objc.go

package macho

import (
	"bytes"
	"encoding/binary"
	"errors"
	"fmt"
	"io"
	"strings"
	"unsafe"

	"github.com/blacktop/go-macho/types"
	"github.com/blacktop/go-macho/types/objc"
)

var ErrObjcSectionNotFound = errors.New("missing required ObjC section")
var ErrObjcSectionNEmpty = errors.New("required ObjC section is empty")

// TODO refactor into a pkg

func (f *File) PutObjC(addr uint64, obj any) {
	f.mu.Lock()
	f.objc[addr] = obj
	f.mu.Unlock()
}

func (f *File) GetObjC(addr uint64) (any, bool) {
	f.mu.Lock()
	defer f.mu.Unlock()
	val, ok := f.objc[addr]
	return val, ok
}

func (f *File) rebasePtr(ptr uint64) uint64 {
	if f.Flags.DylibInCache() {
		return ptr
	} else {
		return ptr + f.GetBaseAddress()
	}
}

// HasObjC returns true if MachO contains a __objc_imageinfo section
func (f *File) HasObjC() bool {
	for _, s := range f.Segments() {
		if strings.HasPrefix(s.Name, "__DATA") {
			if sec := f.Section(s.Name, "__objc_imageinfo"); sec != nil {
				return true
			}
		}
	}
	if f.CPU == types.CPUI386 {
		if sec := f.Section("__OBJC", "__image_info"); sec != nil {
			return true
		}
	}
	return false
}

// HasPlusLoadMethod returns true if MachO contains a __objc_nlclslist or __objc_nlcatlist section
func (f *File) HasPlusLoadMethod() bool {
	// TODO add the old way of detecting from dyld3/MachOAnalyzer.cpp
	for _, s := range f.Segments() {
		if strings.HasPrefix(s.Name, "__DATA") {
			if sec := f.Section(s.Name, "__objc_nlclslist"); sec != nil {
				return true
			}
			if sec := f.Section(s.Name, "__objc_nlcatlist"); sec != nil {
				return true
			}
		}
	}
	return false
}

// HasObjCMessageReferences returns true if MachO contains a __objc_msgrefs section
func (f *File) HasObjCMessageReferences() bool {
	for _, s := range f.Segments() {
		if strings.HasPrefix(s.Name, "__DATA") {
			if sec := f.Section(s.Name, "__objc_msgrefs"); sec != nil {
				return true
			}
		}
	}
	return false
}

// GetObjCToc returns a table of contents of the ObjC objects in the MachO
func (f *File) GetObjCToc() objc.Toc {
	var oInfo objc.Toc
	for _, sec := range f.Sections {
		if strings.HasPrefix(sec.SectionHeader.Seg, "__DATA") {
			switch sec.Name {
			case "__objc_classlist":
				oInfo.ClassList = sec.Size / f.pointerSize()
			case "__objc_nlclslist":
				oInfo.NonLazyClassList = sec.Size / f.pointerSize()
			case "__objc_catlist":
				oInfo.CatList = sec.Size / f.pointerSize()
			case "__objc_nlcatlist":
				oInfo.NonLazyCatList = sec.Size / f.pointerSize()
			case "__objc_protolist":
				oInfo.ProtoList = sec.Size / f.pointerSize()
			case "__objc_classrefs":
				oInfo.ClassRefs = sec.Size / f.pointerSize()
			case "__objc_superrefs":
				oInfo.SuperRefs = sec.Size / f.pointerSize()
			case "__objc_selrefs":
				oInfo.SelRefs = sec.Size / f.pointerSize()
			}
		} else if (f.CPU == types.CPUI386) && strings.EqualFold(sec.Name, "__OBJC") {
			if strings.EqualFold(sec.Name, "__message_refs") {
				oInfo.SelRefs += sec.SectionHeader.Size / 4
			} else if strings.EqualFold(sec.Name, "__class") {
				oInfo.ClassList += sec.SectionHeader.Size / 48
			} else if strings.EqualFold(sec.Name, "__protocol") {
				oInfo.ProtoList += sec.SectionHeader.Size / 20
			}
		}
		// if sec := f.Section("__TEXT", "__objc_stubs"); sec != nil {
		// 	oInfo.Stubs = sec.Size / f.pointerSize()
		// }
	}
	return oInfo
}

// GetObjCImageInfo returns the parsed __objc_imageinfo data
func (f *File) GetObjCImageInfo() (*objc.ImageInfo, error) {
	var imgInfo objc.ImageInfo
	for _, s := range f.Segments() {
		if strings.HasPrefix(s.Name, "__DATA") {
			if sec := f.Section(s.Name, "__objc_imageinfo"); sec != nil {
				off, err := f.vma.GetOffset(sec.Addr)
				if err != nil {
					return nil, fmt.Errorf("failed to convert vmaddr: %v", err)
				}
				f.cr.Seek(int64(off), io.SeekStart)

				dat := make([]byte, sec.Size)
				if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
					return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
				}

				if err := binary.Read(bytes.NewReader(dat), f.ByteOrder, &imgInfo); err != nil {
					return nil, fmt.Errorf("failed to read %T: %v", imgInfo, err)
				}

				return &imgInfo, nil
			}
		}
	}
	return nil, fmt.Errorf("macho does not contain __objc_imageinfo section: %w", ErrObjcSectionNotFound)
}

// GetObjCClassInfo returns the ClassRO64 (class_ro_t) for a given virtual memory address
func (f *File) GetObjCClassInfo(vmaddr uint64) (*objc.ClassRO64, error) {
	var classData objc.ClassRO64

	if err := f.cr.SeekToAddr(vmaddr); err != nil {
		return nil, fmt.Errorf("failed to seek to vmaddr: %v", err)
	}

	if err := binary.Read(f.cr, f.ByteOrder, &classData); err != nil {
		return nil, fmt.Errorf("failed to read %T: %v", classData, err)
	}

	// slide pointers
	classData.NameVMAddr = f.vma.Convert(classData.NameVMAddr)
	classData.IvarsVMAddr = f.vma.Convert(classData.IvarsVMAddr)
	classData.IvarLayoutVMAddr = f.vma.Convert(classData.IvarLayoutVMAddr)
	classData.BaseMethodsVMAddr = f.vma.Convert(classData.BaseMethodsVMAddr)
	classData.BaseProtocolsVMAddr = f.vma.Convert(classData.BaseProtocolsVMAddr)
	classData.WeakIvarLayoutVMAddr = f.vma.Convert(classData.WeakIvarLayoutVMAddr)
	classData.BasePropertiesVMAddr = f.vma.Convert(classData.BasePropertiesVMAddr)

	return &classData, nil
}

// GetObjCClassNames returns a map of section data virtual memory address to their class names
func (f *File) GetObjCClassNames() (map[uint64]string, error) {
	class2vmaddr := make(map[uint64]string)

	if sec := f.Section("__TEXT", "__objc_classname"); sec != nil { // Names for locally implemented classes
		if err := f.cr.SeekToAddr(sec.Addr); err != nil {
			return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
		}

		dat := make([]byte, sec.Size)
		if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
			return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
		}

		r := bytes.NewBuffer(dat)

		for {
			s, err := r.ReadString('\x00')
			if err == io.EOF {
				break
			}
			if err != nil {
				return nil, fmt.Errorf("failed to read from class name string pool: %v", err)
			}

			if len(strings.Trim(s, "\x00")) > 0 && types.IsASCII(strings.Trim(s, "\x00")) {
				class2vmaddr[sec.Addr+(sec.Size-uint64(r.Len()+len(s)))] = strings.Trim(s, "\x00")
			}
		}
	}

	return class2vmaddr, nil
}

// GetObjCMethodNames returns a map of section data virtual memory addresses to their method names
func (f *File) GetObjCMethodNames() (map[uint64]string, error) {
	meth2vmaddr := make(map[uint64]string)

	if sec := f.Section("__TEXT", "__objc_methname"); sec != nil { // Method names for locally implemented methods
		if err := f.cr.SeekToAddr(sec.Addr); err != nil {
			return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
		}

