Copy available bytes to the specified buffer but keep them available. The underlying implementation could trigger bytes population from the underlying source and block until any bytes available.
Try to copy at least min but up to max bytes to the specified destination buffer from this input skipping offset bytes. If there are not enough bytes available to provide min bytes after skipping offset bytes then it will trigger the underlying source reading first and after that will simply copy available bytes even if EOF encountered so min is not a requirement but a desired number of bytes. It is safe to specify max greater than the destination free space.
min shouldn't be bigger than the destination free space. This function could trigger the underlying source reading that may lead to blocking I/O. It is allowed to specify too big offset so in this case this function will always return
0 after prefetching all underlying bytes but note that it may lead to significant memory consumption. This function usually copy more bytes than min (unless
max = min) but it is not guaranteed. When
0 is returned with
offset = 0 then it makes sense to check endOfInput.