/*

 * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 *   - Redistributions of source code must retain the above copyright

 *     notice, this list of conditions and the following disclaimer.

 *

 *   - Redistributions in binary form must reproduce the above copyright

 *     notice, this list of conditions and the following disclaimer in the

 *     documentation and/or other materials provided with the distribution.

 *

 *   - Neither the name of Oracle nor the names of its

 *     contributors may be used to endorse or promote products derived

 *     from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/*

 * This source code is provided to illustrate the usage of a given feature

 * or technique and has been deliberately simplified. Additional steps

 * required for a production-quality application, such as security checks,

 * input validation and proper error handling, might not be present in

 * this sample code.

 */

/* Class reader writer (java_crw_demo) for instrumenting bytecodes */

/*

 * As long as the callbacks allow for it and the class number is unique,

 *     this code is completely re-entrant and any number of classfile

 *     injections can happen at the same time.

 *

 *     The current logic requires a unique number for this class instance

 *     or (jclass,jobject loader) pair, this is done via the ClassIndex

 *     in hprof, which is passed in as the 'unsigned cnum' to java_crw_demo().

 *     It's up to the user of this interface if it wants to use this

 *     feature.

 *

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

/* Get Java and class file and bytecode information. */

#include <jni.h>

#include "classfile_constants.h"

/* Include our own interface for cross check */

#include "java_crw_demo.h"

/* Macros over error functions to capture line numbers */

/* Fatal error used in all builds. */

/* Use THIS_FILE when it is available. */

#ifndef THIS_FILE

    #define THIS_FILE "java_crw.demo.c" /* Never use __FILE__ */

#endif

#define CRW_FATAL(ci, message) fatal_error(ci, message, THIS_FILE, __LINE__)

#if defined(DEBUG) || !defined(NDEBUG)

  /* This assert macro is only used in the debug builds. */

  #define CRW_ASSERT(ci, cond) \

        ((cond)?(void)0:assert_error(ci, #cond, THIS_FILE, __LINE__))

#else

  #define CRW_ASSERT(ci, cond)

#endif

#define CRW_ASSERT_MI(mi) CRW_ASSERT((mi)?(mi)->ci:NULL,(mi)!=NULL)

#define CRW_ASSERT_CI(ci) CRW_ASSERT(ci, ( (ci) != NULL && \

                         (ci)->input_position <= (ci)->input_len && \

                         (ci)->output_position <= (ci)->output_len) )

#define BUFSIZE 256

#ifdef _WIN32

#define snprintf(buffer, count, format, ...) _snprintf_s(buffer, count, _TRUNCATE, format, ##__VA_ARGS__)

#endif

/* Typedefs for various integral numbers, just for code clarity */

typedef unsigned       ClassOpcode;             /* One opcode */

typedef unsigned char  ByteCode;                /* One byte from bytecodes */

typedef int            ByteOffset;              /* Byte offset */

typedef int            ClassConstant;           /* Constant pool kind */

typedef long           CrwPosition;             /* Position in class image */

typedef unsigned short CrwCpoolIndex;           /* Index into constant pool */

/* Misc support macros */

/* Given the position of an opcode, find the next 4byte boundary position */

#define NEXT_4BYTE_BOUNDARY(opcode_pos) (((opcode_pos)+4) & (~3))

#define LARGEST_INJECTION               (12*3) /* 3 injections at same site */

#define MAXIMUM_NEW_CPOOL_ENTRIES       64 /* don't add more than 32 entries */

/* Constant Pool Entry (internal table that mirrors pool in file image) */

typedef struct {

    const char *        ptr;            /* Pointer to any string */

    unsigned short      len;            /* Length of string */

    unsigned int        index1;         /* 1st 16 bit index or 32bit value. */

    unsigned int        index2;         /* 2nd 16 bit index or 32bit value. */

    ClassConstant       tag;            /* Tag or kind of entry. */

} CrwConstantPoolEntry;

struct MethodImage;

/* Class file image storage structure */

typedef struct CrwClassImage {

    /* Unique class number for this class */

    unsigned                    number;

    /* Name of class, given or gotten out of class image */

    const char *                name;

    /* Input and Output class images tracking */

    const unsigned char *       input;

    unsigned char *             output;

    CrwPosition                 input_len;

    CrwPosition                 output_len;

    CrwPosition                 input_position;

    CrwPosition                 output_position;

    /* Mirrored constant pool */

    CrwConstantPoolEntry *      cpool;

    CrwCpoolIndex               cpool_max_elements;             /* Max count */

    CrwCpoolIndex               cpool_count_plus_one;

    /* Input flags about class (e.g. is it a system class) */

    int                         system_class;

    /* Class access flags gotten from file. */

    unsigned                    access_flags;

