/* KInterbasDB Python Package - Implementation of Array Conversion (both ways)
**
** Version 3.1
**
** The following contributors hold Copyright (C) over their respective
** portions of code (see license.txt for details):
**
** [Original Author (maintained through version 2.0-0.3.1):]
**   1998-2001 [alex]  Alexander Kuznetsov   <alexan@users.sourceforge.net>
** [Maintainers (after version 2.0-0.3.1):]
**   2001-2002 [maz]   Marek Isalski         <kinterbasdb@maz.nu>
**   2002-2004 [dsr]   David Rushby          <woodsplitter@rocketmail.com>
** [Contributors:]
**   2001      [eac]   Evgeny A. Cherkashin  <eugeneai@icc.ru>
**   2001-2002 [janez] Janez Jere            <janez.jere@void.si>
*/

/* This source file is designed to be directly included in _kiconversion.c,
** without the involvement of a header file. */

/* YYY: The conversion code should be able to implicitly transform array shape
** like this:
** - input: Python seq [1,2,3] supplied for a SMALLINT[4] DB array -> (1,2,3,NULL)
** - output: a SMALLINT[4] DB array (1,2,3,NULL) -> Python list [1,2,3]
**
** Note 2003.02.12:
** IB 6 API Guide page 153 says:
** """
**  The following array operations are not supported:
**  ...
**  - Setting individual array elements to NULL.
** """
** So I guess there's no possibility of "implicitly transforming" array shape.
*/

/******************** HARD-CODED LIMITS:BEGIN ********************/

/* MAXIMUM_NUMBER_OF_ARRAY_DIMENSIONS is an IB/Firebird engine constraint, not
** something we could overcome here in kinterbasdb. */
#define MAXIMUM_NUMBER_OF_ARRAY_DIMENSIONS 16

/******************** HARD-CODED LIMITS:END ********************/


/******************** CONVENIENCE DEFS:BEGIN ********************/

#define ARRAY_ROW_MAJOR 0
#define ARRAY_COLUMN_MAJOR 1

#define DIMENSION_SIZE_END_MARKER -1

/* YYY: VARCHAR array elements seem to be stored differently from the way
** conventional VARCHAR fields are stored.  Instead of 2 bytes at the beginning
** containing the size of the string value, array-element VARCHARs apparently
** have 2 null bytes at the end that are not used. */
#define _ADJUST_ELEMENT_SIZE_FOR_VARCHAR_IF_NECESSARY(data_type, size_of_el) \
  if (data_type == blr_varying || data_type == blr_varying2) { \
    size_of_el += 2; \
  }

/* 2003.03.30: */
#define SQLSUBTYPE_DETERMINATION_ERROR -999

/******************** CONVENIENCE DEFS:END ********************/


/******************** FUNCTION PROTOTYPES:BEGIN ********************/

/* Output functions: */
static PyObject *conv_out_array(
    CursorObject *cursor,
    ISC_QUAD *array_id,

    ISC_STATUS *status_vector, isc_db_handle db_handle, isc_tr_handle trans_handle,
    char *table_name, short table_name_length, char *field_name, short field_name_length
  );

static PyObject *conv_out_array_element(
    CursorObject *cursor,
    char *data,

    short data_type, int size_of_single_element,
    short scale,

    ISC_STATUS *status_vector, isc_db_handle db_handle, isc_tr_handle trans_handle,
    char *table_name, short table_name_length, char *field_name, short field_name_length
  );

static PyObject *_extract_db_array_buffer_to_pyseq(
    CursorObject *cursor,
    char **data_slot, short *dimension_sizes_ptr,

    /* Boilerplate parameters: */
    short data_type, int size_of_single_element,
    short scale,

    ISC_STATUS *status_vector, isc_db_handle db_handle, isc_tr_handle trans_handle,
    char *table_name, short table_name_length, char *field_name, short field_name_length
  );


/* Input functions: */
static int conv_in_array(
    PyObject *py_input, ISC_QUAD **array_id_slot,
    CursorObject *cursor,
    char *table_name, short table_name_length, char *field_name, short field_name_length
  );

static int conv_in_array_element(
    PyObject *py_input, char **data_slot,

    short data_type, short data_subtype,
    int size_of_single_element, short scale,
    PyObject *converter,

    ISC_STATUS *status_vector, isc_db_handle db_handle, isc_tr_handle trans_handle
  );

static int _extract_pyseq_to_db_array_buffer(
    PyObject *py_seq, short *dimension_sizes_ptr,

    /* Boilerplate parameters: */
    char **data_slot,

    short data_type, short data_subtype,
    int size_of_single_element, short scale,
    PyObject *converter,

    ISC_STATUS *status_vector, isc_db_handle db_handle, isc_tr_handle trans_handle
  );


/* Functions common to both input and output: */
ISC_ARRAY_DESC *_populate_array_descriptor(
    /* These strings aren't null-terminated: */
    char *sqlvar_table_name, short sqlvar_table_name_length,
    char *sqlvar_field_name, short sqlvar_field_name_length,

    /* Boilerplate params: */
    ISC_STATUS *status_vector, isc_db_handle db_handle, isc_tr_handle trans_handle
  );


short *_extract_dimensions_sizes(
    ISC_ARRAY_DESC *desc,
    /* output param: */
    int *total_number_of_elements
  );

/* 2003.03.30: */
short _determine_sqlsubtype_for_array(
    ISC_STATUS *status_vector, isc_db_handle db_handle, isc_tr_handle trans_handle,
    char *table_name, short table_name_length, char *field_name, short field_name_length
  );

#ifdef KIDB_DEBUGGERING
  void dump_array_descriptor(ISC_ARRAY_DESC *desc);
#endif /* KIDB_DEBUGGERING */

