rust-bitcoin-unsafe-fast/src/blockdata/script.rs

// Rust Bitcoin Library
// Written in 2014 by
//   Andrew Poelstra <apoelstra@wpsoftware.net>
//
// To the extent possible under law, the author(s) have dedicated all
// copyright and related and neighboring rights to this software to
// the public domain worldwide. This software is distributed without
// any warranty.
//
// You should have received a copy of the CC0 Public Domain Dedication
// along with this software.
// If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
//

//! # Script
//!
//! Scripts define Bitcoin's digital signature scheme: a signature is formed
//! from a script (the second half of which is defined by a coin to be spent,
//! and the first half provided by the spending transaction), and is valid
//! iff the script leaves `TRUE` on the stack after being evaluated.
//! Bitcoin's script is a stack-based assembly language similar in spirit to
//! Forth.
//!
//! This module provides the structures and functions needed to support scripts.
//!

use std::hash;
use std::char::from_digit;
use std::default::Default;
use std::ops;
use serialize::json;
use serialize::hex::ToHex;

use crypto::digest::Digest;
use crypto::ripemd160::Ripemd160;
use crypto::sha1::Sha1;
use crypto::sha2::Sha256;
use secp256k1::Secp256k1;
use secp256k1::key::PublicKey;
use serde;

use blockdata::opcodes;
use blockdata::transaction::{Transaction, TxIn};
use network::encodable::{ConsensusDecodable, ConsensusEncodable};
use network::serialize::{SimpleDecoder, SimpleEncoder, serialize};
use util::hash::Sha256dHash;
use util::misc::script_find_and_remove;

#[derive(PartialEq, Eq, Debug, Clone)]
/// A Bitcoin script
pub struct Script(Box<[u8]>);

impl hash::Hash for Script {
  #[inline]
  fn hash<H>(&self, state: &mut H)
    where H: hash::Hasher
  {
    let &Script(ref raw) = self;
    (&raw[..]).hash(state);
  }

  #[inline]
  fn hash_slice<H>(data: &[Script], state: &mut H)
    where H: hash::Hasher
  {
    for s in data.iter() {
      let &Script(ref raw) = s;
      (&raw[..]).hash(state);
    }
  }
}

/// Ways that a script might fail. Not everything is split up as
/// much as it could be; patches welcome if more detailed errors
/// would help you.
#[derive(PartialEq, Eq, Debug, Clone)]
pub enum Error {
  /// The script returns false no matter the input
  AnalyzeAlwaysReturnsFalse,
  /// Tried to set a boolean to both values, but neither worked
  AnalyzeNeitherBoolWorks,
  /// Tried to set a boolean to the given value, but it already
  /// had the other value
  AnalyzeSetBoolMismatch(bool),
  /// Validation of an element failed
  AnalyzeValidateFailed,
  /// OP_CHECKSIG was called with a bad public key
  BadPublicKey,
  /// OP_CHECKSIG was called with a bad signature
  BadSignature,
  /// An ECDSA error
  Ecdsa(::secp256k1::Error),
  /// An OP_ELSE happened while not in an OP_IF tree
  ElseWithoutIf,
  /// An OP_ENDIF happened while not in an OP_IF tree
  EndifWithoutIf,
  /// An OP_EQUALVERIFY failed (expected, gotten)
  EqualVerifyFailed(String, String),
  /// An OP_IF happened with an empty stack
  IfEmptyStack,
  /// An illegal opcode appeared in the script (does not need to be executed)
  IllegalOpcode,
  /// The interpreter overflowed its stack. This never happens for
  /// script evaluation, only non-consensus analysis passes.
  InterpreterStackOverflow,
  /// Some opcode expected a parameter, but it was missing or truncated
  EarlyEndOfScript,
  /// An OP_RETURN or synonym was executed
  ExecutedReturn,
  /// A multisig tx with negative or too many keys
  MultisigBadKeyCount(isize),
  /// A multisig tx with negative or too many signatures
  MultisigBadSigCount(isize),
  /// Used OP_PICK with a negative index
  NegativePick,
  /// Used OP_ROLL with a negative index
  NegativeRoll,
  /// Tried to execute a signature operation but no transaction context was provided
  NoTransaction,
  /// An OP_NUMEQUALVERIFY failed (expected, gotten)
  NumEqualVerifyFailed(i64, i64),
  /// Tried to read an array off the stack as a number when it was more than 4 bytes
  NumericOverflow,
  /// Some stack operation was done with an empty stack
  PopEmptyStack,
  /// Analysis was unable to determine script input
  Unanalyzable,
  /// Analysis showed script cannot be satisfied
  Unsatisfiable,
  /// An OP_VERIFY happened with an empty stack
  VerifyEmptyStack,
  /// An OP_VERIFY happened with zero on the stack
  VerifyFailed,
}

/// A rule for validating an abstract stack element
pub struct Validator {
  /// List of other elements to pass to both `check` and `update`
  args: Vec<usize>,
  /// Function which confirms that the current value is consistent with
  /// the stack state, returning `false` if not.
  check: fn(&AbstractStackElem, &[usize]) -> bool,
  /// Function which updates the current stack based on the element's
  /// value, if it has a value, otherwise updates the element's value
  /// based on the current stack, if possible. Returns `false` if it
  /// is forced to do something inconsistent.
  update: fn(&mut AbstractStackElem, &[usize]) -> Result<(), Error>
}

impl Clone for Validator {
  fn clone(&self) -> Validator {
    Validator {
      args: self.args.clone(),
      check: self.check,
      update: self.update
    }
  }
}

// Validators
fn check_op_size(elem: &AbstractStackElem, others: &[usize]) -> bool {
  let other = unsafe { elem.lookup(others[0]) };
  elem.num_hi() >= other.len_lo() as i64 &&
  elem.num_lo() <= other.len_hi() as i64
}

fn update_op_size(elem: &mut AbstractStackElem, others: &[usize])
                  -> Result<(), Error> {
  let (lo, hi) = {
    let one = unsafe { elem.lookup(others[0]) };
    (one.len_lo() as i64, one.len_hi() as i64)
  };
  try!(elem.set_numeric());
  try!(elem.set_num_lo(lo));
  elem.set_num_hi(hi)
}

fn check_op_equal(elem: &AbstractStackElem, others: &[usize]) -> bool {
  let one = unsafe { elem.lookup(others[0]) };
  let two = unsafe { elem.lookup(others[1]) };
  match elem.bool_value() {
    None => true,
    Some(false) => {
      (one.num_value().is_none() || two.num_value().is_none() ||
       one.num_value().unwrap() != two.num_value().unwrap()) &&
      (one.bool_value() != Some(false) || two.bool_value() != Some(false)) &&
      (one.raw_value().is_none() || two.raw_value().is_none() ||
       one.raw_value().unwrap() != two.raw_value().unwrap())
    }
    Some(true) => {
      one.len_lo() <= two.len_hi() &&
      one.len_hi() >= two.len_lo() &&
      one.num_lo() <= two.num_hi() &&
      one.num_hi() >= two.num_lo() &&
      (one.bool_value().is_none() || two.bool_value().is_none() ||
       one.bool_value().unwrap() == two.bool_value().unwrap()) &&
      (one.raw_value().is_none() || two.raw_value().is_none() ||
       one.raw_value().unwrap() == two.raw_value().unwrap())
    }
  }
}

fn update_boolean(elem: &mut AbstractStackElem) 
                 -> Result<(), Error> {
  // Test boolean values
  elem.bool_val = Some(true);
  let true_works = elem.validate();
  elem.bool_val = Some(false);
  let false_works = elem.validate();
  elem.bool_val = None;
  // Update according to what worked
  match (true_works, false_works) {
    (true,  true)  => Ok(()),
    (false, false) => Err(Error::AnalyzeNeitherBoolWorks),
    (true,  false) => elem.set_bool_value(true),
    (false, true)  => elem.set_bool_value(false)
  }
}

fn update_op_equal(elem: &mut AbstractStackElem, others: &[usize])
                   -> Result<(), Error> {
  match elem.bool_value() {
    None => update_boolean(elem),
    Some(false) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      let two = unsafe { elem.lookup_mut(others[1]) };
      // Booleans are the only thing we can do something useful with re "not equal"
      match (one.bool_value(), two.bool_value()) {
        (None, None) => Ok(()),
        (None, Some(x)) => one.set_bool_value(!x),
        (Some(x), None) => two.set_bool_value(!x),
        (Some(x), Some(y)) if x == y => Err(Error::Unsatisfiable),
        (Some(_), Some(_)) => Ok(())
      }
    }
    Some(true) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      let two = unsafe { elem.lookup_mut(others[1]) };
      // Equalize numeric bounds
      try!(one.set_num_lo(two.num_lo()));
      try!(one.set_num_hi(two.num_hi()));
      try!(two.set_num_lo(one.num_lo()));
      try!(two.set_num_hi(one.num_hi()));
      // Equalize boolean values
      match (one.bool_value(), two.bool_value()) {
        (None, None) => {},
        (None, Some(x)) => try!(one.set_bool_value(x)),
        (Some(x), None) => try!(two.set_bool_value(x)),
        (Some(x), Some(y)) if x == y => {},
        (Some(_), Some(_)) => { return Err(Error::Unsatisfiable); }
      }
      // Equalize full values
      match (one.raw_value().map(|r| r.to_vec()),
             two.raw_value().map(|r| r.to_vec())) {
        (None, None) => {},
        (None, Some(x)) => try!(one.set_value(&x)),
        (Some(x), None) => try!(two.set_value(&x)),
        (Some(x), Some(y)) => { if x != y { return Err(Error::Unsatisfiable); } }
      }
      Ok(())
    }
  }
}

fn check_op_not(elem: &AbstractStackElem, others: &[usize]) -> bool {
  let one = unsafe { elem.lookup(others[0]) };
  if !one.may_be_numeric() {
    return false;
  }

  match elem.bool_value() {
    None => true,
    Some(false) => one.num_hi() != 0 || one.num_lo() != 0,
    Some(true) => one.num_hi() >= 0 && one.num_lo() <= 0
  }
}

fn update_op_not(elem: &mut AbstractStackElem, others: &[usize])
                 -> Result<(), Error> {
  match elem.bool_value() {
    None => update_boolean(elem),
    Some(false) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      try!(one.set_numeric());
      match one.bool_value() {
        None => one.set_bool_value(true),
        Some(true) => Ok(()),
        Some(false) => Err(Error::Unsatisfiable)
      }
    }
    Some(true) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      try!(one.set_numeric());
      match one.bool_value() {
        None => one.set_num_value(0),
        Some(true) => Err(Error::Unsatisfiable),
        Some(false) => Ok(())
      }
    }
  }
}

fn check_op_0notequal(elem: &AbstractStackElem, others: &[usize]) -> bool {
  let one = unsafe { elem.lookup(others[0]) };
  if !one.may_be_numeric() { return false; }
  match elem.bool_value() {
    None => true,
    Some(false) => one.num_hi() >= 0 && one.num_lo() <= 0,
    Some(true) => one.num_hi() != 0 || one.num_lo() != 0
  }
}

fn update_op_0notequal(elem: &mut AbstractStackElem, others: &[usize])
                       -> Result<(), Error> {
  match elem.bool_value() {
    None => update_boolean(elem),
    Some(false) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      try!(one.set_numeric());
      match one.bool_value() {
        None => one.set_num_value(0),
        Some(true) => Err(Error::Unsatisfiable),
        Some(false) => Ok(())
      }
    }
    Some(true) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      try!(one.set_numeric());
      match one.bool_value() {
        None => one.set_bool_value(true),
        Some(true) => Ok(()),
        Some(false) => Err(Error::Unsatisfiable)
      }
    }
  }
}

fn check_op_numequal(elem: &AbstractStackElem, others: &[usize]) -> bool {
  let one = unsafe { elem.lookup(others[0]) };
  let two = unsafe { elem.lookup(others[1]) };
  if !one.may_be_numeric() { return false; }
  if !two.may_be_numeric() { return false; }
  match elem.bool_value() {
    None => true,
    Some(false) => {
      (one.num_value().is_none() || two.num_value().is_none() ||
       one.num_value().unwrap() != two.num_value().unwrap()) &&
      (one.bool_value().is_none() || two.bool_value().is_none() ||
       one.bool_value().unwrap() != two.bool_value().unwrap())
    }
    Some(true) => {
      one.num_lo() <= two.num_hi() &&
      one.num_hi() >= two.num_lo() &&
      (one.num_value().is_none() || two.num_value().is_none() ||
       one.num_value().unwrap() == two.num_value().unwrap()) &&
      (one.bool_value().is_none() || two.bool_value().is_none() ||
       one.bool_value().unwrap() == two.bool_value().unwrap())
    }
  }
}

fn update_op_numequal(elem: &mut AbstractStackElem, others: &[usize])
                      -> Result<(), Error> {
  match elem.bool_value() {
    None => update_boolean(elem),
    Some(false) => {
      // todo: find a way to force the numbers to be nonequal
      Ok(())
    }
    Some(true) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      let two = unsafe { elem.lookup_mut(others[1]) };
      try!(one.set_numeric());
      try!(two.set_numeric());
      try!(one.set_num_lo(two.num_lo()));
      try!(one.set_num_hi(two.num_hi()));
      try!(two.set_num_lo(one.num_lo()));
      two.set_num_hi(one.num_hi())
    }
  }
}

fn check_op_numnotequal(elem: &AbstractStackElem, others: &[usize]) -> bool {
  let one = unsafe { elem.lookup(others[0]) };
  let two = unsafe { elem.lookup(others[1]) };
  if !one.may_be_numeric() { return false; }
  if !two.may_be_numeric() { return false; }
  match elem.bool_value() {
    None => true,
    Some(false) => one.may_be_lt(two) || one.may_be_gt(two),
    Some(true) => one.may_be_lteq(two) && one.may_be_gteq(two)
  }
}

fn update_op_numnotequal(elem: &mut AbstractStackElem, others: &[usize])
                         -> Result<(), Error> {
  match elem.bool_value() {
    None => update_boolean(elem),
    Some(false) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      let two = unsafe { elem.lookup_mut(others[1]) };
      try!(one.set_numeric());
      try!(two.set_numeric());
      try!(one.set_num_lo(two.num_lo()));
      try!(one.set_num_hi(two.num_hi()));
      try!(two.set_num_lo(one.num_lo()));
      two.set_num_hi(one.num_hi())
    }
    Some(true) => {
      // todo: find a way to force the numbers to be nonequal
      Ok(())
    }
  }
}

