add new standard library value for revertibleRandom

runtime/stdlib/builtin.go

@@ -40,6 +40,7 @@ func DefaultStandardLibraryValues(handler StandardLibraryHandler) []StandardLibr
 		SignatureAlgorithmConstructor,
 		RLPContract,
 		NewLogFunction(handler),
+		NewRevertibleRandomFunction(handler),
 		NewUnsafeRandomFunction(handler),
 		NewGetBlockFunction(handler),
 		NewGetCurrentBlockFunction(handler),

runtime/stdlib/random.go

@@ -26,15 +26,15 @@ import (
 	"github.com/onflow/cadence/runtime/sema"
 )
 
-const unsafeRandomFunctionDocString = `
+const revertibleRandomFunctionDocString = `
 Returns a pseudo-random number.
 
 NOTE: The use of this function is unsafe if not used correctly.
 
 Follow best practices to prevent security issues when using this function
 `
 
-var unsafeRandomFunctionType = &sema.FunctionType{
+var revertibleRandomFunctionType = &sema.FunctionType{
 	ReturnTypeAnnotation: sema.NewTypeAnnotation(
 		sema.UInt64Type,
 	),
@@ -45,6 +45,36 @@ type RandomGenerator interface {
 	ReadRandom([]byte) error
 }
 
+func NewRevertibleRandomFunction(generator RandomGenerator) StandardLibraryValue {
+	return NewStandardLibraryFunction(
+		"revertibleRandom",
+		revertibleRandomFunctionType,
+		revertibleRandomFunctionDocString,
+		func(invocation interpreter.Invocation) interpreter.Value {
+			return interpreter.NewUInt64Value(
+				invocation.Interpreter,
+				func() uint64 {
+					var buffer [8]byte
+					var err error
+					errors.WrapPanic(func() {
+						err = generator.ReadRandom(buffer[:])
+					})
+					if err != nil {
+						panic(interpreter.WrappedExternalError(err))
+					}
+					return binary.LittleEndian.Uint64(buffer[:])
+				},
+			)
+		},
+	)
+}
+
+// `unsafeRandom` related constants and functions will be deleted
+// when the function is deprecated
+const unsafeRandomFunctionDocString = revertibleRandomFunctionDocString
+
+var unsafeRandomFunctionType = revertibleRandomFunctionType
+
 func NewUnsafeRandomFunction(generator RandomGenerator) StandardLibraryValue {
 	return NewStandardLibraryFunction(
 		"unsafeRandom",