Release history

macholib 1.16.2

  • Update classifiers for Python 3.11

macholib 1.16.1

  • Added some new CPU subtype definitions

macholib 1.16

  • Add allow_unknown_load_commands option to MachO and `macholib.MachOHeader.

    PR by github user bhamiltoncx.

macholib 1.15.2

  • Explicitly mention Python 3.10 in the project metadata

macholib 1.15.1

  • Remove a debug print introduced in the previous release.

macholib 1.15

  • Add support for new features in the macOS 11 SDK
  • Fix link to repository in README.rst
  • Fix macholib.dyld.dyld_find for system libraries on macOS 11 or later

macholib 1.14

  • Repository moved to GitHub
  • #32: Update the LC_NAMES table

macholib 1.13

# 31: Add two new load commands introduced in macOS 10.15

macholib 1.12

  • #27: Missing describe method for build_version_command

macholib 1.11

  • Add very hacky limited support for @loader_path. This is just enough to deal with extensions and dylibs found in Python binary wheels.

macholib 1.10

  • #25: Add support for LC_NOTE and LC_BUILD_VERSION

macholib 1.9


  • Add definition for macholib.mach_o.reloc_type_generic, which was used in code but never defined.

  • #22: Add LICENSE file

  • #23: Added “–help” option for “python -m macholib”

  • Added function macholib.MachO.lc_str_value which should help in decoding value of macholib.mach_o.lc_str. Those values are offsets in the data of a load command, the function will return the actually value as a byte string.

    See also issue #21.

Bug fixes:

  • Pull request #15: Fix typo in thread_command class

    Patch by user “phdphuc” on bitbucket.

macholib 1.8

  • Use the same dependency walk logic as otool

    Patch by Taras Tsugrii <>

  • Added support for new load commands

    Patch by David Dorsey <>, with enhancements by Ronald Oussoren.

  • Fix procesing DSYM file from XCODE 6.x

    Patch by HolmsBlazhey <>

  • MachOGraph.locate(): When calling dyld_find(), use kwarg ‘loader_path’, not ‘loader’.

    Patch by Stuart Berg <>

  • Add fields to thread_command

    Patch by Asger Hautop Drewsen <>

  • Add missing ARM_V7S subtype.

    Patch by “NN”

  • Fix for SymbolTable

    Patch by Christian Klein <>

  • Use first Mach-O header as the default header

    Patch by Christian Klein <>

  • Issue #17: add LC_LOAD_UPWARD_DYLIB to _RELOCATABLE set

  • Issue #16: macholib “hangs” on invalid input

    Due to the use of the range function on untrusted input the python process could hang when reading invalid input, due to trying to construct an enormous list.

  • Issue #18: Bad version parsing in macho_version_helper

    The order of subfields in mach_version_helper was reversed from reality.

  • Issue #19: Fix aligment issue that prevented code signing

    Patch by Brendan Simon

  • Fix issue #14: Can’t pass endian argument to p_uint64.from_str

macholib 1.7

  • Added support for ARM64, LC_ENCRYPTION_INFO_64 and LC_LINKER_OPTION

    Patch by Matthias Ringwald.

  • Load commands now have a “describe” method that returns more information about the command.

    Patch by David Dorsey.

  • The MAGIC value in the header was always represented in the native byte order, instead of as the value read from the binary.

    Patch by David Dorsey.

  • Added various new constants to “macholib.mach_o”.

    Patch by David Dorsey.

macholib 1.6.1

  • ?

macholib 1.6

  • Add support for @loader_path’ link command in macholib.dyld:

    • Added function macholib.dyld.dyld_loader_search
    • This function is used by macholib.dyld.dyld_find, and that function now has an new (optional) argument with the path to the loader.
  • Also add support for @loader_path’ to macholib.MachoGraph, using the newly added @loader_path’ support in the dyld module.

