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-ori
ented 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 sev
eral new methods 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 function, 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 temporary file. It is similar to the tmpnam()
function in the POSIX module, 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 gener
ates a series of filenames using the current process
ID and the $TMPNAM package global. Once a unique name
is found, it is opened for writing, using flags that
will cause the file to be created only if it does not
already exist. This prevents race conditions in which
the function finds what seems to be an unused name,
but someone else claims the same name before it can be
created.
As an added bonus, tmpfile() calls the regis_
ter_cleanup() method behind the scenes to make sure
the file is unlinked after the transaction is fin
ished.
Called in a list context, tmpfile() returns the tempo
rary file name and a filehandle opened for reading and
writing. In a scalar context only the filehandle is
returned.
my($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 memory using the features
of the HTTP/1.1 protocol that provide increased perfor
mance 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 dis
carding is especially important when persistent con
nections 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_con_
ditions() 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.
The last modified time may also be changed using this
method, although update_mtime() method is better
suited to this purpose.
my $date_string = localtime $r->mtime;
$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->filename. 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 modified. 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 specified time is not in the
future. In addition, using set_last_modified() 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 modification 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 cur
rent 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);
2002-04-15 perl v5.6.1 File(3)