/******************** FUNCTION PROTOTYPES:END ********************/


/******************** INPUT FUNCTIONS:BEGIN ********************/

#define _CONV_IN_ARRAY_MEMORY_ERROR_IF_NULL(pointer) \
  if (pointer == NULL) { \
    PyErr_NoMemory(); \
    goto CONV_IN_ARRAY_CLEANUP; \
  }

#define _CONV_IN_ARRAY_GENERIC_ERROR_IF_NECESSARY(status_vector) \
  if ( DB_API_ERROR(status_vector) ) { \
    goto CONV_IN_ARRAY_GENERIC_ERROR; \
  }

static int conv_in_array(
    PyObject *py_input,
    ISC_QUAD **array_id_slot,
    CursorObject *cursor,
    char *table_name, short table_name_length, char *field_name, short field_name_length
  )
{
  int status = INPUT_OK;
  ISC_ARRAY_DESC *desc;
  short *dimensions = NULL;
  unsigned short number_of_dimensions;
  int total_number_of_elements = 0;

  short data_type = -1;
  unsigned short size_of_single_element;

  char *source_buf = NULL, *source_buf_walker;
  ISC_LONG source_buf_size;

  ISC_STATUS *status_vector = cursor->status_vector;
  isc_db_handle db_handle = cursor->connection->db_handle;
  isc_tr_handle trans_handle = CON_GET_TRANS_HANDLE(cursor->connection); /* 2003.10.15a:OK */

  PyObject *converter = NULL;
  short data_subtype = -1;

  /* Read the database array descriptor for this field. */
  desc = _populate_array_descriptor(
      table_name, table_name_length,
      field_name, field_name_length,

      status_vector, db_handle, trans_handle
    );
  if (desc == NULL) {
    /* The _populate_array_descriptor function will already have set exception. */
    status = INPUT_ERROR;
    goto CONV_IN_ARRAY_CLEANUP;
  }

  data_type = desc->array_desc_dtype;
  number_of_dimensions = desc->array_desc_dimensions;

  size_of_single_element = desc->array_desc_length;
  _ADJUST_ELEMENT_SIZE_FOR_VARCHAR_IF_NECESSARY(data_type, size_of_single_element);

  /* Populate the short-array named dimensions.  (The function also sets
  ** total_number_of_elements to its appropriate value.) */
  dimensions = _extract_dimensions_sizes(desc, &total_number_of_elements);
  _CONV_IN_ARRAY_MEMORY_ERROR_IF_NULL(dimensions);
  assert(total_number_of_elements > 0);

  /* Validate the incoming Python sequence to ensure that its shape matches
  ** that defined by the database array descriptor for this field. */
  source_buf_size = size_of_single_element * total_number_of_elements;
  source_buf = kimem_main_malloc(source_buf_size);
  _CONV_IN_ARRAY_MEMORY_ERROR_IF_NULL(source_buf);
  source_buf_walker = source_buf;

  assert (data_type != -1);
  data_subtype = _determine_sqlsubtype_for_array(
      status_vector, db_handle, trans_handle,
      table_name, table_name_length, field_name, field_name_length
    );
  if (data_subtype == SQLSUBTYPE_DETERMINATION_ERROR) { goto CONV_IN_ARRAY_CLEANUP; }

  { short scale = desc->array_desc_scale;

    /* Find the dynamic type translation converter (if any) for this array's type. */
    converter = cursor_get_in_converter(cursor, data_type, data_subtype, scale, TRUE);
    if (converter == NULL) { goto CONV_IN_ARRAY_CLEANUP; }
    /* At this point, converter is either a Python callable, if there was a
    ** registered converter for this array's element type, or Py_None if there
    ** was not. */

    status = _extract_pyseq_to_db_array_buffer(
        py_input, dimensions,

        /* For conversion: */
        &source_buf_walker,

        data_type, data_subtype,
        size_of_single_element, scale,
        converter,

        status_vector, db_handle, trans_handle
      );

    if (status != INPUT_OK) {
      goto CONV_IN_ARRAY_CLEANUP;
    }
  }

  /* Successful completion requires the entire buffer to have been filled: */
  assert (source_buf_walker - source_buf == source_buf_size);

  _ADJUST_ELEMENT_SIZE_FOR_VARCHAR_IF_NECESSARY(data_type, size_of_single_element);

  /* Call isc_array_put_slice to store the incoming value in the database.
  ** A NULL array id tells isc_array_put_slice to "create or replace" the
  ** existing array in the database. */
  assert (*array_id_slot == NULL);
  { ISC_QUAD *array_id;
    array_id = *array_id_slot = kimem_main_malloc(sizeof(ISC_QUAD));
    _CONV_IN_ARRAY_MEMORY_ERROR_IF_NULL(array_id);
    /* "Nullify" the array id: */
    /* 2003.01.25:  In FB 1.5a5, isc_quad_high/isc_quad_low no longer work,
    ** but gds_quad_high/gds_quad_low work with both 1.0 and 1.5a5. */
    array_id->gds_quad_high = 0;
    array_id->gds_quad_low = 0;

    ENTER_DB
    isc_array_put_slice(
        status_vector,
        &db_handle,
        &trans_handle,
        array_id,
        desc,
        source_buf,
        &source_buf_size
      );
    LEAVE_DB
    _CONV_IN_ARRAY_GENERIC_ERROR_IF_NECESSARY(status_vector);
  }

  /* array_id_slot (a pointer to a pointer passed in by the caller) is freshly
  ** initialized by isc_array_put_slice.  In effect, it is "passed back" to the
  ** caller, so that it can be accessed in the XSQLVAR when the statement is
  ** executed. */

