Java example source code file (java_crw_demo.c)
The java_crw_demo.c Java example source code
/*
* Copyright (c) 2003, 2013, 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);
}
abort();
}
#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)
{
CRW_ASSERT_CI(ci);
CRW_ASSERT(ci, i > 0 && i < ci->cpool_count_plus_one);
ci->cpool[i].tag = tag;
ci->cpool[i].index1 = index1;
ci->cpool[i].index2 = index2;
ci->cpool[i].ptr = ptr;
ci->cpool[i].len = (unsigned short)len;
}
static CrwCpoolIndex
add_new_cpool_entry(CrwClassImage *ci, ClassConstant tag,
unsigned int index1, unsigned int index2,
const char *str, int len)
{
CrwCpoolIndex i;
char *utf8 = NULL;
CRW_ASSERT_CI(ci);
i = ci->cpool_count_plus_one++;
/* NOTE: This implementation does not automatically expand the
* constant pool table beyond the expected number needed
* to handle this particular CrwTrackerInterface injections.
* See MAXIMUM_NEW_CPOOL_ENTRIES
*/
CRW_ASSERT(ci, ci->cpool_count_plus_one < ci->cpool_max_elements );
writeU1(ci, tag);
switch (tag) {
case JVM_CONSTANT_Class:
writeU2(ci, index1);
break;
case JVM_CONSTANT_String:
writeU2(ci, index1);
break;
case JVM_CONSTANT_Fieldref:
case JVM_CONSTANT_Methodref:
case JVM_CONSTANT_InterfaceMethodref:
case JVM_CONSTANT_Integer:
case JVM_CONSTANT_Float:
case JVM_CONSTANT_NameAndType:
writeU2(ci, index1);
writeU2(ci, index2);
break;
case JVM_CONSTANT_Long:
case JVM_CONSTANT_Double:
writeU4(ci, index1);
writeU4(ci, index2);
ci->cpool_count_plus_one++;
CRW_ASSERT(ci, ci->cpool_count_plus_one < ci->cpool_max_elements );
break;
case JVM_CONSTANT_Utf8:
CRW_ASSERT(ci, len==(len & 0xFFFF));
writeU2(ci, len);
write_bytes(ci, (void*)str, len);
utf8 = (char*)duplicate(ci, str, len);
break;
default:
CRW_FATAL(ci, "Unknown constant");
break;
}
fillin_cpool_entry(ci, i, tag, index1, index2, (const char *)utf8, len);
CRW_ASSERT(ci, i > 0 && i < ci->cpool_count_plus_one);
return i;
}
static CrwCpoolIndex
add_new_class_cpool_entry(CrwClassImage *ci, const char *class_name)
{
CrwCpoolIndex name_index;
CrwCpoolIndex class_index;
int len;
CRW_ASSERT_CI(ci);
CRW_ASSERT(ci, class_name!=NULL);
len = (int)strlen(class_name);
name_index = add_new_cpool_entry(ci, JVM_CONSTANT_Utf8, len, 0,
class_name, len);
class_index = add_new_cpool_entry(ci, JVM_CONSTANT_Class, name_index, 0,
NULL, 0);
return class_index;
}
static CrwCpoolIndex
add_new_method_cpool_entry(CrwClassImage *ci, CrwCpoolIndex class_index,
const char *name, const char *descr)
{
CrwCpoolIndex name_index;
CrwCpoolIndex descr_index;
CrwCpoolIndex name_type_index;
int len;
CRW_ASSERT_CI(ci);
CRW_ASSERT(ci, name!=NULL);
CRW_ASSERT(ci, descr!=NULL);
len = (int)strlen(name);
name_index =
add_new_cpool_entry(ci, JVM_CONSTANT_Utf8, len, 0, name, len);
len = (int)strlen(descr);
descr_index =
add_new_cpool_entry(ci, JVM_CONSTANT_Utf8, len, 0, descr, len);
name_type_index =
add_new_cpool_entry(ci, JVM_CONSTANT_NameAndType,
name_index, descr_index, NULL, 0);
return add_new_cpool_entry(ci, JVM_CONSTANT_Methodref,
class_index, name_type_index, NULL, 0);
}
static CrwConstantPoolEntry
cpool_entry(CrwClassImage *ci, CrwCpoolIndex c_index)
{
CRW_ASSERT_CI(ci);
CRW_ASSERT(ci, c_index > 0 && c_index < ci->cpool_count_plus_one);
return ci->cpool[c_index];
}
static void
cpool_setup(CrwClassImage *ci)
{
CrwCpoolIndex i;
CrwPosition cpool_output_position;
int count_plus_one;
CRW_ASSERT_CI(ci);
cpool_output_position = ci->output_position;
count_plus_one = copyU2(ci);
CRW_ASSERT(ci, count_plus_one>1);
ci->cpool_max_elements = count_plus_one+MAXIMUM_NEW_CPOOL_ENTRIES;
ci->cpool = (CrwConstantPoolEntry*)allocate_clean(ci,
(int)((ci->cpool_max_elements)*sizeof(CrwConstantPoolEntry)));
ci->cpool_count_plus_one = (CrwCpoolIndex)count_plus_one;
/* Index zero not in class file */
for (i = 1; i < count_plus_one; ++i) {
CrwCpoolIndex ipos;
ClassConstant tag;
unsigned int index1;
unsigned int index2;
unsigned len;
char * utf8;
char message[BUFSIZE];
ipos = i;
index1 = 0;
index2 = 0;
len = 0;
utf8 = NULL;
tag = copyU1(ci);
switch (tag) {
case JVM_CONSTANT_Class:
index1 = copyU2(ci);
break;
case JVM_CONSTANT_String:
index1 = copyU2(ci);
break;
case JVM_CONSTANT_Fieldref:
case JVM_CONSTANT_Methodref:
case JVM_CONSTANT_InterfaceMethodref:
case JVM_CONSTANT_Integer:
case JVM_CONSTANT_Float:
case JVM_CONSTANT_NameAndType:
index1 = copyU2(ci);
index2 = copyU2(ci);
break;
case JVM_CONSTANT_Long:
case JVM_CONSTANT_Double:
index1 = copyU4(ci);
index2 = copyU4(ci);
++i; /* // these take two CP entries - duh! */
break;
case JVM_CONSTANT_Utf8:
len = copyU2(ci);
index1 = (unsigned short)len;
utf8 = (char*)allocate(ci, len+1);
read_bytes(ci, (void*)utf8, len);
utf8[len] = 0;
write_bytes(ci, (void*)utf8, len);
break;
case JVM_CONSTANT_MethodType:
index1 = copyU2(ci);
break;
case JVM_CONSTANT_MethodHandle:
index1 = copyU1(ci);
index2 = copyU2(ci);
break;
case JVM_CONSTANT_InvokeDynamic:
index1 = copyU2(ci);
index2 = copyU2(ci);
break;
default:
snprintf(message, BUFSIZE, "Unknown tag: %d, at ipos %hu", tag, ipos);
CRW_FATAL(ci, message);
break;
}
fillin_cpool_entry(ci, ipos, tag, index1, index2, (const char *)utf8, len);
}
if (ci->call_name != NULL || ci->return_name != NULL) {
if ( ci->number != (ci->number & 0x7FFF) ) {
ci->class_number_index =
add_new_cpool_entry(ci, JVM_CONSTANT_Integer,
(ci->number>>16) & 0xFFFF, ci->number & 0xFFFF, NULL, 0);
}
}
if ( ci->tclass_name != NULL ) {
ci->tracker_class_index =
add_new_class_cpool_entry(ci, ci->tclass_name);
}
if (ci->obj_init_name != NULL) {
ci->object_init_tracker_index = add_new_method_cpool_entry(ci,
ci->tracker_class_index,
ci->obj_init_name,
ci->obj_init_sig);
}
if (ci->newarray_name != NULL) {
ci->newarray_tracker_index = add_new_method_cpool_entry(ci,
ci->tracker_class_index,
ci->newarray_name,
ci->newarray_sig);
}
if (ci->call_name != NULL) {
ci->call_tracker_index = add_new_method_cpool_entry(ci,
ci->tracker_class_index,
ci->call_name,
ci->call_sig);
}
if (ci->return_name != NULL) {
ci->return_tracker_index = add_new_method_cpool_entry(ci,
ci->tracker_class_index,
ci->return_name,
ci->return_sig);
}
random_writeU2(ci, cpool_output_position, ci->cpool_count_plus_one);
}
/* ----------------------------------------------------------------- */
/* Functions that create the bytecodes to inject */
static ByteOffset
push_pool_constant_bytecodes(ByteCode *bytecodes, CrwCpoolIndex index)
{
ByteOffset nbytes = 0;
if ( index == (index&0x7F) ) {
