java_crw_demo.c

一个小公司要求给写的很简单的任务管理系统。

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;