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fix: decrement types.Dec max length to keep decimal bits in DecimalPr…
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…ecisionBits (backport cosmos#11772) (cosmos#11805)
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@mergify @Eengineer1
mergify[bot] authored and Eengineer1 committed Aug 26, 2022
1 parent a46730b commit d499799
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Showing 3 changed files with 35 additions and 15 deletions.
4 changes: 4 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,10 @@ Ref: https://keepachangelog.com/en/1.0.0/

## [Unreleased]

### Bug Fixes

* [\#11772](https://github.com/cosmos/cosmos-sdk/pull/11772) Limit types.Dec length to avoid overflow.

## [v0.45.4](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.45.4) - 2022-04-25

### Bug Fixes
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11 changes: 8 additions & 3 deletions math/dec.go
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Original file line number Diff line number Diff line change
Expand Up @@ -22,11 +22,16 @@ const (
// number of decimal places
Precision = 18

// bytes required to represent the above precision
// Ceiling[Log2[999 999 999 999 999 999]]
// bits required to represent the above precision
// Ceiling[Log2[10^Precision - 1]]
DecimalPrecisionBits = 60

maxDecBitLen = maxBitLen + DecimalPrecisionBits
// decimalTruncateBits is the minimum number of bits removed
// by a truncate operation. It is equal to
// Floor[Log2[10^Precision - 1]].
decimalTruncateBits = DecimalPrecisionBits - 1

maxDecBitLen = maxBitLen + decimalTruncateBits

// max number of iterations in ApproxRoot function
maxApproxRootIterations = 100
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35 changes: 23 additions & 12 deletions types/decimal_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ import (
"encoding/json"
"fmt"
"math/big"
"strings"
"testing"

"github.com/stretchr/testify/suite"
Expand Down Expand Up @@ -33,10 +34,10 @@ func (s *decimalTestSuite) TestNewDecFromStr() {
largeBigInt, ok := new(big.Int).SetString("3144605511029693144278234343371835", 10)
s.Require().True(ok)

largerBigInt, ok := new(big.Int).SetString("88888888888888888888888888888888888888888888888888888888888888888888844444440", 10)
largerBigInt, ok := new(big.Int).SetString("8888888888888888888888888888888888888888888888888888888888888888888844444440", 10)
s.Require().True(ok)

largestBigInt, ok := new(big.Int).SetString("133499189745056880149688856635597007162669032647290798121690100488888732861290034376435130433535", 10)
largestBigInt, ok := new(big.Int).SetString("33499189745056880149688856635597007162669032647290798121690100488888732861290034376435130433535", 10)
s.Require().True(ok)

tests := []struct {
Expand All @@ -63,8 +64,8 @@ func (s *decimalTestSuite) TestNewDecFromStr() {
{"foobar", true, sdk.Dec{}},
{"0.foobar", true, sdk.Dec{}},
{"0.foobar.", true, sdk.Dec{}},
{"88888888888888888888888888888888888888888888888888888888888888888888844444440", false, sdk.NewDecFromBigInt(largerBigInt)},
{"133499189745056880149688856635597007162669032647290798121690100488888732861290.034376435130433535", false, sdk.NewDecFromBigIntWithPrec(largestBigInt, 18)},
{"8888888888888888888888888888888888888888888888888888888888888888888844444440", false, sdk.NewDecFromBigInt(largerBigInt)},
{"33499189745056880149688856635597007162669032647290798121690100488888732861290.034376435130433535", false, sdk.NewDecFromBigIntWithPrec(largestBigInt, 18)},
{"133499189745056880149688856635597007162669032647290798121690100488888732861291", true, sdk.Dec{}},
}

Expand Down Expand Up @@ -449,10 +450,14 @@ func (s *decimalTestSuite) TestDecSortableBytes() {
}

func (s *decimalTestSuite) TestDecEncoding() {
largestBigInt, ok := new(big.Int).SetString("133499189745056880149688856635597007162669032647290798121690100488888732861290034376435130433535", 10)
largestBigInt, ok := new(big.Int).SetString("33499189745056880149688856635597007162669032647290798121690100488888732861290034376435130433535", 10)
s.Require().True(ok)

smallestBigInt, ok := new(big.Int).SetString("-133499189745056880149688856635597007162669032647290798121690100488888732861290034376435130433535", 10)
smallestBigInt, ok := new(big.Int).SetString("-33499189745056880149688856635597007162669032647290798121690100488888732861290034376435130433535", 10)
s.Require().True(ok)

const maxDecBitLen = 315
maxInt, ok := new(big.Int).SetString(strings.Repeat("1", maxDecBitLen), 2)
s.Require().True(ok)

testCases := []struct {
Expand Down Expand Up @@ -492,15 +497,21 @@ func (s *decimalTestSuite) TestDecEncoding() {
},
{
sdk.NewDecFromBigIntWithPrec(largestBigInt, 18),
"313333343939313839373435303536383830313439363838383536363335353937303037313632363639303332363437323930373938313231363930313030343838383838373332383631323930303334333736343335313330343333353335",
"\"133499189745056880149688856635597007162669032647290798121690100488888732861290.034376435130433535\"",
"\"133499189745056880149688856635597007162669032647290798121690100488888732861290.034376435130433535\"\n",
"3333343939313839373435303536383830313439363838383536363335353937303037313632363639303332363437323930373938313231363930313030343838383838373332383631323930303334333736343335313330343333353335",
"\"33499189745056880149688856635597007162669032647290798121690100488888732861290.034376435130433535\"",
"\"33499189745056880149688856635597007162669032647290798121690100488888732861290.034376435130433535\"\n",
},
{
sdk.NewDecFromBigIntWithPrec(smallestBigInt, 18),
"2D313333343939313839373435303536383830313439363838383536363335353937303037313632363639303332363437323930373938313231363930313030343838383838373332383631323930303334333736343335313330343333353335",
"\"-133499189745056880149688856635597007162669032647290798121690100488888732861290.034376435130433535\"",
"\"-133499189745056880149688856635597007162669032647290798121690100488888732861290.034376435130433535\"\n",
"2D3333343939313839373435303536383830313439363838383536363335353937303037313632363639303332363437323930373938313231363930313030343838383838373332383631323930303334333736343335313330343333353335",
"\"-33499189745056880149688856635597007162669032647290798121690100488888732861290.034376435130433535\"",
"\"-33499189745056880149688856635597007162669032647290798121690100488888732861290.034376435130433535\"\n",
},
{
sdk.NewDecFromBigIntWithPrec(maxInt, 18),
"3636373439353934383732353238343430303734383434343238333137373938353033353831333334353136333233363435333939303630383435303530323434343434333636343330363435303137313838323137353635323136373637",
"\"66749594872528440074844428317798503581334516323645399060845050244444366430645.017188217565216767\"",
"\"66749594872528440074844428317798503581334516323645399060845050244444366430645.017188217565216767\"\n",
},
}

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