/*

 * Copyright (c) 2005, 2018, 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.

 *

 * 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 "precompiled.hpp"

#include "classfile/javaClasses.hpp"

#include "classfile/systemDictionary.hpp"

#include "gc/shared/vmGCOperations.hpp"

#include "memory/resourceArea.hpp"

#include "oops/oop.inline.hpp"

#include "oops/typeArrayOop.inline.hpp"

#include "prims/jvmtiExport.hpp"

#include "runtime/arguments.hpp"

#include "runtime/globals.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/java.hpp"

#include "runtime/javaCalls.hpp"

#include "runtime/os.hpp"

#include "services/attachListener.hpp"

#include "services/diagnosticCommand.hpp"

#include "services/heapDumper.hpp"

#include "services/writeableFlags.hpp"

#include "utilities/debug.hpp"

#include "utilities/formatBuffer.hpp"

volatile bool AttachListener::_initialized;

// Implementation of "properties" command.

//

// Invokes VMSupport.serializePropertiesToByteArray to serialize

// the system properties into a byte array.

static InstanceKlass* load_and_initialize_klass(Symbol* sh, TRAPS) {

  Klass* k = SystemDictionary::resolve_or_fail(sh, true, CHECK_NULL);

  InstanceKlass* ik = InstanceKlass::cast(k);

  if (ik->should_be_initialized()) {

    ik->initialize(CHECK_NULL);

  }

  return ik;

}

static jint get_properties(AttachOperation* op, outputStream* out, Symbol* serializePropertiesMethod) {

  Thread* THREAD = Thread::current();

  HandleMark hm;

  // load VMSupport

  Symbol* klass = vmSymbols::jdk_internal_vm_VMSupport();

  InstanceKlass* k = load_and_initialize_klass(klass, THREAD);

  if (HAS_PENDING_EXCEPTION) {

    java_lang_Throwable::print(PENDING_EXCEPTION, out);

    CLEAR_PENDING_EXCEPTION;

    return JNI_ERR;

  }

  // invoke the serializePropertiesToByteArray method

  JavaValue result(T_OBJECT);

  JavaCallArguments args;

  Symbol* signature = vmSymbols::serializePropertiesToByteArray_signature();

  JavaCalls::call_static(&result,

                         k,

                         serializePropertiesMethod,

                         signature,

                         &args,

                         THREAD);

  if (HAS_PENDING_EXCEPTION) {

    java_lang_Throwable::print(PENDING_EXCEPTION, out);

    CLEAR_PENDING_EXCEPTION;

    return JNI_ERR;

  }

  // The result should be a [B

  oop res = (oop)result.get_jobject();

  assert(res->is_typeArray(), "just checking");

  assert(TypeArrayKlass::cast(res->klass())->element_type() == T_BYTE, "just checking");

  // copy the bytes to the output stream

  typeArrayOop ba = typeArrayOop(res);

  jbyte* addr = typeArrayOop(res)->byte_at_addr(0);

  out->print_raw((const char*)addr, ba->length());

  return JNI_OK;

}

// Implementation of "load" command.

static jint load_agent(AttachOperation* op, outputStream* out) {

  // get agent name and options

  const char* agent = op->arg(0);

  const char* absParam = op->arg(1);

  const char* options = op->arg(2);

  // If loading a java agent then need to ensure that the java.instrument module is loaded

  if (strcmp(agent, "instrument") == 0) {

    Thread* THREAD = Thread::current();

    ResourceMark rm(THREAD);

    HandleMark hm(THREAD);

    JavaValue result(T_OBJECT);

    Handle h_module_name = java_lang_String::create_from_str("java.instrument", THREAD);

    JavaCalls::call_static(&result,

                           SystemDictionary::module_Modules_klass(),

                           vmSymbols::loadModule_name(),

                           vmSymbols::loadModule_signature(),

                           h_module_name,

                           THREAD);

    if (HAS_PENDING_EXCEPTION) {

      java_lang_Throwable::print(PENDING_EXCEPTION, out);

      CLEAR_PENDING_EXCEPTION;

      return JNI_ERR;

    }

  }

  return JvmtiExport::load_agent_library(agent, absParam, options, out);

}

// Implementation of "properties" command.

// See also: PrintSystemPropertiesDCmd class

static jint get_system_properties(AttachOperation* op, outputStream* out) {

  return get_properties(op, out, vmSymbols::serializePropertiesToByteArray_name());

}

// Implementation of "agent_properties" command.

static jint get_agent_properties(AttachOperation* op, outputStream* out) {

  return get_properties(op, out, vmSymbols::serializeAgentPropertiesToByteArray_name());

}

// Implementation of "datadump" command.

