Php close session file

# Sessions

(opens new window) to the session_start function.

 if (version_compare(PHP_VERSION, '7.0.0') >= 0)  // php >= 7 version session_start([ 'cache_limiter' => 'private', 'read_and_close' => true, ]); > else  // php < 7 versionsession_start(); > ?> 

This feature also introduces a new php.ini setting named session.lazy_write , which defaults to true and means that session data is only rewritten, if it changes.

# Session Locking

As we all are aware that PHP writes session data into a file at server side. When a request is made to php script which starts the session via session_start() , PHP locks this session file resulting to block/wait other incoming requests for same session_id to complete, because of which the other requests will get stuck on session_start() until or unless the session file locked is not released

The session file remains locked until the script is completed or session is manually closed. To avoid this situation i.e. to prevent multiple requests getting blocked, we can start the session and close the session which will release the lock from session file and allow to continue the remaining requests.

// php < 7.0 // start session session_start(); // write data to session $_SESSION['id'] = 123; // session file is locked, so other requests are blocked // close the session, release lock session_write_close(); 

Now one will think if session is closed how we will read the session values, beautify even after session is closed, session is still available. So, we can still read the session data.

echo $_SESSION['id']; // will output 123 

In php >= 7.0, we can have read_only session, read_write session and lazy_write session, so it may not required to use session_write_close()

# Manipulating session data

The $_SESSION variable is an array, and you can retrieve or manipulate it like a normal array.

 // Starting the session session_start(); // Storing the value in session $_SESSION['id'] = 342; // conditional usage of session values that may have been set in a previous session if(!isset($_SESSION["login"]))  echo "Please login first"; exit; > // now you can use the login safely $user = $_SESSION["login"]; // Getting a value from the session data, or with default value, // using the Null Coalescing operator in PHP 7 $name = $_SESSION['name'] ?? 'Anonymous'; 

(opens new window) for more reference how to work on an array.

Note that if you store an object in a session, it can be retrieved gracefully only if you have an class autoloader or you have loaded the class already. Otherwise, the object will come out as the type __PHP_Incomplete_Class , which may later lead to crashes

# Warning:

(opens new window) So it can be strongly recommended to never store any personal information in $_SESSION . This would most critically include credit card numbers, government issued ids, and passwords; but would also extend into less assuming data like names, emails, phone numbers, etc which would allow a hacker to impersonate/compromise a legitimate user. As a general rule, use worthless/non-personal values, such as numerical identifiers, in session data.

# Destroy an entire session

If you’ve got a session which you wish to destroy, you can do this with session_destroy()

/* Let us assume that our session looks like this: Array([firstname] => Jon, [id] => 123) We first need to start our session: */ session_start(); /* We can now remove all the values from the `SESSION` superglobal: If you omitted this step all of the global variables stored in the superglobal would still exist even though the session had been destroyed. */ $_SESSION = array(); // If it's desired to kill the session, also delete the session cookie. // Note: This will destroy the session, and not just the session data! if (ini_get("session.use_cookies"))  $params = session_get_cookie_params(); setcookie(session_name(), '', time() - 42000, $params["path"], $params["domain"], $params["secure"], $params["httponly"] ); > //Finally we can destroy the session: session_destroy(); 

Using session_destroy() is different to using something like $_SESSION = array(); which will remove all of the values stored in the SESSION superglobal but it will not destroy the actual stored version of the session.

Note: We use $_SESSION = array(); instead of session_unset() because the manual

Only use session_unset() for older deprecated code that does not use $_SESSION.

# Session name

# Checking if session cookies have been created

Session name is the name of the cookie used to store sessions. You can use this to detect if cookies for a session have been created for the user:

if(isset($_COOKIE[session_name()]))  session_start(); > 

Note that this method is generally not useful unless you really don’t want to create cookies unnecessarily.

# Changing session name

You can update the session name by calling session_name() .

//Set the session name session_name('newname'); //Start the session session_start(); 

If no argument is provided into session_name() then the current session name is returned.

It should contain only alphanumeric characters; it should be short and descriptive (i.e. for users with enabled cookie warnings). The session name can’t consist of digits only, at least one letter must be present. Otherwise a new session id is generated every time.

# Safe Session Start With no Errors

Many developers have this problem when they work on huge projects, especially if they work on some modular CMS on plugins, addons, components etc. Here is solution for safe session start where if first checked PHP version to cover all versions and on next is checked if session is started. If session not exists then I start session safe. If session exists nothing happen.

if (version_compare(PHP_VERSION, '7.0.0') >= 0)  if(session_status() == PHP_SESSION_NONE)  session_start(array( 'cache_limiter' => 'private', 'read_and_close' => true, )); > > else if (version_compare(PHP_VERSION, '5.4.0') >= 0)  if (session_status() == PHP_SESSION_NONE)  session_start(); > > else  if(session_id() == '')  session_start(); > > 

This can help you a lot to avoid session_start error.

