Datum¶

typedef struct cardano_datum_t cardano_datum_t¶

Represents a piece of data attached to a UTxO that a Plutus script can read when the UTxO is being spent.

Essentially, the Datum acts as a state for that UTxO, allowing Plutus scripts to perform more complex logic based on this stored state.

cardano_error_t cardano_datum_new_data_hash(const cardano_blake2b_hash_t *hash, cardano_datum_t **datum)¶

Creates and initializes a new instance of a datum.

This function allocates and initializes a new instance of cardano_datum_t, using the provided hash. It returns an error code to indicate success or failure of the operation.

Usage Example:

cardano_blake2b_hash_t* hash = { ... };  // Assume hash is initialized here
cardano_datum_t* datum = NULL;

// Attempt to create a new datum
cardano_error_t result = cardano_datum_new_data_hash(hash, &datum);

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

  // Once done, ensure to clean up and release the datum
  cardano_datum_unref(&datum);
}

cardano_blake2b_hash_unref(&hash);

Parameters:¶

const cardano_blake2b_hash_t *hash¶

[in] A pointer to cardano_blake2b_hash_t representing the hash associated with this datum. The hash must be properly initialized before being passed to this function.

cardano_datum_t **datum¶

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

Returns:¶

CARDANO_SUCCESS if the datum was successfully created, or an appropriate error code indicating the failure reason.

cardano_error_t cardano_datum_new_data_hash_hex(const char *hex, size_t hex_size, cardano_datum_t **datum)¶

Creates a datum from a hexadecimal hash string.

This function constructs a cardano_datum_t object by interpreting the provided hexadecimal string as a hash value. It returns an error code indicating the success or failure of the operation.

Usage Example:

const char* hash_hex = "abcdef1234567890abcdef1234567890abcdef12....";
size_t hex_size = strlen(hash_hex);
cardano_datum_t* datum = NULL;

// Attempt to create a new datum from a hexadecimal hash
cardano_error_t result = cardano_datum_new_data_hash_hex(hash_hex, hex_size, &datum);

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

  // Once done, ensure to clean up and release the datum
  cardano_datum_unref(&datum);
}

Note

The function assumes that the hexadecimal string is valid and correctly formatted. Malformed input may lead to incorrect or undefined behavior.

Parameters:¶

const char *hex¶

[in] A pointer to a character array containing the hexadecimal representation of the hash.

size_t hex_size¶

[in] The size of the hexadecimal string in bytes.

cardano_datum_t **datum¶

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

Returns:¶

CARDANO_SUCCESS if the datum was successfully created, or an appropriate error code indicating the reason for failure.

cardano_error_t cardano_datum_new_data_hash_bytes(const byte_t *data, size_t data_size, cardano_datum_t **datum)¶

Creates a datum from a byte array representing a hash.

This function constructs a cardano_datum_t object by using the provided byte array as a hash value. It returns an error code indicating the success or failure of the operation.

Usage Example:

const byte_t hash_data[] = { 0xde, 0xad, 0xbe, 0xef, 0xde, 0xad, 0xbe, 0xef, 0xde, 0xad, 0xbe, 0xef ... };
size_t data_size = sizeof(hash_data);
cardano_datum_t* datum = NULL;

// Attempt to create a new datum from byte array hash
cardano_error_t result = cardano_datum_new_data_hash_bytes(hash_data, data_size, &datum);

if (result == CARDANO_SUCCESS && datum)
{
  // Use the datum

  // Once done, ensure to clean up and release the datum
  cardano_datum_unref(&datum);
}

Parameters:¶

const byte_t *data¶

[in] A pointer to the byte array containing the hash data.

size_t data_size¶

[in] The size of the byte array in bytes.

cardano_datum_t **datum¶

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

Returns:¶

CARDANO_SUCCESS if the datum was successfully created, or an appropriate error code indicating the reason for failure.

cardano_error_t cardano_datum_new_inline_data(cardano_plutus_data_t *data, cardano_datum_t **datum)¶

Creates a datum from inline data.

This function constructs a cardano_datum_t object using the provided cardano_plutus_data_t object. It returns an error code indicating the success or failure of the operation.