		dat := make([]byte, sec.Size)
		if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
			return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
		}

		r := bytes.NewBuffer(dat)

		for {
			s, err := r.ReadString('\x00')
			if err == io.EOF {
				break
			}
			if err != nil {
				return nil, fmt.Errorf("failed to read from method name string pool: %v", err)
			}

			if len(strings.Trim(s, "\x00")) > 0 && types.IsASCII(strings.Trim(s, "\x00")) {
				meth2vmaddr[sec.Addr+(sec.Size-uint64(r.Len()+len(s)))] = strings.Trim(s, "\x00")
			}
		}
	}

	return meth2vmaddr, nil
}

// GetObjCClasses returns an array of Objective-C classes
func (f *File) GetObjCClasses() ([]objc.Class, error) {
	var classes []objc.Class

	for _, s := range f.Segments() {
		if strings.HasPrefix(s.Name, "__DATA") {
			if sec := f.Section(s.Name, "__objc_classlist"); sec != nil { // An array of pointers to ObjC classes
				if err := f.cr.SeekToAddr(sec.Addr); err != nil {
					return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
				}

				dat := make([]byte, sec.Size)
				if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
					return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
				}

				ptrs := make([]uint64, sec.Size/f.pointerSize())
				if err := binary.Read(bytes.NewReader(dat), f.ByteOrder, &ptrs); err != nil {
					return nil, fmt.Errorf("failed to read %s pointers: %v", sec.Name, err)
				}

				for _, ptr := range ptrs {
					if c, ok := f.GetObjC(f.vma.Convert(ptr)); ok {
						classes = append(classes, *c.(*objc.Class))
					} else {
						class, err := f.GetObjCClass2(f.vma.Convert(ptr))
						if err != nil {
							if f.HasFixups() {
								bindName, err := f.GetBindName(ptr)
								if err == nil {
									class = &objc.Class{Name: strings.TrimPrefix(bindName, "_OBJC_CLASS_$_")}
								} else {
									return nil, fmt.Errorf("failed to read objc_class_t at vmaddr %#x: %v", ptr, err)
								}
							} else {
								return nil, fmt.Errorf("failed to read objc_class_t at vmaddr %#x: %v", ptr, err)
							}
						}
						classes = append(classes, *class)
						f.PutObjC(ptr, class)
					}
				}
			}
		}
	}

	return classes, nil
}

// GetObjCNonLazyClasses returns an array of Objective-C classes that implement +load
func (f *File) GetObjCNonLazyClasses() ([]objc.Class, error) {
	var classes []objc.Class

	for _, s := range f.Segments() {
		if strings.HasPrefix(s.Name, "__DATA") {
			if sec := f.Section(s.Name, "__objc_nlclslist"); sec != nil { // An array of pointers to classes who implement +load
				if err := f.cr.SeekToAddr(sec.Addr); err != nil {
					return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
				}
				dat := make([]byte, sec.Size)
				if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
					return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
				}

				ptrs := make([]uint64, sec.Size/f.pointerSize())
				if err := binary.Read(bytes.NewReader(dat), f.ByteOrder, &ptrs); err != nil {
					return nil, fmt.Errorf("failed to read %s pointers: %v", sec.Name, err)
				}

				for _, ptr := range ptrs {
					ptr = f.vma.Convert(ptr)
					if c, ok := f.GetObjC(ptr); ok {
						classes = append(classes, *c.(*objc.Class))
					} else {
						class, err := f.GetObjCClass2(ptr)
						if err != nil {
							return nil, fmt.Errorf("failed to read non-lazy objc_class_t at vmaddr %#x: %v", ptr, err)
						}
						classes = append(classes, *class)
						f.PutObjC(ptr, class)
					}
				}
			}
		}
	}

	return classes, nil
}

func (f *File) disablePreattachedCategories(vmaddr uint64) (uint64, error) {
	if (vmaddr & 1) != 0 { // has preattached categories
		if err := f.cr.SeekToAddr(vmaddr & 0xFFFFFFFFFFFFFFFE); err != nil {
			return 0, fmt.Errorf("failed to seek to entry_list_t at %#x: %v", vmaddr&0xFFFFFFFFFFFFFFFE, err)
		}

		var entryList objc.EntryList
		if err := binary.Read(f.cr, f.ByteOrder, &entryList); err != nil {
			return 0, fmt.Errorf("failed to read entry_list_t at %#x: %v", vmaddr&0xFFFFFFFFFFFFFFFE, err)
		}

		entries := make([]objc.Entry, entryList.Count)
		if err := binary.Read(f.cr, f.ByteOrder, &entries); err != nil {
			return 0, fmt.Errorf("failed to read entries[entry_count]: %v", err)
		}

		curr := (vmaddr & 0xFFFFFFFFFFFFFFFE) + uint64(binary.Size(entryList))

		var mladdrs []uint64
		for idx, entry := range entries {
			mladdrs = append(mladdrs, uint64(int64(curr)+int64(idx*binary.Size(entry))+entry.MethodListOffset()))
		}

		return mladdrs[len(mladdrs)-1], nil
	}
	return vmaddr, nil
}

// GetObjCClass parses an Objective-C class at a given virtual memory address
func (f *File) GetObjCClass(vmaddr uint64) (*objc.Class, error) {

	if c, ok := f.GetObjC(vmaddr); ok {
		return c.(*objc.Class), nil
	}

	var classPtr objc.SwiftClassMetadata64

	if err := f.cr.SeekToAddr(vmaddr); err != nil {
		return nil, fmt.Errorf("failed to seek to addr %#x: %v", vmaddr, err)
	}

	if err := binary.Read(f.cr, f.ByteOrder, &classPtr); err != nil {
		return nil, fmt.Errorf("failed to read %T: %v", classPtr, err)
	}

	classPtr.IsaVMAddr = f.vma.Convert(classPtr.IsaVMAddr)
	classPtr.SuperclassVMAddr = f.vma.Convert(classPtr.SuperclassVMAddr)
	classPtr.MethodCacheBuckets = f.vma.Convert(classPtr.MethodCacheBuckets)
	classPtr.MethodCacheProperties = f.vma.Convert(classPtr.MethodCacheProperties)
	classPtr.DataVMAddrAndFastFlags = f.vma.Convert(classPtr.DataVMAddrAndFastFlags)

	info, err := f.GetObjCClassInfo(classPtr.DataVMAddrAndFastFlags & objc.FAST_DATA_MASK64)
	if err != nil {
		return nil, fmt.Errorf("failed to get class info at vmaddr: %#x; %v", classPtr.DataVMAddrAndFastFlags&objc.FAST_DATA_MASK64, err)
	}

	name, err := f.GetCString(info.NameVMAddr)
	if err != nil {
		return nil, fmt.Errorf("failed to read cstring: %v", err)
	}

	var methods []objc.Method
	if info.BaseMethodsVMAddr > 0 {
		info.BaseMethodsVMAddr, err = f.disablePreattachedCategories(info.BaseMethodsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to disable preattached categories: %v", err)
		}
		methods, err = f.GetObjCMethods(info.BaseMethodsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to get methods at vmaddr: %#x; %v", info.BaseMethodsVMAddr, err)
		}
	}

	var prots []objc.Protocol
	if info.BaseProtocolsVMAddr > 0 {
		info.BaseProtocolsVMAddr, err = f.disablePreattachedCategories(info.BaseProtocolsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to disable preattached categories: %v", err)
		}
		prots, err = f.parseObjcProtocolList(info.BaseProtocolsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to read protocols vmaddr: %v", err)
		}
	}

	var ivars []objc.Ivar
	if info.IvarsVMAddr > 0 {
		ivars, err = f.GetObjCIvars(info.IvarsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to get ivars at vmaddr: %#x; %v", info.IvarsVMAddr, err)
		}
	}

	var props []objc.Property
	if info.BasePropertiesVMAddr > 0 {
		info.BasePropertiesVMAddr, err = f.disablePreattachedCategories(info.BasePropertiesVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to disable preattached categories: %v", err)
		}
		props, err = f.GetObjCProperties(info.BasePropertiesVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to get props at vmaddr: %#x; %v", info.BasePropertiesVMAddr, err)
		}
	}

