runtime/native/OpenjdkJvm.cc

/*
 * Copyright (C) 2014 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.
 */

/*
 * Services that OpenJDK expects the VM to provide.
 */
#include<stdio.h>
#include <dlfcn.h>
#include <limits.h>
#include <unistd.h>

#include "common_throws.h"
#include "gc/heap.h"
#include "thread.h"
#include "thread_list.h"
#include "runtime.h"
#include "handle_scope-inl.h"
#include "scoped_thread_state_change.h"
#include "ScopedUtfChars.h"
#include "mirror/class_loader.h"
#include "verify_object-inl.h"
#include "base/logging.h"
#include "base/macros.h"
#include "../../libcore/ojluni/src/main/native/jvm.h" // TODO(haaawk): fix it
#include "jni_internal.h"
#include "mirror/string-inl.h"
#include "scoped_fast_native_object_access.h"
#include "ScopedLocalRef.h"
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/ioctl.h>

#undef LOG_TAG
#define LOG_TAG "artopenjdx"

/* posix open() with extensions; used by e.g. ZipFile */
JNIEXPORT jint JVM_Open(const char* fname, jint flags, jint mode)
{
    LOG(DEBUG) << "JVM_Open fname='" << fname << "', flags=" << flags << ", mode=" << mode;

    /*
     * The call is expected to handle JVM_O_DELETE, which causes the file
     * to be removed after it is opened.  Also, some code seems to
     * want the special return value JVM_EEXIST if the file open fails
     * due to O_EXCL.
     */
    int fd = TEMP_FAILURE_RETRY(open(fname, flags & ~JVM_O_DELETE, mode));
    if (fd < 0) {
        int err = errno;
        LOG(DEBUG) << "open(" << fname << ") failed: " << strerror(errno);
        if (err == EEXIST) {
            return JVM_EEXIST;
        } else {
            return -1;
        }
    }

    if (flags & JVM_O_DELETE) {
        LOG(DEBUG) << "Deleting '" << fname << "' after open\n";
        if (unlink(fname) != 0) {
            LOG(WARNING) << "Post-open deletion of '" << fname << "' failed: " << strerror(errno);
        }
        /* ignore */
    }

    LOG(VERBOSE) << "open(" << fname << ") --> " << fd;
    return fd;
}

/* posix close() */
JNIEXPORT jint JVM_Close(jint fd)
{
    LOG(DEBUG) << "JVM_Close fd=" << fd;
    // don't want TEMP_FAILURE_RETRY here -- file is closed even if EINTR
    return close(fd);
}

/* posix read() */
JNIEXPORT jint JVM_Read(jint fd, char* buf, jint nbytes)
{
    LOG(DEBUG) << "JVM_Read fd=" << fd << ", buf='" << buf << "', nbytes=" << nbytes;
    return TEMP_FAILURE_RETRY(read(fd, buf, nbytes));
}

/* posix write(); is used to write messages to stderr */
JNIEXPORT jint JVM_Write(jint fd, char* buf, jint nbytes)
{
    LOG(DEBUG) << "JVM_Write fd=" << fd << ", buf='" << buf << "', nbytes=" << nbytes;
    return TEMP_FAILURE_RETRY(write(fd, buf, nbytes));
}

/* posix lseek() */
JNIEXPORT jlong JVM_Lseek(jint fd, jlong offset, jint whence)
{
    LOG(DEBUG) << "JVM_Lseek fd=" << fd << ", offset=" << offset << ", whence=" << whence;
    return TEMP_FAILURE_RETRY(lseek(fd, offset, whence));
}
/*
 * "raw monitors" seem to be expected to behave like non-recursive pthread
 * mutexes.  They're used by ZipFile.
 */

JNIEXPORT void* JVM_RawMonitorCreate(void)
{
    LOG(DEBUG) << "JVM_RawMonitorCreate";
    pthread_mutex_t* newMutex =
        (pthread_mutex_t*) malloc(sizeof(pthread_mutex_t));
    pthread_mutex_init(newMutex, NULL);
    return newMutex;
}

