| // Copyright 2010 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 printf |
| |
| import ( |
| "bytes" |
| _ "embed" |
| "fmt" |
| "go/ast" |
| "go/constant" |
| "go/token" |
| "go/types" |
| "reflect" |
| "regexp" |
| "sort" |
| "strconv" |
| "strings" |
| "unicode/utf8" |
| |
| "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" |
| "golang.org/x/tools/go/types/typeutil" |
| "golang.org/x/tools/internal/typeparams" |
| ) |
| |
| func init() { |
| Analyzer.Flags.Var(isPrint, "funcs", "comma-separated list of print function names to check") |
| } |
| |
| //go:embed doc.go |
| var doc string |
| |
| var Analyzer = &analysis.Analyzer{ |
| Name: "printf", |
| Doc: analysisutil.MustExtractDoc(doc, "printf"), |
| URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/printf", |
| Requires: []*analysis.Analyzer{inspect.Analyzer}, |
| Run: run, |
| ResultType: reflect.TypeOf((*Result)(nil)), |
| FactTypes: []analysis.Fact{new(isWrapper)}, |
| } |
| |
| // Kind is a kind of fmt function behavior. |
| type Kind int |
| |
| const ( |
| KindNone Kind = iota // not a fmt wrapper function |
| KindPrint // function behaves like fmt.Print |
| KindPrintf // function behaves like fmt.Printf |
| KindErrorf // function behaves like fmt.Errorf |
| ) |
| |
| func (kind Kind) String() string { |
| switch kind { |
| case KindPrint: |
| return "print" |
| case KindPrintf: |
| return "printf" |
| case KindErrorf: |
| return "errorf" |
| } |
| return "" |
| } |
| |
| // Result is the printf analyzer's result type. Clients may query the result |
| // to learn whether a function behaves like fmt.Print or fmt.Printf. |
| type Result struct { |
| funcs map[*types.Func]Kind |
| } |
| |
| // Kind reports whether fn behaves like fmt.Print or fmt.Printf. |
| func (r *Result) Kind(fn *types.Func) Kind { |
| _, ok := isPrint[fn.FullName()] |
| if !ok { |
| // Next look up just "printf", for use with -printf.funcs. |
| _, ok = isPrint[strings.ToLower(fn.Name())] |
| } |
| if ok { |
| if strings.HasSuffix(fn.Name(), "f") { |
| return KindPrintf |
| } else { |
| return KindPrint |
| } |
| } |
| |
| return r.funcs[fn] |
| } |
| |
| // isWrapper is a fact indicating that a function is a print or printf wrapper. |
| type isWrapper struct{ Kind Kind } |
| |
| func (f *isWrapper) AFact() {} |
| |
| func (f *isWrapper) String() string { |
| switch f.Kind { |
| case KindPrintf: |
| return "printfWrapper" |
| case KindPrint: |
| return "printWrapper" |
| case KindErrorf: |
| return "errorfWrapper" |
| default: |
| return "unknownWrapper" |
| } |
| } |
| |
| func run(pass *analysis.Pass) (interface{}, error) { |
| res := &Result{ |
| funcs: make(map[*types.Func]Kind), |
| } |
| findPrintfLike(pass, res) |
| checkCall(pass) |
| return res, nil |
| } |
| |
| type printfWrapper struct { |
| obj *types.Func |
| fdecl *ast.FuncDecl |
| format *types.Var |
| args *types.Var |
| callers []printfCaller |
| failed bool // if true, not a printf wrapper |
| } |
| |
| type printfCaller struct { |
| w *printfWrapper |
| call *ast.CallExpr |
| } |
| |
| // maybePrintfWrapper decides whether decl (a declared function) may be a wrapper |
| // around a fmt.Printf or fmt.Print function. If so it returns a printfWrapper |
| // function describing the declaration. Later processing will analyze the |
| // graph of potential printf wrappers to pick out the ones that are true wrappers. |
| // A function may be a Printf or Print wrapper if its last argument is ...interface{}. |
| // If the next-to-last argument is a string, then this may be a Printf wrapper. |
| // Otherwise it may be a Print wrapper. |
| func maybePrintfWrapper(info *types.Info, decl ast.Decl) *printfWrapper { |
| // Look for functions with final argument type ...interface{}. |
| fdecl, ok := decl.(*ast.FuncDecl) |
| if !ok || fdecl.Body == nil { |
| return nil |
| } |
| fn, ok := info.Defs[fdecl.Name].(*types.Func) |
| // Type information may be incomplete. |
| if !ok { |
| return nil |
| } |
| |
| sig := fn.Type().(*types.Signature) |
| if !sig.Variadic() { |
| return nil // not variadic |
| } |
| |
| params := sig.Params() |
| nparams := params.Len() // variadic => nonzero |
| |
| args := params.At(nparams - 1) |
| iface, ok := args.Type().(*types.Slice).Elem().(*types.Interface) |
| if !ok || !iface.Empty() { |
| return nil // final (args) param is not ...interface{} |
| } |
| |
| // Is second last param 'format string'? |
| var format *types.Var |
