go/analysis/passes/copylock/copylock.go - tools - Git at Google

 // Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 // Package copylock defines an Analyzer that checks for locks
 // erroneously passed by value.
 package copylock

 import (
 	"bytes"
 	"fmt"
 	"go/ast"
 	"go/token"
 	"go/types"

 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/analysis/passes/inspect"
 	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
 	"golang.org/x/tools/go/ast/inspector"
 )

 const Doc = `check for locks erroneously passed by value

 Inadvertently copying a value containing a lock, such as sync.Mutex or
 sync.WaitGroup, may cause both copies to malfunction. Generally such
 values should be referred to through a pointer.`

 var Analyzer = &analysis.Analyzer{
 	Name:             "copylocks",
 	Doc:              Doc,
 	Requires:         []*analysis.Analyzer{inspect.Analyzer},
 	RunDespiteErrors: true,
 	Run:              run,
 }

 func run(pass *analysis.Pass) (interface{}, error) {
 	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

 	nodeFilter := []ast.Node{
 		(*ast.AssignStmt)(nil),
 		(*ast.CallExpr)(nil),
 		(*ast.CompositeLit)(nil),
 		(*ast.FuncDecl)(nil),
 		(*ast.FuncLit)(nil),
 		(*ast.GenDecl)(nil),
 		(*ast.RangeStmt)(nil),
 		(*ast.ReturnStmt)(nil),
 	}
 	inspect.Preorder(nodeFilter, func(node ast.Node) {
 		switch node := node.(type) {
 		case *ast.RangeStmt:
 			checkCopyLocksRange(pass, node)
 		case *ast.FuncDecl:
 			checkCopyLocksFunc(pass, node.Name.Name, node.Recv, node.Type)
 		case *ast.FuncLit:
 			checkCopyLocksFunc(pass, "func", nil, node.Type)
 		case *ast.CallExpr:
 			checkCopyLocksCallExpr(pass, node)
 		case *ast.AssignStmt:
 			checkCopyLocksAssign(pass, node)
 		case *ast.GenDecl:
 			checkCopyLocksGenDecl(pass, node)
 		case *ast.CompositeLit:
 			checkCopyLocksCompositeLit(pass, node)
 		case *ast.ReturnStmt:
 			checkCopyLocksReturnStmt(pass, node)
 		}
 	})
 	return nil, nil
 }

 // checkCopyLocksAssign checks whether an assignment
 // copies a lock.
 func checkCopyLocksAssign(pass *analysis.Pass, as *ast.AssignStmt) {
 	for i, x := range as.Rhs {
 		if path := lockPathRhs(pass, x); path != nil {
 			pass.ReportRangef(x, "assignment copies lock value to %v: %v", analysisutil.Format(pass.Fset, as.Lhs[i]), path)
 		}
 	}
 }

 // checkCopyLocksGenDecl checks whether lock is copied
 // in variable declaration.
 func checkCopyLocksGenDecl(pass *analysis.Pass, gd *ast.GenDecl) {
 	if gd.Tok != token.VAR {
 		return
 	}
 	for _, spec := range gd.Specs {
 		valueSpec := spec.(*ast.ValueSpec)
 		for i, x := range valueSpec.Values {
 			if path := lockPathRhs(pass, x); path != nil {
 				pass.ReportRangef(x, "variable declaration copies lock value to %v: %v", valueSpec.Names[i].Name, path)
 			}
 		}
 	}
 }

 // checkCopyLocksCompositeLit detects lock copy inside a composite literal
 func checkCopyLocksCompositeLit(pass *analysis.Pass, cl *ast.CompositeLit) {
 	for _, x := range cl.Elts {
 		if node, ok := x.(*ast.KeyValueExpr); ok {
 			x = node.Value
 		}
 		if path := lockPathRhs(pass, x); path != nil {
 			pass.ReportRangef(x, "literal copies lock value from %v: %v", analysisutil.Format(pass.Fset, x), path)
 		}
 	}
 }

