1 /* A toy re-implementation of CPython's object model. */
2
3 #include <stddef.h>
4 #include <string.h>
5 #include <stdlib.h>
6
7 typedef struct base_obj base_obj;
8 typedef struct type_obj type_obj;
9 typedef struct string_obj string_obj;
10
11 struct base_obj
12 {
13 struct type_obj *ob_type;
14 int ob_refcnt;
15 };
16
17 struct type_obj
18 {
19 base_obj tp_base;
20 void (*tp_dealloc) (base_obj *);
21 };
22
23 struct string_obj
24 {
25 base_obj str_base;
26 size_t str_len;
27 char str_buf[];
28 };
29
30 extern void type_del (base_obj *);
31 extern void str_del (base_obj *);
32
33 type_obj type_type = {
34 { &type_type, 1},
35 type_del
36 };
37
38 type_obj str_type = {
39 { &str_type, 1},
40 str_del
41 };
42
alloc_obj(type_obj * ob_type,size_t sz)43 base_obj *alloc_obj (type_obj *ob_type, size_t sz)
44 {
45 base_obj *obj = (base_obj *)malloc (sz);
46 if (!obj)
47 return NULL;
48 obj->ob_type = ob_type;
49 obj->ob_refcnt = 1;
50 return obj;
51 }
52
new_string_obj(const char * str)53 string_obj *new_string_obj (const char *str)
54 {
55 //__analyzer_dump ();
56 size_t len = strlen (str);
57 #if 1
58 string_obj *str_obj
59 = (string_obj *)alloc_obj (&str_type, sizeof (string_obj) + len + 1);
60 #else
61 string_obj *str_obj = (string_obj *)malloc (sizeof (string_obj) + len + 1);
62 if (!str_obj)
63 return NULL;
64 str_obj->str_base.ob_type = &str_type;
65 str_obj->str_base.ob_refcnt = 1;
66 #endif
67 str_obj->str_len = len; /* { dg-warning "dereference of NULL 'str_obj'" } */
68 memcpy (str_obj->str_buf, str, len);
69 str_obj->str_buf[len] = '\0';
70 return str_obj;
71 }
72
unref(string_obj * obj)73 void unref (string_obj *obj)
74 {
75 //__analyzer_dump();
76 if (--obj->str_base.ob_refcnt == 0)
77 {
78 //__analyzer_dump();
79 obj->str_base.ob_type->tp_dealloc ((base_obj *)obj);
80 }
81 }
82
test_1(const char * str)83 void test_1 (const char *str)
84 {
85 string_obj *obj = new_string_obj (str);
86 //__analyzer_dump();
87 if (obj)
88 unref (obj);
89 } /* { dg-bogus "leak of 'obj'" "" { xfail *-*-* } } */
90 /* TODO(xfail): the false leak report involves the base_obj.ob_refcnt
91 being 1, but the string_obj.str_base.ob_refcnt being unknown (when
92 they ought to be the same region), thus allowing for a path in which
93 the object is allocated but not freed. */
94