bytecodes[nbytes++] = (ByteCode)JVM_OPC_ldc;
} else {
bytecodes[nbytes++] = (ByteCode)JVM_OPC_ldc_w;
bytecodes[nbytes++] = (ByteCode)((index >> 8) & 0xFF);
}
bytecodes[nbytes++] = (ByteCode)(index & 0xFF);
return nbytes;
}
static ByteOffset
push_short_constant_bytecodes(ByteCode *bytecodes, unsigned number)
{
ByteOffset nbytes = 0;
if ( number <= 5 ) {
bytecodes[nbytes++] = (ByteCode)(JVM_OPC_iconst_0+number);
} else if ( number == (number&0x7F) ) {
bytecodes[nbytes++] = (ByteCode)JVM_OPC_bipush;
bytecodes[nbytes++] = (ByteCode)(number & 0xFF);
} else {
bytecodes[nbytes++] = (ByteCode)JVM_OPC_sipush;
bytecodes[nbytes++] = (ByteCode)((number >> 8) & 0xFF);
bytecodes[nbytes++] = (ByteCode)(number & 0xFF);
}
return nbytes;
}
static ByteOffset
injection_template(MethodImage *mi, ByteCode *bytecodes, ByteOffset max_nbytes,
CrwCpoolIndex method_index)
{
CrwClassImage * ci;
ByteOffset nbytes = 0;
unsigned max_stack;
int add_dup;
int add_aload;
int push_cnum;
int push_mnum;
ci = mi->ci;
CRW_ASSERT(ci, bytecodes!=NULL);
if ( method_index == 0 ) {
return 0;
}
if ( method_index == ci->newarray_tracker_index) {
max_stack = mi->max_stack + 1;
add_dup = JNI_TRUE;
add_aload = JNI_FALSE;
push_cnum = JNI_FALSE;
push_mnum = JNI_FALSE;
} else if ( method_index == ci->object_init_tracker_index) {
max_stack = mi->max_stack + 1;
add_dup = JNI_FALSE;
add_aload = JNI_TRUE;
push_cnum = JNI_FALSE;
push_mnum = JNI_FALSE;
} else {
max_stack = mi->max_stack + 2;
add_dup = JNI_FALSE;
add_aload = JNI_FALSE;
push_cnum = JNI_TRUE;
push_mnum = JNI_TRUE;
}
if ( add_dup ) {
bytecodes[nbytes++] = (ByteCode)JVM_OPC_dup;
}
if ( add_aload ) {
bytecodes[nbytes++] = (ByteCode)JVM_OPC_aload_0;
}
if ( push_cnum ) {
if ( ci->number == (ci->number & 0x7FFF) ) {
nbytes += push_short_constant_bytecodes(bytecodes+nbytes,
ci->number);
} else {
CRW_ASSERT(ci, ci->class_number_index!=0);
nbytes += push_pool_constant_bytecodes(bytecodes+nbytes,
ci->class_number_index);
}
}
if ( push_mnum ) {
nbytes += push_short_constant_bytecodes(bytecodes+nbytes,
mi->number);
}
bytecodes[nbytes++] = (ByteCode)JVM_OPC_invokestatic;
bytecodes[nbytes++] = (ByteCode)(method_index >> 8);
bytecodes[nbytes++] = (ByteCode)method_index;
bytecodes[nbytes] = 0;
CRW_ASSERT(ci, nbytes<max_nbytes);
/* Make sure the new max_stack is appropriate */
if ( max_stack > mi->new_max_stack ) {
mi->new_max_stack = max_stack;
}
return nbytes;
}
/* Called to create injection code at entry to a method */
static ByteOffset
entry_injection_code(MethodImage *mi, ByteCode *bytecodes, ByteOffset len)
{
CrwClassImage * ci;
ByteOffset nbytes = 0;
CRW_ASSERT_MI(mi);
ci = mi->ci;
if ( mi->object_init_method ) {
nbytes = injection_template(mi,
bytecodes, len, ci->object_init_tracker_index);
}
if ( !mi->skip_call_return_sites ) {
nbytes += injection_template(mi,
bytecodes+nbytes, len-nbytes, ci->call_tracker_index);
}
return nbytes;
}
/* Called to create injection code before an opcode */
static ByteOffset
before_injection_code(MethodImage *mi, ClassOpcode opcode,
ByteCode *bytecodes, ByteOffset len)
{
ByteOffset nbytes = 0;
CRW_ASSERT_MI(mi);
switch ( opcode ) {
case JVM_OPC_return:
case JVM_OPC_ireturn:
case JVM_OPC_lreturn:
case JVM_OPC_freturn:
case JVM_OPC_dreturn:
case JVM_OPC_areturn:
if ( !mi->skip_call_return_sites ) {
nbytes = injection_template(mi,
bytecodes, len, mi->ci->return_tracker_index);
}
break;
default:
break;
}
return nbytes;
}
/* Called to create injection code after an opcode */
static ByteOffset
after_injection_code(MethodImage *mi, ClassOpcode opcode,
ByteCode *bytecodes, ByteOffset len)
{
CrwClassImage* ci;
ByteOffset nbytes;
ci = mi->ci;
nbytes = 0;
CRW_ASSERT_MI(mi);
switch ( opcode ) {
case JVM_OPC_new:
/* Can't inject here cannot pass around uninitialized object */
break;
case JVM_OPC_newarray:
case JVM_OPC_anewarray:
case JVM_OPC_multianewarray:
nbytes = injection_template(mi,
bytecodes, len, ci->newarray_tracker_index);
break;
default:
break;
}
return nbytes;
}
/* Actually inject the bytecodes */
static void
inject_bytecodes(MethodImage *mi, ByteOffset at,
ByteCode *bytecodes, ByteOffset len)
{
Injection injection;
CrwClassImage *ci;
ci = mi->ci;
CRW_ASSERT_MI(mi);
CRW_ASSERT(ci, at <= mi->code_len);
injection = mi->injections[at];
CRW_ASSERT(ci, len <= LARGEST_INJECTION/2);
CRW_ASSERT(ci, injection.len+len <= LARGEST_INJECTION);
/* Either start an injection area or concatenate to what is there */
if ( injection.code == NULL ) {
CRW_ASSERT(ci, injection.len==0);
injection.code = (ByteCode *)allocate_clean(ci, LARGEST_INJECTION+1);
}
(void)memcpy(injection.code+injection.len, bytecodes, len);
injection.len += len;
injection.code[injection.len] = 0;
mi->injections[at] = injection;
ci->injection_count++;
}
/* ----------------------------------------------------------------- */
/* Method handling functions */
static MethodImage *
method_init(CrwClassImage *ci, unsigned mnum, ByteOffset code_len)
{
MethodImage * mi;
ByteOffset i;
mi = (MethodImage*)allocate_clean(ci, (int)sizeof(MethodImage));
mi->ci = ci;
mi->name = ci->method_name[mnum];
mi->descr = ci->method_descr[mnum];
mi->code_len = code_len;
mi->map = (ByteOffset*)allocate_clean(ci,
(int)((code_len+1)*sizeof(ByteOffset)));
for(i=0; i<=code_len; i++) {
mi->map[i] = i;
}
mi->widening = (signed char*)allocate_clean(ci, code_len+1);
mi->injections = (Injection *)allocate_clean(ci,
(int)((code_len+1)*sizeof(Injection)));
mi->number = mnum;
ci->current_mi = mi;
return mi;
}
static void
method_term(MethodImage *mi)
{
CrwClassImage *ci;
ci = mi->ci;
CRW_ASSERT_MI(mi);
if ( mi->map != NULL ) {
deallocate(ci, (void*)mi->map);
mi->map = NULL;
}
if ( mi->widening != NULL ) {
deallocate(ci, (void*)mi->widening);
mi->widening = NULL;
}
if ( mi->injections != NULL ) {
ByteOffset i;
for(i=0; i<= mi->code_len; i++) {
if ( mi->injections[i].code != NULL ) {
deallocate(ci, (void*)mi->injections[i].code);
mi->injections[i].code = NULL;
}
}
deallocate(ci, (void*)mi->injections);
mi->injections = NULL;
}
ci->current_mi = NULL;
deallocate(ci, (void*)mi);
}
static ByteOffset
input_code_offset(MethodImage *mi)
{
CRW_ASSERT_MI(mi);
return (ByteOffset)(mi->ci->input_position - mi->start_of_input_bytecodes);
}
static void
rewind_to_beginning_of_input_bytecodes(MethodImage *mi)
{
CRW_ASSERT_MI(mi);
mi->ci->input_position = mi->start_of_input_bytecodes;
}
/* Starting at original byte position 'at', add 'offset' to it's new
* location. This may be a negative value.
