Redeemer¶

typedef struct cardano_redeemer_t cardano_redeemer_t¶

The Redeemer is an argument provided to a Plutus smart contract (script) when you are attempting to redeem a UTxO that’s protected by that script.

cardano_error_t cardano_redeemer_new(cardano_redeemer_tag_t tag, uint64_t index, cardano_plutus_data_t *data, cardano_ex_units_t *ex_units, cardano_redeemer_t **redeemer)¶

Creates and initializes a new instance of a Redeemer.

This function allocates and initializes a new instance of a cardano_redeemer_t object, representing a redeemer in the Cardano protocol. A redeemer is used to provide data for script execution in transactions. The redeemer includes a tag, an index, data, and execution units (ex_units) required for script validation.

Usage Example:

cardano_redeemer_t* redeemer = NULL;
cardano_plutus_data_t* data = ...;  // Assume data is initialized
cardano_ex_units_t* ex_units = ...;  // Assume ex_units is initialized
cardano_redeemer_tag_t tag = CARDANO_REDEEMER_TAG_SPENDING;  // Example tag
uint64_t index = 0;  // Example index

// Attempt to create a new Redeemer object
cardano_error_t result = cardano_redeemer_new(tag, index, data, ex_units, &redeemer);

if (result == CARDANO_SUCCESS)
{
  // Use the redeemer

  // Once done, ensure to clean up and release the redeemer
  cardano_redeemer_unref(&redeemer);
}
else
{
  printf("Failed to create the redeemer: %s\n", cardano_error_to_string(result));
}

// Clean up data and ex_units as necessary
cardano_plutus_data_unref(&data);
cardano_ex_units_unref(&ex_units);

Note

The caller is responsible for ensuring that both the data and ex_units parameters are valid and initialized before calling this function. Additionally, the caller must manage the memory of these parameters.

Parameters:¶

cardano_redeemer_tag_t tag¶

[in] The cardano_redeemer_tag_t representing the type of action (e.g., spending, minting, reward) that the redeemer is associated with.

uint64_t index¶

[in] The index of the transaction input this redeemer is intended for. The transaction inputs are indexed in the map order by their transaction id.

cardano_plutus_data_t *data¶

[in] A pointer to a cardano_plutus_data_t object containing the Plutus data associated with this redeemer. This data is required for script execution.

cardano_ex_units_t *ex_units¶

[in] A pointer to a cardano_ex_units_t object representing the execution units (computation and memory) allocated for this redeemer. This defines how much computational and memory resources are available for the script execution.

cardano_redeemer_t **redeemer¶

[out] On successful initialization, this will point to a newly created cardano_redeemer_t object. This object represents a “strong reference”, meaning that it is fully initialized and ready for use. The caller is responsible for managing the lifecycle of this object. Specifically, once the redeemer is no longer needed, the caller must release it by calling cardano_redeemer_unref.

Returns:¶

cardano_error_t indicating the outcome of the operation. Returns CARDANO_SUCCESS if the redeemer was successfully created, or an appropriate error code indicating the failure reason.

cardano_error_t cardano_redeemer_from_cbor(cardano_cbor_reader_t *reader, cardano_redeemer_t **redeemer)¶

Creates a cardano_redeemer_t from a CBOR reader.

This function parses CBOR data using a provided cardano_cbor_reader_t and constructs a cardano_redeemer_t object. It assumes that the CBOR reader is set up correctly and that the CBOR data corresponds to the structure expected for a redeemer.

