refactor: move from io/ioutil to io and os packages

The io/ioutil package has been deprecated as of Go 1.16, see
https://golang.org/doc/go1.16#ioutil. This commit replaces the existing
io/ioutil functions with their new definitions in io and os packages.

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

cmd/fs.go

@@ -6,7 +6,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"path"
@@ -50,7 +49,7 @@ func (fs *FSHelper) FileExists(path string) bool {
 
 // FindFile returns the first occurrence of match inside path.
 func (fs *FSHelper) FindFile(path, match string) (string, error) {
-	files, err := ioutil.ReadDir(path)
+	files, err := os.ReadDir(path)
 	if err != nil {
 		return "", err
 	}
@@ -69,7 +68,7 @@ func (fs *FSHelper) FindFile(path, match string) (string, error) {
 func (fs *FSHelper) CreateFile(filename string, data []byte) error {
 	// Ensure directory exists
 	fs.MkDirs(filepath.Dir(filename))
-	return ioutil.WriteFile(filename, data, 0644)
+	return os.WriteFile(filename, data, 0644)
 }
 
 // MkDirs creates the given nested directories.
@@ -156,14 +155,14 @@ func (fs *FSHelper) LoadRelativeFile(relativePath string) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	return ioutil.ReadFile(fullPath)
+	return os.ReadFile(fullPath)
 }
 
 // GetSubdirs will return a list of FQPs to subdirectories in the given directory
 func (d *Dir) GetSubdirs() (map[string]string, error) {
 
 	// Read in the directory information
-	fileInfo, err := ioutil.ReadDir(d.fullPath)
+	fileInfo, err := os.ReadDir(d.fullPath)
 	if err != nil {
 		return nil, err
 	}
@@ -215,7 +214,7 @@ func (fs *FSHelper) SaveAsJSON(data interface{}, filename string) error {
 	e.SetIndent("", "  ")
 	e.Encode(data)
 
-	err := ioutil.WriteFile(filename, buf.Bytes(), 0755)
+	err := os.WriteFile(filename, buf.Bytes(), 0755)
 	if err != nil {
 		return err
 	}
@@ -231,7 +230,7 @@ func (fs *FSHelper) LoadAsString(filename string) (string, error) {
 
 // LoadAsBytes returns the contents of the file as a byte slice
 func (fs *FSHelper) LoadAsBytes(filename string) ([]byte, error) {
-	return ioutil.ReadFile(filename)
+	return os.ReadFile(filename)
 }
 
 // FileMD5 returns the md5sum of the given file

cmd/github.go

@@ -3,7 +3,7 @@ package cmd
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"sort"
 )
@@ -28,7 +28,7 @@ func (g *GitHubHelper) GetVersionTags() ([]*SemanticVersion, error) {
 	if err != nil {
 		return result, err
 	}
-	body, err := ioutil.ReadAll(resp.Body)
+	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return result, err
 	}

cmd/linux.go

@@ -2,7 +2,6 @@ package cmd
 
 import (
 	"fmt"
-	"io/ioutil"
 	"net/url"
 	"os"
 	"runtime"
@@ -95,7 +94,7 @@ func GetLinuxDistroInfo() *DistroInfo {
 	}
 	_, err := os.Stat("/etc/os-release")
 	if !os.IsNotExist(err) {
-		osRelease, _ := ioutil.ReadFile("/etc/os-release")
+		osRelease, _ := os.ReadFile("/etc/os-release")
 		result = parseOsRelease(string(osRelease))
 	}
 	return result

cmd/package.go

@@ -7,7 +7,6 @@ import (
 	"fmt"
 	"image"
 	"image/png"
-	"io/ioutil"
 	"os"
 	"path"
 	"path/filepath"
@@ -244,7 +243,7 @@ func (b *PackageHelper) packageOSX(po *ProjectOptions) error {
 		// No - create a new plist from our defaults
 		tmpl := template.New("infoPlist")
 		plistFile := filepath.Join(b.getPackageFileBaseDir(), "info.plist")
-		infoPlist, err := ioutil.ReadFile(plistFile)
+		infoPlist, err := os.ReadFile(plistFile)
 		if err != nil {
 			return err
 		}
@@ -258,13 +257,13 @@ func (b *PackageHelper) packageOSX(po *ProjectOptions) error {
 		}
 
 		// Save to the package
-		err = ioutil.WriteFile(plistFilename, tpl.Bytes(), 0644)
+		err = os.WriteFile(plistFilename, tpl.Bytes(), 0644)
 		if err != nil {
 			return err
 		}
 
