git ssb

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  // run tx; the tx message handler
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  runTx (tx, environment = new Environment()) {
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    this.environment = environment
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    if (Buffer.isBuffer(tx) || typeof tx === 'string') {
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      tx = new Transaction(tx)
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      if (!tx.valid) {
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        throw new Error('Invalid transaction signature')
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      }
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    }
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    // look up sender
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    let fromAccount = this.environment.state.get(tx.from.toString())
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    if (!fromAccount) {
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      throw new Error('Sender account not found: ' + tx.from.toString())
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    }
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    if (fromAccount.get('nonce').gt(tx.nonce)) {
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      throw new Error(`Invalid nonce: ${fromAccount.get('nonce')} > ${tx.nonce}`)
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    }
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    fromAccount.set('nonce', fromAccount.get('nonce').add(new U256(1)))
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    let isCreation = false
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    // Special case: contract deployment
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    if (tx.to.isZero() && (tx.data.length !== 0)) {
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      console.log('This is a contract deployment transaction')
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      isCreation = true
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    }
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    // This cost will not be refunded
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    let txCost = 21000 + (isCreation ? 32000 : 0)
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    tx.data.forEach((item) => {
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      if (item === 0) {
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        txCost += 4
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      } else {
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        txCost += 68
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      }
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    })
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    if (tx.gasLimit.lt(new U256(txCost))) {
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      throw new Error(`Minimum transaction gas limit not met: ${txCost}`)
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    }
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    if (fromAccount.get('balance').lt(tx.gasLimit.mul(tx.gasPrice))) {
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      throw new Error(`Insufficient account balance: ${fromAccount.get('balance').toString()} < ${tx.gasLimit.mul(tx.gasPrice).toString()}`)
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    }
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    // deduct gasLimit * gasPrice from sender
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    fromAccount.set('balance', fromAccount.get('balance').sub(tx.gasLimit.mul(tx.gasPrice)))
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    const handler = isCreation ? this.createHandler.bind(this) : this.callHandler.bind(this)
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    let ret = handler({
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      to: tx.to,
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      from: tx.from,
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      gasLimit: tx.gasLimit - txCost,
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      value: tx.value,
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      data: tx.data
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    })
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    // refund unused gas
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    if (ret.executionOutcome === 1) {
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      fromAccount.set('balance', fromAccount.get('balance').add(tx.gasPrice.mul(ret.gasLeft.add(ret.gasRefund))))
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    }
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    // save new state?
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    return {
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      executionOutcome: ret.executionOutcome,
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      accountCreated: isCreation ? ret.accountCreated : undefined,
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      returnValue: isCreation ? undefined : ret.returnValue,
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      gasLeft: ret.gasLeft,
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      logs: ret.logs
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    }
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  }
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