* NOTE: That this map is not the new bytecode location of the opcode
* but the new bytecode location that should be used when
* a goto or jump instruction was targeting the old bytecode
* location.
*/
static void
adjust_map(MethodImage *mi, ByteOffset at, ByteOffset offset)
{
ByteOffset i;
CRW_ASSERT_MI(mi);
for (i = at; i <= mi->code_len; ++i) {
mi->map[i] += offset;
}
}
static void
widen(MethodImage *mi, ByteOffset at, ByteOffset len)
{
int delta;
CRW_ASSERT(mi->ci, at <= mi->code_len);
delta = len - mi->widening[at];
/* Adjust everything from the current input location by delta */
adjust_map(mi, input_code_offset(mi), delta);
/* Mark at beginning of instruction */
mi->widening[at] = (signed char)len;
}
static void
verify_opc_wide(CrwClassImage *ci, ClassOpcode wopcode)
{
switch (wopcode) {
case JVM_OPC_aload: case JVM_OPC_astore:
case JVM_OPC_fload: case JVM_OPC_fstore:
case JVM_OPC_iload: case JVM_OPC_istore:
case JVM_OPC_lload: case JVM_OPC_lstore:
case JVM_OPC_dload: case JVM_OPC_dstore:
case JVM_OPC_ret: case JVM_OPC_iinc:
break;
default:
CRW_FATAL(ci, "Invalid opcode supplied to wide opcode");
break;
}
}
static unsigned
opcode_length(CrwClassImage *ci, ClassOpcode opcode)
{
/* Define array that holds length of an opcode */
static unsigned char _opcode_length[JVM_OPC_MAX+1] =
JVM_OPCODE_LENGTH_INITIALIZER;
if ( opcode > JVM_OPC_MAX ) {
CRW_FATAL(ci, "Invalid opcode supplied to opcode_length()");
}
return _opcode_length[opcode];
}
/* Walk one instruction and inject instrumentation */
static void
inject_for_opcode(MethodImage *mi)
{
CrwClassImage * ci;
ClassOpcode opcode;
int pos;
CRW_ASSERT_MI(mi);
ci = mi->ci;
pos = input_code_offset(mi);
opcode = readU1(ci);
if (opcode == JVM_OPC_wide) {
ClassOpcode wopcode;
wopcode = readU1(ci);
/* lvIndex not used */
(void)readU2(ci);
verify_opc_wide(ci, wopcode);
if ( wopcode==JVM_OPC_iinc ) {
(void)readU1(ci);
(void)readU1(ci);
}
} else {
ByteCode bytecodes[LARGEST_INJECTION+1];
int header;
int instr_len;
int low;
int high;
int npairs;
ByteOffset len;
/* Get bytecodes to inject before this opcode */
len = before_injection_code(mi, opcode, bytecodes, (int)sizeof(bytecodes));
if ( len > 0 ) {
inject_bytecodes(mi, pos, bytecodes, len);
/* Adjust map after processing this opcode */
}
/* Process this opcode */
switch (opcode) {
case JVM_OPC_tableswitch:
header = NEXT_4BYTE_BOUNDARY(pos);
skip(ci, header - (pos+1));
(void)readU4(ci);
low = readU4(ci);
high = readU4(ci);
skip(ci, (high+1-low) * 4);
break;
case JVM_OPC_lookupswitch:
header = NEXT_4BYTE_BOUNDARY(pos);
skip(ci, header - (pos+1));
(void)readU4(ci);
npairs = readU4(ci);
skip(ci, npairs * 8);
break;
default:
instr_len = opcode_length(ci, opcode);
skip(ci, instr_len-1);
break;
}
/* Get position after this opcode is processed */
pos = input_code_offset(mi);
/* Adjust for any before_injection_code() */
if ( len > 0 ) {
/* Adjust everything past this opcode.
* Why past it? Because we want any jumps to this bytecode loc
* to go to the injected code, not where the opcode
* was moved too.
* Consider a 'return' opcode that is jumped too.
* NOTE: This may not be correct in all cases, but will
* when we are only dealing with non-variable opcodes
* like the return opcodes. Be careful if the
* before_injection_code() changes to include other
* opcodes that have variable length.
