Function asdf_block_data_alloc 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn asdf_block_data_alloc(
    block: *mut AsdfBlock,
    size: usize,
) -> *mut c_void

Allocate a writable buffer of size bytes owned by the block.

An existing owned buffer of exactly size bytes is returned as-is rather than reallocated, so asdf_block_create(NULL, n) followed by this call yields the same buffer.

Safety

block must be null or a valid handle. The returned pointer is valid until the block is destroyed or its data replaced.