visdebug/null.go at master · tfogal/visdebug · GitHub

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/* Distributed under the MIT license.  See the LICENSE file.
 * Copyright (c) 2014--2016 Thomas Fogal */
package main

import (
	"./debug"
	"github.com/tfogal/ptrace"
)

// Null is like MallocTrace, but does no prints.
type Null struct {
	BaseEvent
	maddr uintptr
	faddr uintptr
}

func (n *Null) malloc(inferior *ptrace.Tracee,
	bp debug.Breakpoint) error {
	var stk x86_64
	// figure out where the caller is and set a BP there.
	retaddr := stk.RetAddr(inferior)

	if err := n.AddBP(inferior, retaddr, n.mallocret); err != nil {
		return err
	}
	return nil
}

func (n *Null) mallocret(inferior *ptrace.Tracee,
	bp debug.Breakpoint) error {
	// re-insert our BP for malloc.
	if err := n.AddBP(inferior, n.maddr, n.malloc); err != nil {
		return err
	}
	return nil
}

func (n *Null) free(inferior *ptrace.Tracee,
	bp debug.Breakpoint) error {
	var stk x86_64
	// make sure this BP gets re-added when we come back.
	// I do not understand why this needs the 'Top' variant, but it does...
	raddr := uintptr(stk.RetAddrTop(inferior))
	if err := n.AddBP(inferior, raddr, n.freeret); err != nil {
		return err
	}

	return nil
}

func (n *Null) freeret(inferior *ptrace.Tracee,
	bp debug.Breakpoint) error {
	if err := n.AddBP(inferior, n.faddr, n.free); err != nil {
		return err
	}

	return nil
}

func (n *Null) Setup(inferior *ptrace.Tracee) error {
	if err := n.BaseEvent.Setup(inferior); err != nil {
		return err
	}

	n.faddr = symbol("free", globals.symbols).Address()
	n.maddr = symbol("malloc", globals.symbols).Address()
	assert(n.faddr != 0x0)
	assert(n.maddr != 0x0)

	if err := n.AddBP(inferior, n.maddr, n.malloc); err != nil {
		return err
	}
	if err := n.AddBP(inferior, n.faddr, n.free); err != nil {
		return err
	}
	return nil
}

func (n *Null) Close(*ptrace.Tracee) error {
	return nil
}