Update linter CI and fix lint errors

.github/workflows/ci.yml

@@ -106,6 +106,6 @@ jobs:
         go-version: '1.23.3'
 
     - name: Run linter
-      uses: golangci/golangci-lint-action@v4
+      uses: golangci/golangci-lint-action@v9
       with:
-        version: latest
+        version: v2.6.1

.golangci.yml

@@ -0,0 +1,12 @@
+version: "2"
+
+run:
+  timeout: 5m
+  tests: true
+
+linters:
+  default: standard
+  settings:
+    govet:
+      disable:
+        - unsafeptr

Makefile

@@ -39,7 +39,7 @@ lint:
 	golangci-lint run ./...
 
 deps:
-	go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest
+	go install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@v2.6.1
 
 update-kernel:
 	git subtree pull --prefix=depend/bitcoin https://github.com/bitcoin/bitcoin.git master --squash

kernel/chainstate_manager_test.go

@@ -143,7 +143,11 @@ func (s *ChainstateManagerTestSuite) Setup(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to create temp dir: %v", err)
 	}
-	t.Cleanup(func() { os.RemoveAll(tempDir) })
+	t.Cleanup(func() {
+		if err := os.RemoveAll(tempDir); err != nil {
+			t.Errorf("Failed to remove temp dir: %v", err)
+		}
+	})
 
 	dataDir := filepath.Join(tempDir, "data")
 	blocksDir := filepath.Join(tempDir, "blocks")

kernel/context.go

@@ -53,7 +53,7 @@ func NewContext(options *ContextOptions) (*Context, error) {
 //
 // Returns an error if the interrupt signal cannot be delivered.
 func (ctx *Context) Interrupt() error {
-	result := C.btck_context_interrupt((*C.btck_Context)(ctx.handle.ptr))
+	result := C.btck_context_interrupt((*C.btck_Context)(ctx.ptr))
 	if result != 0 {
 		return &InternalError{"Context interrupt failed"}
 	}
@@ -65,5 +65,5 @@ func (ctx *Context) Interrupt() error {
 // The context is reference-counted internally, so this operation is efficient and does
 // not duplicate the underlying data.
 func (ctx *Context) Copy() *Context {
-	return newContext((*C.btck_Context)(ctx.handle.ptr), false)
+	return newContext((*C.btck_Context)(ctx.ptr), false)
 }