JNIEXPORT void JVM_RawMonitorDestroy(void* mon)
{
    LOG(DEBUG) << "JVM_RawMonitorDestroy mon=" << mon;
    pthread_mutex_destroy((pthread_mutex_t*) mon);
}

JNIEXPORT jint JVM_RawMonitorEnter(void* mon)
{
    LOG(DEBUG) << "JVM_RawMonitorEnter mon=" << mon;
    return pthread_mutex_lock((pthread_mutex_t*) mon);
}

JNIEXPORT void JVM_RawMonitorExit(void* mon)
{
    LOG(DEBUG) << "JVM_RawMonitorExit mon=" << mon;
    pthread_mutex_unlock((pthread_mutex_t*) mon);
}

JNIEXPORT char* JVM_NativePath(char* path)
{
    LOG(DEBUG) << "JVM_NativePath path='" << path << "'";
    return path;
}

JNIEXPORT jint JVM_GetLastErrorString(char* buf, int len)
{
    int err = errno;    // grab before JVM_TRACE can trash it
    LOG(DEBUG) << "JVM_GetLastErrorString buf=" << buf << ", len=" << len;

#ifdef __GLIBC__
    if (len == 0)
        return 0;

    char* result = strerror_r(err, buf, len);
    if (result != buf) {
        strncpy(buf, result, len);
        buf[len-1] = '\0';
    }
    return strlen(buf);
#else
    return strerror_r(err, buf, len);
#endif
}

JNIEXPORT int jio_fprintf(FILE* fp, const char* fmt, ...)
{
    va_list args;

    va_start(args, fmt);
    int len = jio_vfprintf(fp, fmt, args);
    va_end(args);

    return len;
}

JNIEXPORT int jio_vfprintf(FILE* fp, const char* fmt, va_list args)
{
    assert(fp != NULL);
    return vfprintf(fp, fmt, args);
}

/* posix fsync() */
JNIEXPORT jint JVM_Sync(jint fd)
{
    LOG(DEBUG) << "JVM_Sync fd=" << fd;
    return TEMP_FAILURE_RETRY(fsync(fd));
}

JNIEXPORT void* JVM_FindLibraryEntry(void* handle, const char* name)
{
    LOG(DEBUG) << "JVM_FindLibraryEntry handle=" << handle << " name=" << name;
    return dlsym(handle, name);
}

JNIEXPORT jlong JVM_CurrentTimeMillis(JNIEnv* env, jclass unused)
{
    LOG(DEBUG) << "JVM_CurrentTimeMillis env=" << env;
    struct timeval tv;

    gettimeofday(&tv, (struct timezone *) NULL);
    jlong when = tv.tv_sec * 1000LL + tv.tv_usec / 1000;
    return when;
}

JNIEXPORT jint JVM_Socket(jint domain, jint type, jint protocol)
{
    LOG(DEBUG) << "JVM_Socket domain=" << domain << ", type=" << type << ", protocol=" << protocol;

    return TEMP_FAILURE_RETRY(socket(domain, type, protocol));
}

JNIEXPORT jint JVM_InitializeSocketLibrary() {
  return 0;
}

int jio_vsnprintf(char *str, size_t count, const char *fmt, va_list args) {
   if ((intptr_t)count <= 0) return -1;
   return vsnprintf(str, count, fmt, args);
}

int jio_snprintf(char *str, size_t count, const char *fmt, ...) {
   va_list args;
   int len;
   va_start(args, fmt);
   len = jio_vsnprintf(str, count, fmt, args);
   va_end(args);
   return len;
}

JNIEXPORT jint JVM_SetSockOpt(jint fd, int level, int optname,
    const char* optval, int optlen)
{
    LOG(DEBUG) << "JVM_SetSockOpt fd=" << fd << ", level=" << level << ", optname=" << optname
               << ", optval=" << optval << ", optlen=" << optlen;
    return TEMP_FAILURE_RETRY(setsockopt(fd, level, optname, optval, optlen));
}