    Due to this suppport the macho_standalone tool can now rewrite binaries that contain an @loader_path’ load command.

macholib 1.5.2

  • Issue #93: Show the name of the affected file in the exception message for Mach-O headers that are too large to relocate.

macholib 1.5.1

  • There were no ‘classifiers’ in the package metadata due to a bug in

macholib 1.5

macholib 1.5 is a minor feature release

  • No longer use 2to3 to provide Python 3 support

    As a side-effect of this macholib no longer supports Python 2.5 and earlier.

  • Adds suppport for some new macho load commands

  • Fix for py3k problem in

    Patch by Guanqun Lu.

  • Fix for some issues in

    Patch by Nam Nguyen

  • Issue #10: Fix for LC_DATA_IN_CODE linker commands, without this fix py2app cannot build application bundles when the source binaries have been compiled with Xcode 4.5.

  • Issue #6: Fix for LC_ENCRYPTION_INFO linker commands

  • Use the mach header information to print the cpu type of a binary, instead of trying to deduce that from pointer width and endianness.

    Changed the code because of issue #6, in which a user tries to dump a iOS binary which results in bogus output in the previous releases.

  • The mapping macholib.macho_dump.ARCH_MAP is undocumented and no longer used by macholib itself. It will be removed in the next release.

  • The command-line tools macho_find, macho_dump and macho_standalone are deprecated. Use “python -mmacholib” instead. That is:

    $ python -mmacholib dump /usr/bin/grep
    $ python -mmacholib find ~
    $ python -mmacholib standalone

    This makes it clearer which version of the tools are used.

macholib 1.4.3

macholib 1.4.3 is a minor feature release

  • Added strings for ‘x86_64’ and ‘ppc64’ to macholib.mach_o.CPU_TYPE_NAMES.

  • macho_find and macho_dump were broken in the 1.4.2 release

  • added ‘macholib.util.NOT_SYSTEM_FILES’, a list of files that aren’t system path’s even though they are located in system locations.

    Needed to work around a bug in PySide (see issue #32 in the py2app tracker)

macholib 1.4.2

macholib 1.4.2 is a minor bugfix release

  • The support for new load commands that was added in 1.4.1 contained a typo that caused problems on OSX 10.7 (Lion).

macholib 1.4.1

macholib 1.4.1 is a minor feature release


  • Add support for a number of new MachO load commands that were added during the lifetime of OSX 10.6: LC_LOAD_UPWARD_DYLIB, LC_VERSION_MIN_MACOSX, LC_VERSION_MIN_IPHONEOS and LC_FUNCTION_STARTS.

macholib 1.4

macholib 1.4 is a feature release


  • Documentation is now generated using sphinx and can be viewed at <>.

  • The repository has moved to bitbucket

  • There now is a testsuite

  • Private functionality inside modules was renamed to a name starting with an underscore.


    if this change affects your code you are relying on undefined implementation features, please stop using private functions.

  • The basic packable types in macholib.ptypes were renamed to better represent the corresponding C type. The table below lists the old an new names (the old names are still available, but are deprecated and will be removed in a future release).

    Old name New name
    p_byte p_int8
    p_ubyte p_uint8
    p_short p_int16
    p_ushort p_uint16
    p_int p_int32
    p_uint p_uint32
    p_long p_int32
    p_ulong p_uint32
    p_longlong p_int64
    p_ulonglong p_uint64

    Macholib.ptypes.p_ptr is no longer present as it had an unclear definition and isn’t actually used in the codebase.

Bug fixes:

  • The semantics of dyld.dyld_default_search were changed a bit, it now first searches the framework path (if appropriate) and then the linker path, irrespective of the value of the DYLD_FALLBACK* environment variables.

    Previous versions would change the search order when those variables was set, which is odd and doesn’t correspond with the documented behaviour of the system dyld.

  • It is once again possible to install using python2.5

  • The source distribution includes all files, this was broken due to the switch to mercurial (which confused setuptools)

macholib 1.3

macholib 1.3 is a feature release.


  • Experimental Python 3.x support

    This version contains lightly tested support for Python 3.

macholib 1.2.2

macholib 1.2.2 is a bugfix release.

Bug fixes:

  • Macholib should work better with 64-bit code (patch by Marc-Antoine Parent)