Usage Example:

cardano_cbor_reader_t* reader = cardano_cbor_reader_new(cbor_data, data_size);
cardano_redeemer_t* redeemer = NULL;

cardano_error_t result = cardano_redeemer_from_cbor(reader, &redeemer);

if (result == CARDANO_SUCCESS)
{
  // Use the redeemer

  // Once done, ensure to clean up and release the redeemer
  cardano_redeemer_unref(&redeemer);
}
else
{
  const char* error = cardano_cbor_reader_get_last_error(reader);
  printf("Failed to decode redeemer: %s\n", error);
}

cardano_cbor_reader_unref(&reader); // Cleanup the CBOR reader

Remark

In Cardano, entities are encoded in CBOR, but CBOR allows multiple valid ways to encode the same data. The Cardano blockchain does not enforce a canonical CBOR representation, meaning that if you decode a transaction from CBOR and then re-encode it, the resulting encoding could be different. This would change the redeemer and invalidate any existing signatures. To prevent this, when a redeemer object is created using cardano_redeemer_from_cbor, it caches the original CBOR representation internally. When cardano_redeemer_to_cbor is called, it will output the cached CBOR. If the cached CBOR representation is not needed, the client can call cardano_redeemer_clear_cbor_cache after the object has been created.

Note

If the function fails, the last error can be retrieved by calling cardano_cbor_reader_get_last_error with the reader. The caller is responsible for freeing the created cardano_redeemer_t object by calling cardano_redeemer_unref when it is no longer needed.

Parameters:¶

cardano_cbor_reader_t *reader¶

[in] A pointer to an initialized cardano_cbor_reader_t that is ready to read the CBOR-encoded data.

cardano_redeemer_t **redeemer¶

[out] A pointer to a pointer of cardano_redeemer_t that will be set to the address of the newly created redeemer object upon successful decoding.

Returns:¶

A cardano_error_t value indicating the outcome of the operation. Returns CARDANO_SUCCESS if the protocol version were successfully created, or an appropriate error code if an error occurred.

cardano_error_t cardano_redeemer_to_cbor(const cardano_redeemer_t *redeemer, cardano_cbor_writer_t *writer)¶

Serializes protocol version into CBOR format using a CBOR writer.

This function serializes the given cardano_redeemer_t object using a cardano_cbor_writer_t.

Usage Example:

cardano_redeemer_t* redeemer = ...;
cardano_cbor_writer_t* writer = cardano_cbor_writer_new();

if (writer)
{
  cardano_error_t result = cardano_redeemer_to_cbor(redeemer, writer);

  if (result == CARDANO_SUCCESS)
  {
    // Use the writer's buffer containing the serialized data
  }
  else
  {
    const char* error_message = cardano_cbor_writer_get_last_error(writer);
    printf("Serialization failed: %s\n", error_message);
  }

  cardano_cbor_writer_unref(&writer);
}

cardano_redeemer_unref(&redeemer);

Remark

In Cardano, entities are encoded in CBOR, but CBOR allows multiple valid ways to encode the same data. The Cardano blockchain does not enforce a canonical CBOR representation, meaning that if you decode a transaction from CBOR and then re-encode it, the resulting encoding could be different. This would change the redeemer and invalidate any existing signatures. To prevent this, when a redeemer object is created using cardano_redeemer_from_cbor, it caches the original CBOR representation internally. When cardano_redeemer_to_cbor is called, it will output the cached CBOR. If the cached CBOR representation is not needed, the client can call cardano_redeemer_clear_cbor_cache after the object has been created.

Parameters:¶

const cardano_redeemer_t *redeemer¶

[in] A constant pointer to the cardano_redeemer_t object that is to be serialized.

cardano_cbor_writer_t *writer¶

[out] A pointer to a cardano_cbor_writer_t where the CBOR serialized data will be written. The writer must already be initialized and ready to accept the data.

Returns:¶

Returns CARDANO_SUCCESS if the serialization is successful. If the redeemer or writer is NULL, returns CARDANO_ERROR_POINTER_IS_NULL.

cardano_error_t cardano_redeemer_to_cip116_json(const cardano_redeemer_t *redeemer, cardano_json_writer_t *writer)¶

Serializes a redeemer to CIP-116 JSON.

The function writes the full JSON object, including the surrounding braces. Keys are written in the order: “tag”, “index”, “data”, “ex_units”.

Parameters:¶

const cardano_redeemer_t *redeemer¶

[in] Pointer to a valid cardano_redeemer_t.

cardano_json_writer_t *writer¶

[in] Pointer to a valid cardano_json_writer_t.

