mirror of
https://github.com/golang/go
synced 2024-11-05 17:46:16 -07:00
850ba653f7
This reverts commit 5b72e8e9bb.
Change-Id: I75270045022d69444b7812f290cdd5861af13feb
Reviewed-on: https://go-review.googlesource.com/8915
Reviewed-by: Robert Griesemer <gri@golang.org>
99 lines
2.7 KiB
Go
99 lines
2.7 KiB
Go
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Check for invalid uintptr -> unsafe.Pointer conversions.
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package main
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import (
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"go/ast"
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"go/token"
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"golang.org/x/tools/go/types"
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)
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func init() {
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register("unsafeptr",
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"check for misuse of unsafe.Pointer",
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checkUnsafePointer,
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callExpr)
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}
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func checkUnsafePointer(f *File, node ast.Node) {
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x := node.(*ast.CallExpr)
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if len(x.Args) != 1 {
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return
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}
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if f.hasBasicType(x.Fun, types.UnsafePointer) && f.hasBasicType(x.Args[0], types.Uintptr) && !f.isSafeUintptr(x.Args[0]) {
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f.Badf(x.Pos(), "possible misuse of unsafe.Pointer")
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}
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}
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// isSafeUintptr reports whether x - already known to be a uintptr -
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// is safe to convert to unsafe.Pointer. It is safe if x is itself derived
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// directly from an unsafe.Pointer via conversion and pointer arithmetic
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// or if x is the result of reflect.Value.Pointer or reflect.Value.UnsafeAddr
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// or obtained from the Data field of a *reflect.SliceHeader or *reflect.StringHeader.
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func (f *File) isSafeUintptr(x ast.Expr) bool {
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switch x := x.(type) {
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case *ast.ParenExpr:
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return f.isSafeUintptr(x.X)
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case *ast.SelectorExpr:
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switch x.Sel.Name {
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case "Data":
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// reflect.SliceHeader and reflect.StringHeader are okay,
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// but only if they are pointing at a real slice or string.
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// It's not okay to do:
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// var x SliceHeader
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// x.Data = uintptr(unsafe.Pointer(...))
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// ... use x ...
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// p := unsafe.Pointer(x.Data)
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// because in the middle the garbage collector doesn't
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// see x.Data as a pointer and so x.Data may be dangling
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// by the time we get to the conversion at the end.
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// For now approximate by saying that *Header is okay
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// but Header is not.
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pt, ok := f.pkg.types[x.X].Type.(*types.Pointer)
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if ok {
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t, ok := pt.Elem().(*types.Named)
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if ok && t.Obj().Pkg().Path() == "reflect" {
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switch t.Obj().Name() {
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case "StringHeader", "SliceHeader":
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return true
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}
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}
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}
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}
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case *ast.CallExpr:
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switch len(x.Args) {
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case 0:
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// maybe call to reflect.Value.Pointer or reflect.Value.UnsafeAddr.
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sel, ok := x.Fun.(*ast.SelectorExpr)
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if !ok {
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break
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}
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switch sel.Sel.Name {
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case "Pointer", "UnsafeAddr":
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t, ok := f.pkg.types[sel.X].Type.(*types.Named)
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if ok && t.Obj().Pkg().Path() == "reflect" && t.Obj().Name() == "Value" {
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return true
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}
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}
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case 1:
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// maybe conversion of uintptr to unsafe.Pointer
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return f.hasBasicType(x.Fun, types.Uintptr) && f.hasBasicType(x.Args[0], types.UnsafePointer)
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}
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case *ast.BinaryExpr:
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switch x.Op {
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case token.ADD, token.SUB:
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return f.isSafeUintptr(x.X) && !f.isSafeUintptr(x.Y)
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}
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}
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return false
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}
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