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Commit fecdde2

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authored
Merge pull request #7 from hankluo6/object_heap
Implement object heap
2 parents 3181bc7 + 54662e2 commit fecdde2

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12 files changed

+463
-57
lines changed

12 files changed

+463
-57
lines changed

‎Makefile‎

Lines changed: 5 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,8 @@ OBJS = \
77
stack.o \
88
constant-pool.o \
99
classfile.o \
10-
class-heap.o
10+
class-heap.o \
11+
object-heap.o
1112

1213
deps := $(OBJS:%.o=.%.o.d)
1314

@@ -43,8 +44,9 @@ TESTS = \
4344
Primes \
4445
Recursion \
4546
Long \
46-
Caller
47-
47+
Caller \
48+
Constructor
49+
4850
check: $(addprefix tests/,$(TESTS:=-result.out))
4951

5052
ifneq (, $(shell which valgrind))

‎class-heap.c‎

Lines changed: 47 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -35,6 +35,52 @@ class_file_t *find_class_from_heap(char *value)
3535
return NULL;
3636
}
3737

38+
class_file_t *find_or_add_class_to_heap(char *class_name, char *prefix)
39+
{
40+
class_file_t *target_class = find_class_from_heap(class_name);
41+
42+
/* if class is not found, adding specific class path and finding
43+
* again. This can be removed by recording path infomation in class
44+
* heap
45+
*/
46+
if (!target_class && prefix) {
47+
char *tmp = malloc(strlen(class_name) + strlen(prefix) + 1);
48+
strcpy(tmp, prefix);
49+
strcat(tmp, class_name);
50+
target_class = find_class_from_heap(tmp);
51+
52+
free(tmp);
53+
}
54+
55+
/* if class is still not found, meaning that this class is not
56+
* loaded in class heap, so add it to the class heap. */
57+
if (!target_class) {
58+
char *tmp;
59+
if (prefix) {
60+
tmp = malloc(
61+
(strlen(class_name) + strlen(".class") + strlen(prefix) + 1));
62+
strcpy(tmp, prefix);
63+
strcat(tmp, class_name);
64+
} else {
65+
tmp = malloc(strlen(class_name) + strlen(".class") + 1);
66+
strcpy(tmp, class_name);
67+
}
68+
/* attempt to read given class file */
69+
FILE *class_file = fopen(strcat(tmp, ".class"), "r");
70+
assert(class_file && "Failed to open file");
71+
72+
/* parse the class file */
73+
target_class = malloc(sizeof(class_file_t));
74+
*target_class = get_class(class_file);
75+
int error = fclose(class_file);
76+
assert(!error && "Failed to close file");
77+
add_class(target_class, tmp);
78+
free(tmp);
79+
}
80+
81+
return target_class;
82+
}
83+
3884
void free_class_heap()
3985
{
4086
for (int i = 0; i < class_heap.length; ++i) {
@@ -45,6 +91,7 @@ void free_class_heap()
4591
free(constant->info);
4692
}
4793
free(class_heap.class_info[i]->clazz->constant_pool.constant_pool);
94+
free(class_heap.class_info[i]->clazz->fields);
4895

4996
for (method_t *method = class_heap.class_info[i]->clazz->methods;
5097
method->name; method++) {

‎class-heap.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -11,6 +11,7 @@ void init_class_heap();
1111
void free_class_heap();
1212
void add_class(class_file_t *clazz, char *name);
1313
class_file_t *find_class_from_heap(char *value);
14+
class_file_t *find_or_add_class_to_heap(char *class_name, char *prefix);
1415
char *find_method_info_from_index(uint16_t idx,
1516
class_file_t *clazz,
1617
char **name_info,

‎classfile.c‎

Lines changed: 103 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -18,8 +18,6 @@ class_info_t get_class_info(FILE *class_file)
1818
};
1919
u2 interfaces_count = read_u2(class_file);
2020
assert(!interfaces_count && "This VM does not support interfaces.");
21-
u2 fields_count = read_u2(class_file);
22-
assert(!fields_count && "This VM does not support fields.");
2321
return info;
2422
}
2523

@@ -92,6 +90,75 @@ char *find_method_info_from_index(uint16_t idx,
9290
return (char *) class_name->info;
9391
}
9492