fn check_op_numlt(elem: &AbstractStackElem, others: &[usize]) -> bool {
  let one = unsafe { elem.lookup(others[0]) };
  let two = unsafe { elem.lookup(others[1]) };
  if !one.may_be_numeric() { return false; }
  if !two.may_be_numeric() { return false; }
  match elem.bool_value() {
    None => true,
    Some(true) => one.may_be_lt(two),
    Some(false) => one.may_be_gteq(two),
  }
}

fn update_op_numlt(elem: &mut AbstractStackElem, others: &[usize])
                   -> Result<(), Error> {
  match elem.bool_value() {
    None => update_boolean(elem),
    Some(true) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      let two = unsafe { elem.lookup_mut(others[1]) };
      try!(one.set_numeric());
      try!(two.set_numeric());

      try!(one.set_num_hi(two.num_hi() - 1));
      two.set_num_lo(one.num_lo() + 1)
    }
    Some(false) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      let two = unsafe { elem.lookup_mut(others[1]) };
      try!(one.set_numeric());
      try!(two.set_numeric());

      try!(one.set_num_lo(two.num_lo()));
      two.set_num_hi(one.num_hi())
    }
  }
}

fn check_op_numgt(elem: &AbstractStackElem, others: &[usize]) -> bool {
  let one = unsafe { elem.lookup(others[0]) };
  let two = unsafe { elem.lookup(others[1]) };
  if !one.may_be_numeric() { return false; }
  if !two.may_be_numeric() { return false; }
  match elem.bool_value() {
    None => true,
    Some(true) => one.may_be_gt(two),
    Some(false) => one.may_be_lteq(two)
  }
}

fn update_op_numgt(elem: &mut AbstractStackElem, others: &[usize])
                   -> Result<(), Error> {
  match elem.bool_value() {
    None => try!(update_boolean(elem)),
    Some(true) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      let two = unsafe { elem.lookup_mut(others[1]) };
      try!(one.set_numeric());
      try!(two.set_numeric());

      try!(one.set_num_lo(two.num_lo() + 1));
      try!(two.set_num_hi(one.num_hi() - 1));
    }
    Some(false) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      let two = unsafe { elem.lookup_mut(others[1]) };
      try!(one.set_numeric());
      try!(two.set_numeric());

      try!(one.set_num_hi(two.num_hi()));
      try!(two.set_num_lo(one.num_lo()));
    }
  }
  Ok(())
}

fn check_op_numlteq(elem: &AbstractStackElem, others: &[usize]) -> bool {
  let one = unsafe { elem.lookup(others[0]) };
  let two = unsafe { elem.lookup(others[1]) };
  if !one.may_be_numeric() { return false; }
  if !two.may_be_numeric() { return false; }
  match elem.bool_value() {
    None => true,
    Some(false) => one.may_be_gt(two),
    Some(true) => one.may_be_lteq(two)
  }
}

fn update_op_numlteq(elem: &mut AbstractStackElem, others: &[usize])
                   -> Result<(), Error> {
  match elem.bool_value() {
    None => try!(update_boolean(elem)),
    Some(true) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      let two = unsafe { elem.lookup_mut(others[1]) };
      try!(one.set_numeric());
      try!(two.set_numeric());

      try!(one.set_num_hi(two.num_hi()));
      try!(two.set_num_lo(one.num_lo()));
    }
    Some(false) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      let two = unsafe { elem.lookup_mut(others[1]) };
      try!(one.set_numeric());
      try!(two.set_numeric());

      try!(one.set_num_lo(two.num_lo() + 1));
      try!(two.set_num_hi(one.num_hi() - 1));
    }
  }
  Ok(())
}

fn check_op_numgteq(elem: &AbstractStackElem, others: &[usize]) -> bool {
  let one = unsafe { elem.lookup(others[0]) };
  let two = unsafe { elem.lookup(others[1]) };
  if !one.may_be_numeric() { return false; }
  if !two.may_be_numeric() { return false; }
  match elem.bool_value() {
    None => true,
    Some(true) => one.may_be_gteq(two),
    Some(false) => one.may_be_lt(two)
  }
}

fn update_op_numgteq(elem: &mut AbstractStackElem, others: &[usize])
                   -> Result<(), Error> {
  match elem.bool_value() {
    None => try!(update_boolean(elem)),
    Some(true) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      let two = unsafe { elem.lookup_mut(others[1]) };
      try!(one.set_numeric());
      try!(two.set_numeric());

      try!(one.set_num_lo(two.num_lo()));
      try!(two.set_num_hi(one.num_hi()));
    }
    Some(false) => {
      let one = unsafe { elem.lookup_mut(others[0]) };
      let two = unsafe { elem.lookup_mut(others[1]) };
      try!(one.set_numeric());
      try!(two.set_numeric());

      try!(one.set_num_hi(two.num_hi() - 1));
      try!(two.set_num_lo(one.num_lo() + 1));
    }
  }
  Ok(())
}

fn check_op_ripemd160(elem: &AbstractStackElem, _: &[usize]) -> bool {
  elem.may_be_hash160()
}

fn update_op_ripemd160(elem: &mut AbstractStackElem, others: &[usize])
                       -> Result<(), Error> {
  try!(elem.set_len_lo(20));
  try!(elem.set_len_hi(20));

  let hash = match unsafe { elem.lookup(others[0]) }.raw_value() {
    None => None,
    Some(x) => {
      let mut out = [0, ..20];
      let mut engine = Ripemd160::new();
      engine.input(x);
      engine.result(out.as_mut_slice());
      Some(out)
    }
  };

  match hash {
    None => Ok(()),
    Some(x) => elem.set_value(&x)
  }
}

fn check_op_sha1(elem: &AbstractStackElem, _: &[usize]) -> bool {
  elem.may_be_hash160()
}

fn update_op_sha1(elem: &mut AbstractStackElem, others: &[usize])
                  -> Result<(), Error> {
  try!(elem.set_len_lo(20));
  try!(elem.set_len_hi(20));

  let hash = match unsafe { elem.lookup(others[0]) }.raw_value() {
    None => None,
    Some(x) => {
      let mut out = [0, ..20];
      let mut engine = Sha1::new();
      engine.input(x);
      engine.result(out.as_mut_slice());
      Some(out)
    }
  };

  match hash {
    None => Ok(()),
    Some(x) => elem.set_value(&x)
  }
}

fn check_op_hash160(elem: &AbstractStackElem, _: &[usize]) -> bool {
  elem.may_be_hash160()
}

fn update_op_hash160(elem: &mut AbstractStackElem, others: &[usize])
                      -> Result<(), Error> {
  try!(elem.set_len_lo(20));
  try!(elem.set_len_hi(20));

  let hash = match unsafe { elem.lookup(others[0]) }.raw_value() {
    None => None,
    Some(x) => {
      let mut out1 = [0, ..32];
      let mut out2 = [0, ..20];
      let mut engine = Sha256::new();
      engine.input(x);
      engine.result(&mut out1);
      let mut engine = Ripemd160::new();
      engine.input(&out1);
      engine.result(&mut out2);
      Some(out2)
    }
  };

  match hash {
    None => Ok(()),
    Some(x) => elem.set_value(&x)
  }
}

fn check_op_sha256(elem: &AbstractStackElem, _: &[usize]) -> bool {
  elem.may_be_hash256()
}

fn update_op_sha256(elem: &mut AbstractStackElem, others: &[usize])
                    -> Result<(), Error> {
  try!(elem.set_len_lo(32));
  try!(elem.set_len_hi(32));

  let hash = match unsafe { elem.lookup(others[0]) }.raw_value() {
    None => None,
    Some(x) => {
      let mut out = [0, ..32];
      let mut engine = Sha256::new();
      engine.input(x);
      engine.result(out.as_mut_slice());
      Some(out)
    }
  };

  match hash {
    None => Ok(()),
    Some(x) => elem.set_value(&x)
  }
}

fn check_op_hash256(elem: &AbstractStackElem, _: &[usize]) -> bool {
  elem.may_be_hash256()
}

fn update_op_hash256(elem: &mut AbstractStackElem, others: &[usize])
                    -> Result<(), Error> {
  try!(elem.set_len_lo(32));
  try!(elem.set_len_hi(32));

  let hash = match unsafe { elem.lookup(others[0]) }.raw_value() {
    None => None,
    Some(x) => {
      let mut out = [0, ..32];
      let mut engine = Sha256::new();
      engine.input(x);
      engine.result(&mut out);
      let mut engine = Sha256::new();
      engine.input(&out);
      engine.result(&mut out);
      Some(out)
    }
  };

  match hash {
    None => Ok(()),
    Some(x) => elem.set_value(&x)
  }
}

fn check_op_checksig(elem: &AbstractStackElem, others: &[usize]) -> bool {
  let one = unsafe { elem.lookup(others[0]) };
  let two = unsafe { elem.lookup(others[1]) };
  match elem.bool_value() {
    None => true,
    Some(false) => true,
    Some(true) => one.may_be_signature() && two.may_be_pubkey()
  }
}

fn update_op_checksig(elem: &mut AbstractStackElem, others: &[usize])
                      -> Result<(), Error> {
  match elem.bool_value() {
    None => update_boolean(elem),
    Some(false) => Ok(()), // nothing we can do to enforce an invalid sig
    Some(true) => {
      let sig = unsafe { elem.lookup_mut(others[0]) };
      let pk  = unsafe { elem.lookup_mut(others[1]) };

      // todo add DER encoding enforcement
      try!(pk.set_len_lo(33));
      try!(pk.set_len_hi(65));
      try!(sig.set_len_lo(75));
      sig.set_len_hi(80)
    }
  }
}

/// An abstract element on the stack, used to describe a satisfying
/// script input
#[derive(Clone)]
pub struct AbstractStackElem {
  /// The raw data, if known
  raw: Option<Vec<u8>>,
  /// Boolean value, if forced
  bool_val: Option<bool>,
  /// Lower bound when read as number
  num_lo: i64,
  /// Upper bound when read as number
  num_hi: i64,
  /// Length lower bound
  len_lo: usize,
  /// Length upper bound
  len_hi: usize,
  /// Relations this must satisfy
  validators: Vec<Validator>,
  /// Index of the element in its stack allocator
  alloc_index: Option<usize>
}

impl AbstractStackElem {
  /// Create a new exact integer
  pub fn new_num(n: i64) -> AbstractStackElem {
    let raw = build_scriptint(n);
    AbstractStackElem {
      num_lo: n,
      num_hi: n,
      len_lo: raw.len(),
      len_hi: raw.len(),
      raw: Some(raw),
      bool_val: Some(n != 0),
      validators: vec![],
      alloc_index: None
    }
  }

  /// Create a new exact boolean
  pub fn new_bool(b: bool) -> AbstractStackElem {
    AbstractStackElem::new_num(if b { 1 } else { 0 })
  }

  /// Create a new exact data
  pub fn new_raw(data: &[u8]) -> AbstractStackElem {
    let n = read_scriptint(data);
    AbstractStackElem {
      num_lo: match n { Ok(n) => n, Err(_) => -(1 << 31) },
      num_hi: match n { Ok(n) => n, Err(_) => 1 << 31 },
      len_lo: data.len(),
      len_hi: data.len(),
      bool_val: Some(read_scriptbool(data)),
      raw: Some(data.to_vec()),
      validators: vec![],
      alloc_index: None
    }
  }

  /// Create a new unknown element
  pub fn new_unknown() -> AbstractStackElem {
    AbstractStackElem {
      num_lo: -(1 << 31),
      num_hi: 1 << 31,
      len_lo: 0,
      len_hi: 1 << 20,  // blocksize limit
      bool_val: None,
      raw: None,
      validators: vec![],
      alloc_index: None
    }
  }

  /// Looks up another stack item by index
  unsafe fn lookup<'a>(&'a self, idx: usize) -> &'a AbstractStackElem {
    let mypos = self as *const _;
    let myidx = self.alloc_index.unwrap() as isize;
    &*mypos.offset(idx as isize - myidx)
  }

  /// Looks up another stack item by index
  unsafe fn lookup_mut<'a>(&'a self, idx: usize) -> &'a mut AbstractStackElem {
    let mypos = self as *const _ as *mut _;
    let myidx = self.alloc_index.unwrap() as isize;
    &mut *mypos.offset(idx as isize - myidx)
  }

  /// Retrieve the boolean value of the stack element, if it can be determined
  pub fn bool_value(&self) -> Option<bool> {
    self.bool_val
  }

  /// Retrieves the raw value of the stack element, if it can be determined
  pub fn raw_value<'a>(&'a self) -> Option<&'a [u8]> {
    self.raw.as_ref().map(|x| &x[..])
  }

  /// Retrieve the upper bound for this element's numeric value.
  /// This can always be determined since there is a fixed upper
  /// bound for all numbers.
  pub fn num_hi(&self) -> i64 {
    self.num_hi
  }

  /// Retrieve the lower bound for this element's numeric value.
  /// This can always be determined since there is a fixed lower
  /// bound for all numbers.
  pub fn num_lo(&self) -> i64 {
    self.num_lo
  }

  /// Retrieve the upper bound for this element's length. This always
  /// exists as a finite value, though the default upper limit is some
  /// impractically large number
  pub fn len_hi(&self) -> usize {
    self.len_hi
  }

  /// Retrieve the lower bound for this element's length. This always
  /// exists since it is at least zero :)
  pub fn len_lo(&self) -> usize {
    self.len_lo
  }

  /// Retries the element's numeric value, if it can be determined
  pub fn num_value(&self) -> Option<i64> {
    let lo = self.num_lo();
    let hi = self.num_hi();
    if lo == hi { Some(lo) } else { None }
  }

  /// Propagate any changes to all nodes which are referenced
  fn update(&mut self) -> Result<(), Error> {
    // Check that this node is consistent before doing any propagation
    if !self.validate() {
      return Err(Error::AnalyzeValidateFailed);
    }

    let validators = self.validators.clone();
    for v in validators.iter().map(|v| v.clone()) {
      try!((v.update)(self, &v.args));
    }
    Ok(())
  }

  /// Check that all rules are satisfied
  fn validate(&mut self) -> bool {
    if self.num_hi < self.num_lo { return false; }
    if self.len_hi < self.len_lo { return false; }

    self.validators.iter().all(|rule| (rule.check)(self, &rule.args))
  }

  /// Sets the boolean value
  pub fn set_bool_value(&mut self, val: bool)
                    -> Result<(), Error> {
    match self.bool_val {
      Some(x) => {
        if x != val { return Err(Error::AnalyzeSetBoolMismatch(val)); }
      }
      None => {
        self.bool_val = Some(val);
        if !val {
          try!(self.set_num_value(0));
        } else if self.num_lo() == 0 && self.num_hi == 1 {
          // This seems like a special case but actually everything that
          // is `set_boolean` satisfies it
          try!(self.set_num_value(1));
        }
        try!(self.update());
      }
    }
    Ok(())
  }

