Podręcznik PHP
Poprzedni |  | Następny

# XXXIII. Identyfikacja błędów i kontrola pracy

# Wstęp

Funkcje opisane w tej części podręcznika dotyczą identyfikacji obsługi błędów oraz kontroli pracy (rejestrowania informacji o zdarzeniach). Pozwalają na definiowanie odautorskich zasad (mechanizmów) identyfikacji błędów oraz zachowań w razie ich wystąpienia.

Prace aplikacji można kontrolować przez zapisywanie informacji o ważniejszych wykonywanych czynnościach w pliku, dzienniku systemowym, wysyłając na konto pocztowe lub na przyklad wysyłając list elektroniczny do bramki SMS dostarczyć wiadomość na komórke.

Można w ten sposób dostosowywać poziom, znaczenie i reakcje w zależności od potrzeby sytuacji.

# Wymagania

Do zbudowania tego rozszerzenia nie są wymagane żadne zewnętrzne biblioteki.

# Instalacja

By używać tych funkcji, nie trzeba niczego instalować. Są one częścią jądra PHP.

# Konfiguracja uruchomieniowa

Na działanie tych funcji wpływają ustawienia zawarte w pliku `php.ini`.

Tabela 1. Errors and Logging Configuration Options

Name | Default | Changeable | Changelog
--- | --- | --- | ---
error_reporting | NULL | PHP_INI_ALL |
display_errors | "1" | PHP_INI_ALL |
display_startup_errors | "0" | PHP_INI_ALL | Available since PHP 4.0.3.
log_errors | "0" | PHP_INI_ALL |
log_errors_max_len | "1024" | PHP_INI_ALL | Available since PHP 4.3.0.
ignore_repeated_errors | "0" | PHP_INI_ALL | Available since PHP 4.3.0.
ignore_repeated_source | "0" | PHP_INI_ALL | Available since PHP 4.3.0.
report_memleaks | "1" | PHP_INI_ALL | Available since PHP 4.3.0.
track_errors | "0" | PHP_INI_ALL |
html_errors | "1" | PHP_INI_ALL | PHP_INI_SYSTEM in PHP <= 4.2.3. Available since PHP 4.0.2.
docref_root | "" | PHP_INI_ALL | Available since PHP 4.3.0.
docref_ext | "" | PHP_INI_ALL | Available since PHP 4.3.2.
error_prepend_string | NULL | PHP_INI_ALL |
error_append_string | NULL | PHP_INI_ALL |
error_log | NULL | PHP_INI_ALL |
warn_plus_overloading | NULL | PHP_INI?? |

Szczegóły i definicje dotyczące stałych PHP_INI_* znajdują się w rozdziale Dodatek G.

Oto krótkie wyjaśnienie dyrektyw konfiguracji.

`error_reporting` integer

  Set the error reporting level. The parameter is either an integer representing a bit field, or named constants. The error_reporting levels and constants are described in Predefined Constants, and in `php.ini`. To set at runtime, use the error_reporting() function. See also the display_errors directive.

  In PHP 4 and PHP 5 the default value is E_ALL & ~E_NOTICE. This setting does not show `E_NOTICE` level errors. You may want to show them during development.

  > Notatka: Enabling `E_NOTICE` during development has some benefits. For debugging purposes: NOTICE messages will warn you about possible bugs in your code. For example, use of unassigned values is warned. It is extremely useful to find typos and to save time for debugging. NOTICE messages will warn you about bad style. For example, $arr[item] is better to be written as $arr['item'] since PHP tries to treat "item" as constant. If it is not a constant, PHP assumes it is a string index for the array.

  > Notatka: In PHP 5 a new error level `E_STRICT` is available. As `E_STRICT` is not included within `E_ALL` you have to explicitly enable this kind of error level. Enabling `E_STRICT` during development has some benefits. STRICT messages will help you to use the latest and greatest suggested method of coding, for example warn you about using deprecated functions.

  In PHP 3, the default setting is `(E_ERROR | E_WARNING | E_PARSE)`, meaning the same thing. Note, however, that since constants are not supported in PHP 3's `php3.ini`, the error_reporting setting there must be numeric; hence, it is `7`.

`display_errors` boolean

  This determines whether errors should be printed to the screen as part of the output or if they should be hidden from the user.

  > Notatka: This is a feature to support your development and should never be used on production systems (e.g. systems connected to the internet).

  > Notatka: Although display_errors may be set at runtime (with ini_set()), it won't have any affect if the script has fatal errors. This is because the desired runtime action does not get executed.

`display_startup_errors` boolean

  Even when display_errors is on, errors that occur during PHP's startup sequence are not displayed. It's strongly recommended to keep display_startup_errors off, except for debugging.

`log_errors` boolean

  Tells whether script error messages should be logged to the server's error log or error_log. This option is thus server-specific.

  > Notatka: You're strongly advised to use error logging in place of error displaying on production web sites.