*/
adjust_map(mi, pos, len);
}
/* Get bytecodes to inject after this opcode */
len = after_injection_code(mi, opcode, bytecodes, (int)sizeof(bytecodes));
if ( len > 0 ) {
inject_bytecodes(mi, pos, bytecodes, len);
/* Adjust for any after_injection_code() */
adjust_map(mi, pos, len);
}
}
}
/* Map original bytecode location to it's new location. (See adjust_map()). */
static ByteOffset
method_code_map(MethodImage *mi, ByteOffset pos)
{
CRW_ASSERT_MI(mi);
CRW_ASSERT(mi->ci, pos <= mi->code_len);
return mi->map[pos];
}
static int
adjust_instruction(MethodImage *mi)
{
CrwClassImage * ci;
ClassOpcode opcode;
int pos;
int new_pos;
CRW_ASSERT_MI(mi);
ci = mi->ci;
pos = input_code_offset(mi);
new_pos = method_code_map(mi,pos);
opcode = readU1(ci);
if (opcode == JVM_OPC_wide) {
ClassOpcode wopcode;
wopcode = readU1(ci);
/* lvIndex not used */
(void)readU2(ci);
verify_opc_wide(ci, wopcode);
if ( wopcode==JVM_OPC_iinc ) {
(void)readU1(ci);
(void)readU1(ci);
}
} else {
int widened;
int header;
int newHeader;
int low;
int high;
int new_pad;
int old_pad;
int delta;
int new_delta;
int delta_pad;
int npairs;
int instr_len;
switch (opcode) {
case JVM_OPC_tableswitch:
widened = mi->widening[pos];
header = NEXT_4BYTE_BOUNDARY(pos);
newHeader = NEXT_4BYTE_BOUNDARY(new_pos);
skip(ci, header - (pos+1));
delta = readU4(ci);
low = readU4(ci);
high = readU4(ci);
skip(ci, (high+1-low) * 4);
new_pad = newHeader - new_pos;
old_pad = header - pos;
delta_pad = new_pad - old_pad;
if (widened != delta_pad) {
widen(mi, pos, delta_pad);
return 0;
}
break;
case JVM_OPC_lookupswitch:
widened = mi->widening[pos];
header = NEXT_4BYTE_BOUNDARY(pos);
newHeader = NEXT_4BYTE_BOUNDARY(new_pos);
skip(ci, header - (pos+1));
delta = readU4(ci);
npairs = readU4(ci);
skip(ci, npairs * 8);
new_pad = newHeader - new_pos;
old_pad = header - pos;
delta_pad = new_pad - old_pad;
if (widened != delta_pad) {
widen(mi, pos, delta_pad);
return 0;
}
break;
case JVM_OPC_jsr: case JVM_OPC_goto:
case JVM_OPC_ifeq: case JVM_OPC_ifge: case JVM_OPC_ifgt:
case JVM_OPC_ifle: case JVM_OPC_iflt: case JVM_OPC_ifne:
case JVM_OPC_if_icmpeq: case JVM_OPC_if_icmpne: case JVM_OPC_if_icmpge:
case JVM_OPC_if_icmpgt: case JVM_OPC_if_icmple: case JVM_OPC_if_icmplt:
case JVM_OPC_if_acmpeq: case JVM_OPC_if_acmpne:
case JVM_OPC_ifnull: case JVM_OPC_ifnonnull:
widened = mi->widening[pos];
delta = readS2(ci);
if (widened == 0) {
new_delta = method_code_map(mi,pos+delta) - new_pos;
if ((new_delta < -32768) || (new_delta > 32767)) {
switch (opcode) {
case JVM_OPC_jsr: case JVM_OPC_goto:
widen(mi, pos, 2);
break;
default:
widen(mi, pos, 5);
break;
}
return 0;
}
}
break;
case JVM_OPC_jsr_w:
case JVM_OPC_goto_w:
(void)readU4(ci);
break;
default:
instr_len = opcode_length(ci, opcode);
skip(ci, instr_len-1);
break;
}
}
return 1;
}
static void
write_instruction(MethodImage *mi)
{
CrwClassImage * ci;
ClassOpcode opcode;
ByteOffset new_code_len;
int pos;
int new_pos;
CRW_ASSERT_MI(mi);
ci = mi->ci;
pos = input_code_offset(mi);
new_pos = method_code_map(mi,pos);
new_code_len = mi->injections[pos].len;
if (new_code_len > 0) {
write_bytes(ci, (void*)mi->injections[pos].code, new_code_len);
}
opcode = readU1(ci);
if (opcode == JVM_OPC_wide) {
ClassOpcode wopcode;
writeU1(ci, opcode);
wopcode = copyU1(ci);
/* lvIndex not used */
(void)copyU2(ci);
verify_opc_wide(ci, wopcode);
if ( wopcode==JVM_OPC_iinc ) {
(void)copyU1(ci);
(void)copyU1(ci);
}
} else {
ClassOpcode new_opcode;
int header;
int newHeader;
int low;
int high;
int i;
int npairs;
int widened;
int instr_len;
int delta;
int new_delta;
switch (opcode) {
case JVM_OPC_tableswitch:
header = NEXT_4BYTE_BOUNDARY(pos);
newHeader = NEXT_4BYTE_BOUNDARY(new_pos);
skip(ci, header - (pos+1));
delta = readU4(ci);
new_delta = method_code_map(mi,pos+delta) - new_pos;
low = readU4(ci);
high = readU4(ci);
writeU1(ci, opcode);
for (i = new_pos+1; i < newHeader; ++i) {
writeU1(ci, 0);
}
writeU4(ci, new_delta);
writeU4(ci, low);
writeU4(ci, high);
for (i = low; i <= high; ++i) {
delta = readU4(ci);
new_delta = method_code_map(mi,pos+delta) - new_pos;
writeU4(ci, new_delta);
}
break;
case JVM_OPC_lookupswitch:
header = NEXT_4BYTE_BOUNDARY(pos);
newHeader = NEXT_4BYTE_BOUNDARY(new_pos);
skip(ci, header - (pos+1));
delta = readU4(ci);
new_delta = method_code_map(mi,pos+delta) - new_pos;
npairs = readU4(ci);
writeU1(ci, opcode);
for (i = new_pos+1; i < newHeader; ++i) {
writeU1(ci, 0);
}
writeU4(ci, new_delta);
writeU4(ci, npairs);
for (i = 0; i< npairs; ++i) {
unsigned match = readU4(ci);
delta = readU4(ci);
new_delta = method_code_map(mi,pos+delta) - new_pos;
writeU4(ci, match);
writeU4(ci, new_delta);
}
break;
case JVM_OPC_jsr: case JVM_OPC_goto:
case JVM_OPC_ifeq: case JVM_OPC_ifge: case JVM_OPC_ifgt:
case JVM_OPC_ifle: case JVM_OPC_iflt: case JVM_OPC_ifne:
case JVM_OPC_if_icmpeq: case JVM_OPC_if_icmpne: case JVM_OPC_if_icmpge:
case JVM_OPC_if_icmpgt: case JVM_OPC_if_icmple: case JVM_OPC_if_icmplt:
case JVM_OPC_if_acmpeq: case JVM_OPC_if_acmpne:
case JVM_OPC_ifnull: case JVM_OPC_ifnonnull:
widened = mi->widening[pos];
delta = readS2(ci);
new_delta = method_code_map(mi,pos+delta) - new_pos;
new_opcode = opcode;
if (widened == 0) {
writeU1(ci, opcode);
writeU2(ci, new_delta);
} else if (widened == 2) {
switch (opcode) {
case JVM_OPC_jsr:
new_opcode = JVM_OPC_jsr_w;
break;
case JVM_OPC_goto:
new_opcode = JVM_OPC_goto_w;
break;
default:
CRW_FATAL(ci, "unexpected opcode");
break;
}
writeU1(ci, new_opcode);
writeU4(ci, new_delta);
} else if (widened == 5) {
switch (opcode) {
case JVM_OPC_ifeq:
new_opcode = JVM_OPC_ifne;
break;
case JVM_OPC_ifge:
new_opcode = JVM_OPC_iflt;
break;
case JVM_OPC_ifgt:
new_opcode = JVM_OPC_ifle;
break;
case JVM_OPC_ifle:
new_opcode = JVM_OPC_ifgt;
break;
case JVM_OPC_iflt:
new_opcode = JVM_OPC_ifge;
break;
case JVM_OPC_ifne:
new_opcode = JVM_OPC_ifeq;
break;
case JVM_OPC_if_icmpeq:
new_opcode = JVM_OPC_if_icmpne;
break;
case JVM_OPC_if_icmpne:
new_opcode = JVM_OPC_if_icmpeq;
break;
case JVM_OPC_if_icmpge:
new_opcode = JVM_OPC_if_icmplt;
break;
case JVM_OPC_if_icmpgt:
new_opcode = JVM_OPC_if_icmple;
break;
case JVM_OPC_if_icmple:
new_opcode = JVM_OPC_if_icmpgt;
break;
case JVM_OPC_if_icmplt:
new_opcode = JVM_OPC_if_icmpge;
break;
case JVM_OPC_if_acmpeq:
new_opcode = JVM_OPC_if_acmpne;
break;
case JVM_OPC_if_acmpne:
new_opcode = JVM_OPC_if_acmpeq;
break;
case JVM_OPC_ifnull:
new_opcode = JVM_OPC_ifnonnull;
break;
case JVM_OPC_ifnonnull:
new_opcode = JVM_OPC_ifnull;
break;
default:
CRW_FATAL(ci, "Unexpected opcode");
break;
}
writeU1(ci, new_opcode); /* write inverse branch */
writeU2(ci, 3 + 5); /* beyond if and goto_w */
writeU1(ci, JVM_OPC_goto_w); /* add a goto_w */
writeU4(ci, new_delta-3); /* write new and wide delta */
} else {
CRW_FATAL(ci, "Unexpected widening");
}
break;
case JVM_OPC_jsr_w:
case JVM_OPC_goto_w:
delta = readU4(ci);
new_delta = method_code_map(mi,pos+delta) - new_pos;
writeU1(ci, opcode);
writeU4(ci, new_delta);
break;
default:
instr_len = opcode_length(ci, opcode);
writeU1(ci, opcode);
copy(ci, instr_len-1);
break;
}
}
}
static void
method_inject_and_write_code(MethodImage *mi)
{
ByteCode bytecodes[LARGEST_INJECTION+1];
ByteOffset len;
CRW_ASSERT_MI(mi);
/* Do injections */
rewind_to_beginning_of_input_bytecodes(mi);
len = entry_injection_code(mi, bytecodes, (int)sizeof(bytecodes));
if ( len > 0 ) {
int pos;
pos = 0;
inject_bytecodes(mi, pos, bytecodes, len);
/* Adjust pos 0 to map to new pos 0, you never want to
* jump into this entry code injection. So the new pos 0
* will be past this entry_injection_code().
