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115 lines
2.9 KiB
Go
115 lines
2.9 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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const (
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// PosMax is the largest line or column value that can be represented without loss.
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// Source: https://go.googlesource.com/go/+/refs/heads/master/src/cmd/compile/internal/syntax/pos.go#11
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PosMax = 1 << 30
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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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PosMin = 1
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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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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:") {
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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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case *ast.ImportSpec:
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n.Doc = clearCommentGroup(n.Doc)
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case *ast.ValueSpec:
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n.Doc = clearCommentGroup(n.Doc)
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case *ast.TypeSpec:
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n.Doc = clearCommentGroup(n.Doc)
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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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func findBuildTags(commentGroups []*ast.CommentGroup) (buildTags []string) {
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for _, group := range commentGroups {
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for _, comment := range group.List {
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if !strings.Contains(comment.Text, "+build") {
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continue
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}
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buildTags = append(buildTags, comment.Text)
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}
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}
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return buildTags
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}
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func transformLineInfo(file *ast.File) ([]string, *ast.File) {
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// Save build tags and add file name leak protection
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extraComments := append(findBuildTags(file.Comments), "", "//line :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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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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if envGarbleTiny {
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funcDecl.Doc = prependComment(funcDecl.Doc, &ast.Comment{Text: "//line :1"})
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return true
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}
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comment := &ast.Comment{Text: fmt.Sprintf("//line %c.go:%d", nameCharset[mathrand.Intn(len(nameCharset))], 1+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 extraComments, astutil.Apply(file, pre, nil).(*ast.File)
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}
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