Question

我正在尝试从xlib屏幕保护程序中获取空闲时间

我尝试调试它，并且该行之后开始发生错误

dpy = xlib.XOpenDisplay(os.environ['DISPLAY'].encode('ascii'))

这是我的代码

class XScreenSaverInfo( ctypes.Structure):
    """ typedef struct { ... } XScreenSaverInfo; """
    _fields_ = [('window',      ctypes.c_ulong), # screen saver window
              ('state',       ctypes.c_int),   # off,on,disabled
              ('kind',        ctypes.c_int),   # blanked,internal,external
              ('since',       ctypes.c_ulong), # milliseconds
              ('idle',        ctypes.c_ulong), # milliseconds
              ('event_mask',  ctypes.c_ulong)] # events


xlib = ctypes.cdll.LoadLibrary('libX11.so')
dpy = xlib.XOpenDisplay(os.environ['DISPLAY'].encode('ascii'))
root = xlib.XDefaultRootWindow(dpy)
xss = ctypes.cdll.LoadLibrary( 'libXss.so')
xss.XScreenSaverAllocInfo.restype = ctypes.POINTER(XScreenSaverInfo)
xss_info = xss.XScreenSaverAllocInfo()
xss.XScreenSaverQueryInfo( dpy, root, xss_info)
print("Idle time in milliseconds: %d") % xss_info.contents.idle

我收到一个Segmentation fault (core dumped)错误。请帮忙：）

Answer 1

该错误是因为未指定 argtypes （和 restype ），如[Python 3.Docs]: ctypes - Specifying the required argument types (function prototypes)中所述。在这种情况下，有很多示例，其中有两个：

[SO]: python ctypes issue on different OSes (@CristiFati's answer)
[SO]: Python ctypes cdll.LoadLibrary, instantiate an object, execute its method, private variable address truncated (@CristiFati's answer)

在调用每个函数之前对它们声明它们：

xlib.XOpenDisplay.argtypes = [ctypes.c_char_p]
xlib.XOpenDisplay.restype = ctypes.c_void_p  # Actually, it's a Display pointer, but since the Display structure definition is not known (nor do we care about it), make it a void pointer

xlib.XDefaultRootWindow.argtypes = [ctypes.c_void_p]
xlib.XDefaultRootWindow.restype = ctypes.c_uint32

xss.XScreenSaverQueryInfo.argtypes = [ctypes.c_void_p, ctypes.c_uint32, ctypes.POINTER(XScreenSaverInfo)]
xss.XScreenSaverQueryInfo.restype = ctypes.c_int

在xlib上使用ctypes时出现分段错误

1 个答案: