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Java example source code file (sadis.c)

This example Java source code file (sadis.c) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

format_message_from_system, format_message_ignore_inserts, getlasterror, java_home\/jre\/lib\/sparc, java_sun_jvm_hotspot_asm_disassembler_decode, java_sun_jvm_hotspot_asm_disassembler_load_1library, jni_abort, jnicall, jnienv, jniexport, loadlibrary, null, rtld_global, rtld_lazy

The sadis.c Java example source code

/*
 * Copyright (c) 2012, 2013, 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 "sun_jvm_hotspot_asm_Disassembler.h"

/*
 *  This file implements a binding between Java and the hsdis
 *  dissasembler.  It should compile on Linux/Solaris and Windows.
 *  The only platform dependent pieces of the code for doing
 *  dlopen/dlsym to find the entry point in hsdis.  All the rest is
 *  standard JNI code.
 */

#ifdef _WINDOWS

#define snprintf  _snprintf
#define vsnprintf _vsnprintf

#include <windows.h>
#include <sys/types.h>
#include <sys/stat.h>
#ifdef _DEBUG
#include <crtdbg.h>
#endif

#else

#include <string.h>
#include <dlfcn.h>

#ifndef __APPLE__
#include <link.h>
#endif

#endif

#include <limits.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <errno.h>

#ifdef _WINDOWS
static int getLastErrorString(char *buf, size_t len)
{
    long errval;

    if ((errval = GetLastError()) != 0)
    {
      /* DOS error */
      size_t n = (size_t)FormatMessage(
            FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS,
            NULL,
            errval,
            0,
            buf,
            (DWORD)len,
            NULL);
      if (n > 3) {
        /* Drop final '.', CR, LF */
        if (buf[n - 1] == '\n') n--;
        if (buf[n - 1] == '\r') n--;
        if (buf[n - 1] == '.') n--;
        buf[n] = '\0';
      }
      return (int)n;
    }

    if (errno != 0)
    {
      /* C runtime error that has no corresponding DOS error code */
      const char *s = strerror(errno);
      size_t n = strlen(s);
      if (n >= len) n = len - 1;
      strncpy(buf, s, n);
      buf[n] = '\0';
      return (int)n;
    }
    return 0;
}
#endif /* _WINDOWS */

/*
 * Class:     sun_jvm_hotspot_asm_Disassembler
 * Method:    load_library
 * Signature: (Ljava/lang/String;)L
 */
JNIEXPORT jlong JNICALL Java_sun_jvm_hotspot_asm_Disassembler_load_1library(JNIEnv * env,
                                                                           jclass disclass,
                                                                           jstring jrepath_s,
                                                                           jstring libname_s) {
  uintptr_t func = 0;
  const char* error_message = NULL;
  jboolean isCopy;

  const char * jrepath = (*env)->GetStringUTFChars(env, jrepath_s, &isCopy); // like $JAVA_HOME/jre/lib/sparc/
  const char * libname = (*env)->GetStringUTFChars(env, libname_s, &isCopy);
  char buffer[128];

  /* Load the hsdis library */
#ifdef _WINDOWS
  HINSTANCE hsdis_handle;
  hsdis_handle = LoadLibrary(libname);
  if (hsdis_handle == NULL) {
    snprintf(buffer, sizeof(buffer), "%s%s", jrepath, libname);
    hsdis_handle = LoadLibrary(buffer);
  }
  if (hsdis_handle != NULL) {
    func = (uintptr_t)GetProcAddress(hsdis_handle, "decode_instructions_virtual");
  }
  if (func == 0) {
    getLastErrorString(buffer, sizeof(buffer));
    error_message = buffer;
  }
#else
  void* hsdis_handle;
  hsdis_handle = dlopen(libname, RTLD_LAZY | RTLD_GLOBAL);
  if (hsdis_handle == NULL) {
    snprintf(buffer, sizeof(buffer), "%s%s", jrepath, libname);
    hsdis_handle = dlopen(buffer, RTLD_LAZY | RTLD_GLOBAL);
  }
  if (hsdis_handle != NULL) {
    func = (uintptr_t)dlsym(hsdis_handle, "decode_instructions_virtual");
  }
  if (func == 0) {
    error_message = dlerror();
  }
#endif

  (*env)->ReleaseStringUTFChars(env, libname_s, libname);
  (*env)->ReleaseStringUTFChars(env, jrepath_s, jrepath);

  if (func == 0) {
    /* Couldn't find entry point.  error_message should contain some
     * platform dependent error message.
     */
    jclass eclass = (*env)->FindClass(env, "sun/jvm/hotspot/debugger/DebuggerException");
    (*env)->ThrowNew(env, eclass, error_message);
  }
  return (jlong)func;
}

