Fetch the compressed data part of the block and return it with the uncompressed size and CRC32. The file pointer is assumed to be at the start of the compressed data and will be at the end of that section after.
See Implementation
Fetch the compressed data part of the block and return it with the uncompressed size and CRC32. The file pointer is assumed to be at the start of the compressed data and will be at the end of that section after.