在Python中加载共享库时未定义的符号

Undefined symbol when loading shared library in Python

本文关键字：未定义 符号 共享 Python 加载      更新时间：2023-10-16

我尝试使用一些python代码中的C 编写的共享库。我在Linux OS下。

首先，我使用以下命令创建共享库：

g++ -Wall -fPIC -O2 -c HeliosDacAPI.cpp
g++ -shared -o libHeliosDacAPI.so HeliosDacAPI.o

然后，我尝试将此库加载到Python控制台中：

>>> import ctypes
>>> HeliosLib = ctypes.cdll.LoadLibrary("./libHeliosDacAPI.so")

我有一个错误：

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.5/ctypes/__init__.py", line 425, in LoadLibrary
    return self._dlltype(name)
  File "/usr/lib/python3.5/ctypes/__init__.py", line 347, in __init__
    self._handle = _dlopen(self._name, mode)
OSError: ./libHeliosDacAPI.so: undefined symbol: _ZN9HeliosDac18GetControlResponseEiPhi

这是heliosdacapi.h

nm libHeliosDacAPI.so显示：

0000000000202088 B __bss_start
0000000000202088 b completed.7585
                 w __cxa_finalize@@GLIBC_2.2.5
0000000000202090 B dacController
0000000000000cb0 t deregister_tm_clones
0000000000000d40 t __do_global_dtors_aux
0000000000201dd8 t __do_global_dtors_aux_fini_array_entry
0000000000202078 d __dso_handle
0000000000202080 d DW.ref.__gxx_personality_v0
0000000000201de8 d _DYNAMIC
0000000000202088 D _edata
00000000002020a0 B _end
00000000000014b8 T _fini
0000000000000d80 t frame_dummy
0000000000201dd0 t __frame_dummy_init_array_entry
0000000000001758 r __FRAME_END__
0000000000202000 d _GLOBAL_OFFSET_TABLE_
                 w __gmon_start__
00000000000014dc r __GNU_EH_FRAME_HDR
                 U __gxx_personality_v0@@CXXABI_1.3
0000000000000bb0 T _init
0000000000202098 B inited
                 w _ITM_deregisterTMCloneTable
                 w _ITM_registerTMCloneTable
0000000000201de0 d __JCR_END__
0000000000201de0 d __JCR_LIST__
                 w _Jv_RegisterClasses
                 U __printf_chk@@GLIBC_2.3.4
0000000000000cf0 t register_tm_clones
                 U __stack_chk_fail@@GLIBC_2.4
0000000000202088 d __TMC_END__
                 U _Unwind_Resume@@GHeliosDac.cpp.0
0000000000001230 T _Z10SetShutterib
0000000000000db0 T _Z10WriteFrameiihP11HeliosPointi
0000000000001420 T _Z11OpenDevicesv
00000000000013d0 T _Z12CloseDevicesv
0000000000001360 T _Z13EraseFirmwarei
0000000000001290 T _Z18GetFirmwareVersioni
0000000000000f20 T _Z4Stopi
0000000000000f90 T _Z7GetNameiPc
00000000000010c0 T _Z7SetNameiPc
0000000000001150 T _Z9GetStatusi
                 U _ZdlPv@@GLIBCXX_3.4
                 U _ZN9HeliosDac11OpenDevicesEv
                 U _ZN9HeliosDac11SendControlEiPhi
                 U _ZN9HeliosDac18GetControlResponseEiPhi
                 U _ZN9HeliosDac9SendFrameEiPhi
                 U _ZN9HeliosDacC1Ev
                 U _ZN9HeliosDacD1Ev
                 U _Znwm@@GLIBCXX_3.4

我正在寻找有关如何调试此类问题的一些提示。

我无法确定，但是看来HeliosDac::GetControlResponse(int, ?*, int)是在CC_3中定义的，您不编译并链接到libHeliosDacAPI.so。

的确，从nm libHeliosDacAPI.so来看，我们清楚地看到了此符号，但U NDEFINE（这意味着您的问题不是来自您从Python加载库的方式）：

                 U _ZN9HeliosDac18GetControlResponseEiPhi

您可以尝试使用：

g++ -Wall -fPIC -O2 -c HeliosDacAPI.cpp
g++ -Wall -fPIC -O2 -c HeliosDac.cpp
g++ -shared -lusb -o libHeliosDacAPI.so HeliosDacAPI.o HeliosDac.o
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