	superClass := &objc.Class{}
	if classPtr.SuperclassVMAddr > 0 {
		if info.Flags.IsRoot() {
			superClass = &objc.Class{Name: "<ROOT>"}
		} else if info.Flags.IsMeta() {
			superClass = &objc.Class{Name: "<META>"}
			// } else if info.Flags > 0 {
		} else {
			if c, ok := f.GetObjC(classPtr.SuperclassVMAddr); ok {
				superClass = c.(*objc.Class)
			} else {
				superClass, err = f.GetObjCClass(classPtr.SuperclassVMAddr)
				if err != nil {
					if f.HasFixups() {
						bindName, err := f.GetBindName(classPtr.SuperclassVMAddr)
						if err == nil {
							superClass = &objc.Class{Name: strings.TrimPrefix(bindName, "_OBJC_CLASS_$_")}
						} else {
							return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", vmaddr, err)
						}
					} else {
						superClass = &objc.Class{}
					}
				}
				f.PutObjC(classPtr.SuperclassVMAddr, superClass)
			}
		}
	} else {
		bind, err := f.GetBindName(vmaddr + uint64(unsafe.Offsetof(classPtr.SuperclassVMAddr)))
		if err == nil {
			if info.Flags.IsRoot() {
				superClass = &objc.Class{Name: bind}
			} else if info.Flags.IsMeta() {
				superClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_METACLASS_$_")}
			} else {
				superClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_CLASS_$_")}
			}
		}
	}

	isaClass := &objc.Class{}
	var cMethods []objc.Method
	if classPtr.IsaVMAddr > 0 {
		if !info.Flags.IsMeta() {
			if c, ok := f.GetObjC(classPtr.IsaVMAddr); ok {
				isaClass = c.(*objc.Class)
				cMethods = isaClass.InstanceMethods
			} else {
				isaClass, err = f.GetObjCClass(classPtr.IsaVMAddr)
				if err != nil {
					if f.HasFixups() {
						bindName, err := f.GetBindName(classPtr.IsaVMAddr)
						if err == nil {
							isaClass = &objc.Class{Name: strings.TrimPrefix(bindName, "_OBJC_CLASS_$_")}
						} else {
							return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", vmaddr, err)
						}
					} else {
						isaClass = &objc.Class{}
					}
				} else {
					if isaClass.ReadOnlyData.Flags.IsMeta() {
						cMethods = isaClass.InstanceMethods
					}
				}
				f.PutObjC(classPtr.IsaVMAddr, isaClass)
			}
		}
	} else {
		bind, err := f.GetBindName(vmaddr + uint64(unsafe.Offsetof(classPtr.IsaVMAddr)))
		if err == nil {
			if info.Flags.IsRoot() {
				isaClass = &objc.Class{Name: bind}
			} else if info.Flags.IsMeta() {
				isaClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_METACLASS_$_")}
			} else {
				isaClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_CLASS_$_")}
			}
		}
	}

	return &objc.Class{
		Name:                  name,
		SuperClass:            superClass.Name,
		Isa:                   isaClass.Name,
		InstanceMethods:       methods,
		ClassMethods:          cMethods,
		Ivars:                 ivars,
		Props:                 props,
		Protocols:             prots,
		ClassPtr:              f.rebasePtr(vmaddr),
		IsaVMAddr:             classPtr.IsaVMAddr,
		SuperclassVMAddr:      classPtr.SuperclassVMAddr,
		MethodCacheBuckets:    classPtr.MethodCacheBuckets,
		MethodCacheProperties: classPtr.MethodCacheProperties,
		DataVMAddr:            classPtr.DataVMAddrAndFastFlags & objc.FAST_DATA_MASK64,
		IsSwiftLegacy:         (classPtr.DataVMAddrAndFastFlags&objc.FAST_IS_SWIFT_LEGACY == 1),
		IsSwiftStable:         (classPtr.DataVMAddrAndFastFlags&objc.FAST_IS_SWIFT_STABLE == 1),
		ReadOnlyData:          *info,
	}, nil
}

// TODO: get rid of old GetObjCClass
// GetObjCClass parses an Objective-C class at a given virtual memory address
func (f *File) GetObjCClass2(vmaddr uint64) (*objc.Class, error) {

	if c, ok := f.GetObjC(vmaddr); ok {
		return c.(*objc.Class), nil
	}

	var classPtr objc.SwiftClassMetadata64
	// var classSuperclassVMAddr uint64
	// var classDataVMAddr uint64

	if err := f.cr.SeekToAddr(vmaddr); err != nil {
		return nil, fmt.Errorf("failed to seek to addr %#x: %v", vmaddr, err)
	}

	if err := binary.Read(f.cr, f.ByteOrder, &classPtr); err != nil {
		return nil, fmt.Errorf("failed to read %T: %v", classPtr, err)
	}

	classPtr.IsaVMAddr = f.vma.Convert(classPtr.IsaVMAddr)
	classPtr.SuperclassVMAddr = f.vma.Convert(classPtr.SuperclassVMAddr)
	classPtr.MethodCacheProperties = f.vma.Convert(classPtr.MethodCacheProperties)
	classPtr.DataVMAddrAndFastFlags = f.vma.Convert(classPtr.DataVMAddrAndFastFlags)

	info, err := f.GetObjCClassInfo(classPtr.DataVMAddrAndFastFlags & objc.FAST_DATA_MASK64)
	if err != nil {
		return nil, fmt.Errorf("failed to get class info at vmaddr: %#x; %v", classPtr.DataVMAddrAndFastFlags&objc.FAST_DATA_MASK64, err)
	}

	name, err := f.GetCString(info.NameVMAddr)
	if err != nil {
		return nil, fmt.Errorf("failed to read cstring: %v", err)
	}

	var methods []objc.Method
	if info.BaseMethodsVMAddr > 0 {
		info.BaseMethodsVMAddr, err = f.disablePreattachedCategories(info.BaseMethodsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to disable preattached categories: %v", err)
		}
		methods, err = f.GetObjCMethods(info.BaseMethodsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to get methods at vmaddr: %#x; %v", info.BaseMethodsVMAddr, err)
		}
	}

	var prots []objc.Protocol
	if info.BaseProtocolsVMAddr > 0 {
		info.BaseProtocolsVMAddr, err = f.disablePreattachedCategories(info.BaseProtocolsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to disable preattached categories: %v", err)
		}
		prots, err = f.parseObjcProtocolList(info.BaseProtocolsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to read protocols vmaddr: %v", err)
		}
	}

	var ivars []objc.Ivar
	if info.IvarsVMAddr > 0 {
		ivars, err = f.GetObjCIvars(info.IvarsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to get ivars at vmaddr: %#x; %v", info.IvarsVMAddr, err)
		}
	}

	var props []objc.Property
	if info.BasePropertiesVMAddr > 0 {
		info.BasePropertiesVMAddr, err = f.disablePreattachedCategories(info.BasePropertiesVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to disable preattached categories: %v", err)
		}
		props, err = f.GetObjCProperties(info.BasePropertiesVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to get props at vmaddr: %#x; %v", info.BasePropertiesVMAddr, err)
		}
	}

	superClass := &objc.Class{}
	if classPtr.SuperclassVMAddr > 0 {
		if info.Flags.IsRoot() {
			superClass = &objc.Class{Name: "<ROOT>"}
		} else if info.Flags.IsMeta() {
			superClass = &objc.Class{Name: "<META>"}
			// } else if info.Flags > 0 {
		} else {
			if c, ok := f.GetObjC(classPtr.SuperclassVMAddr); ok {
				superClass = c.(*objc.Class)
			} else {
				superClass, err = f.GetObjCClass2(classPtr.SuperclassVMAddr)
				if err != nil {
					if f.HasFixups() {
						bindName, err := f.GetBindName(classPtr.SuperclassVMAddr)
						if err == nil {
							superClass = &objc.Class{Name: strings.TrimPrefix(bindName, "_OBJC_CLASS_$_")}
						} else {
							return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", vmaddr, err)
						}
					} else {
						superClass = &objc.Class{}
					}
				}
				f.PutObjC(classPtr.SuperclassVMAddr, superClass)
			}
		}
	} else {
		bind, err := f.GetBindName(vmaddr + uint64(unsafe.Offsetof(classPtr.SuperclassVMAddr)))
		if err == nil {
			if info.Flags.IsRoot() {
				superClass = &objc.Class{Name: bind}
			} else if info.Flags.IsMeta() {
				superClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_METACLASS_$_")}
			} else {
				superClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_CLASS_$_")}
			}
		}
	}