*/
adjust_map(mi, pos, len); /* Inject before behavior */
}
while (input_code_offset(mi) < mi->code_len) {
inject_for_opcode(mi);
}
/* Adjust instructions */
rewind_to_beginning_of_input_bytecodes(mi);
while (input_code_offset(mi) < mi->code_len) {
if (!adjust_instruction(mi)) {
rewind_to_beginning_of_input_bytecodes(mi);
}
}
/* Write new instructions */
rewind_to_beginning_of_input_bytecodes(mi);
while (input_code_offset(mi) < mi->code_len) {
write_instruction(mi);
}
}
static void
copy_attribute(CrwClassImage *ci)
{
int len;
(void)copyU2(ci);
len = copyU4(ci);
copy(ci, len);
}
static void
copy_attributes(CrwClassImage *ci)
{
unsigned i;
unsigned count;
count = copyU2(ci);
for (i = 0; i < count; ++i) {
copy_attribute(ci);
}
}
static void
copy_all_fields(CrwClassImage *ci)
{
unsigned i;
unsigned count;
count = copyU2(ci);
for (i = 0; i < count; ++i) {
/* access, name, descriptor */
copy(ci, 6);
copy_attributes(ci);
}
}
static void
write_line_table(MethodImage *mi)
{
unsigned i;
unsigned count;
CrwClassImage * ci;
CRW_ASSERT_MI(mi);
ci = mi->ci;
(void)copyU4(ci);
count = copyU2(ci);
for(i=0; i<count; i++) {
ByteOffset start_pc;
ByteOffset new_start_pc;
start_pc = readU2(ci);
if ( start_pc == 0 ) {
new_start_pc = 0; /* Don't skip entry injection code. */
} else {
new_start_pc = method_code_map(mi, start_pc);
}
writeU2(ci, new_start_pc);
(void)copyU2(ci);
}
}
/* Used for LocalVariableTable and LocalVariableTypeTable attributes */
static void
write_var_table(MethodImage *mi)
{
unsigned i;
unsigned count;
CrwClassImage * ci;
CRW_ASSERT_MI(mi);
ci = mi->ci;
(void)copyU4(ci);
count = copyU2(ci);
for(i=0; i<count; i++) {
ByteOffset start_pc;
ByteOffset new_start_pc;
ByteOffset length;
ByteOffset new_length;
ByteOffset end_pc;
ByteOffset new_end_pc;
start_pc = readU2(ci);
length = readU2(ci);
if ( start_pc == 0 ) {
new_start_pc = 0; /* Don't skip entry injection code. */
} else {
new_start_pc = method_code_map(mi, start_pc);
}
end_pc = start_pc + length;
new_end_pc = method_code_map(mi, end_pc);
new_length = new_end_pc - new_start_pc;
writeU2(ci, new_start_pc);
writeU2(ci, new_length);
(void)copyU2(ci);
(void)copyU2(ci);
(void)copyU2(ci);
}
}
/* The uoffset field is u2 or u4 depending on the code_len.
* Note that the code_len is likely changing, so be careful here.
*/
static unsigned
readUoffset(MethodImage *mi)
{
if ( mi->code_len > 65535 ) {
return readU4(mi->ci);
}
return readU2(mi->ci);
}
static void
writeUoffset(MethodImage *mi, unsigned val)
{
if ( mi->new_code_len > 65535 ) {
writeU4(mi->ci, val);
}
writeU2(mi->ci, val);
}
static unsigned
copyUoffset(MethodImage *mi)
{
unsigned uoffset;
uoffset = readUoffset(mi);
writeUoffset(mi, uoffset);
return uoffset;
}
/* Copy over verification_type_info structure */
static void
copy_verification_types(MethodImage *mi, int ntypes)
{
/* If there were ntypes, we just copy that over, no changes */
if ( ntypes > 0 ) {
int j;
for ( j = 0 ; j < ntypes ; j++ ) {
unsigned tag;
tag = copyU1(mi->ci);
switch ( tag ) {
case JVM_ITEM_Object:
(void)copyU2(mi->ci); /* Constant pool entry */
break;
case JVM_ITEM_Uninitialized:
/* Code offset for 'new' opcode is for this object */
writeUoffset(mi, method_code_map(mi, readUoffset(mi)));
break;
}
}
}
}
/* Process the StackMapTable attribute. We didn't add any basic blocks
* so the frame count remains the same but we may need to process the
* frame types due to offset changes putting things out of range.
