| 1 | // Copyright 2018 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 | // The unmarshal package defines an Analyzer that checks for passing |
| 6 | // non-pointer or non-interface types to unmarshal and decode functions. |
| 7 | package unmarshal |
| 8 | |
| 9 | import ( |
| 10 | "go/ast" |
| 11 | "go/types" |
| 12 | |
| 13 | "golang.org/x/tools/go/analysis" |
| 14 | "golang.org/x/tools/go/analysis/passes/inspect" |
| 15 | "golang.org/x/tools/go/ast/inspector" |
| 16 | "golang.org/x/tools/go/types/typeutil" |
| 17 | "golang.org/x/tools/internal/typeparams" |
| 18 | ) |
| 19 | |
| 20 | const Doc = `report passing non-pointer or non-interface values to unmarshal |
| 21 | |
| 22 | The unmarshal analysis reports calls to functions such as json.Unmarshal |
| 23 | in which the argument type is not a pointer or an interface.` |
| 24 | |
| 25 | var Analyzer = &analysis.Analyzer{ |
| 26 | Name: "unmarshal", |
| 27 | Doc: Doc, |
| 28 | Requires: []*analysis.Analyzer{inspect.Analyzer}, |
| 29 | Run: run, |
| 30 | } |
| 31 | |
| 32 | func run(pass *analysis.Pass) (interface{}, error) { |
| 33 | switch pass.Pkg.Path() { |
| 34 | case "encoding/gob", "encoding/json", "encoding/xml", "encoding/asn1": |
| 35 | // These packages know how to use their own APIs. |
| 36 | // Sometimes they are testing what happens to incorrect programs. |
| 37 | return nil, nil |
| 38 | } |
| 39 | |
| 40 | inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector) |
| 41 | |
| 42 | nodeFilter := []ast.Node{ |
| 43 | (*ast.CallExpr)(nil), |
| 44 | } |
| 45 | inspect.Preorder(nodeFilter, func(n ast.Node) { |
| 46 | call := n.(*ast.CallExpr) |
| 47 | fn := typeutil.StaticCallee(pass.TypesInfo, call) |
| 48 | if fn == nil { |
| 49 | return // not a static call |
| 50 | } |
| 51 | |
| 52 | // Classify the callee (without allocating memory). |
| 53 | argidx := -1 |
| 54 | recv := fn.Type().(*types.Signature).Recv() |
| 55 | if fn.Name() == "Unmarshal" && recv == nil { |
| 56 | // "encoding/json".Unmarshal |
| 57 | // "encoding/xml".Unmarshal |
| 58 | // "encoding/asn1".Unmarshal |
| 59 | switch fn.Pkg().Path() { |
| 60 | case "encoding/json", "encoding/xml", "encoding/asn1": |
| 61 | argidx = 1 // func([]byte, interface{}) |
| 62 | } |
| 63 | } else if fn.Name() == "Decode" && recv != nil { |
| 64 | // (*"encoding/json".Decoder).Decode |
| 65 | // (* "encoding/gob".Decoder).Decode |
| 66 | // (* "encoding/xml".Decoder).Decode |
| 67 | t := recv.Type() |
| 68 | if ptr, ok := t.(*types.Pointer); ok { |
| 69 | t = ptr.Elem() |
| 70 | } |
| 71 | tname := t.(*types.Named).Obj() |
| 72 | if tname.Name() == "Decoder" { |
| 73 | switch tname.Pkg().Path() { |
| 74 | case "encoding/json", "encoding/xml", "encoding/gob": |
| 75 | argidx = 0 // func(interface{}) |
| 76 | } |
| 77 | } |
| 78 | } |
| 79 | if argidx < 0 { |
| 80 | return // not a function we are interested in |
| 81 | } |
| 82 | |
| 83 | if len(call.Args) < argidx+1 { |
| 84 | return // not enough arguments, e.g. called with return values of another function |
| 85 | } |
| 86 | |
| 87 | t := pass.TypesInfo.Types[call.Args[argidx]].Type |
| 88 | switch t.Underlying().(type) { |
| 89 | case *types.Pointer, *types.Interface, *typeparams.TypeParam: |
| 90 | return |
| 91 | } |
| 92 | |
| 93 | switch argidx { |
| 94 | case 0: |
| 95 | pass.Reportf(call.Lparen, "call of %s passes non-pointer", fn.Name()) |
| 96 | case 1: |
| 97 | pass.Reportf(call.Lparen, "call of %s passes non-pointer as second argument", fn.Name()) |
| 98 | } |
| 99 | }) |
| 100 | return nil, nil |
| 101 | } |
| 102 |
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