terminal: Prevent scrollbar arithmetic underflow panic#45282
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P1n3appl3 merged 2 commits intozed-industries:mainfrom Dec 19, 2025
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Standardize all subtraction operations in terminal_scrollbar.rs to use `saturating_sub` instead of raw subtraction or `checked_sub().unwrap_or(0)`. This prevents panics when `total_lines < viewport_lines + display_offset`, which can occur during terminal creation, small window sizes, or when display_offset becomes stale. Closes zed-industries#45281
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rtfeldman
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Jan 5, 2026
## Summary Fixes arithmetic underflow panics in `terminal_scrollbar.rs` by converting unsafe subtractions to `saturating_sub`. Closes #45281 ## Problem Two locations perform raw subtraction on `usize` values that panic when underflow occurs: - `offset()`: `state.total_lines - state.viewport_lines - state.display_offset` - `set_offset()`: `state.total_lines - state.viewport_lines` This happens when `total_lines < viewport_lines + display_offset`, which can occur during terminal creation, with small window sizes, or when display state becomes stale. ## Solution Replace the two unsafe subtractions with `saturating_sub`, which returns 0 on underflow instead of panicking. Also standardizes the existing `checked_sub().unwrap_or(0)` in `max_offset()` to `saturating_sub` for consistency across the file. ## Changes - N/A
LivioGama
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Jan 20, 2026
…s#45282) ## Summary Fixes arithmetic underflow panics in `terminal_scrollbar.rs` by converting unsafe subtractions to `saturating_sub`. Closes zed-industries#45281 ## Problem Two locations perform raw subtraction on `usize` values that panic when underflow occurs: - `offset()`: `state.total_lines - state.viewport_lines - state.display_offset` - `set_offset()`: `state.total_lines - state.viewport_lines` This happens when `total_lines < viewport_lines + display_offset`, which can occur during terminal creation, with small window sizes, or when display state becomes stale. ## Solution Replace the two unsafe subtractions with `saturating_sub`, which returns 0 on underflow instead of panicking. Also standardizes the existing `checked_sub().unwrap_or(0)` in `max_offset()` to `saturating_sub` for consistency across the file. ## Changes - N/A
LivioGama
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to LivioGama/zed
that referenced
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Jan 20, 2026
…s#45282) ## Summary Fixes arithmetic underflow panics in `terminal_scrollbar.rs` by converting unsafe subtractions to `saturating_sub`. Closes zed-industries#45281 ## Problem Two locations perform raw subtraction on `usize` values that panic when underflow occurs: - `offset()`: `state.total_lines - state.viewport_lines - state.display_offset` - `set_offset()`: `state.total_lines - state.viewport_lines` This happens when `total_lines < viewport_lines + display_offset`, which can occur during terminal creation, with small window sizes, or when display state becomes stale. ## Solution Replace the two unsafe subtractions with `saturating_sub`, which returns 0 on underflow instead of panicking. Also standardizes the existing `checked_sub().unwrap_or(0)` in `max_offset()` to `saturating_sub` for consistency across the file. ## Changes - N/A
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Summary
Fixes arithmetic underflow panics in
terminal_scrollbar.rsby converting unsafe subtractions tosaturating_sub.Closes #45281
Problem
Two locations perform raw subtraction on
usizevalues that panic when underflow occurs:offset():state.total_lines - state.viewport_lines - state.display_offsetset_offset():state.total_lines - state.viewport_linesThis happens when
total_lines < viewport_lines + display_offset, which can occur during terminal creation, with small window sizes, or when display state becomes stale.Solution
Replace the two unsafe subtractions with
saturating_sub, which returns 0 on underflow instead of panicking.Also standardizes the existing
checked_sub().unwrap_or(0)inmax_offset()tosaturating_subfor consistency across the file.Changes
crates/terminal_view/src/terminal_scrollbar.rs: 3 subtraction operations now usesaturating_sub