CODEWITHSUNDEEP
luaheap-memory
user2589882
user2589882

Reputation: 69

Heap memory access in lua

Is it possible to access contents of heap memory in Lua by passing it a pointer to memory address allocated by malloc function in C?

I have tried this :

int *j=(int *)malloc(sizeof(int));
j[0]=5;

passing (j as a pointer to Lua), then Lua access contents at memory location pointed by pointer j.

Upvotes: 3

Views: 2409

Answers (2)

tprk77
tprk77

Reputation: 1171

What do you actually want to do? Your question seems to ask about moving data from C to Lua. Your comments suggest that you want to share memory between two separate processes.

If you just want to use some C with Lua, then you should write and extension (and use userdata to move data around). For example, if you have a library written in C and you want to use it in Lua, you will need to extend Lua with a module wrapping the library. This is covered in Part IV of PIL. When using an extension, there is only one process so memory is easily shared between C and Lua.

If you really need to share data between two processes, you will need to find some kind of IPC that works for you. Using a socket is an obvious choice, for that you can use LuaSocket. If you want a pub/sub, then you could try LCM, which supports both C and Lua.

Upvotes: 1

lhf
lhf

Reputation: 72402

There is no built-in support for that.

You can write your own support in C by exporting a version of malloc to Lua that creates memory buffers as userdata and provides suitable metamethods for easy access of the contents. (But use lua_newuserdata instead malloc.)

A few of these have appeared in the Lua mailing list. See for instance

Upvotes: 3

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