    /* Names of classes and methods. */

    char* tclass_name;          /* Name of class that has tracker methods. */

    char* tclass_sig;           /* Signature of class */

    char* call_name;            /* Method name to call at offset 0 */

    char* call_sig;             /* Signature of this method */

    char* return_name;          /* Method name to call before any return */

    char* return_sig;           /* Signature of this method */

    char* obj_init_name;        /* Method name to call in Object <init> */

    char* obj_init_sig;         /* Signature of this method */

    char* newarray_name;        /* Method name to call after newarray opcodes */

    char* newarray_sig;         /* Signature of this method */

    /* Constant pool index values for new entries */

    CrwCpoolIndex               tracker_class_index;

    CrwCpoolIndex               object_init_tracker_index;

    CrwCpoolIndex               newarray_tracker_index;

    CrwCpoolIndex               call_tracker_index;

    CrwCpoolIndex               return_tracker_index;

    CrwCpoolIndex               class_number_index; /* Class number in pool */

    /* Count of injections made into this class */

    int                         injection_count;

    /* This class must be the java.lang.Object class */

    jboolean                    is_object_class;

    /* This class must be the java.lang.Thread class */

    jboolean                    is_thread_class;

    /* Callback functions */

    FatalErrorHandler           fatal_error_handler;

    MethodNumberRegister        mnum_callback;

    /* Table of method names and descr's */

    int                         method_count;

    const char **               method_name;

    const char **               method_descr;

    struct MethodImage *        current_mi;

} CrwClassImage;

/* Injection bytecodes (holds injected bytecodes for each code position) */

typedef struct {

    ByteCode *  code;

    ByteOffset  len;

} Injection;

/* Method transformation data (allocated/freed as each method is processed) */

typedef struct MethodImage {

    /* Back reference to Class image data. */

    CrwClassImage *     ci;

    /* Unique method number for this class. */

    unsigned            number;

    /* Method name and descr */

    const char *        name;

    const char *        descr;

    /* Map of input bytecode offsets to output bytecode offsets */

    ByteOffset *        map;

    /* Bytecode injections for each input bytecode offset */

    Injection *         injections;

    /* Widening setting for each input bytecode offset */

    signed char *       widening;

    /* Length of original input bytecodes, and new bytecodes. */

    ByteOffset          code_len;

    ByteOffset          new_code_len;

    /* Location in input where bytecodes are located. */

    CrwPosition         start_of_input_bytecodes;

    /* Original max_stack and new max stack */

    unsigned            max_stack;

    unsigned            new_max_stack;

    jboolean            object_init_method;

    jboolean            skip_call_return_sites;

    /* Method access flags gotten from file. */

    unsigned            access_flags;

} MethodImage;

/* ----------------------------------------------------------------- */

/* General support functions (memory and error handling) */

static void

fatal_error(CrwClassImage *ci, const char *message, const char *file, int line)

{

    if ( ci != NULL && ci->fatal_error_handler != NULL ) {

        (*ci->fatal_error_handler)(message, file, line);

    } else {

        /* Normal operation should NEVER reach here */

        /* NO CRW FATAL ERROR HANDLER! */

        (void)fprintf(stderr, "CRW: %s [%s:%d]\n", message, file, line);

    }

}

#if defined(DEBUG) || !defined(NDEBUG)

static void

assert_error(CrwClassImage *ci, const char *condition,

                 const char *file, int line)

{

    char buf[512];

    MethodImage *mi;

    ByteOffset byte_code_offset;

    mi = ci->current_mi;

    if ( mi != NULL ) {

        byte_code_offset = (ByteOffset)(mi->ci->input_position - mi->start_of_input_bytecodes);

    } else {

        byte_code_offset=-1;

    }

    (void)sprintf(buf,

                "CRW ASSERTION FAILURE: %s (%s:%s:%d)",

                condition,

                ci->name==NULL?"?":ci->name,

                (mi==NULL||mi->name==NULL)?"?":mi->name,

                byte_code_offset);

    fatal_error(ci, buf, file, line);

}

#endif

static void *

allocate(CrwClassImage *ci, int nbytes)

{

    void * ptr;

    if ( nbytes <= 0 ) {

        CRW_FATAL(ci, "Cannot allocate <= 0 bytes");

    }

    ptr = malloc(nbytes);

    if ( ptr == NULL ) {

        CRW_FATAL(ci, "Ran out of malloc memory");

    }

    return ptr;

}

static void *

reallocate(CrwClassImage *ci, void *optr, int nbytes)

{

    void * ptr;

    if ( optr == NULL ) {

        CRW_FATAL(ci, "Cannot deallocate NULL");

    }

    if ( nbytes <= 0 ) {

        CRW_FATAL(ci, "Cannot reallocate <= 0 bytes");

    }

    ptr = realloc(optr, nbytes);

    if ( ptr == NULL ) {

        CRW_FATAL(ci, "Ran out of malloc memory");

