Fixing a 20-year-old bug in Enlightenment E16

The author, a daily user of the 1997 Enlightenment E16 window manager, describes the intricate process of resolving a critical, decades-old bug. This bug, which caused a deterministic freeze when opening a specific PDF, ultimately stemmed from a flawed implementation of Newton's algorithm.

• Enlightenment E16, created in 1997, is celebrated for being themable, hackable, and lightweight (peaking at 24MB RSS), maintaining a dedicated enthusiast community.
• The bug manifested as a system freeze traced to imlib2's font cache, with GDB showing an oscillation in the TextstateTextFitMB function, responsible for truncating long window titles.
• The core issue was a Newton-style search algorithm lacking iteration limits, causing it to endlessly oscillate between two trial truncations rather than converging or terminating.
• The fix involved implementing defensive measures: capping iteration counts at 32, flooring nuke_count at 1 to prevent degenerate string states, and flooring cw (average pixels per char) at 1 to avoid division by zero.
• The bug was reproducible with any window whose WM_NAME was long enough to trigger the truncation algorithm's overshoot regime, such as "Kickoff.pdf — Introduction to Information Theory Session 1: kickoff & first topic".
• The author also includes a philosophical reflection, arguing that newer software isn't always better, citing recent kernel bugs and the XZ backdoor as examples of modern vulnerabilities, and praising the stability and self-reliance of maintaining older software.

This story highlights a fascinating intersection of software archeology, robust debugging, and contemporary concerns about software integrity and the "supply chain" of modern systems. It's a testament to the longevity of well-designed, if sometimes imperfect, open-source projects.