parent
baae7a46fd
commit
7ede37cc0b
@ -0,0 +1,177 @@
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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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)
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// addRuntimeAPI exposes additional functions in the runtime
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// package that may be helpful when hiding information
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// during execution is required.
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func addRuntimeAPI(filename string, file *ast.File) {
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switchPanicPrints := func(node ast.Node) bool {
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call, ok := node.(*ast.CallExpr)
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if !ok {
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return true
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}
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id, ok := call.Fun.(*ast.Ident)
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if !ok {
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return true
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}
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if id.Name == "print" {
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id.Name = "panicprint"
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return false
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}
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return true
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}
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switch filename {
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case "debug.go":
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// Add hideFatalErrors function and internal fatalErrorsHidden variable
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file.Decls = append(file.Decls, hideFatalErrorsDecls...)
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case "error.go":
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// Add a function panicprint, that does nothing if panics are
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// hidden, otherwise forwards arguments to printany to print them
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// as normal. Although we add an if statement to printany to do
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// nothing if panics are hidden, printany only takes one argument,
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// and both print and printany are used to print panic messages.
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// panicprint's entire purpose is to act as a replacement to print
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// that respects hideFatalErrors, and print is variadic, so print
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// must be replaced by a variadic function, hence panicprint.
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//
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// We will also add two statements to printany:
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// 1. An if statement that returns early if panics are hidden
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// 2. An additional case statement that handles printing runtime.hex
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// values. Without this case statement, the default case will print
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// the runtime.hex values in a way not consistent with normal panic
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// outputs
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for _, decl := range file.Decls {
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funcDecl, ok := decl.(*ast.FuncDecl)
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if ok && funcDecl.Name.Name == "printany" {
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for _, stmt := range funcDecl.Body.List {
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switchStmt, ok := stmt.(*ast.TypeSwitchStmt)
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if !ok {
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continue
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}
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switchStmt.Body.List = append(switchStmt.Body.List, printanyHexCase)
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break
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}
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funcDecl.Body.List = append([]ast.Stmt{fatalErrorsHiddenCheckStmt}, funcDecl.Body.List...)
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break
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}
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}
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file.Decls = append(file.Decls, panicprintDecl)
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default:
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// Change all calls to print, which we don't control, to
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// panicprint, which we do control and does the same thing.
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ast.Inspect(file, switchPanicPrints)
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}
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}
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var fatalErrorsHiddenCheckStmt = &ast.IfStmt{
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Cond: &ast.Ident{Name: "fatalErrorsHidden"},
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Body: &ast.BlockStmt{List: []ast.Stmt{
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&ast.ReturnStmt{},
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}},
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}
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var hideFatalErrorsDecls = []ast.Decl{
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&ast.GenDecl{
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Tok: token.VAR,
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Specs: []ast.Spec{
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&ast.ValueSpec{
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Names: []*ast.Ident{
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{Name: "fatalErrorsHidden"},
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},
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Type: &ast.Ident{Name: "bool"},
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},
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},
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},
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&ast.FuncDecl{
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Name: &ast.Ident{Name: "hideFatalErrors"},
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Type: &ast.FuncType{
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Params: &ast.FieldList{
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List: []*ast.Field{
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{
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Names: []*ast.Ident{
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{Name: "hide"},
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},
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Type: &ast.Ident{Name: "bool"},
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},
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},
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},
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},
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Body: &ast.BlockStmt{
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List: []ast.Stmt{
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&ast.AssignStmt{
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Lhs: []ast.Expr{
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&ast.Ident{Name: "fatalErrorsHidden"},
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},
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Tok: token.ASSIGN,
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Rhs: []ast.Expr{
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&ast.Ident{Name: "hide"},
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},
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},
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},
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},
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},
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}
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var printanyHexCase = &ast.CaseClause{
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List: []ast.Expr{
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&ast.Ident{Name: "hex"},
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},
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Body: []ast.Stmt{
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&ast.ExprStmt{
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X: &ast.CallExpr{
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Fun: &ast.Ident{Name: "print"},
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Args: []ast.Expr{
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&ast.Ident{Name: "v"},
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},
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},
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},
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},
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}
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var panicprintDecl = &ast.FuncDecl{
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Name: &ast.Ident{Name: "panicprint"},
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Type: &ast.FuncType{Params: &ast.FieldList{
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List: []*ast.Field{
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{
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Names: []*ast.Ident{
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{Name: "args"},
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},
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Type: &ast.Ellipsis{Elt: &ast.InterfaceType{
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Methods: &ast.FieldList{},
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}},
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},
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},
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}},
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Body: &ast.BlockStmt{List: []ast.Stmt{
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&ast.IfStmt{
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Cond: &ast.Ident{Name: "fatalErrorsHidden"},
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Body: &ast.BlockStmt{List: []ast.Stmt{
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&ast.ReturnStmt{},
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}},
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},
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&ast.RangeStmt{
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Key: &ast.Ident{Name: "_"},
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Value: &ast.Ident{Name: "arg"},
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Tok: token.DEFINE,
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X: &ast.Ident{Name: "args"},
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Body: &ast.BlockStmt{List: []ast.Stmt{
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&ast.ExprStmt{X: &ast.CallExpr{
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Fun: &ast.Ident{Name: "printany"},
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Args: []ast.Expr{
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&ast.Ident{Name: "arg"},
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},
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}},
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}},
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},
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}},
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}
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@ -0,0 +1,21 @@
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garble build
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! exec ./main
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cmp stderr main.stderr
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-- go.mod --
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module test/main
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-- main.go --
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package main
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import _ "unsafe"
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//go:linkname hideFatalErrors runtime.hideFatalErrors
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func hideFatalErrors(hide bool)
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func init() { hideFatalErrors(true) }
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func main() {
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panic("ya like jazz?")
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}
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-- main.stderr --
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