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Fix InternalScreen bounds checks #284

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Merged
rockorager merged 2 commits into from
Dec 28, 2025
Merged

Fix InternalScreen bounds checks #284

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3138b64
Fix InternalScreen bounds checks
dyxushuai Dec 28, 2025
891a9c9
Use <= in InternalScreen bounds checks
dyxushuai Dec 28, 2025
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22 changes: 18 additions & 4 deletions src/InternalScreen.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -83,11 +83,11 @@ pub fn writeCell(
row: u16,
cell: Cell,
) void {
if (self.width < col) {
if (col >= self.width) {
// column out of bounds
return;
}
if (self.height < row) {
if (row >= self.height) {
// height out of bounds
return;
}
Expand All @@ -110,11 +110,11 @@ pub fn writeCell(
}

pub fn readCell(self: *InternalScreen, col: u16, row: u16) ?Cell {
if (self.width < col) {
if (col >= self.width) {
// column out of bounds
return null;
}
if (self.height < row) {
if (row >= self.height) {
// height out of bounds
return null;
}
Expand All @@ -131,3 +131,17 @@ pub fn readCell(self: *InternalScreen, col: u16, row: u16) ?Cell {
.default = cell.default,
};
}

test "InternalScreen: out-of-bounds read/write are ignored" {
var screen = try InternalScreen.init(std.testing.allocator, 2, 2);
defer screen.deinit(std.testing.allocator);

const sentinel: Cell = .{ .char = .{ .grapheme = "A", .width = 1 } };
screen.writeCell(0, 1, sentinel);

const oob_cell: Cell = .{ .char = .{ .grapheme = "X", .width = 1 } };
screen.writeCell(2, 0, oob_cell);
const read_back = screen.readCell(0, 1) orelse return error.TestUnexpectedResult;
try std.testing.expect(std.mem.eql(u8, read_back.char.grapheme, "A"));
try std.testing.expect(screen.readCell(2, 0) == null);
}