src: add preset for select wsl version on install

src/install/install.go

@@ -4,8 +4,11 @@ import (
 	"bufio"
 	"fmt"
 	"os"
+	"os/exec"
 	"path/filepath"
+	"strconv"
 
+	"github.com/yuk7/wsldl/lib/preset"
 	"github.com/yuk7/wsldl/lib/utils"
 	"github.com/yuk7/wsldl/lib/wslapi"
 )
@@ -37,6 +40,18 @@ func Execute(name string, args []string) {
 		}
 
 		err := Install(name, rootPath, showProgress)
+		if err != nil {
+			utils.ErrorExit(err, showProgress, true, args == nil)
+		}
+
+		json, err2 := preset.ReadParsePreset()
+		if err2 == nil {
+			if json.WslVersion == 1 || json.WslVersion == 2 {
+				wslexe := os.Getenv("SystemRoot") + "\\System32\\wsl.exe"
+				_, err = exec.Command(wslexe, "--set-version", name, strconv.Itoa(json.WslVersion)).Output()
+			}
+		}
+
 		if err == nil {
 			if showProgress {
 				utils.StdoutGreenPrintln("Installation complete")

src/lib/preset/model_preset.go

@@ -0,0 +1,5 @@
+package preset
+
+type Preset struct {
+	WslVersion int `json:"wslversion,omitempty"`
+}

src/lib/preset/preset.go

@@ -0,0 +1,43 @@
+package preset
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"muzzammil.xyz/jsonc"
+)
+
+// ReadPresetJSON reads preset.json configuration json file
+func ReadPresetJSON() (res string, err error) {
+	efPath, _ := os.Executable()
+	dir := filepath.Dir(efPath)
+	json := filepath.Join(dir, "preset.json")
+	b, err := ioutil.ReadFile(json)
+	if err != nil {
+		return
+	}
+	res = string(b)
+	return
+}
+
+// ParsePresetJSON parses preset.json configuration json string
+func ParsePresetJSON(str string) (res Preset, err error) {
+	var c Preset
+	err = jsonc.Unmarshal([]byte(str), &c)
+	if err != nil {
+		return
+	}
+	res = c
+	return
+}
+
+// ReadParsePreset reads and parses preset.json configuration file
+func ReadParsePreset() (conf Preset, err error) {
+	json, err := ReadPresetJSON()
+	if err != nil {
+		return
+	}
+	conf, err = ParsePresetJSON(json)
+	return
+}