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fix(big)!: treat uninitialized big.Int as zero #360

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Merged
rvagg merged 1 commit into from
Mar 10, 2025
+23 −14
Merged

fix(big)!: treat uninitialized big.Int as zero #360

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37 changes: 23 additions & 14 deletions big/int.go
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,8 @@ import (
// BigIntMaxSerializedLen is the max length of a byte slice representing a CBOR serialized big.
const BigIntMaxSerializedLen = 128

var zeroInternal = big.NewInt(0)

type Int struct {
*big.Int
}
Expand Down Expand Up @@ -71,19 +73,19 @@ func Product(ints ...Int) Int {
}

func Mul(a, b Int) Int {
return Int{big.NewInt(0).Mul(a.Int, b.Int)}
return Int{big.NewInt(0).Mul(a.i(), b.i())}
}

func Div(a, b Int) Int {
return Int{big.NewInt(0).Div(a.Int, b.Int)}
return Int{big.NewInt(0).Div(a.i(), b.i())}
}

func Mod(a, b Int) Int {
return Int{big.NewInt(0).Mod(a.Int, b.Int)}
return Int{big.NewInt(0).Mod(a.i(), b.i())}
}

func Add(a, b Int) Int {
return Int{big.NewInt(0).Add(a.Int, b.Int)}
return Int{big.NewInt(0).Add(a.i(), b.i())}
}

func Sum(ints ...Int) Int {
Expand All @@ -103,32 +105,32 @@ func Subtract(num1 Int, ints ...Int) Int {
}

func Sub(a, b Int) Int {
return Int{big.NewInt(0).Sub(a.Int, b.Int)}
return Int{big.NewInt(0).Sub(a.i(), b.i())}
}

// Returns a**e unless e <= 0 (in which case returns 1).
func Exp(a Int, e Int) Int {
return Int{big.NewInt(0).Exp(a.Int, e.Int, nil)}
return Int{big.NewInt(0).Exp(a.i(), e.i(), nil)}
}

// Returns x << n
func Lsh(a Int, n uint) Int {
return Int{big.NewInt(0).Lsh(a.Int, n)}
return Int{big.NewInt(0).Lsh(a.i(), n)}
}

// Returns x >> n
func Rsh(a Int, n uint) Int {
return Int{big.NewInt(0).Rsh(a.Int, n)}
return Int{big.NewInt(0).Rsh(a.i(), n)}
}

func BitLen(a Int) uint {
return uint(a.Int.BitLen())
return uint(a.i().BitLen())
}

func Max(x, y Int) Int {
// taken from max.Max()
if x.Equals(Zero()) && x.Equals(y) {
if x.Sign() != 0 {
if x.i().Sign() != 0 {
return y
}
return x
Expand All @@ -142,7 +144,7 @@ func Max(x, y Int) Int {
func Min(x, y Int) Int {
// taken from max.Min()
if x.Equals(Zero()) && x.Equals(y) {
if x.Sign() != 0 {
if x.i().Sign() != 0 {
return x
}
return y
Expand All @@ -154,7 +156,14 @@ func Min(x, y Int) Int {
}

func Cmp(a, b Int) int {
return a.Int.Cmp(b.Int)
return a.i().Cmp(b.i())
}

func (bi Int) i() *big.Int {
if bi.Int != nil {
return bi.Int
}
return zeroInternal
}

// LessThan returns true if bi < o
Expand All @@ -179,7 +188,7 @@ func (bi Int) GreaterThanEqual(o Int) bool {

// Neg returns the negative of bi.
func (bi Int) Neg() Int {
return Int{big.NewInt(0).Neg(bi.Int)}
return Int{big.NewInt(0).Neg(bi.i())}
}

// Abs returns the absolute value of bi.
Expand Down Expand Up @@ -338,7 +347,7 @@ func (bi *Int) UnmarshalCBOR(br io.Reader) error {
}

func (bi *Int) IsZero() bool {
return bi.Int.Sign() == 0
return bi.NilOrZero()
}

func (bi *Int) Nil() bool {
Expand Down