  /// Sets the numeric value
  pub fn set_num_value(&mut self, val: i64) -> Result<(), Error> {
    try!(self.set_num_lo(val));
    self.set_num_hi(val)
  }

  /// Sets the entire value of the 
  pub fn set_value(&mut self, val: &[u8]) -> Result<(), Error> {
    match self.raw_value().map(|x| x.to_vec()) {
      Some(x) => { if &x[..] == val { Ok(()) } else { Err(Error::Unsatisfiable) } }
      None => {
        try!(self.set_len_lo(val.len()));
        try!(self.set_len_hi(val.len()));
        try!(self.set_bool_value(read_scriptbool(val)));
        match read_scriptint(val) {
          Ok(n) => {
            try!(self.set_num_lo(n));
            try!(self.set_num_hi(n));
          }
          Err(_) => {}
        }
        try!(self.set_bool_value(read_scriptbool(val)));
        self.raw = Some(val.to_vec());
        Ok(())
      }
    }
  }

  /// Sets a number to be numerically parseable
  pub fn set_numeric(&mut self) -> Result<(), Error> {
    self.set_len_hi(4)
  }

  /// Whether an element could possibly be a number
  pub fn may_be_numeric(&self) -> bool {
    self.len_lo() <= 4
  }

  /// Whether an element could possibly be a signature
  pub fn may_be_signature(&self) -> bool {
    self.len_lo() <= 78 && self.len_hi() >= 77
    // todo check DER encoding
  }

  /// Whether an element could possibly be a pubkey
  pub fn may_be_pubkey(&self) -> bool {
    ((self.len_lo() <= 33 && self.len_hi() >= 33) ||
     (self.len_lo() <= 65 && self.len_hi() >= 65)) &&
    (self.raw_value().is_none() || PublicKey::from_slice(self.raw_value().unwrap()).is_ok())
  }

  /// Whether an element could possibly be less than another
  pub fn may_be_lt(&self, other: &AbstractStackElem) -> bool {
    self.num_lo() < other.num_hi() &&
    self.num_value().is_none() || other.num_value().is_none() ||
      self.num_value().unwrap() < other.num_value().unwrap()
  }

  /// Whether an element could possibly be greater than another
  pub fn may_be_gt(&self, other: &AbstractStackElem) -> bool {
    self.num_hi() > other.num_lo() &&
    (self.num_value().is_none() || other.num_value().is_none() ||
     self.num_value().unwrap() > other.num_value().unwrap())
  }

  /// Whether an element could possibly be less than or equal to another
  pub fn may_be_lteq(&self, other: &AbstractStackElem) -> bool {
    self.num_lo() <= other.num_hi() &&
    self.num_value().is_none() || other.num_value().is_none() ||
      self.num_value().unwrap() <= other.num_value().unwrap()
  }

  /// Whether an element could possibly be greater than or equal to another
  pub fn may_be_gteq(&self, other: &AbstractStackElem) -> bool {
    self.num_hi() >= other.num_lo() &&
    (self.num_value().is_none() || other.num_value().is_none() ||
     self.num_value().unwrap() >= other.num_value().unwrap())
  }

  /// Whether an element could possibly be a 20-byte hash
  pub fn may_be_hash160(&self) -> bool {
    self.len_lo() <= 20 && self.len_hi() >= 20
  }

  /// Whether an element could possibly be a 32-byte hash
  pub fn may_be_hash256(&self) -> bool {
    self.len_lo() <= 32 && self.len_hi() >= 32
  }

  /// Sets a number to be an opcode-pushed boolean
  pub fn set_boolean(&mut self) -> Result<(), Error> {
    try!(self.set_len_hi(1));
    try!(self.set_num_lo(0));
    self.set_num_hi(1)
  }

  /// Sets a numeric lower bound on a value
  pub fn set_num_lo(&mut self, value: i64) -> Result<(), Error> {
    if self.num_lo < value {
      self.num_lo = value;
      if value > 0 { try!(self.set_bool_value(true)); }
      if value == 0 && self.num_hi == 0 { try!(self.set_bool_value(false)); }
      try!(self.update());
    }
    Ok(())
  }

  /// Sets a numeric upper bound on a value
  pub fn set_num_hi(&mut self, value: i64) -> Result<(), Error> {
    if self.num_hi > value {
      self.num_hi = value;
      if value < 0 { try!(self.set_bool_value(true)); }
      if value == 0 && self.num_lo == 0 { try!(self.set_bool_value(false)); }
      try!(self.update());
    }
    Ok(())
  }

  /// Sets a lower length bound on a value
  pub fn set_len_lo(&mut self, value: usize) -> Result<(), Error> {
    if self.len_lo < value {
      self.len_lo = value;
      if value > 0 { try!(self.set_bool_value(true)); }
      if value == 0 && self.num_hi == 0 { try!(self.set_bool_value(false)); }
      try!(self.update());
    }
    Ok(())
  }

  /// Sets a upper length bound on a value
  pub fn set_len_hi(&mut self, value: usize) -> Result<(), Error> {
    if self.len_hi > value {
      self.len_hi = value;
      try!(self.update());
    }
    Ok(())
  }

  /// Adds some condition on the element
  pub fn add_validator(&mut self, cond: Validator) -> Result<(), Error> {
    self.validators.push(cond);
    self.update()
  }
}


/// The stack used by the script satisfier
#[derive(Clone)]
pub struct AbstractStack {
  /// Actual elements on the stack
  stack: Vec<usize>,
  /// Actual elements on the altstack
  alt_stack: Vec<usize>,
  /// Stack needed to satisfy the script before execution
  initial_stack: Vec<usize>,
  /// Local allocator to allow cloning; refs are indices into here
  alloc: Vec<AbstractStackElem>
}

impl AbstractStack {
  /// Construct a new empty abstract stack
  pub fn new() -> AbstractStack {
    AbstractStack {
      stack: vec![],
      alt_stack: vec![],
      initial_stack: vec![],
      alloc: vec![]
    }
  }

  fn allocate(&mut self, mut elem: AbstractStackElem) -> usize {
    elem.alloc_index = Some(self.alloc.len());
    self.alloc.push(elem);
    self.alloc.len() - 1
  }

  fn push_initial(&mut self, elem: AbstractStackElem) {
    let idx = self.allocate(elem);
    self.initial_stack.insert(0, idx);
    self.stack.insert(0, idx);
  }

  /// Construct the initial stack in the end
  pub fn build_initial_stack(&self) -> Vec<AbstractStackElem> {
    let res: Vec<AbstractStackElem> =
        self.initial_stack.iter().map(|&i| self.alloc[i].clone()).collect();
    res
  }

  /// Increase the stack size to `n`, adding elements to the initial
  /// stack as necessary
  pub fn require_n_elems(&mut self, n: usize) {
    while self.stack.len() < n {
      self.push_initial(AbstractStackElem::new_unknown());
    }
  }

  /// Lookup an element by index
  pub fn get_elem(&self, alloc_index: usize) -> &AbstractStackElem {
    &self.alloc[alloc_index]
  }

  /// Lookup an element by index
  pub fn get_elem_mut(&mut self, alloc_index: usize) -> &mut AbstractStackElem {
    self.alloc.get_mut(alloc_index)
  }

  /// Push a copy of an existing element by index
  pub fn push(&mut self, elem: usize) {
    self.stack.push(elem);
  }

  /// Push a new element
  pub fn push_alloc<'a>(&'a mut self, elem: AbstractStackElem) -> &'a mut AbstractStackElem {
    let idx = self.allocate(elem);
    self.stack.push(idx);
    self.alloc.get_mut(idx)
  }


  /// Obtain a mutable element to the top stack element
  pub fn peek_mut<'a>(&'a mut self) -> &'a mut AbstractStackElem {
    if self.stack.len() == 0 {
      self.push_initial(AbstractStackElem::new_unknown());
    }

    self.alloc.get_mut(*self.stack.last().unwrap())
  }

  /// Obtain a stackref to the current top element
  pub fn peek_index(&mut self) -> usize {
    if self.stack.len() == 0 {
      self.push_initial(AbstractStackElem::new_unknown());
    }
    *self.stack.last().unwrap()
  }

  /// Drop the top stack item
  fn pop(&mut self) -> usize {
    if self.stack.len() == 0 {
      self.push_initial(AbstractStackElem::new_unknown());
    }
    self.stack.pop().unwrap()
  }

  /// Obtain a mutable reference to the top stack item, but remove it from the stack
  fn pop_mut<'a>(&'a mut self) -> &'a mut AbstractStackElem {
    if self.stack.len() == 0 {
      self.push_initial(AbstractStackElem::new_unknown());
    }

    self.alloc.get_mut(self.stack.pop().unwrap())
  }


  /// Move the top stack item to the altstack
  pub fn to_altstack(&mut self) {
    if self.stack.len() == 0 {
      self.push_initial(AbstractStackElem::new_unknown());
    }

    let pop = self.stack.pop().unwrap();
    self.alt_stack.push(pop);
  }

  /// Move the top altstack item to the stack, failing if the
  /// altstack is empty. (Note that input scripts pass their
  /// stack to the output script but /not/ the altstack, so
  /// there is no input that can make an empty altstack nonempty.)
  pub fn from_altstack(&mut self) -> Result<(), Error> {
    match self.alt_stack.pop() {
      Some(x) => { self.stack.push(x); Ok(()) }
      None => Err(Error::PopEmptyStack)
    }
  }

  /// Immutable view of the current stack as a slice (to be compatible
  /// with the `stack_opcode!` macro
  pub fn as_slice<'a>(&'a self) -> &'a [usize] {
    self.stack.as_slice()
  }

  /// Immutable view of the current stack as a slice of bytes
  pub fn slice_to<'a>(&'a self, n: usize) -> &'a [usize] {
    self.stack.slice_to(n)
  }

  /// Mutable view of the current stack as a slice (to be compatible
  /// with the `stack_opcode!` macro
  fn as_mut_slice<'a>(&'a mut self) -> &'a mut [usize] {
    self.stack.as_mut_slice()
  }

  /// Length of the current stack
  fn len(&self) -> usize {
    self.stack.len()
  }

  /// Delete an element from the middle of the current stack
  fn remove(&mut self, idx: usize) {
    self.stack.remove(idx);
  }
}

impl serde::Serialize for Error {
  fn serialize<S>(&self, serializer: &mut S) -> Result<(), S::Error>
      where S: serde::Serializer,
  {
      serializer.visit_str(&self.to_string())
  }
}

/// A single iteration of a script execution
#[derive(PartialEq, Eq, Debug, Clone)]
pub struct TraceIteration {
  index: usize,
  op_count: usize,
  opcode: opcodes::All,
  executed: bool,
  errored: bool,
  effect: opcodes::Class,
  stack: Vec<String>
}

/// A full trace of a script execution
#[derive(PartialEq, Eq, Debug, Clone)]
pub struct ScriptTrace {
  /// A copy of the script
  pub script: Script,
  /// A copy of the script's initial stack, hex-encoded
  pub initial_stack: Vec<String>,
  /// A list of iterations
  pub iterations: Vec<TraceIteration>,
  /// An error if one was returned, or None
  pub error: Option<Error>
}

/// Hashtype of a transaction, encoded in the last byte of a signature,
/// specifically in the last 5 bits `byte & 31`
#[derive(PartialEq, Eq, Debug, Clone)]
pub enum SigHashType {
  /// 0x1: Sign all outputs
  All,
  /// 0x2: Sign no outputs --- anyone can choose the destination
  None,
  /// 0x3: Sign the output whose index matches this input's index. If none exists,
  /// sign the hash `0000000000000000000000000000000000000000000000000000000000000001`.
  /// (This rule is probably an unintentional C++ism, but it's consensus so we have
  /// to follow it.)
  Single,
  /// ???: Anything else is a non-canonical synonym for SigHashAll, for example
  /// zero appears a few times in the chain
  Unknown
}

impl SigHashType {
   /// Returns a SigHashType along with a boolean indicating whether
   /// the `ANYONECANPAY` flag is set, read from the last byte of a signature.
   fn from_signature(signature: &[u8]) -> (SigHashType, bool) {
     let byte = signature[signature.len() - 1];
     let sighash = match byte & 0x1f {
       1 => SigHashType::All,
       2 => SigHashType::None,
       3 => SigHashType::Single,
       _ => SigHashType::Unknown
     };
     (sighash, (byte & 0x80) != 0)
   }
}

/// A structure that can hold either a slice or vector, as necessary
#[derive(Clone, Debug)]
pub enum MaybeOwned<'a> {
  /// Freshly llocated memory
  Owned(Vec<u8>),
  /// Pointer into the original script
  Borrowed(&'a [u8])
}

impl<'a> PartialEq for MaybeOwned<'a> {
  #[inline]
  fn eq(&self, other: &MaybeOwned) -> bool { &self[..] == &other[..] }
}

impl<'a> Eq for MaybeOwned<'a> {}

impl<'a> ops::Index<usize> for MaybeOwned<'a> {
  type Output = u8;

  #[inline]
  fn index(&self, index: usize) -> &u8 {
    match *self {
      MaybeOwned::Owned(ref v) => &v[index],
      MaybeOwned::Borrowed(ref s) => &s[index]
    }
  }
}

impl<'a> ops::Index<ops::Range<usize>> for MaybeOwned<'a> {
  type Output = [u8];

  #[inline]
  fn index(&self, index: ops::Range<usize>) -> &[u8] {
    match *self {
      MaybeOwned::Owned(ref v) => &v[index],
      MaybeOwned::Borrowed(ref s) => &s[index]
    }
  }
}

impl<'a> ops::Index<ops::RangeTo<usize>> for MaybeOwned<'a> {
  type Output = [u8];

  #[inline]
  fn index(&self, index: ops::RangeTo<usize>) -> &[u8] {
    match *self {
      MaybeOwned::Owned(ref v) => &v[index],
      MaybeOwned::Borrowed(ref s) => &s[index]
    }
  }
}

impl<'a> ops::Index<ops::RangeFrom<usize>> for MaybeOwned<'a> {
  type Output = [u8];

  #[inline]
  fn index(&self, index: ops::RangeFrom<usize>) -> &[u8] {
    match *self {
      MaybeOwned::Owned(ref v) => &v[index],
      MaybeOwned::Borrowed(ref s) => &s[index]
    }
  }
}

impl<'a> ops::Index<ops::RangeFull> for MaybeOwned<'a> {
  type Output = [u8];

