/*

 * 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.

 *

 *

 */

#include <stdio.h>

#include <stdarg.h>

#include <stdlib.h>

#include <vector>

#include "sa.hpp"

#include "jni.h"

#include "jvmdi.h"

#ifndef WIN32

 #include <inttypes.h>

#else

 typedef int int32_t;

#endif

#ifdef WIN32

 #include <windows.h>

 #define YIELD() Sleep(0)

 #define SLEEP() Sleep(10)

 #define vsnprintf _vsnprintf

#else

 Error: please port YIELD() and SLEEP() macros to your platform

#endif

using namespace std;

//////////////////////////////////////////////////////////////////////

//                                                                  //

// Exported "interface" for Java language-level interaction between //

// the SA and the VM. Note that the SA knows about the layout of    //

// certain VM data structures and that knowledge is taken advantage //

// of in this code, although this interfaces with the VM via JVMDI. //

//                                                                  //

//////////////////////////////////////////////////////////////////////

extern "C" {

  /////////////////////////////////////

  //                                 //

  // Events sent by the VM to the SA //

  //                                 //

  /////////////////////////////////////

  // Set by the SA when it attaches. Indicates that events should be

  // posted via these exported variables, and that the VM should wait

  // for those events to be acknowledged by the SA (via its setting

  // saEventPending to 0).

  JNIEXPORT volatile int32_t saAttached     = 0;

  // Set to nonzero value by the VM when an event has been posted; set

  // back to 0 by the SA when it has processed that event.

  JNIEXPORT volatile int32_t saEventPending = 0;

  // Kind of the event (from jvmdi.h)

  JNIEXPORT volatile int32_t saEventKind    = 0;

  //

  // Exception events

  //

  JNIEXPORT jthread   saExceptionThread;

  JNIEXPORT jclass    saExceptionClass;

  JNIEXPORT jmethodID saExceptionMethod;

  JNIEXPORT int32_t   saExceptionLocation;

  JNIEXPORT jobject   saExceptionException;

  JNIEXPORT jclass    saExceptionCatchClass;

  JNIEXPORT jmethodID saExceptionCatchMethod;

  JNIEXPORT int32_t   saExceptionCatchLocation;

  //

  // Breakpoint events

  //

  JNIEXPORT jthread   saBreakpointThread;

  JNIEXPORT jclass    saBreakpointClass;

  JNIEXPORT jmethodID saBreakpointMethod;

  JNIEXPORT jlocation saBreakpointLocation;

  ///////////////////////////////////////

  //                                   //

  // Commands sent by the SA to the VM //

  //                                   //

  ///////////////////////////////////////

  extern JNIEXPORT const int32_t SA_CMD_SUSPEND_ALL       = 0;

  extern JNIEXPORT const int32_t SA_CMD_RESUME_ALL        = 1;

  extern JNIEXPORT const int32_t SA_CMD_TOGGLE_BREAKPOINT = 2;

  extern JNIEXPORT const int32_t SA_CMD_BUF_SIZE          = 1024;

  // SA sets this to a nonzero value when it is requesting a command

  // to be processed; VM sets it back to 0 when the command has been

  // executed

  JNIEXPORT volatile int32_t saCmdPending   = 0;

  // SA sets this to one of the manifest constants above to indicate

  // the kind of command to be executed

  JNIEXPORT volatile int32_t saCmdType      = 0;

  // VM sets this to 0 if the last command succeeded or a nonzero

  // value if it failed

  JNIEXPORT volatile int32_t saCmdResult    = 0;

  // If last command failed, this buffer will contain a descriptive

  // error message

  JNIEXPORT char             saCmdResultErrMsg[SA_CMD_BUF_SIZE];

  //

  // Toggling of breakpoint command arguments.

  //

  // Originally there were separate set/clear breakpoint commands

  // taking a class name, method name and signature, and the iteration

  // through the debug information was done in the SA. It turns out

  // that doing this work in the target VM is significantly faster,

  // and since interactivity when setting and clearing breakpoints is

  // important, the solution which resulted in more C/C++ code was used.

  //

  // Source file name

  JNIEXPORT char    saCmdBkptSrcFileName[SA_CMD_BUF_SIZE];

  // Package name ('/' as separator instead of '.')

