sqlite3 how to get column index by column name

sqlite3GetColumnIndexByName.c

#include <stdlib.h>
#include "../sqlite3/sqlite3.h"
#include "domain.h"

/* okay this function is stolen; the rest are MINE */
unsigned long
djb2Hash(unsigned char *str)
{
    unsigned long hash = 5381;
    int c;

    while (c = *str++)
        hash = ((hash << 5) + hash) + c; /* hash * 33 + c */

    return hash;
}

const char **getColumnNames(sqlite3_stmt *stmt) {
  /*
   * Caller must free() the return value
   */
  int columnCount = sqlite3_column_count(stmt);
  const char **ret = malloc(sizeof(const char *) * columnCount + 1);
  //const char **iter = ret;
  int i = 0;
  for(; i < columnCount; i++) {
    //*(iter++) = sqlite3_column_name(stmt, i);
    ret[i] = sqlite3_column_name(stmt, i);
  }
  //iter = NULL;
  ret[i] = NULL;
  return ret;
}

unsigned long *hashStringArray(const char **arr) {
  /*
   * Returns a new array of integer hash values
   *
   * Caller must free return value
   */

  //Find length of arr
  int len = 0;
  for(const char **it = arr; it != NULL; it++) {
    ++len;
  }

  //Make the hashes
  unsigned long *ret = malloc(sizeof(unsigned long) * len + 1);
  int k = 0;
  for(const char **it = arr; it != NULL; it++) {
    ret[k++] = djb2Hash((unsigned char *) *it);
  }
  ret[k] = 0;

  return ret;
}

unsigned long *getHashedColumnNames(sqlite3_stmt *stmt) {
  /*
   * Caller must free return value
   */
  const char **columnNames = getColumnNames(stmt);
  unsigned long *ret = hashStringArray(columnNames);
  free(columnNames);
  return ret;
}

int getColumnIndexByName(sqlite3_stmt *stmt, const char *columnName) {
  /*
   * High level function to get the integer
   * column index from a string that's the
   * column name
   */

  unsigned long *const hashedColumnNames = getHashedColumnNames(stmt);

  unsigned long hashedColumnName = djb2Hash((unsigned char *) columnName);

  int columnIndex = 0;
  for(unsigned long *it = hashedColumnNames;
      *it; it++, columnIndex++) {
    if(*it == hashedColumnName) {
      free(hashedColumnNames);
      return columnIndex;
    }
  }

  free(hashedColumnNames);
  return -1; //failure
}