	isaClass := &objc.Class{}
	var cMethods []objc.Method
	if classPtr.IsaVMAddr > 0 {
		if !info.Flags.IsMeta() {
			if c, ok := f.GetObjC(classPtr.IsaVMAddr); ok {
				isaClass = c.(*objc.Class)
				cMethods = isaClass.InstanceMethods
			} else {
				isaClass, err = f.GetObjCClass(classPtr.IsaVMAddr)
				if err != nil {
					if f.HasFixups() {
						bindName, err := f.GetBindName(classPtr.IsaVMAddr)
						if err == nil {
							isaClass = &objc.Class{Name: strings.TrimPrefix(bindName, "_OBJC_CLASS_$_")}
						} else {
							return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", vmaddr, err)
						}
					} else {
						isaClass = &objc.Class{}
					}
				} else {
					if isaClass.ReadOnlyData.Flags.IsMeta() {
						cMethods = isaClass.InstanceMethods
					}
				}
				f.PutObjC(classPtr.IsaVMAddr, isaClass)
			}
		}
	} else {
		bind, err := f.GetBindName(vmaddr + uint64(unsafe.Offsetof(classPtr.IsaVMAddr)))
		if err == nil {
			if info.Flags.IsRoot() {
				isaClass = &objc.Class{Name: bind}
			} else if info.Flags.IsMeta() {
				isaClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_METACLASS_$_")}
			} else {
				isaClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_CLASS_$_")}
			}
		}
	}

	return &objc.Class{
		Name:                  name,
		SuperClass:            superClass.Name,
		Isa:                   isaClass.Name,
		InstanceMethods:       methods,
		ClassMethods:          cMethods,
		Ivars:                 ivars,
		Props:                 props,
		Protocols:             prots,
		ClassPtr:              f.rebasePtr(vmaddr),
		IsaVMAddr:             classPtr.IsaVMAddr,
		SuperclassVMAddr:      classPtr.SuperclassVMAddr,
		MethodCacheBuckets:    classPtr.MethodCacheBuckets,
		MethodCacheProperties: classPtr.MethodCacheProperties,
		DataVMAddr:            classPtr.DataVMAddrAndFastFlags & objc.FAST_DATA_MASK64,
		IsSwiftLegacy:         (classPtr.DataVMAddrAndFastFlags&objc.FAST_IS_SWIFT_LEGACY != 0),
		IsSwiftStable:         (classPtr.DataVMAddrAndFastFlags&objc.FAST_IS_SWIFT_STABLE != 0),
		ReadOnlyData:          *info,
	}, nil
}

// GetObjCCategories returns an array of Objective-C categories by parsing the __objc_catlist data
func (f *File) GetObjCCategories() ([]objc.Category, error) {
	var categoryPtr objc.CategoryT
	var categories []objc.Category

	for _, s := range f.Segments() {
		if strings.HasPrefix(s.Name, "__DATA") {
			if sec := f.Section(s.Name, "__objc_catlist"); sec != nil { // List of ObjC categories
				if err := f.cr.SeekToAddr(sec.Addr); err != nil {
					return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
				}

				dat := make([]byte, sec.Size)
				if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
					return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
				}
				ptrs := make([]uint64, sec.Size/f.pointerSize())
				if err := binary.Read(bytes.NewReader(dat), f.ByteOrder, &ptrs); err != nil {
					return nil, fmt.Errorf("failed to read %s.%s pointers: %v", sec.Seg, sec.Name, err)
				}

				for _, ptr := range ptrs {
					ptr = f.vma.Convert(ptr)

					off, err := f.vma.GetOffset(ptr)
					if err != nil {
						return nil, fmt.Errorf("failed to convert vmaddr: %v", err)
					}
					f.cr.Seek(int64(off), io.SeekStart)

					if err := binary.Read(f.cr, f.ByteOrder, &categoryPtr); err != nil {
						return nil, fmt.Errorf("failed to read %T: %v", categoryPtr, err)
					}

					category := objc.Category{VMAddr: f.rebasePtr(ptr), Class: &objc.Class{}}

					categoryPtr.NameVMAddr = f.vma.Convert(categoryPtr.NameVMAddr)
					category.Name, err = f.GetCString(categoryPtr.NameVMAddr)
					if err != nil {
						return nil, fmt.Errorf("failed to read cstring: %v", err)
					}
					if categoryPtr.ClsVMAddr > 0 {
						categoryPtr.ClsVMAddr = f.vma.Convert(categoryPtr.ClsVMAddr)
						if c, ok := f.objc[categoryPtr.ClsVMAddr]; ok {
							category.Class = c.(*objc.Class)
						} else {
							category.Class, err = f.GetObjCClass(categoryPtr.ClsVMAddr)
							if err != nil {
								if f.HasFixups() {
									bindName, err := f.GetBindName(categoryPtr.ClsVMAddr)
									if err != nil {
										if !errors.Is(err, ErrMachONoBindInfo) {
											return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", categoryPtr.ClsVMAddr, err)
										}
									} else {
										category.Class = &objc.Class{Name: strings.TrimPrefix(bindName, "_OBJC_CLASS_$_")}
									}
								}
							}
							f.PutObjC(categoryPtr.ClsVMAddr, category.Class)
						}
					} else {
						if c, ok := f.objc[categoryPtr.ClsVMAddr]; ok {
							category.Class = c.(*objc.Class)
						} else {
							category.Class = &objc.Class{}
							bindName, err := f.GetBindName(ptr + uint64(unsafe.Offsetof(categoryPtr.ClsVMAddr)))
							if err != nil {
								if !errors.Is(err, ErrMachONoBindInfo) {
									return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", ptr+uint64(unsafe.Offsetof(categoryPtr.ClsVMAddr)), err)
								}
							} else {
								category.Class = &objc.Class{Name: strings.TrimPrefix(bindName, "_OBJC_CLASS_$_")}
								f.PutObjC(ptr+uint64(unsafe.Offsetof(categoryPtr.ClsVMAddr)), category.Class)
							}
						}
					}
					if categoryPtr.InstanceMethodsVMAddr > 0 {
						categoryPtr.InstanceMethodsVMAddr = f.vma.Convert(categoryPtr.InstanceMethodsVMAddr)
						category.InstanceMethods, err = f.GetObjCMethods(categoryPtr.InstanceMethodsVMAddr)
						if err != nil {
							return nil, fmt.Errorf("failed to get instance methods at vmaddr: %#x; %v", categoryPtr.InstanceMethodsVMAddr, err)
						}
					}
					if categoryPtr.ClassMethodsVMAddr > 0 {
						categoryPtr.ClassMethodsVMAddr = f.vma.Convert(categoryPtr.ClassMethodsVMAddr)
						category.ClassMethods, err = f.GetObjCMethods(categoryPtr.ClassMethodsVMAddr)
						if err != nil {
							return nil, fmt.Errorf("failed to get class methods at vmaddr: %#x; %v", categoryPtr.ClassMethodsVMAddr, err)
						}
					}
					if categoryPtr.ProtocolsVMAddr > 0 {
						categoryPtr.ProtocolsVMAddr = f.vma.Convert(categoryPtr.ProtocolsVMAddr)
						category.Protocols, err = f.parseObjcProtocolList(categoryPtr.ProtocolsVMAddr)
						if err != nil {
							return nil, fmt.Errorf("failed to read protocols vmaddr: %v", err)
						}
					}
					if categoryPtr.InstancePropertiesVMAddr > 0 {
						categoryPtr.InstancePropertiesVMAddr = f.vma.Convert(categoryPtr.InstancePropertiesVMAddr)
						category.Properties, err = f.GetObjCProperties(categoryPtr.InstancePropertiesVMAddr)
						if err != nil {
							return nil, fmt.Errorf("failed to get class methods at vmaddr: %#x; %v", categoryPtr.ClassMethodsVMAddr, err)
						}
					}