  JNIEXPORT char    saCmdBkptPkgName[SA_CMD_BUF_SIZE];

  // Line number

  JNIEXPORT int32_t saCmdBkptLineNumber;

  // Output back to SA: indicator whether the last failure of a

  // breakpoint toggle command was really an error or just a lack of

  // debug information covering the requested line. 0 if not error.

  // Valid only if saCmdResult != 0.

  JNIEXPORT int32_t saCmdBkptResWasError;

  // Output back to SA: resulting line number at which the breakpoint

  // was set or cleared (valid only if saCmdResult == 0)

  JNIEXPORT int32_t saCmdBkptResLineNumber;

  // Output back to SA: resulting byte code index at which the

  // breakpoint was set or cleared (valid only if saCmdResult == 0)

  JNIEXPORT int32_t saCmdBkptResBCI;

  // Output back to SA: indicator whether the breakpoint operation

  // resulted in a set or cleared breakpoint; nonzero if set, zero if

  // cleared (valid only if saCmdResult == 0)

  JNIEXPORT int32_t saCmdBkptResWasSet;

  // Output back to SA: method name the breakpoint was set in (valid

  // only if saCmdResult == 0)

  JNIEXPORT char    saCmdBkptResMethodName[SA_CMD_BUF_SIZE];

  // Output back to SA: method signature (JNI style) the breakpoint

  // was set in (valid only if saCmdResult == 0)

  JNIEXPORT char    saCmdBkptResMethodSig[SA_CMD_BUF_SIZE];

}

// Internal state

static JavaVM* jvm = NULL;

static JVMDI_Interface_1* jvmdi = NULL;

static jthread debugThreadObj = NULL;

static bool suspended = false;

static vector<jthread> suspendedThreads;

static JVMDI_RawMonitor eventLock = NULL;

class MonitorLocker {

private:

  JVMDI_RawMonitor lock;

public:

  MonitorLocker(JVMDI_RawMonitor lock) {

    this->lock = lock;

    if (lock != NULL) {

      jvmdi->RawMonitorEnter(lock);

    }

  }

  ~MonitorLocker() {

    if (lock != NULL) {

      jvmdi->RawMonitorExit(lock);

    }

  }

};

class JvmdiDeallocator {

private:

  void* ptr;

public:

  JvmdiDeallocator(void* ptr) {

    this->ptr = ptr;

  }

  ~JvmdiDeallocator() {

    jvmdi->Deallocate((jbyte*) ptr);

  }

};

class JvmdiRefListDeallocator {

private:

  JNIEnv* env;

  jobject* refList;

  jint refCount;

public:

  JvmdiRefListDeallocator(JNIEnv* env, jobject* refList, jint refCount) {

    this->env = env;

    this->refList = refList;

    this->refCount = refCount;

  }

  ~JvmdiRefListDeallocator() {

    for (int i = 0; i < refCount; i++) {

      env->DeleteGlobalRef(refList[i]);

    }

    jvmdi->Deallocate((jbyte*) refList);

  }

};

static void

stop(char* msg) {

  fprintf(stderr, "%s", msg);

  fprintf(stderr, "\n");

  exit(1);

}

// This fills in the command result error message, sets the command

// result to -1, and clears the pending command flag

static void

reportErrorToSA(const char* str, ...) {

  va_list varargs;

  va_start(varargs, str);

  vsnprintf(saCmdResultErrMsg, sizeof(saCmdResultErrMsg), str, varargs);

  va_end(varargs);

  saCmdResult = -1;

  saCmdPending = 0;

}

static bool

packageNameMatches(char* clazzName, char* pkg) {

  int pkgLen = strlen(pkg);

  int clazzNameLen = strlen(clazzName);

  if (pkgLen >= clazzNameLen + 1) {

    return false;

  }

  if (strncmp(clazzName, pkg, pkgLen)) {

    return false;

  }

  // Ensure that '/' is the next character if non-empty package name

  int l = pkgLen;

  if (l > 0) {

    if (clazzName[l] != '/') {

      return false;

    }

    l++;

  }

  // Ensure that there are no more trailing slashes

  while (l < clazzNameLen) {

    if (clazzName[l++] == '/') {

      return false;

    }

  }

  return true;

}

static void

executeOneCommand(JNIEnv* env) {

  switch (saCmdType) {

  case SA_CMD_SUSPEND_ALL: {

    if (suspended) {

      reportErrorToSA("Target process already suspended");

      return;

    }

    // We implement this by getting all of the threads and calling

    // SuspendThread on each one, except for the thread object

    // corresponding to this thread. Each thread for which the call

    // succeeded (i.e., did not return JVMDI_ERROR_INVALID_THREAD)

    // is added to a list which is remembered for later resumption.