| if nparams >= 2 { |
| if p := params.At(nparams - 2); p.Type() == types.Typ[types.String] { |
| format = p |
| } |
| } |
| |
| return &printfWrapper{ |
| obj: fn, |
| fdecl: fdecl, |
| format: format, |
| args: args, |
| } |
| } |
| |
| // findPrintfLike scans the entire package to find printf-like functions. |
| func findPrintfLike(pass *analysis.Pass, res *Result) (interface{}, error) { |
| // Gather potential wrappers and call graph between them. |
| byObj := make(map[*types.Func]*printfWrapper) |
| var wrappers []*printfWrapper |
| for _, file := range pass.Files { |
| for _, decl := range file.Decls { |
| w := maybePrintfWrapper(pass.TypesInfo, decl) |
| if w == nil { |
| continue |
| } |
| byObj[w.obj] = w |
| wrappers = append(wrappers, w) |
| } |
| } |
| |
| // Walk the graph to figure out which are really printf wrappers. |
| for _, w := range wrappers { |
| // Scan function for calls that could be to other printf-like functions. |
| ast.Inspect(w.fdecl.Body, func(n ast.Node) bool { |
| if w.failed { |
| return false |
| } |
| |
| // TODO: Relax these checks; issue 26555. |
| if assign, ok := n.(*ast.AssignStmt); ok { |
| for _, lhs := range assign.Lhs { |
| if match(pass.TypesInfo, lhs, w.format) || |
| match(pass.TypesInfo, lhs, w.args) { |
| // Modifies the format |
| // string or args in |
| // some way, so not a |
| // simple wrapper. |
| w.failed = true |
| return false |
| } |
| } |
| } |
| if un, ok := n.(*ast.UnaryExpr); ok && un.Op == token.AND { |
| if match(pass.TypesInfo, un.X, w.format) || |
| match(pass.TypesInfo, un.X, w.args) { |
| // Taking the address of the |
| // format string or args, |
| // so not a simple wrapper. |
| w.failed = true |
| return false |
| } |
| } |
| |
| call, ok := n.(*ast.CallExpr) |
| if !ok || len(call.Args) == 0 || !match(pass.TypesInfo, call.Args[len(call.Args)-1], w.args) { |
| return true |
| } |
| |
| fn, kind := printfNameAndKind(pass, call) |
| if kind != 0 { |
| checkPrintfFwd(pass, w, call, kind, res) |
| return true |
| } |
| |
| // If the call is to another function in this package, |
| // maybe we will find out it is printf-like later. |
| // Remember this call for later checking. |
| if fn != nil && fn.Pkg() == pass.Pkg && byObj[fn] != nil { |
| callee := byObj[fn] |
| callee.callers = append(callee.callers, printfCaller{w, call}) |
| } |
| |
| return true |
| }) |
| } |
| return nil, nil |
| } |
| |
| func match(info *types.Info, arg ast.Expr, param *types.Var) bool { |
| id, ok := arg.(*ast.Ident) |
| return ok && info.ObjectOf(id) == param |
| } |
| |
| // checkPrintfFwd checks that a printf-forwarding wrapper is forwarding correctly. |
| // It diagnoses writing fmt.Printf(format, args) instead of fmt.Printf(format, args...). |
| func checkPrintfFwd(pass *analysis.Pass, w *printfWrapper, call *ast.CallExpr, kind Kind, res *Result) { |
| matched := kind == KindPrint || |
| kind != KindNone && len(call.Args) >= 2 && match(pass.TypesInfo, call.Args[len(call.Args)-2], w.format) |
| if !matched { |
| return |
| } |
| |
| if !call.Ellipsis.IsValid() { |
| typ, ok := pass.TypesInfo.Types[call.Fun].Type.(*types.Signature) |
| if !ok { |
| return |
| } |
| if len(call.Args) > typ.Params().Len() { |
| // If we're passing more arguments than what the |
| // print/printf function can take, adding an ellipsis |
| // would break the program. For example: |
| // |
| // func foo(arg1 string, arg2 ...interface{}) { |
| // fmt.Printf("%s %v", arg1, arg2) |
| // } |
| return |
| } |
| desc := "printf" |
| if kind == KindPrint { |
| desc = "print" |
| } |
| pass.ReportRangef(call, "missing ... in args forwarded to %s-like function", desc) |
| return |
| } |
| fn := w.obj |
| var fact isWrapper |
| if !pass.ImportObjectFact(fn, &fact) { |
| fact.Kind = kind |
| pass.ExportObjectFact(fn, &fact) |
| res.funcs[fn] = kind |
| for _, caller := range w.callers { |
| checkPrintfFwd(pass, caller.w, caller.call, kind, res) |
| } |
| } |
| } |
| |
| // isPrint records the print functions. |
| // If a key ends in 'f' then it is assumed to be a formatted print. |
| // |
| // Keys are either values returned by (*types.Func).FullName, |
| // or case-insensitive identifiers such as "errorf". |
| // |
| // The -funcs flag adds to this set. |
| // |
| // The set below includes facts for many important standard library |
| // functions, even though the analysis is capable of deducing that, for |
