Apache2::ServerUtil.3pm - Online Linux Manual Page

docs::api::Apache2::ServerUtil - Online Linux Manual PageSection : 3
Updated : 2021-01-26
Source : perl v5.32.1
Note : User Contributed Perl Documentation

NAMEApache2::ServerUtil − Perl API for Apache server record utils

Synopsis use Apache2::ServerUtil (); $s = Apache2::ServerUtil−>server; # push config $s−>add_config(['ServerTokens off']); # add components to the Server signature $s−>add_version_component("MyModule/1.234"); # access PerlSetVar/PerlAddVar values my $srv_cfg = $s−>dir_config; # check command line defines print "this is mp2" if Apache2::ServerUtil::exists_config_define('MODPERL2'); # get PerlChildExitHandler configured handlers @handlers = @{ $s−>get_handlers('PerlChildExitHandler') || []}; # server build and version info: $when_built = Apache2::ServerUtil::get_server_built(); $description = Apache2::ServerUtil::get_server_description(); $banner = Apache2::ServerUtil::get_server_banner(); # ServerRoot value $server_root = Apache2::ServerUtil::server_root(); # get 'conf/' dir path (avoid using this function!) my $dir = Apache2::ServerUtil::server_root_relative($r−>pool, 'conf'); # set child_exit handlers $r−>set_handlers(PerlChildExitHandler => \&handler); # server level PerlOptions flags lookup $s−>push_handlers(ChildExit => \&child_exit) if $s−>is_perl_option_enabled('ChildExit'); # extend HTTP to support a new method $s−>method_register('NEWGET'); # register server shutdown callback Apache2::ServerUtil::server_shutdown_register_cleanup(sub { Apache2::Const::OK }); # do something only when the server restarts my $cnt = Apache2::ServerUtil::restart_count(); do_something_once() if $cnt > 1; # get the resolved ids from Group and User entries my $user_id = Apache2::ServerUtil−>user_id; my $group_id = Apache2::ServerUtil−>group_id;

DescriptionApache2::ServerUtil provides the Apache server object utilities API.

Methods APIApache2::ServerUtil provides the following functions and/or methods:

add_configDynamically add Apache configuration: $s−>add_config($lines); obj: $s ( Apache2::ServerRec object ) arg1: $lines ( ARRAY ref ) An ARRAY reference containing configuration lines per element, without the new line terminators. ret: no return value since: 2.0.00 See also: $r−>add_config For example: Add a configuration section at the server startup (e.g. from startup.pl): use Apache2::ServerUtil (); my $conf = <<'EOC'; PerlModule Apache2::MyExample <Location /perl> SetHandler perl−script PerlResponseHandler Apache2::MyExample </Location> EOC Apache2::ServerUtil−>server−>add_config([split /\n/, $conf]);

add_version_componentAdd a component to the version string $s−>add_version_component($component); obj: $s ( Apache2::ServerRec object ) arg1: $component ( string ) The string component to add ret: no return value since: 2.0.00 This function is usually used by modules to advertise themselves to the world. It's picked up by such statistics collectors, like netcraft.com, which accomplish that by connecting to various servers and grabbing the server version response header (Server). Some servers choose to fully or partially conceal that header. This method should be invoked in the PerlPostConfigHandler phase, which will ensure that the Apache core version number will appear first. For example let's add a component ‟Hikers, Inc/0.99999” to the server string at the server startup: use Apache2::ServerUtil (); use Apache2::Const −compile => 'OK'; Apache2::ServerUtil−>server−>push_handlers( PerlPostConfigHandler => \&add_my_version); sub add_my_version { my ($conf_pool, $log_pool, $temp_pool, $s) = @_; $s−>add_version_component("Hikers, Inc/0.99999"); return Apache2::Const::OK; } or of course you could register the PerlPostConfigHandler handler directly in httpd.conf Now when the server starts, you will something like: [Thu Jul 15 12:15:28 2004] [notice] Apache/2.0.51−dev (Unix) mod_perl/1.99_15−dev Perl/v5.8.5 Hikers, Inc/0.99999 configured −− resuming normal operations Also remember that the ServerTokens directive value controls whether the component information is displayed or not.

