[#42] common: Add routines for fixed-width uint64 marshaling

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>
This commit is contained in:
Evgenii Stratonikov 2023-10-05 13:53:12 +03:00 committed by Alex Vanin
parent ab0a899a28
commit 2be81b1def
4 changed files with 96 additions and 0 deletions

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@ -1,6 +1,7 @@
package common
import (
"github.com/nspcc-dev/neo-go/pkg/interop/convert"
"github.com/nspcc-dev/neo-go/pkg/interop/native/std"
"github.com/nspcc-dev/neo-go/pkg/interop/storage"
)
@ -10,3 +11,18 @@ func SetSerialized(ctx storage.Context, key interface{}, value interface{}) {
data := std.Serialize(value)
storage.Put(ctx, key, data)
}
// ToFixedWidth64 converts x to bytes such that numbers <= math.MaxUint64
// have constant with of 9.
func ToFixedWidth64(x int) []byte {
data := convert.ToBytes(x)
if x < 0 || len(data) >= 9 {
return data
}
return append(data, make([]byte, 9-len(data))...)
}
// FromFixedWidth64 is a reverse function for ToFixedWidth64.
func FromFixedWidth64(x []byte) int {
return convert.ToInteger(x)
}

61
tests/common_test.go Normal file
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@ -0,0 +1,61 @@
package tests
import (
"math"
"math/big"
"path"
"testing"
"github.com/nspcc-dev/neo-go/pkg/neotest"
"github.com/stretchr/testify/require"
)
const testdataPath = "./testdata"
func newTestdataInvoker(t *testing.T) *neotest.ContractInvoker {
e := newExecutor(t)
ctr := neotest.CompileFile(t, e.CommitteeHash, testdataPath, path.Join(testdataPath, "config.yml"))
e.DeployContract(t, ctr, nil)
return e.CommitteeInvoker(ctr.Hash)
}
func TestEncodeU64(t *testing.T) {
// Let's check boundary values for all bit sizes:
var nums []uint64
for i := 0; i < 64; i++ {
if i != 0 {
nums = append(nums, (1<<i)-1)
}
nums = append(nums, 1<<i)
if i != 63 {
nums = append(nums, (1<<i)+1)
}
}
c := newTestdataInvoker(t)
for _, n := range nums {
v, err := c.TestInvoke(t, "encode", n)
require.NoError(t, err)
require.Equal(t, 1, v.Len())
r := v.Pop().Bytes()
require.Equal(t, 9, len(r), "got: %x", r)
v, err = c.TestInvoke(t, "encodeDecode", n)
require.NoError(t, err)
require.Equal(t, 1, v.Len())
require.Equal(t, n, v.Pop().BigInt().Uint64())
}
t.Run("bad cases should be handled", func(t *testing.T) {
x := new(big.Int).SetUint64(math.MaxUint64)
x.Add(x, big.NewInt(1))
nums := []*big.Int{x, big.NewInt(-1), big.NewInt(-128)}
for _, n := range nums {
v, err := c.TestInvoke(t, "encodeDecode", n)
require.NoError(t, err)
require.Equal(t, 0, v.Pop().BigInt().Cmp(n))
}
})
}

2
tests/testdata/config.yml vendored Normal file
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@ -0,0 +1,2 @@
name: "TestContract"
safemethods: ["encodeDecode"]

17
tests/testdata/encode.go vendored Normal file
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@ -0,0 +1,17 @@
package testdata
import (
"git.frostfs.info/TrueCloudLab/frostfs-contract/common"
)
// EncodeDecode encodes x in fixed-width little-endian representation
// and deserializes it back.
func EncodeDecode(x int) int {
y := common.ToFixedWidth64(x)
return common.FromFixedWidth64(y)
}
// Encode encodes x in fixed-width little-endian representation.
func Encode(x int) []byte {
return common.ToFixedWidth64(x)
}