Usage Example:

cardano_plutus_data_t* data = ...;  // Assume data is initialized here
cardano_datum_t* datum = NULL;

// Attempt to create a new datum from inline data
cardano_error_t result = cardano_datum_new_inline_data(data, &datum);

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

  // Once done, ensure to clean up and release the datum
  cardano_datum_unref(&datum);
}

Parameters:¶

cardano_plutus_data_t *data¶

[in] A pointer to the cardano_plutus_data_t object representing the inline data.

cardano_datum_t **datum¶

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

Returns:¶

CARDANO_SUCCESS if the datum was successfully created, or an appropriate error code indicating the reason for failure.

cardano_error_t cardano_datum_from_cbor(cardano_cbor_reader_t *reader, cardano_datum_t **datum)¶

Creates a datum from a CBOR reader.

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

Usage Example:

cardano_cbor_reader_t* reader = cardano_cbor_reader_new(cbor_data, data_size);
cardano_datum_t* datum = NULL;

cardano_error_t result = cardano_datum_from_cbor(reader, &datum);

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

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

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

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_datum_t object by calling cardano_datum_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 datum data.

cardano_datum_t **datum¶

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

Returns:¶

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

cardano_error_t cardano_datum_to_cbor(const cardano_datum_t *datum, cardano_cbor_writer_t *writer)¶

Serializes a datum into CBOR format using a CBOR writer.

This function serializes the given cardano_datum_t object using a cardano_cbor_writer_t.

Usage Example:

cardano_datum_t* datum = ...;
cardano_cbor_writer_t* writer = cardano_cbor_writer_new();

if (writer)
{
  cardano_error_t result = cardano_datum_to_cbor(datum, 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_datum_unref(&datum);

Parameters:¶

const cardano_datum_t *datum¶

[in] A constant pointer to the cardano_datum_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 datum or writer is NULL, returns CARDANO_ERROR_POINTER_IS_NULL.

cardano_error_t cardano_datum_to_cip116_json(const cardano_datum_t *datum, cardano_json_writer_t *writer)¶

Serializes a datum to CIP-116 JSON.

This function serializes the datum object, which can be either inline Plutus data or a datum hash, according to the schema.

Schema (Inline): { “tag”: “datum”, “value”: { …PlutusData… } }

Schema (Hash): { “tag”: “datum_hash”, “value”: “<hex_hash>” }

Parameters:¶

const cardano_datum_t *datum¶

[in] Pointer to a valid cardano_datum_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 datum or writer is NULL. CARDANO_ERROR_MEMORY_ALLOCATION_FAILED If memory allocation fails. Other Any error propagated from nested writers.

cardano_plutus_data_t *cardano_datum_get_inline_data(cardano_datum_t *datum)¶

Retrieves the inline data associated with a datum.

This function provides access to the inline data part of a cardano_datum_t object. It returns a pointer to a cardano_plutus_data_t object representing the inline data. The caller is responsible for managing the lifecycle of this object, including releasing it with cardano_plutus_data_unref when it is no longer needed.

Usage Example:

cardano_datum_t* datum = ...;
cardano_plutus_data_t* data = cardano_datum_get_inline_data(datum);

if (data)
{
  // Use the inline data

  // Once done, ensure to clean up and release the inline data
  cardano_plutus_data_unref(&data);
}

// Clean up the datum object once done
cardano_datum_unref(&datum);

Parameters:¶

cardano_datum_t *datum¶

A constant pointer to the cardano_datum_t object from which the inline data is to be retrieved.

Returns:¶

A pointer to a cardano_plutus_data_t object containing the inline data. If the input datum is NULL, returns NULL. The caller is responsible for managing the lifecycle of this object, including releasing it with cardano_plutus_data_unref.

cardano_blake2b_hash_t *cardano_datum_get_data_hash(const cardano_datum_t *datum)¶

Retrieves the hash associated with a datum.

This function provides access to the hash part of a cardano_datum_t object. It returns a new reference to a cardano_blake2b_hash_t object representing the hash. This allows the hash to be used independently of the original datum object. The reference count of the hash object is increased by one, making it the caller’s responsibility to release it by calling cardano_blake2b_hash_unref when it is no longer needed.

Usage Example:

cardano_datum_t* original_datum = cardano_datum_new(...);
cardano_blake2b_hash_t* hash_datum = cardano_datum_get_data_hash(original_datum);

if (hash_datum)
{
  // Use the hash datum

  // Once done, ensure to clean up and release the hash datum
  cardano_blake2b_hash_unref(&hash_datum);
}
// Release the original datum after use
cardano_datum_unref(&original_datum);

Parameters:¶

const cardano_datum_t *datum¶

A constant pointer to the cardano_datum_t object from which the hash is to be retrieved.