`log_errors_max_len` integer

  Set the maximum length of log_errors in bytes. In error_log information about the source is added. The default is 1024 and 0 allows to not apply any maximum length at all. This length is applied to logged errors, displayed errors and also to $php_errormsg.

  Jeśli użyty zostanie typ integer, wartość zostanie liczona w bajtach. Można także użyć notacji skrótowej opisanej w FAQ.

`ignore_repeated_errors` boolean

  Do not log repeated messages. Repeated errors must occur in the same file on the same line until ignore_repeated_source is set true.

`ignore_repeated_source` boolean

  Ignore source of message when ignoring repeated messages. When this setting is On you will not log errors with repeated messages from different files or sourcelines.

`report_memleaks` boolean

  If this parameter is set to Off, then memory leaks will not be shown (on stdout or in the log). This has only effect in a debug compile, and if error_reporting includes E_WARNING in the allowed list

`track_errors` boolean

  If enabled, the last error message will always be present in the variable $php_errormsg.

`html_errors` boolean

  Turn off HTML tags in error messages. The new format for HTML errors produces clickable messages that direct the user to a page describing the error or function in causing the error. These references are affected by docref_root and docref_ext.

`docref_root` string

  The new error format contains a reference to a page describing the error or function causing the error. In case of manual pages you can download the manual in your language and set this ini directive to the URL of your local copy. If your local copy of the manual can be reached by '/manual/' you can simply use `docref_root=/manual/`. Additional you have to set docref_ext to match the fileextensions of your copy `docref_ext=.html`. It is possible to use external references. For example you can use `docref_root=http://manual/en/` or `docref_root="http://landonize.it/?how=url&theme=classic&filter=Landon &url=http%3A%2F%2Fwww.php.net%2F"`

  Most of the time you want the docref_root value to end with a slash '/'. But see the second example above which does not have nor need it.

  > Notatka: This is a feature to support your development since it makes it easy to lookup a function description. However it should never be used on production systems (e.g. systems connected to the internet).

`docref_ext` string

  See docref_root.

  > Notatka: The value of docref_ext must begin with a dot '.'.

`error_prepend_string` string

  String to output before an error message.

`error_append_string` string

  String to output after an error message.

`error_log` string

  Name of the file where script errors should be logged. The file should be writable by the web server's user. If the special value `syslog` is used, the errors are sent to the system logger instead. On Unix, this means syslog(3) and on Windows NT it means the event log. The system logger is not supported on Windows 95. See also: syslog(). If this directive is not set, errors are sent to the SAPI error logger. For example, it is an error log in Apache or `stderr` in CLI.

`warn_plus_overloading` boolean

  If enabled, this option makes PHP output a warning when the plus (`+`) operator is used on strings. This is to make it easier to find scripts that need to be rewritten to using the string concatenator instead (`.`). This option doesn't exist as of PHP 4.

# Stałe predefiniowane

Poniższe stałe są częścią jądra PHP a więc są zawsze widoczne.

> Notatka: You may use these constant names in `php.ini` but not outside of PHP, like in `httpd.conf`, where you'd use the bitmask values instead.

Tabela 2. Errors and Logging

Value | Constant | Description | Note
--- | --- | --- | ---
1 | `E_ERROR` (integer) | Fatal run-time errors. These indicate errors that can not be recovered from, such as a memory allocation problem. Execution of the script is halted. |
2 | `E_WARNING` (integer) | Run-time warnings (non-fatal errors). Execution of the script is not halted. |
4 | `E_PARSE` (integer) | Compile-time parse errors. Parse errors should only be generated by the parser. |
8 | `E_NOTICE` (integer) | Run-time notices. Indicate that the script encountered something that could indicate an error, but could also happen in the normal course of running a script. |
16 | `E_CORE_ERROR` (integer) | Fatal errors that occur during PHP's initial startup. This is like an `E_ERROR`, except it is generated by the core of PHP. | since PHP 4
32 | `E_CORE_WARNING` (integer) | Warnings (non-fatal errors) that occur during PHP's initial startup. This is like an `E_WARNING`, except it is generated by the core of PHP. | since PHP 4
64 | `E_COMPILE_ERROR` (integer) | Fatal compile-time errors. This is like an `E_ERROR`, except it is generated by the Zend Scripting Engine. | since PHP 4
128 | `E_COMPILE_WARNING` (integer) | Compile-time warnings (non-fatal errors). This is like an `E_WARNING`, except it is generated by the Zend Scripting Engine. | since PHP 4
256 | `E_USER_ERROR` (integer) | User-generated error message. This is like an `E_ERROR`, except it is generated in PHP code by using the PHP function trigger_error(). | since PHP 4
512 | `E_USER_WARNING` (integer) | User-generated warning message. This is like an `E_WARNING`, except it is generated in PHP code by using the PHP function trigger_error(). | since PHP 4
1024 | `E_USER_NOTICE` (integer) | User-generated notice message. This is like an `E_NOTICE`, except it is generated in PHP code by using the PHP function trigger_error(). | since PHP 4
2048 | `E_STRICT` (integer) | Run-time notices. Enable to have PHP suggest changes to your code which will ensure the best interoperability and forward compatibility of your code. | since PHP 5
4096 | `E_RECOVERABLE_ERROR` (integer) | Catchable fatal error. It indicates that a probably dangerous error occured, but did not leave the Engine in an unstable state. If the error is not caught by a user defined handle (see also set_error_handler()), the application aborts as it was an `E_ERROR`. | since PHP 5.2.0
8191 | `E_ALL` (integer) | All errors and warnings, as supported, except of level `E_STRICT` in PHP < 6. | 6143 in PHP 5.2.x and 2047 previously

