Implement tail -n for a Very Large File

Design and implement the core of tail -n: given a seekable file and a non-negative integer n, return the final n logical lines without reading the entire file when the requested suffix is small.

The file may be many gigabytes. Explain binary-versus-text handling, newline semantics, chunk boundaries, decoding, and complexity. You may first solve for bytes with \n as the delimiter, then explain how decoded text is produced safely.

Constraints & Assumptions

• The file is seekable and its size can be queried.
• Reads should occur in bounded chunks from the end toward the beginning.
• A file may be empty or may end with or without a newline.
• n == 0 returns an empty result.

Clarifying Questions to Ask

• Does a trailing newline create an additional empty logical line?
• Which encoding is used, and how should invalid byte sequences be handled?
• Must output preserve exact line-ending bytes?
• Can the file change while it is being read?