Notices: Avoid accessing offset on null

Thanks to @peterpp at 62017e3.

adminer/include/adminer.inc.php

@@ -667,7 +667,7 @@ class Adminer {
 		global $driver;
 		restart_session();
 		$history = &get_session("queries");
-		if (!$history[$_GET["db"]]) {
+		if (!idx($history, $_GET["db"])) {
 			$history[$_GET["db"]] = array();
 		}
 		if (strlen($query) > 1e6) {

adminer/include/auth.inc.php

@@ -62,7 +62,7 @@ function check_invalid_login() {
 		}
 	}
 	$invalid = ($invalids ? $invalids[$adminer->bruteForceKey()] : array());
-	$next_attempt = ($invalid[1] > 29 ? $invalid[0] - time() : 0); // allow 30 invalid attempts
+	$next_attempt = (idx($invalid, 1) > 29 ? $invalid[0] - time() : 0); // allow 30 invalid attempts
 	if ($next_attempt > 0) { //! do the same with permanent login
 		auth_error(lang('Too many unsuccessful logins, try again in %d minute(s).', ceil($next_attempt / 60)));
 	}

adminer/include/coverage.inc.php

@@ -8,7 +8,7 @@ if (extension_loaded("xdebug") && file_exists(sys_get_temp_dir() . "/adminer.cov
 		$coverage = unserialize(file_get_contents($coverage_filename));
 		foreach (xdebug_get_code_coverage() as $filename => $lines) {
 			foreach ($lines as $l => $val) {
-				if (!$coverage[$filename][$l] || $val > 0) {
+				if (!idx($coverage[$filename], $l) || $val > 0) {
 					$coverage[$filename][$l] = $val;
 				}
 			}

adminer/include/design.inc.php

@@ -182,7 +182,7 @@ function get_nonce() {
 function page_messages($error) {
 	global $adminer;
 	$uri = preg_replace('~^[^?]*~', '', $_SERVER["REQUEST_URI"]);
-	$messages = $_SESSION["messages"][$uri];
+	$messages = idx($_SESSION["messages"], $uri);
 	if ($messages) {
 		echo "<div class='message'>" . implode("</div>\n<div class='message'>", $messages) . "</div>" . script("messagesPrint();");
 		unset($_SESSION["messages"][$uri]);

adminer/include/editing.inc.php

@@ -353,7 +353,7 @@ function edit_fields($fields, $collations, $type = "TABLE", $foreign_keys = arra
 	foreach ($fields as $i => $field) {
 		$i++;
 		$orig = $field[($_POST ? "orig" : "field")];
-		$display = (isset($_POST["add"][$i-1]) || (isset($field["field"]) && !$_POST["drop_col"][$i])) && (support("drop_col") || $orig == "");
+		$display = (isset($_POST["add"][$i-1]) || (isset($field["field"]) && !idx($_POST["drop_col"], $i))) && (support("drop_col") || $orig == "");
 		echo "<tr" . ($display ? "" : " style='display: none;'") . ">\n";
 		echo ($type == "PROCEDURE" ? "<td>" . html_select("fields[$i][inout]", explode("|", $driver->inout), $field["inout"]) : "") . "<th>";
 		if ($display) {

adminer/include/errors.inc.php

@@ -3,8 +3,7 @@ namespace Adminer;
 
 error_reporting(24575); // all but E_DEPRECATED (overriding mysqli methods without types is deprecated)
 set_error_handler(function ($errno, $errstr) {
-	// "offset on null" mutes $_GET["fields"][0] if there's no ?fields[]= (62017e3 is a wrong fix for this)
 	// "Undefined array key" mutes $_GET["q"] if there's no ?q=
 	// "Undefined offset" and "Undefined index" are older messages for the same thing
-	return !!preg_match('~^(Trying to access array offset on( value of type)? null|Undefined (array key|offset|index))~', $errstr);
+	return !!preg_match('~^(Undefined (array key|offset|index))~', $errstr);
 }, E_WARNING | E_NOTICE); // warning since PHP 8.0

adminer/include/functions.inc.php

@@ -65,6 +65,16 @@ function escape_string($val) {
 	return substr(q($val), 1, -1);
 }
 
+/** Get a possibly missing item from a possibly missing array
+* @param array|null
+* @param string|int
+* @param mixed
+* @return mixed
+*/
+function idx($array, $key, $default = null) {
+	return ($array && array_key_exists($key, $array) ? $array[$key] : $default);
+}
+
 /** Remove non-digits from a string
 * @param string
 * @return string
@@ -302,12 +312,13 @@ function where($where, $fields = array()) {
 	foreach ((array) $where["where"] as $key => $val) {
 		$key = bracket_escape($key, 1); // 1 - back
 		$column = escape_key($key);
-		$field_type = $fields[$key]["type"];
+		$field = ($fields ? $fields[$key] : array());
+		$field_type = $field["type"];
 		$return[] = $column
 			. (JUSH == "sql" && $field_type == "json" ? " = CAST(" . q($val) . " AS JSON)"
 				: (JUSH == "sql" && is_numeric($val) && preg_match('~\.~', $val) ? " LIKE " . q($val) // LIKE because of floats but slow with ints
 				: (JUSH == "mssql" && strpos($field_type, "datetime") === false ? " LIKE " . q(preg_replace('~[_%[]~', '[\0]', $val)) // LIKE because of text but it does not work with datetime
-				: " = " . unconvert_field($fields[$key], q($val)))))
+				: " = " . unconvert_field($field, q($val)))))
 		; //! enum and set
 		if (JUSH == "sql" && preg_match('~char|text~', $field_type) && preg_match("~[^ -@]~", $val)) { // not just [a-z] to catch non-ASCII characters
 			$return[] = "$column = " . q($val) . " COLLATE " . charset($connection) . "_bin";

adminer/include/html.inc.php

@@ -352,7 +352,7 @@ function process_input($field) {
 		return null;
 	}
 	$idf = bracket_escape($field["field"]);
-	$function = $_POST["function"][$idf];
+	$function = idx($_POST["function"], $idf);
 	$value = $_POST["fields"][$idf];
 	if ($field["type"] == "enum" || $driver->enumLength($field)) {
 		if ($value == -1) {
@@ -453,7 +453,7 @@ function edit_form($table, $fields, $row, $update) {
 		$autofocus = !$_POST;
 		foreach ($fields as $name => $field) {
 			echo "<tr><th>" . $adminer->fieldName($field);
-			$default = $_GET["set"][bracket_escape($name)];
+			$default = idx($_GET["set"], bracket_escape($name));
 			if ($default === null) {
 				$default = $field["default"];
 				if ($field["type"] == "bit" && preg_match("~^b'([01]*)'\$~", $default, $regs)) {
@@ -477,7 +477,7 @@ function edit_form($table, $fields, $row, $update) {
 				$value = $adminer->editVal($value, $field);
 			}
 			$function = ($_POST["save"]
-				? (string) $_POST["function"][$name]
+				? idx($_POST["function"], $name, "")
 				: ($update && preg_match('~^CURRENT_TIMESTAMP~i', $field["on_update"])
 					? "now"
 					: ($value === false ? null : ($value !== null ? '' : 'NULL'))