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Java example source code file (hsdis-demo.c)

This example Java source code file (hsdis-demo.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

and, check_name, decode_instructions_name, decode_instructions_virtual_name, hello, hsdis_name, lib_ext, libarch, match, ns_demo, null, result, rtld_lazy, target_dir

The hsdis-demo.c Java example source code

/*
 * Copyright (c) 2008, 2012, 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.
 *
 */

/* hsdis-demo.c -- dump a range of addresses as native instructions
   This demonstrates the protocol required by the HotSpot PrintAssembly option.
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>

#include "hsdis.h"


void greet(const char*);
void disassemble(uintptr_t, uintptr_t);
void end_of_file();

const char* options = NULL;
int         raw     = 0;
int         xml     = 0;

int main(int ac, char** av) {
  int greeted = 0;
  int i;
  for (i = 1; i < ac; i++) {
    const char* arg = av[i];
    if (arg[0] == '-') {
      if (!strcmp(arg, "-xml"))
        xml ^= 1;
      else if (!strcmp(arg, "-raw"))
        raw ^= 1;
      else if (!strncmp(arg, "-options=", 9))
        options = arg+9;
      else
        { printf("Usage: %s [-xml] [name...]\n", av[0]); exit(2); }
      continue;
    }
    greet(arg);
    greeted = 1;
  }
  if (!greeted)
    greet("world");
  printf("...And now for something completely different:\n");
  void *start = (void*) &main;
  void *end = (void*) &end_of_file;
#if defined(__ia64) || defined(__powerpc__)
  /* On IA64 and PPC function pointers are pointers to function descriptors */
  start = *((void**)start);
  end = *((void**)end);
#endif
  disassemble(start, (end > start) ? end : start + 64);
  printf("Cheers!\n");
}

void greet(const char* whom) {
  printf("Hello, %s!\n", whom);
}

void end_of_file() { }

/* don't disassemble after this point... */

#include "dlfcn.h"

#define DECODE_INSTRUCTIONS_VIRTUAL_NAME "decode_instructions_virtual"
#define DECODE_INSTRUCTIONS_NAME "decode_instructions"
#define HSDIS_NAME               "hsdis"
static void* decode_instructions_pv = 0;
static void* decode_instructions_sv = 0;
static const char* hsdis_path[] = {
  HSDIS_NAME"-"LIBARCH LIB_EXT,
  "./" HSDIS_NAME"-"LIBARCH LIB_EXT,
#ifdef TARGET_DIR
  TARGET_DIR"/"HSDIS_NAME"-"LIBARCH LIB_EXT,
#endif
  NULL
};

static const char* load_decode_instructions() {
  void* dllib = NULL;
  const char* *next_in_path = hsdis_path;
  while (1) {
    decode_instructions_pv = dlsym(dllib, DECODE_INSTRUCTIONS_VIRTUAL_NAME);
    decode_instructions_sv = dlsym(dllib, DECODE_INSTRUCTIONS_NAME);
    if (decode_instructions_pv != NULL || decode_instructions_sv != NULL)
      return NULL;
    if (dllib != NULL)
      return "plugin does not defined "DECODE_INSTRUCTIONS_VIRTUAL_NAME" and "DECODE_INSTRUCTIONS_NAME;
    for (dllib = NULL; dllib == NULL; ) {
      const char* next_lib = (*next_in_path++);
      if (next_lib == NULL)
        return "cannot find plugin "HSDIS_NAME LIB_EXT;
      dllib = dlopen(next_lib, RTLD_LAZY);
    }
  }
}


static const char* lookup(void* addr) {
#if defined(__ia64) || defined(__powerpc__)
  /* On IA64 and PPC function pointers are pointers to function descriptors */
#define CHECK_NAME(fn) \
  if (addr == *((void**) &fn))  return #fn;
#else
#define CHECK_NAME(fn) \
  if (addr == (void*) &fn)  return #fn;
#endif