  #[inline]
  fn index(&self, _: ops::RangeFull) -> &[u8] {
    match *self {
      MaybeOwned::Owned(ref v) => &v[..],
      MaybeOwned::Borrowed(ref s) => &s[..]
    }
  }
}

impl<'a> MaybeOwned<'a> {
  /// The number of bytes stored in the vector
  #[inline]
  fn len(&self) -> usize {
    match *self {
      MaybeOwned::Owned(ref v) => v.len(),
      MaybeOwned::Borrowed(ref s) => s.len()
    }
  }
}

static SCRIPT_TRUE: &'static [u8] = &[0x01];
static SCRIPT_FALSE: &'static [u8] = &[0x00];

/// Helper to encode an integer in script format
fn build_scriptint(n: i64) -> Vec<u8> {
  if n == 0 { return vec![] }

  let neg = n < 0;

  let mut abs = if neg { -n } else { n } as usize;
  let mut v = vec![];
  while abs > 0xFF {
    v.push((abs & 0xFF) as u8);
    abs >>= 8;
  }
  // If the number's value causes the sign bit to be set, we need an extra
  // byte to get the correct value and correct sign bit
  if abs & 0x80 != 0 {
    v.push(abs as u8);
    v.push(if neg { 0x80u8 } else { 0u8 });
  }
  // Otherwise we just set the sign bit ourselves
  else {
    abs |= if neg { 0x80 } else { 0 };
    v.push(abs as u8);
  }
  v
}

/// Helper to decode an integer in script format
/// Notice that this fails on overflow: the result is the same as in
/// bitcoind, that only 4-byte signed-magnitude values may be read as
/// numbers. They can be added or subtracted (and a long time ago,
/// multiplied and divided), and this may result in numbers which
/// can't be written out in 4 bytes or less. This is ok! The number
/// just can't be read as a number again.
/// This is a bit crazy and subtle, but it makes sense: you can load
/// 32-bit numbers and do anything with them, which back when mult/div
/// was allowed, could result in up to a 64-bit number. We don't want
/// overflow since that's suprising --- and we don't want numbers that
/// don't fit in 64 bits (for efficiency on modern processors) so we
/// simply say, anything in excess of 32 bits is no longer a number.
/// This is basically a ranged type implementation.
pub fn read_scriptint(v: &[u8]) -> Result<i64, Error> {
  let len = v.len();
  if len == 0 { return Ok(0); }
  if len > 4 { return Err(Error::NumericOverflow); }

  let (mut ret, sh) = v.iter()
                       .fold((0, 0), |(acc, sh), n| (acc + ((*n as i64) << sh), sh + 8));
  if v[len - 1] & 0x80 != 0 {
    ret &= (1 << sh - 1) - 1;
    ret = -ret;
  }
  Ok(ret)
}

/// This is like "read_scriptint then map 0 to false and everything
/// else as true", except that the overflow rules don't apply.
#[inline]
pub fn read_scriptbool(v: &[u8]) -> bool {
  !(v.len() == 0 ||
    ((v[v.len() - 1] == 0 || v[v.len() - 1] == 0x80) &&
     v.iter().rev().skip(1).all(|&w| w == 0)))
}

/// Read a script-encoded unsigned integer
pub fn read_uint(data: &[u8], size: usize) -> Result<usize, Error> {
  if data.len() < size {
    Err(Error::EarlyEndOfScript)
  } else {
    let mut ret = 0;
    for i in 0..size {
      ret += (data[i] as usize) << (i * 8);
    }
    Ok(ret)
  }
}

/// Check a signature -- returns an error that is currently just translated
/// into a 0/1 to push onto the script stack
fn check_signature(sig_slice: &[u8], pk_slice: &[u8], script: Vec<u8>,
                   tx: &Transaction, input_index: usize) -> Result<(), Error> {

  // Check public key
  let pubkey = PublicKey::from_slice(pk_slice);
  if pubkey.is_err() {
    return Err(Error::BadPublicKey);
  }
  let pubkey = pubkey.unwrap();

  // Check signature and hashtype
  if sig_slice.len() == 0 {
    return Err(Error::BadSignature);
  }
  let (hashtype, anyone_can_pay) = SigHashType::from_signature(sig_slice);

  // Compute the transaction data to be hashed
  let mut tx_copy = Transaction { version: tx.version, lock_time: tx.lock_time,
                                  input: Vec::with_capacity(tx.input.len()),
                                  output: tx.output.clone() };

  // Put the script into an Option so that we can move it (via take_unwrap())
  // in the following branch/loop without the move-checker complaining about
  // multiple moves.
  let mut script = Some(script);
  if anyone_can_pay {
    // For anyone-can-pay transactions we replace the whole input array
    // with just the current input, to ensure the others have no effect.
    let mut old_input = tx.input[input_index].clone();
    old_input.script_sig = Script(script.take().unwrap().into_boxed_slice());
    tx_copy.input = vec![old_input];
  } else {
    // Otherwise we keep all the inputs, blanking out the others and even
    // resetting their sequence no. if appropriate
    for (n, input) in tx.input.iter().enumerate() {
      // Zero out the scripts of other inputs
      let mut new_input = TxIn { prev_hash: input.prev_hash,
                                 prev_index: input.prev_index,
                                 sequence: input.sequence,
                                 script_sig: Script::new() };
      if n == input_index {
        new_input.script_sig = Script(script.take().unwrap().into_boxed_slice());
      } else {
        new_input.script_sig = Script::new();
        // If we aren't signing them, also zero out the sequence number
        if hashtype == SigHashType::Single || hashtype == SigHashType::None {
          new_input.sequence = 0;
        }
      }
      tx_copy.input.push(new_input);
    }
  }

  // Erase outputs as appropriate
  let mut sighash_single_bug = false;
  match hashtype {
    SigHashType::None => { tx_copy.output = vec![]; }
    SigHashType::Single => {
      if input_index < tx_copy.output.len() {
        let mut new_outs = Vec::with_capacity(input_index + 1);
        for _ in 0..input_index {
          new_outs.push(Default::default())
        }
        new_outs.push(tx_copy.output.swap_remove(input_index).unwrap());
        tx_copy.output = new_outs;
      } else {
        sighash_single_bug = true;
      }
    }
    SigHashType::All | SigHashType::Unknown => {}
  }

  let signature_hash = if sighash_single_bug {
    vec![1, 0, 0, 0, 0, 0, 0, 0,
         0, 0, 0, 0, 0, 0, 0, 0,
         0, 0, 0, 0, 0, 0, 0, 0,
         0, 0, 0, 0, 0, 0, 0, 0]
  } else {
    let mut data_to_sign = serialize(&tx_copy).unwrap();
    data_to_sign.push(*sig_slice.last().unwrap());
    data_to_sign.push(0);
    data_to_sign.push(0);
    data_to_sign.push(0);
    serialize(&Sha256dHash::from_data(&data_to_sign[..])).unwrap()
  };

  Secp256k1::verify_raw(&signature_hash[..], sig_slice, &pubkey).map_err(Error::Ecdsa)
}

// Macro to translate English stack instructions into Rust code.
// All number are references to stack positions: 1 is the top,
// 2 is the second-to-top, etc. The numbers do not change within
// an opcode; to delete the top two items do `drop 1 drop 2`
// rather than `drop 1 drop 1`, which will fail.
// This is useful for only about a dozen opcodes, but those ones
// were really hard to read and verify -- see OP_PICK and OP_ROLL
// for an example of what Rust vector-stack manipulation looks
// like.
macro_rules! stack_opcode {
  ($stack:ident($min:expr):
       $(require $r:expr);*
       $(copy $c:expr);*
       $(swap ($a:expr, $b:expr));*
       $(perm ($first:expr, $($i:expr),*) );*
       $(drop $d:expr);*
  ) => ({
    $( $stack.require_n_elems($r); )*
    // Record top
    let top = $stack.len();
    // Check stack size
    if top < $min { return Err(Error::PopEmptyStack); }
    // Do copies
    $( let elem = $stack[top - $c].clone();
       $stack.push(elem); )*
    // Do swaps
    $( $stack.as_mut_slice().swap(top - $a, top - $b); )*
    // Do permutations
    $( let first = $first;
       $( $stack.as_mut_slice().swap(top - first, top - $i); )* )*
    // Do drops last so that dropped values will be available above
    $( $stack.remove(top - $d); )*
  });
}

/// Macro to translate numerical operations into stack ones
macro_rules! num_opcode {
  ($stack:ident($($var:ident),*): $op:expr) => ({
    $(
      let $var = &try!(read_scriptint(match $stack.pop() {
        Some(elem) => elem,
        None => { return Err(Error::PopEmptyStack); }
      })[..]);
    )*
    $stack.push(MaybeOwned::Owned(build_scriptint($op)));
    // Return a tuple of all the variables
    ($( $var ),*)
  });
}

macro_rules! unary_opcode_satisfy {
  ($stack:ident, $op:ident) => ({
    let one = $stack.pop();
    let cond = $stack.push_alloc(AbstractStackElem::new_unknown());
    try!(cond.add_validator(Validator { args: vec![one],
                                        check: concat_idents!(check_, $op),
                                        update: concat_idents!(update_, $op) }));
  })
}

macro_rules! boolean_opcode_satisfy {
  ($stack:ident, unary $op:ident) => ({
    let one = $stack.pop();
    let cond = $stack.push_alloc(AbstractStackElem::new_unknown());
    try!(cond.set_boolean());
    try!(cond.add_validator(Validator { args: vec![one],
                                        check: concat_idents!(check_, $op),
                                        update: concat_idents!(update_, $op) }));
  });
  ($stack:ident, binary $op:ident) => ({
    let one = $stack.pop();
    let two = $stack.pop();
    let cond = $stack.push_alloc(AbstractStackElem::new_unknown());
    try!(cond.set_boolean());
    try!(cond.add_validator(Validator { args: vec![two, one],
                                        check: concat_idents!(check_, $op),
                                        update: concat_idents!(update_, $op) }));
  });
  ($stack:ident, ternary $op:ident) => ({
    let one = $stack.pop();
    let two = $stack.pop();
    let three = $stack.pop();
    let mut cond = $stack.push_alloc(AbstractStackElem::new_unknown());
    try!(cond.set_boolean());
    try!(cond.add_validator(Validator { args: vec![three, two, one],
                                        check: concat_idents!(check_, $op),
                                        update: concat_idents!(update_, $op) }));
  });
}

/// Macro to translate hashing operations into stack ones
macro_rules! hash_opcode {
  ($stack:ident, $hash:ident) => ({
    match $stack.pop() {
      None => { return Err(Error::PopEmptyStack); }
      Some(v) => {
        let mut engine = $hash::new();
        engine.input(&v);
        let mut ret = Vec::with_capacity(engine.output_bits() / 8);
        // Force-set the length even though the vector is uninitialized
        // This is OK only because u8 has no destructor
        unsafe { ret.set_len(engine.output_bits() / 8); }
        engine.result(ret.as_mut_slice());
        $stack.push(MaybeOwned::Owned(ret));
      }
    }
  });
}

// OP_VERIFY macro
macro_rules! op_verify {
  ($stack:expr, $err:expr) => (
    match $stack.last().map(|v| read_scriptbool(&v)) {
      None => { return Err(Error::VerifyEmptyStack); }
      Some(false) => { return Err($err); }
      Some(true) => { $stack.pop(); }
    }
  )
}

macro_rules! op_verify_satisfy {
  ($stack:expr) => ({
    try!($stack.peek_mut().set_bool_value(true));
    $stack.pop();
  })
}

impl Script {
  /// Creates a new empty script
  pub fn new() -> Script { Script(vec![].into_boxed_slice()) }

  /// Creates a new script from an existing vector
  pub fn from_vec(v: Vec<u8>) -> Script { Script(v.into_boxed_slice()) }

  /// The length in bytes of the script
  pub fn len(&self) -> usize {
    let &Script(ref raw) = self;
    raw.len()
  }

  /// Adds instructions to push an integer onto the stack. Integers are
  /// encoded as little-endian signed-magnitude numbers, but there are
  /// dedicated opcodes to push some small integers.
  pub fn push_int(&mut self, data: i64) {
    // We can special-case -1, 1-16
    if data == -1 || (data >= 1 && data <=16) {
      let &Script(ref mut raw) = self;
      raw.push(data as u8 + opcodes::All::OP_TRUE as u8);
      return;
    }
    // We can also special-case zero
    if data == 0 {
      let &Script(ref mut raw) = self;
      raw.push(opcodes::All::OP_FALSE as u8);
      return;
    }
    // Otherwise encode it as data
    self.push_scriptint(data);
  }

  /// Adds instructions to push an integer onto the stack, using the explicit
  /// encoding regardless of the availability of dedicated opcodes.
  pub fn push_scriptint(&mut self, data: i64) {
    self.push_slice(&build_scriptint(data));
  }

  /// Adds instructions to push some arbitrary data onto the stack
  pub fn push_slice(&mut self, data: &[u8]) {
    let &Script(ref mut raw) = self;
    // Start with a PUSH opcode
    match data.len() {
      n if n < opcodes::Ordinary::OP_PUSHDATA1 as usize => { raw.push(n as u8); },
      n if n < 0x100 => {
        raw.push(opcodes::Ordinary::OP_PUSHDATA1 as u8);
        raw.push(n as u8);
      },
      n if n < 0x10000 => {
        raw.push(opcodes::Ordinary::OP_PUSHDATA2 as u8);
        raw.push((n % 0x100) as u8);
        raw.push((n / 0x100) as u8);
      },
      n if n < 0x100000000 => {
        raw.push(opcodes::Ordinary::OP_PUSHDATA4 as u8);
        raw.push((n % 0x100) as u8);
        raw.push(((n / 0x100) % 0x100) as u8);
        raw.push(((n / 0x10000) % 0x100) as u8);
        raw.push((n / 0x1000000) as u8);
      }
      _ => panic!("tried to put a 4bn+ sized object into a script!")
    }
    // Then push the acraw
    raw.extend(data.iter().map(|n| *n));
  }

  /// Adds an individual opcode to the script
  pub fn push_opcode(&mut self, data: opcodes::All) {
    let &Script(ref mut raw) = self;
    raw.push(data as u8);
  }

  /// Returns a view into the script as a slice
  pub fn as_slice(&self) -> &[u8] {
    let &Script(ref raw) = self;
    raw.as_slice()
  }

