+++ /dev/null
-// 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()
-}
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