| 28 | } |
| 29 | |
| 30 | func opCheckPredicate(vm *virtualMachine) error { |
| 31 | err := vm.applyCost(256) |
| 32 | if err != nil { |
| 33 | return err |
| 34 | } |
| 35 | vm.deferCost(-256 + 64) // get most of that cost back at the end |
| 36 | limit, err := vm.popInt64(true) |
| 37 | if err != nil { |
| 38 | return err |
| 39 | } |
| 40 | predicate, err := vm.pop(true) |
| 41 | if err != nil { |
| 42 | return err |
| 43 | } |
| 44 | n, err := vm.popInt64(true) |
| 45 | if err != nil { |
| 46 | return err |
| 47 | } |
| 48 | if limit < 0 { |
| 49 | return ErrBadValue |
| 50 | } |
| 51 | l := int64(len(vm.dataStack)) |
| 52 | if n > l { |
| 53 | return ErrDataStackUnderflow |
| 54 | } |
| 55 | if limit == 0 { |
| 56 | limit = vm.runLimit |
| 57 | } |
| 58 | err = vm.applyCost(limit) |
| 59 | if err != nil { |
| 60 | return err |
| 61 | } |
| 62 | |
| 63 | childVM := virtualMachine{ |
| 64 | context: vm.context, |
| 65 | program: predicate, |
| 66 | runLimit: limit, |
| 67 | depth: vm.depth + 1, |
| 68 | dataStack: append([][]byte{}, vm.dataStack[l-n:]...), |
| 69 | } |
| 70 | vm.dataStack = vm.dataStack[:l-n] |
| 71 | |
| 72 | childErr := childVM.run() |
| 73 | |
| 74 | vm.deferCost(-childVM.runLimit) |
| 75 | vm.deferCost(-stackCost(childVM.dataStack)) |
| 76 | vm.deferCost(-stackCost(childVM.altStack)) |
| 77 | |
| 78 | return vm.pushBool(childErr == nil && !childVM.falseResult(), true) |
| 79 | } |
| 80 | |
| 81 | func opJump(vm *virtualMachine) error { |
| 82 | err := vm.applyCost(1) |