dir_config$s−>dir_config() provides an interface for the per-server variables specified by the PerlSetVar and PerlAddVar directives, and also can be manipulated via the APR::Table methods. $table = $s−>dir_config(); $value = $s−>dir_config($key); @values = $s−>dir_config−>get($key); $s−>dir_config($key, $val); obj: $s ( Apache2::ServerRec object ) opt arg2: $key ( string ) Key string opt arg3: $val ( string ) Value string ret: ... Depends on the passed arguments, see further discussion since: 2.0.00 The keys are case-insensitive. $t = $s−>dir_config(); dir_config() called in a scalar context without the $key argument returns a HASH reference blessed into the APR::Table class. This object can be manipulated via the APR::Table methods. For available methods see APR::Table. @values = $s−>dir_config−>get($key); To receive a list of values you must use get() method from the APR::Table class. $value = $s−>dir_config($key); If the $key argument is passed in the scalar context only a single value will be returned. Since the table preserves the insertion order, if there is more than one value for the same key, the oldest value assosiated with the desired key is returned. Calling in the scalar context is also much faster, as it'll stop searching the table as soon as the first match happens. $s−>dir_config($key => $val); If the $key and the $val arguments are used, the set() operation will happen: all existing values associated with the key $key (and the key itself) will be deleted and $value will be placed instead. $s−>dir_config($key => undef); If $val is undef the unset() operation will happen: all existing values associated with the key $key (and the key itself) will be deleted.

exists_config_defineCheck for a definition from the server startup command line (e.g. −DMODPERL2) $result = Apache2::ServerUtil::exists_config_define($name); arg1: $name ( string ) The define string to check for ret: $result ( boolean ) true if defined, false otherwise since: 2.0.00 For example: print "this is mp2" if Apache2::ServerUtil::exists_config_define('MODPERL2');

get_handlersReturns a reference to a list of handlers enabled for a given phase. $handlers_list = $s−>get_handlers($hook_name); obj: $s ( Apache2::ServerRec object ) arg1: $hook_name ( string ) a string representing the phase to handle. ret: $handlers_list (ref to an ARRAY of CODE refs) a list of references to the handler subroutines since: 2.0.00 See also: $r−>add_config For example: A list of handlers configured to run at the child_exit phase: @handlers = @{ $s−>get_handlers('PerlChildExitHandler') || []};

get_server_builtGet the date and time that the server was built $when_built = Apache2::ServerUtil::get_server_built(); ret: $when_built ( string ) The server build time string since: 2.0.00

get_server_versionGet the server version string $version = Apache2::ServerUtil::get_server_version(); This function is deprecated. Use get_server_banner() instead. ret: $version ( string ) The server version string since: 2.0.00

get_server_bannerGet the server banner $banner = Apache2::ServerUtil::get_server_banner(); ret: $banner ( string ) The server banner since: 2.0.4

get_server_descriptionGet the server description $description = Apache2::ServerUtil::get_server_description(); ret: $description ( string ) The server description since: 2.0.4

group_idGet the group id corresponding to the Group directive in httpd.conf: $gid = Apache2::ServerUtil−>group_id; obj: Apache2::ServerUtil (class name) ret: $gid ( integer ) On Unix platforms returns the gid corresponding to the value used in the Group directive in httpd.conf. On other platforms returns 0. since: 2.0.03

is_perl_option_enabledcheck whether a server level PerlOptions flag is enabled or not. $result = $s−>is_perl_option_enabled($flag); obj: $s ( Apache2::ServerRec object ) arg1: $flag ( string ) ret: $result ( boolean ) since: 2.0.00 For example to check whether the ChildExit hook is enabled (which can be disabled with PerlOptions −ChildExit) and configure some handlers to run if enabled: $s−>push_handlers(ChildExit => \&child_exit) if $s−>is_perl_option_enabled('ChildExit'); See also: PerlOptions and the equivalent function for directory level PerlOptions flags.

method_registerRegister a new request method, and return the offset that will be associated with that method. $offset = $s−>method_register($methname); obj: $s ( Apache2::ServerRec object ) arg1: $methname ( string ) The name of the new method to register (in addition to the already supported GET, HEAD, etc.) ret: $offset ( integer ) An int value representing an offset into a bitmask. You can probably ignore it. since: 2.0.00 This method allows you to extend the HTTP protocol to support new methods, which fit the HTTP paradigm. Of course you will need to write a client that understands that protocol extension. For a good example, refer to the MyApache2::SendEmail example presented in the PerlHeaderParserHandler section, which demonstrates how a new method EMAIL is registered and used.

