module-transaction: Add support for setting/getting module data

Module data is data associated with a module handle that is available
for the whole module loading time so it can be used also during
different operations.

We use cgo handles to preserve the life of the go objects so any value
can be associated with a pam transaction.

module-transaction_test.go

@@ -8,6 +8,13 @@ import (
 	"testing"
 )
 
+func ensureNoError(t *testing.T, err error) {
+	t.Helper()
+	if err != nil {
+		t.Fatalf("unexpected error %v", err)
+	}
+}
+
 func Test_NewNullModuleTransaction(t *testing.T) {
 	t.Parallel()
 	mt := moduleTransaction{}
@@ -68,6 +75,24 @@ func Test_NewNullModuleTransaction(t *testing.T) {
 				return mt.GetUser("prompt")
 			},
 		},
+		"GetData": {
+			testFunc: func(t *testing.T) (any, error) {
+				t.Helper()
+				return mt.GetData("some-data")
+			},
+		},
+		"SetData": {
+			testFunc: func(t *testing.T) (any, error) {
+				t.Helper()
+				return nil, mt.SetData("foo", []interface{}{})
+			},
+		},
+		"SetData-nil": {
+			testFunc: func(t *testing.T) (any, error) {
+				t.Helper()
+				return nil, mt.SetData("foo", nil)
+			},
+		},
 	}
 
 	for name, tc := range tests {
@@ -313,6 +338,63 @@ func Test_MockModuleTransaction(t *testing.T) {
 				return mt.getUserImpl(mock, "who are you?")
 			},
 		},
+		"GetData-not-available": {
+			expectedError: ErrNoModuleData,
+			mockExpectations: mockModuleTransactionExpectations{
+				DataKey: "not-available-data"},
+			expectedValue: nil,
+			testFunc: func(mock *mockModuleTransaction) (any, error) {
+				return mt.getDataImpl(mock, "not-available-data")
+			},
+		},
+		"GetData-not-available-other-failure": {
+			expectedError: ErrBuf,
+			mockExpectations: mockModuleTransactionExpectations{
+				DataKey: "not-available-data"},
+			mockRetData:   mockModuleTransactionReturnedData{Status: ErrBuf},
+			expectedValue: nil,
+			testFunc: func(mock *mockModuleTransaction) (any, error) {
+				return mt.getDataImpl(mock, "not-available-data")
+			},
+		},
+		"SetData-empty-nil": {
+			expectedError: ErrNoModuleData,
+			expectedValue: nil,
+			testFunc: func(mock *mockModuleTransaction) (any, error) {
+				ensureNoError(mock.T, mt.setDataImpl(mock, "", nil))
+				return mt.getDataImpl(mock, "")
+			},
+		},
+		"SetData-empty-to-value": {
+			expectedValue: []string{"hello", "world"},
+			testFunc: func(mock *mockModuleTransaction) (any, error) {
+				ensureNoError(mock.T, mt.setDataImpl(mock, "",
+					[]string{"hello", "world"}))
+				return mt.getDataImpl(mock, "")
+			},
+		},
+		"SetData-to-value": {
+			expectedValue: []interface{}{"a string", true, 0.55, errors.New("oh no")},
+			mockExpectations: mockModuleTransactionExpectations{
+				DataKey: "some-data"},
+			testFunc: func(mock *mockModuleTransaction) (any, error) {
+				ensureNoError(mock.T, mt.setDataImpl(mock, "some-data",
+					[]interface{}{"a string", true, 0.55, errors.New("oh no")}))
+				return mt.getDataImpl(mock, "some-data")
+			},
+		},
+		"SetData-to-value-replacing": {
+			expectedValue: "just a value",
+			mockExpectations: mockModuleTransactionExpectations{
+				DataKey: "replaced-data"},
+			testFunc: func(mock *mockModuleTransaction) (any, error) {
+				ensureNoError(mock.T, mt.setDataImpl(mock, "replaced-data",
+					[]interface{}{"a string", true, 0.55, errors.New("oh no")}))
+				ensureNoError(mock.T, mt.setDataImpl(mock, "replaced-data",
+					"just a value"))
+				return mt.getDataImpl(mock, "replaced-data")
+			},
+		},
 	}
 
 	for name, tc := range tests {