JNIEXPORT jint JVM_SocketShutdown(jint fd, jint howto)
{
    LOG(DEBUG) << "JVM_SocketShutdown fd=" << fd << ", howto=" << howto;
    return TEMP_FAILURE_RETRY(shutdown(fd, howto));
}

JNIEXPORT jint JVM_GetSockOpt(jint fd, int level, int optname, char* optval,
    int* optlen)
{
    LOG(DEBUG) << "JVM_GetSockOpt fd=" << fd << ", level=" << level << ", optname=" << optname
               << ", optval=" << optval << ", optlen=" << optlen;

    socklen_t len = *optlen;
    int cc = TEMP_FAILURE_RETRY(getsockopt(fd, level, optname, optval, &len));
    *optlen = len;
    return cc;
}

JNIEXPORT jint JVM_GetSockName(jint fd, struct sockaddr* addr, int* addrlen)
{
    LOG(DEBUG) << "JVM_GetSockName fd=" << fd << ", addr=" << addr << ", addrlen=" << addrlen;

    socklen_t len = *addrlen;
    int cc = TEMP_FAILURE_RETRY(getsockname(fd, addr, &len));
    *addrlen = len;
    return cc;
}

JNIEXPORT jint JVM_SocketAvailable(jint fd, jint* result)
{
    LOG(DEBUG) << "JVM_SocketAvailable fd=" << fd << ", result=" << result;

    if (TEMP_FAILURE_RETRY(ioctl(fd, FIONREAD, result)) < 0) {
        LOG(DEBUG) << "ioctl(" << fd << ", FIONREAD) failed: " << strerror(errno);
        return JNI_FALSE;
    }

    return JNI_TRUE;
}

JNIEXPORT jint JVM_Send(jint fd, char* buf, jint nBytes, jint flags)
{
    LOG(DEBUG) << "JVM_Send fd=" << fd << ", buf=" << buf << ", nBytes=" << nBytes << ", flags="
               << flags;

    return TEMP_FAILURE_RETRY(send(fd, buf, nBytes, flags));
}

JNIEXPORT jint JVM_SocketClose(jint fd)
{
    LOG(DEBUG) << "JVM_SocketClose fd=" << fd;

    // don't want TEMP_FAILURE_RETRY here -- file is closed even if EINTR
    return close(fd);
}

JNIEXPORT jint JVM_Listen(jint fd, jint count)
{
    LOG(DEBUG) << "JVM_Listen fd=" << fd << ", count=" << count;

    return TEMP_FAILURE_RETRY(listen(fd, count));
}

JNIEXPORT jint JVM_Connect(jint fd, struct sockaddr* addr, jint addrlen)
{
    LOG(DEBUG) << "JVM_Connect fd=" << fd << ", addr=" << addr << ", addrlen=" << addrlen;

    return TEMP_FAILURE_RETRY(connect(fd, addr, addrlen));
}

JNIEXPORT int JVM_GetHostName(char* name, int namelen)
{
    LOG(DEBUG) << "JVM_GetHostName name=" << name << ", namelen=" << namelen;

    return TEMP_FAILURE_RETRY(gethostname(name, namelen));
}

JNIEXPORT jstring JVM_InternString(JNIEnv* env, jstring jstr)
{
    LOG(DEBUG) << "JVM_InternString env=" << env << ", jstr=" << jstr;
    art::ScopedFastNativeObjectAccess soa(env);
    art::mirror::String* s = soa.Decode<art::mirror::String*>(jstr);
    art::mirror::String* result = s->Intern();
    return soa.AddLocalReference<jstring>(result);
}

JNIEXPORT jlong JVM_FreeMemory(void) {
    return art::Runtime::Current()->GetHeap()->GetFreeMemory();
}

JNIEXPORT jlong JVM_TotalMemory(void) {
    return art::Runtime::Current()->GetHeap()->GetTotalMemory();
}