  /// Returns a view into the script as a slice
  pub fn slice_to(&self, n: usize) -> &[u8] {
    let &Script(ref raw) = self;
    raw.slice_to(n)
  }

  /// Returns a view into the script as a slice
  pub fn slice_from(&self, n: usize) -> &[u8] {
    let &Script(ref raw) = self;
    raw.slice_from(n)
  }

  /// Returns a view into the script as a slice
  pub fn slice(&self, s: usize, e: usize) -> &[u8] {
    let &Script(ref raw) = self;
    raw.slice(s, e)
  }

  /// Trace a script
  pub fn trace<'a>(&'a self, stack: &mut Vec<MaybeOwned<'a>>,
                   input_context: Option<(&Transaction, usize)>)
                   -> ScriptTrace {
    let mut trace = ScriptTrace {
        script: self.clone(),
        initial_stack: stack.iter().map(|elem| (&elem[..]).to_hex()).collect(),
        iterations: vec![],
        error: None
    };

    match self.evaluate(stack, input_context, Some(&mut trace.iterations)) {
        Ok(_) => {},
        Err(e) => { trace.error = Some(e.clone()); }
    }
    trace
  }

  /// Evaluate the script, modifying the stack in place
  pub fn evaluate<'a>(&'a self, stack: &mut Vec<MaybeOwned<'a>>,
                      input_context: Option<(&Transaction, usize)>,
                      mut trace: Option<&mut Vec<TraceIteration>>)
                      -> Result<(), Error> {
    let &Script(ref raw) = self;

    let mut codeseparator_index = 0;
    let mut exec_stack = vec![];
    let mut alt_stack = vec![];

    let mut index = 0;
    let mut op_count = 0;
    while index < raw.len() {
      let executing = exec_stack.iter().all(|e| *e);
      let byte = unsafe { *raw.get(index) };
      // Write out the trace, except the stack which we don't know yet
      match trace {
        Some(ref mut t) => {
          let opcode = opcodes::All::Opcode::from_u8(byte);
          t.push(TraceIteration {
            index: index,
            opcode: opcode,
            executed: executing,
            errored: true,
            op_count: op_count,
            effect: opcode.classify(),
            stack: vec!["<failed to execute opcode>".to_string()]
          });
        }
        None => {}
      }
      op_count += 1;
      index += 1;
      // The definitions of all these categories are in opcodes.rs
//println!("read {} as {} as {}  ...  stack before op is {}", byte, opcodes::All::Opcode::from_u8(byte), opcodes::All::Opcode::from_u8(byte).classify(), stack);
      match (executing, opcodes::All::Opcode::from_u8(byte).classify()) {
        // Illegal operations mean failure regardless of execution state
        (_, opcodes::Class::IllegalOp)       => return Err(Error::IllegalOpcode),
        // Push number
        (true, opcodes::Class::PushNum(n))   => stack.push(MaybeOwned::Owned(build_scriptint(n as i64))),
        // Return operations mean failure, but only if executed
        (true, opcodes::Class::ReturnOp)     => return Err(Error::ExecutedReturn),
        // Data-reading statements still need to read, even when not executing
        (_, opcodes::Class::PushBytes(n)) => {
          if raw.len() < index + n { return Err(Error::EarlyEndOfScript); }
          if executing { stack.push(MaybeOwned::Borrowed(raw.slice(index, index + n))); }
          index += n;
        }
        (_, opcodes::Class::Ordinary(opcodes::Ordinary::OP_PUSHDATA1)) => {
          if raw.len() < index + 1 { return Err(Error::EarlyEndOfScript); }
          let n = try!(read_uint(raw.slice_from(index).iter(), 1));
          if raw.len() < index + 1 + n { return Err(Error::EarlyEndOfScript); }
          if executing { stack.push(MaybeOwned::Borrowed(raw.slice(index + 1, index + n + 1))); }
          index += 1 + n;
        }
        (_, opcodes::Class::Ordinary(opcodes::Ordinary::OP_PUSHDATA2)) => {
          if raw.len() < index + 2 { return Err(Error::EarlyEndOfScript); }
          let n = try!(read_uint(raw.slice_from(index).iter(), 2));
          if raw.len() < index + 2 + n { return Err(Error::EarlyEndOfScript); }
          if executing { stack.push(MaybeOwned::Borrowed(raw.slice(index + 2, index + n + 2))); }
          index += 2 + n;
        }
        (_, opcodes::Class::Ordinary(opcodes::Ordinary::OP_PUSHDATA4)) => {
          if raw.len() < index + 4 { return Err(Error::EarlyEndOfScript); }
          let n = try!(read_uint(raw.slice_from(index).iter(), 4));
          if raw.len() < index + 4 + n { return Err(Error::EarlyEndOfScript); }
          if executing { stack.push(MaybeOwned::Borrowed(raw.slice(index + 4, index + n + 4))); }
          index += 4 + n;
        }
        // If-statements take effect when not executing
        (false, opcodes::Class::Ordinary(opcodes::Ordinary::OP_IF)) => exec_stack.push(false),
        (false, opcodes::Class::Ordinary(opcodes::Ordinary::OP_NOTIF)) => exec_stack.push(false),
        (false, opcodes::Class::Ordinary(opcodes::Ordinary::OP_ELSE)) => {
          match exec_stack.last_mut() {
            Some(ref_e) => { *ref_e = !*ref_e }
            None => { return Err(Error::ElseWithoutIf); }
          }
        }
        (false, opcodes::Class::Ordinary(opcodes::Ordinary::OP_ENDIF)) => {
          if exec_stack.pop().is_none() {
            return Err(Error::EndifWithoutIf);
          }
        }
        // No-ops and non-executed operations do nothing
        (true, opcodes::Class::NoOp) | (false, _) => {}
        // Actual opcodes
        (true, opcodes::Class::Ordinary(op)) => {
          match op {
            opcodes::Ordinary::OP_PUSHDATA1 | opcodes::Ordinary::OP_PUSHDATA2 | opcodes::Ordinary::OP_PUSHDATA4 => {
              // handled above
            }
            opcodes::Ordinary::OP_IF => {
              match stack.pop().map(|v| read_scriptbool(&v)) {
                None => { return Err(Error::IfEmptyStack); }
                Some(b) => exec_stack.push(b)
              }
            }
            opcodes::Ordinary::OP_NOTIF => {
              match stack.pop().map(|v| read_scriptbool(&v)) {
                None => { return Err(Error::IfEmptyStack); }
                Some(b) => exec_stack.push(!b),
              }
            }
            opcodes::Ordinary::OP_ELSE => {
              match exec_stack.last_mut() {
                Some(ref_e) => { *ref_e = !*ref_e }
                None => { return Err(Error::ElseWithoutIf); }
              }
            }
            opcodes::Ordinary::OP_ENDIF => {
              if exec_stack.pop().is_none() {
                return Err(Error::EndifWithoutIf);
              }
            }
            opcodes::Ordinary::OP_VERIFY => op_verify!(stack, Error::VerifyFailed),
            opcodes::Ordinary::OP_TOALTSTACK => {
              match stack.pop() {
                None => { return Err(Error::PopEmptyStack); }
                Some(elem) => { alt_stack.push(elem); }
              }
            }
            opcodes::Ordinary::OP_FROMALTSTACK => {
              match alt_stack.pop() {
                None => { return Err(Error::PopEmptyStack); }
                Some(elem) => { stack.push(elem); }
              }
            }
            opcodes::Ordinary::OP_2DROP => stack_opcode!(stack(2): drop 1; drop 2),
            opcodes::Ordinary::OP_2DUP  => stack_opcode!(stack(2): copy 2; copy 1),
            opcodes::Ordinary::OP_3DUP  => stack_opcode!(stack(3): copy 3; copy 2; copy 1),
            opcodes::Ordinary::OP_2OVER => stack_opcode!(stack(4): copy 4; copy 3),
            opcodes::Ordinary::OP_2ROT  => stack_opcode!(stack(6): perm (1, 3, 5);
                                                         perm (2, 4, 6)),
            opcodes::Ordinary::OP_2SWAP => stack_opcode!(stack(4): swap (2, 4); swap (1, 3)),
            opcodes::Ordinary::OP_DROP  => stack_opcode!(stack(1): drop 1),
            opcodes::Ordinary::OP_DUP   => stack_opcode!(stack(1): copy 1),
            opcodes::Ordinary::OP_NIP   => stack_opcode!(stack(2): drop 2),
            opcodes::Ordinary::OP_OVER  => stack_opcode!(stack(2): copy 2),
            opcodes::Ordinary::OP_PICK => {
              let n = match stack.pop() {
                Some(data) => try!(read_scriptint(&data)),
                None => { return Err(Error::PopEmptyStack); }
              };
              if n < 0 { return Err(Error::NegativePick); }
              let n = n as usize;
              stack_opcode!(stack(n + 1): copy n + 1)
            }
            opcodes::Ordinary::OP_ROLL => {
              let n = match stack.pop() {
                Some(data) => try!(read_scriptint(&data)),
                None => { return Err(Error::PopEmptyStack); }
              };
              if n < 0 { return Err(Error::NegativeRoll); }
              let n = n as usize;
              stack_opcode!(stack(n + 1): copy n + 1 drop n + 1)
            }
            opcodes::Ordinary::OP_ROT  => stack_opcode!(stack(3): perm (1, 2, 3)),
            opcodes::Ordinary::OP_SWAP => stack_opcode!(stack(2): swap (1, 2)),
            opcodes::Ordinary::OP_TUCK => stack_opcode!(stack(2): copy 2; copy 1 drop 2),
            opcodes::Ordinary::OP_IFDUP => {
              match stack.last().map(|v| read_scriptbool(&v)) {
                None => { return Err(Error::IfEmptyStack); }
                Some(false) => {}
                Some(true) => { stack_opcode!(stack(1): copy 1); }
              }
            }
            opcodes::Ordinary::OP_DEPTH => {
              let len = stack.len() as i64;
              stack.push(MaybeOwned::Owned(build_scriptint(len)));
            }
            opcodes::Ordinary::OP_SIZE => {
              match stack.last().map(|v| v.len() as i64) {
                None => { return Err(Error::IfEmptyStack); }
                Some(n) => { stack.push(MaybeOwned::Owned(build_scriptint(n))); }
              }
            }
            opcodes::Ordinary::OP_EQUAL | opcodes::Ordinary::OP_EQUALVERIFY => {
              if stack.len() < 2 { return Err(Error::PopEmptyStack); }
              let a = stack.pop().unwrap();
              let b = stack.pop().unwrap();
              stack.push(MaybeOwned::Borrowed(if a == b { SCRIPT_TRUE } else { SCRIPT_FALSE }));
              if op == opcodes::Ordinary::OP_EQUALVERIFY {
                op_verify!(stack, Error::EqualVerifyFailed((&a[..]).to_hex(),
                                                           (&b[..]).to_hex()));
              }
            }
            opcodes::Ordinary::OP_1ADD => { num_opcode!(stack(a): a + 1); }
            opcodes::Ordinary::OP_1SUB => { num_opcode!(stack(a): a - 1); }
            opcodes::Ordinary::OP_NEGATE => { num_opcode!(stack(a): -a); }
            opcodes::Ordinary::OP_ABS => { num_opcode!(stack(a): a.abs()); }
            opcodes::Ordinary::OP_NOT => { num_opcode!(stack(a): if a == 0 {1} else {0}); }
            opcodes::Ordinary::OP_0NOTEQUAL => { num_opcode!(stack(a): if a != 0 {1} else {0}); }
            opcodes::Ordinary::OP_ADD => { num_opcode!(stack(b, a): a + b); }
            opcodes::Ordinary::OP_SUB => { num_opcode!(stack(b, a): a - b); }
            opcodes::Ordinary::OP_BOOLAND => { num_opcode!(stack(b, a): if a != 0 && b != 0 {1} else {0}); }
            opcodes::Ordinary::OP_BOOLOR => { num_opcode!(stack(b, a): if a != 0 || b != 0 {1} else {0}); }
            opcodes::Ordinary::OP_NUMEQUAL => { num_opcode!(stack(b, a): if a == b {1} else {0}); }
            opcodes::Ordinary::OP_NUMNOTEQUAL => { num_opcode!(stack(b, a): if a != b {1} else {0}); }
            opcodes::Ordinary::OP_NUMEQUALVERIFY => {
              let (b, a) = num_opcode!(stack(b, a): if a == b {1} else {0});
              op_verify!(stack, Error::NumEqualVerifyFailed(a, b));
            }
            opcodes::Ordinary::OP_LESSTHAN => { num_opcode!(stack(b, a): if a < b {1} else {0}); }
            opcodes::Ordinary::OP_GREATERTHAN => { num_opcode!(stack(b, a): if a > b {1} else {0}); }
            opcodes::Ordinary::OP_LESSTHANOREQUAL => { num_opcode!(stack(b, a): if a <= b {1} else {0}); }
            opcodes::Ordinary::OP_GREATERTHANOREQUAL => { num_opcode!(stack(b, a): if a >= b {1} else {0}); }
            opcodes::Ordinary::OP_MIN => { num_opcode!(stack(b, a): if a < b {a} else {b}); }
            opcodes::Ordinary::OP_MAX => { num_opcode!(stack(b, a): if a > b {a} else {b}); }
            opcodes::Ordinary::OP_WITHIN => { num_opcode!(stack(c, b, a): if b <= a && a < c {1} else {0}); }
            opcodes::Ordinary::OP_RIPEMD160 => hash_opcode!(stack, Ripemd160),
            opcodes::Ordinary::OP_SHA1 => hash_opcode!(stack, Sha1),
            opcodes::Ordinary::OP_SHA256 => hash_opcode!(stack, Sha256),
            opcodes::Ordinary::OP_HASH160 => {
              hash_opcode!(stack, Sha256);
              hash_opcode!(stack, Ripemd160);
            }
            opcodes::Ordinary::OP_HASH256 => {
              hash_opcode!(stack, Sha256);
              hash_opcode!(stack, Sha256);
            }
            opcodes::Ordinary::OP_CODESEPARATOR => { codeseparator_index = index; }
            opcodes::Ordinary::OP_CHECKSIG | opcodes::Ordinary::OP_CHECKSIGVERIFY => {
              if stack.len() < 2 { return Err(Error::PopEmptyStack); }

              let pk = stack.pop().unwrap();
              let pk_slice = &pk[..];
              let sig = stack.pop().unwrap();
              let sig_slice = &sig[..];