| // example, fmt.Printf forwards to fmt.Fprintf. We avoid relying on the |
| // driver applying analyzers to standard packages because "go vet" does |
| // not do so with gccgo, and nor do some other build systems. |
| var isPrint = stringSet{ |
| "fmt.Appendf": true, |
| "fmt.Append": true, |
| "fmt.Appendln": true, |
| "fmt.Errorf": true, |
| "fmt.Fprint": true, |
| "fmt.Fprintf": true, |
| "fmt.Fprintln": true, |
| "fmt.Print": true, |
| "fmt.Printf": true, |
| "fmt.Println": true, |
| "fmt.Sprint": true, |
| "fmt.Sprintf": true, |
| "fmt.Sprintln": true, |
| |
| "runtime/trace.Logf": true, |
| |
| "log.Print": true, |
| "log.Printf": true, |
| "log.Println": true, |
| "log.Fatal": true, |
| "log.Fatalf": true, |
| "log.Fatalln": true, |
| "log.Panic": true, |
| "log.Panicf": true, |
| "log.Panicln": true, |
| "(*log.Logger).Fatal": true, |
| "(*log.Logger).Fatalf": true, |
| "(*log.Logger).Fatalln": true, |
| "(*log.Logger).Panic": true, |
| "(*log.Logger).Panicf": true, |
| "(*log.Logger).Panicln": true, |
| "(*log.Logger).Print": true, |
| "(*log.Logger).Printf": true, |
| "(*log.Logger).Println": true, |
| |
| "(*testing.common).Error": true, |
| "(*testing.common).Errorf": true, |
| "(*testing.common).Fatal": true, |
| "(*testing.common).Fatalf": true, |
| "(*testing.common).Log": true, |
| "(*testing.common).Logf": true, |
| "(*testing.common).Skip": true, |
| "(*testing.common).Skipf": true, |
| // *testing.T and B are detected by induction, but testing.TB is |
| // an interface and the inference can't follow dynamic calls. |
| "(testing.TB).Error": true, |
| "(testing.TB).Errorf": true, |
| "(testing.TB).Fatal": true, |
| "(testing.TB).Fatalf": true, |
| "(testing.TB).Log": true, |
| "(testing.TB).Logf": true, |
| "(testing.TB).Skip": true, |
| "(testing.TB).Skipf": true, |
| } |
| |
| // formatString returns the format string argument and its index within |
| // the given printf-like call expression. |
| // |
| // The last parameter before variadic arguments is assumed to be |
| // a format string. |
| // |
| // The first string literal or string constant is assumed to be a format string |
| // if the call's signature cannot be determined. |
| // |
| // If it cannot find any format string parameter, it returns ("", -1). |
| func formatString(pass *analysis.Pass, call *ast.CallExpr) (format string, idx int) { |
| typ := pass.TypesInfo.Types[call.Fun].Type |
| if typ != nil { |
| if sig, ok := typ.(*types.Signature); ok { |
| if !sig.Variadic() { |
| // Skip checking non-variadic functions. |
| return "", -1 |
| } |
| idx := sig.Params().Len() - 2 |
| if idx < 0 { |
| // Skip checking variadic functions without |
| // fixed arguments. |
| return "", -1 |
| } |
| s, ok := stringConstantArg(pass, call, idx) |
| if !ok { |
| // The last argument before variadic args isn't a string. |
| return "", -1 |
| } |
| return s, idx |
| } |
| } |
| |
| // Cannot determine call's signature. Fall back to scanning for the first |
| // string constant in the call. |
| for idx := range call.Args { |
| if s, ok := stringConstantArg(pass, call, idx); ok { |
| return s, idx |
| } |
| if pass.TypesInfo.Types[call.Args[idx]].Type == types.Typ[types.String] { |
| // Skip checking a call with a non-constant format |
| // string argument, since its contents are unavailable |
| // for validation. |
| return "", -1 |
| } |
| } |
| return "", -1 |
| } |
| |
| // stringConstantArg returns call's string constant argument at the index idx. |
| // |
| // ("", false) is returned if call's argument at the index idx isn't a string |
| // constant. |
| func stringConstantArg(pass *analysis.Pass, call *ast.CallExpr, idx int) (string, bool) { |
| if idx >= len(call.Args) { |
| return "", false |
| } |
| return stringConstantExpr(pass, call.Args[idx]) |
| } |
| |
| // stringConstantExpr returns expression's string constant value. |
| // |
| // ("", false) is returned if expression isn't a string |
| // constant. |
| func stringConstantExpr(pass *analysis.Pass, expr ast.Expr) (string, bool) { |
| lit := pass.TypesInfo.Types[expr].Value |
| if lit != nil && lit.Kind() == constant.String { |
| return constant.StringVal(lit), true |
| } |
| return "", false |
| } |
| |
| // checkCall triggers the print-specific checks if the call invokes a print function. |
| func checkCall(pass *analysis.Pass) { |
| inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector) |
| nodeFilter := []ast.Node{ |
| (*ast.CallExpr)(nil), |
