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/* readclass.c -- parse and check structure of *.class files
* Written by Charles Briscoe-Smith; refer to the file LEGAL for details.
*/
/* Interface definitions */
/* Load in a class file, check the structure and return true if all is
okay. */
extern int readclass(const char filename[]);
#ifndef SEEN_readclass_h
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include "types.h"
static u1
readu1(FILE *fp)
{
return getc(fp);
}
static u2
readu2(FILE *fp)
{
int c1, c2;
c1=getc(fp);
c2=getc(fp);
return c1<<8 | c2;
}
static u4
readu4(FILE *fp)
{
int c1, c2, c3, c4;
c1=getc(fp);
c2=getc(fp);
c3=getc(fp);
c4=getc(fp);
return c1<<24 | c2<<16 | c3<<8 | c4;
}
#define error(str, a1) \
{ \
fprintf(stderr, "%s: Error: " str "\n", filename, a1); \
return 1; \
}
u2
readconst(FILE *fp, cp_info *buf)
{
int len;
int i;
u2 tag;
static int cont_flag=0;
static u4 cont_val;
if (cont_flag) {
cont_flag=0;
buf->u4=cont_val;
}
tag=readu1(fp);
switch (tag) {
case CONSTANT_Class:
case CONSTANT_String:
buf->u2=readu2(fp);
break;
case CONSTANT_Fieldref:
case CONSTANT_Methodref:
case CONSTANT_InterfaceMethodref:
case CONSTANT_NameAndType:
buf->u2x2.i1=readu2(fp);
buf->u2x2.i2=readu2(fp);
break;
case CONSTANT_Integer:
case CONSTANT_Float:
buf->u4=readu4(fp);
break;
case CONSTANT_Long:
case CONSTANT_Double:
buf->u4=readu4(fp);
cont_val=readu4(fp);
cont_flag=1;
break;
case CONSTANT_Utf8:
len=readu2(fp);
if (len>0) {
buf->utf8=(u1*) malloc(len+1);
buf->utf8[len]=0;
}
for (i=0; i<len; i++) {
buf->utf8[i]=readu1(fp);
}
break;
default:
fprintf(stderr, "invalid constant tag %d\n", tag);
}
return tag;
}
int
readclass(const char filename[])
{
FILE *fp;
u4 in4;
u2 minor, major;
u2 const_count, iface_count, field_count, meth_count, attr_count;
int i1;
cp_info *cp;
u2 access, this, super;
u2 *ifaces;
u2 *tag;
printf("\nClass file %s\n\n", filename);
fp=fopen(filename, "rb");
if (fp == 0) error("can't open: %s", strerror(errno));
in4=readu4(fp);
if (in4 != 0xCAFEBABE) error("invalid magic number 0x%08lX", in4);
printf("Magic: 0x%08lX\n", in4);
minor=readu2(fp);
major=readu2(fp);
if (major != 45) error("major version %d not supported", major);
printf("Major version: %d\n", major);
if (minor > 3) error("minor version %d not supported", minor);
printf("Minor version: %d\n", minor);
const_count=readu2(fp);
if (const_count == 0) error("constant count is %d", const_count);
printf("Number of constants: %d\n", const_count);
cp=(cp_info*) calloc(const_count, sizeof(cp_info));
tag=(u2*) calloc(const_count, sizeof(u2));
for (i1=1; i1<const_count; i1++) {
tag[i1]=readconst(fp, &cp[i1]);
if (tag[i1]==CONSTANT_Long
|| tag[i1]==CONSTANT_Double) {
i1++;
}
}
for (i1=0; i1<const_count; i1++) {
u4f u4f;
u8d u8d;
printf("Constant %d: ", i1);
if (i1==0) printf("reserved\n");
else if (tag[i1-1]==CONSTANT_Long
|| tag[i1-1]==CONSTANT_Double) printf("continuation word\n");
else switch (tag[i1]) {
case CONSTANT_Class:
printf("Class: %d (%s)\n", cp[i1].u2,
cp[cp[i1].u2].utf8);
break;
case CONSTANT_Fieldref:
printf("Fieldref: %d, %d (%s, %s, %s)\n",
cp[i1].u2x2.i1,
cp[i1].u2x2.i2,
cp[cp[cp[i1].u2x2.i1].u2].utf8,
cp[cp[cp[i1].u2x2.i2].u2x2.i1].utf8,
cp[cp[cp[i1].u2x2.i2].u2x2.i2].utf8);
break;
case CONSTANT_Methodref:
printf("Methodref: %d, %d (%s, %s, %s)\n",
cp[i1].u2x2.i1,
cp[i1].u2x2.i2,
cp[cp[cp[i1].u2x2.i1].u2].utf8,
cp[cp[cp[i1].u2x2.i2].u2x2.i1].utf8,
cp[cp[cp[i1].u2x2.i2].u2x2.i2].utf8);
break;
case CONSTANT_InterfaceMethodref:
printf("InterfaceMethodref: %d, %d (%s, %s, %s)\n",
cp[i1].u2x2.i1,
cp[i1].u2x2.i2,
cp[cp[cp[i1].u2x2.i1].u2].utf8,
cp[cp[cp[i1].u2x2.i2].u2x2.i1].utf8,
cp[cp[cp[i1].u2x2.i2].u2x2.i2].utf8);
break;
case CONSTANT_String:
printf("String: %d (\"%s\")\n", cp[i1].u2,
cp[cp[i1].u2].utf8);
break;
case CONSTANT_Integer:
printf("Integer: %ld\n", cp[i1].u4);
break;
case CONSTANT_Float:
u4f.u=cp[i1].u4;
printf("Float: %g\n", u4f.f);
break;
case CONSTANT_Long:
printf("Long: %qd\n", ((u8) cp[i1].u4 << 32) + cp[i1+1].u4);
break;
case CONSTANT_Double:
u8d.u=((u8) cp[i1].u4 << 32) + cp[i1+1].u4;
printf("Double: %g\n", u8d.d);
break;
case CONSTANT_NameAndType:
printf("NameAndType: %d, %d\n", cp[i1].u2x2.i1, cp[i1].u2x2.i2);
break;
case CONSTANT_Utf8:
printf("Utf8: \"%s\"\n", cp[i1].utf8);
break;
}
}
access=readu2(fp);
printf("Access flags:%s%s%s%s%s\n",
access & 0x0001 ? " public" : "",
access & 0x0010 ? " final" : "",
access & 0x0400 ? " abstract" : "",
access & 0x0200 ? " interface" : " class",
access & 0x0020 ? "" : " (without super flag; generated by old Sun compiler)");
this=readu2(fp);
printf("This class: %d\n", this);
super=readu2(fp);
printf("Superclass: %d\n", super);
iface_count=readu2(fp);
printf("Number of interfaces: %d:", iface_count);
ifaces=(u2*) calloc(iface_count, sizeof(u2));
for (i1=0; i1<iface_count; i1++) {
ifaces[i1]=readu2(fp);
printf(" %d", ifaces[i1]);
}
field_count=readu2(fp);
printf("\nNumber of fields: %d\n", field_count);
meth_count=readu2(fp);
printf("Number of methods: %d\n", meth_count);
attr_count=readu2(fp);
printf("Number of attributes: %d\n", attr_count);
if (feof(fp)) {
error("%s", "premature end of file");
}
return 0;
}
#endif /* SEEN_readclass_h */
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