Returns:¶

CARDANO_SUCCESS On success. CARDANO_ERROR_POINTER_IS_NULL If redeemer or writer is NULL. CARDANO_ERROR_INVALID_ARGUMENT If the redeemer tag is invalid. Other Any error propagated from nested writers.

cardano_redeemer_tag_t cardano_redeemer_get_tag(const cardano_redeemer_t *redeemer)¶

Retrieves the tag associated with a redeemer.

This function fetches the tag from a given cardano_redeemer_t object. The tag specifies the type of action associated with the redeemer, such as spending, minting, or rewarding.

Usage Example:

const cardano_redeemer_t* redeemer = ...;  // Assume redeemer is already initialized
cardano_redeemer_tag_t tag = cardano_redeemer_get_tag(redeemer);

if (tag == CARDANO_REDEEMER_TAG_SPENDING)
{
    printf("Redeemer tag: Spending\n");
}

Parameters:¶

const cardano_redeemer_t *redeemer¶

[in] A constant pointer to an initialized cardano_redeemer_t object.

Returns:¶

The cardano_redeemer_tag_t indicating the type of action for the redeemer.

cardano_error_t cardano_redeemer_set_tag(cardano_redeemer_t *redeemer, cardano_redeemer_tag_t tag)¶

Sets the tag for a redeemer.

This function sets the tag of a given cardano_redeemer_t object. The tag specifies the type of action associated with the redeemer, such as spending, minting, or rewarding.

Usage Example:

cardano_redeemer_t* redeemer = ...;  // Assume redeemer is already initialized
cardano_error_t result = cardano_redeemer_set_tag(redeemer, CARDANO_REDEEMER_TAG_SPENDING);

if (result == CARDANO_SUCCESS)
{
    printf("Redeemer tag set to Spending\n");
}

Parameters:¶

cardano_redeemer_t *redeemer¶

[inout] A pointer to an initialized cardano_redeemer_t object where the tag will be set.

cardano_redeemer_tag_t tag¶

[in] A cardano_redeemer_tag_t representing the new tag to be assigned to the redeemer.

Returns:¶

cardano_error_t indicating the outcome of the operation. Returns CARDANO_SUCCESS if the tag was successfully set, or an appropriate error code indicating the failure reason.

uint64_t cardano_redeemer_get_index(const cardano_redeemer_t *redeemer)¶

Retrieves the index associated with a redeemer.

This function fetches the index from a given cardano_redeemer_t object. The index represents the position of the input or output in the transaction that the redeemer applies to.

Usage Example:

const cardano_redeemer_t* redeemer = ...;  // Assume redeemer is already initialized
uint64_t index = cardano_redeemer_get_index(redeemer);
printf("Redeemer index: %llu\n", index);

Parameters:¶

const cardano_redeemer_t *redeemer¶

[in] A constant pointer to an initialized cardano_redeemer_t object.

Returns:¶

A uint64_t representing the index of the redeemer.

cardano_error_t cardano_redeemer_set_index(cardano_redeemer_t *redeemer, uint64_t index)¶

Sets the index for the given redeemer.

This function assigns a new index to the specified cardano_redeemer_t object. The index typically refers to the position of the redeemer within a list of redeemers in a Cardano transaction.

Usage Example:

cardano_redeemer_t* redeemer = ...; // Assume redeemer is initialized
uint64_t new_index = 3; // New index to assign

cardano_error_t result = cardano_redeemer_set_index(redeemer, new_index);
if (result == CARDANO_SUCCESS)
{
  printf("Index set successfully.\n");
}
else
{
  printf("Failed to set the index.\n");
}

Parameters:¶

cardano_redeemer_t *redeemer¶

[inout] A pointer to an initialized cardano_redeemer_t object to which the index will be set.

uint64_t index¶

[in] The new index to be assigned to the redeemer.

