SIGBUS when viewing a file that is truncated while loading

[tstack]

Description

When opening a file that is then truncated, the program crashes with a SIGBUS.

Platform

MacOS 14.3

tl v1.0.0

How to reproduce

The easiest way is to create a large file with a bunch of lines, run tl bigfile.txt. Then, while tl is scanning for new lines, run truncate -s 0 bigfile.txt in another terminal.

Details

Using mmap() on a file the app doesn't own/control is problematic since changes to the file can mess up your process. It would probably be best to avoid mmap() and use regular file I/O instead.

While this may seem unlikely, it can happen in practice because of things like logrotate's copytruncate option which will copy the file contents and then truncate it.