首先，目前dawn-4.1, dawn-4.2使用inline action是会报如下错误

transaction declares authority '{"actor":"hello.code","permission":"active"}', but does not have signatures for it under a provided delay of 0 ms

这个问题是4.0以后inline action的权限发生变化导致的。这个改动在eos官网的#3013这个issue讨论BM有提到过

核心是为智能合约账号添加eosio.code permission,比如hello.code调用hello.target智能合约，需要添加如下permission

cleos set account permission args.user active '{"threshold": 1,"keys": [{"key":"EOS6MRyAjQq8ud7hVNYcfnVPJqcVpscN5So8BhtHuGYqET5GDW5CV", "weight":1}],"accounts": [{"permission":{"actor":"hello.code","permission":"eosio.code"},"weight":1}]}' owner -p args.user@owner

代码

新建两个contract: hello.code和hello.target

• hello.target代码如下

   #include <eosiolib/eosio.hpp>
   #include <eosiolib/print.hpp>
   using namespace eosio;
  
   class target : public eosio::contract {
     public:
       using contract::contract;
  
       /// @abi action 
       void callme( account_name user ) {
           require_auth(user);
           print( "Call me from, ", name{user} );
       }
   };
  
   EOSIO_ABI( target, (callme) )

• hello.code的代码：

   class hello : public eosio::contract {
     public:
       using contract::contract;
       /// @abi action
       void hi( account_name from, account_name to) {
           require_auth(from);
           print( "Hello, from:", name{from}, ", to:", name{to});
           action(
               //这里{to, active}必须授权给{_self, eosio.code}
               permission_level{to, N(active)},
               //调用 hello.target合约 的'callme' action
               N(hello.target), N(callme),
               std::make_tuple(to)
            ).send();
       }
   };

  核心就是上面的红色字体的内容action(xx).send()，具体参数的含义是：

  Action(permssion_level, other_contract_account_name, method, args)

  所以:

  action(permission_level{to, N(active)},
          N(hello.target), N(callme), 
          std::make_tuple(to)
  ).send();

  这个等价于如下命令

  $cleos push action hello.target callme '["to"]' -p to

  测试

  $cleos create account eosio hello.code $KEY_PUB_1 $KEY_PUB_1
  $cleos set contract hello.code ./hello -p hello.code
  $cleos create account eosio args.user $KEY_PUB_2 $KEY_PUB_2
  $cleos create account eosio hello.target $KEY_PUB_3 $KEY_PUB_3
  $cleos create account eosio args.user1 $KEY_PUB_4 $KEY_PUB_4
  $cleos set contract hello.target ./hello.target -p hello.target
  $cleos set account permission args.user1 active '{"threshold": 1,"keys": [],"accounts": [{"permission":{"actor":"hello.code","permission":"eosio.code"},"weight":1}]}' owner -p args.user1@owner
  $cleos push action hello.code hi '["args.user", "args.user1"]' -p args.user

  源码一键实践

  https://github.com/itleaks/eos-contract/tree/master/callcontract-exp

  转载自:http://blog.csdn.net/itleaks

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