*/
static void
write_stackmap_table(MethodImage *mi)
{
CrwClassImage *ci;
CrwPosition save_position;
ByteOffset last_pc;
ByteOffset last_new_pc;
unsigned i;
unsigned attr_len;
unsigned new_attr_len;
unsigned count;
unsigned delta_adj;
CRW_ASSERT_MI(mi);
ci = mi->ci;
/* Save the position of the attribute length so we can fix it later */
save_position = ci->output_position;
attr_len = copyU4(ci);
count = copyUoffset(mi); /* uoffset: number_of_entries */
if ( count == 0 ) {
CRW_ASSERT(ci, attr_len==2);
return;
}
/* Process entire stackmap */
last_pc = 0;
last_new_pc = 0;
delta_adj = 0;
for ( i = 0 ; i < count ; i++ ) {
ByteOffset new_pc=0; /* new pc in instrumented code */
unsigned ft; /* frame_type */
int delta=0; /* pc delta */
int new_delta=0; /* new pc delta */
ft = readU1(ci);
if ( ft <= 63 ) {
/* Frame Type: same_frame ([0,63]) */
unsigned new_ft; /* new frame_type */
delta = (delta_adj + ft);
new_pc = method_code_map(mi, last_pc + delta);
new_delta = new_pc - last_new_pc;
new_ft = (new_delta - delta_adj);
if ( new_ft > 63 ) {
/* Change to same_frame_extended (251) */
new_ft = 251;
writeU1(ci, new_ft);
writeUoffset(mi, (new_delta - delta_adj));
} else {
writeU1(ci, new_ft);
}
} else if ( ft >= 64 && ft <= 127 ) {
/* Frame Type: same_locals_1_stack_item_frame ([64,127]) */
unsigned new_ft; /* new frame_type */
delta = (delta_adj + ft - 64);
new_pc = method_code_map(mi, last_pc + delta);
new_delta = new_pc - last_new_pc;
if ( (new_delta - delta_adj) > 63 ) {
/* Change to same_locals_1_stack_item_frame_extended (247) */
new_ft = 247;
writeU1(ci, new_ft);
writeUoffset(mi, (new_delta - delta_adj));
} else {
new_ft = (new_delta - delta_adj) + 64;
writeU1(ci, new_ft);
}
copy_verification_types(mi, 1);
} else if ( ft >= 128 && ft <= 246 ) {
/* Frame Type: reserved_for_future_use ([128,246]) */
CRW_FATAL(ci, "Unknown frame type in StackMapTable attribute");
} else if ( ft == 247 ) {
/* Frame Type: same_locals_1_stack_item_frame_extended (247) */
delta = (delta_adj + readUoffset(mi));
new_pc = method_code_map(mi, last_pc + delta);
new_delta = new_pc - last_new_pc;
writeU1(ci, ft);
writeUoffset(mi, (new_delta - delta_adj));
copy_verification_types(mi, 1);
} else if ( ft >= 248 && ft <= 250 ) {
/* Frame Type: chop_frame ([248,250]) */
delta = (delta_adj + readUoffset(mi));
new_pc = method_code_map(mi, last_pc + delta);
new_delta = new_pc - last_new_pc;
writeU1(ci, ft);
writeUoffset(mi, (new_delta - delta_adj));
} else if ( ft == 251 ) {
/* Frame Type: same_frame_extended (251) */
delta = (delta_adj + readUoffset(mi));
new_pc = method_code_map(mi, last_pc + delta);
new_delta = new_pc - last_new_pc;
writeU1(ci, ft);
writeUoffset(mi, (new_delta - delta_adj));
} else if ( ft >= 252 && ft <= 254 ) {
/* Frame Type: append_frame ([252,254]) */
delta = (delta_adj + readUoffset(mi));
new_pc = method_code_map(mi, last_pc + delta);
new_delta = new_pc - last_new_pc;
writeU1(ci, ft);
writeUoffset(mi, (new_delta - delta_adj));
copy_verification_types(mi, (ft - 251));
} else if ( ft == 255 ) {
unsigned ntypes;
/* Frame Type: full_frame (255) */
delta = (delta_adj + readUoffset(mi));
new_pc = method_code_map(mi, last_pc + delta);
new_delta = new_pc - last_new_pc;
writeU1(ci, ft);
writeUoffset(mi, (new_delta - delta_adj));
ntypes = copyU2(ci); /* ulocalvar */
copy_verification_types(mi, ntypes);
ntypes = copyU2(ci); /* ustack */
copy_verification_types(mi, ntypes);
}
/* Update last_pc and last_new_pc (save on calls to method_code_map) */
CRW_ASSERT(ci, delta >= 0);
CRW_ASSERT(ci, new_delta >= 0);
last_pc += delta;
last_new_pc = new_pc;
CRW_ASSERT(ci, last_pc <= mi->code_len);
CRW_ASSERT(ci, last_new_pc <= mi->new_code_len);
/* Delta adjustment, all deltas are -1 now in attribute */
delta_adj = 1;
}
/* Update the attribute length */
new_attr_len = ci->output_position - (save_position + 4);
CRW_ASSERT(ci, new_attr_len >= attr_len);
random_writeU4(ci, save_position, new_attr_len);
}
/* Process the CLDC StackMap attribute. We didn't add any basic blocks
* so the frame count remains the same but we may need to process the
* frame types due to offset changes putting things out of range.
*/
static void
write_cldc_stackmap_table(MethodImage *mi)
{
CrwClassImage *ci;
CrwPosition save_position;
unsigned i;
unsigned attr_len;
unsigned new_attr_len;
unsigned count;
CRW_ASSERT_MI(mi);
ci = mi->ci;
/* Save the position of the attribute length so we can fix it later */
save_position = ci->output_position;
attr_len = copyU4(ci);
count = copyUoffset(mi); /* uoffset: number_of_entries */
if ( count == 0 ) {
CRW_ASSERT(ci, attr_len==2);
return;
}
/* Process entire stackmap */
for ( i = 0 ; i < count ; i++ ) {
unsigned ntypes;
writeUoffset(mi, method_code_map(mi, readUoffset(mi)));
ntypes = copyU2(ci); /* ulocalvar */
copy_verification_types(mi, ntypes);
ntypes = copyU2(ci); /* ustack */
copy_verification_types(mi, ntypes);
}
/* Update the attribute length */
new_attr_len = ci->output_position - (save_position + 4);
CRW_ASSERT(ci, new_attr_len >= attr_len);
random_writeU4(ci, save_position, new_attr_len);
}
static void
method_write_exception_table(MethodImage *mi)
{
unsigned i;
unsigned count;
CrwClassImage * ci;
CRW_ASSERT_MI(mi);
ci = mi->ci;
count = copyU2(ci);
for(i=0; i<count; i++) {
ByteOffset start_pc;
ByteOffset new_start_pc;
ByteOffset end_pc;
ByteOffset new_end_pc;
ByteOffset handler_pc;
ByteOffset new_handler_pc;
start_pc = readU2(ci);
end_pc = readU2(ci);
handler_pc = readU2(ci);
new_start_pc = method_code_map(mi, start_pc);
new_end_pc = method_code_map(mi, end_pc);
new_handler_pc = method_code_map(mi, handler_pc);
writeU2(ci, new_start_pc);
writeU2(ci, new_end_pc);
writeU2(ci, new_handler_pc);
(void)copyU2(ci);
}
}
static int
attribute_match(CrwClassImage *ci, CrwCpoolIndex name_index, const char *name)
{
CrwConstantPoolEntry cs;
int len;
CRW_ASSERT_CI(ci);
CRW_ASSERT(ci, name!=NULL);
len = (int)strlen(name);
cs = cpool_entry(ci, name_index);
if ( cs.len==len && strncmp(cs.ptr, name, len)==0) {
return 1;
}
return 0;
}
static void
method_write_code_attribute(MethodImage *mi)
{
CrwClassImage * ci;
CrwCpoolIndex name_index;
CRW_ASSERT_MI(mi);
ci = mi->ci;
name_index = copyU2(ci);
if ( attribute_match(ci, name_index, "LineNumberTable") ) {
write_line_table(mi);
} else if ( attribute_match(ci, name_index, "LocalVariableTable") ) {
write_var_table(mi);
} else if ( attribute_match(ci, name_index, "LocalVariableTypeTable") ) {
write_var_table(mi); /* Exact same format as the LocalVariableTable */
