refactor to reduce duplicated error parsing

Signed-off-by: Peter Hunt <pehunt@redhat.com>

libpod/define/exec_codes.go

@@ -1,5 +1,9 @@
 package define
 
+import (
+	"github.com/pkg/errors"
+)
+
 const (
 	// ExecErrorCodeGeneric is the default error code to return from an exec session if libpod failed
 	// prior to calling the runtime
@@ -11,3 +15,16 @@ const (
 	// ExecErrorCodeNotFound is the error code to return when a command cannot be found
 	ExecErrorCodeNotFound = 127
 )
+
+// TranslateExecErrorToExitCode takes an error and checks whether it
+// has a predefined exit code associated. If so, it returns that, otherwise it returns
+// the exit code originally stated in libpod.Exec()
+func TranslateExecErrorToExitCode(originalEC int, err error) int {
+	if errors.Cause(err) == ErrOCIRuntimePermissionDenied {
+		return ExecErrorCodeCannotInvoke
+	}
+	if errors.Cause(err) == ErrOCIRuntimeNotFound {
+		return ExecErrorCodeNotFound
+	}
+	return originalEC
+}

pkg/adapter/containers.go

@@ -1001,13 +1001,7 @@ func (r *LocalRuntime) ExecContainer(ctx context.Context, cli *cliconfig.ExecVal
 	streams.AttachError = true
 
 	ec, err = ExecAttachCtr(ctx, ctr.Container, cli.Tty, cli.Privileged, envs, cmd, cli.User, cli.Workdir, streams, cli.PreserveFDs, cli.DetachKeys)
-	if errors.Cause(err) == define.ErrOCIRuntimePermissionDenied {
-		ec = 126
-	}
-	if errors.Cause(err) == define.ErrOCIRuntimeNotFound {
-		ec = 127
-	}
-	return ec, err
+	return define.TranslateExecErrorToExitCode(ec, err), err
 }
 
 // Prune removes stopped containers

pkg/varlinkapi/containers.go

@@ -837,15 +837,9 @@ func (i *LibpodAPI) ExecContainer(call iopodman.VarlinkCall, opts iopodman.ExecO
 
 	ecErr := <-ecErrChan
 
-	exitCode := ecErr.ExitCode
-	if errors.Cause(ecErr.Error) == define.ErrOCIRuntimePermissionDenied {
-		exitCode = define.ExecErrorCodeCannotInvoke
-	}
-	if errors.Cause(ecErr.Error) == define.ErrOCIRuntimeNotFound {
-		exitCode = define.ExecErrorCodeNotFound
-	}
+	exitCode := define.TranslateExecErrorToExitCode(int(ecErr.ExitCode), ecErr.Error)
 
-	if err = virtwriter.HangUp(writer, exitCode); err != nil {
+	if err = virtwriter.HangUp(writer, uint32(exitCode)); err != nil {
 		logrus.Errorf("ExecContainer failed to HANG-UP on %s: %s", ctr.ID(), err.Error())
 	}