JNIEXPORT jlong JVM_MaxMemory(void) {
    return art::Runtime::Current()->GetHeap()->GetMaxMemory();
}

JNIEXPORT void JVM_GC(void) {
    if (art::Runtime::Current()->IsExplicitGcDisabled()) {
        LOG(INFO) << "Explicit GC skipped.";
        return;
    }
    art::Runtime::Current()->GetHeap()->CollectGarbage(false);
}

JNIEXPORT void JVM_Exit(jint status) {
  LOG(INFO) << "System.exit called, status: " << status;
  art::Runtime::Current()->CallExitHook(status);
  exit(status);
}

JNIEXPORT jstring JVM_NativeLoad(JNIEnv* env, jstring javaFilename, jobject javaLoader,
                                 jstring javaLdLibraryPath) {
  ScopedUtfChars filename(env, javaFilename);
  if (filename.c_str() == NULL) {
    return NULL;
  }

  if (javaLdLibraryPath != NULL) {
    ScopedUtfChars ldLibraryPath(env, javaLdLibraryPath);
    if (ldLibraryPath.c_str() == NULL) {
      return NULL;
    }
    void* sym = dlsym(RTLD_DEFAULT, "android_update_LD_LIBRARY_PATH");
    if (sym != NULL) {
      typedef void (*Fn)(const char*);
      Fn android_update_LD_LIBRARY_PATH = reinterpret_cast<Fn>(sym);
      (*android_update_LD_LIBRARY_PATH)(ldLibraryPath.c_str());
    } else {
      LOG(ERROR) << "android_update_LD_LIBRARY_PATH not found; .so dependencies will not work!";
    }
  }

  std::string detail;
  {
    art::ScopedObjectAccess soa(env);
    art::StackHandleScope<1> hs(soa.Self());
    art::Handle<art::mirror::ClassLoader> classLoader(
        hs.NewHandle(soa.Decode<art::mirror::ClassLoader*>(javaLoader)));
    art::JavaVMExt* vm = art::Runtime::Current()->GetJavaVM();
    bool success = vm->LoadNativeLibrary(filename.c_str(), classLoader, &detail);
    if (success) {
      return nullptr;
    }
  }

  // Don't let a pending exception from JNI_OnLoad cause a CheckJNI issue with NewStringUTF.
  env->ExceptionClear();
  return env->NewStringUTF(detail.c_str());
}

JNIEXPORT void JVM_StartThread(JNIEnv* env, jobject jthread, jlong stack_size, jboolean daemon) {
  art::Thread::CreateNativeThread(env, jthread, stack_size, daemon == JNI_TRUE);
}

JNIEXPORT void JVM_SetThreadPriority(JNIEnv* env, jobject jthread, jint prio) {
  art::ScopedObjectAccess soa(env);
  art::MutexLock mu(soa.Self(), *art::Locks::thread_list_lock_);
  art::Thread* thread = art::Thread::FromManagedThread(soa, jthread);
  if (thread != NULL) {
    thread->SetNativePriority(prio);
  }
}

JNIEXPORT void JVM_Yield(JNIEnv* env, jclass threadClass) {
  sched_yield();
}

JNIEXPORT void JVM_Sleep(JNIEnv* env, jclass threadClass, jobject java_lock, jlong millis) {
  art::ScopedFastNativeObjectAccess soa(env);
  art::mirror::Object* lock = soa.Decode<art::mirror::Object*>(java_lock);
  art::Monitor::Wait(art::Thread::Current(), lock, millis, 0, true, art::kSleeping);
}

JNIEXPORT jobject JVM_CurrentThread(JNIEnv* env, jclass unused) {
  art::ScopedFastNativeObjectAccess soa(env);
  return soa.AddLocalReference<jobject>(soa.Self()->GetPeer());
}

JNIEXPORT void JVM_Interrupt(JNIEnv* env, jobject jthread) {
  art::ScopedFastNativeObjectAccess soa(env);
  art::MutexLock mu(soa.Self(), *art::Locks::thread_list_lock_);
  art::Thread* thread = art::Thread::FromManagedThread(soa, jthread);
  if (thread != nullptr) {
    thread->Interrupt(soa.Self());
  }
}

