    const std = @import("std");
    const builtin = @import("builtin");
    const assert = std.debug.assert;
    const io = std.io;
    const mem = std.mem;
    const meta = std.meta;
    const testing = std.testing;

    const Allocator = mem.Allocator;

    pub const cpu_type_t = c_int;
    pub const cpu_subtype_t = c_int;
    pub const vm_prot_t = c_int;

    pub const mach_header = extern struct {
        magic: u32,
        cputype: cpu_type_t,
        cpusubtype: cpu_subtype_t,
        filetype: u32,
        ncmds: u32,
        sizeofcmds: u32,
        flags: u32,
    };

    pub const mach_header_64 = extern struct {
        magic: u32 = MH_MAGIC_64,
        cputype: cpu_type_t = 0,
        cpusubtype: cpu_subtype_t = 0,
        filetype: u32 = 0,
        ncmds: u32 = 0,
        sizeofcmds: u32 = 0,
        flags: u32 = 0,
        reserved: u32 = 0,
    };

    pub const fat_header = extern struct {
        magic: u32,
        nfat_arch: u32,
    };

    pub const fat_arch = extern struct {
        cputype: cpu_type_t,
        cpusubtype: cpu_subtype_t,
        offset: u32,
        size: u32,
        @"align": u32,
    };

    pub const load_command = extern struct {
        cmd: LC,
        cmdsize: u32,
    };

    /// The uuid load command contains a single 128-bit unique random number that
    /// identifies an object produced by the static link editor.
    pub const uuid_command = extern struct {
        /// LC_UUID
        cmd: LC = .UUID,

        /// sizeof(struct uuid_command)
        cmdsize: u32,

        /// the 128-bit uuid
        uuid: [16]u8,
    };

    /// The version_min_command contains the min OS version on which this
    /// binary was built to run.
    pub const version_min_command = extern struct {
        /// LC_VERSION_MIN_MACOSX or LC_VERSION_MIN_IPHONEOS or LC_VERSION_MIN_WATCHOS or LC_VERSION_MIN_TVOS
        cmd: LC,

        /// sizeof(struct version_min_command)
        cmdsize: u32,

        /// X.Y.Z is encoded in nibbles xxxx.yy.zz
        version: u32,

        /// X.Y.Z is encoded in nibbles xxxx.yy.zz
        sdk: u32,
    };

    /// The source_version_command is an optional load command containing
    /// the version of the sources used to build the binary.
    pub const source_version_command = extern struct {
        /// LC_SOURCE_VERSION
        cmd: LC = .SOURCE_VERSION,

        /// sizeof(source_version_command)
        cmdsize: u32,

        /// A.B.C.D.E packed as a24.b10.c10.d10.e10
        version: u64,
    };

    /// The build_version_command contains the min OS version on which this
    /// binary was built to run for its platform. The list of known platforms and
    /// tool values following it.
    pub const build_version_command = extern struct {
        /// LC_BUILD_VERSION
        cmd: LC = .BUILD_VERSION,

        /// sizeof(struct build_version_command) plus
        /// ntools * sizeof(struct build_version_command)
        cmdsize: u32,

        /// platform
        platform: PLATFORM,

        /// X.Y.Z is encoded in nibbles xxxx.yy.zz
        minos: u32,

        /// X.Y.Z is encoded in nibbles xxxx.yy.zz
        sdk: u32,

        /// number of tool entries following this
        ntools: u32,
    };

    pub const build_tool_version = extern struct {
        /// enum for the tool
        tool: TOOL,

        /// version number of the tool
        version: u32,
    };

    pub const PLATFORM = enum(u32) {
        MACOS = 0x1,
        IOS = 0x2,
        TVOS = 0x3,
        WATCHOS = 0x4,
        BRIDGEOS = 0x5,
        MACCATALYST = 0x6,
        IOSSIMULATOR = 0x7,
        TVOSSIMULATOR = 0x8,
        WATCHOSSIMULATOR = 0x9,
        DRIVERKIT = 0x10,
        _,
    };

    pub const TOOL = enum(u32) {
        CLANG = 0x1,
        SWIFT = 0x2,
        LD = 0x3,
        _,
    };

    /// The entry_point_command is a replacement for thread_command.
    /// It is used for main executables to specify the location (file offset)
    /// of main(). If -stack_size was used at link time, the stacksize
    /// field will contain the stack size needed for the main thread.
    pub const entry_point_command = extern struct {
        /// LC_MAIN only used in MH_EXECUTE filetypes
        cmd: LC = .MAIN,

        /// sizeof(struct entry_point_command)
        cmdsize: u32,

        /// file (__TEXT) offset of main()
        entryoff: u64,

        /// if not zero, initial stack size
        stacksize: u64,
    };

    /// The symtab_command contains the offsets and sizes of the link-edit 4.3BSD
    /// "stab" style symbol table information as described in the header files
    /// <nlist.h> and <stab.h>.
    pub const symtab_command = extern struct {
        /// LC_SYMTAB
        cmd: LC = .SYMTAB,

        /// sizeof(struct symtab_command)
        cmdsize: u32,

        /// symbol table offset
        symoff: u32,

        /// number of symbol table entries
        nsyms: u32,

        /// string table offset
        stroff: u32,

        /// string table size in bytes
        strsize: u32,
    };

    /// This is the second set of the symbolic information which is used to support
    /// the data structures for the dynamically link editor.
    ///
    /// The original set of symbolic information in the symtab_command which contains
    /// the symbol and string tables must also be present when this load command is
    /// present.  When this load command is present the symbol table is organized
    /// into three groups of symbols:
    ///  local symbols (static and debugging symbols) - grouped by module
    ///  defined external symbols - grouped by module (sorted by name if not lib)
    ///  undefined external symbols (sorted by name if MH_BINDATLOAD is not set,
    ///       			    and in order the were seen by the static
    ///  			    linker if MH_BINDATLOAD is set)
    /// In this load command there are offsets and counts to each of the three groups
    /// of symbols.
    ///
    /// This load command contains a the offsets and sizes of the following new
    /// symbolic information tables:
    ///  table of contents
    ///  module table
    ///  reference symbol table
    ///  indirect symbol table
    /// The first three tables above (the table of contents, module table and
    /// reference symbol table) are only present if the file is a dynamically linked
    /// shared library.  For executable and object modules, which are files
    /// containing only one module, the information that would be in these three
    /// tables is determined as follows:
    /// 	table of contents - the defined external symbols are sorted by name
    ///  module table - the file contains only one module so everything in the
    ///  	       file is part of the module.
    ///  reference symbol table - is the defined and undefined external symbols
    ///
    /// For dynamically linked shared library files this load command also contains
    /// offsets and sizes to the pool of relocation entries for all sections
    /// separated into two groups:
    ///  external relocation entries
    ///  local relocation entries
    /// For executable and object modules the relocation entries continue to hang
    /// off the section structures.
    pub const dysymtab_command = extern struct {
        /// LC_DYSYMTAB
        cmd: LC = .DYSYMTAB,

        /// sizeof(struct dysymtab_command)
        cmdsize: u32,

        // The symbols indicated by symoff and nsyms of the LC_SYMTAB load command

        // are grouped into the following three groups:

        //    local symbols (further grouped by the module they are from)

        //    defined external symbols (further grouped by the module they are from)

        //    undefined symbols

        //

        // The local symbols are used only for debugging.  The dynamic binding

        // process may have to use them to indicate to the debugger the local

        // symbols for a module that is being bound.

        //

        // The last two groups are used by the dynamic binding process to do the

        // binding (indirectly through the module table and the reference symbol

        // table when this is a dynamically linked shared library file).

        /// index of local symbols
        ilocalsym: u32,

        /// number of local symbols
        nlocalsym: u32,

        /// index to externally defined symbols
        iextdefsym: u32,

        /// number of externally defined symbols
        nextdefsym: u32,

        /// index to undefined symbols
        iundefsym: u32,

        /// number of undefined symbols
        nundefsym: u32,

        // For the for the dynamic binding process to find which module a symbol

        // is defined in the table of contents is used (analogous to the ranlib

        // structure in an archive) which maps defined external symbols to modules

        // they are defined in.  This exists only in a dynamically linked shared

        // library file.  For executable and object modules the defined external

        // symbols are sorted by name and is use as the table of contents.

