From 2dc420ccf0d0ed17636b3f16cdcaac700bade394 Mon Sep 17 00:00:00 2001
From: Havoc Pennington <hp@pobox.com>
Date: Mon, 9 Apr 2012 19:18:46 -0400
Subject: [PATCH] If include statements from a cycle, throw a nicer error

---
 NEWS.md                                       |  2 ++
 .../com/typesafe/config/impl/Parseable.java   | 34 +++++++++++++++++--
 config/src/test/resources/cycle.conf          |  1 +
 .../typesafe/config/impl/PublicApiTest.scala  |  9 +++++
 4 files changed, 44 insertions(+), 2 deletions(-)
 create mode 100644 config/src/test/resources/cycle.conf

diff --git a/NEWS.md b/NEWS.md
index ad00b495..1d12a8ce 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -30,6 +30,8 @@
    implement ConfigIncluderFile, ConfigIncluderURL, and
    ConfigIncluderClasspath. You should also use
    ConfigIncludeContext.parseOptions() if appropriate.
+ - cycles in include statements (self-includes) are now detected
+   and result in a nicer error instead of stack overflow
  - the serialization format has changed for a Config that has not
    had resolve() called on it. The library can still deserialize
    the old format, but old versions of the library will not be
diff --git a/config/src/main/java/com/typesafe/config/impl/Parseable.java b/config/src/main/java/com/typesafe/config/impl/Parseable.java
index 09536fa1..95bf8b54 100644
--- a/config/src/main/java/com/typesafe/config/impl/Parseable.java
+++ b/config/src/main/java/com/typesafe/config/impl/Parseable.java
@@ -20,6 +20,7 @@ import java.net.URISyntaxException;
 import java.net.URL;
 import java.util.Enumeration;
 import java.util.Iterator;
+import java.util.LinkedList;
 import java.util.Properties;
 
 import com.typesafe.config.ConfigException;
@@ -43,8 +44,16 @@ public abstract class Parseable implements ConfigParseable {
     private ConfigParseOptions initialOptions;
     private ConfigOrigin initialOrigin;
 
-    protected Parseable() {
+    private static final ThreadLocal<LinkedList<Parseable>> parseStack = new ThreadLocal<LinkedList<Parseable>>() {
+        @Override
+        protected LinkedList<Parseable> initialValue() {
+            return new LinkedList<Parseable>();
+        }
+    };
 
+    private static final int MAX_INCLUDE_DEPTH = 50;
+
+    protected Parseable() {
     }
 
     private ConfigParseOptions fixupOptions(ConfigParseOptions baseOptions) {
@@ -122,7 +131,23 @@ public abstract class Parseable implements ConfigParseable {
 
     @Override
     public ConfigObject parse(ConfigParseOptions baseOptions) {
-        return forceParsedToObject(parseValue(baseOptions));
+
+        LinkedList<Parseable> stack = parseStack.get();
+        if (stack.size() >= MAX_INCLUDE_DEPTH) {
+            throw new ConfigException.Parse(initialOrigin, "include statements nested more than "
+                    + MAX_INCLUDE_DEPTH
+                    + " times, you probably have a cycle in your includes. Trace: " + stack);
+        }
+
+        stack.addFirst(this);
+        try {
+            return forceParsedToObject(parseValue(baseOptions));
+        } finally {
+            stack.removeFirst();
+            if (stack.isEmpty()) {
+                parseStack.remove();
+            }
+        }
     }
 
     final AbstractConfigValue parseValue(ConfigParseOptions baseOptions) {
@@ -350,6 +375,11 @@ public abstract class Parseable implements ConfigParseable {
         protected ConfigOrigin createOrigin() {
             return SimpleConfigOrigin.newSimple("String");
         }
+
+        @Override
+        public String toString() {
+            return getClass().getSimpleName() + "(" + input + ")";
+        }
     }
 
     public static Parseable newString(String input, ConfigParseOptions options) {
diff --git a/config/src/test/resources/cycle.conf b/config/src/test/resources/cycle.conf
new file mode 100644
index 00000000..a0772910
--- /dev/null
+++ b/config/src/test/resources/cycle.conf
@@ -0,0 +1 @@
+include "cycle.conf"
diff --git a/config/src/test/scala/com/typesafe/config/impl/PublicApiTest.scala b/config/src/test/scala/com/typesafe/config/impl/PublicApiTest.scala
index 24aaa30b..205c5a07 100644
--- a/config/src/test/scala/com/typesafe/config/impl/PublicApiTest.scala
+++ b/config/src/test/scala/com/typesafe/config/impl/PublicApiTest.scala
@@ -817,4 +817,13 @@ class PublicApiTest extends TestUtils {
         assertTrue("cache was dropped when switching loaders", load3 ne load7)
         assertEquals(load3, load7)
     }
+
+    @Test
+    def detectIncludeCycle() {
+        val e = intercept[ConfigException.Parse] {
+            ConfigFactory.load("cycle")
+        }
+
+        assertTrue("wrong exception: " + e.getMessage, e.getMessage.contains("include statements nested"))
+    }
 }