193 lines
6.7 KiB
Python
193 lines
6.7 KiB
Python
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# -*- coding: utf-8 -*-
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#
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# Copyright 2009-2017 Wander Lairson Costa
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# Copyright 2009-2021 PyUSB contributors
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are
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# met:
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#
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# 1. Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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#
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# 2. Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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#
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# 3. Neither the name of the copyright holder nor the names of its
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# contributors may be used to endorse or promote products derived from
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# this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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# HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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import ctypes
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import ctypes.util
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import logging
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import sys
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__all__ = [
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'LibraryException',
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'LibraryNotFoundException',
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'NoLibraryCandidatesException',
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'LibraryNotLoadedException',
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'LibraryMissingSymbolsException',
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'locate_library',
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'load_library',
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'load_locate_library'
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]
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_LOGGER = logging.getLogger('usb.libloader')
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class LibraryException(OSError):
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pass
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class LibraryNotFoundException(LibraryException):
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pass
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class NoLibraryCandidatesException(LibraryNotFoundException):
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pass
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class LibraryNotLoadedException(LibraryException):
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pass
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class LibraryMissingSymbolsException(LibraryException):
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pass
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def locate_library (candidates, find_library=ctypes.util.find_library):
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"""Tries to locate a library listed in candidates using the given
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find_library() function (or ctypes.util.find_library).
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Returns the first library found, which can be the library's name
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or the path to the library file, depending on find_library().
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Returns None if no library is found.
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arguments:
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* candidates -- iterable with library names
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* find_library -- function that takes one positional arg (candidate)
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and returns a non-empty str if a library has been found.
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Any "false" value (None,False,empty str) is interpreted
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as "library not found".
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Defaults to ctypes.util.find_library if not given or
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None.
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"""
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if find_library is None:
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find_library = ctypes.util.find_library
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use_dll_workaround = (
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sys.platform == 'win32' and find_library is ctypes.util.find_library
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)
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for candidate in candidates:
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# Workaround for CPython 3.3 issue#16283 / pyusb #14
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if use_dll_workaround:
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candidate += '.dll'
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libname = find_library(candidate)
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if libname:
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return libname
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# -- end for
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return None
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def load_library(lib, name=None, lib_cls=None):
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"""Loads a library. Catches and logs exceptions.
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Returns: the loaded library or None
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arguments:
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* lib -- path to/name of the library to be loaded
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* name -- the library's identifier (for logging)
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Defaults to None.
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* lib_cls -- library class. Defaults to None (-> ctypes.CDLL).
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"""
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try:
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if lib_cls:
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return lib_cls(lib)
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else:
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return ctypes.CDLL(lib)
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except Exception:
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if name:
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lib_msg = '%s (%s)' % (name, lib)
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else:
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lib_msg = lib
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lib_msg += ' could not be loaded'
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if sys.platform == 'cygwin':
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lib_msg += ' in cygwin'
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_LOGGER.error(lib_msg, exc_info=True)
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return None
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def load_locate_library(candidates, cygwin_lib, name,
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win_cls=None, cygwin_cls=None, others_cls=None,
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find_library=None, check_symbols=None):
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"""Locates and loads a library.
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Returns: the loaded library
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arguments:
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* candidates -- candidates list for locate_library()
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* cygwin_lib -- name of the cygwin library
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* name -- lib identifier (for logging). Defaults to None.
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* win_cls -- class that is used to instantiate the library on
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win32 platforms. Defaults to None (-> ctypes.CDLL).
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* cygwin_cls -- library class for cygwin platforms.
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Defaults to None (-> ctypes.CDLL).
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* others_cls -- library class for all other platforms.
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Defaults to None (-> ctypes.CDLL).
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* find_library -- see locate_library(). Defaults to None.
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* check_symbols -- either None or a list of symbols that the loaded lib
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must provide (hasattr(<>)) in order to be considered
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valid. LibraryMissingSymbolsException is raised if
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any symbol is missing.
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raises:
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* NoLibraryCandidatesException
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* LibraryNotFoundException
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* LibraryNotLoadedException
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* LibraryMissingSymbolsException
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"""
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if sys.platform == 'cygwin':
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if cygwin_lib:
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loaded_lib = load_library(cygwin_lib, name, cygwin_cls)
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else:
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raise NoLibraryCandidatesException(name)
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elif candidates:
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lib = locate_library(candidates, find_library)
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if lib:
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if sys.platform == 'win32':
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loaded_lib = load_library(lib, name, win_cls)
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else:
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loaded_lib = load_library(lib, name, others_cls)
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else:
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_LOGGER.error('%r could not be found', (name or candidates))
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raise LibraryNotFoundException(name)
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else:
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raise NoLibraryCandidatesException(name)
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if loaded_lib is None:
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raise LibraryNotLoadedException(name)
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elif check_symbols:
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symbols_missing = [
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s for s in check_symbols if not hasattr(loaded_lib, s)
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]
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if symbols_missing:
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msg = ('%r, missing symbols: %r', lib, symbols_missing )
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_LOGGER.error(msg)
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raise LibraryMissingSymbolsException(lib)
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else:
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return loaded_lib
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else:
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return loaded_lib
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