        /// file offset to table of contents
        tocoff: u32,

        /// number of entries in table of contents
        ntoc: u32,

        // To support dynamic binding of "modules" (whole object files) the symbol

        // table must reflect the modules that the file was created from.  This is

        // done by having a module table that has indexes and counts into the merged

        // tables for each module.  The module structure that these two entries

        // refer to is described below.  This exists only in a dynamically linked

        // shared library file.  For executable and object modules the file only

        // contains one module so everything in the file belongs to the module.

        /// file offset to module table
        modtaboff: u32,

        /// number of module table entries
        nmodtab: u32,

        // To support dynamic module binding the module structure for each module

        // indicates the external references (defined and undefined) each module

        // makes.  For each module there is an offset and a count into the

        // reference symbol table for the symbols that the module references.

        // This exists only in a dynamically linked shared library file.  For

        // executable and object modules the defined external symbols and the

        // undefined external symbols indicates the external references.

        /// offset to referenced symbol table
        extrefsymoff: u32,

        /// number of referenced symbol table entries
        nextrefsyms: u32,

        // The sections that contain "symbol pointers" and "routine stubs" have

        // indexes and (implied counts based on the size of the section and fixed

        // size of the entry) into the "indirect symbol" table for each pointer

        // and stub.  For every section of these two types the index into the

        // indirect symbol table is stored in the section header in the field

        // reserved1.  An indirect symbol table entry is simply a 32bit index into

        // the symbol table to the symbol that the pointer or stub is referring to.

        // The indirect symbol table is ordered to match the entries in the section.

        /// file offset to the indirect symbol table
        indirectsymoff: u32,

        /// number of indirect symbol table entries
        nindirectsyms: u32,

        // To support relocating an individual module in a library file quickly the

        // external relocation entries for each module in the library need to be

        // accessed efficiently.  Since the relocation entries can't be accessed

        // through the section headers for a library file they are separated into

        // groups of local and external entries further grouped by module.  In this

        // case the presents of this load command who's extreloff, nextrel,

        // locreloff and nlocrel fields are non-zero indicates that the relocation

        // entries of non-merged sections are not referenced through the section

        // structures (and the reloff and nreloc fields in the section headers are

        // set to zero).

        //

        // Since the relocation entries are not accessed through the section headers

        // this requires the r_address field to be something other than a section

        // offset to identify the item to be relocated.  In this case r_address is

        // set to the offset from the vmaddr of the first LC_SEGMENT command.

        // For MH_SPLIT_SEGS images r_address is set to the the offset from the

        // vmaddr of the first read-write LC_SEGMENT command.

        //

        // The relocation entries are grouped by module and the module table

        // entries have indexes and counts into them for the group of external

        // relocation entries for that the module.

        //

        // For sections that are merged across modules there must not be any

        // remaining external relocation entries for them (for merged sections

        // remaining relocation entries must be local).

        /// offset to external relocation entries
        extreloff: u32,

        /// number of external relocation entries
        nextrel: u32,

        // All the local relocation entries are grouped together (they are not

        // grouped by their module since they are only used if the object is moved

        // from it staticly link edited address).

        /// offset to local relocation entries
        locreloff: u32,

        /// number of local relocation entries
        nlocrel: u32,
    };

    /// The linkedit_data_command contains the offsets and sizes of a blob
    /// of data in the __LINKEDIT segment.
    pub const linkedit_data_command = extern struct {
        /// LC_CODE_SIGNATURE, LC_SEGMENT_SPLIT_INFO, LC_FUNCTION_STARTS, LC_DATA_IN_CODE, LC_DYLIB_CODE_SIGN_DRS or LC_LINKER_OPTIMIZATION_HINT.
        cmd: LC,

        /// sizeof(struct linkedit_data_command)
        cmdsize: u32,

        /// file offset of data in __LINKEDIT segment
        dataoff: u32,

        /// file size of data in __LINKEDIT segment
        datasize: u32,
    };

    /// The dyld_info_command contains the file offsets and sizes of
    /// the new compressed form of the information dyld needs to
    /// load the image.  This information is used by dyld on Mac OS X
    /// 10.6 and later.  All information pointed to by this command
    /// is encoded using byte streams, so no endian swapping is needed
    /// to interpret it.
    pub const dyld_info_command = extern struct {
        /// LC_DYLD_INFO or LC_DYLD_INFO_ONLY
        cmd: LC,

        /// sizeof(struct dyld_info_command)
        cmdsize: u32,

        // Dyld rebases an image whenever dyld loads it at an address different

        // from its preferred address.  The rebase information is a stream

        // of byte sized opcodes whose symbolic names start with REBASE_OPCODE_.

        // Conceptually the rebase information is a table of tuples:

        //    <seg-index, seg-offset, type>

        // The opcodes are a compressed way to encode the table by only

        // encoding when a column changes.  In addition simple patterns

        // like "every n'th offset for m times" can be encoded in a few

        // bytes.

        /// file offset to rebase info
        rebase_off: u32,

        /// size of rebase info
        rebase_size: u32,

        // Dyld binds an image during the loading process, if the image

        // requires any pointers to be initialized to symbols in other images.

        // The bind information is a stream of byte sized

        // opcodes whose symbolic names start with BIND_OPCODE_.

        // Conceptually the bind information is a table of tuples:

        //    <seg-index, seg-offset, type, symbol-library-ordinal, symbol-name, addend>

        // The opcodes are a compressed way to encode the table by only

        // encoding when a column changes.  In addition simple patterns

        // like for runs of pointers initialzed to the same value can be

        // encoded in a few bytes.

        /// file offset to binding info
        bind_off: u32,

        /// size of binding info
        bind_size: u32,

        // Some C++ programs require dyld to unique symbols so that all

        // images in the process use the same copy of some code/data.

        // This step is done after binding. The content of the weak_bind

        // info is an opcode stream like the bind_info.  But it is sorted

        // alphabetically by symbol name.  This enable dyld to walk

        // all images with weak binding information in order and look

        // for collisions.  If there are no collisions, dyld does

        // no updating.  That means that some fixups are also encoded

        // in the bind_info.  For instance, all calls to "operator new"

        // are first bound to libstdc++.dylib using the information

        // in bind_info.  Then if some image overrides operator new

        // that is detected when the weak_bind information is processed

        // and the call to operator new is then rebound.

        /// file offset to weak binding info
        weak_bind_off: u32,

        /// size of weak binding info
        weak_bind_size: u32,

        // Some uses of external symbols do not need to be bound immediately.

        // Instead they can be lazily bound on first use.  The lazy_bind

        // are contains a stream of BIND opcodes to bind all lazy symbols.

        // Normal use is that dyld ignores the lazy_bind section when

        // loading an image.  Instead the static linker arranged for the

        // lazy pointer to initially point to a helper function which

        // pushes the offset into the lazy_bind area for the symbol

        // needing to be bound, then jumps to dyld which simply adds

        // the offset to lazy_bind_off to get the information on what

        // to bind.

        /// file offset to lazy binding info
        lazy_bind_off: u32,

        /// size of lazy binding info
        lazy_bind_size: u32,

        // The symbols exported by a dylib are encoded in a trie.  This

        // is a compact representation that factors out common prefixes.

        // It also reduces LINKEDIT pages in RAM because it encodes all

        // information (name, address, flags) in one small, contiguous range.

        // The export area is a stream of nodes.  The first node sequentially

        // is the start node for the trie.

        //

        // Nodes for a symbol start with a uleb128 that is the length of

        // the exported symbol information for the string so far.

        // If there is no exported symbol, the node starts with a zero byte.

        // If there is exported info, it follows the length.

        //

        // First is a uleb128 containing flags. Normally, it is followed by

        // a uleb128 encoded offset which is location of the content named

        // by the symbol from the mach_header for the image.  If the flags

        // is EXPORT_SYMBOL_FLAGS_REEXPORT, then following the flags is

        // a uleb128 encoded library ordinal, then a zero terminated

        // UTF8 string.  If the string is zero length, then the symbol

        // is re-export from the specified dylib with the same name.

        // If the flags is EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER, then following

        // the flags is two uleb128s: the stub offset and the resolver offset.

        // The stub is used by non-lazy pointers.  The resolver is used

        // by lazy pointers and must be called to get the actual address to use.

        //

        // After the optional exported symbol information is a byte of

        // how many edges (0-255) that this node has leaving it,

        // followed by each edge.

        // Each edge is a zero terminated UTF8 of the addition chars

        // in the symbol, followed by a uleb128 offset for the node that

        // edge points to.