# Syntax

• void session_abort ( void )
• int session_cache_expire ([ string $new_cache_expire ] )
• void session_commit ( void )
• string session_create_id ([ string $prefix ] )
• bool session_decode ( string $data )
• bool session_destroy ( void )
• string session_encode ( void )
• int session_gc ( void )
• array session_get_cookie_params ( void )
• string session_id ([ string $id ] )
• bool session_is_registered ( string $name )
• string session_module_name ([ string $module ] )
• string session_name ([ string $name ] )
• bool session_regenerate_id ([ bool $delete_old_session = false ] )
• void session_register_shutdown ( void )
• bool session_register ( mixed $name [, mixed $. ] )
• void session_reset ( void )
• string session_save_path ([ string $path ] )
• void session_set_cookie_params ( int $lifetime [, string $path [, string $domain [, bool $secure = false [, bool $httponly = false ]]]] )
• bool session_set_save_handler ( callable $open , callable $close , callable $read , callable $write , callable $destroy , callable $gc [, callable $create_sid [, callable $validate_sid [, callable $update_timestamp ]]] )
• bool session_start ([ array $options = [] ] )
• int session_status ( void )
• bool session_unregister ( string $name )
• void session_unset ( void )
• void session_write_close ( void )

# Remarks

Note that calling session_start() even if the session has already started will result in a PHP warning.

Источник

session_destroy

session_destroy() destroys all of the data associated with the current session. It does not unset any of the global variables associated with the session, or unset the session cookie. To use the session variables again, session_start() has to be called.

Note: You do not have to call session_destroy() from usual code. Cleanup $_SESSION array rather than destroying session data.

In order to kill the session altogether, the session ID must also be unset. If a cookie is used to propagate the session ID (default behavior), then the session cookie must be deleted. setcookie() may be used for that.

When session.use_strict_mode is enabled. You do not have to remove obsolete session ID cookie because session module will not accept session ID cookie when there is no data associated to the session ID and set new session ID cookie. Enabling session.use_strict_mode is recommended for all sites.

Immediate session deletion may cause unwanted results. When there is concurrent requests, other connections may see sudden session data loss. e.g. Requests from JavaScript and/or requests from URL links.

Although current session module does not accept empty session ID cookie, but immediate session deletion may result in empty session ID cookie due to client(browser) side race condition. This will result that the client creates many session ID needlessly.

To avoid these, you must set deletion time-stamp to $_SESSION and reject access while later. Or make sure your application does not have concurrent requests. This applies to session_regenerate_id() also.

Parameters

This function has no parameters.

Источник

session_abort

session_abort() завершает сессию без сохранения данных. Таким образом, сохраняются исходные значения сессии.

Список параметров

У этой функции нет параметров.

Возвращаемые значения

Возвращает true в случае успешного выполнения или false в случае возникновения ошибки.

Список изменений

Смотрите также

• $_SESSION
• Директива конфигурации session.auto_start
• session_start() — Стартует новую сессию, либо возобновляет существующую
• session_reset() — Реинициализирует сессию оригинальными значениями
• session_commit() — Псевдоним session_write_close

User Contributed Notes 4 notes

To better understand this function you should execute this code first :

// First of all choose your path , For e.g. C:/session
session_save_path ( ‘Your Path here !’ );

// Define a Session Variable
$_SESSION [ ‘Key’ ] = ‘value’ ;

Var_dump ( session_status () == PHP_SESSION_ACTIVE );

// Output : bool(True) , it means you have an open session !
?>

Then you should execute this code :

// Choose the path that you used it in first part
session_save_path ( ‘Your path here’ );

// If you want to close session and keep your original data in your path , you should use session_abort()
session_abort ();

var_dump ( session_status ()== PHP_SESSION_ACTIVE );

// Output : bool(False) , it means your session closed .
?>

So if you have an open session , session_abort() will simply close it without effecting the external session data , so you can reload your data again from your path that you chose .

sess_o22iabs75j93uhc7i4jf1lecjk (file name)
city|s:6:»Sydney»; (content)

if we go to 2.php containing this code :

session_start ();
$_SESSION [ ‘country’ ]= «Australia» ;
echo session_encode ();
session_abort ();
session_start ();
echo «
» . session_encode ();
?>

when session_abort is executed , the session is closed and the change which here is the ‘country’ element of Session array is discarded .

demo1
session_start ();
if(!isset( $_SESSION [ ‘count’ ])) $_SESSION [ ‘count’ ] = 1 ;
>else $_SESSION [ ‘count’ ]++;
>
echo $_SESSION [ ‘count’ ];
//above, $_SESSION[‘count’] will keep increase;
?>

demo2
session_start ();
if(!isset( $_SESSION [ ‘count’ ])) $_SESSION [ ‘count’ ] = 1 ;
>else $_SESSION [ ‘count’ ]++;
>
session_abort ();
echo $_SESSION [ ‘count’ ];
//$_SESSION[‘count’] will always be 1;
?>

session_start ();
if(!isset( $_SESSION [ ‘count’ ])) $_SESSION [ ‘count’ ] = 1 ;
>else $_SESSION [ ‘count’ ]++;
session_abort ();
>
echo $_SESSION [ ‘count’ ];
//$_SESSION[‘count’] will always be 1;
//This will always echo 1 not the above code.
?>

• Функции для работы с сессиями
  • session_​abort
  • session_​cache_​expire
  • session_​cache_​limiter
  • session_​commit
  • session_​create_​id
  • session_​decode
  • session_​destroy
  • session_​encode
  • session_​gc
  • session_​get_​cookie_​params
  • session_​id
  • session_​module_​name
  • session_​name
  • session_​regenerate_​id
  • session_​register_​shutdown
  • session_​reset
  • session_​save_​path
  • session_​set_​cookie_​params
  • session_​set_​save_​handler
  • session_​start
  • session_​status
  • session_​unset
  • session_​write_​close

  Источник

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