Returns:¶

A pointer to a new cardano_blake2b_hash_t object containing the hash. If the input datum is NULL, returns NULL. The caller is responsible for managing the lifecycle of this object, including releasing it with cardano_blake2b_hash_unref.

size_t cardano_datum_get_data_hash_bytes_size(const cardano_datum_t *datum)¶

Retrieves the size of the hash bytes stored in the datum.

This function computes the size of the hash bytes stored within a cardano_datum_t object. It is particularly useful for determining the buffer size needed to store the hash bytes when retrieving them via cardano_datum_get_data_hash_bytes.

Usage Example:

cardano_datum_t* datum = cardano_datum_new(...);
size_t hash_size = cardano_datum_get_data_hash_bytes_size(datum);

if (hash_size > 0)
{
  byte_t* hash_bytes = malloc(hash_size);
  if (hash_bytes)
  {
    // Proceed to get the hash bytes
  }
}
cardano_datum_unref(&datum);

Parameters:¶

const cardano_datum_t *datum¶

[in] A constant pointer to the cardano_datum_t object from which the size of the hash bytes is to be retrieved.

Returns:¶

The size of the hash bytes. If the datum is NULL, the function returns zero.

const byte_t *cardano_datum_get_data_hash_bytes(const cardano_datum_t *datum)¶

Retrieves the byte array representation of the hash from a datum.

This function accesses the byte representation of the hash associated with a given cardano_datum_t object. It provides a direct pointer to the internal byte array representing the hash, which should not be modified or freed by the caller.

Usage Example:

cardano_datum_t* datum = cardano_datum_new(...);
const byte_t* hash_bytes = cardano_datum_get_data_hash_bytes(datum);

if (hash_bytes)
{
  // Use the hash bytes for operations like comparison or display
}

// Clean up the datum object once done
cardano_datum_unref(&datum);

Parameters:¶

const cardano_datum_t *datum¶

A constant pointer to the cardano_datum_t object from which the hash bytes are to be retrieved.

Returns:¶

A pointer to a constant byte array containing the hash data. If the input datum is NULL, returns NULL. The data remains valid as long as the datum object is not freed or modified.

size_t cardano_datum_get_data_hash_hex_size(const cardano_datum_t *datum)¶

Retrieves the size needed for the hexadecimal string representation of the datum’s hash.

This function calculates the size required to store the hexadecimal string representation of the hash associated with a cardano_datum_t object. This size includes the space needed for the null-terminator.

Usage Example:

cardano_datum_t* datum = cardano_datum_new(...);
size_t hex_size = cardano_datum_get_data_hash_hex_size(datum);
char* hex_string = malloc(hex_size);

if (hex_string)
{
  // Now use hex_string to get the hash or do other operations
  free(hex_string);
}

cardano_datum_unref(&datum);

Parameters:¶

const cardano_datum_t *datum¶

[in] A constant pointer to the cardano_datum_t object whose hash size is to be determined.

Returns:¶

The size in bytes required to store the hexadecimal representation of the hash, including the null terminator.

const char *cardano_datum_get_data_hash_hex(const cardano_datum_t *datum)¶

Retrieves the hexadecimal string representation of the hash from a datum.

This function provides access to the hexadecimal (hex) string representation of the hash associated with a given cardano_datum_t object. It returns a direct pointer to the internal hex string which should not be modified or freed by the caller.

Usage Example:

cardano_datum_t* datum = cardano_datum_new(...);
const char* hash_hex = cardano_datum_get_data_hash_hex(datum);

if (hash_hex)
{
  // Use the hash hex for operations like logging, display, or comparison
}

// Clean up the datum object once done
cardano_datum_unref(&datum);

Parameters:¶

const cardano_datum_t *datum¶

A constant pointer to the cardano_datum_t object from which the hex string of the hash is to be retrieved. The object must not be NULL.

Returns:¶

A pointer to a constant character array containing the hex representation of the hash. If the input datum is NULL, returns NULL. The data remains valid as long as the datum object is not freed or modified.

cardano_error_t cardano_datum_get_type(const cardano_datum_t *datum, cardano_datum_type_t *type)¶

Retrieves the type of the datum.

This function retrieves the type of a given cardano_datum_t object and stores it in the provided output parameter. The datum type is defined in the cardano_datum_type_t enumeration.

Usage Example:

cardano_datum_t* datum = cardano_datum_new(...);
cardano_datum_type_t type;
cardano_error_t result = cardano_datum_get_type(datum, &type);

if (result == CARDANO_SUCCESS)
{
  // Use the type
}

// Clean up the datum object once done
cardano_datum_unref(&datum);

Parameters:¶

const cardano_datum_t *datum¶

[in] A constant pointer to the cardano_datum_t object from which the type is to be retrieved. The object must not be NULL.

cardano_datum_type_t *type¶

[out] Pointer to a variable where the datum type will be stored. This variable will be set to the value from the cardano_datum_type_t enumeration.