        /// file offset to lazy binding info
        export_off: u32,

        /// size of lazy binding info
        export_size: u32,
    };

    /// A program that uses a dynamic linker contains a dylinker_command to identify
    /// the name of the dynamic linker (LC_LOAD_DYLINKER). And a dynamic linker
    /// contains a dylinker_command to identify the dynamic linker (LC_ID_DYLINKER).
    /// A file can have at most one of these.
    /// This struct is also used for the LC_DYLD_ENVIRONMENT load command and contains
    /// string for dyld to treat like an environment variable.
    pub const dylinker_command = extern struct {
        /// LC_ID_DYLINKER, LC_LOAD_DYLINKER, or LC_DYLD_ENVIRONMENT
        cmd: LC,

        /// includes pathname string
        cmdsize: u32,

        /// A variable length string in a load command is represented by an lc_str
        /// union.  The strings are stored just after the load command structure and
        /// the offset is from the start of the load command structure.  The size
        /// of the string is reflected in the cmdsize field of the load command.
        /// Once again any padded bytes to bring the cmdsize field to a multiple
        /// of 4 bytes must be zero.
        name: u32,
    };

    /// A dynamically linked shared library (filetype == MH_DYLIB in the mach header)
    /// contains a dylib_command (cmd == LC_ID_DYLIB) to identify the library.
    /// An object that uses a dynamically linked shared library also contains a
    /// dylib_command (cmd == LC_LOAD_DYLIB, LC_LOAD_WEAK_DYLIB, or
    /// LC_REEXPORT_DYLIB) for each library it uses.
    pub const dylib_command = extern struct {
        /// LC_ID_DYLIB, LC_LOAD_WEAK_DYLIB, LC_LOAD_DYLIB, LC_REEXPORT_DYLIB
        cmd: LC,

        /// includes pathname string
        cmdsize: u32,

        /// the library identification
        dylib: dylib,
    };

    /// Dynamicaly linked shared libraries are identified by two things.  The
    /// pathname (the name of the library as found for execution), and the
    /// compatibility version number.  The pathname must match and the compatibility
    /// number in the user of the library must be greater than or equal to the
    /// library being used.  The time stamp is used to record the time a library was
    /// built and copied into user so it can be use to determined if the library used
    /// at runtime is exactly the same as used to built the program.
    pub const dylib = extern struct {
        /// library's pathname (offset pointing at the end of dylib_command)
        name: u32,

        /// library's build timestamp
        timestamp: u32,

        /// library's current version number
        current_version: u32,

        /// library's compatibility version number
        compatibility_version: u32,
    };

    /// The rpath_command contains a path which at runtime should be added to the current
    /// run path used to find @rpath prefixed dylibs.
    pub const rpath_command = extern struct {
        /// LC_RPATH
        cmd: LC = .RPATH,

        /// includes string
        cmdsize: u32,

        /// path to add to run path
        path: u32,
    };

    /// The segment load command indicates that a part of this file is to be
    /// mapped into the task's address space.  The size of this segment in memory,
    /// vmsize, maybe equal to or larger than the amount to map from this file,
    /// filesize.  The file is mapped starting at fileoff to the beginning of
    /// the segment in memory, vmaddr.  The rest of the memory of the segment,
    /// if any, is allocated zero fill on demand.  The segment's maximum virtual
    /// memory protection and initial virtual memory protection are specified
    /// by the maxprot and initprot fields.  If the segment has sections then the
    /// section structures directly follow the segment command and their size is
    /// reflected in cmdsize.
    pub const segment_command = extern struct {
        /// LC_SEGMENT
        cmd: LC = .SEGMENT,

        /// includes sizeof section structs
        cmdsize: u32,

        /// segment name
        segname: [16]u8,

        /// memory address of this segment
        vmaddr: u32,

        /// memory size of this segment
        vmsize: u32,

        /// file offset of this segment
        fileoff: u32,

        /// amount to map from the file
        filesize: u32,

        /// maximum VM protection
        maxprot: vm_prot_t,

        /// initial VM protection
        initprot: vm_prot_t,

        /// number of sections in segment
        nsects: u32,
        flags: u32,
    };

    /// The 64-bit segment load command indicates that a part of this file is to be
    /// mapped into a 64-bit task's address space.  If the 64-bit segment has
    /// sections then section_64 structures directly follow the 64-bit segment
    /// command and their size is reflected in cmdsize.
    pub const segment_command_64 = extern struct {
        /// LC_SEGMENT_64
        cmd: LC = .SEGMENT_64,

        /// includes sizeof section_64 structs
        cmdsize: u32,
        // TODO lazy values in stage2

        // cmdsize: u32 = @sizeOf(segment_command_64),

        /// segment name
        segname: [16]u8,

        /// memory address of this segment
        vmaddr: u64 = 0,

        /// memory size of this segment
        vmsize: u64 = 0,

        /// file offset of this segment
        fileoff: u64 = 0,

        /// amount to map from the file
        filesize: u64 = 0,

        /// maximum VM protection
        maxprot: vm_prot_t = PROT.NONE,

        /// initial VM protection
        initprot: vm_prot_t = PROT.NONE,

        /// number of sections in segment
        nsects: u32 = 0,
        flags: u32 = 0,

        pub fn segName(seg: *const segment_command_64) []const u8 {
            return parseName(&seg.segname);
        }
    };

    pub const PROT = struct {
        /// [MC2] no permissions
        pub const NONE: vm_prot_t = 0x00;
        /// [MC2] pages can be read
        pub const READ: vm_prot_t = 0x01;
        /// [MC2] pages can be written
        pub const WRITE: vm_prot_t = 0x02;
        /// [MC2] pages can be executed
        pub const EXEC: vm_prot_t = 0x04;
        /// When a caller finds that they cannot obtain write permission on a
        /// mapped entry, the following flag can be used. The entry will be
        /// made "needs copy" effectively copying the object (using COW),
        /// and write permission will be added to the maximum protections for
        /// the associated entry.
        pub const COPY: vm_prot_t = 0x10;
    };

    /// A segment is made up of zero or more sections.  Non-MH_OBJECT files have
    /// all of their segments with the proper sections in each, and padded to the
    /// specified segment alignment when produced by the link editor.  The first
    /// segment of a MH_EXECUTE and MH_FVMLIB format file contains the mach_header
    /// and load commands of the object file before its first section.  The zero
    /// fill sections are always last in their segment (in all formats).  This
    /// allows the zeroed segment padding to be mapped into memory where zero fill
    /// sections might be. The gigabyte zero fill sections, those with the section
    /// type S_GB_ZEROFILL, can only be in a segment with sections of this type.
    /// These segments are then placed after all other segments.
    ///
    /// The MH_OBJECT format has all of its sections in one segment for
    /// compactness.  There is no padding to a specified segment boundary and the
    /// mach_header and load commands are not part of the segment.
    ///
    /// Sections with the same section name, sectname, going into the same segment,
    /// segname, are combined by the link editor.  The resulting section is aligned
    /// to the maximum alignment of the combined sections and is the new section's
    /// alignment.  The combined sections are aligned to their original alignment in
    /// the combined section.  Any padded bytes to get the specified alignment are
    /// zeroed.
    ///
    /// The format of the relocation entries referenced by the reloff and nreloc
    /// fields of the section structure for mach object files is described in the
    /// header file <reloc.h>.
    pub const @"section" = extern struct {
        /// name of this section
        sectname: [16]u8,

        /// segment this section goes in
        segname: [16]u8,

        /// memory address of this section
        addr: u32,

        /// size in bytes of this section
        size: u32,

        /// file offset of this section
        offset: u32,

        /// section alignment (power of 2)
        @"align": u32,

        /// file offset of relocation entries
        reloff: u32,

        /// number of relocation entries
        nreloc: u32,

        /// flags (section type and attributes
        flags: u32,

        /// reserved (for offset or index)
        reserved1: u32,

        /// reserved (for count or sizeof)
        reserved2: u32,
    };

    pub const section_64 = extern struct {
        /// name of this section
        sectname: [16]u8,

