item_geofunc_buffer.cc

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   it under the terms of the GNU General Public License, version 2.0,
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   You should have received a copy of the GNU General Public License
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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

/**
  @file
  @brief
  This file contains the implementation for the Item that implements
  ST_Buffer().
*/

#include <sys/types.h>

#include <algorithm>
#include <cctype>
#include <cstdlib>
#include <cstring>
#include <memory>  // std::unique_ptr
#include <vector>

#include <boost/concept/usage.hpp>
#include <boost/geometry/algorithms/buffer.hpp>
#include <boost/geometry/strategies/agnostic/buffer_distance_symmetric.hpp>
#include <boost/geometry/strategies/buffer.hpp>
#include <boost/geometry/strategies/cartesian/buffer_end_flat.hpp>
#include <boost/geometry/strategies/cartesian/buffer_end_round.hpp>
#include <boost/geometry/strategies/cartesian/buffer_join_miter.hpp>
#include <boost/geometry/strategies/cartesian/buffer_join_round.hpp>
#include <boost/geometry/strategies/cartesian/buffer_point_circle.hpp>
#include <boost/geometry/strategies/cartesian/buffer_point_square.hpp>
#include <boost/geometry/strategies/cartesian/buffer_side_straight.hpp>
#include <boost/geometry/strategies/strategies.hpp>
#include <boost/iterator/iterator_facade.hpp>

#include "m_string.h"
#include "my_byteorder.h"
#include "my_dbug.h"
#include "my_inttypes.h"
#include "my_sys.h"
#include "mysql/strings/m_ctype.h"
#include "mysqld_error.h"
#include "nulls.h"
#include "sql/current_thd.h"
#include "sql/dd/cache/dictionary_client.h"
#include "sql/dd/types/spatial_reference_system.h"
#include "sql/derror.h"  // ER_THD
#include "sql/item.h"
#include "sql/item_geofunc.h"
#include "sql/item_geofunc_internal.h"
#include "sql/item_strfunc.h"
#include "sql/parse_location.h"  // POS
#include "sql/spatial.h"
#include "sql/sql_class.h"  // THD
#include "sql/sql_error.h"
#include "sql/sql_exception_handler.h"
#include "sql/srs_fetcher.h"
#include "sql/system_variables.h"
#include "sql_string.h"
#include "template_utils.h"

class PT_item_list;

namespace boost {
namespace geometry {
namespace cs {
struct cartesian;
}  // namespace cs
}  // namespace geometry
}  // namespace boost

static const char *const buffer_strategy_names[] = {
    "invalid_strategy", "end_round",    "end_flat",    "join_round",
    "join_miter",       "point_circle", "point_square"};

template <typename Char_type>
inline int char_icmp(const Char_type a, const Char_type b) {
  const int a1 = std::tolower(a);
  const int b1 = std::tolower(b);
  return a1 > b1 ? 1 : (a1 < b1 ? -1 : 0);
}

/**
  Case insensitive comparison of two ascii strings.
  @param a '\0' ended string.
  @param b '\0' ended string.
 */
template <typename Char_type>
int str_icmp(const Char_type *a, const Char_type *b) {
  int ret = 0, i;

  for (i = 0; a[i] != 0 && b[i] != 0; i++)
    if ((ret = char_icmp(a[i], b[i]))) return ret;
  if (a[i] == 0 && b[i] != 0) return -1;
  if (a[i] != 0 && b[i] == 0) return 1;
  return 0;
}

Item_func_buffer_strategy::Item_func_buffer_strategy(const POS &pos,
                                                     PT_item_list *ilist)
    : Item_str_func(pos, ilist) {
  // Here we want to use the String::set(const char*, ..) version.
  const char *pbuf = tmp_buffer;
  tmp_value.set(pbuf, 0, nullptr);
}

bool Item_func_buffer_strategy::resolve_type(THD *thd) {
  if (param_type_is_default(thd, 0, 1)) return true;
  if (param_type_is_default(thd, 1, 2, MYSQL_TYPE_DOUBLE)) return true;
  set_data_type_string(16, &my_charset_bin);
  set_nullable(true);
  return false;
}

String *Item_func_buffer_strategy::val_str(String * /* str_arg */) {
  String str;
  String *strat_name = args[0]->val_str_ascii(&str);
  if ((null_value = args[0]->null_value)) {
    assert(is_nullable());
    return nullptr;
  }

  // Get the NULL-terminated ascii string.
  const char *pstrat_name = strat_name->c_ptr_safe();

  bool found = false;

  tmp_value.set_charset(&my_charset_bin);
  // The tmp_value is supposed to always stores a {uint32,double} pair,
  // and it uses a char tmp_buffer[16] array data member.
  uchar *result_buf = pointer_cast<uchar *>(tmp_value.ptr());

  // Although the result of this item node is never persisted, we still have to
  // use portable endianness access otherwise unaligned access will crash
  // on sparc CPUs.
  for (uint32 i = 0; i <= max_strategy; i++) {
    // The above var_str_ascii() call makes the strat_name an ascii string so
    // we can do below comparison.
    if (str_icmp(pstrat_name, buffer_strategy_names[i]) != 0) continue;

    int4store(result_buf, i);
    result_buf += 4;
    const enum_buffer_strategies istrat =
        static_cast<enum_buffer_strategies>(i);

    /*
      The end_flat and point_square strategies must have no more arguments;
      The rest strategies must have 2nd parameter which must be a positive
      numeric value, and we will store it as a double.
      We use float8store to ensure that the value is independent of endianness.
    */
    if (istrat != end_flat && istrat != point_square) {
      if (arg_count != 2) {
        my_error(ER_WRONG_ARGUMENTS, MYF(0), func_name());
        return error_str();
      }

      const double val = args[1]->val_real();
      if ((null_value = args[1]->null_value)) {
        assert(is_nullable());
        return nullptr;
      }
      if (val <= 0) {
        my_error(ER_WRONG_ARGUMENTS, MYF(0), func_name());
        return error_str();
      }

      if (istrat != join_miter &&
          val > current_thd->variables.max_points_in_geometry) {
        my_error(ER_GIS_MAX_POINTS_IN_GEOMETRY_OVERFLOWED, MYF(0),
                 "points_per_circle",
                 current_thd->variables.max_points_in_geometry, func_name());
        return error_str();
      }

      float8store(result_buf, val);
    } else if (arg_count != 1) {
      my_error(ER_WRONG_ARGUMENTS, MYF(0), func_name());
      return error_str();
    } else
      float8store(result_buf, 0.0);

    found = true;

    break;
  }

  // Unrecognized strategy names, report error.
  if (!found) {
    my_error(ER_WRONG_ARGUMENTS, MYF(0), func_name());
    return error_str();
  }
  tmp_value.length(12);

  return &tmp_value;
}