//

// Raises a SIGBREAK signal so that VM dump threads, does deadlock detection,

// etc. In theory this command should only post a DataDumpRequest to any

// JVMTI environment that has enabled this event. However it's useful to

// trigger the SIGBREAK handler.

static jint data_dump(AttachOperation* op, outputStream* out) {

  if (!ReduceSignalUsage) {

    AttachListener::pd_data_dump();

  } else {

    if (JvmtiExport::should_post_data_dump()) {

      JvmtiExport::post_data_dump();

    }

  }

  return JNI_OK;

}

// Implementation of "threaddump" command - essentially a remote ctrl-break

// See also: ThreadDumpDCmd class

//

static jint thread_dump(AttachOperation* op, outputStream* out) {

  bool print_concurrent_locks = false;

  if (op->arg(0) != NULL && strcmp(op->arg(0), "-l") == 0) {

    print_concurrent_locks = true;

  }

  // thread stacks

  VM_PrintThreads op1(out, print_concurrent_locks);

  VMThread::execute(&op1);

  // JNI global handles

  VM_PrintJNI op2(out);

  VMThread::execute(&op2);

  // Deadlock detection

  VM_FindDeadlocks op3(out);

  VMThread::execute(&op3);

  return JNI_OK;

}

// A jcmd attach operation request was received, which will now

// dispatch to the diagnostic commands used for serviceability functions.

static jint jcmd(AttachOperation* op, outputStream* out) {

  Thread* THREAD = Thread::current();

  // All the supplied jcmd arguments are stored as a single

  // string (op->arg(0)). This is parsed by the Dcmd framework.

  DCmd::parse_and_execute(DCmd_Source_AttachAPI, out, op->arg(0), ' ', THREAD);

  if (HAS_PENDING_EXCEPTION) {

    java_lang_Throwable::print(PENDING_EXCEPTION, out);

    out->cr();

    CLEAR_PENDING_EXCEPTION;

    return JNI_ERR;

  }

  return JNI_OK;

}

// Implementation of "dumpheap" command.

// See also: HeapDumpDCmd class

//

// Input arguments :-

//   arg0: Name of the dump file

//   arg1: "-live" or "-all"

jint dump_heap(AttachOperation* op, outputStream* out) {

  const char* path = op->arg(0);

  if (path == NULL || path[0] == '\0') {

    out->print_cr("No dump file specified");

  } else {

    bool live_objects_only = true;   // default is true to retain the behavior before this change is made

    const char* arg1 = op->arg(1);

    if (arg1 != NULL && (strlen(arg1) > 0)) {

      if (strcmp(arg1, "-all") != 0 && strcmp(arg1, "-live") != 0) {

        out->print_cr("Invalid argument to dumpheap operation: %s", arg1);

        return JNI_ERR;

      }

      live_objects_only = strcmp(arg1, "-live") == 0;

    }

    // Request a full GC before heap dump if live_objects_only = true

    // This helps reduces the amount of unreachable objects in the dump

    // and makes it easier to browse.

    HeapDumper dumper(live_objects_only /* request GC */);

    int res = dumper.dump(op->arg(0));

    if (res == 0) {

      out->print_cr("Heap dump file created");

    } else {

      // heap dump failed

      ResourceMark rm;

      char* error = dumper.error_as_C_string();

      if (error == NULL) {

        out->print_cr("Dump failed - reason unknown");

      } else {

        out->print_cr("%s", error);

      }

    }

  }

  return JNI_OK;

}

// Implementation of "inspectheap" command

// See also: ClassHistogramDCmd class

//

// Input arguments :-

//   arg0: "-live" or "-all"

static jint heap_inspection(AttachOperation* op, outputStream* out) {

  bool live_objects_only = true;   // default is true to retain the behavior before this change is made

  const char* arg0 = op->arg(0);

  if (arg0 != NULL && (strlen(arg0) > 0)) {

    if (strcmp(arg0, "-all") != 0 && strcmp(arg0, "-live") != 0) {

      out->print_cr("Invalid argument to inspectheap operation: %s", arg0);

      return JNI_ERR;

    }

    live_objects_only = strcmp(arg0, "-live") == 0;

  }

  VM_GC_HeapInspection heapop(out, live_objects_only /* request full gc */);

  VMThread::execute(&heapop);

  return JNI_OK;

}

// Implementation of "setflag" command

static jint set_flag(AttachOperation* op, outputStream* out) {

  const char* name = NULL;

  if ((name = op->arg(0)) == NULL) {

    out->print_cr("flag name is missing");

    return JNI_ERR;

  }

  FormatBuffer<80> err_msg("%s", "");

      // if the flag is not manageable try to change it through

      // the platform dependent implementation

      return AttachListener::pd_set_flag(op, out);

    } else {

      out->print_cr("%s", err_msg.buffer());

    }

    return JNI_ERR;

  }

  return JNI_OK;

}

// Implementation of "printflag" command

// See also: PrintVMFlagsDCmd class

static jint print_flag(AttachOperation* op, outputStream* out) {

  const char* name = NULL;

  if ((name = op->arg(0)) == NULL) {

    out->print_cr("flag name is missing");

    return JNI_ERR;

  }

  if (f) {

    f->print_as_flag(out);

    out->cr();

  } else {

    out->print_cr("no such flag '%s'", name);

  }

  return JNI_OK;

}

// Table to map operation names to functions.