Returns:¶

cardano_error_t indicating the outcome of the operation. Returns CARDANO_SUCCESS if the index was successfully set, or an appropriate error code indicating the failure reason, such as CARDANO_ERROR_POINTER_IS_NULL if the redeemer pointer is NULL.

cardano_plutus_data_t *cardano_redeemer_get_data(cardano_redeemer_t *redeemer)¶

Retrieves the Plutus data associated with a redeemer.

This function returns the Plutus data stored in the specified cardano_redeemer_t object. The Plutus data represents the input data provided to a Plutus script during transaction execution.

Usage Example:

const cardano_redeemer_t* redeemer = ...; // Assume redeemer is initialized
cardano_plutus_data_t* data = cardano_redeemer_get_data(redeemer);

if (data != NULL)
{
  // Use the Plutus data
  cardano_plutus_data_unref(&data); // Ensure to release the data once done
}
else
{
  printf("Failed to retrieve Plutus data or redeemer is NULL.\n");
}

Parameters:¶

cardano_redeemer_t *redeemer¶

[in] A constant pointer to an initialized cardano_redeemer_t object.

Returns:¶

A pointer to the cardano_plutus_data_t object representing the Plutus data. The returned Plutus data is a new reference, and the caller is responsible for managing its lifecycle by calling cardano_plutus_data_unref when it is no longer needed. If the redeemer is NULL, this function returns NULL.

cardano_error_t cardano_redeemer_set_data(cardano_redeemer_t *redeemer, cardano_plutus_data_t *data)¶

Sets the Plutus data for a redeemer.

This function assigns a new cardano_plutus_data_t object to the specified cardano_redeemer_t. The Plutus data represents the input provided to a Plutus script during transaction execution.

Usage Example:

cardano_redeemer_t* redeemer = ...; // Assume redeemer is already initialized
cardano_plutus_data_t* data = ...;  // Assume Plutus data is initialized

cardano_error_t result = cardano_redeemer_set_data(redeemer, data);
if (result == CARDANO_SUCCESS)
{
  // Plutus data was successfully set
}
else
{
  printf("Failed to set Plutus data: %s\n", cardano_error_to_string(result));
}

Note

The function increases the reference count of the Plutus data object, so the caller retains ownership of the data reference and must manage its lifecycle. If the Plutus data is no longer needed after assignment, the caller should release their reference by calling cardano_plutus_data_unref.

Parameters:¶

cardano_redeemer_t *redeemer¶

[inout] A pointer to an initialized cardano_redeemer_t object.

cardano_plutus_data_t *data¶

[in] A pointer to an initialized cardano_plutus_data_t object that contains the new Plutus data. This pointer can be NULL if the existing Plutus data is to be unset.

Returns:¶

cardano_error_t indicating the outcome of the operation. Returns CARDANO_SUCCESS if the Plutus data was successfully set, or an appropriate error code if an error occurred, such as CARDANO_ERROR_POINTER_IS_NULL if the redeemer is NULL.

cardano_ex_units_t *cardano_redeemer_get_ex_units(cardano_redeemer_t *redeemer)¶

Retrieves the execution units associated with a redeemer.

This function retrieves the cardano_ex_units_t object from the given cardano_redeemer_t. The execution units (ExUnits) represent the computational cost required for the execution of the Plutus script associated with the redeemer, measured in terms of memory and CPU units.

Usage Example:

const cardano_redeemer_t* redeemer = ...; // Assume redeemer is already initialized
cardano_ex_units_t* ex_units = cardano_redeemer_get_ex_units(redeemer);

if (ex_units != NULL)
{
  // Use the execution units

  // Ensure to clean up and release the ExUnits after use
  cardano_ex_units_unref(&ex_units);
}
else
{
  printf("Failed to retrieve the execution units.\n");
}

Parameters:¶

cardano_redeemer_t *redeemer¶

[in] A constant pointer to an initialized cardano_redeemer_t object from which the ExUnits will be retrieved.