    // Note that this currently has race conditions since a thread

    // might be started after we call GetAllThreads and since a

    // thread for which we got an error earlier might be resumed by

    // the VM while we are busy suspending other threads. We could

    // solve this by looping until there are no more threads we can

    // suspend, but a more robust and scalable solution is to add

    // this functionality to the JVMDI interface (i.e.,

    // "suspendAll"). Probably need to provide an exclude list for

    // such a routine.

    jint threadCount;

    jthread* threads;

    if (jvmdi->GetAllThreads(&threadCount, &threads) != JVMDI_ERROR_NONE) {

      reportErrorToSA("Error while getting thread list");

      return;

    }

    for (int i = 0; i < threadCount; i++) {

      jthread thr = threads[i];

      if (!env->IsSameObject(thr, debugThreadObj)) {

        jvmdiError err = jvmdi->SuspendThread(thr);

        if (err == JVMDI_ERROR_NONE) {

          // Remember this thread and do not free it

          suspendedThreads.push_back(thr);

          continue;

        } else {

          fprintf(stderr, " SA: Error %d while suspending thread\n", err);

          // FIXME: stop, resume all threads, report error

        }

      }

      env->DeleteGlobalRef(thr);

    }

    // Free up threads

    jvmdi->Deallocate((jbyte*) threads);

    // Suspension is complete

    suspended = true;

    break;

  }

  case SA_CMD_RESUME_ALL: {

    if (!suspended) {

      reportErrorToSA("Target process already suspended");

      return;

    }

    saCmdResult = 0;

    bool errorOccurred = false;

    jvmdiError firstError;

    for (int i = 0; i < suspendedThreads.size(); i++) {

      jthread thr = suspendedThreads[i];

      jvmdiError err = jvmdi->ResumeThread(thr);

      env->DeleteGlobalRef(thr);

      if (err != JVMDI_ERROR_NONE) {

        if (!errorOccurred) {

          errorOccurred = true;

          firstError = err;

        }

      }

    }

    suspendedThreads.clear();

    suspended = false;

    if (errorOccurred) {

      reportErrorToSA("Error %d while resuming threads", firstError);

      return;

    }

    break;

  }

  case SA_CMD_TOGGLE_BREAKPOINT: {

    saCmdBkptResWasError = 1;

    // Search line number info for all loaded classes

    jint classCount;

    jclass* classes;

    jvmdiError glcRes = jvmdi->GetLoadedClasses(&classCount, &classes);

    if (glcRes != JVMDI_ERROR_NONE) {

      reportErrorToSA("Error %d while getting loaded classes", glcRes);

      return;

    }

    JvmdiRefListDeallocator rld(env, (jobject*) classes, classCount);

    bool done = false;

    bool gotOne = false;

    jclass targetClass;

    jmethodID targetMethod;

    jlocation targetLocation;

    jint targetLineNumber;

    for (int i = 0; i < classCount && !done; i++) {

      fflush(stderr);

      jclass clazz = classes[i];

      char* srcName;

      jvmdiError sfnRes = jvmdi->GetSourceFileName(clazz, &srcName);

      if (sfnRes == JVMDI_ERROR_NONE) {

        JvmdiDeallocator de1(srcName);

        if (!strcmp(srcName, saCmdBkptSrcFileName)) {

          // Got a match. Now see whether the package name of the class also matches

          char* clazzName;

          jvmdiError sigRes = jvmdi->GetClassSignature(clazz, &clazzName);

          if (sigRes != JVMDI_ERROR_NONE) {

            reportErrorToSA("Error %d while getting a class's signature", sigRes);

            return;

          }

          JvmdiDeallocator de2(clazzName);

          if (packageNameMatches(clazzName + 1, saCmdBkptPkgName)) {

            // Iterate through all methods

            jint methodCount;

            jmethodID* methods;

            if (jvmdi->GetClassMethods(clazz, &methodCount, &methods) != JVMDI_ERROR_NONE) {

              reportErrorToSA("Error while getting methods of class %s", clazzName);

              return;

            }

            JvmdiDeallocator de3(methods);

            for (int j = 0; j < methodCount && !done; j++) {

              jmethodID m = methods[j];

              jint entryCount;