              // Compute the section of script that needs to be hashed: everything
              // from the last CODESEPARATOR, except the signature itself.
              let mut script = raw.slice_from(codeseparator_index).to_vec();
              let mut remove = Script::new();
              remove.push_slice(sig_slice);
              script_find_and_remove(&mut script, &remove);
              script_find_and_remove(&mut script, [opcodes::Ordinary::OP_CODESEPARATOR as u8]);

              // This is as far as we can go without a transaction, so fail here
              if input_context.is_none() { return Err(Error::NoTransaction); }
              // Otherwise unwrap it
              let (tx, input_index) = input_context.unwrap();

              match check_signature( sig_slice, pk_slice, script, tx, input_index) {
                Ok(()) => stack.push(MaybeOwned::Borrowed(SCRIPT_TRUE)),
                _ => stack.push(MaybeOwned::Borrowed(SCRIPT_FALSE)),
              }
              if op == opcodes::Ordinary::OP_CHECKSIGVERIFY { op_verify!(stack, Error::VerifyFailed); }
            }
            opcodes::Ordinary::OP_CHECKMULTISIG | opcodes::Ordinary::OP_CHECKMULTISIGVERIFY => {
              // Read all the keys
              if stack.len() < 1 { return Err(Error::PopEmptyStack); }
              let n_keys = try!(read_scriptint(&stack.pop().unwrap()));
              if n_keys < 0 || n_keys > 20 {
                return Err(Error::MultisigBadKeyCount(n_keys as isize));
              }

              if (stack.len() as i64) < n_keys { return Err(Error::PopEmptyStack); }
              let mut keys = Vec::with_capacity(n_keys as usize);
              for _ in 0..n_keys {
                keys.push(stack.pop().unwrap());
              }

              // Read all the signatures
              if stack.len() < 1 { return Err(Error::PopEmptyStack); }
              let n_sigs = try!(read_scriptint(&stack.pop().unwrap()));
              if n_sigs < 0 || n_sigs > n_keys {
                return Err(Error::MultisigBadSigCount(n_sigs as isize));
              }

              if (stack.len() as i64) < n_sigs { return Err(Error::PopEmptyStack); }
              let mut sigs = Vec::with_capacity(n_sigs as usize);
              for _ in 0..n_sigs {
                sigs.push(stack.pop().unwrap());
              }

              // Pop one more element off the stack to be replicate a consensus bug
              if stack.pop().is_none() { return Err(Error::PopEmptyStack); }

              // Compute the section of script that needs to be hashed: everything
              // from the last CODESEPARATOR, except the signatures themselves.
              let mut script = raw.slice_from(codeseparator_index).to_vec();
              for sig in sigs.iter() {
                let mut remove = Script::new();
                remove.push_slice(&sig);
                script_find_and_remove(&mut script, &remove);
                script_find_and_remove(&mut script, [opcodes::Ordinary::OP_CODESEPARATOR as u8]);
              }

              // This is as far as we can go without a transaction, so fail here
              if input_context.is_none() { return Err(Error::NoTransaction); }
              // Otherwise unwrap it
              let (tx, input_index) = input_context.unwrap();

              // Check signatures
              let mut key_iter = keys.iter();
              let mut sig_iter = sigs.iter();
              let mut key = key_iter.next();
              let mut sig = sig_iter.next();
              loop {
                match (key, sig) {
                  // Try to validate the signature with the given key
                  (Some(k), Some(s)) => {
                    // Move to the next signature if it is valid for the current key
                    if check_signature(&s, &k, script.clone(), tx, input_index).is_ok() {
                      sig = sig_iter.next();
                    }
                    // Move to the next key in any case
                    key = key_iter.next();
                  }
                  // Run out of signatures, success
                  (_, None) => {
                    stack.push(MaybeOwned::Borrowed(SCRIPT_TRUE));
                    break;
                  }
                  // Run out of keys to match to signatures, fail
                  (None, Some(_)) => {
                    stack.push(MaybeOwned::Borrowed(SCRIPT_FALSE));
                    break;
                  }
                }
              }
              if op == opcodes::Ordinary::OP_CHECKMULTISIGVERIFY { op_verify!(stack, Error::VerifyFailed); }
            }
          } // end opcode match
        } // end classification match
      } // end loop
      // Store the stack in the trace
      trace.as_mut().map(|t|
        t.last_mut().map(|t| {
          t.errored = false;
          t.stack = stack.iter().map(|elem| (&elem[..]).to_hex()).collect();
        })
      );
    }
    Ok(())
  }

  /// Checks whether a script pubkey is a p2sh output
  #[inline]
  pub fn is_p2sh(&self) -> bool {
    let &Script(ref raw) = self;
    unsafe {
      raw.len() == 23 &&
      *raw.get(0) == opcodes::All::OP_HASH160 as u8 &&
      *raw.get(1) == opcodes::All::OP_PUSHBYTES_20 as u8 &&
      *raw.get(22) == opcodes::All::OP_EQUAL as u8
    }
  }

  /// Whether a script can be proven to have no satisfying input
  pub fn is_provably_unspendable(&self) -> bool {
    match self.satisfy() {
      Ok(_) => false,
      Err(Error::Unanalyzable) => false,
      Err(_) => true
    }
  }

  /// Evaluate the script to determine whether any possible input will cause it
  /// to accept. Returns true if it is guaranteed to fail; false otherwise.
  pub fn satisfy(&self) -> Result<Vec<AbstractStackElem>, Error> {
    fn recurse<'a>(script: &'a [u8],
                   mut stack: AbstractStack,
                   mut exec_stack: Vec<bool>,
                   depth: usize) -> Result<Vec<AbstractStackElem>, Error> {

      // Avoid doing more than 64k forks
      if depth > 16 { return Err(Error::InterpreterStackOverflow); }

      let mut index = 0;
      while index < script.len() {
        let executing = exec_stack.iter().all(|e| *e);
        let byte = script[index];
        index += 1;
        // The definitions of all these categories are in opcodes.rs
//println!("read {} as {} as {}", byte, opcodes::All::Opcode::from_u8(byte), opcodes::All::Opcode::from_u8(byte).classify());
        match (executing, opcodes::All::from_u8(byte).classify()) {
          // Illegal operations mean failure regardless of execution state
          (_, opcodes::Class::IllegalOp)     => return Err(Error::IllegalOpcode),
          // Push number
          (true, opcodes::Class::PushNum(n)) => { stack.push_alloc(AbstractStackElem::new_num(n as i64)); },
          // Return operations mean failure, but only if executed
          (true, opcodes::Class::ReturnOp)   => return Err(Error::ExecutedReturn),
          // Data-reading statements still need to read, even when not executing
          (_, opcodes::Class::PushBytes(n)) => {
            if script.len() < index + n { return Err(Error::EarlyEndOfScript); }
            if executing {
              stack.push_alloc(AbstractStackElem::new_raw(script.slice(index, index + n)));
            }
            index += n;
          }
          (_, opcodes::Class::Ordinary(opcodes::Ordinary::OP_PUSHDATA1)) => {
            if script.len() < index + 1 { return Err(Error::EarlyEndOfScript); }
            let n = match read_uint(script.slice_from(index).iter(), 1) {
              Ok(n) => n,
              Err(_) => { return Err(Error::EarlyEndOfScript); }
            };
            if script.len() < index + 1 + n { return Err(Error::EarlyEndOfScript); }
            if executing {
              stack.push_alloc(AbstractStackElem::new_raw(script.slice(index + 1, index + n + 1)));
            }
            index += 1 + n;
          }
          (_, opcodes::Class::Ordinary(opcodes::Ordinary::OP_PUSHDATA2)) => {
            if script.len() < index + 2 { return Err(Error::EarlyEndOfScript); }
            let n = match read_uint(script.slice_from(index).iter(), 2) {
              Ok(n) => n,
              Err(_) => { return Err(Error::EarlyEndOfScript); }
            };
            if script.len() < index + 2 + n { return Err(Error::EarlyEndOfScript); }
            if executing {
              stack.push_alloc(AbstractStackElem::new_raw(script.slice(index + 2, index + n + 2)));
            }
            index += 2 + n;
          }
          (_, opcodes::Class::Ordinary(opcodes::Ordinary::OP_PUSHDATA4)) => {
            let n = match read_uint(script.slice_from(index).iter(), 4) {
              Ok(n) => n,
              Err(_) => { return Err(Error::EarlyEndOfScript); }
            };
            if script.len() < index + 4 + n { return Err(Error::EarlyEndOfScript); }
            if executing {
              stack.push_alloc(AbstractStackElem::new_raw(script.slice(index + 4, index + n + 4)));
            }
            index += 4 + n;
          }
          // If-statements take effect when not executing
          (false, opcodes::Class::Ordinary(opcodes::Ordinary::OP_IF)) => exec_stack.push(false),
          (false, opcodes::Class::Ordinary(opcodes::Ordinary::OP_NOTIF)) => exec_stack.push(false),
          (false, opcodes::Class::Ordinary(opcodes::Ordinary::OP_ELSE)) => {
            match exec_stack.last_mut() {
              Some(ref_e) => { *ref_e = !*ref_e }
              None => { return Err(Error::ElseWithoutIf); }
            }
          }
          (false, opcodes::Class::Ordinary(opcodes::Ordinary::OP_ENDIF)) => {
            if exec_stack.pop().is_none() {
              return Err(Error::EndifWithoutIf);
            }
          }
          // No-ops and non-executed operations do nothing
          (true, opcodes::Class::NoOp) | (false, _) => {}
          // Actual opcodes
          (true, opcodes::Class::Ordinary(op)) => {
            match op {
              opcodes::Ordinary::OP_PUSHDATA1 | opcodes::Ordinary::OP_PUSHDATA2 | opcodes::Ordinary::OP_PUSHDATA4 => {
                // handled above
              }
              opcodes::Ordinary::OP_IF => {
                let top_bool = {
                  let top = stack.peek_mut();
                  top.bool_value()
                };
                match top_bool {
                  None => {
                    let mut stack_true = stack.clone();
                    // Try pushing false and see what happens
                    if stack.peek_mut().set_bool_value(false).is_ok() {
                      match recurse(script.slice_from(index - 1), stack, exec_stack.clone(), depth + 1) {
                        Ok(res) => { return Ok(res); }
                        Err(_) => {}
                      }
                    }
                    // Failing that, push true
                    try!(stack_true.peek_mut().set_bool_value(true));
                    return recurse(script.slice_from(index - 1), stack_true, exec_stack, depth + 1);
                  }
                  Some(val) => {
                    stack.pop();
                    exec_stack.push(val)
                  }
                }
              }
              opcodes::Ordinary::OP_NOTIF => {
                let top_bool = {
                  let top = stack.peek_mut();
                  top.bool_value()
                };
                match top_bool {
                  None => {
                    let mut stack_true = stack.clone();
                    // Try pushing false and see what happens
                    if stack.peek_mut().set_bool_value(false).is_ok() {
                      match recurse(script.slice_from(index - 1), stack, exec_stack.clone(), depth + 1) {
                        Ok(res) => { return Ok(res); }
                        Err(_) => {}
                      }
                    }
                    // Failing that, push true
                    try!(stack_true.peek_mut().set_bool_value(true));
                    return recurse(script.slice_from(index - 1), stack_true, exec_stack, depth + 1);
                  }
                  Some(val) => {
                    stack.pop();
                    exec_stack.push(!val)
                  }
                }
              }
              opcodes::Ordinary::OP_ELSE => {
                match exec_stack.last_mut() {
                  Some(ref_e) => { *ref_e = !*ref_e }
                  None => { return Err(Error::ElseWithoutIf); }
                }
              }
              opcodes::Ordinary::OP_ENDIF => {
                if exec_stack.pop().is_none() {
                  return Err(Error::EndifWithoutIf);
                }
              }
              opcodes::Ordinary::OP_VERIFY => op_verify_satisfy!(stack),
              opcodes::Ordinary::OP_TOALTSTACK => { stack.to_altstack(); }
              opcodes::Ordinary::OP_FROMALTSTACK => { try!(stack.from_altstack()); }
              opcodes::Ordinary::OP_2DROP => stack_opcode!(stack(2): require 2 drop 1; drop 2),
              opcodes::Ordinary::OP_2DUP  => stack_opcode!(stack(2): require 2 copy 2; copy 1),
              opcodes::Ordinary::OP_3DUP  => stack_opcode!(stack(3): require 3 copy 3; copy 2; copy 1),
              opcodes::Ordinary::OP_2OVER => stack_opcode!(stack(4): require 4 copy 4; copy 3),
              opcodes::Ordinary::OP_2ROT  => stack_opcode!(stack(6): require 6
                                                           perm (1, 3, 5);
                                                           perm (2, 4, 6)),
              opcodes::Ordinary::OP_2SWAP => stack_opcode!(stack(4): require 4
                                                           swap (2, 4);
                                                           swap (1, 3)),
              opcodes::Ordinary::OP_DROP  => stack_opcode!(stack(1): require 1 drop 1),
              opcodes::Ordinary::OP_DUP   => stack_opcode!(stack(1): require 1 copy 1),
              opcodes::Ordinary::OP_NIP   => stack_opcode!(stack(2): require 2 drop 2),
              opcodes::Ordinary::OP_OVER  => stack_opcode!(stack(2): require 2 copy 2),
              opcodes::Ordinary::OP_PICK => {
                let top_n = {
                  let top = stack.peek_mut();
                  try!(top.set_numeric());
                  try!(top.set_num_lo(0));
                  top.num_value().map(|n| n as usize)
                };
                stack.pop();
                match top_n {
                  Some(n) => stack_opcode!(stack(n + 1): require n + 1 copy n + 1),
                  // The stack will wind up with the 1 and nth inputs being identical
                  // with n input-dependent. I can imagine scripts which check this
                  // condition or its negation for various n to get arbitrary finite
                  // sets of allowable values. It's not clear to me that this is
                  // feasible to analyze.
                  None => { return Err(Error::Unanalyzable); }
                }
              }
              opcodes::Ordinary::OP_ROLL => {
                let top_n = {
                  let top = stack.peek_mut();
                  try!(top.set_numeric());
                  try!(top.set_num_lo(0));
                  top.num_value().map(|n| n as usize)
                };
                stack.pop();
                match top_n {
                  Some(n) => stack_opcode!(stack(n + 1): require n + 1 copy n + 1 drop n + 1),
                  // The stack will wind up reordered, so in principle I could just force
                  // the input to be zero (other n values can be converted to zero by just
                  // manually rearranging the input). The problem is if numeric bounds are
                  // later set on n. I can't analyze that.
                  None => { return Err(Error::Unanalyzable); }
                }
              }
              opcodes::Ordinary::OP_ROT  => stack_opcode!(stack(3): require 3 perm (1, 2, 3)),
              opcodes::Ordinary::OP_SWAP => stack_opcode!(stack(2): require 3 swap (1, 2)),
              opcodes::Ordinary::OP_TUCK => stack_opcode!(stack(2): require 2 copy 2; copy 1 drop 2),
              opcodes::Ordinary::OP_IFDUP => {
                let top_bool = {
                  let top = stack.peek_mut();
                  top.bool_value()
                };
                match top_bool {
                  Some(false) => { }
                  Some(true) => { stack_opcode!(stack(1): require 1 copy 1); }
                  None => {
                    let mut stack_true = stack.clone();
                    // Try pushing false and see what happens
                    if stack.peek_mut().set_bool_value(false).is_ok() {
                      match recurse(script.slice_from(index - 1), stack, exec_stack.clone(), depth + 1) {
                        Ok(res) => { return Ok(res); }
                        Err(_) => {}
                      }
                    }
                    // Failing that, push true
                    try!(stack_true.peek_mut().set_bool_value(true));
                    return recurse(script.slice_from(index - 1), stack_true, exec_stack, depth + 1);
                  }
                }
              }
              opcodes::Ordinary::OP_DEPTH => {
                let len = stack.len() as i64;
                let new_elem = stack.push_alloc(AbstractStackElem::new_unknown());
                try!(new_elem.set_numeric());
                try!(new_elem.set_num_lo(len));
              }
              opcodes::Ordinary::OP_SIZE => {
                let top = stack.peek_index();
                let new_elem = stack.push_alloc(AbstractStackElem::new_unknown());
                try!(new_elem.set_numeric());
                try!(new_elem.add_validator(Validator { args: vec![top],
                                                        check: check_op_size,
                                                        update: update_op_size }));
              }
              opcodes::Ordinary::OP_EQUAL => boolean_opcode_satisfy!(stack, binary op_equal),
              opcodes::Ordinary::OP_EQUALVERIFY => {
                boolean_opcode_satisfy!(stack, binary op_equal);
                op_verify_satisfy!(stack);
              }
              opcodes::Ordinary::OP_NOT => boolean_opcode_satisfy!(stack, unary op_not),
              opcodes::Ordinary::OP_0NOTEQUAL => boolean_opcode_satisfy!(stack, unary op_0notequal),
              opcodes::Ordinary::OP_NUMEQUAL => boolean_opcode_satisfy!(stack, binary op_numequal),
              opcodes::Ordinary::OP_NUMEQUALVERIFY => {
                boolean_opcode_satisfy!(stack, binary op_numequal);
                op_verify_satisfy!(stack);
              }
              opcodes::Ordinary::OP_NUMNOTEQUAL => boolean_opcode_satisfy!(stack, binary op_numnotequal),
              opcodes::Ordinary::OP_LESSTHAN => boolean_opcode_satisfy!(stack, binary op_numlt),
              opcodes::Ordinary::OP_GREATERTHAN => boolean_opcode_satisfy!(stack, binary op_numgt),
              opcodes::Ordinary::OP_LESSTHANOREQUAL => boolean_opcode_satisfy!(stack, binary op_numlteq),
              opcodes::Ordinary::OP_GREATERTHANOREQUAL => boolean_opcode_satisfy!(stack, binary op_numgteq),
              opcodes::Ordinary::OP_1ADD | opcodes::Ordinary::OP_1SUB | opcodes::Ordinary::OP_NEGATE |
              opcodes::Ordinary::OP_ABS | opcodes::Ordinary::OP_ADD | opcodes::Ordinary::OP_SUB |
              opcodes::Ordinary::OP_BOOLAND | opcodes::Ordinary::OP_BOOLOR |
              opcodes::Ordinary::OP_MIN | opcodes::Ordinary::OP_MAX | opcodes::Ordinary::OP_WITHIN => {
                return Err(Error::Unanalyzable);
              }
              opcodes::Ordinary::OP_RIPEMD160 => unary_opcode_satisfy!(stack, op_ripemd160),
              opcodes::Ordinary::OP_SHA1 => unary_opcode_satisfy!(stack, op_sha1),
              opcodes::Ordinary::OP_SHA256 => unary_opcode_satisfy!(stack, op_sha256),
              opcodes::Ordinary::OP_HASH160 => unary_opcode_satisfy!(stack, op_hash160),
              opcodes::Ordinary::OP_HASH256 => unary_opcode_satisfy!(stack, op_hash256),
              // Ignore code separators since we don't check signatures
              opcodes::Ordinary::OP_CODESEPARATOR => {}
              opcodes::Ordinary::OP_CHECKSIG => boolean_opcode_satisfy!(stack, binary op_checksig),
              opcodes::Ordinary::OP_CHECKSIGVERIFY => {
                boolean_opcode_satisfy!(stack, binary op_checksig);
                op_verify_satisfy!(stack);
              }
              opcodes::Ordinary::OP_CHECKMULTISIG | opcodes::Ordinary::OP_CHECKMULTISIGVERIFY => {
                let (n_keys, n_keys_hi) = {
                  let elem = stack.pop_mut();
                  try!(elem.set_numeric());
                  try!(elem.set_num_lo(0));
                  try!(elem.set_num_hi(20));
                  (elem.num_lo(), elem.num_hi())
                };
                let mut allowable_failures: i64 = 0;
                for _ in 0..n_keys {
                  let key = stack.pop_mut();
                  if key.may_be_pubkey() {
                    allowable_failures += 1;
                  }
                }
                if n_keys == n_keys_hi {
                  let (n_sigs, n_sigs_hi) = {
                    let elem = stack.pop_mut();
                    try!(elem.set_numeric());
                    try!(elem.set_num_lo(0));
                    try!(elem.set_num_hi(n_keys));
                    (elem.num_lo(), elem.num_hi())
                  };
                  allowable_failures -= n_sigs;
                  for _ in 0..n_sigs {
                    let sig = stack.pop_mut();
                    if !sig.may_be_signature() {
                      allowable_failures -= 1;
                    }
                    if allowable_failures < 0 {
                      return Err(Error::Unsatisfiable);
                    }
                    if n_sigs != n_sigs_hi { return Err(Error::Unanalyzable); }
                  }
                } else { return Err(Error::Unanalyzable); }
                // Successful multisig, push an unknown boolean
                {
                  let result = stack.push_alloc(AbstractStackElem::new_unknown());
                  try!(result.set_boolean())
                }