  CHECK_NAME(main);
  CHECK_NAME(greet);
  return NULL;
}

/* does the event match the tag, followed by a null, space, or slash? */
#define MATCH(event, tag) \
  (!strncmp(event, tag, sizeof(tag)-1) && \
   (!event[sizeof(tag)-1] || strchr(" /", event[sizeof(tag)-1])))


static const char event_cookie[] = "event_cookie"; /* demo placeholder */
static void* simple_handle_event(void* cookie, const char* event, void* arg) {
  if (MATCH(event, "/insn")) {
    // follow each complete insn by a nice newline
    printf("\n");
  }
  return NULL;
}

static void* handle_event(void* cookie, const char* event, void* arg) {
#define NS_DEMO "demo:"
  if (cookie != event_cookie)
    printf("*** bad event cookie %p != %p\n", cookie, event_cookie);

  if (xml) {
    /* We could almost do a printf(event, arg),
       but for the sake of a better demo,
       we dress the result up as valid XML.
    */
    const char* fmt = strchr(event, ' ');
    int evlen = (fmt ? fmt - event : strlen(event));
    if (!fmt) {
      if (event[0] != '/') {
        printf("<"NS_DEMO"%.*s>", evlen, event);
      } else {
        printf("</"NS_DEMO"%.*s>", evlen-1, event+1);
      }
    } else {
      if (event[0] != '/') {
        printf("<"NS_DEMO"%.*s", evlen, event);
        printf(fmt, arg);
        printf(">");
      } else {
        printf("<"NS_DEMO"%.*s_done", evlen-1, event+1);
        printf(fmt, arg);
        printf("/></"NS_DEMO"%.*s>", evlen-1, event+1);
      }
    }
  }

  if (MATCH(event, "insn")) {
    const char* name = lookup(arg);
    if (name)  printf("%s:\n", name);

    /* basic action for <insn>: */
    printf(" %p\t", arg);

  } else if (MATCH(event, "/insn")) {
    // follow each complete insn by a nice newline
    printf("\n");
  } else if (MATCH(event, "mach")) {
    printf("Decoding for CPU '%s'\n", (char*) arg);

  } else if (MATCH(event, "addr")) {
    /* basic action for <addr/>: */
    const char* name = lookup(arg);
    if (name) {
      printf("&%s (%p)", name, arg);
      /* return non-null to notify hsdis not to print the addr */
      return arg;
    }
  }

  /* null return is always safe; can mean "I ignored it" */
  return NULL;
}

#define fprintf_callback \
  (decode_instructions_printf_callback_ftype)&fprintf

void disassemble(uintptr_t from, uintptr_t to) {
  const char* err = load_decode_instructions();
  if (err != NULL) {
    printf("%s: %s\n", err, dlerror());
    exit(1);
  }
  decode_func_vtype decode_instructions_v
    = (decode_func_vtype) decode_instructions_pv;
  decode_func_stype decode_instructions_s
    = (decode_func_stype) decode_instructions_sv;
  void* res;
  if (decode_instructions_pv != NULL) {
    printf("\nDecoding from %p to %p...with %s\n", from, to, DECODE_INSTRUCTIONS_VIRTUAL_NAME);
    if (raw) {
      res = (*decode_instructions_v)(from, to,
                                     (unsigned char*)from, to - from,
                                     simple_handle_event, stdout,
                                     NULL, stdout,
                                     options, 0);
    } else {
      res = (*decode_instructions_v)(from, to,
                                    (unsigned char*)from, to - from,
                                     handle_event, (void*) event_cookie,
                                     fprintf_callback, stdout,
                                     options, 0);
    }
    if (res != (void*)to)
      printf("*** Result was %p!\n", res);
  }
  void* sres;
  if (decode_instructions_sv != NULL) {
    printf("\nDecoding from %p to %p...with old decode_instructions\n", from, to, DECODE_INSTRUCTIONS_NAME);
    if (raw) {
      sres = (*decode_instructions_s)(from, to,
                                      simple_handle_event, stdout,
                                      NULL, stdout,
                                      options);
    } else {
      sres = (*decode_instructions_s)(from, to,
                                      handle_event, (void*) event_cookie,
                                      fprintf_callback, stdout,
                                      options);
    }
    if (sres != (void *)to)
      printf("*** Result of decode_instructions %p!\n", sres);
  }
}

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