File(3p)              User Contributed Perl Documentation             File(3p)



NAME
       Apache::File - advanced functions for manipulating files at the server
       side

SYNOPSIS
          use Apache::File ();

DESCRIPTION
       Apache::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
       methods to the Apache class which provide support for handling files
       under the HTTP/1.1 protocol.

Apache::File methods
       new()
           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 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
           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 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
           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 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->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 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 v5.12.2                      2004-05-14                          File(3p)
