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Generate python ctypes classes from C headers. Requires LLVM clang
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ctypeslib with libclang

Build Status Coverage Status Code Health Latest release Supported versions

Quick usage guide in the docs/ folder.

Status update

  • 2018-01-03: master branch works with libclang-5.0 HEAD, python clang from pypi, python3
  • 2017-05-01: master branch works with libclang-4.0 HEAD


On Ubuntu, libclang libraries are installed with versions. This library tries to load a few different versions to help you out. ( But if you encounter a version compatibility issue, you might have to fix the problem using one of the following solutions:

  1. Install libclang-5.0-dev to get (maybe)
  2. OR create a link to named
  3. OR hardcode a call to clang.cindex.Config.load_library_file('') in your code


Stable Distribution is available through PyPi at

sudo pip install ctypeslib2

Setting up clang >= 3.7 dependency

See the LLVM Clang instructions at or use your distribution's packages.


Look at test/

Other example:

Source file:

$ cat t.c 
struct my_bitfield
  long a:3;
  long b:4;
  unsigned long long c:3;
  unsigned long long d:3;
  long f:2;
} ;

Run c-to-python script: clang2py t.c Output:

# -*- coding: utf-8 -*-
# TARGET arch is: []
# WORD_SIZE is: 8
import ctypes

class struct_my_bitfield(ctypes.Structure):
    _pack_ = True # source:False
    _fields_ = [
    ('a', ctypes.c_int64, 3),
    ('b', ctypes.c_int64, 4),
    ('c', ctypes.c_int64, 3),
    ('d', ctypes.c_int64, 3),
    ('f', ctypes.c_int64, 2),
    ('PADDING_0', ctypes.c_int64, 49),

__all__ = \

Other example with headers:

Source file:

$ cat test-stdbool.c 
#include <stdbool.h>

typedef struct s_foo {
    bool bar1;
    bool bar2;
    bool bar3;
} foo;

Run c-to-python script (with any relevant include folder): clang2py --clang-args="-I/usr/include/clang/4.0/include" test-stdbool.c


# -*- coding: utf-8 -*-
# TARGET arch is: ['-I/usr/include/clang/4.0/include']
# WORD_SIZE is: 8
import ctypes

class struct_s_foo(ctypes.Structure):
    _pack_ = True # source:False
    _fields_ = [
    ('bar1', ctypes.c_bool),
    ('bar2', ctypes.c_bool),
    ('bar3', ctypes.c_bool),

foo = struct_s_foo
__all__ = \
    ['struct_s_foo', 'foo']


usage: clang2py [-h] [-c] [-d] [--debug] [-e] [-k TYPEKIND] [-i] [-l DLL]
                [-m module] [-o OUTPUT] [-p DLL] [-q] [-r EXPRESSION]
                [-s SYMBOL] [-t TARGET] [-v] [-V] [-w W] [-x]
                [--show-ids SHOWIDS] [--max-depth N] [--clang-args CLANG_ARGS]
                files [files ...]

Version 2.1.5rc0. Generate python code from C headers

positional arguments:
  files                 source filenames. stdin is not supported

optional arguments:
  -h, --help            show this help message and exit
  -c, --comments        include source doxygen-style comments
  -d, --doc             include docstrings containing C prototype and source
                        file location
  --debug               setLevel to DEBUG
  -e, --show-definition-location
                        include source file location in comments
                        kind of type descriptions to include: a = Alias, c =
                        Class, d = Variable, e = Enumeration, f = Function, m
                        = Macro, #define s = Structure, t = Typedef, u = Union
                        default = 'cdefstu'
  -i, --includes        include declaration defined outside of the sourcefiles
  -l DLL, --include-library DLL
                        library to search for exported functions. Add multiple
                        times if required
  -m module, --module module
                        Python module(s) containing symbols which will be
                        imported instead of generated
  -o OUTPUT, --output OUTPUT
                        output filename (if not specified, standard output
                        will be used)
  -p DLL, --preload DLL
                        dll to be loaded before all others (to resolve
  -q, --quiet           Shut down warnings and below
                        regular expression for symbols to include (if neither
                        symbols nor expressions are specified,everything will
                        be included)
  -s SYMBOL, --symbol SYMBOL
                        symbol to include (if neither symbols nor expressions
                        are specified,everything will be included)
  -t TARGET, --target TARGET
                        target architecture (default: x86_64-Linux)
  -v, --verbose         verbose output
  -V, --version         show program's version number and exit
  -w W                  add all standard windows dlls to the searched dlls
  -x, --exclude-includes
                        Parse object in sources files only. Ignore includes
  --show-ids SHOWIDS    Don't compute cursor IDs (very slow)
  --max-depth N         Limit cursor expansion to depth N
  --clang-args CLANG_ARGS
                        clang options, in quotes: --clang-args="-std=c99

Cross-architecture: You can pass target modifiers to clang. For example, try
--clang-args="-target x86_64" or "-target i386-linux" to change the target CPU

Inner workings for memo

  • clang2py is a script that calls ctypeslib/ctypeslib/
  • is mostly the old module forked to use libclang.
  • calls ctypeslib/ctypeslib/codegen/
  • calls ctypeslib/ctypeslib/codegen/
  • uses libclang's python binding to access the clang internal representation of the C source code. It then translate each child of the AST tree to python objects as listed in typedesc.
  • then uses these python object to generate ctypes-based python source code.

Because clang is capable to handle different target architecture, this fork {is/should be} able to produce cross-platform memory representation if needed.


This fork of ctypeslib is mainly about using the libclang1>=3.7 python bindings to generate python code from C source code, instead of gccxml.

the original ctypeslib contains these packages:

  • ctypeslib.codegen - a code generator
  • ctypeslib.contrib - various contributed modules
  • ctypeslib.util - assorted small helper functions
  • ctypeslib.test - unittests

This fork of ctypeslib is heavily patched for clang.

The original ctypeslib is written by

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