AllowOverInt64 in amount.IntStringToAmount (#609)

amount/main.go

@@ -13,6 +13,7 @@ import (
 	"math/big"
 	"regexp"
 	"strconv"
+	"strings"
 
 	"github.com/stellar/go/support/errors"
 	"github.com/stellar/go/xdr"
@@ -32,7 +33,8 @@ var (
 	// to `big.Rat.SetString` triggering long calculations.
 	// Note: {1,20} because the biggest amount you can use in Stellar is:
 	// len("922337203685.4775807") = 20.
-	validAmountSimple = regexp.MustCompile("^-?[.0-9]{1,20}$")
+	validAmountSimple          = regexp.MustCompile("^-?[.0-9]{1,20}$")
+	negativePositiveNumberOnly = regexp.MustCompile("^-?[0-9]+$")
 )
 
 // MustParse is the panicking version of Parse.
@@ -85,18 +87,29 @@ func ParseInt64(v string) (int64, error) {
 // and returns the string representation of that number.
 // It is safe to use with values exceeding int64 limits.
 func IntStringToAmount(v string) (string, error) {
-	if !validAmountSimple.MatchString(v) {
+	if !negativePositiveNumberOnly.MatchString(v) {
 		return "", errors.Errorf("invalid amount format: %s", v)
 	}
 
-	r := &big.Rat{}
-	if _, ok := r.SetString(v); !ok {
-		return "", errors.Errorf("cannot parse amount: %s", v)
+	negative := false
+	if v[0] == '-' {
+		negative = true
+		v = v[1:]
 	}
 
-	r.Quo(r, bigOne)
+	l := len(v)
+	var r string
+	if l <= 7 {
+		r = "0." + strings.Repeat("0", 7-l) + v
+	} else {
+		r = v[0:l-7] + "." + v[l-7:l]
+	}
+
+	if negative {
+		r = "-" + r
+	}
 
-	return r.FloatString(7), nil
+	return r, nil
 }
 
 // String returns an "amount string" from the provided raw xdr.Int64 value `v`.

amount/main_test.go

@@ -87,9 +87,15 @@ func TestIntStringToAmount(t *testing.T) {
 		{"-92233.7203686", "-922337203686", true},
 		{"1000000000000.0000000", "10000000000000000000", true},
 		{"0.0000000", "0", true},
+		// Expensive inputs when using big.Rat:
+		{"10000000000000.0000000", "1" + strings.Repeat("0", 20), true},
+		{"-10000000000000.0000000", "-1" + strings.Repeat("0", 20), true},
+		{"1" + strings.Repeat("0", 1000-7) + ".0000000", "1" + strings.Repeat("0", 1000), true},
+		{"1" + strings.Repeat("0", 1000000-7) + ".0000000", "1" + strings.Repeat("0", 1000000), true},
+		// Invalid inputs
 		{"", "nan", false},
-		// Expensive inputs:
-		{"", strings.Repeat("1", 1000000), false},
+		{"", "", false},
+		{"", "-", false},
 		{"", "1E9223372036854775807", false},
 		{"", "1e9223372036854775807", false},
 		{"", "Inf", false},

services/horizon/internal/actions_assets.go

@@ -71,7 +71,11 @@ func (action *AssetsAction) loadRecords() {
 func (action *AssetsAction) loadPage() {
 	for _, record := range action.Records {
 		var res resource.AssetStat
-		res.Populate(action.Ctx, record)
+		err := res.Populate(action.R.Context(), record)
+		if err != nil {
+			action.Err = err
+			return
+		}
 		action.Page.Add(res)
 	}
 

services/horizon/internal/resource/asset_stat.go

@@ -6,6 +6,7 @@ import (
 	"github.com/stellar/go/amount"
 	"github.com/stellar/go/services/horizon/internal/db2/assets"
 	"github.com/stellar/go/services/horizon/internal/render/hal"
+	"github.com/stellar/go/support/errors"
 	"github.com/stellar/go/xdr"
 )
 
@@ -14,13 +15,12 @@ func (res *AssetStat) Populate(
 	ctx context.Context,
 	row assets.AssetStatsR,
 ) (err error) {
-
 	res.Asset.Type = row.Type
 	res.Asset.Code = row.Code
 	res.Asset.Issuer = row.Issuer
 	res.Amount, err = amount.IntStringToAmount(row.Amount)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "Invalid amount in PopulateAssetStat")
 	}
 	res.NumAccounts = row.NumAccounts
 	res.Flags = AccountFlags{

services/horizon/internal/resource/asset_stat_test.go

@@ -0,0 +1,32 @@
+package resource
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stellar/go/services/horizon/internal/db2/assets"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestLargeAmount(t *testing.T) {
+	row := assets.AssetStatsR{
+		SortKey:     "",
+		Type:        "credit_alphanum4",
+		Code:        "XIM",
+		Issuer:      "GBZ35ZJRIKJGYH5PBKLKOZ5L6EXCNTO7BKIL7DAVVDFQ2ODJEEHHJXIM",
+		Amount:      "100000000000000000000", // 10T
+		NumAccounts: 429,
+		Flags:       0,
+		Toml:        "https://xim.com/.well-known/stellar.toml",
+	}
+	var res AssetStat
+	err := res.Populate(context.Background(), row)
+	assert.NoError(t, err)
+
+	assert.Equal(t, "credit_alphanum4", res.Type)
+	assert.Equal(t, "XIM", res.Code)
+	assert.Equal(t, "GBZ35ZJRIKJGYH5PBKLKOZ5L6EXCNTO7BKIL7DAVVDFQ2ODJEEHHJXIM", res.Issuer)
+	assert.Equal(t, "10000000000000.0000000", res.Amount)
+	assert.Equal(t, int32(429), res.NumAccounts)
+	assert.Equal(t, "https://xim.com/.well-known/stellar.toml", res.Links.Toml.Href)
+}