                // If it's a VERIFY op, assume it passed and carry on
                if op == opcodes::Ordinary::OP_CHECKMULTISIGVERIFY {
                  op_verify_satisfy!(stack);
                }
              }
            }
          }
        }
      }
      // If we finished, we are only unspendable if we have false on the stack
      match stack.peek_mut().bool_value() {
        None => stack.peek_mut().set_bool_value(true).map(|_| stack.build_initial_stack()),
        Some(true) => Ok(stack.build_initial_stack()),
        Some(false) => Err(Error::AnalyzeAlwaysReturnsFalse)
      }
    }

    let &Script(ref raw) = self;
    recurse(&raw, AbstractStack::new(), vec![], 1)
  }
}

impl Default for Script {
  fn default() -> Script { Script(vec![].into_boxed_slice()) }
}

// User-facing serialization
impl serde::Serialize for Script {
  fn serialize<S>(&self, serializer: &mut S) -> Result<(), S::Error>
      where S: serde::Serializer,
  {
    let &Script(ref raw) = self;
    for dat in raw.iter() {
      serializer.visit_char(from_digit((dat / 0x10) as usize, 16).unwrap());
      serializer.visit_char(from_digit((dat & 0x0f) as usize, 16).unwrap());
    }
  }
}

// Network serialization
impl<S: SimpleEncoder> ConsensusEncodable<S> for Script {
  #[inline]
  fn consensus_encode(&self, s: &mut S) -> Result<(), S::Error> {
    let &Script(ref data) = self;
    data.consensus_encode(s)
  }
}

impl<D: SimpleDecoder> ConsensusDecodable<D> for Script {
  #[inline]
  fn consensus_decode(d: &mut D) -> Result<Script, D::Error> {
    Ok(Script(try!(ConsensusDecodable::consensus_decode(d))))
  }
}

#[cfg(test)]
mod test {
  use std::io::IoResult;
  use serialize::hex::FromHex;

  use super::{Script, build_scriptint, read_scriptint, read_scriptbool};
  use super::{EqualVerifyFailed, NoTransaction, PopEmptyStack};
  use super::MaybeOwned::Owned;

  use network::serialize::{deserialize, serialize};
  use blockdata::opcodes;
  use blockdata::transaction::Transaction;

  fn test_tx(tx_hex: &'static str, output_hex: Vec<&'static str>) {
    let tx_hex = tx_hex.from_hex().unwrap();

    let tx: Transaction = deserialize(tx_hex.clone()).ok().expect("transaction");
    let script_pk: Vec<Script> = output_hex.iter()
                                           .map(|hex| format!("{:02x}{}", hex.len() / 2, hex))
                                           .map(|hex| (&hex[..]).from_hex().unwrap())
                                           .map(|hex| deserialize(hex.clone())
                                           .ok()
                                           .expect("scriptpk"))
                                           .collect();

    for (n, script) in script_pk.iter().enumerate() {
      let mut stack = vec![];
      assert_eq!(tx.input[n].script_sig.evaluate(&mut stack, Some((&tx, n)), None), Ok(()));
      assert_eq!(script.evaluate(&mut stack, Some((&tx, n)), None), Ok(()));
      assert!(stack.len() >= 1);
      assert_eq!(read_scriptbool(&stack.pop().unwrap()), true);
    }
  }

  #[test]
  fn script() {
    let mut comp = vec![];
    let mut script = Script::new();
    assert_eq!(script, Script(comp.into_boxed_slice()));

    // small ints
    script.push_int(1);  comp.push(82u8); assert_eq!(script, Script(comp.clone()));
    script.push_int(0);  comp.push(0u8);  assert_eq!(script, Script(comp.clone()));
    script.push_int(4);  comp.push(85u8); assert_eq!(script, Script(comp.clone()));
    script.push_int(-1); comp.push(80u8); assert_eq!(script, Script(comp.clone()));
    // forced scriptint
    script.push_scriptint(4);  comp.push_all([1u8, 4]); assert_eq!(script, Script(comp.clone()));
    // big ints
    script.push_int(17); comp.push_all([1u8, 17]); assert_eq!(script, Script(comp.clone()));
    script.push_int(10000); comp.push_all([2u8, 16, 39]); assert_eq!(script, Script(comp.clone()));
    // notice the sign bit set here, hence the extra zero/128 at the end
    script.push_int(10000000); comp.push_all([4u8, 128, 150, 152, 0]); assert_eq!(script, Script(comp.clone()));
    script.push_int(-10000000); comp.push_all([4u8, 128, 150, 152, 128]); assert_eq!(script, Script(comp.clone()));

    // data
    script.push_slice("NRA4VR".as_bytes()); comp.push_all([6u8, 78, 82, 65, 52, 86, 82]); assert_eq!(script, Script(comp.clone()));

    // opcodes 
    script.push_opcode(opcodes::all::OP_CHECKSIG); comp.push(0xACu8); assert_eq!(script, Script(comp.clone()));
    script.push_opcode(opcodes::all::OP_CHECKSIG); comp.push(0xACu8); assert_eq!(script, Script(comp.clone()));
  }

  #[test]
  fn script_serialize() {
    let hex_script = "6c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52".from_hex().unwrap();
    let script: IoResult<Script> = deserialize(hex_script.clone());
    assert!(script.is_ok());
    assert_eq!(serialize(&script.unwrap()), Ok(hex_script));
  }

  #[test]
  fn scriptint_round_trip() {
    assert_eq!(build_scriptint(-1), vec![0x81]);
    assert_eq!(build_scriptint(255), vec![255, 0]);
    assert_eq!(build_scriptint(256), vec![0, 1]);
    assert_eq!(build_scriptint(257), vec![1, 1]);
    assert_eq!(build_scriptint(511), vec![255, 1]);
    for &i in [10, 100, 255, 256, 1000, 10000, 25000, 200000, 5000000, 1000000000,
               (1 << 31) - 1, -((1 << 31) - 1)].iter() {
      assert_eq!(Ok(i), read_scriptint(&build_scriptint(i)));
      assert_eq!(Ok(-i), read_scriptint(&build_scriptint(-i)));
    }
    assert!(read_scriptint(&build_scriptint(1 << 31)).is_err());
    assert!(read_scriptint(&build_scriptint(-(1 << 31))).is_err());
  }

  #[test]
  fn script_eval_simple() {
    let mut script = Script::new();
    assert!(script.evaluate(&mut vec![], None, None).is_ok());

    script.push_opcode(opcodes::all::OP_RETURN);
    assert!(script.evaluate(&mut vec![], None, None).is_err());
  }

  #[test]
  fn script_eval_checksig_without_tx() {
    let hex_pk = "1976a914e729dea4a3a81108e16376d1cc329c91db58999488ac".from_hex().unwrap();
    let script_pk: Script = deserialize(hex_pk.clone()).ok().expect("scriptpk");
    // Should be able to check that the sig is there and pk correct
    // before needing a transaction
    assert_eq!(script_pk.evaluate(&mut vec![], None, None), Err(Error::PopEmptyStack));
    assert_eq!(script_pk.evaluate(&mut vec![Owned(vec![]), Owned(vec![])], None, None),
                                  Err(Error::EqualVerifyFailed("e729dea4a3a81108e16376d1cc329c91db589994".to_string(),
                                                                     "b472a266d0bd89c13706a4132ccfb16f7c3b9fcb".to_string())));
    // But if the signature is there, we need a tx to check it
    assert_eq!(script_pk.evaluate(&mut vec![Owned(vec![]), Owned("026d5d4cfef5f3d97d2263941b4d8e7aaa82910bf8e6f7c6cf1d8f0d755b9d2d1a".from_hex().unwrap())], None, None), Err(Error::NoTransaction));
    assert_eq!(script_pk.evaluate(&mut vec![Owned(vec![0]), Owned("026d5d4cfef5f3d97d2263941b4d8e7aaa82910bf8e6f7c6cf1d8f0d755b9d2d1a".from_hex().unwrap())], None, None), Err(Error::NoTransaction));
  }