push_handlersAdd one or more handlers to a list of handlers to be called for a given phase. $ok = $s−>push_handlers($hook_name => \&handler); $ok = $s−>push_handlers($hook_name => [\&handler, \&handler2]); obj: $s ( Apache2::ServerRec object ) arg1: $hook_name ( string ) the phase to add the handlers to arg2: $handlers ( CODE ref or SUB name or an ARRAY ref ) a single handler CODE reference or just a name of the subroutine (fully qualified unless defined in the current package). if more than one passed, use a reference to an array of CODE refs and/or subroutine names. ret: $ok ( boolean ) returns a true value on success, otherwise a false value since: 2.0.00 See also: $r−>add_config Examples: A single handler: $s−>push_handlers(PerlChildExitHandler => \&handler); Multiple handlers: $s−>push_handlers(PerlChildExitHandler => ['Foo::Bar::handler', \&handler2]); Anonymous functions: $s−>push_handlers(PerlLogHandler => sub { return Apache2::Const::OK });

restart_countHow many times the server was restarted. $restart_count = Apache2::ServerUtil::restart_count(); ret: restart_count ( number ) since: 2.0.00 The following demonstration should make it clear what values to expect from this function. Let's add the following code to startup.pl, so it's run every time httpd.conf is parsed: use Apache2::ServerUtil (); my $cnt = Apache2::ServerUtil::restart_count(); open my $fh, ">>/tmp/out" or die "$!"; print $fh "cnt: $cnt\n"; close $fh; Now let's run a series of server starts and restarts and look at what is logged into /tmp/out: % httpd −k start cnt: 1 cnt: 2 % httpd −k graceful cnt: 1 cnt: 3 % httpd −k graceful cnt: 1 cnt: 4 % httpd −k stop cnt: 1 Remembering that Apache restarts itself immediately after starting, we can see that the restart_count goes from 1 to 2 during the server start. Moreover we can see that every operation forces the parsing of httpd.conf and therefore reinitialization of mod_perl (and running all the code found in httpd.conf). This happens even when the server is shutdown via httpd −k stop. What conclusions can be drawn from this demonstration: • Apache2::ServerUtil::restart_count() returns 1 every time some −k command is passed to Apache (or kill −USR1 or some alternative signal is received). • At all other times the count will be 2 or higher. So for example on graceful restart the count will be 3 or higher. For example if you want to run something every time httpd −k is run you just need to check whether restart_count() returns 1: my $cnt = Apache2::ServerUtil::restart_count(); do_something() if $cnt == 1; To do something only when server restarts (httpd −k start or httpd −k graceful), check whether restart_count() is bigger than 1: my $cnt = Apache2::ServerUtil::restart_count(); do_something() if $cnt > 1;

serverGet the main server's object $main_s = Apache2::ServerUtil−>server(); obj: Apache2::ServerUtil (class name) ret: $main_s ( Apache2::ServerRec object ) since: 2.0.00

server_rootreturns the value set by the top-level ServerRoot directive. $server_root = Apache2::ServerUtil::server_root(); ret: $server_root ( string ) since: 2.0.00