| } |
| inspect.Preorder(nodeFilter, func(n ast.Node) { |
| call := n.(*ast.CallExpr) |
| fn, kind := printfNameAndKind(pass, call) |
| switch kind { |
| case KindPrintf, KindErrorf: |
| checkPrintf(pass, kind, call, fn) |
| case KindPrint: |
| checkPrint(pass, call, fn) |
| } |
| }) |
| } |
| |
| func printfNameAndKind(pass *analysis.Pass, call *ast.CallExpr) (fn *types.Func, kind Kind) { |
| fn, _ = typeutil.Callee(pass.TypesInfo, call).(*types.Func) |
| if fn == nil { |
| return nil, 0 |
| } |
| |
| _, ok := isPrint[fn.FullName()] |
| if !ok { |
| // Next look up just "printf", for use with -printf.funcs. |
| _, ok = isPrint[strings.ToLower(fn.Name())] |
| } |
| if ok { |
| if fn.FullName() == "fmt.Errorf" { |
| kind = KindErrorf |
| } else if strings.HasSuffix(fn.Name(), "f") { |
| kind = KindPrintf |
| } else { |
| kind = KindPrint |
| } |
| return fn, kind |
| } |
| |
| var fact isWrapper |
| if pass.ImportObjectFact(fn, &fact) { |
| return fn, fact.Kind |
| } |
| |
| return fn, KindNone |
| } |
| |
| // isFormatter reports whether t could satisfy fmt.Formatter. |
| // The only interface method to look for is "Format(State, rune)". |
| func isFormatter(typ types.Type) bool { |
| // If the type is an interface, the value it holds might satisfy fmt.Formatter. |
| if _, ok := typ.Underlying().(*types.Interface); ok { |
| // Don't assume type parameters could be formatters. With the greater |
| // expressiveness of constraint interface syntax we expect more type safety |
| // when using type parameters. |
| if !typeparams.IsTypeParam(typ) { |
| return true |
| } |
| } |
| obj, _, _ := types.LookupFieldOrMethod(typ, false, nil, "Format") |
| fn, ok := obj.(*types.Func) |
| if !ok { |
| return false |
| } |
| sig := fn.Type().(*types.Signature) |
| return sig.Params().Len() == 2 && |
| sig.Results().Len() == 0 && |
| isNamed(sig.Params().At(0).Type(), "fmt", "State") && |
| types.Identical(sig.Params().At(1).Type(), types.Typ[types.Rune]) |
| } |
| |
| func isNamed(T types.Type, pkgpath, name string) bool { |
| named, ok := T.(*types.Named) |
| return ok && named.Obj().Pkg().Path() == pkgpath && named.Obj().Name() == name |
| } |
| |
| // formatState holds the parsed representation of a printf directive such as "%3.*[4]d". |
| // It is constructed by parsePrintfVerb. |
| type formatState struct { |
| verb rune // the format verb: 'd' for "%d" |
| format string // the full format directive from % through verb, "%.3d". |
| name string // Printf, Sprintf etc. |
| flags []byte // the list of # + etc. |
| argNums []int // the successive argument numbers that are consumed, adjusted to refer to actual arg in call |
| firstArg int // Index of first argument after the format in the Printf call. |
| // Used only during parse. |
| pass *analysis.Pass |
| call *ast.CallExpr |
| argNum int // Which argument we're expecting to format now. |
| hasIndex bool // Whether the argument is indexed. |
| indexPending bool // Whether we have an indexed argument that has not resolved. |
| nbytes int // number of bytes of the format string consumed. |
| } |
| |
| // checkPrintf checks a call to a formatted print routine such as Printf. |
| func checkPrintf(pass *analysis.Pass, kind Kind, call *ast.CallExpr, fn *types.Func) { |
| format, idx := formatString(pass, call) |
| if idx < 0 { |
| if false { |
| pass.Reportf(call.Lparen, "can't check non-constant format in call to %s", fn.FullName()) |
| } |
| return |
| } |
| |
| firstArg := idx + 1 // Arguments are immediately after format string. |
| if !strings.Contains(format, "%") { |
| if len(call.Args) > firstArg { |
| pass.Reportf(call.Lparen, "%s call has arguments but no formatting directives", fn.FullName()) |
| } |
| return |
| } |
| // Hard part: check formats against args. |
| argNum := firstArg |
| maxArgNum := firstArg |
| anyIndex := false |
| for i, w := 0, 0; i < len(format); i += w { |
| w = 1 |
| if format[i] != '%' { |
| continue |
| } |
| state := parsePrintfVerb(pass, call, fn.FullName(), format[i:], firstArg, argNum) |
| if state == nil { |
| return |
| } |
| w = len(state.format) |
| if !okPrintfArg(pass, call, state) { // One error per format is enough. |
| return |
| } |
| if state.hasIndex { |
| anyIndex = true |
| } |
| if state.verb == 'w' { |
| switch kind { |
| case KindNone, KindPrint, KindPrintf: |
| pass.Reportf(call.Pos(), "%s does not support error-wrapping directive %%w", state.name) |
| return |
