initial working build of custom linter

Signed-off-by: Will Murphy <will.murphy@anchore.com>

test/linters/ensuredefer/analyzer.go

@@ -0,0 +1,85 @@
+package ensuredefer
+
+import (
+	"github.com/golangci/plugin-module-register/register"
+	"go/ast"
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+func init() {
+	register.Plugin("ensuredefer", func(conf any) (register.LinterPlugin, error) {
+		return &analyzerPlugin{}, nil
+	})
+}
+
+func run(pass *analysis.Pass) (any, error) {
+	insp := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+	nodeFilter := []ast.Node{
+		(*ast.ExprStmt)(nil),
+		(*ast.DeferStmt)(nil),
+	}
+	insp.Preorder(nodeFilter, func(node ast.Node) {
+		// if we have a *ast.ExprStmt that calls internal.CloseAndLogError, report a problem.
+		// (if the function is correctly called in a defer statement, the block will have
+		switch t := node.(type) {
+		case *ast.ExprStmt:
+			if !isExprStmtAllowed(t, pass) {
+				pass.Reportf(t.Pos(), "internal.CloseAndLogError must be called in defer")
+			}
+		}
+	})
+	return nil, nil
+}
+
+func isExprStmtAllowed(e *ast.ExprStmt, pass *analysis.Pass) bool {
+	call, ok := e.X.(*ast.CallExpr)
+	if !ok {
+		return true
+	}
+	sel, ok := call.Fun.(*ast.SelectorExpr)
+	if !ok {
+		return true
+	}
+
+	obj := pass.TypesInfo.Uses[sel.Sel]
+	if obj == nil {
+		return true
+	}
+	pkg := obj.Pkg()
+	if pkg == nil {
+		return true
+	}
+
+	if pkg.Path() == "github.com/anchore/syft/internal" && sel.Sel.Name == "CloseAndLogError" {
+		return false
+	}
+
+	return true
+}
+
+func NewAnalyzer() *analysis.Analyzer {
+	analyzer := analysis.Analyzer{
+		Name:     "ensuredefer",
+		Doc:      "enforce that specified functions are called in defer statements",
+		Run:      run,
+		Requires: []*analysis.Analyzer{inspect.Analyzer},
+	}
+	return &analyzer
+}
+
+var analyzerInstance = NewAnalyzer()
+
+type analyzerPlugin struct{}
+
+func (p *analyzerPlugin) BuildAnalyzers() ([]*analysis.Analyzer, error) {
+	return []*analysis.Analyzer{
+		analyzerInstance,
+	}, nil
+}
+
+func (p *analyzerPlugin) GetLoadMode() string {
+	//TODO: what does this do
+	return register.LoadModeSyntax
+}

test/linters/ensuredefer/main.go

@@ -0,0 +1,9 @@
+package ensuredefer
+
+import (
+	"golang.org/x/tools/go/analysis/singlechecker"
+)
+
+func main() {
+	singlechecker.Main(NewAnalyzer())
+}