					category.CategoryT = categoryPtr
					categories = append(categories, category)
				}
			}
		}
	}

	return categories, nil
}

// GetObjCNonLazyCategories returns an array of Objective-C classes that implement +load
func (f *File) GetObjCNonLazyCategories() ([]objc.Category, error) {
	var cats []objc.Category

	for _, s := range f.Segments() {
		if strings.HasPrefix(s.Name, "__DATA") {
			if sec := f.Section(s.Name, "__objc_nlcatlist"); sec != nil { // An array of pointers to classes who implement +load
				if err := f.cr.SeekToAddr(sec.Addr); err != nil {
					return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
				}
				dat := make([]byte, sec.Size)
				if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
					return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
				}

				ptrs := make([]uint64, sec.Size/f.pointerSize())
				if err := binary.Read(bytes.NewReader(dat), f.ByteOrder, &ptrs); err != nil {
					return nil, fmt.Errorf("failed to read %s pointers: %v", sec.Name, err)
				}

				for _, ptr := range ptrs {
					ptr = f.vma.Convert(ptr)
					if c, ok := f.GetObjC(ptr); ok {
						cats = append(cats, *c.(*objc.Category))
					} else {
						cat, err := f.parseCategory(ptr)
						if err != nil {
							return nil, fmt.Errorf("failed to read non-lazy category_t at vmaddr %#x: %v", ptr, err)
						}
						cats = append(cats, *cat)
						f.PutObjC(ptr, cat)
					}
				}
			}
		}
	}

	return cats, nil
}

func (f *File) parseCategory(vmaddr uint64) (*objc.Category, error) {

	if err := f.cr.SeekToAddr(vmaddr); err != nil {
		return nil, fmt.Errorf("failed to seek to objc category vmaddr: %#x; %v", vmaddr, err)
	}

	var categoryPtr objc.CategoryT
	if err := binary.Read(f.cr, f.ByteOrder, &categoryPtr); err != nil {
		return nil, fmt.Errorf("failed to read %T: %v", categoryPtr, err)
	}

	categoryPtr.NameVMAddr = f.vma.Convert(categoryPtr.NameVMAddr)
	categoryPtr.ClsVMAddr = f.vma.Convert(categoryPtr.ClsVMAddr)
	categoryPtr.InstanceMethodsVMAddr = f.vma.Convert(categoryPtr.InstanceMethodsVMAddr)
	categoryPtr.ClassMethodsVMAddr = f.vma.Convert(categoryPtr.ClassMethodsVMAddr)
	categoryPtr.ProtocolsVMAddr = f.vma.Convert(categoryPtr.ProtocolsVMAddr)
	categoryPtr.InstancePropertiesVMAddr = f.vma.Convert(categoryPtr.InstancePropertiesVMAddr)

	name, err := f.GetCString(categoryPtr.NameVMAddr)
	if err != nil {
		return nil, fmt.Errorf("failed to read cstring: %v", err)
	}

	return &objc.Category{
		Name:      name,
		VMAddr:    f.rebasePtr(vmaddr),
		CategoryT: categoryPtr,
	}, nil
}

func (f *File) parseObjcProtocolList(vmaddr uint64) ([]objc.Protocol, error) {
	var protocols []objc.Protocol

	if err := f.cr.SeekToAddr(vmaddr); err != nil {
		return nil, fmt.Errorf("failed to seek to objc protocol list vmaddr: %#x; %v", vmaddr, err)
	}

	var protList objc.ProtocolList
	if err := binary.Read(f.cr, f.ByteOrder, &protList.Count); err != nil {
		return nil, fmt.Errorf("failed to read protocol_list_t count: %v", err)
	}

	protList.Protocols = make([]uint64, protList.Count)
	if err := binary.Read(f.cr, f.ByteOrder, &protList.Protocols); err != nil {
		return nil, fmt.Errorf("failed to read protocol_list_t prots: %v", err)
	}

	for _, protPtr := range protList.Protocols {
		prot, err := f.getObjcProtocol(f.vma.Convert(protPtr))
		if err != nil {
			return nil, err
		}
		protocols = append(protocols, *prot)
	}

	return protocols, nil
}

func (f *File) getObjcProtocol(vmaddr uint64) (proto *objc.Protocol, err error) {
	var protoPtr objc.ProtocolT

	if err := f.cr.SeekToAddr(vmaddr); err != nil {
		return nil, fmt.Errorf("failed to seek to objc protocol vmaddr: %#x; %v", vmaddr, err)
	}

	if err := binary.Read(f.cr, f.ByteOrder, &protoPtr); err != nil {
		return nil, fmt.Errorf("failed to read protocol_t: %v", err)
	}

	proto = &objc.Protocol{Ptr: f.rebasePtr(vmaddr)}

	if protoPtr.NameVMAddr > 0 {
		protoPtr.NameVMAddr = f.vma.Convert(protoPtr.NameVMAddr)
		proto.Name, err = f.GetCString(protoPtr.NameVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to read cstring: %v", err)
		}
	}
	if protoPtr.IsaVMAddr > 0 {
		protoPtr.IsaVMAddr = f.vma.Convert(protoPtr.IsaVMAddr)
		if c, ok := f.GetObjC(protoPtr.IsaVMAddr); ok {
			proto.Isa = c.(*objc.Class)
		} else {
			// FIXME: causes infinite loop
			// proto.Isa, err = f.GetObjCClass(protoPtr.IsaVMAddr)
			// if err != nil {
			// 	return nil, fmt.Errorf("failed to get class at vmaddr: %#x; %v", protoPtr.IsaVMAddr, err)
			// }
			// f.objc[protoPtr.IsaVMAddr] = proto.Isa
		}
	}
	if protoPtr.ProtocolsVMAddr > 0 {
		protoPtr.ProtocolsVMAddr = f.vma.Convert(protoPtr.ProtocolsVMAddr)
		proto.Prots, err = f.parseObjcProtocolList(protoPtr.ProtocolsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to read protocols vmaddr: %v", err)
		}
	}
	if protoPtr.InstanceMethodsVMAddr > 0 {
		protoPtr.InstanceMethodsVMAddr = f.vma.Convert(protoPtr.InstanceMethodsVMAddr)
		proto.InstanceMethods, err = f.GetObjCMethods(protoPtr.InstanceMethodsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to read instance method vmaddr: %v", err)
		}
	}
	if protoPtr.OptionalInstanceMethodsVMAddr > 0 {
		protoPtr.OptionalInstanceMethodsVMAddr = f.vma.Convert(protoPtr.OptionalInstanceMethodsVMAddr)
		proto.OptionalInstanceMethods, err = f.GetObjCMethods(protoPtr.OptionalInstanceMethodsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to read optional instance method vmaddr: %v", err)
		}
	}
	if protoPtr.ClassMethodsVMAddr > 0 {
		protoPtr.ClassMethodsVMAddr = f.vma.Convert(protoPtr.ClassMethodsVMAddr)
		proto.ClassMethods, err = f.GetObjCMethods(protoPtr.ClassMethodsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to read class method vmaddr: %v", err)
		}
	}
	if protoPtr.OptionalClassMethodsVMAddr > 0 {
		protoPtr.OptionalClassMethodsVMAddr = f.vma.Convert(protoPtr.OptionalClassMethodsVMAddr)
		proto.OptionalClassMethods, err = f.GetObjCMethods(protoPtr.OptionalClassMethodsVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to read optional class method vmaddr: %v", err)
		}
	}
	if protoPtr.InstancePropertiesVMAddr > 0 {
		protoPtr.InstancePropertiesVMAddr = f.vma.Convert(protoPtr.InstancePropertiesVMAddr)
		proto.InstanceProperties, err = f.GetObjCProperties(protoPtr.InstancePropertiesVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to read instance property vmaddr: %v", err)
		}
	}
	if protoPtr.ExtendedMethodTypesVMAddr > 0 {
		protoPtr.ExtendedMethodTypesVMAddr = f.vma.Convert(protoPtr.ExtendedMethodTypesVMAddr)
		off, err := f.vma.GetOffset(protoPtr.ExtendedMethodTypesVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to convert vmaddr: %v", err)
		}
		f.cr.Seek(int64(off), io.SeekStart)