| } |
| } |
| if len(state.argNums) > 0 { |
| // Continue with the next sequential argument. |
| argNum = state.argNums[len(state.argNums)-1] + 1 |
| } |
| for _, n := range state.argNums { |
| if n >= maxArgNum { |
| maxArgNum = n + 1 |
| } |
| } |
| } |
| // Dotdotdot is hard. |
| if call.Ellipsis.IsValid() && maxArgNum >= len(call.Args)-1 { |
| return |
| } |
| // If any formats are indexed, extra arguments are ignored. |
| if anyIndex { |
| return |
| } |
| // There should be no leftover arguments. |
| if maxArgNum != len(call.Args) { |
| expect := maxArgNum - firstArg |
| numArgs := len(call.Args) - firstArg |
| pass.ReportRangef(call, "%s call needs %v but has %v", fn.FullName(), count(expect, "arg"), count(numArgs, "arg")) |
| } |
| } |
| |
| // parseFlags accepts any printf flags. |
| func (s *formatState) parseFlags() { |
| for s.nbytes < len(s.format) { |
| switch c := s.format[s.nbytes]; c { |
| case '#', '0', '+', '-', ' ': |
| s.flags = append(s.flags, c) |
| s.nbytes++ |
| default: |
| return |
| } |
| } |
| } |
| |
| // scanNum advances through a decimal number if present. |
| func (s *formatState) scanNum() { |
| for ; s.nbytes < len(s.format); s.nbytes++ { |
| c := s.format[s.nbytes] |
| if c < '0' || '9' < c { |
| return |
| } |
| } |
| } |
| |
| // parseIndex scans an index expression. It returns false if there is a syntax error. |
| func (s *formatState) parseIndex() bool { |
| if s.nbytes == len(s.format) || s.format[s.nbytes] != '[' { |
| return true |
| } |
| // Argument index present. |
| s.nbytes++ // skip '[' |
| start := s.nbytes |
| s.scanNum() |
| ok := true |
| if s.nbytes == len(s.format) || s.nbytes == start || s.format[s.nbytes] != ']' { |
| ok = false // syntax error is either missing "]" or invalid index. |
| s.nbytes = strings.Index(s.format[start:], "]") |
| if s.nbytes < 0 { |
| s.pass.ReportRangef(s.call, "%s format %s is missing closing ]", s.name, s.format) |
| return false |
| } |
| s.nbytes = s.nbytes + start |
| } |
| arg32, err := strconv.ParseInt(s.format[start:s.nbytes], 10, 32) |
| if err != nil || !ok || arg32 <= 0 || arg32 > int64(len(s.call.Args)-s.firstArg) { |
| s.pass.ReportRangef(s.call, "%s format has invalid argument index [%s]", s.name, s.format[start:s.nbytes]) |
| return false |
| } |
| s.nbytes++ // skip ']' |
| arg := int(arg32) |
| arg += s.firstArg - 1 // We want to zero-index the actual arguments. |
| s.argNum = arg |
| s.hasIndex = true |
| s.indexPending = true |
| return true |
| } |
| |
| // parseNum scans a width or precision (or *). It returns false if there's a bad index expression. |
| func (s *formatState) parseNum() bool { |
| if s.nbytes < len(s.format) && s.format[s.nbytes] == '*' { |
| if s.indexPending { // Absorb it. |
| s.indexPending = false |
| } |
| s.nbytes++ |
| s.argNums = append(s.argNums, s.argNum) |
| s.argNum++ |
| } else { |
| s.scanNum() |
| } |
| return true |
| } |
| |
| // parsePrecision scans for a precision. It returns false if there's a bad index expression. |
| func (s *formatState) parsePrecision() bool { |
| // If there's a period, there may be a precision. |
| if s.nbytes < len(s.format) && s.format[s.nbytes] == '.' { |
| s.flags = append(s.flags, '.') // Treat precision as a flag. |
| s.nbytes++ |
| if !s.parseIndex() { |
| return false |
| } |
| if !s.parseNum() { |
| return false |
| } |
| } |
| return true |
| } |
| |
| // parsePrintfVerb looks the formatting directive that begins the format string |
| // and returns a formatState that encodes what the directive wants, without looking |
| // at the actual arguments present in the call. The result is nil if there is an error. |
| func parsePrintfVerb(pass *analysis.Pass, call *ast.CallExpr, name, format string, firstArg, argNum int) *formatState { |
| state := &formatState{ |
| format: format, |
| name: name, |
| flags: make([]byte, 0, 5), |
| argNum: argNum, |
| argNums: make([]int, 0, 1), |
| nbytes: 1, // There's guaranteed to be a percent sign. |
| firstArg: firstArg, |
| pass: pass, |
| call: call, |
| } |
| // There may be flags. |
| state.parseFlags() |
| // There may be an index. |
| if !state.parseIndex() { |
| return nil |
| } |
| // There may be a width. |
| if !state.parseNum() { |
| return nil |
| } |
| // There may be a precision. |
| if !state.parsePrecision() { |
| return nil |
| } |
| // Now a verb, possibly prefixed by an index (which we may already have). |
| if !state.indexPending && !state.parseIndex() { |
