user_guide_src/source/general/compatibility_functions.rst - code-igniter-v3-giggi - Gitiles

 #######################
 Compatibility Functions
 #######################

 CodeIgniter provides a set of compatibility functions that enable
 you to use functions what are otherwise natively available in PHP,
 but only in higher versions or depending on a certain extension.

 Being custom implementations, these functions will also have some
 set of dependencies on their own, but are still useful if your
 PHP setup doesn't offer them natively.

 .. note:: Much like the :doc:`common functions <common_functions>`, the
 	compatibility functions are always available, as long as
 	their dependencies are met.

 .. contents::
   :local:

 .. raw:: html

   <div class="custom-index container"></div>

 ****************
 Password Hashing
 ****************

 This set of compatibility functions offers a "backport" of PHP's
 standard `Password Hashing extension <http://php.net/password>`_
 that is otherwise available only since PHP 5.5.

 Dependencies
 ============

 - PHP 5.3.7
 - ``CRYPT_BLOWFISH`` support for ``crypt()``

 Constants
 =========

 - ``PASSWORD_BCRYPT``
 - ``PASSWORD_DEFAULT``

 Function reference
 ==================

 .. php:function:: password_get_info($hash)

 	:param	string	$hash: Password hash
 	:returns:	Information about the hashed password
 	:rtype:	array

 	For more information, please refer to the `PHP manual for
 	password_get_info() <http://php.net/password_get_info>`_.

 .. php:function:: password_hash($password, $algo[, $options = array()])

 	:param	string	$password: Plain-text password
 	:param	int	$algo: Hashing algorithm
 	:param	array	$options: Hashing options
 	:returns:	Hashed password or FALSE on failure
 	:rtype:	string

 	For more information, please refer to the `PHP manual for
 	password_hash() <http://php.net/password_hash>`_.

 	.. note:: Unless you provide your own (and valid) salt, this function
 		has a further dependency on an available CSPRNG source. Each
 		of the following would satisfy that:
 		- ``mcrypt_create_iv()`` with ``MCRYPT_DEV_URANDOM``
 		- ``openssl_random_pseudo_bytes()``
 		- /dev/arandom
 		- /dev/urandom

 .. php:function:: password_needs_rehash()

 	:param	string	$hash: Password hash
 	:param	int	$algo: Hashing algorithm
 	:param	array	$options: Hashing options
 	:returns:	TRUE if the hash should be rehashed to match the given algorithm and options, FALSE otherwise
 	:rtype:	bool

 	For more information, please refer to the `PHP manual for
 	password_needs_rehash() <http://php.net/password_needs_rehash>`_.

 .. php:function:: password_verify($password, $hash)

 	:param	string	$password: Plain-text password
 	:param	string	$hash: Password hash
 	:returns:	TRUE if the password matches the hash, FALSE if not
 	:rtype:	bool

 	For more information, please refer to the `PHP manual for
 	password_verify() <http://php.net/password_verify>`_.

 *********************
 Hash (Message Digest)
 *********************

 This compatibility layer contains backports for the ``hash_equals()``
 and ``hash_pbkdf2()`` functions, which otherwise require PHP 5.6 and/or
 PHP 5.5 respectively.

 Dependencies
 ============

 - None

 Function reference
 ==================

 .. php:function:: hash_equals($known_string, $user_string)

 	:param	string	$known_string: Known string
 	:param	string	$user_string: User-supplied string
 	:returns:	TRUE if the strings match, FALSE otherwise
 	:rtype:	string

 	For more information, please refer to the `PHP manual for
 	hash_equals() <http://php.net/hash_equals>`_.

 .. php:function:: hash_pbkdf2($algo, $password, $salt, $iterations[, $length = 0[, $raw_output = FALSE]])

 	:param	string	$algo: Hashing algorithm
 	:param	string	$password: Password
 	:param	string	$salt: Hash salt
 	:param	int	$iterations: Number of iterations to perform during derivation
 	:param	int	$length: Output string length
 	:param	bool	$raw_output: Whether to return raw binary data
 	:returns:	Password-derived key or FALSE on failure
 	:rtype:	string

 	For more information, please refer to the `PHP manual for
 	hash_pbkdf2() <http://php.net/hash_pbkdf2>`_.

 ****************
 Multibyte String
 ****************

 This set of compatibility functions offers limited support for PHP's
 `Multibyte String extension <http://php.net/mbstring>`_. Because of
 the limited alternative solutions, only a few functions are available.

 .. note:: When a character set parameter is ommited,
 	``$config['charset']`` will be used.