		var extMPtr uint64
		if err := binary.Read(f.cr, f.ByteOrder, &extMPtr); err != nil {
			return nil, fmt.Errorf("failed to read ExtendedMethodTypesVMAddr: %v", err)
		}

		proto.ExtendedMethodTypes, err = f.GetCString(f.vma.Convert(extMPtr))
		if err != nil {
			return nil, fmt.Errorf("failed to read proto extended method types cstring: %v", err)
		}
	}
	if protoPtr.DemangledNameVMAddr > 0 {
		protoPtr.DemangledNameVMAddr = f.vma.Convert(protoPtr.DemangledNameVMAddr)
		proto.DemangledName, err = f.GetCString(protoPtr.DemangledNameVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to read proto demangled name cstring: %v", err)
		}
	}

	proto.ProtocolT = protoPtr

	return proto, nil
}

// GetObjCProtocols returns the Objective-C protocols
func (f *File) GetObjCProtocols() ([]objc.Protocol, error) {

	var protocols []objc.Protocol

	for _, s := range f.Segments() {
		if strings.HasPrefix(s.Name, "__DATA") {
			if sec := f.Section(s.Name, "__objc_protolist"); sec != nil {
				if err := f.cr.SeekToAddr(sec.Addr); err != nil {
					return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
				}

				dat := make([]byte, sec.Size)
				if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
					return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
				}

				ptrs := make([]uint64, sec.Size/f.pointerSize())
				if err := binary.Read(bytes.NewReader(dat), f.ByteOrder, &ptrs); err != nil {
					return nil, fmt.Errorf("failed to read %s.%s pointers: %v", sec.Seg, sec.Name, err)
				}

				for _, ptr := range ptrs {
					proto, err := f.getObjcProtocol(f.vma.Convert(ptr))
					if err != nil {
						return nil, fmt.Errorf("failed to read protocol at pointer %#x (converted %#x); %v", ptr, f.vma.Convert(ptr), err)
					}
					protocols = append(protocols, *proto)
				}
			}
		}
	}
	return protocols, nil
}

func (f *File) GetObjCMethods(vmaddr uint64) ([]objc.Method, error) {
	if c, ok := f.GetObjC(vmaddr); ok {
		return c.([]objc.Method), nil
	}

	var methods []objc.Method

	if err := f.forEachObjCMethod(vmaddr, func(u uint64, m objc.Method, b *bool) {
		methods = append(methods, m)
	}); err != nil {
		return nil, fmt.Errorf("failed to read methods at vmaddr %#x: %v", vmaddr, err)
	}

	f.PutObjC(vmaddr, methods)

	return methods, nil
}

// GetObjCMethodLists parses the method lists in the __objc_methlist section
func (f *File) GetObjCMethodLists() ([]objc.Method, error) {
	var methods []objc.Method
	var methodList objc.MethodList
	var nextMethodListOffset uint64

	if sec := f.Section("__TEXT", "__objc_methlist"); sec != nil {
		if err := f.cr.SeekToAddr(sec.Addr); err != nil {
			return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
		}

		dat := make([]byte, sec.Size)
		if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
			return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
		}

		r := bytes.NewReader(dat)

		var mladdrs []uint64

		for {
			currOffset, _ := r.Seek(0, io.SeekCurrent)
			currAddr := sec.Addr + uint64(currOffset)

			err := binary.Read(r, f.ByteOrder, &methodList)
			if err == io.EOF {
				break
			}
			if err != nil {
				return nil, fmt.Errorf("failed to read method_list_t: %v", err)
			}

			mladdrs = append(mladdrs, currAddr)
			currOffset, _ = r.Seek(0, io.SeekCurrent)

			if methodList.UsesRelativeOffsets() {
				nextMethodListOffset = uint64(currOffset + int64(methodList.Count)*int64(binary.Size(objc.RelativeMethodT{})))
				nextMethodListOffset += nextMethodListOffset % f.pointerSize() // pointer align
			} else {
				nextMethodListOffset = uint64(currOffset + int64(methodList.Count)*int64(binary.Size(objc.MethodT{})))
				nextMethodListOffset += nextMethodListOffset % f.pointerSize() // pointer align
			}
			r.Seek(int64(nextMethodListOffset), io.SeekStart) // skip to next method_list_t
		}

		for _, mladdr := range mladdrs {
			if err := f.forEachObjCMethod(mladdr, func(u uint64, m objc.Method, b *bool) {
				methods = append(methods, m)
			}); err != nil {
				return nil, fmt.Errorf("failed to read methods for method_list_t at vmaddr %#x: %v", mladdr, err)
			}
		}
	} else {
		return nil, fmt.Errorf("macho does not contain __objc_methlist section: %w", ErrObjcSectionNotFound)
	}

	return methods, nil
}

func (f *File) forEachObjCMethod(methodListVMAddr uint64, handler func(uint64, objc.Method, *bool)) error {
	var err error
	var methodList objc.MethodList

	if err := f.cr.SeekToAddr(methodListVMAddr); err != nil {
		return fmt.Errorf("failed to seek to method_list_t at %#x: %v", methodListVMAddr, err)
	}

	if err := binary.Read(f.cr, f.ByteOrder, &methodList); err != nil {
		return fmt.Errorf("failed to read method_list_t at %#x: %v", methodListVMAddr, err)
	}

	if methodList.UsesRelativeOffsets() {
		methodListArrayBaseVMAddr := methodListVMAddr + uint64(binary.Size(methodList))
		methods := make([]objc.RelativeMethodT, methodList.Count)
		if err := binary.Read(f.cr, f.ByteOrder, &methods); err != nil {
			return fmt.Errorf("failed to read relative_method_t: %v", err)
		}

		for idx, m := range methods {
			methodVMAddr := int64(methodListArrayBaseVMAddr) + int64(uint32(idx)*methodList.EntSize())

			method := objc.Method{}

			if methodList.UsesDirectOffsetsToSelectors() {
				if f.sharedCacheRelativeSelectorBaseVMAddress != 0 {
					method.NameVMAddr = uint64(int64(f.sharedCacheRelativeSelectorBaseVMAddress) + int64(m.NameOffset))
				} else {
					method.NameVMAddr = uint64(methodVMAddr + int64(m.NameOffset))
				}
			} else {
				nameVMAddr := uint64(methodVMAddr + int64(m.NameOffset))
				method.NameVMAddr, err = f.GetPointerAtAddress(nameVMAddr)
				if err != nil {
					return fmt.Errorf("failed to read relative_method_t name pointer: %v", err)
				}
			}

			method.NameLocationVMAddr = uint64(methodVMAddr+int64(m.NameOffset)) + uint64(unsafe.Offsetof(m.NameOffset))
			method.TypesVMAddr = uint64(methodVMAddr+int64(m.TypesOffset)) + uint64(unsafe.Offsetof(m.TypesOffset))
			method.ImpVMAddr = uint64(methodVMAddr+int64(m.ImpOffset)) + uint64(unsafe.Offsetof(m.ImpOffset))

			method.Name, err = f.GetCString(method.NameVMAddr)
			if err != nil {
				return fmt.Errorf("failed to read relative_method_t name cstring: %v", err)
			}
			method.Types, err = f.GetCString(method.TypesVMAddr)
			if err != nil {
				return fmt.Errorf("failed to read relative_method_t types cstring: %v", err)
			}