| return nil |
| } |
| if state.nbytes == len(state.format) { |
| pass.ReportRangef(call.Fun, "%s format %s is missing verb at end of string", name, state.format) |
| return nil |
| } |
| verb, w := utf8.DecodeRuneInString(state.format[state.nbytes:]) |
| state.verb = verb |
| state.nbytes += w |
| if verb != '%' { |
| state.argNums = append(state.argNums, state.argNum) |
| } |
| state.format = state.format[:state.nbytes] |
| return state |
| } |
| |
| // printfArgType encodes the types of expressions a printf verb accepts. It is a bitmask. |
| type printfArgType int |
| |
| const ( |
| argBool printfArgType = 1 << iota |
| argInt |
| argRune |
| argString |
| argFloat |
| argComplex |
| argPointer |
| argError |
| anyType printfArgType = ^0 |
| ) |
| |
| type printVerb struct { |
| verb rune // User may provide verb through Formatter; could be a rune. |
| flags string // known flags are all ASCII |
| typ printfArgType |
| } |
| |
| // Common flag sets for printf verbs. |
| const ( |
| noFlag = "" |
| numFlag = " -+.0" |
| sharpNumFlag = " -+.0#" |
| allFlags = " -+.0#" |
| ) |
| |
| // printVerbs identifies which flags are known to printf for each verb. |
| var printVerbs = []printVerb{ |
| // '-' is a width modifier, always valid. |
| // '.' is a precision for float, max width for strings. |
| // '+' is required sign for numbers, Go format for %v. |
| // '#' is alternate format for several verbs. |
| // ' ' is spacer for numbers |
| {'%', noFlag, 0}, |
| {'b', sharpNumFlag, argInt | argFloat | argComplex | argPointer}, |
| {'c', "-", argRune | argInt}, |
| {'d', numFlag, argInt | argPointer}, |
| {'e', sharpNumFlag, argFloat | argComplex}, |
| {'E', sharpNumFlag, argFloat | argComplex}, |
| {'f', sharpNumFlag, argFloat | argComplex}, |
| {'F', sharpNumFlag, argFloat | argComplex}, |
| {'g', sharpNumFlag, argFloat | argComplex}, |
| {'G', sharpNumFlag, argFloat | argComplex}, |
| {'o', sharpNumFlag, argInt | argPointer}, |
| {'O', sharpNumFlag, argInt | argPointer}, |
| {'p', "-#", argPointer}, |
| {'q', " -+.0#", argRune | argInt | argString}, |
| {'s', " -+.0", argString}, |
| {'t', "-", argBool}, |
| {'T', "-", anyType}, |
| {'U', "-#", argRune | argInt}, |
| {'v', allFlags, anyType}, |
| {'w', allFlags, argError}, |
| {'x', sharpNumFlag, argRune | argInt | argString | argPointer | argFloat | argComplex}, |
| {'X', sharpNumFlag, argRune | argInt | argString | argPointer | argFloat | argComplex}, |
| } |
| |
| // okPrintfArg compares the formatState to the arguments actually present, |
| // reporting any discrepancies it can discern. If the final argument is ellipsissed, |
| // there's little it can do for that. |
| func okPrintfArg(pass *analysis.Pass, call *ast.CallExpr, state *formatState) (ok bool) { |
| var v printVerb |
| found := false |
| // Linear scan is fast enough for a small list. |
| for _, v = range printVerbs { |
| if v.verb == state.verb { |
| found = true |
| break |
| } |
| } |
| |
| // Could current arg implement fmt.Formatter? |
| // Skip check for the %w verb, which requires an error. |
| formatter := false |
| if v.typ != argError && state.argNum < len(call.Args) { |
| if tv, ok := pass.TypesInfo.Types[call.Args[state.argNum]]; ok { |
| formatter = isFormatter(tv.Type) |
| } |
| } |
| |
| if !formatter { |
| if !found { |
| pass.ReportRangef(call, "%s format %s has unknown verb %c", state.name, state.format, state.verb) |
| return false |
| } |
| for _, flag := range state.flags { |
| // TODO: Disable complaint about '0' for Go 1.10. To be fixed properly in 1.11. |
| // See issues 23598 and 23605. |
| if flag == '0' { |
| continue |
| } |
| if !strings.ContainsRune(v.flags, rune(flag)) { |
| pass.ReportRangef(call, "%s format %s has unrecognized flag %c", state.name, state.format, flag) |
| return false |
| } |
| } |
| } |
| // Verb is good. If len(state.argNums)>trueArgs, we have something like %.*s and all |
| // but the final arg must be an integer. |
| trueArgs := 1 |
| if state.verb == '%' { |
| trueArgs = 0 |
| } |
| nargs := len(state.argNums) |
| for i := 0; i < nargs-trueArgs; i++ { |
| argNum := state.argNums[i] |
| if !argCanBeChecked(pass, call, i, state) { |
| return |
| } |
| arg := call.Args[argNum] |
| if reason, ok := matchArgType(pass, argInt, arg); !ok { |
| details := "" |
| if reason != "" { |
| details = " (" + reason + ")" |
| } |