} else if ( attribute_match(ci, name_index, "StackMapTable") ) {
write_stackmap_table(mi);
} else if ( attribute_match(ci, name_index, "StackMap") ) {
write_cldc_stackmap_table(mi);
} else {
unsigned len;
len = copyU4(ci);
copy(ci, len);
}
}
static int
is_init_method(const char *name)
{
if ( name!=NULL && strcmp(name,"<init>")==0 ) {
return JNI_TRUE;
}
return JNI_FALSE;
}
static int
is_clinit_method(const char *name)
{
if ( name!=NULL && strcmp(name,"<clinit>")==0 ) {
return JNI_TRUE;
}
return JNI_FALSE;
}
static int
is_finalize_method(const char *name)
{
if ( name!=NULL && strcmp(name,"finalize")==0 ) {
return JNI_TRUE;
}
return JNI_FALSE;
}
static int
skip_method(CrwClassImage *ci, const char *name,
unsigned access_flags, ByteOffset code_len,
int system_class, jboolean *pskip_call_return_sites)
{
*pskip_call_return_sites = JNI_FALSE;
if ( system_class ) {
if ( code_len == 1 && is_init_method(name) ) {
return JNI_TRUE;
} else if ( code_len == 1 && is_finalize_method(name) ) {
return JNI_TRUE;
} else if ( is_clinit_method(name) ) {
return JNI_TRUE;
} else if ( ci->is_thread_class && strcmp(name,"currentThread")==0 ) {
return JNI_TRUE;
}
/*
if ( access_flags & JVM_ACC_PRIVATE ) {
*pskip_call_return_sites = JNI_TRUE;
}
*/
}
return JNI_FALSE;
}
/* Process all code attributes */
static void
method_write_bytecodes(CrwClassImage *ci, unsigned mnum, unsigned access_flags)
{
CrwPosition output_attr_len_position;
CrwPosition output_max_stack_position;
CrwPosition output_code_len_position;
CrwPosition start_of_output_bytecodes;
unsigned i;
unsigned attr_len;
unsigned max_stack;
ByteOffset code_len;
unsigned attr_count;
unsigned new_attr_len;
MethodImage * mi;
jboolean object_init_method;
jboolean skip_call_return_sites;
CRW_ASSERT_CI(ci);
/* Attribute Length */
output_attr_len_position = ci->output_position;
attr_len = copyU4(ci);
/* Max Stack */
output_max_stack_position = ci->output_position;
max_stack = copyU2(ci);
/* Max Locals */
(void)copyU2(ci);
/* Code Length */
output_code_len_position = ci->output_position;
code_len = copyU4(ci);
start_of_output_bytecodes = ci->output_position;
/* Some methods should not be instrumented */
object_init_method = JNI_FALSE;
skip_call_return_sites = JNI_FALSE;
if ( ci->is_object_class &&
is_init_method(ci->method_name[mnum]) &&
strcmp(ci->method_descr[mnum],"()V")==0 ) {
object_init_method = JNI_TRUE;
skip_call_return_sites = JNI_TRUE;
} else if ( skip_method(ci, ci->method_name[mnum], access_flags,
code_len, ci->system_class, &skip_call_return_sites) ) {
/* Copy remainder minus already copied, the U2 max_stack,
* U2 max_locals, and U4 code_length fields have already
* been processed.
*/
copy(ci, attr_len - (2+2+4));
return;
}
/* Start Injection */
mi = method_init(ci, mnum, code_len);
mi->object_init_method = object_init_method;
mi->access_flags = access_flags;
mi->skip_call_return_sites = skip_call_return_sites;
/* Save the current position as the start of the input bytecodes */
mi->start_of_input_bytecodes = ci->input_position;
/* The max stack may increase */
mi->max_stack = max_stack;
mi->new_max_stack = max_stack;
/* Adjust all code offsets */
method_inject_and_write_code(mi);
/* Fix up code length (save new_code_len for later attribute processing) */
mi->new_code_len = (int)(ci->output_position - start_of_output_bytecodes);
random_writeU4(ci, output_code_len_position, mi->new_code_len);
/* Fixup max stack */
CRW_ASSERT(ci, mi->new_max_stack <= 0xFFFF);
random_writeU2(ci, output_max_stack_position, mi->new_max_stack);
/* Copy exception table */
method_write_exception_table(mi);
/* Copy code attributes (needs mi->new_code_len) */
attr_count = copyU2(ci);
for (i = 0; i < attr_count; ++i) {
method_write_code_attribute(mi);
}
/* Fix up attribute length */
new_attr_len = (int)(ci->output_position - (output_attr_len_position + 4));
random_writeU4(ci, output_attr_len_position, new_attr_len);
/* Free method data */
method_term(mi);
mi = NULL;
}
static void
method_write(CrwClassImage *ci, unsigned mnum)
{
unsigned i;
unsigned access_flags;
CrwCpoolIndex name_index;
CrwCpoolIndex descr_index;
unsigned attr_count;
access_flags = copyU2(ci);
name_index = copyU2(ci);
ci->method_name[mnum] = cpool_entry(ci, name_index).ptr;
descr_index = copyU2(ci);
ci->method_descr[mnum] = cpool_entry(ci, descr_index).ptr;
attr_count = copyU2(ci);
for (i = 0; i < attr_count; ++i) {
CrwCpoolIndex name_index;
name_index = copyU2(ci);
if ( attribute_match(ci, name_index, "Code") ) {
method_write_bytecodes(ci, mnum, access_flags);
} else {
unsigned len;
len = copyU4(ci);
copy(ci, len);
}
}
}
static void
method_write_all(CrwClassImage *ci)
{
unsigned i;
unsigned count;
count = copyU2(ci);
ci->method_count = count;
if ( count > 0 ) {
ci->method_name = (const char **)allocate_clean(ci, count*(int)sizeof(const char*));
ci->method_descr = (const char **)allocate_clean(ci, count*(int)sizeof(const char*));
}
for (i = 0; i < count; ++i) {
method_write(ci, i);
}
if ( ci->mnum_callback != NULL ) {
(*(ci->mnum_callback))(ci->number, ci->method_name, ci->method_descr,
count);
}
}
/* ------------------------------------------------------------------- */
/* Cleanup function. */
static void
cleanup(CrwClassImage *ci)
{
CRW_ASSERT_CI(ci);
if ( ci->name != NULL ) {
deallocate(ci, (void*)ci->name);
ci->name = NULL;
}
if ( ci->method_name != NULL ) {
deallocate(ci, (void*)ci->method_name);
ci->method_name = NULL;
}
if ( ci->method_descr != NULL ) {
deallocate(ci, (void*)ci->method_descr);
ci->method_descr = NULL;
}
if ( ci->cpool != NULL ) {
CrwCpoolIndex i;
for(i=0; i<ci->cpool_count_plus_one; i++) {
if ( ci->cpool[i].ptr != NULL ) {
deallocate(ci, (void*)(ci->cpool[i].ptr));
ci->cpool[i].ptr = NULL;
}
}
deallocate(ci, (void*)ci->cpool);
ci->cpool = NULL;
}
}
static jboolean
skip_class(unsigned access_flags)
{
if ( access_flags & JVM_ACC_INTERFACE ) {
return JNI_TRUE;
}
return JNI_FALSE;
}
static long
inject_class(struct CrwClassImage *ci,
int system_class,
char* tclass_name,
char* tclass_sig,
char* call_name,
char* call_sig,
char* return_name,
char* return_sig,
char* obj_init_name,
char* obj_init_sig,
char* newarray_name,
char* newarray_sig,
unsigned char *buf,
long buf_len)
{
CrwConstantPoolEntry cs;
CrwCpoolIndex this_class;
CrwCpoolIndex super_class;
unsigned magic;
unsigned classfileMajorVersion;
unsigned classfileMinorVersion;
unsigned interface_count;
CRW_ASSERT_CI(ci);
CRW_ASSERT(ci, buf!=NULL);
CRW_ASSERT(ci, buf_len!=0);
CRW_ASSERT(ci, strchr(tclass_name,'.')==NULL); /* internal qualified name */