 Dependencies
 ============

 - `iconv <http://php.net/iconv>`_ extension

 .. important:: This dependency is optional and these functions will
 	always be declared. If iconv is not available, they WILL
 	fall-back to their non-mbstring versions.

 .. important:: Where a character set is supplied, it must be
 	supported by iconv and in a format that it recognizes.

 .. note:: For you own dependency check on the actual mbstring
 	extension, use the ``MB_ENABLED`` constant.

 Function reference
 ==================

 .. php:function:: mb_strlen($str[, $encoding = NULL])

 	:param	string	$str: Input string
 	:param	string	$encoding: Character set
 	:returns:	Number of characters in the input string or FALSE on failure
 	:rtype:	string

 	For more information, please refer to the `PHP manual for
 	mb_strlen() <http://php.net/mb_strlen>`_.

 .. php:function:: mb_strpos($haystack, $needle[, $offset = 0[, $encoding = NULL]])

 	:param	string	$haystack: String to search in
 	:param	string	$needle: Part of string to search for
 	:param	int	$offset: Search offset
 	:param	string	$encoding: Character set
 	:returns:	Numeric character position of where $needle was found or FALSE if not found
 	:rtype:	mixed

 	For more information, please refer to the `PHP manual for
 	mb_strpos() <http://php.net/mb_strpos>`_.

 .. php:function:: mb_substr($str, $start[, $length = NULL[, $encoding = NULL]])

 	:param	string	$str: Input string
 	:param	int	$start: Position of first character
 	:param	int	$length: Maximum number of characters
 	:param	string	$encoding: Character set
 	:returns:	Portion of $str specified by $start and $length or FALSE on failure
 	:rtype:	string

 	For more information, please refer to the `PHP manual for
 	mb_substr() <http://php.net/mb_substr>`_.

 ******************
 Standard Functions
 ******************

 This set of compatibility functions offers support for a few
 standard functions in PHP that otherwise require a newer PHP version.

 Dependencies
 ============

 - None

 Function reference
 ==================

 .. php:function:: array_column(array $array, $column_key[, $index_key = NULL])

 	:param	array	$array: Array to fetch results from
 	:param	mixed	$column_key: Key of the column to return values from
 	:param	mixed	$index_key: Key to use for the returned values
 	:returns:	An array of values representing a single column from the input array
 	:rtype:	array

 	For more information, please refer to the `PHP manual for
 	array_column() <http://php.net/array_column>`_.

 .. php:function:: hex2bin($data)

 	:param	array	$data: Hexadecimal representation of data
 	:returns:	Binary representation of the given data
 	:rtype:	string

 	For more information, please refer to the `PHP manual for hex2bin()
 	<http://php.net/hex2bin>`_.
	#######################
	Compatibility Functions
	#######################

	CodeIgniter provides a set of compatibility functions that enable
	you to use functions what are otherwise natively available in PHP,
	but only in higher versions or depending on a certain extension.

	Being custom implementations, these functions will also have some
	set of dependencies on their own, but are still useful if your
	PHP setup doesn't offer them natively.

	.. note:: Much like the :doc:`common functions <common_functions>`, the
	compatibility functions are always available, as long as
	their dependencies are met.

	.. contents::
	:local:

	.. raw:: html

	<div class="custom-index container"></div>

	****************
	Password Hashing
	****************

	This set of compatibility functions offers a "backport" of PHP's
	standard `Password Hashing extension <http://php.net/password>`_
	that is otherwise available only since PHP 5.5.

	Dependencies
	============

	- PHP 5.3.7
	- ``CRYPT_BLOWFISH`` support for ``crypt()``

	Constants
	=========

	- ``PASSWORD_BCRYPT``
	- ``PASSWORD_DEFAULT``

	Function reference
	==================

	.. php:function:: password_get_info($hash)

	:param string $hash: Password hash
	:returns: Information about the hashed password
	:rtype: array

	For more information, please refer to the `PHP manual for
	password_get_info() <http://php.net/password_get_info>`_.

	.. php:function:: password_hash($password, $algo[, $options = array()])

	:param string $password: Plain-text password
	:param int $algo: Hashing algorithm
	:param array $options: Hashing options
	:returns: Hashed password or FALSE on failure
	:rtype: string

	For more information, please refer to the `PHP manual for
	password_hash() <http://php.net/password_hash>`_.

	.. note:: Unless you provide your own (and valid) salt, this function
	has a further dependency on an available CSPRNG source. Each
	of the following would satisfy that:
	- ``mcrypt_create_iv()`` with ``MCRYPT_DEV_URANDOM``
	- ``openssl_random_pseudo_bytes()``
	- /dev/arandom
	- /dev/urandom

	.. php:function:: password_needs_rehash()

	:param string $hash: Password hash
	:param int $algo: Hashing algorithm
	:param array $options: Hashing options
	:returns: TRUE if the hash should be rehashed to match the given algorithm and options, FALSE otherwise
	:rtype: bool

	For more information, please refer to the `PHP manual for
	password_needs_rehash() <http://php.net/password_needs_rehash>`_.