  /* We've stored the array successfully; now clean up. */
  goto CONV_IN_ARRAY_CLEANUP;

CONV_IN_ARRAY_GENERIC_ERROR:
  raise_sql_exception( OperationalError, "Array input conversion: ",
      status_vector
    );
  status = INPUT_ERROR;
  /* Fall through to generic cleanup. */

CONV_IN_ARRAY_CLEANUP:
  if (desc != NULL)                     kimem_main_free(desc);

  if (dimensions != NULL)               kimem_main_free(dimensions);
  if (source_buf != NULL)               kimem_main_free(source_buf);

  if (status != INPUT_OK && *array_id_slot != NULL) {
    kimem_main_free(*array_id_slot);
    *array_id_slot = NULL;
  }

  return status;
} /* conv_in_array */

/*****************************************************************************/


#define CONV_IN_ARRAY_ELEMENT_TRY_INPUT_CONVERSION(conversion_code) \
  TRY_INPUT_CONVERSION( (conversion_code), CONV_IN_ARRAY_ELEMENT_FAIL );

/* A "standard" DB type code is like SQL_LONG rather than blr_long. */
#define CONV_IN_ARRAY_ELEMENT_CONVERT_INTEGER_TYPE(standard_db_type_code) \
  CONV_IN_ARRAY_ELEMENT_TRY_INPUT_CONVERSION( \
    conv_in_internal_integer_types_array(py_input_converted, data_slot, \
        standard_db_type_code, data_subtype, scale \
      ) \
    );

static int conv_in_array_element(
    PyObject *py_input, char **data_slot,

    short data_type, short data_subtype,
    int size_of_single_element, short scale,
    PyObject *converter,

    ISC_STATUS *status_vector, isc_db_handle db_handle, isc_tr_handle trans_handle
  )
{
  int status;
  PyObject *py_input_converted;

  assert (py_input != NULL);

  py_input_converted = dynamically_type_convert_input_obj_if_necessary(
      py_input,
      TRUE, /* it IS an array element */
      data_type, data_subtype, scale,
      converter
    );
  if (py_input_converted == NULL) { goto CONV_IN_ARRAY_ELEMENT_FAIL; }

  switch (data_type) {

  case blr_text:
  case blr_text2:
    CONV_IN_ARRAY_ELEMENT_TRY_INPUT_CONVERSION(
        conv_in_text_array(data_slot, size_of_single_element, ' ')
      );
    break;

  case blr_varying:
  case blr_varying2:
    CONV_IN_ARRAY_ELEMENT_TRY_INPUT_CONVERSION(
        conv_in_text_array(data_slot, size_of_single_element,
            /* Unlike normal VARCHAR field values, VARCHAR array elements are
            ** stored at a constant length, but padded with null characters: */
            '\0'
          )
      );
    break;

  case blr_short:
    CONV_IN_ARRAY_ELEMENT_CONVERT_INTEGER_TYPE(SQL_SHORT);
    break;

  case blr_long:
    CONV_IN_ARRAY_ELEMENT_CONVERT_INTEGER_TYPE(SQL_LONG);
    break;

#ifdef INTERBASE6_OR_LATER
  case blr_int64:
    CONV_IN_ARRAY_ELEMENT_CONVERT_INTEGER_TYPE(SQL_INT64);
    break;
#endif /* INTERBASE6_OR_LATER */

  case blr_float:
    CONV_IN_ARRAY_ELEMENT_TRY_INPUT_CONVERSION(
        conv_in_float_array(py_input_converted, data_slot)
      );
    break;

  case blr_double:
  case blr_d_float:
    CONV_IN_ARRAY_ELEMENT_TRY_INPUT_CONVERSION(
        conv_in_double_array(py_input_converted, data_slot)
      );
    break;

  case blr_timestamp:
    CONV_IN_ARRAY_ELEMENT_TRY_INPUT_CONVERSION(
        conv_in_timestamp_array(py_input_converted, data_slot)
      );
    break;

#ifdef INTERBASE6_OR_LATER
  case blr_sql_date:
    CONV_IN_ARRAY_ELEMENT_TRY_INPUT_CONVERSION(
        conv_in_date_array(py_input_converted, data_slot)
      );
    break;

  case blr_sql_time:
    CONV_IN_ARRAY_ELEMENT_TRY_INPUT_CONVERSION(
        conv_in_time_array(py_input_converted, data_slot)
      );
    break;
#endif /* INTERBASE6_OR_LATER */

  /* Currently, none of the following types is supported, because it's not clear
  ** how one would create such a field via SQL DDL.  As far as I can tell, this
  ** makes the types below useless for a client interface such as kinterbasdb: */
  case blr_quad:
  case blr_blob:
  case blr_blob_id:
    raise_exception( NotSupportedError,
        "kinterbasdb does not support arrays of arrays or arrays of blobs"
        " because it's not clear how one would create such a field via SQL."
      );
    goto CONV_IN_ARRAY_ELEMENT_FAIL;

  /* NULL-terminated string: */
  case blr_cstring:
  case blr_cstring2:
    raise_exception( NotSupportedError,
        "kinterbasdb does not support blr_cstring arrays because it's not clear"
        " how one would create such a field via SQL, or even why it would be"
        " desirable (in light of the existence of CHAR and VARCHAR arrays)."
      );
    goto CONV_IN_ARRAY_ELEMENT_FAIL;

  default:
    raise_exception( NotSupportedError,
        "Incoming conversion of array element of this type not supported "
        KIDB_REPORT " " KIDB_HOME_PAGE
      );
    goto CONV_IN_ARRAY_ELEMENT_FAIL;
  } /* end of switch on data_type */

