Windows: skip permissions check on key

This code was attempting to check Linux file permissions
to determine if the key was accessible by other users, which
doesn't work, and therefore prevented users on Windows
to load keys.

Skipping this check on Windows (correspinding tests
were already skipped).

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 15d361fd77)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Upstream-commit: 6be8fce6f8
Component: cli

components/cli/cli/command/trust/key_load.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"runtime"
 
 	"github.com/docker/cli/cli"
 	"github.com/docker/cli/cli/command"
@@ -69,12 +70,14 @@ func loadPrivKey(streams command.Streams, keyPath string, options keyLoadOptions
 }
 
 func getPrivKeyBytesFromPath(keyPath string) ([]byte, error) {
-	fileInfo, err := os.Stat(keyPath)
-	if err != nil {
-		return nil, err
-	}
-	if fileInfo.Mode()&nonOwnerReadWriteMask != 0 {
-		return nil, fmt.Errorf("private key file %s must not be readable or writable by others", keyPath)
+	if runtime.GOOS != "windows" {
+		fileInfo, err := os.Stat(keyPath)
+		if err != nil {
+			return nil, err
+		}
+		if fileInfo.Mode()&nonOwnerReadWriteMask != 0 {
+			return nil, fmt.Errorf("private key file %s must not be readable or writable by others", keyPath)
+		}
 	}
 
 	from, err := os.OpenFile(keyPath, os.O_RDONLY, notary.PrivExecPerms)