Start adding implementations for runtime-provided native methods.

The library can't do everything...

Change-Id: Ib808c00570c7214aeb2ca058b1a66cacbeb372f1

1 files changed, 259 insertions, 0 deletions

diff --git a/src/java_lang_System.cc b/src/java_lang_System.cc
new file mode 100644
index 0000000000..e874987a1e
--- /dev/null
+++ b/src/java_lang_System.cc
@@ -0,0 +1,259 @@
+/*
+ * Copyright (C) 2008 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.
+ */
+
+#include "jni_internal.h"
+#include "object.h"
+
+#include "JniConstants.h" // Last to avoid problems with LOG redefinition.
+
+/*
+ * We make guarantees about the atomicity of accesses to primitive
+ * variables.  These guarantees also apply to elements of arrays.
+ * In particular, 8-bit, 16-bit, and 32-bit accesses must be atomic and
+ * must not cause "word tearing".  Accesses to 64-bit array elements must
+ * either be atomic or treated as two 32-bit operations.  References are
+ * always read and written atomically, regardless of the number of bits
+ * used to represent them.
+ *
+ * We can't rely on standard libc functions like memcpy(3) and memmove(3)
+ * in our implementation of System.arraycopy, because they may copy
+ * byte-by-byte (either for the full run or for "unaligned" parts at the
+ * start or end).  We need to use functions that guarantee 16-bit or 32-bit
+ * atomicity as appropriate.
+ *
+ * System.arraycopy() is heavily used, so having an efficient implementation
+ * is important.  The bionic libc provides a platform-optimized memory move
+ * function that should be used when possible.  If it's not available,
+ * the trivial "reference implementation" versions below can be used until
+ * a proper version can be written.
+ *
+ * For these functions, The caller must guarantee that dst/src are aligned
+ * appropriately for the element type, and that n is a multiple of the
+ * element size.
+ */
+#ifdef __BIONIC__
+#define HAVE_MEMMOVE_WORDS
+#endif
+
+#ifdef HAVE_MEMMOVE_WORDS
+extern "C" void _memmove_words(void* dst, const void* src, size_t n);
+#define move16 _memmove_words
+#define move32 _memmove_words
+#else
+static void move16(void* dst, const void* src, size_t n) {
+  DCHECK((((uintptr_t) dst | (uintptr_t) src | n) & 0x01) == 0);
+
+  uint16_t* d = reinterpret_cast<uint16_t*>(dst);
+  const uint16_t* s = reinterpret_cast<const uint16_t*>(src);
+
+  n /= sizeof(uint16_t);
+
+  if (d < s) {
+    // Copy forwards.
+    while (n--) {
+      *d++ = *s++;
+    }
+  } else {
+    // Copy backwards.
+    d += n;
+    s += n;
+    while (n--) {
+      *--d = *--s;
+    }
+  }
+}
+
+static void move32(void* dst, const void* src, size_t n) {
+  DCHECK((((uintptr_t) dst | (uintptr_t) src | n) & 0x03) == 0);
+
+  uint32_t* d = reinterpret_cast<uint32_t*>(dst);
+  const uint32_t* s = reinterpret_cast<const uint32_t*>(src);
+
+  n /= sizeof(uint32_t);
+
+  if (d < s) {
+    // Copy forwards.
+    while (n--) {
+      *d++ = *s++;
+    }
+  } else {
+    // Copy backwards.
+    d += n;
+    s += n;
+    while (n--) {
+      *--d = *--s;
+    }
+  }
+}
+#endif // HAVE_MEMMOVE_WORDS
+
+namespace art {
+
+namespace {
+
+void ThrowArrayStoreException_NotAnArray(const char* identifier, Object* array) {
+  std::string actualType(PrettyType(array));
+  Thread::Current()->ThrowNewException("Ljava/lang/ArrayStoreException;", "%s is not an array: %s", identifier, actualType.c_str());
+}
+
+void System_arraycopy(JNIEnv* env, jclass, jobject javaSrc, jint srcPos, jobject javaDst, jint dstPos, jint length) {
+  Thread* self = Thread::Current();
+
+  // Null pointer checks.
+  if (javaSrc == NULL) {
+    self->ThrowNewException("Ljava/lang/NullPointerException;", "src == null");
+    return;
+  }
+  if (javaDst == NULL) {
+    self->ThrowNewException("Ljava/lang/NullPointerException;", "dst == null");
+    return;
+  }
+
+  // Make sure source and destination are both arrays.
+  Object* srcObject = Decode<Object*>(env, javaSrc);
+  Object* dstObject = Decode<Object*>(env, javaDst);
+  if (!srcObject->IsArrayInstance()) {
+    ThrowArrayStoreException_NotAnArray("src", srcObject);
+    return;
+  }
+  if (!dstObject->IsArrayInstance()) {
+    ThrowArrayStoreException_NotAnArray("dst", dstObject);
+    return;
+  }
+  Array* srcArray = srcObject->AsArray();
+  Array* dstArray = dstObject->AsArray();
+  Class* srcComponentType = srcArray->GetClass()->GetComponentType();
+  Class* dstComponentType = dstArray->GetClass()->GetComponentType();
+
+  // Bounds checking.
+  if (srcPos < 0 || dstPos < 0 || length < 0 || srcPos > srcArray->GetLength() - length || dstPos > dstArray->GetLength() - length) {
+    self->ThrowNewException("Ljava/lang/ArrayIndexOutOfBoundsException;",
+        "src.length=%d srcPos=%d dst.length=%d dstPos=%d length=%d",
