From cf717eff0ce3dbac431501000eec52925f507986 Mon Sep 17 00:00:00 2001
From: Thomas Mons <thomas.mons@inthepocket.com>
Date: Tue, 26 Jul 2022 13:00:58 +0200
Subject: [PATCH] Introduced parameter PLANTUML_CONFIG_FILE, that allows to
 specify a PlantUML config file.

---
 README.md                                     |  3 ++
 .../plantuml/servlet/DiagramResponse.java     | 30 ++++++++++++++++++-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 11a731c..1c74c23 100644
--- a/README.md
+++ b/README.md
@@ -115,6 +115,9 @@ You can set all  the following variables:
 * `BASE_URL`
   * PlantUML Base URL path
   * Default value: `ROOT`
+* `PLANTUML_CONFIG_FILE`
+  * Local path to a PlantUML configuration file (identical to the `-config` flag on the CLI)
+  * Default value: `null`
 * `PLANTUML_LIMIT_SIZE`
   * Limits image width and height
   * Default value: `4096`
diff --git a/src/main/java/net/sourceforge/plantuml/servlet/DiagramResponse.java b/src/main/java/net/sourceforge/plantuml/servlet/DiagramResponse.java
index 2113535..b280ca1 100644
--- a/src/main/java/net/sourceforge/plantuml/servlet/DiagramResponse.java
+++ b/src/main/java/net/sourceforge/plantuml/servlet/DiagramResponse.java
@@ -23,11 +23,15 @@
  */
 package net.sourceforge.plantuml.servlet;
 
+import java.io.BufferedReader;
 import java.io.ByteArrayOutputStream;
+import java.io.FileReader;
 import java.io.IOException;
 import java.io.PrintWriter;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import jakarta.servlet.http.HttpServletRequest;
@@ -46,6 +50,7 @@ import net.sourceforge.plantuml.core.Diagram;
 import net.sourceforge.plantuml.core.DiagramDescription;
 import net.sourceforge.plantuml.core.ImageData;
 import net.sourceforge.plantuml.error.PSystemError;
+import net.sourceforge.plantuml.preproc.Defines;
 import net.sourceforge.plantuml.version.Version;
 
 /**
@@ -63,6 +68,8 @@ public class DiagramResponse {
      */
     private static final String POWERED_BY = "PlantUML Version " + Version.versionString();
 
+    private static final List<String> CONFIG = new ArrayList<>();
+
     static {
         OptionFlags.ALLOW_INCLUDE = false;
         if ("true".equalsIgnoreCase(System.getenv("ALLOW_PLANTUML_INCLUDE"))) {
@@ -114,7 +121,28 @@ public class DiagramResponse {
     public void sendDiagram(String uml, int idx) throws IOException {
         response.addHeader("Access-Control-Allow-Origin", "*");
         response.setContentType(getContentType());
-        SourceStringReader reader = new SourceStringReader(uml);
+
+        if (CONFIG.size() == 0 && System.getenv("PLANTUML_CONFIG_FILE") != null) {
+            // Read config
+            final BufferedReader br = new BufferedReader(new FileReader(System.getenv("PLANTUML_CONFIG_FILE")));
+            if (br == null) {
+                return;
+            }
+            try {
+                String s = null;
+                while ((s = br.readLine()) != null) {
+                    CONFIG.add(s);
+                }
+            } finally {
+                br.close();
+            }
+        }
+
+        SourceStringReader reader = new SourceStringReader(Defines.createEmpty(), uml, CONFIG);
+        if (CONFIG.size() > 0 && reader.getBlocks().get(0).getDiagram().getWarningOrError() != null) {
+            reader = new SourceStringReader(uml);
+        }
+
         if (format == FileFormat.BASE64) {
             byte[] imageBytes;
             try (ByteArrayOutputStream outstream = new ByteArrayOutputStream()) {