Action C API

Defines API for querying action and sending action. More...

Functions

Detailed Description

A EOS.IO action has the following abstract structure:

struct action {
  capi_name  account_name; // the contract defining the primary code to execute for code/type
  capi_name  action_name; // the action to be taken
  permission_level authorization; // the accounts and permission levels provided
  bytes data; // opaque data processed by code
};

This API enables your contract to inspect the fields on the current action and act accordingly. Example:

// Assume this action is used for the following examples:
// {
//  "code": "eos",
//  "type": "transfer",
//  "authorization": [{ "account": "inita", "permission": "active" }],
//  "data": {
//    "from": "inita",
//    "to": "initb",
//    "amount": 1000
//  }
// }

char buffer[128];
uint32_t total = read_action(buffer, 5); // buffer contains the content of the action up to 5 bytes
print(total); // Output: 5

uint32_t msgsize = action_size();
print(msgsize); // Output: size of the above action's data field


require_recipient("initc"_n); // initc account will be notified for this action

require_auth("inita"_n); // Do nothing since inita exists in the auth list
require_auth("initb"_n); // Throws an exception

print(current_time()); // Output: timestamp (in microseconds since 1970) of current block

Functions Documentation

function read_action_data

uint32_t read_action_data(
    void * msg,
    uint32_t len
)

Copy current action data to the specified location.

Copy up to length bytes of current action data to the specified location

Parameters:

msg - a pointer where up to length bytes of the current action data will be copied
len - len of the current action data to be copied, 0 to report required size

Returns:

the number of bytes copied to msg, or number of bytes that can be copied if len==0 passed

Precondition:

msg is a valid pointer to a range of memory at least len bytes long

Post

msg is filled with packed action data

function action_data_size

uint32_t action_data_size(
    void 
)

Get the length of current action's data field.

Get the length of the current action's data field. This method is useful for dynamically sized actions

Returns:

the length of the current action's data field

function require_recipient

void require_recipient(
    capi_name name
)

Add the specified account to set of accounts to be notified.

Add the specified account to set of accounts to be notified

Parameters:

name - name of the account to be verified

function require_auth

void require_auth(
    capi_name name
)

Verify specified account exists in the set of provided auths.

Verifies that name exists in the set of provided auths on a action. Throws if not found.

Parameters:

name - name of the account to be verified

function has_auth

bool has_auth(
    capi_name name
)

Verifies that name has auth.

Parameters:

name - name of the account to be verified

function require_auth2

void require_auth2(
    capi_name name,
    capi_name permission
)

Verify specified account exists in the set of provided auths.

Verifies that name exists in the set of provided auths on a action. Throws if not found.

Parameters:

name - name of the account to be verified
permission - permission level to be verified

function is_account

bool is_account(
    capi_name name
)

Verifies that Name is an existing account.

Parameters:

name - name of the account to check

function send_inline

void send_inline(
    char * serialized_action,
    size_t size
)

Send an inline action in the context of this action's parent transaction

Parameters:

serialized_action - serialized action
size - size of serialized action in bytes

Precondition:

serialized_action is a valid pointer to an array at least size bytes long

function send_context_free_inline

void send_context_free_inline(
    char * serialized_action,
    size_t size
)

/function Send an inline context free action in the context of this action's parent transaction

Parameters:

serialized_action - serialized action
size - size of serialized action in bytes

Precondition:

serialized_action is a valid pointer to an array at least size bytes long

function publication_time

uint64_t publication_time(
    void 
)

Get the publication time.

Returns the time in microseconds from 1970 of the publication_time

Returns:

the time in microseconds from 1970 of the publication_time

function current_receiver

capi_name current_receiver(
    void 
)

Get the current receiver of the action.

Get the current receiver of the action

Returns:

the account which specifies the current receiver of the action

function set_action_return_value

void set_action_return_value(
    void * return_value,
    size_t size
)

Set the action return value.

Set the action return value which will be included in the action_receipt

Parameters:

return_value - serialized return value
size - size of serialized return value in bytes

Precondition:

return_value is a valid pointer to an array at least size bytes long