链接器错误 Lunatic Python lua.require('socket') ->未定义符号:lua_getmetatable [英] Linker Error Lunatic Python lua.require('socket') -> undefined symbol: lua_getmetatable

问题描述

我有一个依赖于一些 lua 文件的 python 项目，其中之一需要套接字".当我尝试从 python 2.7 中要求 lua 文件时，我在加载 socket.core未定义符号:lua_getmetatable"时遇到错误.

I have a python project that relies on some lua files, one of which requires 'socket'. I get an error loading socket.core "undefined symbol: lua_getmetatable" when I try to require that lua file from python 2.7.

简单的复制器:

$ python
Python 2.7.1+ (r271:86832, Apr 11 2011, 18:13:53) 
[GCC 4.5.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import lua
>>> lua.require('socket')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
Exception: error: error loading module 'socket.core' from file 
    '/usr/lib/lua/5.1/socket/core.so':
    /usr/lib/lua/5.1/socket/core.so: undefined symbol: lua_getmetatable

我正在使用 最近的 Lunatic Python 分支，在那里我清理了 Py_ssize_t 警告和 liblua5.1-socket2 在 Ubuntu 11.04 上

I am using a recent Lunatic Python branch where I cleaned up the Py_ssize_t warnings, and liblua5.1-socket2 on Ubuntu 11.04

如果我使用主要的 lunatic-python 源代码和/或升级到 luasocket 2.0，我会遇到同样的错误.2.

I get the same error if I use the main lunatic-python source code and/or upgrade to luasocket 2.0.2.

导致此错误的原因是什么，我该如何解决?

edit: What is causing this error, and how do I fix it?

编辑 #2:这是构建 luasocket-2.0.2 的输出.默认的 make 没有构建 unix.so，我编辑它来构建它，所以我没有将 2.0.0 与 2.0.2 混合和匹配:

edit #2: Here is the output of building luasocket-2.0.2. The default make did not build unix.so, and I edited it to build that as well so I didn't mix and match 2.0.0 with 2.0.2:

$ make
cd src; make all
make[1]: Entering directory `/sandbox/luasocket/luasocket-2.0.2/src'
gcc -I/usr/include/lua5.1 -DLUASOCKET_DEBUG  -pedantic -Wall -O2 -fpic -llua   -c -o luasocket.o luasocket.c
gcc -I/usr/include/lua5.1 -DLUASOCKET_DEBUG  -pedantic -Wall -O2 -fpic -llua   -c -o timeout.o timeout.c
gcc -I/usr/include/lua5.1 -DLUASOCKET_DEBUG  -pedantic -Wall -O2 -fpic -llua   -c -o buffer.o buffer.c
gcc -I/usr/include/lua5.1 -DLUASOCKET_DEBUG  -pedantic -Wall -O2 -fpic -llua   -c -o io.o io.c
gcc -I/usr/include/lua5.1 -DLUASOCKET_DEBUG  -pedantic -Wall -O2 -fpic -llua   -c -o auxiliar.o auxiliar.c
gcc -I/usr/include/lua5.1 -DLUASOCKET_DEBUG  -pedantic -Wall -O2 -fpic -llua   -c -o options.o options.c
gcc -I/usr/include/lua5.1 -DLUASOCKET_DEBUG  -pedantic -Wall -O2 -fpic -llua   -c -o inet.o inet.c
gcc -I/usr/include/lua5.1 -DLUASOCKET_DEBUG  -pedantic -Wall -O2 -fpic -llua   -c -o tcp.o tcp.c
gcc -I/usr/include/lua5.1 -DLUASOCKET_DEBUG  -pedantic -Wall -O2 -fpic -llua   -c -o udp.o udp.c
gcc -I/usr/include/lua5.1 -DLUASOCKET_DEBUG  -pedantic -Wall -O2 -fpic -llua   -c -o except.o except.c
gcc -I/usr/include/lua5.1 -DLUASOCKET_DEBUG  -pedantic -Wall -O2 -fpic -llua   -c -o select.o select.c
gcc -I/usr/include/lua5.1 -DLUASOCKET_DEBUG  -pedantic -Wall -O2 -fpic -llua   -c -o usocket.o usocket.c
gcc  -O -shared -fpic -o socket.so.2.0.2 luasocket.o timeout.o buffer.o io.o auxiliar.o options.o inet.o tcp.o udp.o except.o select.o usocket.o 
gcc -I/usr/include/lua5.1 -DLUASOCKET_DEBUG  -pedantic -Wall -O2 -fpic -llua   -c -o mime.o mime.c
gcc  -O -shared -fpic -o mime.so.1.0.2 mime.o 
gcc -I/usr/include/lua5.1 -DLUASOCKET_DEBUG  -pedantic -Wall -O2 -fpic -llua   -c -o unix.o unix.c
gcc  -O -shared -fpic -o unix.so buffer.o auxiliar.o options.o timeout.o io.o usocket.o unix.o
make[1]: Leaving directory `/sandbox/luasocket/luasocket-2.0.2/src'

推荐答案

问题不在于 luasocket，而在于共享库中符号的处理方式.

The problem is not in luasocket, but in the way symbols from shared libraries are handled.

问题是lua.so(Python模块)链接到liblua5.1.so，require加载的共享模块> 无法访问 liblua5.1.so 中的符号.在 Mac OS X 上，这是有效的，因为 dlopen 中的符号默认加载为 RTLD_GLOBAL.

The problem is that the while the lua.so (Python module) links to liblua5.1.so, shared modules loaded by require do not have access to the symbols from liblua5.1.so. On Mac OS X this works, because symbols from dlopen are loaded as RTLD_GLOBAL by default.

我已经尝试修改 Lua 源代码 (lua-5.1.4/src/loadlib.c:69)，但是它没有帮助，因为到时候 requirecode>是从lua.so调用的，liblua5.1.so的符号已经在本地为lua.so加载了.这就是 luasocket 看不到它们的原因.

I have experimented with modifying the Lua source (lua-5.1.4/src/loadlib.c:69), however it does not help, because by the time require is called from lua.so, the symbols from liblua5.1.so have already been loaded locally for lua.so. This is why luasocket does not see them.

幸运的是，Python 允许您使用 sys 模块更改 dlopen 语义.这允许您强制加载带有 RTLD_GLOBAL 的模块，这正是所需要的.尝试运行以下代码，看看它是否适合您:

Fortunately, Python allows you to change the dlopen semantics using the sys module. This allows you to force to load modules with RTLD_GLOBAL, which is exactly what is needed. Try running the following code and see if it works for you:

$ python
Python 2.7.1+ (r271:86832, Apr 11 2011, 18:13:53) 
[GCC 4.5.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys, DLFCN
>>> sys.setdlopenflags(DLFCN.RTLD_NOW | DLFCN.RTLD_GLOBAL)
>>> import lua
>>> lua.require("socket")
<Lua table at 0x22ccef0>

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