| pass.ReportRangef(call, "%s format %s uses non-int %s%s as argument of *", state.name, state.format, analysisutil.Format(pass.Fset, arg), details) |
| return false |
| } |
| } |
| |
| if state.verb == '%' || formatter { |
| return true |
| } |
| argNum := state.argNums[len(state.argNums)-1] |
| if !argCanBeChecked(pass, call, len(state.argNums)-1, state) { |
| return false |
| } |
| arg := call.Args[argNum] |
| if isFunctionValue(pass, arg) && state.verb != 'p' && state.verb != 'T' { |
| pass.ReportRangef(call, "%s format %s arg %s is a func value, not called", state.name, state.format, analysisutil.Format(pass.Fset, arg)) |
| return false |
| } |
| if reason, ok := matchArgType(pass, v.typ, arg); !ok { |
| typeString := "" |
| if typ := pass.TypesInfo.Types[arg].Type; typ != nil { |
| typeString = typ.String() |
| } |
| details := "" |
| if reason != "" { |
| details = " (" + reason + ")" |
| } |
| pass.ReportRangef(call, "%s format %s has arg %s of wrong type %s%s", state.name, state.format, analysisutil.Format(pass.Fset, arg), typeString, details) |
| return false |
| } |
| if v.typ&argString != 0 && v.verb != 'T' && !bytes.Contains(state.flags, []byte{'#'}) { |
| if methodName, ok := recursiveStringer(pass, arg); ok { |
| pass.ReportRangef(call, "%s format %s with arg %s causes recursive %s method call", state.name, state.format, analysisutil.Format(pass.Fset, arg), methodName) |
| return false |
| } |
| } |
| return true |
| } |
| |
| // recursiveStringer reports whether the argument e is a potential |
| // recursive call to stringer or is an error, such as t and &t in these examples: |
| // |
| // func (t *T) String() string { printf("%s", t) } |
| // func (t T) Error() string { printf("%s", t) } |
| // func (t T) String() string { printf("%s", &t) } |
| func recursiveStringer(pass *analysis.Pass, e ast.Expr) (string, bool) { |
| typ := pass.TypesInfo.Types[e].Type |
| |
| // It's unlikely to be a recursive stringer if it has a Format method. |
| if isFormatter(typ) { |
| return "", false |
| } |
| |
| // Does e allow e.String() or e.Error()? |
| strObj, _, _ := types.LookupFieldOrMethod(typ, false, pass.Pkg, "String") |
| strMethod, strOk := strObj.(*types.Func) |
| errObj, _, _ := types.LookupFieldOrMethod(typ, false, pass.Pkg, "Error") |
| errMethod, errOk := errObj.(*types.Func) |
| if !strOk && !errOk { |
| return "", false |
| } |
| |
| // inScope returns true if e is in the scope of f. |
| inScope := func(e ast.Expr, f *types.Func) bool { |
| return f.Scope() != nil && f.Scope().Contains(e.Pos()) |
| } |
| |
| // Is the expression e within the body of that String or Error method? |
| var method *types.Func |
| if strOk && strMethod.Pkg() == pass.Pkg && inScope(e, strMethod) { |
| method = strMethod |
| } else if errOk && errMethod.Pkg() == pass.Pkg && inScope(e, errMethod) { |
| method = errMethod |
| } else { |
| return "", false |
| } |
| |
| sig := method.Type().(*types.Signature) |
| if !isStringer(sig) { |
| return "", false |
| } |
| |
| // Is it the receiver r, or &r? |
| if u, ok := e.(*ast.UnaryExpr); ok && u.Op == token.AND { |
| e = u.X // strip off & from &r |
| } |
| if id, ok := e.(*ast.Ident); ok { |
| if pass.TypesInfo.Uses[id] == sig.Recv() { |
| return method.FullName(), true |
| } |
| } |
| return "", false |
| } |
| |
| // isStringer reports whether the method signature matches the String() definition in fmt.Stringer. |
| func isStringer(sig *types.Signature) bool { |
| return sig.Params().Len() == 0 && |
| sig.Results().Len() == 1 && |
| sig.Results().At(0).Type() == types.Typ[types.String] |
| } |
| |
| // isFunctionValue reports whether the expression is a function as opposed to a function call. |
| // It is almost always a mistake to print a function value. |
| func isFunctionValue(pass *analysis.Pass, e ast.Expr) bool { |
| if typ := pass.TypesInfo.Types[e].Type; typ != nil { |
| _, ok := typ.(*types.Signature) |
| return ok |
| } |
| return false |
| } |
| |
| // argCanBeChecked reports whether the specified argument is statically present; |
| // it may be beyond the list of arguments or in a terminal slice... argument, which |
| // means we can't see it. |
| func argCanBeChecked(pass *analysis.Pass, call *ast.CallExpr, formatArg int, state *formatState) bool { |
| argNum := state.argNums[formatArg] |
| if argNum <= 0 { |
| // Shouldn't happen, so catch it with prejudice. |
| panic("negative arg num") |
| } |
| if argNum < len(call.Args)-1 { |
| return true // Always OK. |
