Replace deprecated os.Is{Not,}Exist calls

This commit replaces deprecated calls to `os.Is{Not,}Exist` with the
newer `errors.Is(err, fs.Err{Not,}Exist)`.

internal/dis/component/exporter/exporter.go

@@ -2,8 +2,9 @@ package exporter
 
 import (
 	"crypto/rand"
+	"errors"
 	"fmt"
-	"os"
+	"io/fs"
 	"path/filepath"
 	"time"
 
@@ -72,7 +73,7 @@ func (*Exporter) newSnapshotName(prefix string) string {
 // NewStagingDir returns the path to a new snapshot directory.
 // The directory is guaranteed to have been freshly created.
 func (dis *Exporter) NewStagingDir(prefix string) (path string, err error) {
-	for path == "" || os.IsExist(err) {
+	for path == "" || errors.Is(err, fs.ErrExist) {
 		path = filepath.Join(dis.StagingPath(), dis.newSnapshotName(prefix))
 		err = fsx.Mkdir(path, fsx.DefaultFilePerm)
 	}

internal/dis/component/exporter/iface.go

@@ -2,7 +2,9 @@ package exporter
 
 import (
 	"context"
+	"errors"
 	"io"
+	"io/fs"
 	"os"
 	"path/filepath"
 
@@ -75,7 +77,7 @@ func (exporter *Exporter) MakeExport(ctx context.Context, progress io.Writer, ta
 	// create the staging directory
 	logging.LogMessage(progress, ctx, "Creating staging directory")
 	err = fsx.Mkdir(stagingDir, fsx.DefaultDirPerm)
-	if !os.IsExist(err) && err != nil {
+	if !errors.Is(err, fs.ErrExist) && err != nil {
 		return err
 	}
 

internal/dis/component/exporter/logger/logger.go

@@ -2,6 +2,8 @@ package logger
 
 import (
 	"context"
+	"errors"
+	"io/fs"
 	"os"
 
 	"github.com/FAU-CDI/wisski-distillery/internal/dis/component"
@@ -63,7 +65,7 @@ func (log *Logger) Log(ctx context.Context) ([]models.Export, error) {
 	// partition out the exports that have been deleted!
 	parts := collection.Partition(exports, func(s models.Export) bool {
 		_, err := os.Stat(s.Path)
-		return !os.IsNotExist(err)
+		return !errors.Is(err, fs.ErrNotExist)
 	})
 
 	// go and delete them!

internal/dis/component/ssh2/server_hostkeys.go

@@ -8,6 +8,7 @@ import (
 	"crypto/x509"
 	"encoding/pem"
 	"io"
+	"io/fs"
 	"os"
 
 	"github.com/FAU-CDI/wisski-distillery/pkg/fsx"
@@ -65,7 +66,7 @@ func (ssh2 *SSH2) UseOrMakeHostKey(progress io.Writer, ctx context.Context, serv
 func (ssh2 *SSH2) ReadOrMakeHostKey(progress io.Writer, ctx context.Context, privateKeyPath string, algorithm HostKeyAlgorithm) (key gossh.Signer, err error) {
 	hostKey := NewHostKey(algorithm)
 
-	if _, e := os.Lstat(privateKeyPath); os.IsNotExist(e) { // path doesn't exist => generate a new key there!
+	if _, e := os.Lstat(privateKeyPath); errors.Is(e, fs.ErrNotExist) { // path doesn't exist => generate a new key there!
 		err = ssh2.makeHostKey(progress, ctx, hostKey, privateKeyPath)
 		if err != nil {
 			err = errors.Wrap(err, "Unable to generate new host key")