Merge pull request #423 from cosmos/context-GetOp-never-crashes

Context get op never crashes

types/context.go

@@ -186,7 +186,7 @@ func (c Context) WithTxBytes(txBytes []byte) Context {
 //----------------------------------------
 // thePast
 
-// Returns false if ver > 0.
+// Returns false if ver <= 0 || ver > len(c.pst.ops).
 // The first operation is version 1.
 func (c Context) GetOp(ver int64) (Op, bool) {
 	return c.pst.getOp(ver)
@@ -232,13 +232,13 @@ func (pst *thePast) version() int {
 	return pst.ver
 }
 
-// Returns false if ver > 0.
+// Returns false if ver <= 0 || ver > len(pst.ops).
 // The first operation is version 1.
 func (pst *thePast) getOp(ver int64) (Op, bool) {
 	pst.mtx.RLock()
 	defer pst.mtx.RUnlock()
 	l := int64(len(pst.ops))
-	if l < ver {
+	if l < ver || ver <= 0 {
 		return Op{}, false
 	} else {
 		return pst.ops[ver-1], true

types/context_test.go

@@ -0,0 +1,20 @@
+package types_test
+
+import (
+	"testing"
+
+	"github.com/cosmos/cosmos-sdk/types"
+	abci "github.com/tendermint/abci/types"
+)
+
+func TestContextGetOpShouldNeverPanic(t *testing.T) {
+	var ms types.MultiStore
+	ctx := types.NewContext(ms, abci.Header{}, false, nil)
+	indices := []int64{
+		-10, 1, 0, 10, 20,
+	}
+
+	for _, index := range indices {
+		_, _ = ctx.GetOp(index)
+	}
+}