			stop := false
			handler(uint64(methodVMAddr), method, &stop)
			if stop { // handler requested to halt iteration
				break
			}
		}
	} else {
		currentVMAddr, _ := f.cr.Seek(0, io.SeekCurrent)
		methods := make([]objc.MethodT, methodList.Count)
		if err := binary.Read(f.cr, f.ByteOrder, &methods); err != nil {
			return fmt.Errorf("failed to read method_t(s): %v", err)
		}
		for idx, m := range methods {
			m.NameVMAddr = f.vma.Convert(m.NameVMAddr)
			m.TypesVMAddr = f.vma.Convert(m.TypesVMAddr)
			m.ImpVMAddr = f.vma.Convert(m.ImpVMAddr)
			n, err := f.GetCString(m.NameVMAddr)
			if err != nil {
				return fmt.Errorf("failed to read method_t name cstring: %v", err)
			}
			t, err := f.GetCString(m.TypesVMAddr)
			if err != nil {
				return fmt.Errorf("failed to read method_t types cstring: %v", err)
			}
			stop := false
			handler(uint64(currentVMAddr+int64(idx*binary.Size(m))), objc.Method{
				NameVMAddr:  m.NameVMAddr,
				TypesVMAddr: m.TypesVMAddr,
				ImpVMAddr:   m.ImpVMAddr,
				Name:        n,
				Types:       t,
			}, &stop)
			if stop { // handler requested to halt iteration
				break
			}
		}
	}

	return nil
}

// GetObjCIvars returns the Objective-C instance variables
func (f *File) GetObjCIvars(vmaddr uint64) ([]objc.Ivar, error) {

	var ivarsList objc.IvarList
	var ivars []objc.Ivar

	if err := f.cr.SeekToAddr(vmaddr); err != nil {
		return nil, fmt.Errorf("failed to seek to objc_ivar_list_t at %#x: %v", vmaddr, err)
	}

	if err := binary.Read(f.cr, f.ByteOrder, &ivarsList); err != nil {
		return nil, fmt.Errorf("failed to read objc_ivar_list_t: %v", err)
	}

	ivs := make([]objc.IvarT, ivarsList.Count)
	if err := binary.Read(f.cr, f.ByteOrder, &ivs); err != nil {
		return nil, fmt.Errorf("failed to read objc_ivar_list_t: %v", err)
	}

	// FIXME: what ARE these alignments ?
	// var maxAlignment uint32
	// for _, ivar := range ivs {
	// 	if ivar.Alignment() > maxAlignment {
	// 		maxAlignment = ivar.Alignment()
	// 	}
	// }

	// var diff uint32
	// if maxAlignment > 0 {
	// 	alignMask := maxAlignment - 1
	// 	diff = (diff + alignMask) &^ alignMask
	// }

	for _, ivar := range ivs {
		ivar.Offset = f.vma.Convert(ivar.Offset)
		// ivar.Offset += uint64(diff) // align ivar offsets to max alignment
		ivar.NameVMAddr = f.vma.Convert(ivar.NameVMAddr)
		ivar.TypesVMAddr = f.vma.Convert(ivar.TypesVMAddr)

		if ivar.Offset > 0 {
			if err := f.cr.SeekToAddr(ivar.Offset); err != nil {
				return nil, fmt.Errorf("failed to seek to objc_ivar_list_t at %#x: %v", vmaddr, err)
			}
		}

		var o uint32
		if err := binary.Read(f.cr, f.ByteOrder, &o); err != nil {
			if err == io.EOF {
				o = 0 // I've seen this happen when this points to the zero-filled __DATA __common section
			} else {
				return nil, fmt.Errorf("failed to read ivar.offset: %v", err)
			}
		}
		n, err := f.GetCString(ivar.NameVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to read ivar name cstring: %v", err)
		}
		// if diff > 0 {
		// 	ivar.TypesVMAddr += uint64(diff) // align ivar types to max alignment
		// }
		t, err := f.GetCString(ivar.TypesVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to read ivar types cstring: %v", err)
		}
		ivars = append(ivars, objc.Ivar{
			Name:   n,
			Type:   t,
			Offset: o,
			IvarT:  ivar,
		})
	}

	return ivars, nil
}

// GetObjCProperties returns the Objective-C properties
func (f *File) GetObjCProperties(vmaddr uint64) ([]objc.Property, error) {

	var propList objc.PropertyList
	var objcProperties []objc.Property

	if err := f.cr.SeekToAddr(vmaddr); err != nil {
		return nil, fmt.Errorf("failed to seek to objc_property_list_t at %#x: %v", vmaddr, err)
	}

	if err := binary.Read(f.cr, f.ByteOrder, &propList); err != nil {
		return nil, fmt.Errorf("failed to read objc_property_list_t: %v", err)
	}

	properties := make([]objc.PropertyT, propList.Count)
	if err := binary.Read(f.cr, f.ByteOrder, &properties); err != nil {
		return nil, fmt.Errorf("failed to read objc_property_t: %v", err)
	}

	for _, prop := range properties {
		prop.NameVMAddr = f.vma.Convert(prop.NameVMAddr)
		prop.AttributesVMAddr = f.vma.Convert(prop.AttributesVMAddr)

		name, err := f.GetCString(prop.NameVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to read prop name cstring: %v", err)
		}
		attrib, err := f.GetCString(prop.AttributesVMAddr)
		if err != nil {
			return nil, fmt.Errorf("failed to read prop attributes cstring: %v", err)
		}
		objcProperties = append(objcProperties, objc.Property{
			PropertyT:         prop,
			Name:              name,
			EncodedAttributes: attrib,
		})
	}

	return objcProperties, nil
}

// GetObjCClassReferences returns a map of classes to their section data virtual memory address
func (f *File) GetObjCClassReferences() (map[uint64]*objc.Class, error) {
	clsRefs := make(map[uint64]*objc.Class)

	for _, s := range f.Segments() {
		if strings.HasPrefix(s.Name, "__DATA") {
			if sec := f.Section(s.Name, "__objc_classrefs"); sec != nil { // External references to other classes
				if err := f.cr.SeekToAddr(sec.Addr); err != nil {
					return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
				}

				dat := make([]byte, sec.Size)
				if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
					return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
				}

				classPtrs := make([]uint64, sec.Size/f.pointerSize())
				if err := binary.Read(bytes.NewReader(dat), f.ByteOrder, &classPtrs); err != nil {
					return nil, fmt.Errorf("failed to read %s.%s pointers: %v", sec.Seg, sec.Name, err)
				}

				for idx, ptr := range classPtrs {
					ptr = f.vma.Convert(ptr)
					if c, ok := f.objc[ptr]; ok {
						clsRefs[sec.Addr+uint64(idx*sizeOfInt64)] = c.(*objc.Class)
					} else {
						if cls, err := f.GetObjCClass(ptr); err != nil {
							if f.HasFixups() {
								if bindName, err := f.GetBindName(ptr); err == nil {
									clsRefs[sec.Addr+uint64(idx*sizeOfInt64)] = &objc.Class{Name: strings.TrimPrefix(bindName, "_OBJC_CLASS_$_")}
								} else {
									return nil, fmt.Errorf("failed to read objc_class_t at classref ptr: %#x; %v", ptr, err)
								}
							}
							// TODO: don't swallow error here
						} else {
							clsRefs[sec.Addr+uint64(idx*sizeOfInt64)] = cls
							f.PutObjC(ptr, cls)
						}
					}
				}
			}
		}
	}

	return clsRefs, nil
}

// GetObjCSuperReferences returns a map of super classes to their section data virtual memory address
func (f *File) GetObjCSuperReferences() (map[uint64]*objc.Class, error) {
	clsRefs := make(map[uint64]*objc.Class)

	for _, s := range f.Segments() {
		if strings.HasPrefix(s.Name, "__DATA") {
			if sec := f.Section(s.Name, "__objc_superrefs"); sec != nil { // External references to super classes
				if err := f.cr.SeekToAddr(sec.Addr); err != nil {
					return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
				}

				dat := make([]byte, sec.Size)
				if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
					return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
				}

				classPtrs := make([]uint64, sec.Size/f.pointerSize())
				if err := binary.Read(bytes.NewReader(dat), f.ByteOrder, &classPtrs); err != nil {
					return nil, fmt.Errorf("failed to read %s.%s pointers: %v", sec.Seg, sec.Name, err)
				}

				for idx, ptr := range classPtrs {
					ptr = f.vma.Convert(ptr)
					if c, ok := f.objc[ptr]; ok {
						clsRefs[sec.Addr+uint64(idx*sizeOfInt64)] = c.(*objc.Class)
					} else {
						if cls, err := f.GetObjCClass(ptr); err != nil {
							if f.HasFixups() {
								if bindName, err := f.GetBindName(ptr); err == nil {
									clsRefs[sec.Addr+uint64(idx*sizeOfInt64)] = &objc.Class{Name: strings.TrimPrefix(bindName, "_OBJC_CLASS_$_")}
								} else {
									return nil, fmt.Errorf("failed to read objc_class_t at superref ptr: %#x; %v", ptr, err)
								}
							}
							// TODO: don't swallow error here
						} else {
							clsRefs[sec.Addr+uint64(idx*sizeOfInt64)] = cls
							f.PutObjC(ptr, cls)
						}
					}
				}
			}
		}
	}
	return clsRefs, nil
}

