mirror of
https://github.com/fsr/eseeva
synced 2024-11-15 08:53:11 +01:00
254 lines
7.4 KiB
PHP
Executable file
254 lines
7.4 KiB
PHP
Executable file
<?php
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//============================================================================
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// Name : keyLib.php
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// Author : Patrick Reipschläger, Lucas Woltmann
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// Version : 2.0
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// Date : 01-2017
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// Description : Provides several functions for creating and handling keys
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// for the ESE evaluation for students and tutors.
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//============================================================================
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// Constant for the file which contains the keys, should be used by all other scripts so it can easily be changed
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define ("KEYFILE", "db/eseeva.db");
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// Constants for the different key states that are possible, should always be used when altering or checking the state of a key
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define ("KEYSTATE_NONEXISTENT", "nonexistent");
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define ("KEYSTATE_UNISSUED", "unissued");
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define ("KEYSTATE_ISSUED", "issued");
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define ("KEYSTATE_ACTIVATED", "activated");
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define ("KEYSTATE_USED", "used");
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/**
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* Generates a key from the specified hash value.
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*
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* @return string
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*/
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function GenerateKey()
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{
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// create a hash using a unique id based on the servers system time and the sha1 hashing algorithm
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$hash = strtoupper(hash("sha1", uniqid()));
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// extract the desired number of digits out of the hash to generate the key
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return substr($hash, 0, 4) . "-" . substr($hash, 4, 4) . "-" . substr($hash, 8, 4) . "-" . substr($hash, 12, 4);
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//return substr($hash, 0, 2) . "-" . substr($hash, 2, 2) . "-" . substr($hash, 4, 2) . "-" . substr($hash, 6, 2);
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}
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/**
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* Generates the specified amount of keys. Be aware that this function just
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* creates an array of keys with no state assigned.
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*
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* @param integer $amount The amount of keys that should be generated
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* @return array
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*/
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function GenerateKeys($amount)
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{
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$keys = array();
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for ($i = 0; $i < $amount; $i++)
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{
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array_push($keys, GenerateKey());
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usleep(1);
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}
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return array_unique($keys);
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}
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/**
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* Generates a new keys in the database.
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* Returns true if the key file was created successfully, otherwise false.
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*
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* @param integer $keyAmount The amount of keys that should be generated.
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* @param string $fileName The name of the key database that should be created.
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*/
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function CreateKeys($keyAmount, $fileName)
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{
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$handle = new SQLite3($fileName);
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if (!$handle)
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return false;
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$handle->exec("DROP TABLE answers;");
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$handle->exec("CREATE TABLE IF NOT EXISTS 'answers'(KeyId text primary key,Status text,Student int,Answer);");
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$keys = GenerateKeys($keyAmount);
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$count = count($keys);
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for ($i = 0; $i < $count; $i++)
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{
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$stmt = $handle->prepare("INSERT INTO answers (KeyId, Status) VALUES (:key,:status);");
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if ($stmt)
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{
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$stmt->bindValue(':key', $keys[$i], SQLITE3_TEXT);
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$stmt->bindValue(':status', KEYSTATE_UNISSUED, SQLITE3_TEXT);
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$result = $stmt->execute();
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}
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else
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{
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$handle->close();
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return false;
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}
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}
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$handle->close();
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return true;
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}
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function AppendKeys($keyAmount, $fileName)
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{
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$handle = new SQLite3($fileName, SQLITE3_OPEN_READWRITE);
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if (!$handle)
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return false;
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$keys = GenerateKeys($keyAmount);
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$count = count($keys);
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for ($i = 0; $i < $count; $i++)
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{
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$stmt = $handle->prepare("INSERT INTO answers (KeyId, Status) VALUES (:key,:status);");
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if ($stmt)
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{
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$stmt->bindValue(':key', $keys[$i], SQLITE3_TEXT);
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$stmt->bindValue(':status', KEYSTATE_UNISSUED, SQLITE3_TEXT);
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$result = $stmt->execute();
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}
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else
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{
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$handle->close();
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return false;
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}
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}
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$handle->close();
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return true;
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}
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/**
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* Opens the database with the specified name and reads all key data that the database contains.