ci->injection_count = 0;
ci->system_class = system_class;
ci->tclass_name = tclass_name;
ci->tclass_sig = tclass_sig;
ci->call_name = call_name;
ci->call_sig = call_sig;
ci->return_name = return_name;
ci->return_sig = return_sig;
ci->obj_init_name = obj_init_name;
ci->obj_init_sig = obj_init_sig;
ci->newarray_name = newarray_name;
ci->newarray_sig = newarray_sig;
ci->output = buf;
ci->output_len = buf_len;
magic = copyU4(ci);
CRW_ASSERT(ci, magic==0xCAFEBABE);
if ( magic != 0xCAFEBABE ) {
return (long)0;
}
/* minor version number not used */
classfileMinorVersion = copyU2(ci);
/* major version number not used */
classfileMajorVersion = copyU2(ci);
CRW_ASSERT(ci, (classfileMajorVersion <= JVM_CLASSFILE_MAJOR_VERSION) ||
((classfileMajorVersion == JVM_CLASSFILE_MAJOR_VERSION) &&
(classfileMinorVersion <= JVM_CLASSFILE_MINOR_VERSION)));
cpool_setup(ci);
ci->access_flags = copyU2(ci);
if ( skip_class(ci->access_flags) ) {
return (long)0;
}
this_class = copyU2(ci);
cs = cpool_entry(ci, (CrwCpoolIndex)(cpool_entry(ci, this_class).index1));
if ( ci->name == NULL ) {
ci->name = duplicate(ci, cs.ptr, cs.len);
CRW_ASSERT(ci, strchr(ci->name,'.')==NULL); /* internal qualified name */
}
CRW_ASSERT(ci, (int)strlen(ci->name)==cs.len && strncmp(ci->name, cs.ptr, cs.len)==0);
super_class = copyU2(ci);
if ( super_class == 0 ) {
ci->is_object_class = JNI_TRUE;
CRW_ASSERT(ci, strcmp(ci->name,"java/lang/Object")==0);
}
interface_count = copyU2(ci);
copy(ci, interface_count * 2);
copy_all_fields(ci);
method_write_all(ci);
if ( ci->injection_count == 0 ) {
return (long)0;
}
copy_attributes(ci);
return (long)ci->output_position;
}
/* ------------------------------------------------------------------- */
/* Exported interfaces */
JNIEXPORT void JNICALL
java_crw_demo(unsigned class_number,
const char *name,
const unsigned char *file_image,
long file_len,
int system_class,
char* tclass_name, /* Name of class that has tracker methods. */
char* tclass_sig, /* Signature of tclass */
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 */
unsigned char **pnew_file_image,
long *pnew_file_len,
FatalErrorHandler fatal_error_handler,
MethodNumberRegister mnum_callback)
{
CrwClassImage ci;
long max_length;
long new_length;
void *new_image;
int len;
/* Initial setup of the CrwClassImage structure */
(void)memset(&ci, 0, (int)sizeof(CrwClassImage));
ci.fatal_error_handler = fatal_error_handler;
ci.mnum_callback = mnum_callback;
/* Do some interface error checks */
if ( pnew_file_image==NULL ) {
CRW_FATAL(&ci, "pnew_file_image==NULL");
}
if ( pnew_file_len==NULL ) {
CRW_FATAL(&ci, "pnew_file_len==NULL");
}
/* No file length means do nothing */
*pnew_file_image = NULL;
*pnew_file_len = 0;
if ( file_len==0 ) {
return;
}
/* Do some more interface error checks */
if ( file_image == NULL ) {
CRW_FATAL(&ci, "file_image == NULL");
}
if ( file_len < 0 ) {
CRW_FATAL(&ci, "file_len < 0");
}
if ( system_class != 0 && system_class != 1 ) {
CRW_FATAL(&ci, "system_class is not 0 or 1");
}
if ( tclass_name == NULL ) {
CRW_FATAL(&ci, "tclass_name == NULL");
}
if ( tclass_sig == NULL || tclass_sig[0]!='L' ) {
CRW_FATAL(&ci, "tclass_sig is not a valid class signature");
}
len = (int)strlen(tclass_sig);
if ( tclass_sig[len-1]!=';' ) {
CRW_FATAL(&ci, "tclass_sig is not a valid class signature");
}
if ( call_name != NULL ) {
if ( call_sig == NULL || strcmp(call_sig, "(II)V") != 0 ) {
CRW_FATAL(&ci, "call_sig is not (II)V");
}
}
if ( return_name != NULL ) {
if ( return_sig == NULL || strcmp(return_sig, "(II)V") != 0 ) {
CRW_FATAL(&ci, "return_sig is not (II)V");
}
}
if ( obj_init_name != NULL ) {
if ( obj_init_sig == NULL || strcmp(obj_init_sig, "(Ljava/lang/Object;)V") != 0 ) {
CRW_FATAL(&ci, "obj_init_sig is not (Ljava/lang/Object;)V");
}
}
if ( newarray_name != NULL ) {
if ( newarray_sig == NULL || strcmp(newarray_sig, "(Ljava/lang/Object;)V") != 0 ) {
CRW_FATAL(&ci, "newarray_sig is not (Ljava/lang/Object;)V");
}
}
/* Finish setup the CrwClassImage structure */
ci.is_thread_class = JNI_FALSE;
if ( name != NULL ) {
CRW_ASSERT(&ci, strchr(name,'.')==NULL); /* internal qualified name */
ci.name = duplicate(&ci, name, (int)strlen(name));
if ( strcmp(name, "java/lang/Thread")==0 ) {
ci.is_thread_class = JNI_TRUE;
}
}
ci.number = class_number;
ci.input = file_image;
ci.input_len = file_len;
/* Do the injection */
max_length = file_len*2 + 512; /* Twice as big + 512 */
new_image = allocate(&ci, (int)max_length);
new_length = inject_class(&ci,
system_class,
tclass_name,
tclass_sig,
call_name,
call_sig,
return_name,
return_sig,
obj_init_name,
obj_init_sig,
newarray_name,
newarray_sig,
new_image,
max_length);
/* Dispose or shrink the space to be returned. */
if ( new_length == 0 ) {
deallocate(&ci, (void*)new_image);
new_image = NULL;
} else {
new_image = (void*)reallocate(&ci, (void*)new_image, (int)new_length);
}
/* Return the new class image */
*pnew_file_image = (unsigned char *)new_image;
*pnew_file_len = (long)new_length;
/* Cleanup before we leave. */
cleanup(&ci);
}
/* Return the classname for this class which is inside the classfile image. */
JNIEXPORT char * JNICALL
java_crw_demo_classname(const unsigned char *file_image, long file_len,
FatalErrorHandler fatal_error_handler)
{
CrwClassImage ci;
CrwConstantPoolEntry cs;
CrwCpoolIndex this_class;
unsigned magic;
char * name;
name = NULL;
if ( file_len==0 || file_image==NULL ) {
return name;
}
/* The only fields we need filled in are the image pointer and the error
* handler.
* By not adding an output buffer pointer, no output is created.
*/
(void)memset(&ci, 0, (int)sizeof(CrwClassImage));
ci.input = file_image;
ci.input_len = file_len;
ci.fatal_error_handler = fatal_error_handler;
/* Read out the bytes from the classfile image */
magic = readU4(&ci); /* magic number */
CRW_ASSERT(&ci, magic==0xCAFEBABE);
if ( magic != 0xCAFEBABE ) {
return name;
}
(void)readU2(&ci); /* minor version number */
(void)readU2(&ci); /* major version number */
/* Read in constant pool. Since no output setup, writes are NOP's */
cpool_setup(&ci);
(void)readU2(&ci); /* access flags */
this_class = readU2(&ci); /* 'this' class */
/* Get 'this' constant pool entry */
cs = cpool_entry(&ci, (CrwCpoolIndex)(cpool_entry(&ci, this_class).index1));
/* Duplicate the name */
name = (char *)duplicate(&ci, cs.ptr, cs.len);
/* Cleanup before we leave. */
cleanup(&ci);
/* Return malloc space */
return name;
}
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