Returns:¶

A pointer to the cardano_ex_units_t object representing the execution units associated with the redeemer. The returned ExUnits is a new reference, and the caller is responsible for managing the lifecycle of this object. Specifically, the caller must release the ExUnits when it is no longer needed by calling cardano_ex_units_unref. If the redeemer is NULL, the function will return NULL.

cardano_error_t cardano_redeemer_set_ex_units(cardano_redeemer_t *redeemer, cardano_ex_units_t *ex_units)¶

Sets the execution units for a redeemer.

This function assigns the specified cardano_ex_units_t object to the given cardano_redeemer_t. The execution units (ExUnits) represent the computational cost, in terms of memory and CPU, required for the execution of the Plutus script associated with the redeemer.

Usage Example:

cardano_redeemer_t* redeemer = ...; // Assume redeemer is already initialized
cardano_ex_units_t* ex_units = cardano_ex_units_new(...); // Assume ex_units is already initialized

cardano_error_t result = cardano_redeemer_set_ex_units(redeemer, ex_units);
if (result == CARDANO_SUCCESS)
{
  // The execution units have been set for the redeemer
}
else
{
  printf("Failed to set the execution units.\n");
}

// Cleanup ex_units if no longer needed
cardano_ex_units_unref(&ex_units);

Note

This function increases the reference count of the ex_units object. The caller retains ownership of their respective references and is responsible for releasing their reference to the ex_units when it is no longer needed.

Parameters:¶

cardano_redeemer_t *redeemer¶

[inout] A pointer to an initialized cardano_redeemer_t object to which the ExUnits will be set.

cardano_ex_units_t *ex_units¶

[in] A pointer to an initialized cardano_ex_units_t object representing the execution units to be assigned. This parameter must not be NULL.

Returns:¶

cardano_error_t indicating the outcome of the operation. Returns CARDANO_SUCCESS if the ExUnits were successfully set, or an appropriate error code indicating the failure reason, such as CARDANO_ERROR_POINTER_IS_NULL if either the redeemer or ex_units pointers are NULL.

void cardano_redeemer_clear_cbor_cache(cardano_redeemer_t *redeemer)¶

Clears the cached CBOR representation from a redeemer.

This function removes the internally cached CBOR data from a cardano_redeemer_t object. It is useful when you have modified the redeemer after it was created from CBOR using cardano_redeemer_from_cbor and you want to ensure that the next serialization reflects the current state of the redeemer, rather than using the original cached CBOR.

Usage Example:

// Assume redeemer was created using cardano_redeemer_from_cbor
cardano_redeemer_t* redeemer = ...;

// Modify the redeemer as needed

// Clear the CBOR cache to ensure serialization uses the updated redeemer
cardano_redeemer_clear_cbor_cache(redeemer);

// Serialize the redeemer to CBOR
cardano_cbor_writer_t* writer = cardano_cbor_writer_new();

result = cardano_redeemer_to_cbor(redeemer, writer);

if (result == CARDANO_SUCCESS)
{
  // Process the CBOR data as needed
}
else
{
  const char* error_message = cardano_cbor_writer_get_last_error(writer);
  printf("Serialization failed: %s\n", error_message);
}

// Clean up resources
cardano_cbor_writer_unref(&writer);
cardano_redeemer_unref(&redeemer);

Warning

Clearing the CBOR cache may change the binary representation of the redeemer when serialized, which can alter the redeemer and invalidate any existing signatures. Use this function with caution, especially if the transaction has already been signed or if preserving the exact CBOR encoding is important for your application.

Parameters:¶

cardano_redeemer_t *redeemer¶

[inout] A pointer to an initialized cardano_redeemer_t object from which the CBOR cache will be cleared.

void cardano_redeemer_unref(cardano_redeemer_t **redeemer)¶

Decrements the reference count of a cardano_redeemer_t object.

This function is responsible for managing the lifecycle of a cardano_redeemer_t object by decreasing its reference count. When the reference count reaches zero, the redeemer is finalized; its associated resources are released, and its memory is deallocated.

Usage Example:

cardano_redeemer_t* redeemer = cardano_redeemer_new(major, minor);

// Perform operations with the redeemer...

cardano_redeemer_unref(&redeemer);
// At this point, redeemer is NULL and cannot be used.

