Container package for libusb

This Python package functions as an installation vehicle for libusb shared libraries, to simplify installation of tools that require libusb. The main use case is so that users don't have to install libusb manually for projects that use pyusb. However, any Python project that uses a libusb wrapper can also benefit.

See libusb.info for more information about libusb.

Note: Currently the included libusb is built without udev support on Linux.

Note: The libusb upstream git repository is included as a submodule, so you need to clone with submodules enabled. You can either clone with --recurse-submodules or run git submodule update --init after cloning.

Installation

All releases include wheels for Linux, macOS, and Windows for multiple architectures. In addition, a source distribution is released.

If a matching wheel is not available, the source distribution will be installed and libusb will be compiled. This means the libusb build requirements must be installed:

• Linux and macOS: autoconf, automake, libtool, and m4. As mentioned above, libusb is built without udev support, so libudev-dev is not required on Linux.
• Windows: Visual Studio 2019 (Community is ok).

If the libusb build fails when installing from a source distribution, the libusb-package install will still succeed. In this case, an "empty" libusb-package is installed that doesn't contain a libusb shared library. get_library_path() returns None and find_library() falls back to returning a system installation of libusb, if available.

You can also install from a clone of the git repository by running pip install . from the repository root directory. Editable installs are supported. Please note that running setup.py directly is no longer supported for PEP 517 compliant packages. When building from the repo, because libusb 1.0.24 does not support out of tree builds, the build is done in-place in the src/libusb directory. make clean is run before compiling to ensure a clean build.

APIs

There are four public functions exported by libusb_package.

• find(*args, **kwargs): Wrapper around pyusb's usb.core.find() that sets the backend parameter to a libusb1 backend created from the libusb library included in libusb_package. All other parameters are passed unmodified

• get_libusb1_backend(): Returns a pyusb backend object for the libusb version contained in libusb_package.

• find_library(candidate): Lower level function that returns either the full path to a library contained in libusb_package with a name starting with candidate, or None if no matching library is found. This function is suitable for use with the find_library callback parameter for pyusb's get_backend() functions.

  If get_library_path() returns None, indicating there is no included library, this function will fall back to ctypes.util.find_library().

• get_library_path(): Returns an absolute Path object for the included library. If there is not an included library, None is returned.

Both get_libusb1_backend() and get_library_path() cache their return values.

Versioning

The version of libusb-package is composed of the libusb version plus an additional field for the version of the Python code. For instance, 1.0.24.0. The Python code version will be reset to 0 when the libusb version is incremented for new libusb release.

Examples

Usage example for find():

import libusb_package

for dev in libusb_package.find(find_all=True):
    print(dev)

Usage example for find_library():

import libusb_package
import usb.core
import usb.backend.libusb1

libusb1_backend = usb.backend.libusb1.get_backend(find_library=libusb_package.find_library)
# -> calls usb.libloader.load_locate_library(
#                ('usb-1.0', 'libusb-1.0', 'usb'),
#                'cygusb-1.0.dll', 'Libusb 1',
#                win_cls=win_cls,
#                find_library=find_library, check_symbols=('libusb_init',))
#
# -> calls find_library(candidate) with candidate in ('usb-1.0', 'libusb-1.0', 'usb')
#   returns lib name or path (as appropriate for OS) if matching lib is found

# It would also be possible to pass the output of libusb_package.get_libsusb1_backend()
# to the backend parameter here. In fact, that function is simply a shorthand for the line
# above.
print(list(usb.core.find(find_all=True, backend=libusb1_backend)))

Source distribution

Before building a source distribution, be sure to clean all untracked files from the libusb submodule using git -C src/libusb clean -dfx.

License

The Python code for libusb-package is licensed with Apache 2.0.
The libusb library and its source code are licensed with GPLv2.