The above values (either numerical or symbolic) are used to build up a bitmask that specifies which errors to report. You can use the bitwise operators to combine these values or mask out certain types of errors. Note that only '|', '~', '!', '^' and '&' will be understood within `php.ini`, however, and that no bitwise operators will be understood within `php3.ini`.

# Przykłady

Below we can see an example of using the error handling capabilities in PHP. We define an error handling function which logs the information into a file (using an XML format), and e-mails the developer in case a critical error in the logic happens.

Przykład 1. Using error handling in a script

`<?php
// we will do our own error handling
error_reporting(0);
// user defined error handling function
function userErrorHandler($errno, $errmsg, $filename, $linenum, $vars)
{
// timestamp for the error entry
$dt = date("Y-m-d H:i:s (T)");
// define an assoc array of error string
// in reality the only entries we should
// consider are E_WARNING, E_NOTICE, E_USER_ERROR,
// E_USER_WARNING and E_USER_NOTICE
$errortype = array (
E_ERROR => 'Error',
E_WARNING => 'Warning',
E_PARSE => 'Parsing Error',
E_NOTICE => 'Notice',
E_CORE_ERROR => 'Core Error',
E_CORE_WARNING => 'Core Warning',
E_COMPILE_ERROR => 'Compile Error',
E_COMPILE_WARNING => 'Compile Warning',
E_USER_ERROR => 'User Error',
E_USER_WARNING => 'User Warning',
E_USER_NOTICE => 'User Notice',
E_STRICT => 'Runtime Notice',
E_RECOVERABLE_ERROR => 'Catchable Fatal Error'
);
// set of errors for which a var trace will be saved
$user_errors = array(E_USER_ERROR, E_USER_WARNING, E_USER_NOTICE);
$err = "<errorentry>\n";
$err .= "\t<datetime>" . $dt . "</datetime>\n";
$err .= "\t<errornum>" . $errno . "</errornum>\n";
$err .= "\t<errortype>" . $errortype[$errno] . "</errortype>\n";
$err .= "\t<errormsg>" . $errmsg . "</errormsg>\n";
$err .= "\t<scriptname>" . $filename . "</scriptname>\n";
$err .= "\t<scriptlinenum>" . $linenum . "</scriptlinenum>\n";
if (in_array($errno, $user_errors)) {
$err .= "\t<vartrace>" . wddx_serialize_value($vars, "Variables") . "</vartrace>\n";
}
$err .= "</errorentry>\n\n";
// for testing
// echo $err;
// save to the error log, and e-mail me if there is a critical user error
error_log($err, 3, "/usr/local/php4/error.log");
if ($errno == E_USER_ERROR) {
mail("phpdev@example.com", "Critical User Error", $err);
}
}
function distance($vect1, $vect2)
{
if (!is_array($vect1) || !is_array($vect2)) {
trigger_error("Incorrect parameters, arrays expected", E_USER_ERROR);
return NULL;
}
if (count($vect1) != count($vect2)) {
trigger_error("Vectors need to be of the same size", E_USER_ERROR);
return NULL;
}
for ($i=0; $i<count($vect1); $i++) {
$c1 = $vect1[$i]; $c2 = $vect2[$i];
$d = 0.0;
if (!is_numeric($c1)) {
trigger_error("Coordinate $i in vector 1 is not a number, using zero",
E_USER_WARNING);
$c1 = 0.0;
}
if (!is_numeric($c2)) {
trigger_error("Coordinate $i in vector 2 is not a number, using zero",
E_USER_WARNING);
$c2 = 0.0;
}
$d += $c2*$c2 - $c1*$c1;
}
return sqrt($d);
}
$old_error_handler = set_error_handler("userErrorHandler");
// undefined constant, generates a warning
$t = I_AM_NOT_DEFINED;
// define some "vectors"
$a = array(2, 3, "foo");
$b = array(5.5, 4.3, -1.6);
$c = array(1, -3);
// generate a user error
$t1 = distance($c, $b) . "\n";
// generate another user error
$t2 = distance($b, "i am not an array") . "\n";
// generate a warning
$t3 = distance($a, $b) . "\n";
?>`

# Patrz także

Patrz także syslog().

Poprzedni | Spis treści | Następny
enchant_dict_suggest | Początek rozdziału | debug_backtrace