Update everything to work with PHP 8.3

A lot of stuff has been deprecated or made stricter with return type annotations. Also, the SimplePie ad-hoc autoloader stopped working, so I switched it to use [Composer](https://getcomposer.org/) to manage the external dependencies.

I have verified that this still works with PHP 8.1, although I cannot guarantee it on older versions.

.gitignore

@@ -7,3 +7,5 @@ fof-install.log
 *~
 cookies.txt
 .idea
+
+/vendor/

README.md

@@ -50,16 +50,19 @@ FeedOnFeeds requires:
   and more are easy to add)
 * Specific features may require specific PHP extensions; it is highly
   recommended (but not required) that you have *Xlib*, *cURL*, and *iconv*.
+* [Composer](https://getcomposer.org/)
 
-To install, simply download a snapshot or clone from your favorite git
-repository. Then copy `fof-config.php.dist` to `fof-config.php` and edit
-it as appropriate for your setup. If you're on shared hosting, be sure
-to point `FOF_DATA_PATH` to somewhere in your home directory.
+To install:
 
-After that, point a web browser to `install.php`. For example, if you've
-installed FeedOnFeeds at `http://example.com/fof`, go to
-`http://example.com/fof/install.php` and then everything should be set
-up automatically.
+1. Download a snapshot or clone from your favorite git repository
+2. Run `composer install` to install/update the library dependencies
+3. Copy `fof-config.php.dist` to `fof-config.php` and edit it as appropriate for your setup
+  * If you're on shared hosting, be sure to point `FOF_DATA_PATH` to somewhere in your home directory.
+4. Point a web browser to `install.php`
+
+  For example, if you've installed FeedOnFeeds at `http://example.com/fof`, go to
+  `http://example.com/fof/install.php` and then everything should be set
+  up automatically.
 
 ### Which database backend should I use?
 

add.php

@@ -115,16 +115,16 @@
 ?>>no</option>
 </select> items as unread<br><br>
 
-RSS or reddit or weblog URL: <input type="text" name="rss_url" size="40" value="<?php echo htmlentities($url) ?>"><input type="Submit" value="Add a feed"><br><br>
+RSS or reddit or weblog URL: <input type="text" name="rss_url" size="40" value="<?php echo htmlentities($url??"") ?>"><input type="Submit" value="Add a feed"><br><br>
 
-YouTube channel page: <input type="text" name="youtube_channel" size="40" value="<?php echo htmlentities($youtube) ?>"><input type="Submit" value="Subscribe to channel"><br><br>
+YouTube channel page: <input type="text" name="youtube_channel" size="40" value="<?php echo htmlentities($youtube??"") ?>"><input type="Submit" value="Subscribe to channel"><br><br>
 
 OPML URL: <input type="hidden" name="MAX_FILE_SIZE" value="100000">
 
-<input type="text" name="opml_url" size="40" value="<?php echo htmlentities($opml) ?>"><input type="Submit" value="Add feeds from OPML file on the Internet"><br><br>
+<input type="text" name="opml_url" size="40" value="<?php echo htmlentities($opml??"") ?>"><input type="Submit" value="Add feeds from OPML file on the Internet"><br><br>
 
 <input type="hidden" name="MAX_FILE_SIZE" value="100000">
-OPML filename: <input type="file" name="opml_file" size="40" value="<?php echo htmlentities($file) ?>"><input type="Submit" value="Upload an OPML file">
+OPML filename: <input type="file" name="opml_file" size="40" value="<?php echo htmlentities($file??"") ?>"><input type="Submit" value="Upload an OPML file">
 
 </form>
 <hr>

classes/pdolog.php

@@ -17,7 +17,7 @@ public function __construct($dsn, $username=null, $password=null, $driver_option
 		$this->setAttribute(PDO::ATTR_STATEMENT_CLASS, array('PDOStatementLog', array($this)));
 	}
 
-	public function query($query, $fetchMode = null, ...$fetchModeArgs) {
+	public function query($query, $fetchMode = null, ...$fetchModeArgs): PDOStatement|false {
 		if (empty(self::$logfn))
 			return parent::query($query);
 
@@ -28,7 +28,7 @@ public function query($query, $fetchMode = null, ...$fetchModeArgs) {
 		return $result;
 	}
 
-	public function exec($statement) {
+	public function exec($statement): int|false {
 		if (empty(self::$logfn))
 			return parent::exec($statement);
 
@@ -48,17 +48,17 @@ protected function __construct($dbh) {
 		$this->parameters = array();
 	}
 
-	public function bindParam($parameter, &$variable, $data_type=PDO::PARAM_STR, $length=null, $driver_options=null) {
+	public function bindParam($parameter, &$variable, $data_type=PDO::PARAM_STR, $length=null, $driver_options=null): bool {
 		$this->parameters[$parameter] = $variable;
-		parent::bindParam($parameter, $variable, $data_type, $length, $driver_options);
+		return parent::bindParam($parameter, $variable, $data_type, $length, $driver_options);
 	}
 
-	public function bindValue($parameter, $value, $data_type=PDO::PARAM_STR) {
+	public function bindValue($parameter, $value, $data_type=PDO::PARAM_STR): bool {
 		$this->parameters[$parameter] = $value;
-		parent::bindValue($parameter, $value, $data_type);
+		return parent::bindValue($parameter, $value, $data_type);
 	}
 
-	public function execute($input_parameters=null) {
+	public function execute($input_parameters=null): bool {
 		if (empty(PDOLog::$logfn))
 			return parent::execute($input_parameters);
 

composer.json

@@ -0,0 +1,11 @@
+{
+    "name": "feed-on-feeds/feed-on-feeds",
+    "description": "A lightweight server-based RSS feed aggregator and reader",
+    "type": "project",
+    "require": {
+        "simplepie/simplepie": "dev-master",
+        "busybee/urljoin": "dev-main"
+    },
+    "license": "GPL",
+    "minimum-stability": "dev"
+}

fof-db.php

@@ -1254,11 +1254,15 @@ function fof_db_get_subscription_to_tags() {
 	while (($row = fof_db_get_row($statement)) !== false) {
 		$feed_id = $row['feed_id'];
 		$user_id = $row['user_id'];
-		$prefs = unserialize($row['subscription_prefs']);
+		if (isset($row['subscription_prefs'])) {
+			$prefs = unserialize($row['subscription_prefs']);
+		} else {
+			$prefs = [];
+		}
 		if (!isset($r[$feed_id])) {
 			$r[$feed_id] = array();
 		}
-		$r[$feed_id][$user_id] = $prefs['tags'];
+		$r[$feed_id][$user_id] = $prefs['tags'] ?? [];
 	}
 
 	return $r;
@@ -2152,7 +2156,7 @@ function fof_db_prefs_get($user_id) {
 	$result = $statement->execute();
 	$prefs = fof_db_get_row($statement, 'user_prefs', TRUE);
 
-	return unserialize($prefs);
+	return unserialize($prefs || "");
 }
 
 function fof_db_save_prefs($user_id, $prefs) {