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* The resulting data type will be an array of arrays consisting of the key and its state.
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* Returns null if the key file could not be found or read.
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*
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* @param string $fileName The database which should be read.
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* @return array
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*/
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function ReadKeys($fileName)
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{
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if (!file_exists($fileName))
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return null;
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$handle = new SQLite3($fileName, SQLITE3_OPEN_READONLY);
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if (!$handle)
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return null;
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$data = $handle->query("SELECT KeyId, Status FROM answers;");
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$data = PrepareResult($data);
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$handle->close();
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if ($data)
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{
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return $data;
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}
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return array();
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}
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/**
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* Get the current state of the specified key from the database, which will be one of the defines
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* KEYSTATE constants.
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*
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* @param array $fileName The database with the keys.
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* @param string $key The key which state should be got. Passed by reference.
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* @return integer
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*/
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function GetKeyState($fileName, &$key)
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{
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if (!file_exists($fileName))
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return null;
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$handle = new SQLite3($fileName, SQLITE3_OPEN_READONLY);
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if (!$handle)
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return null;
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$stmt = $handle->prepare("SELECT Status FROM answers WHERE KeyId=:keyid;");
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if ($stmt)
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{
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$stmt->bindValue(':keyid', $key, SQLITE3_TEXT);
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$result = $stmt->execute();
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$result = $result->fetchArray(SQLITE3_ASSOC);
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$handle->close();
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return $result["Status"];
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}
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$handle->close();
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return KEYSTATE_NONEXISTENT;
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}
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/**
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* Set the state of the specified key to the specified state.
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* Returns true if the key was found within the key data and the state has been changed, otherwise false.
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*
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* @param array $fileName The database in which the key should be found.
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* @param string $key The key which state should be changed.
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* @param integer $newState The new state of the specified key. Must be on of the KEYSTATE constants.
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* @return boolean
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*/
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function SetKeyState($fileName, &$key, $newState)
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{
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if (!file_exists($fileName))
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return false;
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$handle = new SQLite3($fileName, SQLITE3_OPEN_READWRITE);
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if (!$handle)
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return false;
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//secure override by checking if key has been uesed already
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$stmt = $handle->prepare("UPDATE answers SET Status=:status WHERE KeyId=:keyid AND Status!=:status;");
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if ($stmt)
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{
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$stmt->bindValue(':keyid', $key, SQLITE3_TEXT);
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$stmt->bindValue(':status', $newState, SQLITE3_TEXT);
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$result = $stmt->execute();
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$handle->close();
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return true;
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}
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$handle->close();
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return false;
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}
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/**
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* Deletes a single key in the database if it has not been used yet.
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* Returns true if the key was deleted, otherwise false.
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*
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* @param array $fileName The database in which the key should be found.
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* @param string $key The key which should be deleted.
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* @return boolean
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*/
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function DeleteKey($fileName, &$key)
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{
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if (!file_exists($fileName))
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return false;
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$handle = new SQLite3($fileName, SQLITE3_OPEN_READWRITE);
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if (!$handle)
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return false;
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//secure deleting by checking if key has been uesed already
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$stmt = $handle->prepare("DELETE FROM answers WHERE KeyId=:keyid;");
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if ($stmt)
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{
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$stmt->bindValue(':keyid', $key, SQLITE3_TEXT);
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$result = $stmt->execute();
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$handle->close();
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return true;
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}
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$handle->close();
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return false;
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}
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/**
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* Prepares the results from the database to an array of keys with their state.
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*
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* @param array $resultSet Cursor from the sqlite database. Passed by reference.
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* @return array
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*/
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function PrepareResult(&$resultSet)
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{
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$result = array();
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$i = 0;
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while($res = $resultSet->fetchArray(SQLITE3_ASSOC))
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{
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foreach ($res as $key => $value) {
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$result[$i][$key] = $value;
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}
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$i++;
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}
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return $result;
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}
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?>
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