        /// segment this section goes in
        segname: [16]u8,

        /// memory address of this section
        addr: u64 = 0,

        /// size in bytes of this section
        size: u64 = 0,

        /// file offset of this section
        offset: u32 = 0,

        /// section alignment (power of 2)
        @"align": u32 = 0,

        /// file offset of relocation entries
        reloff: u32 = 0,

        /// number of relocation entries
        nreloc: u32 = 0,

        /// flags (section type and attributes
        flags: u32 = S_REGULAR,

        /// reserved (for offset or index)
        reserved1: u32 = 0,

        /// reserved (for count or sizeof)
        reserved2: u32 = 0,

        /// reserved
        reserved3: u32 = 0,

        pub fn sectName(sect: *const section_64) []const u8 {
            return parseName(&sect.sectname);
        }

        pub fn segName(sect: *const section_64) []const u8 {
            return parseName(&sect.segname);
        }

        pub fn @"type"(sect: section_64) u8 {
            return @truncate(u8, sect.flags & 0xff);
        }

        pub fn attrs(sect: section_64) u32 {
            return sect.flags & 0xffffff00;
        }

        pub fn isCode(sect: section_64) bool {
            const attr = sect.attrs();
            return attr & S_ATTR_PURE_INSTRUCTIONS != 0 or attr & S_ATTR_SOME_INSTRUCTIONS != 0;
        }

        pub fn isZerofill(sect: section_64) bool {
            const tt = sect.@"type"();
            return tt == S_ZEROFILL or tt == S_GB_ZEROFILL or tt == S_THREAD_LOCAL_ZEROFILL;
        }

        pub fn isSymbolStubs(sect: section_64) bool {
            const tt = sect.@"type"();
            return tt == S_SYMBOL_STUBS;
        }

        pub fn isDebug(sect: section_64) bool {
            return sect.attrs() & S_ATTR_DEBUG != 0;
        }

        pub fn isDontDeadStrip(sect: section_64) bool {
            return sect.attrs() & S_ATTR_NO_DEAD_STRIP != 0;
        }

        pub fn isDontDeadStripIfReferencesLive(sect: section_64) bool {
            return sect.attrs() & S_ATTR_LIVE_SUPPORT != 0;
        }
    };

    fn parseName(name: *const [16]u8) []const u8 {
        const len = mem.indexOfScalar(u8, name, @as(u8, 0)) orelse name.len;
        return name[0..len];
    }

    pub const nlist = extern struct {
        n_strx: u32,
        n_type: u8,
        n_sect: u8,
        n_desc: i16,
        n_value: u32,
    };

    pub const nlist_64 = extern struct {
        n_strx: u32,
        n_type: u8,
        n_sect: u8,
        n_desc: u16,
        n_value: u64,

        pub fn stab(sym: nlist_64) bool {
            return (N_STAB & sym.n_type) != 0;
        }

        pub fn pext(sym: nlist_64) bool {
            return (N_PEXT & sym.n_type) != 0;
        }

        pub fn ext(sym: nlist_64) bool {
            return (N_EXT & sym.n_type) != 0;
        }

        pub fn sect(sym: nlist_64) bool {
            const type_ = N_TYPE & sym.n_type;
            return type_ == N_SECT;
        }

        pub fn undf(sym: nlist_64) bool {
            const type_ = N_TYPE & sym.n_type;
            return type_ == N_UNDF;
        }

        pub fn indr(sym: nlist_64) bool {
            const type_ = N_TYPE & sym.n_type;
            return type_ == N_INDR;
        }

        pub fn abs(sym: nlist_64) bool {
            const type_ = N_TYPE & sym.n_type;
            return type_ == N_ABS;
        }

        pub fn weakDef(sym: nlist_64) bool {
            return (sym.n_desc & N_WEAK_DEF) != 0;
        }

        pub fn weakRef(sym: nlist_64) bool {
            return (sym.n_desc & N_WEAK_REF) != 0;
        }

        pub fn discarded(sym: nlist_64) bool {
            return (sym.n_desc & N_DESC_DISCARDED) != 0;
        }

        pub fn tentative(sym: nlist_64) bool {
            if (!sym.undf()) return false;
            return sym.n_value != 0;
        }
    };

    /// Format of a relocation entry of a Mach-O file.  Modified from the 4.3BSD
    /// format.  The modifications from the original format were changing the value
    /// of the r_symbolnum field for "local" (r_extern == 0) relocation entries.
    /// This modification is required to support symbols in an arbitrary number of
    /// sections not just the three sections (text, data and bss) in a 4.3BSD file.
    /// Also the last 4 bits have had the r_type tag added to them.
    pub const relocation_info = packed struct {
        /// offset in the section to what is being relocated
        r_address: i32,

        /// symbol index if r_extern == 1 or section ordinal if r_extern == 0
        r_symbolnum: u24,

        /// was relocated pc relative already
        r_pcrel: u1,

        /// 0=byte, 1=word, 2=long, 3=quad
        r_length: u2,

        /// does not include value of sym referenced
        r_extern: u1,

        /// if not 0, machine specific relocation type
        r_type: u4,
    };

    /// After MacOS X 10.1 when a new load command is added that is required to be
    /// understood by the dynamic linker for the image to execute properly the
    /// LC_REQ_DYLD bit will be or'ed into the load command constant.  If the dynamic
    /// linker sees such a load command it it does not understand will issue a
    /// "unknown load command required for execution" error and refuse to use the
    /// image.  Other load commands without this bit that are not understood will
    /// simply be ignored.
    pub const LC_REQ_DYLD = 0x80000000;

    pub const LC = enum(u32) {
        /// No load command - invalid
        NONE = 0x0,

        /// segment of this file to be mapped
        SEGMENT = 0x1,

        /// link-edit stab symbol table info
        SYMTAB = 0x2,

        /// link-edit gdb symbol table info (obsolete)
        SYMSEG = 0x3,

        /// thread
        THREAD = 0x4,

        /// unix thread (includes a stack)
        UNIXTHREAD = 0x5,

        /// load a specified fixed VM shared library
        LOADFVMLIB = 0x6,

        /// fixed VM shared library identification
        IDFVMLIB = 0x7,

        /// object identification info (obsolete)
        IDENT = 0x8,

        /// fixed VM file inclusion (internal use)
        FVMFILE = 0x9,

        /// prepage command (internal use)
        PREPAGE = 0xa,

        /// dynamic link-edit symbol table info
        DYSYMTAB = 0xb,

        /// load a dynamically linked shared library
        LOAD_DYLIB = 0xc,

        /// dynamically linked shared lib ident
        ID_DYLIB = 0xd,

        /// load a dynamic linker
        LOAD_DYLINKER = 0xe,

        /// dynamic linker identification
        ID_DYLINKER = 0xf,

        /// modules prebound for a dynamically
        PREBOUND_DYLIB = 0x10,

        /// image routines
        ROUTINES = 0x11,

        /// sub framework
        SUB_FRAMEWORK = 0x12,

        /// sub umbrella
        SUB_UMBRELLA = 0x13,

        /// sub client
        SUB_CLIENT = 0x14,

        /// sub library
        SUB_LIBRARY = 0x15,

        /// two-level namespace lookup hints
        TWOLEVEL_HINTS = 0x16,

        /// prebind checksum
        PREBIND_CKSUM = 0x17,

        /// load a dynamically linked shared library that is allowed to be missing
        /// (all symbols are weak imported).
        LOAD_WEAK_DYLIB = (0x18 | LC_REQ_DYLD),

        /// 64-bit segment of this file to be mapped
        SEGMENT_64 = 0x19,

        /// 64-bit image routines
        ROUTINES_64 = 0x1a,

        /// the uuid
        UUID = 0x1b,

        /// runpath additions
        RPATH = (0x1c | LC_REQ_DYLD),

        /// local of code signature
        CODE_SIGNATURE = 0x1d,

        /// local of info to split segments
        SEGMENT_SPLIT_INFO = 0x1e,

        /// load and re-export dylib
        REEXPORT_DYLIB = (0x1f | LC_REQ_DYLD),

        /// delay load of dylib until first use
        LAZY_LOAD_DYLIB = 0x20,

        /// encrypted segment information
        ENCRYPTION_INFO = 0x21,

        /// compressed dyld information
        DYLD_INFO = 0x22,

        /// compressed dyld information only
        DYLD_INFO_ONLY = (0x22 | LC_REQ_DYLD),

        /// load upward dylib
        LOAD_UPWARD_DYLIB = (0x23 | LC_REQ_DYLD),

        /// build for MacOSX min OS version
        VERSION_MIN_MACOSX = 0x24,

        /// build for iPhoneOS min OS version
        VERSION_MIN_IPHONEOS = 0x25,

        /// compressed table of function start addresses
        FUNCTION_STARTS = 0x26,

        /// string for dyld to treat like environment variable
        DYLD_ENVIRONMENT = 0x27,

        /// replacement for LC_UNIXTHREAD
        MAIN = (0x28 | LC_REQ_DYLD),

        /// table of non-instructions in __text
        DATA_IN_CODE = 0x29,

        /// source version used to build binary
        SOURCE_VERSION = 0x2A,

        /// Code signing DRs copied from linked dylibs
        DYLIB_CODE_SIGN_DRS = 0x2B,