  /* Success: */
  status = INPUT_OK;
  goto CONV_IN_ARRAY_ELEMENT_CLEANUP;

 CONV_IN_ARRAY_ELEMENT_FAIL:
  status = INPUT_ERROR;
 CONV_IN_ARRAY_ELEMENT_CLEANUP:
  Py_XDECREF(py_input_converted);

  return status;
} /* conv_in_array_element */

/*****************************************************************************/

#define _EXTRACT_SEQ_GET_SEQ_EL_WITH_EXCEPTION(seq, index, target) \
    target = PySequence_GetItem(seq, index); \
    if (target == NULL) { \
      raise_exception(InterfaceError, "Array input conversion:" \
          " could not retrieve element of input sequence" \
        ); \
      return INPUT_ERROR; \
    }


static int _extract_pyseq_to_db_array_buffer(
    /* For validation: */
    PyObject *py_seq, short *dimension_sizes_ptr,

    /* For conversion: */
    char **data_slot,

    short data_type, short data_subtype,
    int size_of_single_element, short scale,

    PyObject *converter,

    ISC_STATUS *status_vector, isc_db_handle db_handle, isc_tr_handle trans_handle
  )
{
  int i;
  int py_seq_len;

  int required_length_of_this_dimension = (int) *dimension_sizes_ptr;
  assert (required_length_of_this_dimension > 0);

  if ( !PySequence_Check(py_seq) || PyString_Check(py_seq) ) {
    #if PYTHON_2_2_OR_LATER
    {
      PyObject *input_py_obj_type = PyObject_Type(py_seq);
      PyObject *input_py_obj_type_repr = PyObject_Repr(input_py_obj_type);
      PyObject *err_msg = PyString_FromFormat(
          "Array input conversion: type error:"
          " input sequence must be Python sequence other than string, not"
          " %s",
          PyString_AsString(input_py_obj_type_repr)
        );

      raise_exception( InterfaceError, PyString_AS_STRING(err_msg) );

      Py_DECREF(input_py_obj_type);
      Py_DECREF(input_py_obj_type_repr);
      Py_DECREF(err_msg);
    }
    #else /* not PYTHON_2_2_OR_LATER */
      raise_exception(InterfaceError, "Array input conversion: type error:"
          " input sequence must be Python sequence other than string."
        );
    #endif /* PYTHON_2_2_OR_LATER */

    return INPUT_ERROR;
  } /* if not appropriate seq */
  py_seq_len = PySequence_Length(py_seq);

  if (py_seq_len != required_length_of_this_dimension) {
    char *base_err_msg = "Array input conversion: the input sequence is not"
      " appropriately shaped";
    #if PYTHON_2_2_OR_LATER
    {
      PyObject *err_msg = PyString_FromFormat("%s (current dimension requires"
          " input sequences of exactly %d elements, but actual input sequence"
          " has%s%d elements).",
          base_err_msg, required_length_of_this_dimension,
          (py_seq_len < required_length_of_this_dimension ? " only " : ""),
          py_seq_len
        );
      raise_exception( InterfaceError, PyString_AS_STRING(err_msg) );
      Py_DECREF(err_msg);
    }
    #else /* not PYTHON_2_2_OR_LATER */
      raise_exception( InterfaceError, base_err_msg );
    #endif /* PYTHON_2_2_OR_LATER */

    return INPUT_ERROR;
  } else {
    short *next_dimension_size_ptr = dimension_sizes_ptr + 1;
    if (*next_dimension_size_ptr == DIMENSION_SIZE_END_MARKER) {
      /* py_seq contains "leaf objects" (input values rather than subsequences).
      ** Convert each "leaf object" from its Python repr to its DB-internal
      ** repr; store the result in the raw array source buffer. */
      int conv_status_for_this_value;

      for (i = 0; i < py_seq_len; i++) {
        PyObject *py_input;
        _EXTRACT_SEQ_GET_SEQ_EL_WITH_EXCEPTION(py_seq, i, py_input);

        /* MEAT: */
        conv_status_for_this_value = conv_in_array_element(
            py_input, data_slot,

            data_type, data_subtype,
            size_of_single_element, scale,
            converter,

            status_vector, db_handle, trans_handle
          );

        Py_DECREF(py_input); /* PySequence_GetItem creates new ref; discard it. */

        if (conv_status_for_this_value == INPUT_ERROR) {
          /* The conversion function will already have set an exception. */
          return INPUT_ERROR;
        }

        /* Move the raw-array-soure-buffer pointer to the next slot. */
        *data_slot += size_of_single_element;
      } /* end of convert-each-value loop */
    } else {
      /* py_seq does NOT contain "leaf objects", so recursively validate each
      ** sub-element of py_seq. */
      for (i = 0; i < py_seq_len; i++) {
        int status_for_this_sub_el;
        PyObject *sub_el;

        _EXTRACT_SEQ_GET_SEQ_EL_WITH_EXCEPTION(py_seq, i, sub_el);

        /* MEAT: */
        status_for_this_sub_el = _extract_pyseq_to_db_array_buffer(
            sub_el,
            next_dimension_size_ptr,

            data_slot,

            data_type, data_subtype,
            size_of_single_element, scale,
            converter,

            status_vector, db_handle, trans_handle
          );