Note

After calling cardano_redeemer_unref, the pointer to the cardano_redeemer_t object will be set to NULL to prevent its reuse.

Parameters:¶

cardano_redeemer_t **redeemer¶

[inout] A pointer to the pointer of the redeemer object. This double indirection allows the function to set the caller’s pointer to NULL, avoiding dangling pointer issues after the object has been freed.

void cardano_redeemer_ref(cardano_redeemer_t *redeemer)¶

Increases the reference count of the cardano_redeemer_t object.

This function is used to manually increment the reference count of an cardano_redeemer_t object, indicating that another part of the code has taken ownership of it. This ensures the object remains allocated and valid until all owners have released their reference by calling cardano_redeemer_unref.

Usage Example:

// Assuming redeemer is a previously created redeemer object

cardano_redeemer_ref(redeemer);

// Now redeemer can be safely used elsewhere without worrying about premature deallocation

Note

Always ensure that for every call to cardano_redeemer_ref there is a corresponding call to cardano_redeemer_unref to prevent memory leaks.

Parameters:¶

cardano_redeemer_t *redeemer¶

A pointer to the cardano_redeemer_t object whose reference count is to be incremented.

size_t cardano_redeemer_refcount(const cardano_redeemer_t *redeemer)¶

Retrieves the current reference count of the cardano_redeemer_t object.

This function returns the number of active references to an cardano_redeemer_t object. It’s useful for debugging purposes or managing the lifecycle of the object in complex scenarios.

Usage Example:

// Assuming redeemer is a previously created redeemer object

size_t ref_count = cardano_redeemer_refcount(redeemer);

printf("Reference count: %zu\n", ref_count);

Warning

This function does not account for transitive references. A transitive reference occurs when an object holds a reference to another object, rather than directly to the cardano_redeemer_t. As such, the reported count may not fully represent the total number of conceptual references in cases where such transitive relationships exist.

Parameters:¶

const cardano_redeemer_t *redeemer¶

A pointer to the cardano_redeemer_t object whose reference count is queried. The object must not be NULL.

Returns:¶

The number of active references to the specified cardano_redeemer_t object. If the object is properly managed (i.e., every cardano_redeemer_ref call is matched with a cardano_redeemer_unref call), this count should reach zero right before the object is deallocated.

void cardano_redeemer_set_last_error(cardano_redeemer_t *redeemer, const char *message)¶

Sets the last error message for a given cardano_redeemer_t object.

Records an error message in the redeemer’s last_error buffer, overwriting any existing message. This is useful for storing descriptive error information that can be later retrieved. The message is truncated if it exceeds the buffer’s capacity.

Note

The error message is limited to 1023 characters, including the null terminator, due to the fixed size of the last_error buffer.

Parameters:¶

cardano_redeemer_t *redeemer¶

[in] A pointer to the cardano_redeemer_t instance whose last error message is to be set. If NULL, the function does nothing.

const char *message¶

[in] A null-terminated string containing the error message. If NULL, the redeemer’s last_error is set to an empty string, indicating no error.

const char *cardano_redeemer_get_last_error(const cardano_redeemer_t *redeemer)¶

Retrieves the last error message recorded for a specific redeemer.

This function returns a pointer to the null-terminated string containing the last error message set by cardano_redeemer_set_last_error for the given redeemer. If no error message has been set, or if the last_error buffer was explicitly cleared, an empty string is returned, indicating no error.

Note

The returned string points to internal storage within the object and must not be modified by the caller. The string remains valid until the next call to cardano_redeemer_set_last_error for the same redeemer, or until the redeemer is deallocated.

Parameters:¶

const cardano_redeemer_t *redeemer¶

[in] A pointer to the cardano_redeemer_t instance whose last error message is to be retrieved. If the redeemer is NULL, the function returns a generic error message indicating the null redeemer.

Returns:¶

A pointer to a null-terminated string containing the last error message for the specified redeemer. If the redeemer is NULL, “Object is NULL.” is returned to indicate the error.