 // checkCopyLocksReturnStmt detects lock copy in return statement
 func checkCopyLocksReturnStmt(pass *analysis.Pass, rs *ast.ReturnStmt) {
 	for _, x := range rs.Results {
 		if path := lockPathRhs(pass, x); path != nil {
 			pass.ReportRangef(x, "return copies lock value: %v", path)
 		}
 	}
 }

 // checkCopyLocksCallExpr detects lock copy in the arguments to a function call
 func checkCopyLocksCallExpr(pass *analysis.Pass, ce *ast.CallExpr) {
 	var id *ast.Ident
 	switch fun := ce.Fun.(type) {
 	case *ast.Ident:
 		id = fun
 	case *ast.SelectorExpr:
 		id = fun.Sel
 	}
 	if fun, ok := pass.TypesInfo.Uses[id].(*types.Builtin); ok {
 		switch fun.Name() {
 		case "new", "len", "cap", "Sizeof":
 			return
 		}
 	}
 	for _, x := range ce.Args {
 		if path := lockPathRhs(pass, x); path != nil {
 			pass.ReportRangef(x, "call of %s copies lock value: %v", analysisutil.Format(pass.Fset, ce.Fun), path)
 		}
 	}
 }

 // checkCopyLocksFunc checks whether a function might
 // inadvertently copy a lock, by checking whether
 // its receiver, parameters, or return values
 // are locks.
 func checkCopyLocksFunc(pass *analysis.Pass, name string, recv *ast.FieldList, typ *ast.FuncType) {
 	if recv != nil && len(recv.List) > 0 {
 		expr := recv.List[0].Type
 		if path := lockPath(pass.Pkg, pass.TypesInfo.Types[expr].Type); path != nil {
 			pass.ReportRangef(expr, "%s passes lock by value: %v", name, path)
 		}
 	}

 	if typ.Params != nil {
 		for _, field := range typ.Params.List {
 			expr := field.Type
 			if path := lockPath(pass.Pkg, pass.TypesInfo.Types[expr].Type); path != nil {
 				pass.ReportRangef(expr, "%s passes lock by value: %v", name, path)
 			}
 		}
 	}

 	// Don't check typ.Results. If T has a Lock field it's OK to write
 	//     return T{}
 	// because that is returning the zero value. Leave result checking
 	// to the return statement.
 }

 // checkCopyLocksRange checks whether a range statement
 // might inadvertently copy a lock by checking whether
 // any of the range variables are locks.
 func checkCopyLocksRange(pass *analysis.Pass, r *ast.RangeStmt) {
 	checkCopyLocksRangeVar(pass, r.Tok, r.Key)
 	checkCopyLocksRangeVar(pass, r.Tok, r.Value)
 }

 func checkCopyLocksRangeVar(pass *analysis.Pass, rtok token.Token, e ast.Expr) {
 	if e == nil {
 		return
 	}
 	id, isId := e.(*ast.Ident)
 	if isId && id.Name == "_" {
 		return
 	}

 	var typ types.Type
 	if rtok == token.DEFINE {
 		if !isId {
 			return
 		}
 		obj := pass.TypesInfo.Defs[id]
 		if obj == nil {
 			return
 		}
 		typ = obj.Type()
 	} else {
 		typ = pass.TypesInfo.Types[e].Type
 	}

 	if typ == nil {
 		return
 	}
 	if path := lockPath(pass.Pkg, typ); path != nil {
 		pass.Reportf(e.Pos(), "range var %s copies lock: %v", analysisutil.Format(pass.Fset, e), path)
 	}
 }

 type typePath []types.Type

 // String pretty-prints a typePath.
 func (path typePath) String() string {
 	n := len(path)
 	var buf bytes.Buffer
 	for i := range path {
 		if i > 0 {
 			fmt.Fprint(&buf, " contains ")
 		}
 		// The human-readable path is in reverse order, outermost to innermost.
 		fmt.Fprint(&buf, path[n-i-1].String())
 	}
 	return buf.String()
 }

 func lockPathRhs(pass *analysis.Pass, x ast.Expr) typePath {
 	if _, ok := x.(*ast.CompositeLit); ok {
 		return nil
 	}
 	if _, ok := x.(*ast.CallExpr); ok {
 		// A call may return a zero value.
 		return nil
 	}
 	if star, ok := x.(*ast.StarExpr); ok {
 		if _, ok := star.X.(*ast.CallExpr); ok {
 			// A call may return a pointer to a zero value.
 			return nil
 		}
 	}
 	return lockPath(pass.Pkg, pass.TypesInfo.Types[x].Type)
 }