              JVMDI_line_number_entry* table;

              jvmdiError lnRes = jvmdi->GetLineNumberTable(clazz, m, &entryCount, &table);

              if (lnRes == JVMDI_ERROR_NONE) {

                JvmdiDeallocator de4(table);

                // Look for line number greater than or equal to requested line

                for (int k = 0; k < entryCount && !done; k++) {

                  JVMDI_line_number_entry& entry = table[k];

                  if (entry.line_number >= saCmdBkptLineNumber &&

                      (!gotOne || entry.line_number < targetLineNumber)) {

                    gotOne = true;

                    targetClass = clazz;

                    targetMethod = m;

                    targetLocation = entry.start_location;

                    targetLineNumber = entry.line_number;

                    done = (targetLineNumber == saCmdBkptLineNumber);

                  }

                }

              } else if (lnRes != JVMDI_ERROR_ABSENT_INFORMATION) {

                reportErrorToSA("Unexpected error %d while fetching line number table", lnRes);

                return;

              }

            }

          }

        }

      } else if (sfnRes != JVMDI_ERROR_ABSENT_INFORMATION) {

        reportErrorToSA("Unexpected error %d while fetching source file name", sfnRes);

        return;

      }

    }

    bool wasSet = true;

    if (gotOne) {

      // Really toggle this breakpoint

      jvmdiError bpRes;

      bpRes = jvmdi->SetBreakpoint(targetClass, targetMethod, targetLocation);

      if (bpRes == JVMDI_ERROR_DUPLICATE) {

        bpRes = jvmdi->ClearBreakpoint(targetClass, targetMethod, targetLocation);

        wasSet = false;

      }

      if (bpRes != JVMDI_ERROR_NONE) {

        reportErrorToSA("Unexpected error %d while setting or clearing breakpoint at bci %d, line %d",

                        bpRes, targetLocation, targetLineNumber);

        return;

      }

    } else {

      saCmdBkptResWasError = 0;

      reportErrorToSA("No debug information found covering this line");

      return;

    }

    // Provide result

    saCmdBkptResLineNumber = targetLineNumber;

    saCmdBkptResBCI        = targetLocation;

    saCmdBkptResWasSet     = (wasSet ? 1 : 0);

    {

      char* methodName;

      char* methodSig;

      if (jvmdi->GetMethodName(targetClass, targetMethod, &methodName, &methodSig)

          == JVMDI_ERROR_NONE) {

        JvmdiDeallocator mnd(methodName);

        JvmdiDeallocator msd(methodSig);

        strncpy(saCmdBkptResMethodName, methodName, SA_CMD_BUF_SIZE);

        strncpy(saCmdBkptResMethodSig,  methodSig, SA_CMD_BUF_SIZE);

      } else {

        strncpy(saCmdBkptResMethodName, "<error>", SA_CMD_BUF_SIZE);

        strncpy(saCmdBkptResMethodSig,  "<error>", SA_CMD_BUF_SIZE);

      }

    }

    break;

  }

  default:

    reportErrorToSA("Command %d not yet supported", saCmdType);

    return;

  }

  // Successful command execution

  saCmdResult = 0;

  saCmdPending = 0;

}

static void

saCommandThread(void *arg) {

  JNIEnv* env = NULL;

  if (jvm->GetEnv((void **) &env, JNI_VERSION_1_2) != JNI_OK) {

    stop("Error while starting Serviceability Agent "

         "command thread: could not get JNI environment");

  }

  while (1) {

    // Wait for command

    while (!saCmdPending) {

      SLEEP();

    }

    executeOneCommand(env);

  }

}

static void

saEventHook(JNIEnv *env, JVMDI_Event *event)

{

  MonitorLocker ml(eventLock);

  saEventKind = event->kind;

  if (event->kind == JVMDI_EVENT_VM_INIT) {

    // Create event lock

    if (jvmdi->CreateRawMonitor("Serviceability Agent Event Lock", &eventLock)

        != JVMDI_ERROR_NONE) {

      stop("Unable to create Serviceability Agent's event lock");

    }

    // Start thread which receives commands from the SA.

    jclass threadClass = env->FindClass("java/lang/Thread");

    if (threadClass == NULL) stop("Unable to find class java/lang/Thread");

    jstring threadName = env->NewStringUTF("Serviceability Agent Command Thread");