// Verify the bytecode of one method m from class file cf
static void verifyMethod( ClassFile *cf, method_info *m ) {
char *name = GetCPItemAsString(cf, m->name_index);
char *retType;
int numSlots = m->max_locals + m->max_stack;
// initState is an array of strings, it has numSlots elements
// retType describes the result type of this method
char **initState = MapSigToInitState(cf, m, &retType);
if (tracingExecution & TRACE_VERIFY)
printTypeCodesArray(initState, m, name);
// Your code to verify the bytecode of the current method
// begins here.
// Feel free to define and use as many extra functions as
// are appropriate for this problem.
// Do include tracing output statements in your code
// controlled by the tracingExecution variable to help
// you debug the verification algorithm.
FreeTypeDescriptorArray(initState, numSlots);
SafeFree(name);
}
// Given the immediate operand of a getfield or putfield instruction (which
// is an index into the constant pool), this function returns a string which
// represents the datatype of that field.
char *FieldTypeCode( ClassFile *cf, int ix ) {
char *result = "";
char *s = GetCPItemAsString(cf, ix);
char *rp = strrchr(s, ':'); // find last occurrence of ':'
assert(rp != NULL);
ExtractOneType(&result, rp+1);
SafeFree(s);
return result;
}
void PrintByteCode( ClassFile *cf, uint8_t *code, int len ) {
int ix = 0;
while(ix < len) {
int opcodeAddr = ix;
uint8_t op = code[ix++];
char *opname = OPCodeFormat[op].name;
char *fmt = OPCodeFormat[op].opnds_format;
printf(" %3d: %s", opcodeAddr, opname);
if (fmt != NULL) {
int opndCnt = 0;
int dest, low, high, npairs;
int cpref = 0;
char *cptype = NULL;
while(*fmt != '\0') {
char f = *fmt++;
if (f != '0') {
if (opndCnt++ > 0) putchar(',');
putchar(' ');
}
switch(f) {
case 'v': /* one byte index to a local variable */
printf(" %d", code[ix++]);
break;
case 'T': /* type (class/array/interface) ref,
as a two byte index into the constant pool */
cpref = uget2(code,ix);
cptype = "Type";
printf(" #%d", cpref);
ix += 2;
break;
case 'C': /* class ref, as a two byte index into the constant pool */
cpref = uget2(code,ix);
cptype = "Class";
printf(" #%d", cpref);
ix += 2;
break;
case 'u': /* one byte unsigned immediate integer */
printf(" %d", code[ix]);
ix++;
break;
case 's': /* one byte signed immediate integer */
printf(" %d", (signed char)code[ix]);
ix++;
break;
case 'F': /* field ref, as a two byte index into the constant pool */
cpref = uget2(code,ix);
cptype = "Field";
printf(" #%d", cpref);
ix += 2;
break;
case 'I': /* interface ref, as a two byte index into the constant pool */
cpref = uget2(code,ix);
cptype = "Interface";
printf(" #%d", cpref);
ix += 2;
break;
case 'b': /* two byte branch destination */
dest = opcodeAddr + iget2(code,ix);
printf(" %d", dest);
ix += 2;
break;
case 'B': /* four byte branch destination */
printf(" %d", (int)(opcodeAddr + iget4(code,ix)));
ix += 4;
break;
case 'M': /* method ref, as a two byte index into the constant pool */
cpref = uget2(code,ix);
cptype = "Method";
printf(" #%d", cpref);
ix += 2;
break;
case 'k': /* simple constant in constant pool, one byte index */
cpref = code[ix];
cptype = " ";
printf(" #%d", cpref);
ix++;
break;
case 'K': /* simple constant in constant pool, two byte index */
cpref = uget2(code,ix);
cptype = " ";
printf(" #%d", cpref);
ix += 2;
break;
case 'a': /* one byte primitive type */
dest = code[ix] & 0xff;
if (dest >= 12) dest = 0;
printf(" %s", basicType[dest]);
ix++;
break;
case 'S': /* two byte signed immediate integer */
printf(" %d", iget2(code,ix));
ix += 2;
break;
case '*': /* lookupswitch */
ix = (ix + 3) & 0xFFFFFFFC; /* skip over padding bytes */
printf("\n default: %d\n",
(int)(opcodeAddr + iget4(code,ix)));
ix += 4;
npairs = iget4(code,ix); ix += 4;
while(npairs-- > 0) {
printf(" case %d:", iget4(code,ix)); ix += 4;
printf(" %d\n", opcodeAddr + iget4(code,ix)); ix += 4;
}
break;
case '&': /* tableswitch */
ix = (ix + 3) & 0xFFFFFFFC; /* skip over padding bytes */
printf("\n default: %d\n",
opcodeAddr + iget4(code,ix));
ix += 4;
low = iget4(code,ix); ix += 4;
high = iget4(code,ix); ix += 4;
while(low <= high) {
printf(" case %d:", low++);
printf(" %d\n", opcodeAddr + iget4(code,ix)); ix += 4;
}
break;
case 'w': /* wide */
op = code[ix++]; /* the op being modified by wide */
printf("-%s %d", OPCodeFormat[op].name, uget2(code,ix));
ix += 2;
if (op == 0x84) { /* iinc -- Format 2 */
printf(", %d", iget2(code,ix));
ix += 2;
}
break;
case '0': /* a zero byte */
ix++;
break;
default:
fprintf(stderr, "bad operand format code; op=%s, code=%c\n",
opname, fmt[-1]);
printf(" ???\n");
return;
}
}
if (cptype != NULL)
printf("; //%s %s", cptype, GetCPItemAsString(cf, cpref));
}
putchar('\n');
}
}