 // lockPath returns a typePath describing the location of a lock value
 // contained in typ. If there is no contained lock, it returns nil.
 func lockPath(tpkg *types.Package, typ types.Type) typePath {
 	if typ == nil {
 		return nil
 	}

 	for {
 		atyp, ok := typ.Underlying().(*types.Array)
 		if !ok {
 			break
 		}
 		typ = atyp.Elem()
 	}

 	// We're only interested in the case in which the underlying
 	// type is a struct. (Interfaces and pointers are safe to copy.)
 	styp, ok := typ.Underlying().(*types.Struct)
 	if !ok {
 		return nil
 	}

 	// We're looking for cases in which a pointer to this type
 	// is a sync.Locker, but a value is not. This differentiates
 	// embedded interfaces from embedded values.
 	if types.Implements(types.NewPointer(typ), lockerType) && !types.Implements(typ, lockerType) {
 		return []types.Type{typ}
 	}

 	// In go1.10, sync.noCopy did not implement Locker.
 	// (The Unlock method was added only in CL 121876.)
 	// TODO(adonovan): remove workaround when we drop go1.10.
 	if named, ok := typ.(*types.Named); ok &&
 		named.Obj().Name() == "noCopy" &&
 		named.Obj().Pkg().Path() == "sync" {
 		return []types.Type{typ}
 	}

 	nfields := styp.NumFields()
 	for i := 0; i < nfields; i++ {
 		ftyp := styp.Field(i).Type()
 		subpath := lockPath(tpkg, ftyp)
 		if subpath != nil {
 			return append(subpath, typ)
 		}
 	}

 	return nil
 }

 var lockerType *types.Interface

 // Construct a sync.Locker interface type.
 func init() {
 	nullary := types.NewSignature(nil, nil, nil, false) // func()
 	methods := []*types.Func{
 		types.NewFunc(token.NoPos, nil, "Lock", nullary),
 		types.NewFunc(token.NoPos, nil, "Unlock", nullary),
 	}
 	lockerType = types.NewInterface(methods, nil).Complete()
 }
	// Copyright 2013 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	// Package copylock defines an Analyzer that checks for locks
	// erroneously passed by value.
	package copylock

	import (
	"bytes"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
	"golang.org/x/tools/go/ast/inspector"
	)

	const Doc = `check for locks erroneously passed by value

	Inadvertently copying a value containing a lock, such as sync.Mutex or
	sync.WaitGroup, may cause both copies to malfunction. Generally such
	values should be referred to through a pointer.`

	var Analyzer = &analysis.Analyzer{
	Name: "copylocks",
	Doc: Doc,
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	RunDespiteErrors: true,
	Run: run,
	}

	func run(pass *analysis.Pass) (interface{}, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
	(*ast.AssignStmt)(nil),
	(*ast.CallExpr)(nil),
	(*ast.CompositeLit)(nil),
	(*ast.FuncDecl)(nil),
	(*ast.FuncLit)(nil),
	(*ast.GenDecl)(nil),
	(*ast.RangeStmt)(nil),
	(*ast.ReturnStmt)(nil),
	}
	inspect.Preorder(nodeFilter, func(node ast.Node) {
	switch node := node.(type) {
	case *ast.RangeStmt:
	checkCopyLocksRange(pass, node)
	case *ast.FuncDecl:
	checkCopyLocksFunc(pass, node.Name.Name, node.Recv, node.Type)
	case *ast.FuncLit:
	checkCopyLocksFunc(pass, "func", nil, node.Type)
	case *ast.CallExpr:
	checkCopyLocksCallExpr(pass, node)
	case *ast.AssignStmt:
	checkCopyLocksAssign(pass, node)
	case *ast.GenDecl:
	checkCopyLocksGenDecl(pass, node)
	case *ast.CompositeLit:
	checkCopyLocksCompositeLit(pass, node)
	case *ast.ReturnStmt:
	checkCopyLocksReturnStmt(pass, node)
	}
	})
	return nil, nil
	}