/* signature of decode_instructions_virtual from hsdis.h */
typedef void* (*decode_func)(uintptr_t start_va, uintptr_t end_va,
                             unsigned char* start, uintptr_t length,
                             void* (*event_callback)(void*, const char*, void*),
                             void* event_stream,
                             int (*printf_callback)(void*, const char*, ...),
                             void* printf_stream,
                             const char* options,
                             int newline);

/* container for call back state when decoding instructions */
typedef struct {
  JNIEnv* env;
  jobject dis;
  jobject visitor;
  jmethodID handle_event;
  jmethodID raw_print;
  char buffer[4096];
} decode_env;


/* event callback binding to Disassembler.handleEvent */
static void* event_to_env(void* env_pv, const char* event, void* arg) {
  decode_env* denv = (decode_env*)env_pv;
  JNIEnv* env = denv->env;
  jstring event_string = (*env)->NewStringUTF(env, event);
  jlong result = (*env)->CallLongMethod(env, denv->dis, denv->handle_event, denv->visitor,
                                        event_string, (jlong) (uintptr_t)arg);
  if ((*env)->ExceptionOccurred(env) != NULL) {
    /* ignore exceptions for now */
    (*env)->ExceptionClear(env);
    result = 0;
  }
  return (void*)(uintptr_t)result;
}

/* printing callback binding to Disassembler.rawPrint */
static int printf_to_env(void* env_pv, const char* format, ...) {
  jstring output;
  va_list ap;
  int cnt;
  decode_env* denv = (decode_env*)env_pv;
  JNIEnv* env = denv->env;
  size_t flen = strlen(format);
  const char* raw = NULL;

  if (flen == 0)  return 0;
  if (flen < 2 ||
      strchr(format, '%') == NULL) {
    raw = format;
  } else if (format[0] == '%' && format[1] == '%' &&
             strchr(format+2, '%') == NULL) {
    // happens a lot on machines with names like %foo
    flen--;
    raw = format+1;
  }
  if (raw != NULL) {
    jstring output = (*env)->NewStringUTF(env, raw);
    (*env)->CallVoidMethod(env, denv->dis, denv->raw_print, denv->visitor, output);
    if ((*env)->ExceptionOccurred(env) != NULL) {
      /* ignore exceptions for now */
      (*env)->ExceptionClear(env);
    }
    return (int) flen;
  }
  va_start(ap, format);
  cnt = vsnprintf(denv->buffer, sizeof(denv->buffer), format, ap);
  va_end(ap);

  output = (*env)->NewStringUTF(env, denv->buffer);
  (*env)->CallVoidMethod(env, denv->dis, denv->raw_print, denv->visitor, output);
  if ((*env)->ExceptionOccurred(env) != NULL) {
    /* ignore exceptions for now */
    (*env)->ExceptionClear(env);
  }
  return cnt;
}

/*
 * Class:     sun_jvm_hotspot_asm_Disassembler
 * Method:    decode
 * Signature: (Lsun/jvm/hotspot/asm/InstructionVisitor;J[BLjava/lang/String;J)V
 */
JNIEXPORT void JNICALL Java_sun_jvm_hotspot_asm_Disassembler_decode(JNIEnv * env,
                                                                    jobject dis,
                                                                    jobject visitor,
                                                                    jlong startPc,
                                                                    jbyteArray code,
                                                                    jstring options_s,
                                                                    jlong decode_instructions_virtual) {
  jboolean isCopy;
  jbyte* start = (*env)->GetByteArrayElements(env, code, &isCopy);
  jbyte* end = start + (*env)->GetArrayLength(env, code);
  const char * options = (*env)->GetStringUTFChars(env, options_s, &isCopy);
  jclass disclass = (*env)->GetObjectClass(env, dis);

  decode_env denv;
  denv.env = env;
  denv.dis = dis;
  denv.visitor = visitor;

  /* find Disassembler.handleEvent callback */
  denv.handle_event = (*env)->GetMethodID(env, disclass, "handleEvent",
                                          "(Lsun/jvm/hotspot/asm/InstructionVisitor;Ljava/lang/String;J)J");
  if ((*env)->ExceptionOccurred(env)) {
    return;
  }

  /* find Disassembler.rawPrint callback */
  denv.raw_print = (*env)->GetMethodID(env, disclass, "rawPrint",
                                       "(Lsun/jvm/hotspot/asm/InstructionVisitor;Ljava/lang/String;)V");
  if ((*env)->ExceptionOccurred(env)) {
    return;
  }

  /* decode the buffer */
  (*(decode_func)(uintptr_t)decode_instructions_virtual)(startPc,
                                                         startPc + end - start,
                                                         (unsigned char*)start,
                                                         end - start,
                                                         &event_to_env,  (void*) &denv,
                                                         &printf_to_env, (void*) &denv,
                                                         options, 0 /* newline */);

  /* cleanup */
  (*env)->ReleaseByteArrayElements(env, code, start, JNI_ABORT);
  (*env)->ReleaseStringUTFChars(env, options_s, options);
}

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