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cluadynamic-library

how to unload dynamic lib in lua

I'm using luajit2.0.4 as lua interpreter. here is the situation:

after I load a dynamic lib like cjson.so with

cjson = require('cjson')
a=cjson.new() -- blahblah... do things i want

then I need to overwrite the lib file, ( a situation of hot upgrade, and here cjson.so_1 and cjson.so might be the same)

[root@localhost lib]# cp cjson.so_1 cjson.so
cp: overwrite `cjson.so'? y

it will force kernel to truncate the physical memory of cjson.so's pmap, and causing a page missing then when I call

a=cjson.new()

again, the kernel will recopy the cjson.so lib into memory, this time not parsing the global symbols. so when I call new() which need to call external functions like malloc(), a segment fault will occur.

I've already found a way to reload by writing a unload funtion in C,

and my question is can I do this by lua code itself?

Solution

  • Sadly, this is not possible.

    You'd have to approach the situation using C/C++, but not using Lua, due to the way in which Lua works, and I wish there would've been a different answer but Lua has got it's limits.