| } |
| if call.Ellipsis.IsValid() { |
| return false // We just can't tell; there could be many more arguments. |
| } |
| if argNum < len(call.Args) { |
| return true |
| } |
| // There are bad indexes in the format or there are fewer arguments than the format needs. |
| // This is the argument number relative to the format: Printf("%s", "hi") will give 1 for the "hi". |
| arg := argNum - state.firstArg + 1 // People think of arguments as 1-indexed. |
| pass.ReportRangef(call, "%s format %s reads arg #%d, but call has %v", state.name, state.format, arg, count(len(call.Args)-state.firstArg, "arg")) |
| return false |
| } |
| |
| // printFormatRE is the regexp we match and report as a possible format string |
| // in the first argument to unformatted prints like fmt.Print. |
| // We exclude the space flag, so that printing a string like "x % y" is not reported as a format. |
| var printFormatRE = regexp.MustCompile(`%` + flagsRE + numOptRE + `\.?` + numOptRE + indexOptRE + verbRE) |
| |
| const ( |
| flagsRE = `[+\-#]*` |
| indexOptRE = `(\[[0-9]+\])?` |
| numOptRE = `([0-9]+|` + indexOptRE + `\*)?` |
| verbRE = `[bcdefgopqstvxEFGTUX]` |
| ) |
| |
| // checkPrint checks a call to an unformatted print routine such as Println. |
| func checkPrint(pass *analysis.Pass, call *ast.CallExpr, fn *types.Func) { |
| firstArg := 0 |
| typ := pass.TypesInfo.Types[call.Fun].Type |
| if typ == nil { |
| // Skip checking functions with unknown type. |
| return |
| } |
| if sig, ok := typ.(*types.Signature); ok { |
| if !sig.Variadic() { |
| // Skip checking non-variadic functions. |
| return |
| } |
| params := sig.Params() |
| firstArg = params.Len() - 1 |
| |
| typ := params.At(firstArg).Type() |
| typ = typ.(*types.Slice).Elem() |
| it, ok := typ.(*types.Interface) |
| if !ok || !it.Empty() { |
| // Skip variadic functions accepting non-interface{} args. |
| return |
| } |
| } |
| args := call.Args |
| if len(args) <= firstArg { |
| // Skip calls without variadic args. |
| return |
| } |
| args = args[firstArg:] |
| |
| if firstArg == 0 { |
| if sel, ok := call.Args[0].(*ast.SelectorExpr); ok { |
| if x, ok := sel.X.(*ast.Ident); ok { |
| if x.Name == "os" && strings.HasPrefix(sel.Sel.Name, "Std") { |
| pass.ReportRangef(call, "%s does not take io.Writer but has first arg %s", fn.FullName(), analysisutil.Format(pass.Fset, call.Args[0])) |
| } |
| } |
| } |
| } |
| |
| arg := args[0] |
| if s, ok := stringConstantExpr(pass, arg); ok { |
| // Ignore trailing % character |
| // The % in "abc 0.0%" couldn't be a formatting directive. |
| s = strings.TrimSuffix(s, "%") |
| if strings.Contains(s, "%") { |
| m := printFormatRE.FindStringSubmatch(s) |
| if m != nil { |
| pass.ReportRangef(call, "%s call has possible Printf formatting directive %s", fn.FullName(), m[0]) |
| } |
| } |
| } |
| if strings.HasSuffix(fn.Name(), "ln") { |
| // The last item, if a string, should not have a newline. |
| arg = args[len(args)-1] |
| if s, ok := stringConstantExpr(pass, arg); ok { |
| if strings.HasSuffix(s, "\n") { |
| pass.ReportRangef(call, "%s arg list ends with redundant newline", fn.FullName()) |
| } |
| } |
| } |
| for _, arg := range args { |
| if isFunctionValue(pass, arg) { |
| pass.ReportRangef(call, "%s arg %s is a func value, not called", fn.FullName(), analysisutil.Format(pass.Fset, arg)) |
| } |
| if methodName, ok := recursiveStringer(pass, arg); ok { |
| pass.ReportRangef(call, "%s arg %s causes recursive call to %s method", fn.FullName(), analysisutil.Format(pass.Fset, arg), methodName) |
| } |
| } |
| } |
| |
| // count(n, what) returns "1 what" or "N whats" |
| // (assuming the plural of what is whats). |
| func count(n int, what string) string { |
| if n == 1 { |
| return "1 " + what |
| } |
| return fmt.Sprintf("%d %ss", n, what) |
| } |
| |
| // stringSet is a set-of-nonempty-strings-valued flag. |
| // Note: elements without a '.' get lower-cased. |
| type stringSet map[string]bool |
| |
| func (ss stringSet) String() string { |
| var list []string |
| for name := range ss { |
| list = append(list, name) |
| } |
| sort.Strings(list) |
| return strings.Join(list, ",") |
| } |
| |
| func (ss stringSet) Set(flag string) error { |
| for _, name := range strings.Split(flag, ",") { |
| if len(name) == 0 { |
| return fmt.Errorf("empty string") |
| } |
| if !strings.Contains(name, ".") { |
| name = strings.ToLower(name) |
| } |
| ss[name] = true |
| } |
| return nil |
| } |