如何在Python中从SXS加载C DLL？

Question

这通常通过在驻留在可执行文件中的清单文件中指定DLL依赖项来完成。但是，我不知道如何用Python实现这一点。加载DLL不是问题，而是在SXS中找到要加载的适当DLL才是问题。

是否有指定在何处找到DLL的标准过程？对于这个例子，让我们假设它存在于这里：

c:\windows\winsxs\amd64_my_handy_lib_<public_key_token>_1.0.0.0_none_<some_ID>

是否真的需要手动搜索c:\windows\winsxs目录，按名称查找DLL，然后检查父目录是否包含正确的版本？

我只是没有做足够的Python项目来了解实现这个目标的适当方法。

Answer 1

下面是一个从WinSxS目录加载CRT的示例。

actctx.manifest:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
    <dependency>
        <dependentAssembly>
            <assemblyIdentity
                type="win32"
                name="Microsoft.VC90.CRT"
                version="9.0.21022.8"
                processorArchitecture="amd64"
                publicKeyToken="1fc8b3b9a1e18e3b">
            </assemblyIdentity>
        </dependentAssembly>
    </dependency>
</assembly>

actctx.py:

from ctypes import *
from ctypes.wintypes import *

kernel32 = WinDLL("kernel32", use_last_error=True)

ACTCTX_FLAG_PROCESSOR_ARCHITECTURE_VALID = 0x001
ACTCTX_FLAG_LANGID_VALID = 0x002
ACTCTX_FLAG_ASSEMBLY_DIRECTORY_VALID = 0x004
ACTCTX_FLAG_RESOURCE_NAME_VALID = 0x008
ACTCTX_FLAG_SET_PROCESS_DEFAULT = 0x010
ACTCTX_FLAG_APPLICATION_NAME_VALID = 0x020
ACTCTX_FLAG_HMODULE_VALID = 0x080
DEACTIVATE_ACTCTX_FLAG_FORCE_EARLY_DEACTIVATION = 1

INVALID_HANDLE_VALUE = HANDLE(-1).value
ULONG_PTR = WPARAM  # pointer-sized unsigned integer

class ACTCTX(Structure):
    _fields_ = (("cbSize", ULONG),
                ("dwFlags", DWORD),
                ("lpSource", LPCWSTR),
                ("wProcessorArchitecture", USHORT),
                ("wLangId", LANGID),
                ("lpAssemblyDirectory", LPCWSTR),
                ("lpResourceName", LPCWSTR),
                ("lpApplicationName", LPCWSTR),
                ("hModule", HMODULE))

    def __init__(self, *args, **kwds):
        super(ACTCTX, self).__init__(sizeof(self), *args, **kwds)

CreateActCtxW = kernel32.CreateActCtxW
CreateActCtxW.restype = HANDLE
CreateActCtxW.argtypes = (POINTER(ACTCTX),)
ReleaseActCtx = kernel32.ReleaseActCtx
ReleaseActCtx.restype = None
ReleaseActCtx.argtypes = (HANDLE,)
ActivateActCtx = kernel32.ActivateActCtx
ActivateActCtx.argtypes = (HANDLE, POINTER(ULONG_PTR))
DeactivateActCtx = kernel32.DeactivateActCtx
DeactivateActCtx.argtypes = (DWORD, ULONG_PTR)

if __name__ == "__main__":
    manifest_path = "actctx.manifest" # keep ref
    ctx = ACTCTX(lpSource=manifest_path)
    hActCtx = CreateActCtxW(byref(ctx))
    if hActCtx == INVALID_HANDLE_VALUE:
        raise WinError(get_last_error())

    cookie = ULONG_PTR()
    if not ActivateActCtx(hActCtx, byref(cookie)):
        raise WinError()
    msvcr90 = CDLL("msvcr90")
    if not DeactivateActCtx(0, cookie):
        raise WinError(get_last_error())

    ReleaseActCtx(hActCtx)

    # show DLL path
    hModule = HANDLE(msvcr90._handle)
    path = (c_wchar * 260)()    
    kernel32.GetModuleFileNameW(hModule, path, len(path))
    print(path.value)

输出：

C:\Windows\WinSxS\amd64_microsoft.vc90.crt_1fc8b3b9a1e18e3b_9.0.30729.6161_none_08e61857a83bc251\msvcr90.DLL

这在Python3.4.2下进行了测试，它使用VS 2010构建，并使用msvcr100.dll进行链接。因此，至少在这种情况下，真正需要设置激活上下文，否则在ERROR_MOD_NOT_FOUND中加载msvcr90.dll就会失败。