	// checkCopyLocksAssign checks whether an assignment
	// copies a lock.
	func checkCopyLocksAssign(pass analysis.Pass, as ast.AssignStmt) {
	for i, x := range as.Rhs {
	if path := lockPathRhs(pass, x); path != nil {
	pass.ReportRangef(x, "assignment copies lock value to %v: %v", analysisutil.Format(pass.Fset, as.Lhs[i]), path)
	}
	}
	}

	// checkCopyLocksGenDecl checks whether lock is copied
	// in variable declaration.
	func checkCopyLocksGenDecl(pass analysis.Pass, gd ast.GenDecl) {
	if gd.Tok != token.VAR {
	return
	}
	for _, spec := range gd.Specs {
	valueSpec := spec.(*ast.ValueSpec)
	for i, x := range valueSpec.Values {
	if path := lockPathRhs(pass, x); path != nil {
	pass.ReportRangef(x, "variable declaration copies lock value to %v: %v", valueSpec.Names[i].Name, path)
	}
	}
	}
	}

	// checkCopyLocksCompositeLit detects lock copy inside a composite literal
	func checkCopyLocksCompositeLit(pass analysis.Pass, cl ast.CompositeLit) {
	for _, x := range cl.Elts {
	if node, ok := x.(*ast.KeyValueExpr); ok {
	x = node.Value
	}
	if path := lockPathRhs(pass, x); path != nil {
	pass.ReportRangef(x, "literal copies lock value from %v: %v", analysisutil.Format(pass.Fset, x), path)
	}
	}
	}

	// checkCopyLocksReturnStmt detects lock copy in return statement
	func checkCopyLocksReturnStmt(pass analysis.Pass, rs ast.ReturnStmt) {
	for _, x := range rs.Results {
	if path := lockPathRhs(pass, x); path != nil {
	pass.ReportRangef(x, "return copies lock value: %v", path)
	}
	}
	}

	// checkCopyLocksCallExpr detects lock copy in the arguments to a function call
	func checkCopyLocksCallExpr(pass analysis.Pass, ce ast.CallExpr) {
	var id *ast.Ident
	switch fun := ce.Fun.(type) {
	case *ast.Ident:
	id = fun
	case *ast.SelectorExpr:
	id = fun.Sel
	}
	if fun, ok := pass.TypesInfo.Uses[id].(*types.Builtin); ok {
	switch fun.Name() {
	case "new", "len", "cap", "Sizeof":
	return
	}
	}
	for _, x := range ce.Args {
	if path := lockPathRhs(pass, x); path != nil {
	pass.ReportRangef(x, "call of %s copies lock value: %v", analysisutil.Format(pass.Fset, ce.Fun), path)
	}
	}
	}

	// checkCopyLocksFunc checks whether a function might
	// inadvertently copy a lock, by checking whether
	// its receiver, parameters, or return values
	// are locks.
	func checkCopyLocksFunc(pass analysis.Pass, name string, recv ast.FieldList, typ *ast.FuncType) {
	if recv != nil && len(recv.List) > 0 {
	expr := recv.List[0].Type
	if path := lockPath(pass.Pkg, pass.TypesInfo.Types[expr].Type); path != nil {
	pass.ReportRangef(expr, "%s passes lock by value: %v", name, path)
	}
	}

	if typ.Params != nil {
	for _, field := range typ.Params.List {
	expr := field.Type
	if path := lockPath(pass.Pkg, pass.TypesInfo.Types[expr].Type); path != nil {
	pass.ReportRangef(expr, "%s passes lock by value: %v", name, path)
	}
	}
	}

	// Don't check typ.Results. If T has a Lock field it's OK to write
	// return T{}
	// because that is returning the zero value. Leave result checking
	// to the return statement.
	}