JNIEXPORT jboolean JVM_IsInterrupted(JNIEnv* env, jobject jthread, jboolean clearInterrupted) {
  if (clearInterrupted) {
    return static_cast<art::JNIEnvExt*>(env)->self->Interrupted() ? JNI_TRUE : JNI_FALSE;
  } else {
    art::ScopedFastNativeObjectAccess soa(env);
    art::MutexLock mu(soa.Self(), *art::Locks::thread_list_lock_);
    art::Thread* thread = art::Thread::FromManagedThread(soa, jthread);
    return (thread != nullptr) ? thread->IsInterrupted() : JNI_FALSE;
  }
}

JNIEXPORT jboolean JVM_HoldsLock(JNIEnv* env, jclass unused, jobject jobj) {
  art::ScopedObjectAccess soa(env);
  art::mirror::Object* object = soa.Decode<art::mirror::Object*>(jobj);
  if (object == NULL) {
    art::ThrowNullPointerException(NULL, "object == null");
    return JNI_FALSE;
  }
  return soa.Self()->HoldsLock(object);
}

JNIEXPORT void JVM_SetNativeThreadName(JNIEnv* env, jobject jthread, jstring java_name) {
  ScopedUtfChars name(env, java_name);
  art::Thread* self;
  {
    art::ScopedObjectAccess soa(env);
    if (soa.Decode<art::mirror::Object*>(jthread) == soa.Self()->GetPeer()) {
      soa.Self()->SetThreadName(name.c_str());
      return;
    }
    self = soa.Self();
  }
  // Suspend thread to avoid it from killing itself while we set its name. We don't just hold the
  // thread list lock to avoid this, as setting the thread name causes mutator to lock/unlock
  // in the DDMS send code.
  art::ThreadList* thread_list = art::Runtime::Current()->GetThreadList();
  bool timed_out;
  // Take suspend thread lock to avoid races with threads trying to suspend this one.
  art::Thread* thread;
  {
    art::MutexLock mu(self, *art::Locks::thread_list_suspend_thread_lock_);
    thread = thread_list->SuspendThreadByPeer(jthread, true, false, &timed_out);
  }
  if (thread != NULL) {
    {
      art::ScopedObjectAccess soa(env);
      thread->SetThreadName(name.c_str());
    }
    thread_list->Resume(thread, false);
  } else if (timed_out) {
    LOG(ERROR) << "Trying to set thread name to '" << name.c_str() << "' failed as the thread "
        "failed to suspend within a generous timeout.";
  }
}

JNIEXPORT jint JVM_IHashCode(JNIEnv* env, jobject javaObject) {
  if (UNLIKELY(javaObject == nullptr)) {
    return 0;
  }
  art::ScopedFastNativeObjectAccess soa(env);
  art::mirror::Object* o = soa.Decode<art::mirror::Object*>(javaObject);
  return static_cast<jint>(o->IdentityHashCode());
}

JNIEXPORT jlong JVM_NanoTime(JNIEnv* env, jclass unused) {
#if defined(HAVE_POSIX_CLOCKS)
    timespec now;
    clock_gettime(CLOCK_MONOTONIC, &now);
    return now.tv_sec * 1000000000LL + now.tv_nsec;
#else
    timeval now;
    gettimeofday(&now, NULL);
    return static_cast<jlong>(now.tv_sec) * 1000000000LL + now.tv_usec * 1000LL;
#endif
}
static void ThrowArrayStoreException_NotAnArray(const char* identifier, art::mirror::Object* array)
    SHARED_LOCKS_REQUIRED(art::Locks::mutator_lock_) {
  std::string actualType(art::PrettyTypeOf(array));
  art::Thread* self = art::Thread::Current();
  art::ThrowLocation throw_location = self->GetCurrentLocationForThrow();
  self->ThrowNewExceptionF(throw_location, "Ljava/lang/ArrayStoreException;",
                           "%s of type %s is not an array", identifier, actualType.c_str());
}