        /// 64-bit encrypted segment information
        ENCRYPTION_INFO_64 = 0x2C,

        /// linker options in MH_OBJECT files
        LINKER_OPTION = 0x2D,

        /// optimization hints in MH_OBJECT files
        LINKER_OPTIMIZATION_HINT = 0x2E,

        /// build for AppleTV min OS version
        VERSION_MIN_TVOS = 0x2F,

        /// build for Watch min OS version
        VERSION_MIN_WATCHOS = 0x30,

        /// arbitrary data included within a Mach-O file
        NOTE = 0x31,

        /// build for platform min OS version
        BUILD_VERSION = 0x32,

        _,
    };

    /// the mach magic number
    pub const MH_MAGIC = 0xfeedface;

    /// NXSwapInt(MH_MAGIC)
    pub const MH_CIGAM = 0xcefaedfe;

    /// the 64-bit mach magic number
    pub const MH_MAGIC_64 = 0xfeedfacf;

    /// NXSwapInt(MH_MAGIC_64)
    pub const MH_CIGAM_64 = 0xcffaedfe;

    /// relocatable object file
    pub const MH_OBJECT = 0x1;

    /// demand paged executable file
    pub const MH_EXECUTE = 0x2;

    /// fixed VM shared library file
    pub const MH_FVMLIB = 0x3;

    /// core file
    pub const MH_CORE = 0x4;

    /// preloaded executable file
    pub const MH_PRELOAD = 0x5;

    /// dynamically bound shared library
    pub const MH_DYLIB = 0x6;

    /// dynamic link editor
    pub const MH_DYLINKER = 0x7;

    /// dynamically bound bundle file
    pub const MH_BUNDLE = 0x8;

    /// shared library stub for static linking only, no section contents
    pub const MH_DYLIB_STUB = 0x9;

    /// companion file with only debug sections
    pub const MH_DSYM = 0xa;

    /// x86_64 kexts
    pub const MH_KEXT_BUNDLE = 0xb;

    // Constants for the flags field of the mach_header

    /// the object file has no undefined references
    pub const MH_NOUNDEFS = 0x1;

    /// the object file is the output of an incremental link against a base file and can't be link edited again
    pub const MH_INCRLINK = 0x2;

    /// the object file is input for the dynamic linker and can't be staticly link edited again
    pub const MH_DYLDLINK = 0x4;

    /// the object file's undefined references are bound by the dynamic linker when loaded.
    pub const MH_BINDATLOAD = 0x8;

    /// the file has its dynamic undefined references prebound.
    pub const MH_PREBOUND = 0x10;

    /// the file has its read-only and read-write segments split
    pub const MH_SPLIT_SEGS = 0x20;

    /// the shared library init routine is to be run lazily via catching memory faults to its writeable segments (obsolete)
    pub const MH_LAZY_INIT = 0x40;

    /// the image is using two-level name space bindings
    pub const MH_TWOLEVEL = 0x80;

    /// the executable is forcing all images to use flat name space bindings
    pub const MH_FORCE_FLAT = 0x100;

    /// this umbrella guarantees no multiple defintions of symbols in its sub-images so the two-level namespace hints can always be used.
    pub const MH_NOMULTIDEFS = 0x200;

    /// do not have dyld notify the prebinding agent about this executable
    pub const MH_NOFIXPREBINDING = 0x400;

    /// the binary is not prebound but can have its prebinding redone. only used when MH_PREBOUND is not set.
    pub const MH_PREBINDABLE = 0x800;

    /// indicates that this binary binds to all two-level namespace modules of its dependent libraries. only used when MH_PREBINDABLE and MH_TWOLEVEL are both set.
    pub const MH_ALLMODSBOUND = 0x1000;

    /// safe to divide up the sections into sub-sections via symbols for dead code stripping
    pub const MH_SUBSECTIONS_VIA_SYMBOLS = 0x2000;

    /// the binary has been canonicalized via the unprebind operation
    pub const MH_CANONICAL = 0x4000;

    /// the final linked image contains external weak symbols
    pub const MH_WEAK_DEFINES = 0x8000;

    /// the final linked image uses weak symbols
    pub const MH_BINDS_TO_WEAK = 0x10000;

    /// When this bit is set, all stacks in the task will be given stack execution privilege.  Only used in MH_EXECUTE filetypes.
    pub const MH_ALLOW_STACK_EXECUTION = 0x20000;

    /// When this bit is set, the binary declares it is safe for use in processes with uid zero
    pub const MH_ROOT_SAFE = 0x40000;

    /// When this bit is set, the binary declares it is safe for use in processes when issetugid() is true
    pub const MH_SETUID_SAFE = 0x80000;

    /// When this bit is set on a dylib, the static linker does not need to examine dependent dylibs to see if any are re-exported
    pub const MH_NO_REEXPORTED_DYLIBS = 0x100000;

    /// When this bit is set, the OS will load the main executable at a random address.  Only used in MH_EXECUTE filetypes.
    pub const MH_PIE = 0x200000;

    /// Only for use on dylibs.  When linking against a dylib that has this bit set, the static linker will automatically not create a LC_LOAD_DYLIB load command to the dylib if no symbols are being referenced from the dylib.
    pub const MH_DEAD_STRIPPABLE_DYLIB = 0x400000;

    /// Contains a section of type S_THREAD_LOCAL_VARIABLES
    pub const MH_HAS_TLV_DESCRIPTORS = 0x800000;

    /// When this bit is set, the OS will run the main executable with a non-executable heap even on platforms (e.g. i386) that don't require it. Only used in MH_EXECUTE filetypes.
    pub const MH_NO_HEAP_EXECUTION = 0x1000000;

    /// The code was linked for use in an application extension.
    pub const MH_APP_EXTENSION_SAFE = 0x02000000;

    /// The external symbols listed in the nlist symbol table do not include all the symbols listed in the dyld info.
    pub const MH_NLIST_OUTOFSYNC_WITH_DYLDINFO = 0x04000000;

    // Constants for the flags field of the fat_header

    /// the fat magic number
    pub const FAT_MAGIC = 0xcafebabe;

    /// NXSwapLong(FAT_MAGIC)
    pub const FAT_CIGAM = 0xbebafeca;

    /// the 64-bit fat magic number
    pub const FAT_MAGIC_64 = 0xcafebabf;

    /// NXSwapLong(FAT_MAGIC_64)
    pub const FAT_CIGAM_64 = 0xbfbafeca;

    /// The flags field of a section structure is separated into two parts a section
    /// type and section attributes.  The section types are mutually exclusive (it
    /// can only have one type) but the section attributes are not (it may have more
    /// than one attribute).
    /// 256 section types
    pub const SECTION_TYPE = 0x000000ff;

    ///  24 section attributes
    pub const SECTION_ATTRIBUTES = 0xffffff00;

    /// regular section
    pub const S_REGULAR = 0x0;

    /// zero fill on demand section
    pub const S_ZEROFILL = 0x1;

    /// section with only literal C string
    pub const S_CSTRING_LITERALS = 0x2;

    /// section with only 4 byte literals
    pub const S_4BYTE_LITERALS = 0x3;

    /// section with only 8 byte literals
    pub const S_8BYTE_LITERALS = 0x4;

    /// section with only pointers to
    pub const S_LITERAL_POINTERS = 0x5;

    /// if any of these bits set, a symbolic debugging entry
    pub const N_STAB = 0xe0;

    /// private external symbol bit
    pub const N_PEXT = 0x10;

    /// mask for the type bits
    pub const N_TYPE = 0x0e;

    /// external symbol bit, set for external symbols
    pub const N_EXT = 0x01;

    /// symbol is undefined
    pub const N_UNDF = 0x0;

    /// symbol is absolute
    pub const N_ABS = 0x2;

    /// symbol is defined in the section number given in n_sect
    pub const N_SECT = 0xe;

    /// symbol is undefined  and the image is using a prebound
    /// value  for the symbol
    pub const N_PBUD = 0xc;

    /// symbol is defined to be the same as another symbol; the n_value
    /// field is an index into the string table specifying the name of the
    /// other symbol
    pub const N_INDR = 0xa;

    /// global symbol: name,,NO_SECT,type,0
    pub const N_GSYM = 0x20;

    /// procedure name (f77 kludge): name,,NO_SECT,0,0
    pub const N_FNAME = 0x22;

    /// procedure: name,,n_sect,linenumber,address
    pub const N_FUN = 0x24;

    /// static symbol: name,,n_sect,type,address
    pub const N_STSYM = 0x26;