        Py_DECREF(sub_el); /* PySequence_GetItem creates new ref; discard it. */

        if (status_for_this_sub_el == INPUT_ERROR) {
          return INPUT_ERROR;
        }
      } /* end of validate-each-subelement loop */
    } /* end of this-sequence-contains-leaves if block */
  } /* end of this-sequence-was-appropriate length if block */

  return INPUT_OK;
} /* _extract_pyseq_to_db_array_buffer */


/******************** INPUT FUNCTIONS:END ********************/


/******************** OUTPUT FUNCTIONS:BEGIN ********************/

#define _CONV_OUT_ARRAY_MEMORY_ERROR_IF_NULL(pointer) \
  if (pointer == NULL) { \
    PyErr_NoMemory(); \
    goto CONV_OUT_ARRAY_CLEANUP; \
  }

#define _CONV_OUT_ARRAY_GENERIC_ERROR_IF_NECESSARY(status_vector) \
  if ( DB_API_ERROR(status_vector) ) { \
    goto CONV_OUT_ARRAY_GENERIC_ERROR; \
  }

static PyObject *conv_out_array(
    CursorObject *cursor,
    ISC_QUAD *array_id,
    ISC_STATUS *status_vector, isc_db_handle db_handle, isc_tr_handle trans_handle,
    char *table_name, short table_name_length, char *field_name, short field_name_length
  )
{
  /* YYY:I think that arrays are always stored in row-major order inside the DB,
  ** and are also retrieved that way unless the app requests otherwise (via
  ** desc->array_desc_flags).  I'm not sure, though; perhaps I need to handle
  ** cases where:
  **   desc->array_desc_flags == ARRAY_COLUMN_MAJOR
  */
  PyObject *result = NULL;

  char *output_buf = NULL, *output_buf_walker;
  ISC_LONG output_buf_size = -1;
  unsigned short size_of_single_element = 0;
  short scale = -1;
  short data_type = -1;

  ISC_ARRAY_DESC *desc;

  unsigned short number_of_dimensions;
  short *dimensions = NULL;

  int total_number_of_elements; /* Will be set later. */

  desc = _populate_array_descriptor(
      table_name, table_name_length,
      field_name, field_name_length,

      status_vector, db_handle, trans_handle
    );
  _CONV_OUT_ARRAY_MEMORY_ERROR_IF_NULL(desc);

  #ifdef KIDB_DEBUGGERING
    dump_array_descriptor(desc);
  #endif /* KIDB_DEBUGGERING */

  number_of_dimensions = desc->array_desc_dimensions;
  assert (number_of_dimensions >= 1);

  data_type = desc->array_desc_dtype;

  size_of_single_element = desc->array_desc_length;

  _ADJUST_ELEMENT_SIZE_FOR_VARCHAR_IF_NECESSARY(data_type, size_of_single_element);

  scale = desc->array_desc_scale;

  /* Populate the short-array named dimensions.  (The function also sets
  ** total_number_of_elements to its appropriate value.) */
  dimensions = _extract_dimensions_sizes(desc, &total_number_of_elements);
  _CONV_OUT_ARRAY_MEMORY_ERROR_IF_NULL(dimensions);
  assert(total_number_of_elements > 0);

  output_buf_size = size_of_single_element * total_number_of_elements;

  output_buf = kimem_main_malloc(output_buf_size);
  _CONV_OUT_ARRAY_MEMORY_ERROR_IF_NULL(output_buf);
  output_buf_walker = output_buf;

  ENTER_DB
  isc_array_get_slice(status_vector,
      &db_handle,
      &trans_handle,
      array_id,
      desc,
      (void *) output_buf,
      &output_buf_size
    );
  LEAVE_DB
  _CONV_OUT_ARRAY_GENERIC_ERROR_IF_NECESSARY(status_vector);

  /* The MEAT: */
  result = _extract_db_array_buffer_to_pyseq(
      cursor,
      &output_buf_walker, /* pointer to pointer to the first element of the output buffer */
      dimensions, /* pointer to array containing the element counts for successive dimensions */

      /* Boilerplate parameters: */
      data_type, size_of_single_element, scale,
      /* Pass through utility stuff from above: */
      status_vector, db_handle, trans_handle,
      table_name, table_name_length, field_name, field_name_length
    );
  /* 2003.03.30: */
  if (result == NULL) {
    if (!PyErr_Occurred()) { PyErr_NoMemory(); }
    goto CONV_OUT_ARRAY_CLEANUP;
  }

  assert (output_buf_walker - output_buf == output_buf_size);

  /* We've retrieved the array successfully; now clean up. */
  goto CONV_OUT_ARRAY_CLEANUP;

CONV_OUT_ARRAY_GENERIC_ERROR:
  raise_sql_exception( OperationalError, "Array output conversion: ",
      status_vector
    );
  if (result != NULL) {
    Py_DECREF(result);
    result = NULL;
  }
  /* Fall though to the rest of the cleanup. */

CONV_OUT_ARRAY_CLEANUP:
  if (desc != NULL)                     kimem_main_free(desc);

  if (dimensions != NULL)               kimem_main_free(dimensions);
  if (output_buf != NULL)               kimem_main_free(output_buf);

  /* If there was a problem, the code that ordered the jump to
  ** CONV_OUT_ARRAY_CLEANUP is required to have set a Python exception, and to
  ** have set the PyObject *result to NULL (after having deallocated it, if
  ** necessary).
  ** For these reasons, at this stage we can simply return result, regardless
  ** of its value. */
  return result;
} /* conv_out_array */

/*****************************************************************************/

static PyObject *_extract_db_array_buffer_to_pyseq(
    CursorObject *cursor,
    char **data_slot, short *dimension_sizes_ptr,