  #[test]
  fn script_eval_pubkeyhash() {
    // nb these are both prefixed with their length in 1 byte
    let tx_hex = "010000000125d6681b797691aebba34b9d8e50f769ab1e8807e78405ae505c218cf8e1e9e1a20100006a47304402204c2dd8a9b6f8d425fcd8ee9a20ac73b619906a6367eac6cb93e70375225ec0160220356878eff111ff3663d7e6bf08947f94443845e0dcc54961664d922f7660b80c0121029fa8e8d8e3fd61183ab52f98d65500fd028a5d0a899c6bcd4ecaf1eda9eac284ffffffff0110270000000000001976a914299567077f41bc20059dc21a1eb1ef5a6a43b9c088ac00000000".from_hex().unwrap();

    let output_hex = "1976a914299567077f41bc20059dc21a1eb1ef5a6a43b9c088ac".from_hex().unwrap();

    let tx: Transaction = deserialize(tx_hex.clone()).ok().expect("transaction");
    let script_pk: Script = deserialize(output_hex.clone()).ok().expect("scriptpk");

    let mut stack = vec![];
    assert_eq!(tx.input[0].script_sig.evaluate(&mut stack, None, None), Ok(()));
    assert_eq!(script_pk.evaluate(&mut stack, Some((&tx, 0)), None), Ok(()));
    assert_eq!(stack.len(), 1);
    assert_eq!(read_scriptbool(&stack.pop().unwrap()), true);
  }


  #[test]
  fn script_eval_testnet_failure_1() {
    // OP_PUSHNUM ops weren't correct, also computed zero must be [], not [0]
    // txid dc3aad51b4b9ea1ef40755a38b0b4d6e08c72d2ac5e95b8bebe9bd319b6aed7e
    test_tx(
      "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",
      vec!["a5", "61", "0087", "9c", "9d51"]
    );
  }

  #[test]
  fn script_eval_testnet_failure_2() {
    // OP_PUSHDATA2 must read its length little-endian
    // txid c5d4b73af6eed28798473b05d2b227edd4f285069629843e899b52c2d1c165b7)
    test_tx(
      "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
      vec![
        "5279011688745387",
        "007a011488745287",
        "825587",
        "77",
        "4f9c",
        "76636768",
        "709393588893935687",
        "016e87",
        "6e7b8887",
        "9e",
        "93011587",
        "6362675168",
        "517a011588745287",
        "05feffffff0087",
        "82011a87",
        "6301ba675168",
        "0087",
        // There are 35 more ..
      ]
    );
  }

  #[test]
  fn script_eval_testnet_failure_3() {
    // For SIGHASH_SINGLE signatures, the unsigned txouts are null, that is,
    // have blank script and value **** (u64)-1 *****
    // txid 8ccc87b72d766ab3128f03176bb1c98293f2d1f85ebfaf07b82cc81ea6891fa9
    test_tx(
      "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",
      vec![
        "2102715e91d37d239dea832f1460e91e368115d8ca6cc23a7da966795abad9e3b699ac",
        "2102f71546fc597e63e2a72dadeeeb50c0ca64079a5a530cb01dd939716d41e9d480ac",
        "21031ee99d2b786ab3b0991325f2de8489246a6a3fdb700f6d0511b1d80cf5f4cd43ac",
        "210249c6a76e37c2fcd56687dde6b75bbdf72fcdeeab6fe81561a9c41ac90d9d1f48ac",
        "21035c100972ff8c572dc80eaa15a958ab99064d7c6b9e55f0e6408dec11edd4debbac",
        "2103837725cf7377d40a965f082fa6a942d39d9c2433c6d3c7bb4fa262e7d0d19defac",
      ]
    );
  }

  #[test]
  fn script_eval_testnet_failure_4() {
    // Multisig
    // txid 067cb44dcbd1e3b16eed2482cbe462a461896d4eec891935020a97158f1c100b
    test_tx(
      "01000000018feacff32dfee2218f7873c11087c65b5e7890ad2395da7d4a3e9a7b77bd23f8000000009300483045022100f76f485db0632f4a7fb3c95a5c0eae7b5d0e885f87ac4991e429b3c0f3c444ad0220155a281d7d9bb13ad013df8057a3d43f45de2702ba10b976164fbfcd4be452db014830450221008aa307b332eb0c96bf7c25c7d3c04ae75f071ed652f18dac55dedec7262aef6702203f0a46856b8b9acfac475f1056f04bf50e41aa967c401b85bea3ef20e470d27501ffffffff0100f2052a010000001976a9140550f9aedabdd2ee0424f53f26faeff1b899cc1688ac00000000",
      vec!["52210266816de738c62ad789119fdb13131faa13f588359484ca61d0515cdcc7648ecd21025fe4a325d96f109529734af5de80b961274de5720c30646c398202e5d555adca52ae"]
    );
  }

  #[test]
  fn script_eval_testnet_failure_5() {
    // Pushes in the dead half of OP_IF's should still skip over all the data (OP_PUSH[0..75]
    // txid 4d0bbf6348726a49600171033e456548a09b246829d649e77b929caf242ae6e7
    test_tx(
      "01000000017c19a5b0b84188bca5decac0dc8582f5f5ff003b1a4d705181ec5d9620c1f64600000000940048304502207d02ce76875b1b3f2b7af9e45954af1ab531da6ab3edd471aa9148f139c8bad1022100f0f85fd987e90a131f2e311acdfe212925e218ffa5cf79e84e9890c2ddbdbd450148304502207d02ce76875b1b3f2b7af9e45954af1ab531da6ab3edd471aa9148f139c8bad1022100f0f85fd987e90a131f2e311acdfe212925e218ffa5cf79e84e9890c2ddbdbd450151ffffffff0100e1f505000000001976a91403efb01790d098aef3752449a94a1dc593e527cd88ac00000000",
      vec!["6352210261411d0de63460bfed73cb871f868bc3064d1db2a09f27b2477852b1811a02ef210261411d0de63460bfed73cb871f868bc3064d1db2a09f27b2477852b1811a02ef52ae67a820080af0b0156c5dd12c820b2b1b4fbfa315d05ac5a0ea2f9a657d4c8881d0869f88a820080af0b0156c5dd12c820b2b1b4fbfa315d05ac5a0ea2f9a657d4c8881d0869f88210261411d0de63460bfed73cb871f868bc3064d1db2a09f27b2477852b1811a02efac68"]
    );
  }

  #[test]
  fn script_eval_testnet_failure_6() {
    // Pushes in the dead half of OP_IF's should still skip over all the data (OP_PUSHDATA1 2 4)
    // txid a2119ab5f90270836643665183b21e114daaa6dfdc1bdd7525e1187aa153a229
    test_tx(
      "01000000015e0767f6b58b766d922c6ddd6afc46af9d21c613754bd7cb8010adf0c9c090d2010000000401010100ffffffff0180f0fa02000000001976a914993bcb95575ecda9e7106a30f42232b8e89917c388ac00000000",
      vec!["63ff4c0778657274726f7668"]
    );
  }

  #[test]
  fn script_eval_testnet_failure_7() {
    // script_find_and_delete needs to drop the entire push operation, not just the signature data
    // txid 2c63aa814701cef5dbd4bbaddab3fea9117028f2434dddcdab8339141e9b14d1
    test_tx(
      "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",
      vec![
        "76a91419660c27383b347112e92caba64fb1d07e9f63bf88ac",
        "483045022015bd0139bcccf990a6af6ec5c1c52ed8222e03a0d51c334df139968525d2fcd20221009f9efe325476eb64c3958e4713e9eefe49bf1d820ed58d2112721b134e2a1a53037552210378d430274f8c5ec1321338151e9f27f4c676a008bdf8638d07c0b6be9ab35c71210378d430274f8c5ec1321338151e9f27f4c676a008bdf8638d07c0b6be9ab35c7152ae"
      ]
    );
  }

  #[test]
  fn script_eval_testnet_failure_8() {
    // Fencepost error in OP_CODESEPARATOR
    // txid 46224764c7870f95b58f155bce1e38d4da8e99d42dbb632d0dd7c07e092ee5aa
    test_tx(
      "01000000012432b60dc72cebc1a27ce0969c0989c895bdd9e62e8234839117f8fc32d17fbc000000004a493046022100a576b52051962c25e642c0fd3d77ee6c92487048e5d90818bcf5b51abaccd7900221008204f8fb121be4ec3b24483b1f92d89b1b0548513a134e345c5442e86e8617a501ffffffff010000000000000000016a00000000",
      vec!["24ab21038479a0fa998cd35259a2ef0a7a5c68662c1474f88ccb6d08a7677bbec7f22041ac"]
    );
  }

  #[test]
  fn script_eval_testnet_failure_9() {
    // All OP_CODESEPARATORS must be removed, not just the first one
    // txid 6327783a064d4e350c454ad5cd90201aedf65b1fc524e73709c52f0163739190
    test_tx(
      "010000000144490eda355be7480f2ec828dcc1b9903793a8008fad8cfe9b0c6b4d2f0355a900000000924830450221009c0a27f886a1d8cb87f6f595fbc3163d28f7a81ec3c4b252ee7f3ac77fd13ffa02203caa8dfa09713c8c4d7ef575c75ed97812072405d932bd11e6a1593a98b679370148304502201e3861ef39a526406bad1e20ecad06be7375ad40ddb582c9be42d26c3a0d7b240221009d0a3985e96522e59635d19cc4448547477396ce0ef17a58e7d74c3ef464292301ffffffff010000000000000000016a00000000",
      vec!["21038479a0fa998cd35259a2ef0a7a5c68662c1474f88ccb6d08a7677bbec7f22041adab21038479a0fa998cd35259a2ef0a7a5c68662c1474f88ccb6d08a7677bbec7f22041adab51"]
    );
  }

  #[test]
  fn script_eval_testnet_failure_10() {
    // In first 500 blocks, started failing after mem changes
    // txid a44d40b3a14aca3f19ccf47244ef4a70ed02d00f5d840c38756368e9a7cc24b1
    test_tx(
      "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",
      vec![
        "a9149eb21980dc9d413d8eac27314938b9da920ee53e87",
        "a91409f70b896169c37981d2b54b371df0d81a136a2c87",
        "a914e371782582a4addb541362c55565d2cdf56f649887",
      ]
    );
  }

  #[test]
  fn provably_unspendable_test() {
    // p2pk
    assert_eq!(Script::from_vec("410446ef0102d1ec5240f0d061a4246c1bdef63fc3dbab7733052fbbf0ecd8f41fc26bf049ebb4f9527f374280259e7cfa99c48b0e3f39c51347a19a5819651503a5ac".from_hex().unwrap()).is_provably_unspendable(), false);
    assert_eq!(Script::from_vec("4104ea1feff861b51fe3f5f8a3b12d0f4712db80e919548a80839fc47c6a21e66d957e9c5d8cd108c7a2d2324bad71f9904ac0ae7336507d785b17a2c115e427a32fac".from_hex().unwrap()).is_provably_unspendable(), false);
    // p2pkhash
    assert_eq!(Script::from_vec("76a914ee61d57ab51b9d212335b1dba62794ac20d2bcf988ac".from_hex().unwrap()).is_provably_unspendable(), false);
    assert_eq!(Script::from_vec("6aa9149eb21980dc9d413d8eac27314938b9da920ee53e87".from_hex().unwrap()).is_provably_unspendable(), true);
    // if return; else return
    assert_eq!(Script::from_vec("636a676a68".from_hex().unwrap()).is_provably_unspendable(), true);
    // if return; else don't
    assert_eq!(Script::from_vec("636a6768".from_hex().unwrap()).is_provably_unspendable(), false);
    // op_equal
    assert_eq!(Script::from_vec("87".from_hex().unwrap()).is_provably_unspendable(), false);
    assert_eq!(Script::from_vec("000087".from_hex().unwrap()).is_provably_unspendable(), false);
    assert_eq!(Script::from_vec("510087".from_hex().unwrap()).is_provably_unspendable(), true);
    assert_eq!(Script::from_vec("510088".from_hex().unwrap()).is_provably_unspendable(), true);
    // nested ifs
    assert_eq!(Script::from_vec("6363636363686868686800".from_hex().unwrap()).is_provably_unspendable(), true);
    // repeated op_equals
    assert_eq!(Script::from_vec("8787878787878787".from_hex().unwrap()).is_provably_unspendable(), false);
    // op_ifdup
    assert_eq!(Script::from_vec("73".from_hex().unwrap()).is_provably_unspendable(), false);
    assert_eq!(Script::from_vec("5173".from_hex().unwrap()).is_provably_unspendable(), false);
    assert_eq!(Script::from_vec("0073".from_hex().unwrap()).is_provably_unspendable(), true);
    // this is honest to god tx e411dbebd2f7d64dafeef9b14b5c59ec60c36779d43f850e5e347abee1e1a455 on mainnet
    assert_eq!(Script::from_vec("76a9144838a081d73cf134e8ff9cfd4015406c73beceb388acacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacacac
    // Real, testnet spent ones that caused me trouble
    assert_eq!(Script::from_vec("7c51880087".from_hex().unwrap()).is_provably_unspendable(), false);
    assert_eq!(Script::from_vec("9e91".from_hex().unwrap()).is_provably_unspendable(), false);
    assert_eq!(Script::from_vec("76a97ca8a687".from_hex().unwrap()).is_provably_unspendable(), false);
    assert_eq!(Script::from_vec("04010203047576a914bfbd43270c1e824c01e27386844d062d2f7518a688ad76a97614d2f7b8a37fb9b46782534078f9748f41d61a22f3877c148d4c6a901a3d87ed680478931dc9b6f0871af0ab879b69ac".from_hex().unwrap()).is_provably_unspendable(), false);
    assert_eq!(Script::from_vec("03800000".from_hex().unwrap()).is_provably_unspendable(), false);
    // This one is cool -- a 2-of-4 multisig with four pks given, only two of which are legit
    assert_eq!(Script::from_vec("522103bb52138972c48a132fc1f637858c5189607dd0f7fe40c4f20f6ad65f2d389ba42103bb52138972c48a132fc1f637858c5189607dd0f7fe40c4f20f6ad65f2d389ba45f6054ae".from_hex().unwrap()).is_provably_unspendable(), false);
    assert_eq!(Script::from_vec("64635167006867630067516868".from_hex().unwrap()).is_provably_unspendable(), false);
    // This one is on mainnet oeO
    assert_eq!(Script::from_vec("827651a0698faaa9a8a7a687".from_hex().unwrap()).is_provably_unspendable(), false);
    // gmaxwell found this one
    assert_eq!(Script::from_vec("76009f69905160a56b210378d430274f8c5ec1321338151e9f27f4c676a008bdf8638d07c0b6be9ab35c71ad6c".from_hex().unwrap()).is_provably_unspendable(), false);
  }
}