burrowers-garble/testdata/script/linkname.txtar

exec garble build
exec ./main
cmp stderr main.stderr

# TODO: why is 'obfuscatedMethod' present?
! binsubstr main$exe 'obfuscatedFunc' 'ObfuscatedFunc'
binsubstr main$exe 'UnobfuscatedMethod'

[short] stop # no need to verify this with -short

go build
exec ./main
cmp stderr main.stderr
-- go.mod --
module test/main

go 1.23

replace big.chungus/meme => ./big.chungus/meme
require big.chungus/meme v0.0.0
-- a.go --
package main

// Call a function which is linknamed to another symbol.
// What's special here is that we obfuscate this call before the function declaration.
// If we decide not to obfuscate the name in the function declaration,
// we shouldn't obfuscate the name here either.
func linknameCalledInPkg() {
	println(obfuscatedFunc())
}

-- main.go --
package main

import (
	_ "os/exec"
	"reflect"
	_ "strings"
	"unsafe"

	_ "big.chungus/meme"
	"test/main/imported"
)

// A linkname to an external obfuscated func.
//go:linkname obfuscatedFunc test/main/imported.ObfuscatedFuncImpl
func obfuscatedFunc() string

// A linkname to an external obfuscated method.
//go:linkname obfuscatedMethod test/main/imported.Receiver.obfuscatedMethod
func obfuscatedMethod(imported.Receiver) string

// A linkname to an external unobfuscated method.
//go:linkname unobfuscatedMethod test/main/imported.Receiver.UnobfuscatedMethod
func unobfuscatedMethod(imported.Receiver) string

// A linkname to an external obfuscated pointer method, with an extra parameter.
//go:linkname obfuscatedPointerMethod test/main/imported.(*Receiver).obfuscatedPointerMethod
func obfuscatedPointerMethod(*imported.Receiver, string) string

// Similar to the above, but for std, plus having to define a type.
// Some libraries do abuse reflect in this way, unfortunately.
type rtype struct{}
//go:linkname rtype_ptrTo reflect.(*rtype).ptrTo
func rtype_ptrTo(*rtype) *rtype
//go:linkname rtype_NumMethod reflect.(*rtype).NumMethod
func rtype_NumMethod(*rtype) int

// A linkname to an entirely made up name, implemented elsewhere.
//go:linkname renamedFunc madeup.newName
func renamedFunc() string

// A linkname to an external non-obfuscated func in another
// module whose package path has a dot in it.
//go:linkname tagline big.chungus/meme.chungify
func tagline() string

// A linkname to an external non-obfuscated func with receiver which is also non-obfuscated
//go:linkname changeThing test/main/imported.(*channel).changeThing
func changeThing(c unsafe.Pointer, to string)

func main() {
	println(obfuscatedFunc())

	r := imported.Receiver{Field: "field value"}
	println(obfuscatedMethod(r))
	println(unobfuscatedMethod(r))
	println(obfuscatedPointerMethod(&r, "another value"))

	typ := reflect.TypeOf(new(error)).Elem()
	type emptyInterface struct {
		_   *rtype
		ptr unsafe.Pointer
	}
	rtyp := (*rtype)(((*emptyInterface)(unsafe.Pointer(&typ))).ptr)
	println("rtype_ptrTo non-nil", rtype_ptrTo(rtyp) != nil)
	println("rtype_NumMethod", rtype_NumMethod(rtyp))

	println(renamedFunc())
	println(tagline())
	println(imported.ByteIndex("01234", '3'))
	linknameCalledInPkg()

	a := imported.Return("initial_text")

	val := reflect.ValueOf(a)
	changeThing(val.UnsafePointer(), "to this")
	println(a.DoThing())

}
-- imported/imported.go --
package imported

import (
	_ "strings"
	_ "unsafe"

	"reflect"
)

type Test interface {
	DoThing() string
}

func Return(c string) Test {
	return &channel{dummy: c}
}

type channel struct {
	dummy string
}

var _ = reflect.TypeOf(channel{})

func (c *channel) DoThing() string {
	return c.dummy
}

func (c *channel) changeThing(to string) {
	c.dummy = to
}

func ObfuscatedFuncImpl() string {
	return "obfuscated func"
}

type Receiver struct{
	Field string
}

func (r Receiver) obfuscatedMethod() string {
	return "obfuscated method: " + r.Field
}

func (r *Receiver) obfuscatedPointerMethod(extra string) string {
	return "obfuscated pointer method: " + r.Field + " plus " + extra
}

func (r Receiver) UnobfuscatedMethod() string {
	return "unobfuscated method: " + r.Field
}

//go:linkname renamedFunc madeup.newName
func renamedFunc() string {
	return "renamed func"
}

// A linkname to an external non-obfuscated func.
// Different from byteIndex, as we call this from an importer package.
//go:linkname ByteIndex strings.IndexByte
func ByteIndex(s string, c byte) int
-- big.chungus/meme/go.mod --
module test/main

go 1.23
-- big.chungus/meme/dante.go --
package meme

func chungify() string {
	return "featuring Dante from the Devil May Cry series"
}
-- main.stderr --
obfuscated func
obfuscated method: field value
unobfuscated method: field value
obfuscated pointer method: field value plus another value
rtype_ptrTo non-nil true
rtype_NumMethod 1
renamed func
featuring Dante from the Devil May Cry series
3
obfuscated func
to this