tools : fix invalid free()

[aumfer]

Added a constructor to server_context that initializes server_context::batch, preventing the destructor's call to llama_batch_free() from causing an invalid free().

Ran into this when bind() failed.

[aumfer]

There are other ways to solve this if you don't want to zero out the entire llama_batch object. (eg track whether server_context::init() has been called, check in the destructor before calling llama_batch_free)

[ngxson]

I think the proper fix is to check if batch.embd is not nullptr before freeing it. This is the same pattern with other _free functions in llama.cpp where we do nothing given a nullptr

[slaren]

Both free and delete will ignore a null pointer, these checks are not necessary. The problem here is uninitialized memory.

[ngxson]

Ok that makes sense. I think this can be the temporary solution before we finally have the private batch API.

[cebtenzzre]

nit: could just use llama_batch batch = {}; in the field declaration on line 1865 to keep the default noexcept constructor.

[aumfer]

I didn't realize you could initialize non-scalar members in that way. I went ahead and updated this PR to use 'direct-list-initialization' as described here: https://en.cppreference.com/w/cpp/language/list_initialization