goloader

README

Goloader

Goloader can load and run Golang code at runtime.

Forked from https://github.com/dearplain/goloader, Take over maintenance because the original author is not in maintenance

How does it work?

Goloader works like a linker: it relocates the address of symbols in an object file, generates runnable code, and then reuses the runtime function and the type pointer of the loader.

Goloader provides some information to the runtime and gc of Go, which allows it to work correctly with them.

Please note that Goloader is not a scripting engine. It reads the output of Go compiler and makes them runnable. All features of Go are supported, and run just as fast and lightweight as native Go code.

Comparison with plugin

Goloader reuses the Go runtime, which makes it much smaller. And code loaded by Goloader is unloadable.

Goloader supports pprof tool(Yes, you can see code loaded by Goloader in pprof).

Goloader don't support obj file with cgo.

Build

Make sure you're using go >= 1.8.

First, execute the following command, then do build and test. This is because Goloader relies on the internal package, which is forbidden by the Go compiler.

cp -r $GOROOT/src/cmd/internal $GOROOT/src/cmd/objfile

Examples

If use go module or go version >= 1.20

export GO111MODULE=on
go list -export -f '{{if .Export}}packagefile {{.ImportPath}}={{.Export}}{{end}}' std `go list -f {{.Imports}} $GOPATH/src/github.com/pkujhd/goloader/examples/schedule/schedule.go | awk '{sub(/^\[/, ""); print }' | awk '{sub(/\]$/, ""); print }'` > importcfg
go tool compile -importcfg importcfg $GOPATH/src/github.com/pkujhd/goloader/examples/schedule/schedule.go

If use go path and go version < 1.20

export GO111MODULE=auto
go build github.com/pkujhd/goloader/examples/loader

go tool compile $GOPATH/src/github.com/pkujhd/goloader/examples/schedule/schedule.go
./loader -o schedule.o -run main.main -times 10

go tool compile $GOPATH/src/github.com/pkujhd/goloader/examples/base/base.go
./loader -o base.o -run main.main

go tool compile $GOPATH/src/github.com/pkujhd/goloader/examples/http/http.go
./loader -o http.o -run main.main

go install github.com/pkujhd/goloader/examples/basecontext
go tool compile -I $GOPATH/pkg/`go env GOOS`_`go env GOARCH`/ $GOPATH/src/github.com/pkujhd/goloader/examples/inter/inter.go
./loader -o $GOPATH/pkg/`go env GOOS`_`go env GOARCH`/github.com/pkujhd/goloader/examples/basecontext.a:github.com/pkujhd/goloader/examples/basecontext -o inter.o

#build multiple go files
go tool compile -I $GOPATH/pkg/`go env GOOS`_`go env GOARCH`/ -o test.o test1.go test2.go
./loader -o test.o -run main.main

Warning

Don't use "-s -w" compile argument, It strips symbol table.

This has currently only been tested and developed on:

Golang 1.8-1.21 (x64/x86, darwin, linux, windows)

Golang 1.10-1.21 (arm, linux, android)

Golang 1.8-1.21 (arm64, linux, android)

Golang 1.16-1.21 (arm64, darwin)

Documentation

Index

• Constants
• func MakeThreadJITCodeExecutable(ptr uintptr, len int)
• func Mmap(size int) ([]byte, error)
• func MmapData(size int) ([]byte, error)
• func Munmap(b []byte) (err error)
• func Parse(f *os.File, pkgpath *string) ([]string, error)
• func RegSymbol(symPtr map[string]uintptr) error
• func RegSymbolWithSo(symPtr map[string]uintptr, path string) error
• func RegTypes(symPtr map[string]uintptr, interfaces ...interface{})
• type CodeModule
  • func Load(linker *Linker, symPtr map[string]uintptr) (codeModule *CodeModule, err error)
  • func (cm *CodeModule) Unload()
• type Linker
  • func ReadObj(f *os.File, pkgpath *string) (*Linker, error)
  • func ReadObjs(files []string, pkgPath []string) (*Linker, error)

Constants

const (
	PtrSize    = 4 << (^uintptr(0) >> 63)
	Uint32Size = int(unsafe.Sizeof(uint32(0)))
	IntSize    = int(unsafe.Sizeof(int(0)))
	UInt64Size = int(unsafe.Sizeof(uint64(0)))

	FindFuncBucketSize = int(unsafe.Sizeof(findfuncbucket{}))
	PCHeaderSize       = int(unsafe.Sizeof(pcHeader{}))
	InvalidHandleValue = ^uintptr(0)
	InvalidOffset      = int(-1)
	PageSize           = 1 << 12 //4096
)

size

const (
	EmptyString    = ""
	DefaultPkgPath = "main"
	ZeroByte       = byte(0x00)
)

const (
	FileSymPrefix  = "gofile.."
	MainPkgPrefix  = "main."
	OsStdout       = "os.Stdout"
	GOTPCRELSuffix = "·f"
)

string match prefix/suffix

const (
	KindGCProg = 1 << 6
)

const (
	RuntimeDeferReturn = "runtime.deferreturn"
)

runtime symbol

const (
	TLSNAME = "(TLS)"
)

Functions

func MakeThreadJITCodeExecutable

func MakeThreadJITCodeExecutable(ptr uintptr, len int)

func Mmap

func Mmap(size int) ([]byte, error)

func MmapData

func MmapData(size int) ([]byte, error)

func Munmap

func Munmap(b []byte) (err error)

func Parse

func Parse(f *os.File, pkgpath *string) ([]string, error)

func RegSymbol

func RegSymbol(symPtr map[string]uintptr) error

func RegSymbolWithSo

func RegSymbolWithSo(symPtr map[string]uintptr, path string) error

func RegTypes

func RegTypes(symPtr map[string]uintptr, interfaces ...interface{})

Types

type CodeModule

type CodeModule struct {
	Syms map[string]uintptr
	// contains filtered or unexported fields
}

func Load

func Load(linker *Linker, symPtr map[string]uintptr) (codeModule *CodeModule, err error)

func (*CodeModule) Unload

func (cm *CodeModule) Unload()

type Linker

type Linker struct {
	// contains filtered or unexported fields
}

func ReadObj

func ReadObj(f *os.File, pkgpath *string) (*Linker, error)

func ReadObjs

func ReadObjs(files []string, pkgPath []string) (*Linker, error)