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138 lines
3.7 KiB
Go
138 lines
3.7 KiB
Go
// Copyright (c) 2020, The Garble Authors.
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// See LICENSE for licensing information.
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package main
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import (
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"fmt"
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"go/ast"
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mathrand "math/rand"
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"strings"
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"golang.org/x/tools/go/ast/astutil"
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)
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// PosMin is the smallest correct value for the line number.
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// Source: https://go.googlesource.com/go/+/refs/heads/master/src/cmd/compile/internal/syntax/parser_test.go#229
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const PosMin = 1
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// detachedDirectives is a list of Go compiler directives which don't need to go
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// right next to a Go declaration. Unlike all other detached comments, these
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// need to be kept around as they alter compiler behavior.
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var detachedDirectives = []string{
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"// +build",
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"//go:linkname",
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"//go:cgo_ldflag",
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"//go:cgo_dynamic_linker",
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"//go:cgo_export_static",
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"//go:cgo_export_dynamic",
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"//go:cgo_import_static",
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"//go:cgo_import_dynamic",
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}
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func isDirective(text string, directives []string) bool {
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for _, prefix := range directives {
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if strings.HasPrefix(text, prefix) {
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return true
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}
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}
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return false
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}
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func prependComment(group *ast.CommentGroup, comment *ast.Comment) *ast.CommentGroup {
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if group == nil {
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return &ast.CommentGroup{List: []*ast.Comment{comment}}
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}
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group.List = append([]*ast.Comment{comment}, group.List...)
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return group
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}
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// Remove all comments from CommentGroup except //go: directives.
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// go:linkname directives are removed, since they're collected and rewritten
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// separately.
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func clearCommentGroup(group *ast.CommentGroup) *ast.CommentGroup {
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if group == nil {
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return nil
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}
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var comments []*ast.Comment
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for _, comment := range group.List {
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if strings.HasPrefix(comment.Text, "//go:") && !strings.HasPrefix(comment.Text, "//go:linkname") {
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comments = append(comments, &ast.Comment{Text: comment.Text})
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}
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}
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if len(comments) == 0 {
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return nil
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}
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return &ast.CommentGroup{List: comments}
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}
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// Remove all comments from Doc (if any) except //go: directives.
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func clearNodeComments(node ast.Node) {
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switch n := node.(type) {
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case *ast.Field:
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n.Doc = clearCommentGroup(n.Doc)
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n.Comment = nil
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case *ast.ImportSpec:
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n.Doc = clearCommentGroup(n.Doc)
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n.Comment = nil
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case *ast.ValueSpec:
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n.Doc = clearCommentGroup(n.Doc)
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n.Comment = nil
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case *ast.TypeSpec:
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n.Doc = clearCommentGroup(n.Doc)
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n.Comment = nil
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case *ast.GenDecl:
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n.Doc = clearCommentGroup(n.Doc)
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case *ast.FuncDecl:
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n.Doc = clearCommentGroup(n.Doc)
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case *ast.File:
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n.Doc = clearCommentGroup(n.Doc)
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}
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}
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// transformLineInfo removes the comment except go directives and build tags. Converts comments to the node view.
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// It returns comments not attached to declarations and names of declarations which cannot be renamed.
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func transformLineInfo(file *ast.File, cgoFile bool) (detachedComments []string, f *ast.File) {
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prefix := ""
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if cgoFile {
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prefix = "_cgo_"
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}
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// Save build tags and add file name leak protection
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for _, group := range file.Comments {
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for _, comment := range group.List {
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if isDirective(comment.Text, detachedDirectives) {
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detachedComments = append(detachedComments, comment.Text)
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}
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}
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}
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detachedComments = append(detachedComments, "", "//line "+prefix+":1")
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file.Comments = nil
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newLines := mathrand.Perm(len(file.Decls))
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funcCounter := 0
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pre := func(cursor *astutil.Cursor) bool {
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node := cursor.Node()
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clearNodeComments(node)
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// If tiny mode is active information about line numbers is erased in object files
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if opts.Tiny {
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return true
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}
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funcDecl, ok := node.(*ast.FuncDecl)
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if !ok {
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return true
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}
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comment := &ast.Comment{Text: fmt.Sprintf("//line %s%c.go:%d", prefix, nameCharset[mathrand.Intn(len(nameCharset))], PosMin+newLines[funcCounter])}
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funcDecl.Doc = prependComment(funcDecl.Doc, comment)
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funcCounter++
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return true
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}
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return detachedComments, astutil.Apply(file, pre, nil).(*ast.File)
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}
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