Returns:¶

CARDANO_SUCCESS if the type was successfully retrieved, or an appropriate error code if the input is NULL or any other error occurs.

cardano_error_t cardano_datum_set_data_hash(cardano_datum_t *datum, const cardano_blake2b_hash_t *hash)¶

Sets the hash for a datum.

This function assigns a new hash to an existing cardano_datum_t object. The hash represents the identifying data for the datum. The function copies the provided hash into the datum, so the original hash object may be modified or freed after this operation without affecting the datum’s hash.

Usage Example:

cardano_datum_t* datum = ...;
cardano_blake2b_hash_t* new_hash = cardano_blake2b_compute_hash(...);

cardano_error_t result = cardano_datum_set_data_hash(datum, new_hash);

if (result == CARDANO_SUCCESS)
{
    // The hash was successfully set
}

// Clean up
cardano_datum_unref(&datum);
cardano_blake2b_hash_unref(&new_hash);

Parameters:¶

cardano_datum_t *datum¶

[inout] A pointer to the cardano_datum_t object whose hash is to be set. This object must have been previously created and not yet freed.

const cardano_blake2b_hash_t *hash¶

[in] A pointer to a cardano_blake2b_hash_t object containing the new hash to be set. This parameter must not be NULL.

Returns:¶

A cardano_error_t value indicating the outcome of the operation. Returns CARDANO_SUCCESS if the hash was successfully set. If the datum or hash is NULL, returns CARDANO_ERROR_POINTER_IS_NULL.

bool cardano_datum_equals(const cardano_datum_t *lhs, const cardano_datum_t *rhs)¶

Compares two datum objects for equality.

This function compares two datum objects to determine if they are equal.

Usage Example:

cardano_datum_t* datum1 = NULL;
cardano_datum_t* datum2 = NULL;

// Assume datum1 and datum2 are initialized properly

bool are_equal = cardano_datum_equals(datum1, datum2);

if (are_equal)
{
  printf("The datum objects are equal.\n");
}
else
{
  printf("The datum objects are not equal.\n");
}

// Clean up
cardano_datum_unref(&datum1);
cardano_datum_unref(&datum2);

Parameters:¶

const cardano_datum_t *lhs¶

[in] Pointer to the first datum object.

const cardano_datum_t *rhs¶

[in] Pointer to the second datum object.

Returns:¶

true if the datum objects are equal, false otherwise.

void cardano_datum_unref(cardano_datum_t **datum)¶

Decrements the reference count of a datum object.

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

Usage Example:

cardano_datum_t* datum = cardano_datum_new();

// Perform operations with the datum...

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

Note

After calling cardano_datum_unref, the pointer to the cardano_datum_t object will be set to NULL to prevent its reuse.

Parameters:¶

cardano_datum_t **datum¶

[inout] A pointer to the pointer of the datum 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_datum_ref(cardano_datum_t *datum)¶

Increases the reference count of the cardano_datum_t object.

This function is used to manually increment the reference count of a datum 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_datum_unref.

Usage Example:

// Assuming datum is a previously created datum object

cardano_datum_ref(datum);

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

Note

Always ensure that for every call to cardano_datum_ref there is a corresponding call to cardano_datum_unref to prevent memory leaks.

Parameters:¶

cardano_datum_t *datum¶

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

size_t cardano_datum_refcount(const cardano_datum_t *datum)¶

Retrieves the current reference count of the cardano_datum_t object.

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

Usage Example:

// Assuming datum is a previously created datum object

size_t ref_count = cardano_datum_refcount(datum);

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_datum_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_datum_t *datum¶

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

Returns:¶

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

void cardano_datum_set_last_error(cardano_datum_t *datum, const char *message)¶

Sets the last error message for a given datum object.

Records an error message in the datum’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_datum_t *datum¶

[in] A pointer to the cardano_datum_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 datum’s last_error is set to an empty string, indicating no error.

const char *cardano_datum_get_last_error(const cardano_datum_t *datum)¶

Retrieves the last error message recorded for a specific datum.

This function returns a pointer to the null-terminated string containing the last error message set by cardano_datum_set_last_error for the given datum. 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_datum_set_last_error for the same datum, or until the datum is deallocated.

Parameters:¶

const cardano_datum_t *datum¶

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

Returns:¶

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