File(3) User Contributed Perl Documentation File(3)NAMEApache::File - advanced functions for manipulating files at the server
side
SYNOPSIS
use Apache::File ();
DESCRIPTIONApache::File does two things: it provides an object-oriented interface
to filehandles similar to Perl's standard IO::File class. While the
Apache::File module does not provide all the functionality of IO::File,
its methods are approximately twice as fast as the equivalent IO::File
methods. Secondly, when you use Apache::File, it adds several new meth-
ods to the Apache class which provide support for handling files under
the HTTP/1.1 protocol.
Apache::File methodsnew()
This method creates a new filehandle, returning the filehandle
object on success, undef on failure. If an additional argument is
given, it will be passed to the open() method automatically.
use Apache::File ();
my $fh = Apache::File->new;
my $fh = Apache::File->new($filename) or die "Can't open $filename $!";
open()
Given an Apache::File object previously created with new(), this
method opens a file and associates it with the object. The open()
method accepts the same types of arguments as the standard Perl
open() function, including support for file modes.
$fh->open($filename);
$fh->open(">$out_file");
$fh->open("|$program");
close()
The close() method is equivalent to the Perl builtin close func-
tion, returns true upon success, false upon failure.
$fh->close or die "Can't close $filename $!";
tmpfile()
The tmpfile() method is responsible for opening up a unique tempo-
rary file. It is similar to the tmpnam() function in the POSIX mod-
ule, but doesn't come with all the memory overhead that loading
POSIX does. It will choose a suitable temporary directory (which
must be writable by the Web server process). It then generates a
series of filenames using the current process ID and the $TMPNAM
package global. Once a unique name is found, it is opened for writ-
ing, using flags that will cause the file to be created only if it
does not already exist. This prevents race conditions in which the
function finds what seems to be an unused name, but someone else
claims the same name before it can be created.
As an added bonus, tmpfile() calls the register_cleanup() method
behind the scenes to make sure the file is unlinked after the
transaction is finished.
Called in a list context, tmpfile() returns the temporary file name
and a filehandle opened for reading and writing. In a scalar con-
text only the filehandle is returned.
my($tmpnam, $fh) = Apache::File->tmpfile;
my $fh = Apache::File->tmpfile;
Apache Methods added by Apache::File
When a handler pulls in Apache::File, the module adds a number of new
methods to the Apache request object. These methods are generally of
interest to handlers that wish to serve static files from disk or mem-
ory using the features of the HTTP/1.1 protocol that provide increased
performance through client-side document caching.
$r->discard_request_body()
This method tests for the existence of a request body and if
present, simply throws away the data. This discarding is especially
important when persistent connections are being used, so that the
request body will not be attached to the next request. If the
request is malformed, an error code will be returned, which the
module handler should propagate back to Apache.
if ((my $rc = $r->discard_request_body) != OK) {
return $rc;
}
$r->meets_conditions()
In the interest of HTTP/1.1 compliance, the meets_conditions()
method is used to implement ``conditional GET'' rules. These rules
include inspection of client headers, including If-Modified-Since,
If-Unmodified-Since, If-Match and If-None-Match.
As far as Apache modules are concerned, they need only check the
return value of this method before sending a request body. If the
return value is anything other than OK, the module should return
from the handler with that value. A common return value other than
OK is HTTP_NOT_MODIFIED, which is sent when the document is already
cached on the client side, and has not changed since it was cached.
if((my $rc = $r->meets_conditions) != OK) {
return $rc;
}
#else ... go and send the response body ...
$r->mtime()
This method returns the last modified time of the requested file,
expressed as seconds since the epoch.
my $date_string = localtime $r->mtime;
To change the last modified time use the "update_mtime()" method.
$r->set_content_length()
This method sets the outgoing Content-length header based on its
argument, which should be expressed in byte units. If no argument
is specified, the method will use the size returned by $r->file-
name. This method is a bit faster and more concise than setting
Content-length in the headers_out table yourself.
$r->set_content_length;
$r->set_content_length(-s $r->finfo); #same as above
$r->set_content_length(-s $filename);
$r->set_etag()
This method is used to set the outgoing ETag header corresponding
to the requested file. ETag is an opaque string that identifies the
currrent version of the file and changes whenever the file is modi-
fied. This string is tested by the meets_conditions() method if the
client provide an If-Match or If-None-Match header.
$r->set_etag;
$r->set_last_modified()
This method is used to set the outgoing Last-Modified header from
the value returned by $r->mtime. The method checks that the speci-
fied time is not in the future. In addition, using set_last_modi-
fied() is faster and more concise than setting Last-Modified in the
headers_out table yourself.
You may provide an optional time argument, in which case the method
will first call the update_mtime() to set the file's last modifica-
tion date. It will then set the outgoing Last-Modified header as
before.
$r->update_mtime((stat $r->finfo)[9]);
$r->set_last_modified;
$r->set_last_modified((stat $r->finfo)[9]); #same as the two lines above
$r->update_mtime()
Rather than setting the request record mtime field directly, you
can use the update_mtime() method to change the value of this
field. It will only be updated if the new time is more recent than
the current mtime. If no time argument is present, the default is
the last modified time of $r->filename.
$r->update_mtime;
$r->update_mtime((stat $r->finfo)[9]); #same as above
$r->update_mtime(time);
perl v5.8.8 2007-03-30 File(3)
