Transferring ownership of an IOBuf to another data structure with as few memcpy as possible

[ardieb]

I need to transfer ownership back and forth between a immutable data container and IOBuf. The container maintains contiguous segments of memory allocated using std::malloc. The data structure has a method reset that takes ownership of the provided uint8_t pointer and the given length of memory. I've tried the following code, which causes a segfault. The IOBuf is not chained and is stored in a unique_ptr. Is there a standard way of releasing ownership of the underlying data in IOBuf?

buffer->unshare();
MyBuffer payload;
payload.reset(buffer->writableData(), buffer->length());
buffer->markExternallyShared();

[afrind]

I'm not sure you can get IOBuf to release its underlying buffer, but you can construct one wrapping a buffer that you own (so it won't delete it at destruction time). See IOBuf::wrapBuffer.