server_root_relativeReturns the canonical form of the filename made absolute to ServerRoot: $path = Apache2::ServerUtil::server_root_relative($pool, $fname); arg1: $pool ( APR::Pool object ) Make sure that you read the following explanation and understand well which pool object you need to pass before using this function. opt arg2: $fname ( string ) ret: $path ( string ) The concatenation of ServerRoot and the $fname. If $fname is not specified, the value of ServerRoot is returned with a trailing /. (it's the same as using '' as $fname's value). since: 2.0.00 $fname is appended to the value of ServerRoot and returned. For example: my $dir = Apache2::ServerUtil::server_root_relative($r−>pool, 'logs'); You must be extra-careful when using this function. If you aren't sure what you are doing don't use it. It's much safer to build the path by yourself using use Apache2::ServerUtil::server_root(), For example: use File::Spec::Functions qw(catfile); my $path = catfile Apache2::ServerUtil::server_root, qw(t logs); In this example, no memory allocation happens on the Apache-side and you aren't risking to get a memory leak. The problem with server_root_relative is that Apache allocates memory to concatenate the path string. The memory is allocated from the pool object. If you call this method on the server pool object it'll allocate the memory from it. If you do that at the server startup, it's perfectly right, since you will do that only once. However if you do that from within a request or a connection handler, you create a memory leak every time it is called \*(-- as the memory gets allocated from the server pool, it will be freed only when the server is shutdown. Therefore if you need to build a relative to the root server path for the duration of the request, use the request pool: use Apache2::RequestRec (); Apache2::ServerUtil::server_root_relative($r−>pool, $fname); If you need to have the path for the duration of a connection (e.g. inside a protocol handler), you should use: use Apache2::Connection (); Apache2::ServerUtil::server_root_relative($c−>pool, $fname); And if you want it for the scope of the server file: use Apache2::Process (); use Apache2::ServerUtil (); Apache2::ServerUtil::server_root_relative($s−>process−>pool, $fname); Moreover, you could have encountered the opposite problem, where you have used a short-lived pool object to construct the path, but tried to use the resulting path variable, when that pool has been destructed already. In order to avoid mysterious segmentation faults, mod_perl does a wasteful copy of the path string when returning it to you \*(-- another reason to avoid using this function.

server_shutdown_cleanup_registerRegister server shutdown cleanup callback: Apache2::ServerUtil::server_shutdown_cleanup_register($sub); arg1: $sub ( CODE ref or SUB name ) ret: no return value since: 2.0.00 This function can be used to register a callback to be run once at the server shutdown (compared to PerlChildExitHandler which will execute the callback for each exiting child process). For example in order to arrange the function do_my_cleanups() to be run every time the server shuts down (or restarts), run the following code at the server startup: Apache2::ServerUtil::server_shutdown_cleanup_register(\&do_my_cleanups); It's necessary to run this code at the server startup (normally startup.pl). The function will croak if run after the PerlPostConfigHandler phase. Values returned from cleanup functions are ignored. If a cleanup dies the exception is stringified and passed to warn(). Usually, this results in printing it to the error_log.

set_handlersSet a list of handlers to be called for a given phase. Any previously set handlers are forgotten. $ok = $s−>set_handlers($hook_name => \&handler); $ok = $s−>set_handlers($hook_name => [\&handler, \&handler2]); $ok = $s−>set_handlers($hook_name => []); $ok = $s−>set_handlers($hook_name => undef); obj: $s ( Apache2::ServerRec object ) arg1: $hook_name ( string ) the phase to set the handlers in arg2: $handlers ( CODE ref or SUB name or an ARRAY ref ) a reference to a single handler CODE reference or just a name of the subroutine (fully qualified unless defined in the current package). if more than one passed, use a reference to an array of CODE refs and/or subroutine names. if the argument is undef or [] the list of handlers is reset to zero. ret: $ok ( boolean ) returns a true value on success, otherwise a false value since: 2.0.00 See also: $r−>add_config Examples: A single handler: $r−>set_handlers(PerlChildExitHandler => \&handler); Multiple handlers: $r−>set_handlers(PerlFixupHandler => ['Foo::Bar::handler', \&handler2]); Anonymous functions: $r−>set_handlers(PerlLogHandler => sub { return Apache2::Const::OK }); Reset any previously set handlers: $r−>set_handlers(PerlCleanupHandler => []); or $r−>set_handlers(PerlCleanupHandler => undef);

user_idGet the user id corresponding to the User directive in httpd.conf: $uid = Apache2::ServerUtil−>user_id; obj: Apache2::ServerUtil (class name) ret: $uid ( integer ) On Unix platforms returns the uid corresponding to the value used in the User directive in httpd.conf. On other platforms returns 0. since: 2.0.03

Unsupported APIApache2::ServerUtil also provides auto-generated Perl interface for a few other methods which aren't tested at the moment and therefore their API is a subject to change. These methods will be finalized later as a need arises. If you want to rely on any of the following methods please contact the the mod_perl development mailing list so we can help each other take the steps necessary to shift the method to an officially supported API.

error_log2stderrStart sending STDERR to the error_log file $s−>error_log2stderr(); obj: $s ( Apache2::ServerRec object ) The current server ret: no return value since: 2.0.00 This method may prove useful if you want to start redirecting STDERR to the error_log file before Apache does that on the startup.