8000 Fix `Uint256::increment` panics by TheBlueMatt · Pull Request #612 · rust-bitcoin/rust-bitcoin · GitHub
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Fix Uint256::increment panics #612

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Merged
merged 4 commits into from
Sep 27, 2021
Merged

Fix Uint256::increment panics #612

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d52b88b
Fix increment of Uint256 with carry
carolcapps Mar 13, 2021
a15f263
Move the `increment` fn into the uint macro to add it to Uint128
TheBlueMatt Jun 8, 2021
9c256cc
Add a fuzz check for `Uint128::increment`
TheBlueMatt Jun 8, 2021
5d71a9d
Correct input length check for uin128 fuzzer
TheBlueMatt Jun 15, 2021
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6 changes: 5 additions & 1 deletion fuzz/fuzz_targets/uint128_fuzz.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@ fn do_test(data: &[u8]) {
} }
}

if data.len() != 16*2 + 1 { return; }
if data.len() != 16*2 { return; }
let (a_native, a) = read_ints!(0);

// Checks using only a:
Expand All @@ -40,6 +40,10 @@ fn do_test(data: &[u8]) {
assert_eq!(128 - a_native.leading_zeros() as usize, a.bits());
assert_eq!(a_native as u64, bitcoin::util::uint::Uint128::from_u64(a_native as u64).unwrap().low_u64());

let mut a_inc = a.clone();
a_inc.increment();
check_eq!(a_native.wrapping_add(1), a_inc);

// Checks with two numbers:
let (b_native, b) = read_ints!(16);

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73 changes: 57 additions & 16 deletions src/util/uint.rs
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8000 8A1C
Original file line number Diff line number Diff line change
Expand Up @@ -162,6 +162,16 @@ macro_rules! construct_uint {

($name(ret), sub_copy)
}

/// Increment by 1
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I think we need to explain in the doc that the function does wrapping increment

#[inline]
pub fn increment(&mut self) {
let &mut $name(ref mut arr) = self;
for i in 0..$n_words {
arr[i] = arr[i].wrapping_add(1);
if arr[i] != 0 { break; }
}
}
}

impl PartialOrd for $name {
Expand Down Expand Up @@ -512,22 +522,6 @@ impl ::std::fmt::Display for ParseLengthError {
impl ::std::error::Error for ParseLengthError {}

impl Uint256 {
/// Increment by 1
#[inline]
pub fn increment(&mut self) {
let &mut Uint256(ref mut arr) = self;
arr[0] += 1;
if arr[0] == 0 {
arr[1] += 1;
if arr[1] == 0 {
arr[2] += 1;
if arr[2] == 0 {
arr[3] += 1;
}
}
}
}

/// Decay to a uint128
#[inline]
pub fn low_128(&self) -> Uint128 {
Expand Down Expand Up @@ -689,6 +683,53 @@ mod tests {
0x4AFCFF6F0375C608u64, 0x928D92B4D7F5DF33u64]));
}

#[test]
pub fn increment_test() {
let mut val = Uint256([
0xFFFFFFFFFFFFFFFEu64,
0xFFFFFFFFFFFFFFFFu64,
0xFFFFFFFFFFFFFFFFu64,
0xEFFFFFFFFFFFFFFFu64,
]);
val.increment();
assert_eq!(
val,
Uint256([
0xFFFFFFFFFFFFFFFFu64,
0xFFFFFFFFFFFFFFFFu64,
0xFFFFFFFFFFFFFFFFu64,
0xEFFFFFFFFFFFFFFFu64,
])
);
val.increment();
assert_eq!(
val,
Uint256([
0x0000000000000000u64,
0x0000000000000000u64,
0x0000000000000000u64,
0xF000000000000000u64,
])
);

let mut val = Uint256([
0xFFFFFFFFFFFFFFFFu64,
0xFFFFFFFFFFFFFFFFu64,
0xFFFFFFFFFFFFFFFFu64,
0xFFFFFFFFFFFFFFFFu64,
]);
val.increment();
assert_eq!(
val,
Uint256([
0x0000000000000000u64,
0x0000000000000000u64,
0x0000000000000000u64,
0x0000000000000000u64,
])
);
}

#[test]
pub fn uint256_bitslice_test() {
let init = Uint256::from_u64(0xDEADBEEFDEADBEEF).unwrap();
Expand Down
0