    /* Boilerplate parameters (capitalized to differentiate them): */
    short data_type, int size_of_single_element,
    short scale,
    ISC_STATUS *status_vector, isc_db_handle db_handle, isc_tr_handle trans_handle,
    char *table_name, short table_name_length, char *field_name, short field_name_length
  )
{
  short elCount = *dimension_sizes_ptr;
  short *next_dimension_size_ptr = dimension_sizes_ptr + 1;
  PyObject *seq = PyList_New(elCount);
  short i;
  if (seq == NULL) {
    PyErr_NoMemory();
    goto _EXTRACT_DB_ARRAY_BUFFER_TO_PYSEQ_FAILURE;
  }

  if (*next_dimension_size_ptr == DIMENSION_SIZE_END_MARKER) {
    for (i = 0; i < elCount; i++) {
      PyObject *val = conv_out_array_element(
          cursor,
          *data_slot,

          data_type, size_of_single_element,
          scale,
          status_vector, db_handle, trans_handle,
          table_name, table_name_length, field_name, field_name_length
        );
      if (val == NULL) {
        goto _EXTRACT_DB_ARRAY_BUFFER_TO_PYSEQ_FAILURE;
      }

      /* Move the raw-array-desination-buffer pointer to the next slot. */
      *data_slot += size_of_single_element;

      /* PyList_SET_ITEM steals ref to val; no need to DECREF. */
      PyList_SET_ITEM(seq, i, val);
    }
  } else { /* not the ultimate nestLev */
    for (i = 0; i < elCount; i++ ) {
      /* Recursive call: */
      PyObject *subList = _extract_db_array_buffer_to_pyseq(
          cursor,
          data_slot,
          next_dimension_size_ptr,

          /* Boilerplate parameters (capitalized to differentiate them): */
          data_type, size_of_single_element, scale,
          status_vector, db_handle, trans_handle,
          table_name, table_name_length, field_name, field_name_length
        );
      if (subList == NULL) {
        goto _EXTRACT_DB_ARRAY_BUFFER_TO_PYSEQ_FAILURE;
      }

      /* PyList_SET_ITEM steals ref to subList; no need to DECREF. */
      PyList_SET_ITEM(seq, i, subList);
    }
  } /* end of block: if/else ultimate_nest_level */

  assert (PyList_GET_SIZE(seq) == elCount);
  return seq;

_EXTRACT_DB_ARRAY_BUFFER_TO_PYSEQ_FAILURE:
  Py_XDECREF(seq);
  return NULL;
} /* _extract_db_array_buffer_to_pyseq */

/*****************************************************************************/


static PyObject *conv_out_array_element(
    CursorObject *cursor,
    char *data,

    short data_type, int size_of_single_element,

    short scale,

    ISC_STATUS *status_vector, isc_db_handle db_handle, isc_tr_handle trans_handle,
    char *table_name, short table_name_length, char *field_name, short field_name_length
  )
{
  PyObject *result = NULL;
  PyObject *converter = NULL;

  short data_subtype = _determine_sqlsubtype_for_array(
      status_vector, db_handle, trans_handle,
      table_name, table_name_length, field_name, field_name_length
    );
  if (data_subtype == SQLSUBTYPE_DETERMINATION_ERROR) {
    return NULL;
  }

  converter = cursor_get_out_converter(cursor, data_type, data_subtype, scale, TRUE);
  /* cursor_get_out_converter returns NULL on error, borrowed reference to
  ** Py_None if there was no converter. */
  if (converter == NULL) { return NULL; }

  switch (data_type) {

  case blr_text:
  case blr_text2:
    result = conv_out_char(data, size_of_single_element);
    break;

  case blr_varying:
  case blr_varying2:
    { /* YYY: VARCHAR array elements seem to be stored differently from the way
      ** conventional VARCHAR fields are stored (see documentary note about
      ** _ADJUST_ELEMENT_SIZE_FOR_VARCHAR_IF_NECESSARY). */
      int len_before_null = strlen(data);
      result = conv_out_char(data,
          (len_before_null <= size_of_single_element ? len_before_null : size_of_single_element)
        );
    }

    break;

  /* NULL-terminated string: */
  case blr_cstring:
  case blr_cstring2:
    result = PyString_FromString(data);
    break;

  case blr_short:
    result = conv_out_short_long(data,
        SQL_SHORT,
        IS_FIXED_POINT__ARRAY_EL(data_type, data_subtype, scale),
        scale
      );
    break;

  case blr_long:
    result = conv_out_short_long(data,
        SQL_LONG,
        IS_FIXED_POINT__ARRAY_EL(data_type, data_subtype, scale),
        scale
      );
    break;

#ifdef INTERBASE6_OR_LATER
  case blr_int64:
    result = conv_out_int64(data,
        IS_FIXED_POINT__ARRAY_EL(data_type, data_subtype, scale),
        scale
      );
    break;
#endif /* INTERBASE6_OR_LATER */

  case blr_float:
    result = conv_out_float(data);
    break;

  case blr_double:
  case blr_d_float:
    result = conv_out_double(data);
    break;

  case blr_timestamp:
    result = conv_out_timestamp(data);
    break;

#ifdef INTERBASE6_OR_LATER
  case blr_sql_date:
    result = conv_out_date(data);
    break;

  case blr_sql_time:
    result = conv_out_time(data);
    break;
#endif /* INTERBASE6_OR_LATER */

  case blr_quad:
    /* ISC_QUAD structure; since the DB engine doesn't support arrays of
    ** arrays, assume that this item refers to a blob id. */
  case blr_blob:
  case blr_blob_id:
    result = conv_out_blob( (ISC_QUAD *)data,
        status_vector, db_handle, trans_handle
      );
    break;

  default:
    raise_exception( NotSupportedError,
        "Outgoing conversion of array element of this type not supported "
        KIDB_REPORT " " KIDB_HOME_PAGE
      );
    return NULL;
  }

  assert (converter != NULL); /* Can't be NULL; may be None. */
  /* Obviously mustn't invoke the converter if the original value was not
  ** loaded properly from the database. */
  if (result != NULL) {
    /* Replacing the PyObject pointer in result is not a refcount leak; see the
    ** comments in dynamically_type_convert_output_obj_if_necessary. */
    result = dynamically_type_convert_output_obj_if_necessary(
        result, converter, data_type, data_subtype
      );
  }

  return result;
} /* conv_out_array_element */

/******************** OUTPUT FUNCTIONS:END ********************/


/******************** UTILITY FUNCTIONS:BEGIN ********************/

#define POPULATE_ARRAY_DESC_MEMORY_ERROR_IF_NULL(pointer) \
  if (pointer == NULL) { \
    PyErr_NoMemory(); \
    goto POPULATE_ARRAY_DESC_ERROR; \
  }