JNIEXPORT void JVM_ArrayCopy(JNIEnv* env, jclass unused, jobject javaSrc,
                             jint srcPos, jobject javaDst, jint dstPos, jint length) {
  // The API is defined in terms of length, but length is somewhat overloaded so we use count.
  const jint count = length;
  art::ScopedFastNativeObjectAccess soa(env);

  // Null pointer checks.
  if (UNLIKELY(javaSrc == nullptr)) {
    art::ThrowNullPointerException(nullptr, "src == null");
    return;
  }
  if (UNLIKELY(javaDst == nullptr)) {
    art::ThrowNullPointerException(nullptr, "dst == null");
    return;
  }

  // Make sure source and destination are both arrays.
  art::mirror::Object* srcObject = soa.Decode<art::mirror::Object*>(javaSrc);
  if (UNLIKELY(!srcObject->IsArrayInstance())) {
    ThrowArrayStoreException_NotAnArray("source", srcObject);
    return;
  }
  art::mirror::Object* dstObject = soa.Decode<art::mirror::Object*>(javaDst);
  if (UNLIKELY(!dstObject->IsArrayInstance())) {
    ThrowArrayStoreException_NotAnArray("destination", dstObject);
    return;
  }
  art::mirror::Array* srcArray = srcObject->AsArray();
  art::mirror::Array* dstArray = dstObject->AsArray();

  // Bounds checking.
  if (UNLIKELY(srcPos < 0) || UNLIKELY(dstPos < 0) || UNLIKELY(count < 0) ||
      UNLIKELY(srcPos > srcArray->GetLength() - count) ||
      UNLIKELY(dstPos > dstArray->GetLength() - count)) {
    art::ThrowLocation throw_location = soa.Self()->GetCurrentLocationForThrow();
    soa.Self()->ThrowNewExceptionF(throw_location, "Ljava/lang/ArrayIndexOutOfBoundsException;",
                                   "src.length=%d srcPos=%d dst.length=%d dstPos=%d length=%d",
                                   srcArray->GetLength(), srcPos, dstArray->GetLength(), dstPos,
                                   count);
    return;
  }

  art::mirror::Class* dstComponentType = dstArray->GetClass()->GetComponentType();
  art::mirror::Class* srcComponentType = srcArray->GetClass()->GetComponentType();
  art::Primitive::Type dstComponentPrimitiveType = dstComponentType->GetPrimitiveType();

