1 // Copyright 2013 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package main 6 7 import ( 8 "go/ast" 9 "go/token" 10 ) 11 12 func init() { 13 register("atomic", 14 "check for common mistaken usages of the sync/atomic package", 15 checkAtomicAssignment, 16 assignStmt) 17 } 18 19 // checkAtomicAssignment walks the assignment statement checking for common 20 // mistaken usage of atomic package, such as: x = atomic.AddUint64(&x, 1) 21 func checkAtomicAssignment(f *File, node ast.Node) { 22 n := node.(*ast.AssignStmt) 23 if len(n.Lhs) != len(n.Rhs) { 24 return 25 } 26 27 for i, right := range n.Rhs { 28 call, ok := right.(*ast.CallExpr) 29 if !ok { 30 continue 31 } 32 sel, ok := call.Fun.(*ast.SelectorExpr) 33 if !ok { 34 continue 35 } 36 pkg, ok := sel.X.(*ast.Ident) 37 if !ok || pkg.Name != "atomic" { 38 continue 39 } 40 41 switch sel.Sel.Name { 42 case "AddInt32", "AddInt64", "AddUint32", "AddUint64", "AddUintptr": 43 f.checkAtomicAddAssignment(n.Lhs[i], call) 44 } 45 } 46 } 47 48 // checkAtomicAddAssignment walks the atomic.Add* method calls checking for assigning the return value 49 // to the same variable being used in the operation 50 func (f *File) checkAtomicAddAssignment(left ast.Expr, call *ast.CallExpr) { 51 if len(call.Args) != 2 { 52 return 53 } 54 arg := call.Args[0] 55 broken := false 56 57 if uarg, ok := arg.(*ast.UnaryExpr); ok && uarg.Op == token.AND { 58 broken = f.gofmt(left) == f.gofmt(uarg.X) 59 } else if star, ok := left.(*ast.StarExpr); ok { 60 broken = f.gofmt(star.X) == f.gofmt(arg) 61 } 62 63 if broken { 64 f.Bad(left.Pos(), "direct assignment to atomic value") 65 } 66 } 67