ISC_ARRAY_DESC *_populate_array_descriptor(
    /* These strings aren't null-terminated: */
    char *sqlvar_table_name, short sqlvar_table_name_length,
    char *sqlvar_field_name, short sqlvar_field_name_length,

    /* Boilerplate params: */
    ISC_STATUS *status_vector, isc_db_handle db_handle, isc_tr_handle trans_handle
  )
{
  ISC_ARRAY_DESC *desc;

  /* isc_array_lookup_* functions require null-terminated strings, but the
  ** relevant strings from the XSQLVAR structure are not null-terminated. */
  char *null_terminated_table_name = NULL, *null_terminated_field_name = NULL;

  /* Begin initial memory allocation section. */
  desc = kimem_main_malloc(sizeof(ISC_ARRAY_DESC));
  POPULATE_ARRAY_DESC_MEMORY_ERROR_IF_NULL(desc);

  null_terminated_table_name = kimem_main_malloc(sqlvar_table_name_length + 1);
  POPULATE_ARRAY_DESC_MEMORY_ERROR_IF_NULL(null_terminated_table_name);

  null_terminated_field_name = kimem_main_malloc(sqlvar_field_name_length + 1);
  POPULATE_ARRAY_DESC_MEMORY_ERROR_IF_NULL(null_terminated_field_name);
  /* End initial memory allocation section. */

  /* Copy the non-null-terminated strings table_name and field_name into
  ** null-terminated the strings null_terminated_*_name. */
  memcpy(null_terminated_table_name, sqlvar_table_name, sqlvar_table_name_length);
  null_terminated_table_name[sqlvar_table_name_length] = '\0';
  memcpy(null_terminated_field_name, sqlvar_field_name, sqlvar_field_name_length);
  null_terminated_field_name[sqlvar_field_name_length] = '\0';

  ENTER_DB
  isc_array_lookup_bounds(status_vector,
      &db_handle,
      &trans_handle,
      null_terminated_table_name,
      null_terminated_field_name,
      desc
    );
  LEAVE_DB
  if (DB_API_ERROR(status_vector)) {
    raise_sql_exception( OperationalError, "Array input conversion: ",
        status_vector
      );
    goto POPULATE_ARRAY_DESC_ERROR;
  }

  /* Successfully completed. */
  goto POPULATE_ARRAY_DESC_CLEANUP;

POPULATE_ARRAY_DESC_ERROR:
  if (desc != NULL) kimem_main_free(desc);
  desc = NULL;
  /* Fall through to generic cleanup. */

POPULATE_ARRAY_DESC_CLEANUP:
  if (null_terminated_table_name != NULL) kimem_main_free(null_terminated_table_name);
  if (null_terminated_field_name != NULL) kimem_main_free(null_terminated_field_name);

  return desc;
} /* _populate_array_descriptor */


/*****************************************************************************/

short *_extract_dimensions_sizes(
    ISC_ARRAY_DESC *desc,
    /* output param: */
    int *total_number_of_elements
  )
{
  short *dimensions;
  int dimension;
  unsigned short number_of_dimensions = desc->array_desc_dimensions;
  ISC_ARRAY_BOUND bounds_of_current_dimension;

  /* Populate the short-array named dimensions, and calculate the total number
  ** of elements: */
  dimensions = kimem_main_malloc((number_of_dimensions + 1) * sizeof(short));
  if (dimensions == NULL) {
    PyErr_NoMemory();
    return NULL;
  }

  *total_number_of_elements = 1;
  for (dimension = 0; dimension < number_of_dimensions; dimension++) {
    bounds_of_current_dimension = desc->array_desc_bounds[dimension];
    dimensions[dimension] =
          (bounds_of_current_dimension.array_bound_upper + 1)
         - bounds_of_current_dimension.array_bound_lower
      ;

    *total_number_of_elements *= dimensions[dimension];
  }

  /* The final element is set to a flag value (for pointer-walking convenience). */
  dimensions[number_of_dimensions] = DIMENSION_SIZE_END_MARKER;

  return dimensions;
} /* _extract_dimensions_sizes */


short _determine_sqlsubtype_for_array(
    ISC_STATUS *status_vector, isc_db_handle db_handle, isc_tr_handle trans_handle,
    char *table_name, short table_name_length, char *field_name, short field_name_length
  )
{
  /* Returns the subtype on success, or SQLSUBTYPE_DETERMINATION_ERROR on error. */
  const char *subtype_determination_statement =
       "SELECT FIELD_SPEC.RDB$FIELD_SUB_TYPE"
      " FROM RDB$FIELDS FIELD_SPEC, RDB$RELATION_FIELDS REL_FIELDS"
      " WHERE"
            " FIELD_SPEC.RDB$FIELD_NAME = REL_FIELDS.RDB$FIELD_SOURCE"
        " AND REL_FIELDS.RDB$RELATION_NAME = ?"
        " AND REL_FIELDS.RDB$FIELD_NAME = ?"
    ;
  XSQLDA *out_da = NULL;
  XSQLDA *in_da = NULL;
  XSQLVAR *in_var = NULL;
  XSQLVAR *out_var = NULL;
  isc_stmt_handle stmt_handle_sqlsubtype = NULL;

  short sqlsubtype = SQLSUBTYPE_DETERMINATION_ERROR;

