EOS源码解析 创建账号的三种方式。

第一种：创建系统账号eosio的方式。

直接调用create_native_account 方法直接进行创建。并将资源设置成无限。

   void create_native_account( account_name name, const authority& owner, const authority& active, bool is_privileged = false ) {
    //create account 直接创建账号，不会做任何资源判断，因为创建的是系统账号
    db.create<account_object>([&](auto& a) {
         a.name = name;
         a.creation_date = conf.genesis.initial_timestamp;
         a.privileged = is_privileged;

         if( name == config::system_account_name ) {
            a.set_abi(eosio_contract_abi(abi_def()));
         }
      });
      db.create<account_sequence_object>([&](auto & a) {
        a.name = name;
      });

      const auto& owner_permission  = authorization.create_permission(name, config::owner_name, 0,
                                                                      owner, conf.genesis.initial_timestamp );
      const auto& active_permission = authorization.create_permission(name, config::active_name, owner_permission.id,
                                                                      active, conf.genesis.initial_timestamp );
      //初始化账号资源，但是初始化赋值只赋了resource_limits_object的owner值，其他cpu，ram,net等资源默认是-1，也就是unlimit。
      resource_limits.initialize_account(name);

      int64_t ram_delta = config::overhead_per_account_ram_bytes;
      ram_delta += 2*config::billable_size_v<permission_object>;
      ram_delta += owner_permission.auth.get_billable_size();
      ram_delta += active_permission.auth.get_billable_size();

      resource_limits.add_pending_ram_usage(name, ram_delta);
      resource_limits.verify_account_ram_usage(name);
   }



void resource_limits_manager::initialize_account(const account_name& account) {
   _db.create<resource_limits_object>([&]( resource_limits_object& bl ) {
      bl.owner = account;
   });

   _db.create<resource_usage_object>([&]( resource_usage_object& bu ) {
      bu.owner = account;
   });
}

/**
* Every account that authorizes a transaction is billed for the full size of that transaction. This object
* tracks the average usage of that account.
*/
struct resource_limits_object : public chainbase::object<resource_limits_object_type, resource_limits_object> {

      OBJECT_CTOR(resource_limits_object)

      id_type id;
      account_name owner;
      bool pending = false;

      int64_t net_weight = -1;
      int64_t cpu_weight = -1;
      int64_t ram_bytes = -1;

   };

第二种：cleos create account 方式创建账号，调用的是eosio的默认合约，但该方式在eosio 部署了eosio.system后不可用。 因为默认合约被替换掉。eosio的默认合约是来自源码提前定义好的。

具体的abi信息在：libraries/chain/eosio_contract_abi.cpp，libraries/chain/eosio_contract.cpp。

跟第一种一样，同样是将资源的使用权设置为无限。 下一次再介绍eosio默认合约的形成原理，以及调用流程。

/**
 * This method is called assuming precondition_system_newaccount succeeds a
 */
void apply_eosio_newaccount(apply_context& context) {
  auto create = context.act.data_as<newaccount>();
  try {
  context.require_authorization(create.creator);
//  context.require_write_lock( config::eosio_auth_scope );
  auto& authorization = context.control.get_mutable_authorization_manager();
 //判断公钥是否合法。
  EOS_ASSERT( validate(create.owner), action_validate_exception, "Invalid owner authority");
  EOS_ASSERT( validate(create.active), action_validate_exception, "Invalid active authority");

  auto& db = context.db;

  auto name_str = name(create.name).to_string();
 //判断account name的合法性
  EOS_ASSERT( !create.name.empty(), action_validate_exception, "account name cannot be empty" );
  EOS_ASSERT( name_str.size() <= 12, action_validate_exception, "account names can only be 12 chars long" );

  // Check if the creator is privileged
  //只有eosio才能创建eosio.为前缀的账号。
  const auto &creator = db.get<account_object, by_name>(create.creator);
  if( !creator.privileged ) {
   EOS_ASSERT( name_str.find( "eosio." ) != 0, action_validate_exception,
         "only privileged accounts can have names that start with 'eosio.'" );
  }
 //判断用户名是否存在。
  auto existing_account = db.find<account_object, by_name>(create.name);
  EOS_ASSERT(existing_account == nullptr, account_name_exists_exception,
       "Cannot create account named ${name}, as that name is already taken",
       ("name", create.name));

  const auto& new_account = db.create<account_object>([&](auto& a) {
   a.name = create.name;
   a.creation_date = context.control.pending_block_time();
  });

  db.create<account_sequence_object>([&](auto& a) {
   a.name = create.name;
  });

  for( const auto& auth : { create.owner, create.active } ){
   validate_authority_precondition( context, auth );
  }

  const auto& owner_permission = authorization.create_permission( create.name, config::owner_name, 0,
                                  std::move(create.owner) );
  const auto& active_permission = authorization.create_permission( create.name, config::active_name, owner_permission.id,
                                  std::move(create.active) );

  context.control.get_mutable_resource_limits_manager().initialize_account(create.name);

  int64_t ram_delta = config::overhead_per_account_ram_bytes;
  ram_delta += 2*config::billable_size_v<permission_object>;
  ram_delta += owner_permission.auth.get_billable_size();
  ram_delta += active_permission.auth.get_billable_size();

  context.trx_context.add_ram_usage(create.name, ram_delta);

} FC_CAPTURE_AND_RETHROW( (create) ) }

跟第一种一样，同样是将资源的使用权设置为无限。 下一次再介绍当没有部署eosio.system合约时，eosio默认合约的形成原理。

第三种：当部署eosio.system合约时，创建账号都必须使用该合约的newaccount的action。 值得一提的是用第三种方式创建时，第二种方式的apply_eosio_newaccount也会执行。

void native::newaccount( account_name   creator,
              account_name   newact
              /* no need to parse authorities
              const authority& owner,
              const authority& active*/ ) {
   //当creator 不是eosio时，需要判断创建者的资源以及低于12个字符的名字是否通过拍卖。
   if( creator != _self ) {
     auto tmp = newact >> 4;
     bool has_dot = false;

     for( uint32_t i = 0; i < 12; ++i ) {
      has_dot |= !(tmp & 0x1f);
      tmp >>= 5;
     }
     if( has_dot ) { // or is less than 12 characters
      auto suffix = eosio::name_suffix(newact);
      if( suffix == newact ) {
        name_bid_table bids(_self,_self);
        auto current = bids.find( newact );
        eosio_assert( current != bids.end(), "no active bid for name" );
        eosio_assert( current->high_bidder == creator, "only highest bidder can claim" );
        eosio_assert( current->high_bid < 0, "auction for name is not closed yet" );
        bids.erase( current );
      } else {
        eosio_assert( creator == suffix, "only suffix may create this account" );
      }
     }
   }

   user_resources_table userres( _self, newact);

   userres.emplace( newact, [&]( auto& res ) {
    res.owner = newact;
   });

   //将账号资源初始化为0，不购买资源无法进行相关动作
   set_resource_limits( newact, 0, 0, 0 );
  }