// names must be of length <= AttachOperation::name_length_max

static AttachOperationFunctionInfo funcs[] = {

  { "agentProperties",  get_agent_properties },

  { "datadump",         data_dump },

  { "dumpheap",         dump_heap },

  { "load",             load_agent },

  { "properties",       get_system_properties },

  { "threaddump",       thread_dump },

  { "inspectheap",      heap_inspection },

  { "setflag",          set_flag },

  { "printflag",        print_flag },

  { "jcmd",             jcmd },

  { NULL,               NULL }

};

// The Attach Listener threads services a queue. It dequeues an operation

// from the queue, examines the operation name (command), and dispatches

// to the corresponding function to perform the operation.

static void attach_listener_thread_entry(JavaThread* thread, TRAPS) {

  os::set_priority(thread, NearMaxPriority);

  assert(thread == Thread::current(), "Must be");

  assert(thread->stack_base() != NULL && thread->stack_size() > 0,

         "Should already be setup");

  if (AttachListener::pd_init() != 0) {

    return;

  }

  AttachListener::set_initialized();

  for (;;) {

    AttachOperation* op = AttachListener::dequeue();

    if (op == NULL) {

      return;   // dequeue failed or shutdown

    }

    ResourceMark rm;

    bufferedStream st;

    jint res = JNI_OK;

    // handle special detachall operation

    if (strcmp(op->name(), AttachOperation::detachall_operation_name()) == 0) {

      AttachListener::detachall();

    } else if (!EnableDynamicAgentLoading && strcmp(op->name(), "load") == 0) {

      st.print("Dynamic agent loading is not enabled. "

               "Use -XX:+EnableDynamicAgentLoading to launch target VM.");

      res = JNI_ERR;

    } else {

      // find the function to dispatch too

      AttachOperationFunctionInfo* info = NULL;

      for (int i=0; funcs[i].name != NULL; i++) {

        const char* name = funcs[i].name;

        assert(strlen(name) <= AttachOperation::name_length_max, "operation <= name_length_max");

        if (strcmp(op->name(), name) == 0) {

          info = &(funcs[i]);

          break;

        }

      }

      // check for platform dependent attach operation

      if (info == NULL) {

        info = AttachListener::pd_find_operation(op->name());

      }

      if (info != NULL) {

        // dispatch to the function that implements this operation

        res = (info->func)(op, &st);

      } else {

        st.print("Operation %s not recognized!", op->name());

        res = JNI_ERR;

      }

    }

    // operation complete - send result and output to client

    op->complete(res, &st);

  }

}

bool AttachListener::has_init_error(TRAPS) {

  if (HAS_PENDING_EXCEPTION) {

    tty->print_cr("Exception in VM (AttachListener::init) : ");

    java_lang_Throwable::print(PENDING_EXCEPTION, tty);

    tty->cr();

    CLEAR_PENDING_EXCEPTION;

    return true;

  } else {

    return false;

  }

}

// Starts the Attach Listener thread

void AttachListener::init() {

  EXCEPTION_MARK;

  Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, THREAD);

  if (has_init_error(THREAD)) {

    return;

  }

  InstanceKlass* klass = InstanceKlass::cast(k);

  instanceHandle thread_oop = klass->allocate_instance_handle(THREAD);

  if (has_init_error(THREAD)) {

    return;

  }

  const char thread_name[] = "Attach Listener";

  Handle string = java_lang_String::create_from_str(thread_name, THREAD);

  if (has_init_error(THREAD)) {

    return;

  }

  // Initialize thread_oop to put it into the system threadGroup

  Handle thread_group (THREAD, Universe::system_thread_group());

  JavaValue result(T_VOID);

  JavaCalls::call_special(&result, thread_oop,

                       klass,

                       vmSymbols::object_initializer_name(),

                       vmSymbols::threadgroup_string_void_signature(),

                       thread_group,

                       string,

                       THREAD);

  if (has_init_error(THREAD)) {

    return;

  }

  Klass* group = SystemDictionary::ThreadGroup_klass();

  JavaCalls::call_special(&result,

                        thread_group,

                        group,

                        vmSymbols::add_method_name(),

                        vmSymbols::thread_void_signature(),

                        thread_oop,             // ARG 1

                        THREAD);

  if (has_init_error(THREAD)) {

    return;

  }

  { MutexLocker mu(Threads_lock);

    JavaThread* listener_thread = new JavaThread(&attach_listener_thread_entry);

    // Check that thread and osthread were created

    if (listener_thread == NULL || listener_thread->osthread() == NULL) {

      vm_exit_during_initialization("java.lang.OutOfMemoryError",

                                    os::native_thread_creation_failed_msg());

    }

    java_lang_Thread::set_thread(thread_oop(), listener_thread);

    java_lang_Thread::set_daemon(thread_oop());

    listener_thread->set_threadObj(thread_oop());

    Threads::add(listener_thread);

    Thread::start(listener_thread);

  }

}

// Performs clean-up tasks on platforms where we can detect that the last

// client has detached

void AttachListener::detachall() {

  // call the platform dependent clean-up

  pd_detachall();

}