Cache.pm

NAME

Netscape::Cache - object class for accessing Netscape cache files

SYNOPSIS

The object oriented interace:

use Netscape::Cache; $cache = new Netscape::Cache; while (defined($url = $cache->next_url)) { print $url, "\n"; } while (defined($o = $cache->next_object)) { print $o->{'URL'}, "\n", $o->{'CACHEFILE'}, "\n", $o->{'LAST_MODIFIED'}, "\n", $o->{'MIME_TYPE'}, "\n"; }

The TIEHASH interface:

use Netscape::Cache; tie %cache, 'Netscape::Cache'; foreach (sort keys %cache) { print $cache{$_}->{URL}, "\n"; }

DESCRIPTION

The Netscape::Cache module implements an object class for accessing the filenames and URLs of the cache files used by the Netscape web browser. You can access the cached URLs offline via Netscape if you set Options->Network Preferences->Verify Document to Never.

Note: You can also use the undocumented pseudo-URLs about:cache, about:memory-cache and about:global-history to access your cache, memory cache and history.

There is also an interface for using tied hashes.

CONSTRUCTOR

$cache = new Netscape::Cache(-cachedir => "$ENV{HOME}/.netscape/cache");

This creates a new instance of the Netscape::Cache object class. The -cachedir argument is optional. By default, the cache directory setting is retrieved from ~/.netscape/preferences.

If the Netscape cache index file does not exist, a warning message will be generated, and the constructor will return undef.

METHODS

The Netscape::Cache class implements the following methods:

rewind - reset cache index to first URL
next_url - get next URL from cache index
next_object - get next URL as a full Netscape::Cache::Object description from cache index
get_object - get the Netscape::Cache::Object description for a given URL

Each of the methods is described separately below..

next_url

$url = $history->next_url;

This method returns the next URL from the cache index. Unlike Netscape::History, this method returns a string and not an URI::URL-like object.

This method is faster than next_object , since it does only evaluate the URL of the cached file.

next_object

$cache->next_object;

This method returns the next URL from the cache index as a Netscape::Cache::Object object. See below for accessing the components (cache filename, content length, mime type and more) of this object.

get_object

$cache->get_object;

This method returns the Netscape::Cache::Object object for a given URL. If the URL does not live in the cache index, then the returned value will be undefined.

delete_object

Deletes URL from cache index and the related file from the cache.

WARNING: Do not use delete_object while in a next_object loop! It is better to collect all objects for delete in a list and do the deletion after the loop, otherwise you can get strange behaviour (e.g. malloc panics).

rewind

$cache->rewind();

This method is used to move the internal pointer of the cache index to the first URL in the cache index. You don't need to bother with this if you have just created the object, but it doesn't harm anything if you do.

Netscape::Cache::Object

next_object and get_object return an object of the class Netscape::Cache::Object . This object is simply a hash, which members have to be accessed directly (no methods).

An example:

$o = $cache->next_object; print $o->{'URL'}, "\n";

URL

The URL of the cached object

CACHEFILE

The filename of the cached URL in the cache directory. To construct the full path use ($cache is a Netscape::Cache object and $o a Netscape::Cache::Object object)

$cache->{'CACHEDIR'} . "/" . $o->{'CACHEFILE'}

CACHEFILE_SIZE

The size of the cache file.

CONTENT_LENGTH

The length of the cache file as specified in the HTTP response header. In general, SIZE and CONTENT_LENGTH are equal. If you interrupt a transfer of a file, only the first part of the file is written to the cache, resulting in a smaller CONTENT_LENGTH than SIZE.

LAST_MODIFIED

The date of last modification of the URL as unix time (seconds since epoch). Use

scalar localtime $o->{'LAST_MODIFIED'}

to get a human readable date.

LAST_VISITED

The date of last visit.

EXPIRE_DATE

If defined, the date of expiry for the URL.

MIME_TYPE

The MIME type of the URL (eg. text/html or image/jpeg).

ENCODING

The encoding of the URL (eg. x-gzip for gzipped data).

CHARSET

The charset of the URL (eg. iso-8859-1).

AN EXAMPLE PROGRAM

This program loops through all cache objects and prints a HTML-ified list. The list ist sorted by URL, but you can sort it by last visit date or size, too.

use Netscape::Cache; $cache = new Netscape::Cache; while ($o = $cache->next_object) { push(@url, $o); } # sort by name @url = sort {$a->{'URL'} cmp $b->{'URL'}} @url; # sort by visit time #@url = sort {$b->{'LAST_VISITED'} <=> $a->{'LAST_VISITED'}} @url; # sort by mime type #@url = sort {$a->{'MIME_TYPE'} cmp $b->{'MIME_TYPE'}} @url; # sort by size #@url = sort {$b->{'CACHEFILE_SIZE'} <=> $a->{'CACHEFILE_SIZE'}} @url; print "<ul>\n"; foreach (@url) { print "<li><a href=\"file:", $cache->{'CACHEDIR'}, "/", $_->{'CACHEFILE'}, "\">", $_->{'URL'}, "</a> ", scalar localtime $_->{'LAST_VISITED'}, "<br>", "type: ", $_->{'MIME_TYPE'}, ",size: ", $_->{'CACHEFILE_SIZE'}, "\n"; } print "</ul>\n";

ENVIRONMENT

The Netscape::Cache module examines the following environment variables:

HOME: Home directory of the user, used to find Netscape's preferences ($HOME/.netscape). Otherwise, if not set, retrieve the home directory from the passwd file.

BUGS

There are still some unknown fields (_XXX_FLAG_{1,2,3}).

You can't use delete_object while looping with next_object . See the question "What happens if I add or remove keys from a hash while iterating over it?" in perlfaq4.

keys() or each() on the tied hash are slower than the object oriented equivalents next_object or next_url .

AUTHOR

Slaven Rezic <eserte@cs.tu-berlin.de>