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fix integer overflow in indexOfPosLinear when needle.len > haystack.len

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Techatrix 2024-02-25 12:07:12 +01:00
parent 88b3c14426
commit 9727931fda
1 changed files with 21 additions and 0 deletions
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21
lib/std/mem.zig
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@ -1346,6 +1346,7 @@ pub fn lastIndexOfLinear(comptime T: type, haystack: []const T, needle: []const
/// Consider using `indexOfPos` instead of this, which will automatically use a
/// more sophisticated algorithm on larger inputs.
pub fn indexOfPosLinear(comptime T: type, haystack: []const T, start_index: usize, needle: []const T) ?usize {
if (needle.len > haystack.len) return null;
var i: usize = start_index;
const end = haystack.len - needle.len;
while (i <= end) : (i += 1) {
@ -1354,6 +1355,26 @@ pub fn indexOfPosLinear(comptime T: type, haystack: []const T, start_index: usiz
return null;
}
test indexOfPosLinear {
try testing.expectEqual(0, indexOfPosLinear(u8, "", 0, ""));
try testing.expectEqual(0, indexOfPosLinear(u8, "123", 0, ""));
try testing.expectEqual(null, indexOfPosLinear(u8, "", 0, "1"));
try testing.expectEqual(0, indexOfPosLinear(u8, "1", 0, "1"));
try testing.expectEqual(null, indexOfPosLinear(u8, "2", 0, "1"));
try testing.expectEqual(1, indexOfPosLinear(u8, "21", 0, "1"));
try testing.expectEqual(null, indexOfPosLinear(u8, "222", 0, "1"));
try testing.expectEqual(null, indexOfPosLinear(u8, "", 0, "12"));
try testing.expectEqual(null, indexOfPosLinear(u8, "1", 0, "12"));
try testing.expectEqual(null, indexOfPosLinear(u8, "2", 0, "12"));
try testing.expectEqual(0, indexOfPosLinear(u8, "12", 0, "12"));
try testing.expectEqual(null, indexOfPosLinear(u8, "21", 0, "12"));
try testing.expectEqual(1, indexOfPosLinear(u8, "212", 0, "12"));
try testing.expectEqual(0, indexOfPosLinear(u8, "122", 0, "12"));
try testing.expectEqual(1, indexOfPosLinear(u8, "212112", 0, "12"));
}
fn boyerMooreHorspoolPreprocessReverse(pattern: []const u8, table: *[256]usize) void {
for (table) |*c| {
c.* = pattern.len;