    /// .lcomm symbol: name,,n_sect,type,address
    pub const N_LCSYM = 0x28;

    /// begin nsect sym: 0,,n_sect,0,address
    pub const N_BNSYM = 0x2e;

    /// AST file path: name,,NO_SECT,0,0
    pub const N_AST = 0x32;

    /// emitted with gcc2_compiled and in gcc source
    pub const N_OPT = 0x3c;

    /// register sym: name,,NO_SECT,type,register
    pub const N_RSYM = 0x40;

    /// src line: 0,,n_sect,linenumber,address
    pub const N_SLINE = 0x44;

    /// end nsect sym: 0,,n_sect,0,address
    pub const N_ENSYM = 0x4e;

    /// structure elt: name,,NO_SECT,type,struct_offset
    pub const N_SSYM = 0x60;

    /// source file name: name,,n_sect,0,address
    pub const N_SO = 0x64;

    /// object file name: name,,0,0,st_mtime
    pub const N_OSO = 0x66;

    /// local sym: name,,NO_SECT,type,offset
    pub const N_LSYM = 0x80;

    /// include file beginning: name,,NO_SECT,0,sum
    pub const N_BINCL = 0x82;

    /// #included file name: name,,n_sect,0,address
    pub const N_SOL = 0x84;

    /// compiler parameters: name,,NO_SECT,0,0
    pub const N_PARAMS = 0x86;

    /// compiler version: name,,NO_SECT,0,0
    pub const N_VERSION = 0x88;

    /// compiler -O level: name,,NO_SECT,0,0
    pub const N_OLEVEL = 0x8A;

    /// parameter: name,,NO_SECT,type,offset
    pub const N_PSYM = 0xa0;

    /// include file end: name,,NO_SECT,0,0
    pub const N_EINCL = 0xa2;

    /// alternate entry: name,,n_sect,linenumber,address
    pub const N_ENTRY = 0xa4;

    /// left bracket: 0,,NO_SECT,nesting level,address
    pub const N_LBRAC = 0xc0;

    /// deleted include file: name,,NO_SECT,0,sum
    pub const N_EXCL = 0xc2;

    /// right bracket: 0,,NO_SECT,nesting level,address
    pub const N_RBRAC = 0xe0;

    /// begin common: name,,NO_SECT,0,0
    pub const N_BCOMM = 0xe2;

    /// end common: name,,n_sect,0,0
    pub const N_ECOMM = 0xe4;

    /// end common (local name): 0,,n_sect,0,address
    pub const N_ECOML = 0xe8;

    /// second stab entry with length information
    pub const N_LENG = 0xfe;

    // For the two types of symbol pointers sections and the symbol stubs section

    // they have indirect symbol table entries.  For each of the entries in the

    // section the indirect symbol table entries, in corresponding order in the

    // indirect symbol table, start at the index stored in the reserved1 field

    // of the section structure.  Since the indirect symbol table entries

    // correspond to the entries in the section the number of indirect symbol table

    // entries is inferred from the size of the section divided by the size of the

    // entries in the section.  For symbol pointers sections the size of the entries

    // in the section is 4 bytes and for symbol stubs sections the byte size of the

    // stubs is stored in the reserved2 field of the section structure.

    /// section with only non-lazy symbol pointers
    pub const S_NON_LAZY_SYMBOL_POINTERS = 0x6;

    /// section with only lazy symbol pointers
    pub const S_LAZY_SYMBOL_POINTERS = 0x7;

    /// section with only symbol stubs, byte size of stub in the reserved2 field
    pub const S_SYMBOL_STUBS = 0x8;

    /// section with only function pointers for initialization
    pub const S_MOD_INIT_FUNC_POINTERS = 0x9;

    /// section with only function pointers for termination
    pub const S_MOD_TERM_FUNC_POINTERS = 0xa;

    /// section contains symbols that are to be coalesced
    pub const S_COALESCED = 0xb;

    /// zero fill on demand section (that can be larger than 4 gigabytes)
    pub const S_GB_ZEROFILL = 0xc;

    /// section with only pairs of function pointers for interposing
    pub const S_INTERPOSING = 0xd;

    /// section with only 16 byte literals
    pub const S_16BYTE_LITERALS = 0xe;

    /// section contains DTrace Object Format
    pub const S_DTRACE_DOF = 0xf;

    /// section with only lazy symbol pointers to lazy loaded dylibs
    pub const S_LAZY_DYLIB_SYMBOL_POINTERS = 0x10;

    // If a segment contains any sections marked with S_ATTR_DEBUG then all

    // sections in that segment must have this attribute.  No section other than

    // a section marked with this attribute may reference the contents of this

    // section.  A section with this attribute may contain no symbols and must have

    // a section type S_REGULAR.  The static linker will not copy section contents

    // from sections with this attribute into its output file.  These sections

    // generally contain DWARF debugging info.

    /// a debug section
    pub const S_ATTR_DEBUG = 0x02000000;

    /// section contains only true machine instructions
    pub const S_ATTR_PURE_INSTRUCTIONS = 0x80000000;

    /// section contains coalesced symbols that are not to be in a ranlib
    /// table of contents
    pub const S_ATTR_NO_TOC = 0x40000000;

    /// ok to strip static symbols in this section in files with the
    /// MH_DYLDLINK flag
    pub const S_ATTR_STRIP_STATIC_SYMS = 0x20000000;

    /// no dead stripping
    pub const S_ATTR_NO_DEAD_STRIP = 0x10000000;

    /// blocks are live if they reference live blocks
    pub const S_ATTR_LIVE_SUPPORT = 0x8000000;

    /// used with i386 code stubs written on by dyld
    pub const S_ATTR_SELF_MODIFYING_CODE = 0x4000000;

    /// section contains some machine instructions
    pub const S_ATTR_SOME_INSTRUCTIONS = 0x400;

    /// section has external relocation entries
    pub const S_ATTR_EXT_RELOC = 0x200;

    /// section has local relocation entries
    pub const S_ATTR_LOC_RELOC = 0x100;

    /// template of initial values for TLVs
    pub const S_THREAD_LOCAL_REGULAR = 0x11;

    /// template of initial values for TLVs
    pub const S_THREAD_LOCAL_ZEROFILL = 0x12;

    /// TLV descriptors
    pub const S_THREAD_LOCAL_VARIABLES = 0x13;

    /// pointers to TLV descriptors
    pub const S_THREAD_LOCAL_VARIABLE_POINTERS = 0x14;

    /// functions to call to initialize TLV values
    pub const S_THREAD_LOCAL_INIT_FUNCTION_POINTERS = 0x15;

    /// 32-bit offsets to initializers
    pub const S_INIT_FUNC_OFFSETS = 0x16;

    /// CPU type targeting 64-bit Intel-based Macs
    pub const CPU_TYPE_X86_64: cpu_type_t = 0x01000007;

    /// CPU type targeting 64-bit ARM-based Macs
    pub const CPU_TYPE_ARM64: cpu_type_t = 0x0100000C;

    /// All Intel-based Macs
    pub const CPU_SUBTYPE_X86_64_ALL: cpu_subtype_t = 0x3;

    /// All ARM-based Macs
    pub const CPU_SUBTYPE_ARM_ALL: cpu_subtype_t = 0x0;

    // The following are used to encode rebasing information

    pub const REBASE_TYPE_POINTER: u8 = 1;
    pub const REBASE_TYPE_TEXT_ABSOLUTE32: u8 = 2;
    pub const REBASE_TYPE_TEXT_PCREL32: u8 = 3;

    pub const REBASE_OPCODE_MASK: u8 = 0xF0;
    pub const REBASE_IMMEDIATE_MASK: u8 = 0x0F;
    pub const REBASE_OPCODE_DONE: u8 = 0x00;
    pub const REBASE_OPCODE_SET_TYPE_IMM: u8 = 0x10;
    pub const REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB: u8 = 0x20;
    pub const REBASE_OPCODE_ADD_ADDR_ULEB: u8 = 0x30;
    pub const REBASE_OPCODE_ADD_ADDR_IMM_SCALED: u8 = 0x40;
    pub const REBASE_OPCODE_DO_REBASE_IMM_TIMES: u8 = 0x50;
    pub const REBASE_OPCODE_DO_REBASE_ULEB_TIMES: u8 = 0x60;
    pub const REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB: u8 = 0x70;
    pub const REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB: u8 = 0x80;

