+	if len(val) == 0 {
+		return 0, errNoApmOutput
+	}
+
+	percent := int(val[0])
+	if percent == 0 { // avoid 0/100 below
+		return 0, nil
+	}
+
+	return float64(percent) / 100, nil
+}