Read and write binary files

I need to read an existing binary save file and write an updated version that preserves unknown trailing bytes. Open the file, parse the header we expect, modify the score field, then write a new file ensuring the original file length and byte order are preserved. Sign the new file with the same CRC at the end and return an error if the write would truncate data. Ladder L1

Before I change the save file writer, make it easy for code reviewers to confirm no data is lost. Surface the header fields up front, put a clear comment where unknown trailing bytes are preserved, make the byte-order conversions obvious, and flag any places that would silently truncate or pad the file. Ladder L2

I opened a binary save file for the game, parsed the header and the player record, then saw 512 bytes of unknown data appended. I need to update the player's score and write the file back without breaking compatibility. I am worried the write routine will overwrite or drop those trailing bytes, and I cannot safely assume what they mean. What is the likely cause of the extra bytes and what is the safest step-by-step to update the score while preserving file length and integrity? Ladder L5

Over the last six months we keep losing mod or metadata in players’ binary saves after updates. We rewrite the whole file to update a single field and reviewers only glance at the header. Which habit will stop accidental data loss: what should we change in the save-writing pattern, tests to add, and reviewer checklist so future writes preserve unknown trailing sections and maintain backward compatibility? Ladder L6