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chore(lib/common) implement MustHexToBigInt #1547

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merged 4 commits into from
Apr 29, 2021
Merged

chore(lib/common) implement MustHexToBigInt #1547

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b26971b
implement MustHexToBigInt
edwardmack Apr 28, 2021
923758e
add tests for panics
edwardmack Apr 29, 2021
ca4c88a
clean-up string checking
edwardmack Apr 29, 2021
bdf66b2
Merge branch 'development' into ed/must_hex_number_to_big_int
edwardmack Apr 29, 2021
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4 changes: 1 addition & 3 deletions dot/import.go
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,6 @@ import (
"encoding/json"
"errors"
"io/ioutil"
"math/big"
"path/filepath"

"github.com/ChainSafe/gossamer/dot/state"
Expand Down Expand Up @@ -97,8 +96,7 @@ func newHeaderFromFile(filename string) (*types.Header, error) {
return nil, errors.New("invalid number field in header JSON")
}

numBytes := common.MustHexToBytes(hexNum)
num := big.NewInt(0).SetBytes(numBytes)
num := common.MustHexToBigInt(hexNum)

parentHashStr, ok := jsonHeader["parentHash"].(string)
if !ok {
Expand Down
26 changes: 26 additions & 0 deletions lib/common/common.go
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@ import (
"encoding/hex"
"errors"
"io"
"math/big"
"strconv"
"strings"
)
Expand Down Expand Up @@ -103,6 +104,31 @@ func MustHexToBytes(in string) []byte {
return out
}

// MustHexToBigInt turns a 0x prefixed hex string into a big.Int
// it panic if it cannot decode the string
func MustHexToBigInt(in string) *big.Int {
if len(in) < 2 {
panic("invalid string")
}

if strings.Compare(in[:2], "0x") != 0 {
panic(ErrNoPrefix)
}

// Ensure we have an even length
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	in = in[2:]

	// Ensure we have an even length
	if len(in)%2 != 0 {
		in = "0" + in
	}

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Yes, this looks better, updated.

if len(in)%2 != 0 {
in = in[:2] + "0" + in[2:]
}

in = in[2:]
out, err := hex.DecodeString(in)
if err != nil {
panic(err)
}

return big.NewInt(0).SetBytes(out)
}

// BytesToHex turns a byte slice into a 0x prefixed hex string
func BytesToHex(in []byte) string {
s := hex.EncodeToString(in)
Expand Down
33 changes: 33 additions & 0 deletions lib/common/common_test.go
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Expand Up @@ -18,8 +18,12 @@ package common

import (
"bytes"
"math/big"
"reflect"
"testing"

"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)

func TestStringToInts(t *testing.T) {
Expand Down Expand Up @@ -182,3 +186,32 @@ func TestSwapNibbles(t *testing.T) {
}
}
}

func TestMustHexToBigInt(t *testing.T) {
tests := []struct {
in string
out *big.Int
}{
{"0x0", big.NewInt(0).SetBytes([]byte{0})},
{"0x00", big.NewInt(0).SetBytes([]byte{0})},
{"0x1", big.NewInt(1)},
{"0x01", big.NewInt(1)},
{"0xf", big.NewInt(15)},
{"0x0f", big.NewInt(15)},
{"0x10", big.NewInt(16)},
{"0xff", big.NewInt(255)},
{"0x50429", big.NewInt(328745)},
{"0x050429", big.NewInt(328745)},
}

for _, test := range tests {
res := MustHexToBigInt(test.in)
require.Equal(t, test.out, res)
}
}

func TestMustHexToBigIntPanic(t *testing.T) {
assert.Panics(t, func() { MustHexToBigInt("1") }, "should panic for string len < 2")
assert.Panics(t, func() { MustHexToBigInt("12") }, "should panic for string not starting with 0x")
assert.Panics(t, func() { MustHexToBigInt("0xzz") }, "should panic for string not containing hex characters")
}