Allocates a block of memory from the slice allocator and copies @block_size bytes into it from @mem_block.
@mem_block must be non-%NULL if @block_size is non-zero.
the number of bytes to allocate
the memory to copy
a pointer to the allocated memory block, which will be %NULL if and only if @mem_size is 0
2.14
See Implementation
Allocates a block of memory from the slice allocator and copies @block_size bytes into it from @mem_block.
@mem_block must be non-%NULL if @block_size is non-zero.