Avoid division by zero on small windows#214
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edgar-bonet wants to merge 2 commits intotenox7:masterfrom
Open
Avoid division by zero on small windows#214edgar-bonet wants to merge 2 commits intotenox7:masterfrom
edgar-bonet wants to merge 2 commits intotenox7:masterfrom
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If the window is too small when the program starts, plotwidth stays at
zero. As soon as data arrives, handle_value() computes the appropriate
array index to store it, as
n = (n + 1) % plotwidth;
The division by zero makes the program crash with SIGFPE (Floating-point
exception).
Avoid the crash by initializing plotwidth to the smallest value it can
sensibly have.
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Mar 8, 2026
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@edgar-bonet nice one! I confirm crasher COLUMNS=1 ./ttyplot <<<"1 2 3 4" fixed.
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If the window is too small when the program starts, ttyplot crashes on a division by zero (“Floating-point exception”). This is because
plotwidthnever gets set to a non-zero value, andhandle_value()performs a modulo operation withplotwidthas the denominator.This pull request fixes the crash by initializing
plotwidthwith the minimum value it can sensibly have.