93+
CONSTANT_FieldOrMethodRef_info *get_fieldref(constant_pool_t *cp, u2 idx)
94+
{
95+
const_pool_info *field = get_constant(cp, idx);
96+
assert(field->tag == CONSTANT_FieldRef && "Expected a FieldRef");
97+
return (CONSTANT_FieldOrMethodRef_info *) field->info;
98+
}
99+
100+
/**
101+
* Find the field info corresponding to the given constant pool index.
102+
*
103+
* @param index the constant pool index of the Methodref to call
104+
* @param clazz the parsed class file
105+
* @param name_info the pointer that will contain method name on return
106+
* @param descriptor_info the pointer that will contain method infomation on
107+
* return
108+
* @return the class name which has this field
109+
*/
110+
char *find_field_info_from_index(uint16_t idx,
111+
class_file_t *clazz,
112+
char **name_info,
113+
char **descriptor_info)
114+
{
115+
CONSTANT_FieldOrMethodRef_info *field_ref =
116+
get_fieldref(&clazz->constant_pool, idx);
117+
const_pool_info *name_and_type =
118+
get_constant(&clazz->constant_pool, field_ref->name_and_type_index);
119+
assert(name_and_type->tag == CONSTANT_NameAndType &&
120+
"Expected a NameAndType");
121+
const_pool_info *name = get_constant(
122+
&clazz->constant_pool,
123+
((CONSTANT_NameAndType_info *) name_and_type->info)->name_index);
124+
assert(name->tag == CONSTANT_Utf8 && "Expected a UTF8");
125+
const_pool_info *descriptor = get_constant(
126+
&clazz->constant_pool,
127+
((CONSTANT_NameAndType_info *) name_and_type->info)->descriptor_index);
128+
assert(descriptor->tag == CONSTANT_Utf8 && "Expected a UTF8");
129+
CONSTANT_Class_info *class_info =
130+
get_class_name(&clazz->constant_pool, field_ref->class_index);
131+
const_pool_info *class_name =
132+
get_constant(&clazz->constant_pool, class_info->string_index);
133+
*name_info = (char *) name->info;
134+
*descriptor_info = (char *) descriptor->info;
135+
136+
return (char *) class_name->info;
137+
}
138+
139+
char *find_class_name_from_index(uint16_t idx, class_file_t *clazz)
140+
{
141+
CONSTANT_Class_info *class = get_class_name(&clazz->constant_pool, idx);
142+
143+
const_pool_info *name =
144+
get_constant(&clazz->constant_pool, class->string_index);
145+
assert(name->tag == CONSTANT_Utf8 && "Expected a UTF8");
146+
return (char *) name->info;
147+
}
148+
149+
void read_field_attributes(FILE *class_file, field_info *info)
150+
{
151+
for (u2 i = 0; i < info->attributes_count; i++) {
152+
attribute_info ainfo = {
153+
.attribute_name_index = read_u2(class_file),
154+
.attribute_length = read_u4(class_file),
155+
};
156+
long attribute_end = ftell(class_file) + ainfo.attribute_length;
157+
/* Skip all the attribute */
158+
fseek(class_file, attribute_end, SEEK_SET);
159+
}
160+
}
161+
95162
void read_method_attributes(FILE *class_file,
96163
method_info *info,
97164
code_t *code,
@@ -129,6 +196,37 @@ void read_method_attributes(FILE *class_file,
129196

130197
#define IS_STATIC 0x0008
131198

199+
field_t *get_fields(FILE *class_file, constant_pool_t *cp, class_file_t *clazz)
200+
{
201+
u2 fields_count = read_u2(class_file);
202+
clazz->fields_count = fields_count;
203+
field_t *fields = malloc(sizeof(*fields) * (fields_count + 1));
204+
assert(fields && "Failed to allocate methods");
205+
206+
field_t *field = fields;
207+
for (u2 i = 0; i < fields_count; i++, field++) {
208+
field_info info = {
209+
.access_flags = read_u2(class_file),
210+
.name_index = read_u2(class_file),
211+
.descriptor_index = read_u2(class_file),
212+
.attributes_count = read_u2(class_file),
213+
};
214+
215+
const_pool_info *name = get_constant(cp, info.name_index);
216+
assert(name->tag == CONSTANT_Utf8 && "Expected a UTF8");
217+
field->name = (char *) name->info;
218+
const_pool_info *descriptor = get_constant(cp, info.descriptor_index);
219+
assert(descriptor->tag == CONSTANT_Utf8 && "Expected a UTF8");
220+
field->descriptor = (char *) descriptor->info;
221+
222+
read_field_attributes(class_file, &info);
223+
}
224+
225+
/* Mark end of array with NULL name */
226+
field->name = NULL;
227+
return fields;
228+
}
229+
132230
method_t *get_methods(FILE *class_file, constant_pool_t *cp)
133231
{
134232
u2 method_count = read_u2(class_file);
@@ -184,6 +282,9 @@ class_file_t get_class(FILE *class_file)
184282
/* Read information about the class that was compiled. */
185283
get_class_info(class_file);
186284

285+
/* Read the list of fields */
286+
clazz.fields = get_fields(class_file, &clazz.constant_pool, &clazz);
287+
187288
/* Read the list of static methods */
188289
clazz.methods = get_methods(class_file, &clazz.constant_pool);
189290
return clazz;

‎classfile.h‎

Lines changed: 24 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -22,6 +22,13 @@ typedef struct {
2222
u2 attributes_count;
2323
} method_info;
2424

25+
typedef struct {
26+
u2 access_flags;
27+
u2 name_index;
28+
u2 descriptor_index;
29+
u2 attributes_count;
30+
} field_info;
31+
2532
typedef struct {
2633
u2 attribute_name_index;
2734
u4 attribute_length;
@@ -40,9 +47,17 @@ typedef struct {
4047
code_t code;
4148
} method_t;
4249

50+
typedef struct {
51+
char *class_name;
52+
char *name;
53+
char *descriptor;
54+
} field_t;
55+
4356
typedef struct {
4457
constant_pool_t constant_pool;
4558
method_t *methods;
59+
field_t *fields;
60+
u2 fields_count;
4661
} class_file_t;
4762

4863
typedef struct {
@@ -60,4 +75,12 @@ void read_method_attributes(FILE *class_file,
6075
uint16_t get_number_of_parameters(method_t *method);
6176
method_t *find_method(const char *name, const char *desc, class_file_t *clazz);
6277
method_t *find_method_from_index(uint16_t idx, class_file_t *clazz);
63-
class_file_t get_class(FILE *class_file);
78+
class_file_t get_class(FILE *class_file);
79+
char *find_class_name_from_index(uint16_t idx, class_file_t *clazz);
80+
CONSTANT_FieldOrMethodRef_info *get_fieldref(constant_pool_t *cp, u2 idx);
81+
char *find_field_info_from_index(uint16_t idx,
82+
class_file_t *clazz,
83+
char **name_info,
84+
char **descriptor_info);
85+
void read_field_attributes(FILE *class_file, field_info *info);
86+
field_t *get_fields(FILE *class_file, constant_pool_t *cp, class_file_t *clazz);

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