  /* 2003.03.31: */
  in_da = kimem_xsqlda_malloc(XSQLDA_LENGTH(2));

  in_da->version = SQLDA_VERSION1;
  in_da->sqln = 2;
  in_da->sqld = 2;

  in_da->sqlvar      ->sqltype = SQL_TEXT;
  (in_da->sqlvar + 1)->sqltype = SQL_TEXT;

  /* Set the names of the relation.field for which we're determining precision. */
  in_var = in_da->sqlvar; /* First input variable. */
  in_var->sqllen = table_name_length;
  in_var->sqldata = table_name;

  in_var++; /* Second input variable. */
  in_var->sqllen = field_name_length;
  in_var->sqldata = field_name;

  /* Set up the output structures.  We know at design time exactly how they
  ** should be configured; there's no convoluted dance of dynamism here, as
  ** there is in servicing a generic Python-level query. */
  /* 2003.03.31: */
  out_da = (XSQLDA *) kimem_xsqlda_malloc(XSQLDA_LENGTH(1));

  out_da->version = SQLDA_VERSION1;
  out_da->sqln = 1;

  out_var = out_da->sqlvar;
  out_var->sqldata = (char *) kimem_main_malloc(sizeof(short));
  /* We won't actually use the null status of the output field (it will never
  ** be NULL), but the API requires that space be allocated anyway. */
  out_var->sqlind = (short *) kimem_main_malloc(sizeof(short));

  ENTER_DB
  isc_dsql_allocate_statement( status_vector, &db_handle, &stmt_handle_sqlsubtype );
  LEAVE_DB
  if (DB_API_ERROR(status_vector)) goto _DETERMINE_SQLSUBTYPE_FOR_ARRAY_CLEANUP;

  ENTER_DB
  isc_dsql_prepare( status_vector,
      &trans_handle,
      &stmt_handle_sqlsubtype,
      0, (char *) subtype_determination_statement, 3,
      out_da
    );
  LEAVE_DB
  if (DB_API_ERROR(status_vector)) goto _DETERMINE_SQLSUBTYPE_FOR_ARRAY_CLEANUP;

  ENTER_DB
  isc_dsql_execute2(
      status_vector, &trans_handle, &stmt_handle_sqlsubtype, 3, in_da, out_da
    );
  LEAVE_DB
  if (DB_API_ERROR(status_vector)) goto _DETERMINE_SQLSUBTYPE_FOR_ARRAY_CLEANUP;

  sqlsubtype = *((short *) out_var->sqldata);
_DETERMINE_SQLSUBTYPE_FOR_ARRAY_CLEANUP:
  if (stmt_handle_sqlsubtype != NULL) {
    /* 2003.10.06:
    ** The isc_dsql_free_statement call here is relatively safe because under
    ** normal circumstances the connection won't be severed between the time
    ** the statement handle is allocated with isc_dsql_allocate_statement
    ** (earlier in this same function) and the time it's freed (here). */
    ENTER_DB
    isc_dsql_free_statement( status_vector, &stmt_handle_sqlsubtype, DSQL_drop );
    LEAVE_DB
  }
  if (out_da != NULL) {
    kimem_main_free(out_da->sqlvar->sqldata);
    kimem_main_free(out_da->sqlvar->sqlind);
  }

  /* 2003.03.31: */
  kimem_xsqlda_free(out_da);
  kimem_xsqlda_free(in_da);

  if (DB_API_ERROR(status_vector)) {
    raise_sql_exception(InternalError,
        "_determine_sqlsubtype_for_array: ", status_vector
      );
    return SQLSUBTYPE_DETERMINATION_ERROR;
  } else {
    return sqlsubtype;
  }
} /* _determine_sqlsubtype_for_array */


/******************** UTILITY FUNCTIONS:END ********************/


/******************** DEBUGGING FUNCTIONS:BEGIN ********************/

#ifdef KIDB_DEBUGGERING
void dump_array_descriptor(ISC_ARRAY_DESC *desc) {
  int i;

  printf("\n--- DUMP OF ARRAY DESCRIPTOR:BEGIN ---\n");
  printf("array_desc_dtype: %d\n", desc->array_desc_dtype);
  printf("array_desc_scale: %d\n", desc->array_desc_scale);
  printf("array_desc_length: %d\n", desc->array_desc_length);
  printf("array_desc_relation_name: %s\n", desc->array_desc_relation_name);
  printf("array_desc_field_name: %s\n", desc->array_desc_field_name);
  printf("array_desc_dimensions: %d\n", desc->array_desc_dimensions);
  printf("array_desc_flags: %d\n", desc->array_desc_flags);

  printf("  -- BOUNDS:BEGIN --\n");
  for (i = 0; i < desc->array_desc_dimensions; i++) {
    ISC_ARRAY_BOUND bounds = (desc->array_desc_bounds)[i];
    printf("    bounds set #%2d: lower: %d ; upper: %d\n",
        i, bounds.array_bound_lower, bounds.array_bound_upper
      );
  }
  printf("  -- BOUNDS:END --\n");

  printf("--- DUMP OF ARRAY DESCRIPTOR:END ---\n\n");
}
#endif /* KIDB_DEBUGGERING */

/******************** DEBUGGING FUNCTIONS:END ********************/