 		// Also write to project directory for customisation
-		err = ioutil.WriteFile(customPlist, tpl.Bytes(), 0644)
+		err = os.WriteFile(customPlist, tpl.Bytes(), 0644)
 		if err != nil {
 			return err
 		}
@@ -334,12 +333,12 @@ func (b *PackageHelper) PackageWindows(po *ProjectOptions, cleanUp bool) error {
 	tgtRCFile := filepath.Join(outputDir, basename+".rc")
 	if !b.fs.FileExists(tgtRCFile) {
 		srcRCfile := filepath.Join(b.getPackageFileBaseDir(), "wails.rc")
-		rcfilebytes, err := ioutil.ReadFile(srcRCfile)
+		rcfilebytes, err := os.ReadFile(srcRCfile)
 		if err != nil {
 			return err
 		}
 		rcfiledata := strings.Replace(string(rcfilebytes), "$NAME$", basename, -1)
-		err = ioutil.WriteFile(tgtRCFile, []byte(rcfiledata), 0755)
+		err = os.WriteFile(tgtRCFile, []byte(rcfiledata), 0755)
 		if err != nil {
 			return err
 		}
@@ -387,11 +386,11 @@ func (b *PackageHelper) copyIcon() (string, error) {
 
 		// Install default icon
 		iconfile := filepath.Join(b.getPackageFileBaseDir(), "icon.png")
-		iconData, err := ioutil.ReadFile(iconfile)
+		iconData, err := os.ReadFile(iconfile)
 		if err != nil {
 			return "", err
 		}
-		err = ioutil.WriteFile(srcIcon, iconData, 0644)
+		err = os.WriteFile(srcIcon, iconData, 0644)
 		if err != nil {
 			return "", err
 		}

cmd/project.go

@@ -3,7 +3,6 @@ package cmd
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -310,14 +309,14 @@ func (po *ProjectOptions) WriteProjectConfig() error {
 		return err
 	}
 
-	return ioutil.WriteFile(targetFile, filedata, 0600)
+	return os.WriteFile(targetFile, filedata, 0600)
 }
 
 // LoadConfig loads the project configuration file from the
 // given directory
 func (po *ProjectOptions) LoadConfig(projectDir string) error {
 	targetFile := filepath.Join(projectDir, "project.json")
-	rawBytes, err := ioutil.ReadFile(targetFile)
+	rawBytes, err := os.ReadFile(targetFile)
 	if err != nil {
 		return err
 	}

cmd/system.go

@@ -3,7 +3,6 @@ package cmd
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
@@ -124,7 +123,7 @@ func (s *SystemHelper) setup() error {
 	if err != nil {
 		return err
 	}
-	err = ioutil.WriteFile(s.wailsSystemConfig, configData, 0755)
+	err = os.WriteFile(s.wailsSystemConfig, configData, 0755)
 	if err != nil {
 		return err
 	}
@@ -207,11 +206,11 @@ func (sc *SystemConfig) Save(filename string) error {
 	}
 
 	// Write it out to the config file
-	return ioutil.WriteFile(filename, theJSON, 0644)
+	return os.WriteFile(filename, theJSON, 0644)
 }
 
 func (sc *SystemConfig) load(filename string) error {
-	configData, err := ioutil.ReadFile(filename)
+	configData, err := os.ReadFile(filename)
 	if err != nil {
 		return err
 	}

cmd/templates.go

@@ -4,8 +4,8 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"log"
+	"os"
 	"path/filepath"
 	"runtime"
 	"strings"
@@ -125,7 +125,7 @@ func (t *TemplateHelper) LoadMetadata(dir string) (*TemplateMetadata, error) {
 	if !t.fs.FileExists(templateFile) {
 		return nil, nil
 	}
-	rawJSON, err := ioutil.ReadFile(templateFile)
+	rawJSON, err := os.ReadFile(templateFile)
 	if err != nil {
 		return nil, err
 	}

cmd/wails/15_migrate.go

@@ -3,7 +3,6 @@ package main
 import (
 	"bufio"
 	"fmt"
-	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
@@ -305,7 +304,7 @@ func updateWailsVersion(currentVersion, latestVersion *semver.Version) error {
 	new := fmt.Sprintf("%s v%s", wailsModule, latestVersion)
 
 	goMod = strings.Replace(goMod, old, new, -1)
-	err := ioutil.WriteFile(goModFile, []byte(goMod), 0600)
+	err := os.WriteFile(goModFile, []byte(goMod), 0600)
 	if err != nil {
 		checkSpinner.Error()
 		return err
@@ -343,7 +342,7 @@ func patchMainJS() error {
 	newStartLine := `Wails.Init`
 	mainJSContents = strings.Replace(mainJSContents, oldStartLine, newStartLine, -1)
 
-	err := ioutil.WriteFile(mainJSFile, []byte(mainJSContents), 0600)
+	err := os.WriteFile(mainJSFile, []byte(mainJSContents), 0600)
 	if err != nil {
 		checkSpinner.Error()
 		return err

cmd/wails/9_issue.go

@@ -2,7 +2,7 @@ package main
 
 import (
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"net/url"
 	"os"
@@ -112,7 +112,7 @@ To help you in this process, we will ask for some information, add Go/Wails deta
 			os.Exit(1)
 		}
 		defer resp.Body.Close()
-		template, _ := ioutil.ReadAll(resp.Body)
+		template, _ := io.ReadAll(resp.Body)
 		body := string(template)
 		body = "**Description**\n" + (strings.Split(body, "**Description**")[1])
 		fullURL := "https://github.com/wailsapp/wails/issues/new?"