	// checkCopyLocksRange checks whether a range statement
	// might inadvertently copy a lock by checking whether
	// any of the range variables are locks.
	func checkCopyLocksRange(pass analysis.Pass, r ast.RangeStmt) {
	checkCopyLocksRangeVar(pass, r.Tok, r.Key)
	checkCopyLocksRangeVar(pass, r.Tok, r.Value)
	}

	func checkCopyLocksRangeVar(pass *analysis.Pass, rtok token.Token, e ast.Expr) {
	if e == nil {
	return
	}
	id, isId := e.(*ast.Ident)
	if isId && id.Name == "_" {
	return
	}

	var typ types.Type
	if rtok == token.DEFINE {
	if !isId {
	return
	}
	obj := pass.TypesInfo.Defs[id]
	if obj == nil {
	return
	}
	typ = obj.Type()
	} else {
	typ = pass.TypesInfo.Types[e].Type
	}

	if typ == nil {
	return
	}
	if path := lockPath(pass.Pkg, typ); path != nil {
	pass.Reportf(e.Pos(), "range var %s copies lock: %v", analysisutil.Format(pass.Fset, e), path)
	}
	}

	type typePath []types.Type

	// String pretty-prints a typePath.
	func (path typePath) String() string {
	n := len(path)
	var buf bytes.Buffer
	for i := range path {
	if i > 0 {
	fmt.Fprint(&buf, " contains ")
	}
	// The human-readable path is in reverse order, outermost to innermost.
	fmt.Fprint(&buf, path[n-i-1].String())
	}
	return buf.String()
	}

	func lockPathRhs(pass *analysis.Pass, x ast.Expr) typePath {
	if _, ok := x.(*ast.CompositeLit); ok {
	return nil
	}
	if _, ok := x.(*ast.CallExpr); ok {
	// A call may return a zero value.
	return nil
	}
	if star, ok := x.(*ast.StarExpr); ok {
	if _, ok := star.X.(*ast.CallExpr); ok {
	// A call may return a pointer to a zero value.
	return nil
	}
	}
	return lockPath(pass.Pkg, pass.TypesInfo.Types[x].Type)
	}

	// lockPath returns a typePath describing the location of a lock value
	// contained in typ. If there is no contained lock, it returns nil.
	func lockPath(tpkg *types.Package, typ types.Type) typePath {
	if typ == nil {
	return nil
	}

	for {
	atyp, ok := typ.Underlying().(*types.Array)
	if !ok {
	break
	}
	typ = atyp.Elem()
	}

	// We're only interested in the case in which the underlying
	// type is a struct. (Interfaces and pointers are safe to copy.)
	styp, ok := typ.Underlying().(*types.Struct)
	if !ok {
	return nil
	}

	// We're looking for cases in which a pointer to this type
	// is a sync.Locker, but a value is not. This differentiates
	// embedded interfaces from embedded values.
	if types.Implements(types.NewPointer(typ), lockerType) && !types.Implements(typ, lockerType) {
	return []types.Type{typ}
	}

	// In go1.10, sync.noCopy did not implement Locker.
	// (The Unlock method was added only in CL 121876.)
	// TODO(adonovan): remove workaround when we drop go1.10.
	if named, ok := typ.(*types.Named); ok &&
	named.Obj().Name() == "noCopy" &&
	named.Obj().Pkg().Path() == "sync" {
	return []types.Type{typ}
	}

	nfields := styp.NumFields()
	for i := 0; i < nfields; i++ {
	ftyp := styp.Field(i).Type()
	subpath := lockPath(tpkg, ftyp)
	if subpath != nil {
	return append(subpath, typ)
	}
	}

	return nil
	}

	var lockerType *types.Interface

	// Construct a sync.Locker interface type.
	func init() {
	nullary := types.NewSignature(nil, nil, nil, false) // func()
	methods := []*types.Func{
	types.NewFunc(token.NoPos, nil, "Lock", nullary),
	types.NewFunc(token.NoPos, nil, "Unlock", nullary),
	}
	lockerType = types.NewInterface(methods, nil).Complete()
	}