// GetObjCProtoReferences returns a map of protocol names to their section data virtual memory address
func (f *File) GetObjCProtoReferences() (map[uint64]*objc.Protocol, error) {
	protRefs := make(map[uint64]*objc.Protocol)

	for _, s := range f.Segments() {
		if strings.HasPrefix(s.Name, "__DATA") {
			for _, secName := range []string{"__objc_protorefs", "__objc_protolist"} { // External references to protocols and list of ObjC protocols
				if sec := f.Section(s.Name, secName); sec != nil {
					if err := f.cr.SeekToAddr(sec.Addr); err != nil {
						return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
					}

					dat := make([]byte, sec.Size)
					if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
						return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
					}

					protoPtrs := make([]uint64, sec.Size/f.pointerSize())
					if err := binary.Read(bytes.NewReader(dat), f.ByteOrder, &protoPtrs); err != nil {
						return nil, fmt.Errorf("failed to read %s.%s pointers: %v", sec.Seg, sec.Name, err)
					}

					for idx, ptr := range protoPtrs {
						proto, err := f.getObjcProtocol(f.vma.Convert(ptr))
						if err != nil {
							return nil, fmt.Errorf("failed to read protocol_t at ptr: %#x (converted %#x); %v", ptr, f.vma.Convert(ptr), err)
						}
						protRefs[sec.Addr+uint64(idx*sizeOfInt64)] = proto
					}
				}
			}
		}
	}

	return protRefs, nil
}

// GetObjCSelectorReferences returns a map of selector names to their section data virtual memory address
func (f *File) GetObjCSelectorReferences() (map[uint64]*objc.Selector, error) {
	selRefs := make(map[uint64]*objc.Selector)

	for _, s := range f.Segments() {
		if strings.HasPrefix(s.Name, "__DATA") {
			if sec := f.Section(s.Name, "__objc_selrefs"); sec != nil { // External references to selectors
				if err := f.cr.SeekToAddr(sec.Addr); err != nil {
					return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
				}

				dat := make([]byte, sec.Size)
				if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
					return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
				}

				selPtrs := make([]uint64, sec.Size/f.pointerSize())
				if err := binary.Read(bytes.NewReader(dat), f.ByteOrder, &selPtrs); err != nil {
					return nil, fmt.Errorf("failed to read %s.%s pointers: %v", sec.Seg, sec.Name, err)
				}

				for idx, sel := range selPtrs {
					sel = f.vma.Convert(sel)
					selName, err := f.GetCString(sel)
					if err != nil {
						return nil, fmt.Errorf("failed to read selector name cstring: %v", err)
					}
					selRefs[sec.Addr+uint64(idx*sizeOfInt64)] = &objc.Selector{
						VMAddr: sel,
						Name:   selName,
					}
				}
			}
		}
	}

	return selRefs, nil
}

// GetCFStrings returns the Objective-C CFStrings
func (f *File) GetCFStrings() ([]objc.CFString, error) {
	var err error
	var cfstrings []objc.CFString

	for _, s := range f.Segments() {
		if sec := f.Section(s.Name, "__cfstring"); sec != nil {
			if err := f.cr.SeekToAddr(sec.Addr); err != nil {
				return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
			}

			dat := make([]byte, sec.Size)
			if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
				return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
			}

			r := bytes.NewReader(dat)

			cfstrings = make([]objc.CFString, int(sec.Size)/binary.Size(objc.CFString64Type{}))
			for idx := range cfstrings {
				if err := binary.Read(r, f.ByteOrder, &cfstrings[idx].CFString64Type); err != nil {
					return nil, fmt.Errorf("failed to read %T structs: %v", cfstrings[idx].CFString64Type, err)
				}
			}

			for idx := range cfstrings {
				cfstrings[idx].IsaVMAddr = f.vma.Convert(cfstrings[idx].IsaVMAddr)
				if bind, err := f.GetBindName(cfstrings[idx].IsaVMAddr); err == nil {
					cfstrings[idx].ISA = bind
				}
				cfstrings[idx].Data = f.vma.Convert(cfstrings[idx].Data)
				if cfstrings[idx].Data == 0 {
					return nil, fmt.Errorf("unhandled cstring parse case where data is 0") // TODO: finish this
					// uint64_t n_value;
					// const char *symbol_name = get_symbol_64(offset + offsetof(struct cfstring64_t, characters), S, info, n_value);
					// if (symbol_name == nullptr)
					//   return nullptr;
					// cfs_characters = n_value;
				}
				cfstrings[idx].Name, err = f.GetCString(cfstrings[idx].Data)
				if err != nil {
					return nil, fmt.Errorf("failed to read cstring: %v", err)
				}
				if c, ok := f.objc[cfstrings[idx].IsaVMAddr]; ok {
					cfstrings[idx].Class = c.(*objc.Class)
				}
				cfstrings[idx].Address = sec.Addr + uint64(idx*binary.Size(objc.CFString64Type{}))
			}
		}
	}

	return cfstrings, nil
}

// GetObjCIntObj parses the __objc_intobj section and returns a map of
func (f *File) GetObjCIntegerObjects() (map[uint64]*objc.IntObj, error) {
	if sec := f.Section("__TEXT", "__objc_intobj"); sec != nil {
		if err := f.cr.SeekToAddr(sec.Addr); err != nil {
			return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
		}
		dat := make([]byte, sec.Size)
		if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
			return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
		}

		intObjs := make([]objc.IntObj, int(sec.Size)/binary.Size(objc.IntObj{}))
		if err := binary.Read(bytes.NewReader(dat), f.ByteOrder, &intObjs); err != nil {
			return nil, fmt.Errorf("failed to read %T structs: %v", intObjs, err)
		}

		intObjMap := make(map[uint64]*objc.IntObj)
		for idx, intObj := range intObjs {
			intObjMap[sec.Addr+uint64(idx*binary.Size(objc.IntObj{}))] = &intObj
		}

		return intObjMap, nil
	}

	return nil, fmt.Errorf("macho does not contain __objc_intobj section: %w", ErrObjcSectionNotFound)
}

// GetObjCStubs returns the Objective-C stubs
func (f *File) GetObjCStubs(parse func(uint64, []byte) (map[uint64]*objc.Stub, error)) (map[uint64]*objc.Stub, error) {
	if sec := f.Section("__TEXT", "__objc_stubs"); sec != nil {
		if err := f.cr.SeekToAddr(sec.Addr); err != nil {
			return nil, fmt.Errorf("failed to seek to %s addr %#x: %v", sec.Name, sec.Addr, err)
		}
		dat := make([]byte, sec.Size)
		if err := binary.Read(f.cr, f.ByteOrder, dat); err != nil {
			return nil, fmt.Errorf("failed to read %s.%s data: %v", sec.Seg, sec.Name, err)
		}
		return parse(sec.Addr, dat)
	}

	return nil, fmt.Errorf("macho does not contain __objc_stubs section: %w", ErrObjcSectionNotFound)
}