+        srcArray->GetLength(), srcPos, dstArray->GetLength(), dstPos, length);
+    return;
+  }
+
+  uint8_t* dstBytes = reinterpret_cast<uint8_t*>(dstArray->GetRawData());
+  const uint8_t* srcBytes = reinterpret_cast<const uint8_t*>(srcArray->GetRawData());
+
+  // Handle primitive arrays.
+  if (srcComponentType->IsPrimitive() || dstComponentType->IsPrimitive()) {
+    // If one of the arrays holds a primitive type the other array must hold the exact same type.
+    if (srcComponentType->IsPrimitive() != dstComponentType->IsPrimitive() || srcComponentType != dstComponentType) {
+      std::string srcType(PrettyType(srcArray));
+      std::string dstType(PrettyType(dstArray));
+      self->ThrowNewException("Ljava/lang/ArrayStoreException;",
+          "Incompatible types: src=%s, dst=%s", srcType.c_str(), dstType.c_str());
+      return;
+    }
+
+    switch (srcArray->GetClass()->GetComponentSize()) {
+    case 1:
+      memmove(dstBytes + dstPos, srcBytes + srcPos, length);
+      break;
+    case 2:
+      move16(dstBytes + dstPos * 2, srcBytes + srcPos * 2, length * 2);
+      break;
+    case 4:
+      move32(dstBytes + dstPos * 4, srcBytes + srcPos * 4, length * 4);
+      break;
+    case 8:
+      // We don't need to guarantee atomicity of the entire 64-bit word.
+      move32(dstBytes + dstPos * 8, srcBytes + srcPos * 8, length * 8);
+      break;
+    default:
+      LOG(FATAL) << "Unknown primitive array type: " << PrettyType(srcArray);
+    }
+
+    return;
+  }
+
+  // Neither class is primitive. Are the types trivially compatible?
+  const int width = sizeof(Object*);
+  bool sameDimensions = srcArray->GetClass()->array_rank_ == dstArray->GetClass()->array_rank_;
+  if (sameDimensions && srcComponentType->InstanceOf(dstComponentType)) {
+    // Yes. Bulk copy.
+    move32(dstBytes + dstPos * width, srcBytes + srcPos * width, length * width);
+    UNIMPLEMENTED(WARNING) << "write barriers in System.arraycopy";
+    //dvmWriteBarrierArray(dstArray, dstPos, dstPos + length);
+    return;
+  }
+
+  // The arrays are not trivially compatible.  However, we
+  // may still be able to do this if the destination object is
+  // compatible (e.g. copy Object[] to String[], but the Object
+  // being copied is actually a String).  We need to copy elements
+  // one by one until something goes wrong.
+  //
+  // Because of overlapping moves, what we really want to do
+  // is compare the types and count up how many we can move,
+  // then call move32() to shift the actual data.  If we just
+  // start from the front we could do a smear rather than a move.
+
+  // TODO: this idea is flawed. a malicious caller could exploit the check-use
+  // race by modifying the source array after we check but before we copy,
+  // and cause us to copy incompatible elements.
+
+  Object** srcObj = reinterpret_cast<ObjectArray<Object>*>(srcArray)->GetData() + srcPos;
+  Class* dstClass = dstArray->GetClass();
+
+  Class* initialElementClass = NULL;
+  if (length > 0 && srcObj[0] != NULL) {
+    initialElementClass = srcObj[0]->GetClass();
+    if (!Class::CanPutArrayElementNoThrow(initialElementClass, dstClass)) {
+      initialElementClass = NULL;
+    }
+  }
+
+  int copyCount;
+  for (copyCount = 0; copyCount < length; copyCount++) {
+    if (srcObj[copyCount] != NULL && srcObj[copyCount]->GetClass() != initialElementClass && !Class::CanPutArrayElementNoThrow(srcObj[copyCount]->GetClass(), dstClass)) {
+      // Can't put this element into the array.
+      // We'll copy up to this point, then throw.
+      break;
+    }
+  }
+
+  move32(dstBytes + dstPos * width, srcBytes + srcPos * width, copyCount * width);
+  UNIMPLEMENTED(WARNING) << "write barriers in System.arraycopy";
+  //dvmWriteBarrierArray(dstArray, 0, copyCount);
+  if (copyCount != length) {
+    std::string actualSrcType(PrettyType(srcObj[copyCount]));
+    std::string dstType(PrettyType(dstArray));
+    self->ThrowNewException("Ljava/lang/ArrayStoreException;",
+        "source[%d] of type %s cannot be stored in destination array of type %s",
+        srcPos + copyCount, actualSrcType.c_str(), dstType.c_str());
+    return;
+  }
+}
+
+jint System_identityHashCode(JNIEnv* env, jclass, jobject javaObject) {
+  Object* o = Decode<Object*>(env, javaObject);
+  return static_cast<jint>(reinterpret_cast<uintptr_t>(o));
+}
+
+JNINativeMethod gMethods[] = {
+  NATIVE_METHOD(System, arraycopy, "(Ljava/lang/Object;ILjava/lang/Object;II)V"),
+  NATIVE_METHOD(System, identityHashCode, "(Ljava/lang/Object;)I"),
+};
+
+}  // namespace
+
+void register_java_lang_System(JNIEnv* env) {
+    jniRegisterNativeMethods(env, "java/lang/System", gMethods, NELEM(gMethods));
+}
+
+}  // namespace art