From a4fa35db6048f78403177ae5bea3a99dd6323c01 Mon Sep 17 00:00:00 2001
From: Alexander Ebert <ebert@woltlab.com>
Date: Sat, 19 Nov 2016 21:07:36 +0100
Subject: [PATCH] Disallow rebuilding data before encoding conversion

---
 .../files/acp/templates/rebuildData.tpl       | 21 ++++++++++-----
 .../lib/acp/page/RebuildDataPage.class.php    | 26 +++++++++++++++++++
 2 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/wcfsetup/install/files/acp/templates/rebuildData.tpl b/wcfsetup/install/files/acp/templates/rebuildData.tpl
index 9988c47e0d..fc50f88e75 100644
--- a/wcfsetup/install/files/acp/templates/rebuildData.tpl
+++ b/wcfsetup/install/files/acp/templates/rebuildData.tpl
@@ -31,18 +31,25 @@
 	</header>
 	
 	{foreach from=$objectTypes item=objectType}
+		{assign var=_allowRebuild value=true}
+		{if !$convertEncoding && $objectType->objectType != 'com.woltlab.wcf.databaseConvertEncoding'}
+			{assign var=_allowRebuild value=false}
+		{/if}
+		
 		<dl class="wide">
 			<dd>
-				<a class="button small" id="rebuildData{@$objectType->objectTypeID}">{lang}wcf.acp.rebuildData.{@$objectType->objectType}{/lang}</a>
+				<a class="button small{if !$_allowRebuild} disabled{/if}" id="rebuildData{@$objectType->objectTypeID}">{lang}wcf.acp.rebuildData.{@$objectType->objectType}{/lang}</a>
 				<small>{lang}wcf.acp.rebuildData.{@$objectType->objectType}.description{/lang}</small>
 				
-				<script data-relocate="true">
-					$(function() {
-						$('#rebuildData{@$objectType->objectTypeID}').click(function () {
-							new WCF.ACP.Worker('cache', '{@$objectType->className|encodeJS}', '{lang}wcf.acp.rebuildData.{@$objectType->objectType}{/lang}');
+				{if $_allowRebuild}
+					<script data-relocate="true">
+						$(function() {
+							$('#rebuildData{@$objectType->objectTypeID}').click(function () {
+								new WCF.ACP.Worker('cache', '{@$objectType->className|encodeJS}', '{lang}wcf.acp.rebuildData.{@$objectType->objectType}{/lang}');
+							});
 						});
-					});
-				</script>
+					</script>
+				{/if}
 			</dd>
 		</dl>
 	{/foreach}
diff --git a/wcfsetup/install/files/lib/acp/page/RebuildDataPage.class.php b/wcfsetup/install/files/lib/acp/page/RebuildDataPage.class.php
index c15fc4311d..7bcbb888fe 100644
--- a/wcfsetup/install/files/lib/acp/page/RebuildDataPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/RebuildDataPage.class.php
@@ -18,6 +18,12 @@ class RebuildDataPage extends AbstractPage {
 	 */
 	public $activeMenuItem = 'wcf.acp.menu.link.maintenance.rebuildData';
 	
+	/**
+	 * disallow any rebuild actions unless `wcfN_user_storage` uses `utf8mb4`
+	 * @var boolean
+	 */
+	public $convertEncoding = false;
+	
 	/**
 	 * @inheritDoc
 	 */
@@ -66,6 +72,25 @@ class RebuildDataPage extends AbstractPage {
 		if ($row && $row['Value'] == 1) {
 			$this->showInnoDBWarning = true;
 		}
+		
+		// We're disallowing rebuilding any other data unless the
+		// database encoding has been converted to utf8mb4. The
+		// user_storage table is used as a reference, as it is the
+		// last WCF table that holds a varchar column.
+		// 
+		// Querying the columns for each table to reliably detect
+		// the need of an encoding conversion isn't an option, as
+		// it turns out to be super slow to retrieve this data.
+		$sql = "SHOW FULL COLUMNS FROM wcf".WCF_N."_user_storage";
+		$statement = WCF::getDB()->prepareStatement($sql);
+		$statement->execute();
+		while ($row = $statement->fetchArray()) {
+			if ($row['Field'] === 'field') {
+				if (preg_match('~^utf8mb4~', $row['Collation'])) {
+					$this->convertEncoding = true;
+				}
+			}
+		}
 	}
 	
 	/**
@@ -75,6 +100,7 @@ class RebuildDataPage extends AbstractPage {
 		parent::assignVariables();
 		
 		WCF::getTPL()->assign([
+			'convertEncoding' => $this->convertEncoding,
 			'objectTypes' => $this->objectTypes,
 			'showInnoDBWarning' => $this->showInnoDBWarning
 		]);
-- 
2.20.1