Catch classes inheriting from themselves in the class linker.

(cherry picked from commit 90328ac545f65759a8e4fb217a75332906795518)

Bug: 28685551
Bug: 27682580
Bug: 28830038

Change-Id: If568013bf3c82c1df9b282522712d9af5ca5945d

7 files changed, 101 insertions, 0 deletions

diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 1835c728b3..8fcb6b25fa 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -5316,6 +5316,19 @@ bool ClassLinker::LoadSuperAndInterfaces(Handle<mirror::Class> klass, const DexF
   const DexFile::ClassDef& class_def = dex_file.GetClassDef(klass->GetDexClassDefIndex());
   uint16_t super_class_idx = class_def.superclass_idx_;
   if (super_class_idx != DexFile::kDexNoIndex16) {
+    // Check that a class does not inherit from itself directly.
+    //
+    // TODO: This is a cheap check to detect the straightforward case
+    // of a class extending itself (b/28685551), but we should do a
+    // proper cycle detection on loaded classes, to detect all cases
+    // of class circularity errors (b/28830038).
+    if (super_class_idx == class_def.class_idx_) {
+      ThrowClassCircularityError(klass.Get(),
+                                 "Class %s extends itself",
+                                 PrettyDescriptor(klass.Get()).c_str());
+      return false;
+    }
+
     mirror::Class* super_class = ResolveType(dex_file, super_class_idx, klass.Get());
     if (super_class == nullptr) {
       DCHECK(Thread::Current()->IsExceptionPending());
diff --git a/runtime/common_throws.cc b/runtime/common_throws.cc
index f8e32c41bf..75cce424e9 100644
--- a/runtime/common_throws.cc
+++ b/runtime/common_throws.cc
@@ -137,6 +137,13 @@ void ThrowClassCircularityError(mirror::Class* c) {
   ThrowException("Ljava/lang/ClassCircularityError;", c, msg.str().c_str());
 }
 
+void ThrowClassCircularityError(mirror::Class* c, const char* fmt, ...) {
+  va_list args;
+  va_start(args, fmt);
+  ThrowException("Ljava/lang/ClassCircularityError;", c, fmt, &args);
+  va_end(args);
+}
+
 // ClassFormatError
 
 void ThrowClassFormatError(mirror::Class* referrer, const char* fmt, ...) {
diff --git a/runtime/common_throws.h b/runtime/common_throws.h
index 39c4e52b15..c3a1f09db3 100644
--- a/runtime/common_throws.h
+++ b/runtime/common_throws.h
@@ -58,6 +58,9 @@ void ThrowArrayStoreException(mirror::Class* element_class, mirror::Class* array
 void ThrowClassCircularityError(mirror::Class* c)
     SHARED_REQUIRES(Locks::mutator_lock_) COLD_ATTR;
 
+void ThrowClassCircularityError(mirror::Class* c, const char* fmt, ...)
+    SHARED_REQUIRES(Locks::mutator_lock_) COLD_ATTR;
+
 // ClassCastException
 
 void ThrowClassCastException(mirror::Class* dest_type, mirror::Class* src_type)
diff --git a/test/804-class-extends-itself/expected.txt b/test/804-class-extends-itself/expected.txt
new file mode 100644
index 0000000000..b98f963ce7
--- /dev/null
+++ b/test/804-class-extends-itself/expected.txt
@@ -0,0 +1,2 @@
+Caught ClassCircularityError
+Done!
diff --git a/test/804-class-extends-itself/info.txt b/test/804-class-extends-itself/info.txt
new file mode 100644
index 0000000000..c48934c21b
--- /dev/null
+++ b/test/804-class-extends-itself/info.txt
@@ -0,0 +1 @@
+Exercise class linker check for classes extending themselves (b/28685551).
diff --git a/test/804-class-extends-itself/smali/Main.smali b/test/804-class-extends-itself/smali/Main.smali
new file mode 100644
index 0000000000..5c349edcc9
--- /dev/null
+++ b/test/804-class-extends-itself/smali/Main.smali
@@ -0,0 +1,57 @@
+# Copyright (C) 2016 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# We cannot implement Main in Java, as this would require to run
+# dexmerger (to merge the Dex file produced from Smali code and the
+# Dex file produced from Java code), which loops indefinitely when
+# processing class B28685551, as this class inherits from itself.  As
+# a workaround, implement Main using Smali (we could also have used
+# multidex, but this requires a custom build script).
+
+.class public LMain;
+.super Ljava/lang/Object;
+
+.method public static main([Ljava/lang/String;)V
+    .registers 3
+    .param p0, "args"
+
+    invoke-static {}, LMain;->test()V
+    sget-object v0, Ljava/lang/System;->out:Ljava/io/PrintStream;
+    const-string v1, "Done!"
+    invoke-virtual {v0, v1}, Ljava/io/PrintStream;->println(Ljava/lang/String;)V
+    return-void
+.end method
+
+.method static test()V
+    .registers 4
+
+    :try_start
+    const-string v2, "B28685551"
+    invoke-static {v2}, Ljava/lang/Class;->forName(Ljava/lang/String;)Ljava/lang/Class;
+    :try_end
+    .catch Ljava/lang/ClassCircularityError; {:try_start .. :try_end} :catch
+
+    move-result-object v0
+
+    :goto_7
+    return-void
+
+    :catch
+    move-exception v1
+    .local v1, "e":Ljava/lang/ClassCircularityError;
+    sget-object v2, Ljava/lang/System;->out:Ljava/io/PrintStream;
+    const-string v3, "Caught ClassCircularityError"
+    invoke-virtual {v2, v3}, Ljava/io/PrintStream;->println(Ljava/lang/String;)V
+    goto :goto_7
+.end method
diff --git a/test/804-class-extends-itself/smali/b_28685551.smali b/test/804-class-extends-itself/smali/b_28685551.smali
new file mode 100644
index 0000000000..d98c6e3b32
--- /dev/null
+++ b/test/804-class-extends-itself/smali/b_28685551.smali
@@ -0,0 +1,18 @@
+# Copyright (C) 2016 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Regression test for a class inheriting from itself.
+
+.class public LB28685551;
+.super LB28685551;