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

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

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

This has currently only been tested and developed on:

Golang 1.8-1.16 (x64/x86, darwin, linux, windows)

Golang 1.10-1.16 (arm, linux)

Golang 1.8-1.16 (arm64(LE) linux)

Documentation

Index

• Constants
• func Mmap(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 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 Func
• type FuncInfo
• type InlTreeNode
• type Linker
  • func ReadObj(f *os.File, pkgpath *string) (*Linker, error)
  • func ReadObjs(files []string, pkgPath []string) (*Linker, error)
• type ObjSymbol
• type Pkg
• type Reloc
• type Sym

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)))

	ItabSize           = int(unsafe.Sizeof(itab{}))
	FindFuncBucketSize = int(unsafe.Sizeof(findfuncbucket{}))
	InlinedCallSize    = int(unsafe.Sizeof(inlinedCall{}))
	InvalidHandleValue = ^uintptr(0)
	InvalidOffset      = int(-1)
	InvalidIndex       = uint32(0xFFFFFFFF)
	PageSize           = 1 << 12 //4096
)

size

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

const (
	FileSymPrefix        = "gofile.."
	TypeImportPathPrefix = "type..importpath."
	TypeDoubleDotPrefix  = "type.."
	TypePrefix           = "type."
	ItabPrefix           = "go.itab."
	StkobjSuffix         = ".stkobj"
	InlineTreeSuffix     = ".inlinetree"
	OsStdout             = "os.Stdout"
)

string match prefix/suffix

const (
	R_ADDR = 1
	// R_ADDRARM64 relocates an adrp, add pair to compute the address of the
	// referenced symbol.
	R_ADDRARM64 = 3
	// R_ADDROFF resolves to a 32-bit offset from the beginning of the section
	// holding the data being relocated to the referenced symbol.
	R_ADDROFF = 5
	// R_WEAKADDROFF resolves just like R_ADDROFF but is a weak relocation.
	// A weak relocation does not make the symbol it refers to reachable,
	// and is only honored by the linker if the symbol is in some other way
	// reachable.
	R_WEAKADDROFF = 6
	R_CALL        = 8
	R_CALLARM     = 9
	R_CALLARM64   = 10
	R_CALLIND     = 11
)

copy from $GOROOT/src/cmd/internal/objabi/reloctype.go

const (
	RuntimeDeferReturn = "runtime.deferreturn"
)

runtime symbol

const (
	TLSNAME = "(TLS)"
)

Functions

func Mmap

func Mmap(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 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 Func

type Func struct {
	PCData   []uint32
	FuncData []uintptr
}

type FuncInfo

type FuncInfo struct {
	Args     uint32
	Locals   uint32
	FuncID   uint8
	PCSP     []byte
	PCFile   []byte
	PCLine   []byte
	PCInline []byte
	PCData   [][]byte
	File     []string
	FuncData []string
	InlTree  []InlTreeNode
}

type InlTreeNode

type InlTreeNode struct {
	Parent   int64
	File     string
	Line     int64
	Func     string
	ParentPC int64
}

type Linker

type Linker struct {
	Arch string
	// 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)

type ObjSymbol

type ObjSymbol struct {
	Name  string
	Kind  int    // kind of symbol
	DupOK bool   // are duplicate definitions okay?
	Size  int64  // size of corresponding data
	Data  []byte // memory image of symbol
	Reloc []Reloc
	Func  *FuncInfo // additional data for functions
}

type Pkg

type Pkg struct {
	Syms    map[string]*ObjSymbol
	Arch    string
	PkgPath string
	// contains filtered or unexported fields
}

type Reloc

type Reloc struct {
	Offset int
	Sym    *Sym
	Size   int
	Type   int
	Add    int
}

copy from $GOROOT/src/cmd/internal/goobj/read.go type Reloc struct

type Sym

type Sym struct {
	Name   string
	Kind   int
	Offset int
	Func   *Func
	Reloc  []Reloc
}

copy from $GOROOT/src/cmd/internal/goobj/read.go type Sym struct