    // The following are used to encode binding information

    pub const BIND_TYPE_POINTER: u8 = 1;
    pub const BIND_TYPE_TEXT_ABSOLUTE32: u8 = 2;
    pub const BIND_TYPE_TEXT_PCREL32: u8 = 3;

    pub const BIND_SPECIAL_DYLIB_SELF: i8 = 0;
    pub const BIND_SPECIAL_DYLIB_MAIN_EXECUTABLE: i8 = -1;
    pub const BIND_SPECIAL_DYLIB_FLAT_LOOKUP: i8 = -2;

    pub const BIND_SYMBOL_FLAGS_WEAK_IMPORT: u8 = 0x1;
    pub const BIND_SYMBOL_FLAGS_NON_WEAK_DEFINITION: u8 = 0x8;

    pub const BIND_OPCODE_MASK: u8 = 0xf0;
    pub const BIND_IMMEDIATE_MASK: u8 = 0x0f;
    pub const BIND_OPCODE_DONE: u8 = 0x00;
    pub const BIND_OPCODE_SET_DYLIB_ORDINAL_IMM: u8 = 0x10;
    pub const BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB: u8 = 0x20;
    pub const BIND_OPCODE_SET_DYLIB_SPECIAL_IMM: u8 = 0x30;
    pub const BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM: u8 = 0x40;
    pub const BIND_OPCODE_SET_TYPE_IMM: u8 = 0x50;
    pub const BIND_OPCODE_SET_ADDEND_SLEB: u8 = 0x60;
    pub const BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB: u8 = 0x70;
    pub const BIND_OPCODE_ADD_ADDR_ULEB: u8 = 0x80;
    pub const BIND_OPCODE_DO_BIND: u8 = 0x90;
    pub const BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB: u8 = 0xa0;
    pub const BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED: u8 = 0xb0;
    pub const BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB: u8 = 0xc0;

    pub const reloc_type_x86_64 = enum(u4) {
        /// for absolute addresses
        X86_64_RELOC_UNSIGNED = 0,

        /// for signed 32-bit displacement
        X86_64_RELOC_SIGNED,

        /// a CALL/JMP instruction with 32-bit displacement
        X86_64_RELOC_BRANCH,

        /// a MOVQ load of a GOT entry
        X86_64_RELOC_GOT_LOAD,

        /// other GOT references
        X86_64_RELOC_GOT,

        /// must be followed by a X86_64_RELOC_UNSIGNED
        X86_64_RELOC_SUBTRACTOR,

        /// for signed 32-bit displacement with a -1 addend
        X86_64_RELOC_SIGNED_1,

        /// for signed 32-bit displacement with a -2 addend
        X86_64_RELOC_SIGNED_2,

        /// for signed 32-bit displacement with a -4 addend
        X86_64_RELOC_SIGNED_4,

        /// for thread local variables
        X86_64_RELOC_TLV,
    };

    pub const reloc_type_arm64 = enum(u4) {
        /// For pointers.
        ARM64_RELOC_UNSIGNED = 0,

        /// Must be followed by a ARM64_RELOC_UNSIGNED.
        ARM64_RELOC_SUBTRACTOR,

        /// A B/BL instruction with 26-bit displacement.
        ARM64_RELOC_BRANCH26,

        /// Pc-rel distance to page of target.
        ARM64_RELOC_PAGE21,

        /// Offset within page, scaled by r_length.
        ARM64_RELOC_PAGEOFF12,

        /// Pc-rel distance to page of GOT slot.
        ARM64_RELOC_GOT_LOAD_PAGE21,

        /// Offset within page of GOT slot, scaled by r_length.
        ARM64_RELOC_GOT_LOAD_PAGEOFF12,

        /// For pointers to GOT slots.
        ARM64_RELOC_POINTER_TO_GOT,

        /// Pc-rel distance to page of TLVP slot.
        ARM64_RELOC_TLVP_LOAD_PAGE21,

        /// Offset within page of TLVP slot, scaled by r_length.
        ARM64_RELOC_TLVP_LOAD_PAGEOFF12,

        /// Must be followed by PAGE21 or PAGEOFF12.
        ARM64_RELOC_ADDEND,
    };

    /// This symbol is a reference to an external non-lazy (data) symbol.
    pub const REFERENCE_FLAG_UNDEFINED_NON_LAZY: u16 = 0x0;

    /// This symbol is a reference to an external lazy symbol—that is, to a function call.
    pub const REFERENCE_FLAG_UNDEFINED_LAZY: u16 = 0x1;

    /// This symbol is defined in this module.
    pub const REFERENCE_FLAG_DEFINED: u16 = 0x2;

    /// This symbol is defined in this module and is visible only to modules within this shared library.
    pub const REFERENCE_FLAG_PRIVATE_DEFINED: u16 = 3;

    /// This symbol is defined in another module in this file, is a non-lazy (data) symbol, and is visible
    /// only to modules within this shared library.
    pub const REFERENCE_FLAG_PRIVATE_UNDEFINED_NON_LAZY: u16 = 4;

    /// This symbol is defined in another module in this file, is a lazy (function) symbol, and is visible
    /// only to modules within this shared library.
    pub const REFERENCE_FLAG_PRIVATE_UNDEFINED_LAZY: u16 = 5;

    /// Must be set for any defined symbol that is referenced by dynamic-loader APIs (such as dlsym and
    /// NSLookupSymbolInImage) and not ordinary undefined symbol references. The strip tool uses this bit
    /// to avoid removing symbols that must exist: If the symbol has this bit set, strip does not strip it.
    pub const REFERENCED_DYNAMICALLY: u16 = 0x10;

    /// Used by the dynamic linker at runtime. Do not set this bit.
    pub const N_DESC_DISCARDED: u16 = 0x20;

    /// Indicates that this symbol is a weak reference. If the dynamic linker cannot find a definition
    /// for this symbol, it sets the address of this symbol to 0. The static linker sets this symbol given
    /// the appropriate weak-linking flags.
    pub const N_WEAK_REF: u16 = 0x40;

    /// Indicates that this symbol is a weak definition. If the static linker or the dynamic linker finds
    /// another (non-weak) definition for this symbol, the weak definition is ignored. Only symbols in a
    /// coalesced section (page 23) can be marked as a weak definition.
    pub const N_WEAK_DEF: u16 = 0x80;

    /// The N_SYMBOL_RESOLVER bit of the n_desc field indicates that the
    /// that the function is actually a resolver function and should
    /// be called to get the address of the real function to use.
    /// This bit is only available in .o files (MH_OBJECT filetype)
    pub const N_SYMBOL_RESOLVER: u16 = 0x100;

    // The following are used on the flags byte of a terminal node in the export information.

    pub const EXPORT_SYMBOL_FLAGS_KIND_MASK: u8 = 0x03;
    pub const EXPORT_SYMBOL_FLAGS_KIND_REGULAR: u8 = 0x00;
    pub const EXPORT_SYMBOL_FLAGS_KIND_THREAD_LOCAL: u8 = 0x01;
    pub const EXPORT_SYMBOL_FLAGS_KIND_ABSOLUTE: u8 = 0x02;
    pub const EXPORT_SYMBOL_FLAGS_KIND_WEAK_DEFINITION: u8 = 0x04;
    pub const EXPORT_SYMBOL_FLAGS_REEXPORT: u8 = 0x08;
    pub const EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER: u8 = 0x10;

    // An indirect symbol table entry is simply a 32bit index into the symbol table

    // to the symbol that the pointer or stub is refering to.  Unless it is for a

    // non-lazy symbol pointer section for a defined symbol which strip(1) as

    // removed.  In which case it has the value INDIRECT_SYMBOL_LOCAL.  If the

    // symbol was also absolute INDIRECT_SYMBOL_ABS is or'ed with that.

    pub const INDIRECT_SYMBOL_LOCAL: u32 = 0x80000000;
    pub const INDIRECT_SYMBOL_ABS: u32 = 0x40000000;

    // Codesign consts and structs taken from:

    // https://opensource.apple.com/source/xnu/xnu-6153.81.5/osfmk/kern/cs_blobs.h.auto.html