    }

    return ptr;

}

static void *

allocate_clean(CrwClassImage *ci, int nbytes)

{

    void * ptr;

    if ( nbytes <= 0 ) {

        CRW_FATAL(ci, "Cannot allocate <= 0 bytes");

    }

    ptr = calloc(nbytes, 1);

    if ( ptr == NULL ) {

        CRW_FATAL(ci, "Ran out of malloc memory");

    }

    return ptr;

}

static const char *

duplicate(CrwClassImage *ci, const char *str, int len)

{

    char *copy;

    copy = (char*)allocate(ci, len+1);

    (void)memcpy(copy, str, len);

    copy[len] = 0;

    return (const char *)copy;

}

static void

deallocate(CrwClassImage *ci, void *ptr)

{

    if ( ptr == NULL ) {

        CRW_FATAL(ci, "Cannot deallocate NULL");

    }

    (void)free(ptr);

}

/* ----------------------------------------------------------------- */

/* Functions for reading/writing bytes to/from the class images */

static unsigned

readU1(CrwClassImage *ci)

{

    CRW_ASSERT_CI(ci);

    return ((unsigned)(ci->input[ci->input_position++])) & 0xFF;

}

static unsigned

readU2(CrwClassImage *ci)

{

    unsigned res;

    res = readU1(ci);

    return (res << 8) + readU1(ci);

}

static signed short

readS2(CrwClassImage *ci)

{

    unsigned res;

    res = readU1(ci);

    return ((res << 8) + readU1(ci)) & 0xFFFF;

}

static unsigned

readU4(CrwClassImage *ci)

{

    unsigned res;

    res = readU2(ci);

    return (res << 16) + readU2(ci);

}

static void

writeU1(CrwClassImage *ci, unsigned val)  /* Only writes out lower 8 bits */

{

    CRW_ASSERT_CI(ci);

    if ( ci->output != NULL ) {

        ci->output[ci->output_position++] = val & 0xFF;

    }

}

static void

writeU2(CrwClassImage *ci, unsigned val)

{

    writeU1(ci, val >> 8);

    writeU1(ci, val);

}

static void

writeU4(CrwClassImage *ci, unsigned val)

{

    writeU2(ci, val >> 16);

    writeU2(ci, val);

}

static unsigned

copyU1(CrwClassImage *ci)

{

    unsigned value;

    value = readU1(ci);

    writeU1(ci, value);

    return value;

}

static unsigned

copyU2(CrwClassImage *ci)

{

    unsigned value;

    value = readU2(ci);

    writeU2(ci, value);

    return value;

}

static unsigned

copyU4(CrwClassImage *ci)

{

    unsigned value;

    value = readU4(ci);

    writeU4(ci, value);

    return value;

}

static void

copy(CrwClassImage *ci, unsigned count)

{

    CRW_ASSERT_CI(ci);

    if ( ci->output != NULL ) {

        (void)memcpy(ci->output+ci->output_position,

                     ci->input+ci->input_position, count);

        ci->output_position += count;

    }

    ci->input_position += count;

    CRW_ASSERT_CI(ci);

}

static void

skip(CrwClassImage *ci, unsigned count)

{

    CRW_ASSERT_CI(ci);

    ci->input_position += count;

}

static void

read_bytes(CrwClassImage *ci, void *bytes, unsigned count)

{

    CRW_ASSERT_CI(ci);

    CRW_ASSERT(ci, bytes!=NULL);

    (void)memcpy(bytes, ci->input+ci->input_position, count);

    ci->input_position += count;

}

static void

write_bytes(CrwClassImage *ci, void *bytes, unsigned count)

{

    CRW_ASSERT_CI(ci);

    CRW_ASSERT(ci, bytes!=NULL);

    if ( ci->output != NULL ) {

        (void)memcpy(ci->output+ci->output_position, bytes, count);

        ci->output_position += count;

    }

}

static void

random_writeU2(CrwClassImage *ci, CrwPosition pos, unsigned val)

{

    CrwPosition save_position;

    CRW_ASSERT_CI(ci);

    save_position = ci->output_position;

    ci->output_position = pos;

    writeU2(ci, val);

    ci->output_position = save_position;

}

static void

random_writeU4(CrwClassImage *ci, CrwPosition pos, unsigned val)

{

    CrwPosition save_position;

    CRW_ASSERT_CI(ci);

    save_position = ci->output_position;

    ci->output_position = pos;

    writeU4(ci, val);

    ci->output_position = save_position;

}

/* ----------------------------------------------------------------- */

/* Constant Pool handling functions. */

static void

fillin_cpool_entry(CrwClassImage *ci, CrwCpoolIndex i,

                   ClassConstant tag,

                   unsigned int index1, unsigned int index2,

                   const char *ptr, int len)