当卖内存字节数按当时内存价格所值的EOS数，如果小于0.0001，则交易出错

root@iZj6cbx3duprxf6dasczbpZ:~# cleos system sellram dapp.exec 1
1483958ms thread-0   main.cpp:438                  create_action        ] result: {"binargs":"000040aa2b50ab490100000000000000"} arg: {"code":"eosio","action":"sellram","args":{"account":"dapp.exec","bytes":1}} 
Error 3050003: eosio_assert_message assertion failure
Error Details:
assertion failure with message: token amount received from selling ram is too low
pending console output:

void system_contract::sellram( account_name account, int64_t bytes ) {
      require_auth( account );
      eosio_assert( bytes > 0, "cannot sell negative byte" );

      user_resources_table  userres( _self, account );
      auto res_itr = userres.find( account );
      eosio_assert( res_itr != userres.end(), "no resource row" );
      eosio_assert( res_itr->ram_bytes >= bytes, "insufficient quota" );

      asset tokens_out;
      auto itr = _rammarket.find(S(4,RAMCORE));
      _rammarket.modify( itr, 0, [&]( auto& es ) {
          /// the cast to int64_t of bytes is safe because we certify bytes is <= quota which is limited by prior purchases
          tokens_out = es.convert( asset(bytes,S(0,RAM)), CORE_SYMBOL);
      });

      eosio_assert( tokens_out.amount > 1, "token amount received from selling ram is too low" );

当按EOS买内存时，如果所支出的EOS扣除0.5%手续费后的余额，按当时内存价格所购买的字节数小于1，则出错"must reserve a positive amount"

void system_contract::buyram( account_name payer, account_name receiver, asset quant )
   {
      require_auth( payer );
      eosio_assert( quant.amount > 0, "must purchase a positive amount" );

      auto fee = quant;
      fee.amount = ( fee.amount + 199 ) / 200; /// .5% fee (round up)
      // fee.amount cannot be 0 since that is only possible if quant.amount is 0 which is not allowed by the assert above.
      // If quant.amount == 1, then fee.amount == 1,
      // otherwise if quant.amount > 1, then 0 < fee.amount < quant.amount.
      auto quant_after_fee = quant;
      quant_after_fee.amount -= fee.amount;
      // quant_after_fee.amount should be > 0 if quant.amount > 1.
      // If quant.amount == 1, then quant_after_fee.amount == 0 and the next inline transfer will fail causing the buyram action to fail.

      INLINE_ACTION_SENDER(eosio::token, transfer)( N(eosio.token), {payer,N(active)},
         { payer, N(eosio.ram), quant_after_fee, std::string("buy ram") } );

      if( fee.amount > 0 ) {
         INLINE_ACTION_SENDER(eosio::token, transfer)( N(eosio.token), {payer,N(active)},
                                                       { payer, N(eosio.ramfee), fee, std::string("ram fee") } );
      }

      int64_t bytes_out;

      const auto& market = _rammarket.get(S(4,RAMCORE), "ram market does not exist");
      _rammarket.modify( market, 0, [&]( auto& es ) {
          bytes_out = es.convert( quant_after_fee,  S(0,RAM) ).amount;
      });

      eosio_assert( bytes_out > 0, "must reserve a positive amount" );

当按字节数买内存时，内部会先按当时内存价格计算出所需的EOS价格，如果计算出的EOS扣除0.5%手续费后的余额，按当时内存价格所购买的字节数小于1，也会出错"must reserve a positive amount"