	.. php:function:: password_verify($password, $hash)

	:param string $password: Plain-text password
	:param string $hash: Password hash
	:returns: TRUE if the password matches the hash, FALSE if not
	:rtype: bool

	For more information, please refer to the `PHP manual for
	password_verify() <http://php.net/password_verify>`_.

	*********************
	Hash (Message Digest)
	*********************

	This compatibility layer contains backports for the ``hash_equals()``
	and ``hash_pbkdf2()`` functions, which otherwise require PHP 5.6 and/or
	PHP 5.5 respectively.

	Dependencies
	============

	- None

	Function reference
	==================

	.. php:function:: hash_equals($known_string, $user_string)

	:param string $known_string: Known string
	:param string $user_string: User-supplied string
	:returns: TRUE if the strings match, FALSE otherwise
	:rtype: string

	For more information, please refer to the `PHP manual for
	hash_equals() <http://php.net/hash_equals>`_.

	.. php:function:: hash_pbkdf2($algo, $password, $salt, $iterations[, $length = 0[, $raw_output = FALSE]])

	:param string $algo: Hashing algorithm
	:param string $password: Password
	:param string $salt: Hash salt
	:param int $iterations: Number of iterations to perform during derivation
	:param int $length: Output string length
	:param bool $raw_output: Whether to return raw binary data
	:returns: Password-derived key or FALSE on failure
	:rtype: string

	For more information, please refer to the `PHP manual for
	hash_pbkdf2() <http://php.net/hash_pbkdf2>`_.

	****************
	Multibyte String
	****************

	This set of compatibility functions offers limited support for PHP's
	`Multibyte String extension <http://php.net/mbstring>`_. Because of
	the limited alternative solutions, only a few functions are available.

	.. note:: When a character set parameter is ommited,
	``$config['charset']`` will be used.

	Dependencies
	============

	- `iconv <http://php.net/iconv>`_ extension

	.. important:: This dependency is optional and these functions will
	always be declared. If iconv is not available, they WILL
	fall-back to their non-mbstring versions.

	.. important:: Where a character set is supplied, it must be
	supported by iconv and in a format that it recognizes.

	.. note:: For you own dependency check on the actual mbstring
	extension, use the ``MB_ENABLED`` constant.

	Function reference
	==================

	.. php:function:: mb_strlen($str[, $encoding = NULL])

	:param string $str: Input string
	:param string $encoding: Character set
	:returns: Number of characters in the input string or FALSE on failure
	:rtype: string

	For more information, please refer to the `PHP manual for
	mb_strlen() <http://php.net/mb_strlen>`_.

	.. php:function:: mb_strpos($haystack, $needle[, $offset = 0[, $encoding = NULL]])

	:param string $haystack: String to search in
	:param string $needle: Part of string to search for
	:param int $offset: Search offset
	:param string $encoding: Character set
	:returns: Numeric character position of where $needle was found or FALSE if not found
	:rtype: mixed

	For more information, please refer to the `PHP manual for
	mb_strpos() <http://php.net/mb_strpos>`_.

	.. php:function:: mb_substr($str, $start[, $length = NULL[, $encoding = NULL]])

	:param string $str: Input string
	:param int $start: Position of first character
	:param int $length: Maximum number of characters
	:param string $encoding: Character set
	:returns: Portion of $str specified by $start and $length or FALSE on failure
	:rtype: string

	For more information, please refer to the `PHP manual for
	mb_substr() <http://php.net/mb_substr>`_.

	******************
	Standard Functions
	******************

	This set of compatibility functions offers support for a few
	standard functions in PHP that otherwise require a newer PHP version.

	Dependencies
	============

	- None

	Function reference
	==================

	.. php:function:: array_column(array $array, $column_key[, $index_key = NULL])

	:param array $array: Array to fetch results from
	:param mixed $column_key: Key of the column to return values from
	:param mixed $index_key: Key to use for the returned values
	:returns: An array of values representing a single column from the input array
	:rtype: array

	For more information, please refer to the `PHP manual for
	array_column() <http://php.net/array_column>`_.

	.. php:function:: hex2bin($data)

	:param array $data: Hexadecimal representation of data
	:returns: Binary representation of the given data
	:rtype: string

	For more information, please refer to the `PHP manual for hex2bin()
	<http://php.net/hex2bin>`_.