    /// Single Requirement blob
    pub const CSMAGIC_REQUIREMENT: u32 = 0xfade0c00;
    /// Requirements vector (internal requirements)
    pub const CSMAGIC_REQUIREMENTS: u32 = 0xfade0c01;
    /// CodeDirectory blob
    pub const CSMAGIC_CODEDIRECTORY: u32 = 0xfade0c02;
    /// embedded form of signature data
    pub const CSMAGIC_EMBEDDED_SIGNATURE: u32 = 0xfade0cc0;
    /// XXX
    pub const CSMAGIC_EMBEDDED_SIGNATURE_OLD: u32 = 0xfade0b02;
    /// Embedded entitlements
    pub const CSMAGIC_EMBEDDED_ENTITLEMENTS: u32 = 0xfade7171;
    /// Embedded DER encoded entitlements
    pub const CSMAGIC_EMBEDDED_DER_ENTITLEMENTS: u32 = 0xfade7172;
    /// Multi-arch collection of embedded signatures
    pub const CSMAGIC_DETACHED_SIGNATURE: u32 = 0xfade0cc1;
    /// CMS Signature, among other things
    pub const CSMAGIC_BLOBWRAPPER: u32 = 0xfade0b01;

    pub const CS_SUPPORTSSCATTER: u32 = 0x20100;
    pub const CS_SUPPORTSTEAMID: u32 = 0x20200;
    pub const CS_SUPPORTSCODELIMIT64: u32 = 0x20300;
    pub const CS_SUPPORTSEXECSEG: u32 = 0x20400;

    /// Slot index for CodeDirectory
    pub const CSSLOT_CODEDIRECTORY: u32 = 0;
    pub const CSSLOT_INFOSLOT: u32 = 1;
    pub const CSSLOT_REQUIREMENTS: u32 = 2;
    pub const CSSLOT_RESOURCEDIR: u32 = 3;
    pub const CSSLOT_APPLICATION: u32 = 4;
    pub const CSSLOT_ENTITLEMENTS: u32 = 5;
    pub const CSSLOT_DER_ENTITLEMENTS: u32 = 7;

    /// first alternate CodeDirectory, if any
    pub const CSSLOT_ALTERNATE_CODEDIRECTORIES: u32 = 0x1000;
    /// Max number of alternate CD slots
    pub const CSSLOT_ALTERNATE_CODEDIRECTORY_MAX: u32 = 5;
    /// One past the last
    pub const CSSLOT_ALTERNATE_CODEDIRECTORY_LIMIT: u32 = CSSLOT_ALTERNATE_CODEDIRECTORIES + CSSLOT_ALTERNATE_CODEDIRECTORY_MAX;

    /// CMS Signature
    pub const CSSLOT_SIGNATURESLOT: u32 = 0x10000;
    pub const CSSLOT_IDENTIFICATIONSLOT: u32 = 0x10001;
    pub const CSSLOT_TICKETSLOT: u32 = 0x10002;

    /// Compat with amfi
    pub const CSTYPE_INDEX_REQUIREMENTS: u32 = 0x00000002;
    /// Compat with amfi
    pub const CSTYPE_INDEX_ENTITLEMENTS: u32 = 0x00000005;

    pub const CS_HASHTYPE_SHA1: u8 = 1;
    pub const CS_HASHTYPE_SHA256: u8 = 2;
    pub const CS_HASHTYPE_SHA256_TRUNCATED: u8 = 3;
    pub const CS_HASHTYPE_SHA384: u8 = 4;

    pub const CS_SHA1_LEN: u32 = 20;
    pub const CS_SHA256_LEN: u32 = 32;
    pub const CS_SHA256_TRUNCATED_LEN: u32 = 20;

    /// Always - larger hashes are truncated
    pub const CS_CDHASH_LEN: u32 = 20;
    /// Max size of the hash we'll support
    pub const CS_HASH_MAX_SIZE: u32 = 48;

    pub const CS_SIGNER_TYPE_UNKNOWN: u32 = 0;
    pub const CS_SIGNER_TYPE_LEGACYVPN: u32 = 5;
    pub const CS_SIGNER_TYPE_MAC_APP_STORE: u32 = 6;

    pub const CS_ADHOC: u32 = 0x2;
    pub const CS_LINKER_SIGNED: u32 = 0x20000;

    pub const CS_EXECSEG_MAIN_BINARY: u32 = 0x1;

    /// This CodeDirectory is tailored specfically at version 0x20400.
    pub const CodeDirectory = extern struct {
        /// Magic number (CSMAGIC_CODEDIRECTORY)
        magic: u32,

        /// Total length of CodeDirectory blob
        length: u32,

        /// Compatibility version
        version: u32,

        /// Setup and mode flags
        flags: u32,

        /// Offset of hash slot element at index zero
        hashOffset: u32,

        /// Offset of identifier string
        identOffset: u32,

        /// Number of special hash slots
        nSpecialSlots: u32,

        /// Number of ordinary (code) hash slots
        nCodeSlots: u32,

        /// Limit to main image signature range
        codeLimit: u32,

        /// Size of each hash in bytes
        hashSize: u8,

        /// Type of hash (cdHashType* constants)
        hashType: u8,

        /// Platform identifier; zero if not platform binary
        platform: u8,

        /// log2(page size in bytes); 0 => infinite
        pageSize: u8,

        /// Unused (must be zero)
        spare2: u32,

        ///
        scatterOffset: u32,

        ///
        teamOffset: u32,

        ///
        spare3: u32,

        ///
        codeLimit64: u64,

        /// Offset of executable segment
        execSegBase: u64,

        /// Limit of executable segment
        execSegLimit: u64,

        /// Executable segment flags
        execSegFlags: u64,
    };

    /// Structure of an embedded-signature SuperBlob
    pub const BlobIndex = extern struct {
        /// Type of entry
        @"type": u32,

        /// Offset of entry
        offset: u32,
    };

    /// This structure is followed by GenericBlobs in no particular
    /// order as indicated by offsets in index
    pub const SuperBlob = extern struct {
        /// Magic number
        magic: u32,

        /// Total length of SuperBlob
        length: u32,

        /// Number of index BlobIndex entries following this struct
        count: u32,
    };

    pub const GenericBlob = extern struct {
        /// Magic number
        magic: u32,

        /// Total length of blob
        length: u32,
    };

    /// The LC_DATA_IN_CODE load commands uses a linkedit_data_command
    /// to point to an array of data_in_code_entry entries. Each entry
    /// describes a range of data in a code section.
    pub const data_in_code_entry = extern struct {
        /// From mach_header to start of data range.
        offset: u32,

        /// Number of bytes in data range.
        length: u16,

        /// A DICE_KIND value.
        kind: u16,
    };

    pub const LoadCommandIterator = struct {
        ncmds: usize,
        buffer: []align(@alignOf(u64)) const u8,
        index: usize = 0,

        pub const LoadCommand = struct {
            hdr: load_command,
            data: []const u8,

            pub fn cmd(lc: LoadCommand) LC {
                return lc.hdr.cmd;
            }

            pub fn cmdsize(lc: LoadCommand) u32 {
                return lc.hdr.cmdsize;
            }

            pub fn cast(lc: LoadCommand, comptime Cmd: type) ?Cmd {
                if (lc.data.len < @sizeOf(Cmd)) return null;
                return @ptrCast(*const Cmd, @alignCast(@alignOf(Cmd), &lc.data[0])).*;
            }

            /// Asserts LoadCommand is of type segment_command_64.
            pub fn getSections(lc: LoadCommand) []const section_64 {
                const segment_lc = lc.cast(segment_command_64).?;
                if (segment_lc.nsects == 0) return &[0]section_64{};
                const data = lc.data[@sizeOf(segment_command_64)..];
                const sections = @ptrCast(
                    [*]const section_64,
                    @alignCast(@alignOf(section_64), &data[0]),
                )[0..segment_lc.nsects];
                return sections;
            }

            /// Asserts LoadCommand is of type dylib_command.
            pub fn getDylibPathName(lc: LoadCommand) []const u8 {
                const dylib_lc = lc.cast(dylib_command).?;
                const data = lc.data[dylib_lc.dylib.name..];
                return mem.sliceTo(data, 0);
            }

            /// Asserts LoadCommand is of type rpath_command.
            pub fn getRpathPathName(lc: LoadCommand) []const u8 {
                const rpath_lc = lc.cast(rpath_command).?;
                const data = lc.data[rpath_lc.path..];
                return mem.sliceTo(data, 0);
            }
        };

        pub fn next(it: *LoadCommandIterator) ?LoadCommand {
            if (it.index >= it.ncmds) return null;

            const hdr = @ptrCast(
                *const load_command,
                @alignCast(@alignOf(load_command), &it.buffer[0]),
            ).*;
            const cmd = LoadCommand{
                .hdr = hdr,
                .data = it.buffer[0..hdr.cmdsize],
            };

            it.buffer = @alignCast(@alignOf(u64), it.buffer[hdr.cmdsize..]);
            it.index += 1;

            return cmd;
        }
    };