utility_unix.go

// +build !windows

package gohook

import (
	"syscall"
)

func getPageAddr(ptr uintptr) uintptr {
	return ptr & ^(uintptr(syscall.Getpagesize() - 1))
}

func setPageWritable(addr uintptr, length int, prot int) {
	pageSize := syscall.Getpagesize()
	for p := getPageAddr(addr); p < addr+uintptr(length); p += uintptr(pageSize) {
		page := makeSliceFromPointer(p, pageSize)
		err := syscall.Mprotect(page, prot)
		if err != nil {
			panic(err)
		}
	}
}

func CopyInstruction(location uintptr, data []byte) {
	f := makeSliceFromPointer(location, len(data))
	setPageWritable(location, len(data), syscall.PROT_READ|syscall.PROT_WRITE|syscall.PROT_EXEC)
	sz := copy(f, data[:])
	setPageWritable(location, len(data), syscall.PROT_READ|syscall.PROT_EXEC)
	if sz != len(data) {
		panic("copy instruction to target failed")
	}
}