Add sysfs method to get battery charge for linux

cmd/i3status-go/default-config.json

@@ -518,6 +518,15 @@
 "battery": {
 	"enabled": false,
 
+	// Valid only on linux, where we have mounted sysfs and /sys/class/power_supply/BAT0/capacity available
+	"use_sysfs": false,
+
+	// it is possible to set files here, if none set, /sys/class/power_supply/BAT0/capacity will be taken.
+	"sysfs_files": [
+		"/sys/class/power_supply/BAT0/capacity",
+		"/sys/class/power_supply/HIDP0/capacity"
+	],
+
 	// If omitted set to default color defined up here.
 	"color": "#3e78fd",
 

internal/lib/batteries.go

@@ -2,7 +2,12 @@ package lib
 
 import (
 	"fmt"
+	"log"
 	"math"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
 	"time"
 
 	"github.com/distatus/battery"
@@ -11,9 +16,6 @@ import (
 // UpdateBatteryInfo updates info about battery charge.
 func (c *MyConfig) UpdateBatteryInfo() {
 	var (
-		ch                 int
-		status             string
-		Batts              string
 		InitialDelay       = 100 * time.Millisecond
 		LoopIterationDelay = 5 * time.Second
 		Delay              = InitialDelay
@@ -26,9 +28,82 @@ func (c *MyConfig) UpdateBatteryInfo() {
 			ticker.Reset(Delay)
 		}
 
-		batteries, _ := battery.GetAll()
+		var (
+			batteries []*battery.Battery = []*battery.Battery{}
+			Batts     string
+			ch        int
+			status    string
+		)
+
+		if c.Battery.UseSysfs {
+			for _, file := range c.Battery.SysfsFiles {
+				var batt battery.Battery
+
+				_, err := os.Stat(file)
+
+				// If file exists.
+				if !os.IsNotExist(err) {
+					var (
+						myCharge string
+						myStatus string
+					)
+
+					b, err := os.ReadFile(file)
+
+					if err != nil {
+						log.Printf("Unable to read file %s: %s", file, err)
+						continue
+					}
+
+					myCharge = strings.Trim(string(b), "\n")
+
+					statusFile := filepath.Dir(file) + "/status"
+
+					// If file exists.
+					if !os.IsNotExist(err) {
+						b, err := os.ReadFile(statusFile)
+
+						if err != nil {
+							log.Printf("Unable to read file %s: %s", statusFile, err)
+							continue
+						}
+
+						myStatus = strings.Trim(string(b), "\n")
+					} else {
+						continue
+					}
+
+					// Make stub battery class :) .
+					switch myStatus {
+					case "Charging":
+						batt.State.Raw = battery.Charging
+					case "Discharging":
+						batt.State.Raw = battery.Discharging
+					case "Empty":
+						batt.State.Raw = battery.Empty
+					case "Full":
+						batt.State.Raw = battery.Full
+					default:
+						batt.State.Raw = battery.Unknown
+					}
+
+					ch, err := strconv.Atoi(myCharge)
+
+					if err != nil {
+						log.Printf("Unable to convert string from file %s to integer", file)
+						continue
+					}
+
+					batt.Current = float64(ch)
+
+					batteries = append(batteries, &batt)
+				}
+			}
+		} else {
+			batteries, _ = battery.GetAll()
 			// In theory, this module should give for each entry its separate err, but in practice it gives
 			// one single err for all entries, so we cannot detemine whist exatly entry errored.
+		}
 
 		var (
 			battsInfo string
@@ -49,7 +124,11 @@ func (c *MyConfig) UpdateBatteryInfo() {
 
 			// N.B. there can be case when battery is overcharged and shows >100%. It also can indicate that
 			//      calibration data is out of date and battery should be re-calibrated.
+			if c.Battery.UseSysfs {
+				ch = int(b.Current)
+			} else {
 				ch = int(math.Round((b.Full - (b.Full - b.Current)) * (100 / b.Full)))
+			}
 
 			switch {
 			case ch <= 500 && ch >= 84:

internal/lib/config.go

@@ -135,6 +135,8 @@ type MyConfig struct {
 
 	Battery struct {
 		Enabled        bool     `json:"enabled,omitempty"`
+		UseSysfs       bool     `json:"use_sysfs,omitempty"`
+		SysfsFiles     []string `json:"sysfs_files,omitempty"`
 		Color          string   `json:"color,omitempty"`
 		Background     string   `json:"background,omitempty"`
 		Font           string   `json:"font,omitempty"`
@@ -778,6 +780,15 @@ func ReadConf(defaultConfig []byte) (*MyConfig, error) {
 	}
 
 	// sampleConfig.Battery.Enabled will be false if not set in config
+	// sampleConfig.Battery.UseSysfs will be false if not set in config
+
+	if len(sampleConfig.Battery.SysfsFiles) == 0 {
+		sampleConfig.Battery.SysfsFiles = append(
+			sampleConfig.Battery.SysfsFiles,
+			"/sys/class/power_supply/BAT0/capacity",
+		)
+	}
+
 	if sampleConfig.Battery.Color == "" {
 		sampleConfig.Battery.Color = sampleConfig.Color
 	}

internal/lib/spawn.go

@@ -11,6 +11,7 @@ import (
 // Spawner forks and execs given program, and also detaches form its control tty.
 func (c *MyConfig) Spawner() {
 	for prg := range c.Channels.RunChan {
+		<-time.After(25 * time.Millisecond)
 		devnullR, _ := os.Open(os.DevNull)
 		devnullW, _ := os.OpenFile(os.DevNull, os.O_WRONLY|os.O_APPEND, 0644)