  if (LIKELY(srcComponentType == dstComponentType)) {
    // Trivial assignability.
    switch (dstComponentPrimitiveType) {
      case art::Primitive::kPrimVoid:
        LOG(FATAL) << "Unreachable, cannot have arrays of type void";
        return;
      case art::Primitive::kPrimBoolean:
      case art::Primitive::kPrimByte:
        DCHECK_EQ(art::Primitive::ComponentSize(dstComponentPrimitiveType), 1U);
        dstArray->AsByteSizedArray()->Memmove(dstPos, srcArray->AsByteSizedArray(), srcPos, count);
        return;
      case art::Primitive::kPrimChar:
      case art::Primitive::kPrimShort:
        DCHECK_EQ(art::Primitive::ComponentSize(dstComponentPrimitiveType), 2U);
        dstArray->AsShortSizedArray()->Memmove(dstPos, srcArray->AsShortSizedArray(), srcPos, count);
        return;
      case art::Primitive::kPrimInt:
      case art::Primitive::kPrimFloat:
        DCHECK_EQ(art::Primitive::ComponentSize(dstComponentPrimitiveType), 4U);
        dstArray->AsIntArray()->Memmove(dstPos, srcArray->AsIntArray(), srcPos, count);
        return;
      case art::Primitive::kPrimLong:
      case art::Primitive::kPrimDouble:
        DCHECK_EQ(art::Primitive::ComponentSize(dstComponentPrimitiveType), 8U);
        dstArray->AsLongArray()->Memmove(dstPos, srcArray->AsLongArray(), srcPos, count);
        return;
      case art::Primitive::kPrimNot: {
        art::mirror::ObjectArray<art::mirror::Object>* dstObjArray = dstArray->AsObjectArray<art::mirror::Object>();
        art::mirror::ObjectArray<art::mirror::Object>* srcObjArray = srcArray->AsObjectArray<art::mirror::Object>();
        dstObjArray->AssignableMemmove(dstPos, srcObjArray, srcPos, count);
        return;
      }
      default:
        LOG(FATAL) << "Unknown array type: " << art::PrettyTypeOf(srcArray);
        return;
    }
  }
  // If one of the arrays holds a primitive type the other array must hold the exact same type.
  if (UNLIKELY((dstComponentPrimitiveType != art::Primitive::kPrimNot) ||
               srcComponentType->IsPrimitive())) {
    std::string srcType(art::PrettyTypeOf(srcArray));
    std::string dstType(art::PrettyTypeOf(dstArray));
    art::ThrowLocation throw_location = soa.Self()->GetCurrentLocationForThrow();
    soa.Self()->ThrowNewExceptionF(throw_location, "Ljava/lang/ArrayStoreException;",
                                   "Incompatible types: src=%s, dst=%s",
                                   srcType.c_str(), dstType.c_str());
    return;
  }
  // Arrays hold distinct types and so therefore can't alias - use memcpy instead of memmove.
  art::mirror::ObjectArray<art::mirror::Object>* dstObjArray = dstArray->AsObjectArray<art::mirror::Object>();
  art::mirror::ObjectArray<art::mirror::Object>* srcObjArray = srcArray->AsObjectArray<art::mirror::Object>();
  // If we're assigning into say Object[] then we don't need per element checks.
  if (dstComponentType->IsAssignableFrom(srcComponentType)) {
    dstObjArray->AssignableMemcpy(dstPos, srcObjArray, srcPos, count);
    return;
  }
  dstObjArray->AssignableCheckingMemcpy(dstPos, srcObjArray, srcPos, count, true);
}

JNIEXPORT jint JVM_FindSignal(const char* name) {
  static const char* names[] = {
        "", "HUP", "INT", "QUIT",
        "ILL", "TRAP", "ABRT", "BUS",
        "FPE", "KILL", "USR1", "SEGV",
        "USR2", "PIPE", "ALRM", "TERM",
        NULL
    };

    int i = 0;
    while (names[++i] != NULL) {
        if (strcmp(name, names[i]) == 0) {
            return i;
        }
    }
    LOG(WARNING) << "Signal '" << name << "' not found";
    assert(false);
    return 0;
}

/* signal handler */
static void internalSignalHandler(int sig)
{
    /*
     * This is expected to invoke sun.misc.Signal.dispatch().  We really
     * don't want to do that directly from a signal handler, so if we
     * decide we need this we should hook it into the safe-point mechanism.
     */
}

JNIEXPORT void* JVM_RegisterSignal(jint signum, void* handler)
{
    LOG(INFO) << "SIGNAL: signum=" << signum << ", handler=" << handler;

    struct sigaction act, oldact;

    /* OpenJDK code makes these assumptions */
    assert(SIG_DFL == (void*)0);
    assert(SIG_IGN == (void*)1);

    if (handler == (void*) 2) {
        /* magic value indicating we should use our internal handler */
        handler = (void*) internalSignalHandler;
    }

    act.sa_handler = (void (*)(int))handler;
    sigemptyset(&act.sa_mask);
    act.sa_flags = SA_RESTART;
    sigaction(signum, &act, &oldact);

    if (oldact.sa_handler == internalSignalHandler) {
        return (void*) 2;
    } else {
        return (void*) oldact.sa_handler;
    }
}

JNIEXPORT jboolean JVM_RaiseSignal(jint signum)
{
    raise(signum);
    return JNI_TRUE;
}

JNIEXPORT void JVM_Halt(jint code) {
  exit(code);
}