ART: Add Field methods

Add GetFieldName, GetFieldDeclaringClass, GetFieldModifiers
and IsFieldSynthetic support. Add tests.

Bug: 34113943
Test: m test-art-host-run-test-918-fields
Change-Id: Id33b8c54c250f73f0658ec45ccb2b55eccb37623
diff --git a/runtime/openjdkjvmti/ti_field.cc b/runtime/openjdkjvmti/ti_field.cc
new file mode 100644
index 0000000..a762830
--- /dev/null
+++ b/runtime/openjdkjvmti/ti_field.cc
@@ -0,0 +1,171 @@
+/* Copyright (C) 2016 The Android Open Source Project
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This file implements interfaces from the file jvmti.h. This implementation
+ * is licensed under the same terms as the file jvmti.h.  The
+ * copyright and license information for the file jvmti.h follows.
+ *
+ * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "ti_field.h"
+
+#include "art_jvmti.h"
+#include "art_field-inl.h"
+#include "base/enums.h"
+#include "jni_internal.h"
+#include "modifiers.h"
+#include "scoped_thread_state_change-inl.h"
+#include "thread-inl.h"
+
+namespace openjdkjvmti {
+
+// Note: For all these functions, we could do a check that the field actually belongs to the given
+//       class. But the spec seems to assume a certain encoding of the field ID, and so doesn't
+//       specify any errors.
+
+jvmtiError FieldUtil::GetFieldName(jvmtiEnv* env,
+                                   jclass klass,
+                                   jfieldID field,
+                                   char** name_ptr,
+                                   char** signature_ptr,
+                                   char** generic_ptr) {
+  if (klass == nullptr) {
+    return ERR(INVALID_CLASS);
+  }
+  if (field == nullptr) {
+    return ERR(INVALID_FIELDID);
+  }
+
+  art::ScopedObjectAccess soa(art::Thread::Current());
+  art::ArtField* art_field = art::jni::DecodeArtField(field);
+
+  JvmtiUniquePtr name_copy;
+  if (name_ptr != nullptr) {
+    const char* field_name = art_field->GetName();
+    if (field_name == nullptr) {
+      field_name = "<error>";
+    }
+    unsigned char* tmp;
+    jvmtiError ret = CopyString(env, field_name, &tmp);
+    if (ret != ERR(NONE)) {
+      return ret;
+    }
+    name_copy = MakeJvmtiUniquePtr(env, tmp);
+    *name_ptr = reinterpret_cast<char*>(tmp);
+  }
+
+  JvmtiUniquePtr signature_copy;
+  if (signature_ptr != nullptr) {
+    const char* sig = art_field->GetTypeDescriptor();
+    unsigned char* tmp;
+    jvmtiError ret = CopyString(env, sig, &tmp);
+    if (ret != ERR(NONE)) {
+      return ret;
+    }
+    signature_copy = MakeJvmtiUniquePtr(env, tmp);
+    *signature_ptr = reinterpret_cast<char*>(tmp);
+  }
+
+  // TODO: Support generic signature.
+  if (generic_ptr != nullptr) {
+    *generic_ptr = nullptr;
+  }
+
+  // Everything is fine, release the buffers.
+  name_copy.release();
+  signature_copy.release();
+
+  return ERR(NONE);
+}
+
+jvmtiError FieldUtil::GetFieldDeclaringClass(jvmtiEnv* env ATTRIBUTE_UNUSED,
+                                             jclass klass,
+                                             jfieldID field,
+                                             jclass* declaring_class_ptr) {
+  if (klass == nullptr) {
+    return ERR(INVALID_CLASS);
+  }
+  if (field == nullptr) {
+    return ERR(INVALID_FIELDID);
+  }
+  if (declaring_class_ptr == nullptr) {
+    return ERR(NULL_POINTER);
+  }
+
+  art::ScopedObjectAccess soa(art::Thread::Current());
+  art::ArtField* art_field = art::jni::DecodeArtField(field);
+  art::ObjPtr<art::mirror::Class> field_klass = art_field->GetDeclaringClass();
+
+  *declaring_class_ptr = soa.AddLocalReference<jclass>(field_klass);
+
+  return ERR(NONE);
+}
+
+jvmtiError FieldUtil::GetFieldModifiers(jvmtiEnv* env ATTRIBUTE_UNUSED,
+                                        jclass klass,
+                                        jfieldID field,
+                                        jint* modifiers_ptr) {
+  if (klass == nullptr) {
+    return ERR(INVALID_CLASS);
+  }
+  if (field == nullptr) {
+    return ERR(INVALID_FIELDID);
+  }
+  if (modifiers_ptr == nullptr) {
+    return ERR(NULL_POINTER);
+  }
+
+  art::ScopedObjectAccess soa(art::Thread::Current());
+  art::ArtField* art_field = art::jni::DecodeArtField(field);
+  // Note: Keep this code in sync with Field.getModifiers.
+  uint32_t modifiers = art_field->GetAccessFlags() & 0xFFFF;
+
+  *modifiers_ptr = modifiers;
+  return ERR(NONE);
+}
+
+jvmtiError FieldUtil::IsFieldSynthetic(jvmtiEnv* env ATTRIBUTE_UNUSED,
+                                       jclass klass,
+                                       jfieldID field,
+                                       jboolean* is_synthetic_ptr) {
+  if (klass == nullptr) {
+    return ERR(INVALID_CLASS);
+  }
+  if (field == nullptr) {
+    return ERR(INVALID_FIELDID);
+  }
+  if (is_synthetic_ptr == nullptr) {
+    return ERR(NULL_POINTER);
+  }
+
+  art::ScopedObjectAccess soa(art::Thread::Current());
+  art::ArtField* art_field = art::jni::DecodeArtField(field);
+  uint32_t modifiers = art_field->GetAccessFlags();
+
+  *is_synthetic_ptr = ((modifiers & art::kAccSynthetic) != 0) ? JNI_TRUE : JNI_FALSE;
+  return ERR(NONE);
+}
+
+}  // namespace openjdkjvmti