module.go

package goloader

import (
	"unsafe"
)

//go:linkname firstmoduledata runtime.firstmoduledata
var firstmoduledata moduledata

// findfunctab is an array of these structures.
// Each bucket represents 4096 bytes of the text segment.
// Each subbucket represents 256 bytes of the text segment.
// To find a function given a pc, locate the bucket and subbucket for
// that pc. Add together the idx and subbucket value to obtain a
// function index. Then scan the functab array starting at that
// index to find the target function.
// This table uses 20 bytes for every 4096 bytes of code, or ~0.5% overhead.
type findfuncbucket struct {
	idx        uint32
	subbuckets [16]byte
}

// Mapping information for secondary text sections
type textsect struct {
	vaddr    uintptr // prelinked section vaddr
	length   uintptr // section length
	baseaddr uintptr // relocated section address
}

type nameOff int32
type typeOff int32
type textOff int32

// A ptabEntry is generated by the compiler for each exported function
// and global variable in the main package of a plugin. It is used to
// initialize the plugin module's symbol map.
type ptabEntry struct {
	name nameOff
	typ  typeOff
}

type modulehash struct {
	modulename   string
	linktimehash string
	runtimehash  *string
}

type bitvector struct {
	n        int32 // # of bits
	bytedata *uint8
}

type stackmap struct {
	n        int32   // number of bitmaps
	nbit     int32   // number of bits in each bitmap
	bytedata [1]byte // bitmaps, each starting on a byte boundary
}

type funcInfo struct {
	*_func
	datap *moduledata
}

const minfunc = 16                 // minimum function size
const pcbucketsize = 256 * minfunc // size of bucket in the pc->func lookup table
const nsub = len(findfuncbucket{}.subbuckets)

//go:linkname step runtime.step
func step(p []byte, pc *uintptr, val *int32, first bool) (newp []byte, ok bool)

//go:linkname findfunc runtime.findfunc
func findfunc(pc uintptr) funcInfo

//go:linkname funcdata runtime.funcdata
func funcdata(f funcInfo, i int32) unsafe.Pointer

//go:linkname funcname runtime.funcname
func funcname(f funcInfo) string

//go:linkname gostringnocopy runtime.gostringnocopy
func gostringnocopy(str *byte) string

//go:linkname moduledataverify1 runtime.moduledataverify1
func moduledataverify1(datap *moduledata)

//go:linkname modulesinit runtime.modulesinit
func modulesinit()

//go:linkname progToPointerMask runtime.progToPointerMask
func progToPointerMask(prog *byte, size uintptr) bitvector

func addModule(module *moduledata) {
	modules[module] = true
	for datap := &firstmoduledata; ; {
		if datap.next == nil {
			datap.next = module
			break
		}
		datap = datap.next
	}
}
func removeModule(module interface{}) {
	prevp := &firstmoduledata
	for datap := &firstmoduledata; datap != nil; {
		if datap == module {
			prevp.next = datap.next
			break
		}
		prevp = datap
		datap = datap.next
	}
	delete(modules, module)
}