Annotation of OpenXM_contrib2/asir2000/gc/ptr_chck.c, Revision 1.4
1.1 noro 1: /*
2: * Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
3: *
4: * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
5: * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
6: *
7: * Permission is hereby granted to use or copy this program
8: * for any purpose, provided the above notices are retained on all copies.
9: * Permission to modify the code and to distribute modified code is granted,
10: * provided the above notices are retained, and a notice that the code was
11: * modified is included with the above copyright notice.
12: */
13:
1.2 noro 14: /*
15: * These are checking routines calls to which could be inserted by a
16: * preprocessor to validate C pointer arithmetic.
17: */
18:
19: #include "private/gc_pmark.h"
1.1 noro 20:
21: #ifdef __STDC__
22: void GC_default_same_obj_print_proc(GC_PTR p, GC_PTR q)
23: #else
24: void GC_default_same_obj_print_proc (p, q)
25: GC_PTR p, q;
26: #endif
27: {
28: GC_err_printf2("0x%lx and 0x%lx are not in the same object\n",
29: (unsigned long)p, (unsigned long)q);
30: ABORT("GC_same_obj test failed");
31: }
32:
33: void (*GC_same_obj_print_proc) GC_PROTO((GC_PTR, GC_PTR))
34: = GC_default_same_obj_print_proc;
35:
36: /* Check that p and q point to the same object. Call */
37: /* *GC_same_obj_print_proc if they don't. */
38: /* Returns the first argument. (Return value may be hard */
39: /* to use,due to typing issues. But if we had a suitable */
40: /* preprocessor ...) */
41: /* Succeeds if neither p nor q points to the heap. */
42: /* We assume this is performance critical. (It shouldn't */
43: /* be called by production code, but this can easily make */
44: /* debugging intolerably slow.) */
45: #ifdef __STDC__
46: GC_PTR GC_same_obj(register void *p, register void *q)
47: #else
48: GC_PTR GC_same_obj(p, q)
49: register char *p, *q;
50: #endif
51: {
52: register struct hblk *h;
53: register hdr *hhdr;
54: register ptr_t base, limit;
55: register word sz;
56:
57: if (!GC_is_initialized) GC_init();
58: hhdr = HDR((word)p);
59: if (hhdr == 0) {
60: if (divHBLKSZ((word)p) != divHBLKSZ((word)q)
61: && HDR((word)q) != 0) {
62: goto fail;
63: }
64: return(p);
65: }
66: /* If it's a pointer to the middle of a large object, move it */
67: /* to the beginning. */
68: if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
69: h = HBLKPTR(p) - (word)hhdr;
70: hhdr = HDR(h);
71: while (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
72: h = FORWARDED_ADDR(h, hhdr);
73: hhdr = HDR(h);
74: }
1.2 noro 75: limit = (ptr_t)((word *)h + hhdr -> hb_sz);
1.1 noro 76: if ((ptr_t)p >= limit || (ptr_t)q >= limit || (ptr_t)q < (ptr_t)h ) {
77: goto fail;
78: }
79: return(p);
80: }
81: sz = WORDS_TO_BYTES(hhdr -> hb_sz);
82: if (sz > WORDS_TO_BYTES(MAXOBJSZ)) {
83: base = (ptr_t)HBLKPTR(p);
84: limit = base + sz;
85: if ((ptr_t)p >= limit) {
86: goto fail;
87: }
88: } else {
1.2 noro 89: register int map_entry;
90: register int pdispl = HBLKDISPL(p);
91:
92: map_entry = MAP_ENTRY((hhdr -> hb_map), pdispl);
93: if (map_entry > CPP_MAX_OFFSET) {
94: map_entry = BYTES_TO_WORDS(pdispl) % BYTES_TO_WORDS(sz);
95: if (HBLKPTR(p) != HBLKPTR(q)) goto fail;
96: /* W/o this check, we might miss an error if */
97: /* q points to the first object on a page, and */
98: /* points just before the page. */
99: }
100: base = (char *)((word)p & ~(WORDS_TO_BYTES(1) - 1));
101: base -= WORDS_TO_BYTES(map_entry);
1.1 noro 102: limit = base + sz;
103: }
104: /* [base, limit) delimits the object containing p, if any. */
105: /* If p is not inside a valid object, then either q is */
106: /* also outside any valid object, or it is outside */
107: /* [base, limit). */
108: if ((ptr_t)q >= limit || (ptr_t)q < base) {
109: goto fail;
110: }
111: return(p);
112: fail:
113: (*GC_same_obj_print_proc)((ptr_t)p, (ptr_t)q);
114: return(p);
115: }
116:
117: #ifdef __STDC__
118: void GC_default_is_valid_displacement_print_proc (GC_PTR p)
119: #else
120: void GC_default_is_valid_displacement_print_proc (p)
121: GC_PTR p;
122: #endif
123: {
124: GC_err_printf1("0x%lx does not point to valid object displacement\n",
125: (unsigned long)p);
126: ABORT("GC_is_valid_displacement test failed");
127: }
128:
129: void (*GC_is_valid_displacement_print_proc) GC_PROTO((GC_PTR)) =
130: GC_default_is_valid_displacement_print_proc;
131:
132: /* Check that if p is a pointer to a heap page, then it points to */
133: /* a valid displacement within a heap object. */
1.2 noro 134: /* Uninteresting with GC_all_interior_pointers. */
1.1 noro 135: /* Always returns its argument. */
136: /* Note that we don't lock, since nothing relevant about the header */
137: /* should change while we have a valid object pointer to the block. */
138: #ifdef __STDC__
139: void * GC_is_valid_displacement(void *p)
140: #else
141: char *GC_is_valid_displacement(p)
142: char *p;
143: #endif
144: {
145: register hdr *hhdr;
146: register word pdispl;
147: register struct hblk *h;
148: register map_entry_type map_entry;
149: register word sz;
150:
151: if (!GC_is_initialized) GC_init();
152: hhdr = HDR((word)p);
153: if (hhdr == 0) return(p);
154: h = HBLKPTR(p);
1.2 noro 155: if (GC_all_interior_pointers) {
1.1 noro 156: while (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
157: h = FORWARDED_ADDR(h, hhdr);
158: hhdr = HDR(h);
159: }
1.2 noro 160: }
1.1 noro 161: if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
162: goto fail;
163: }
164: sz = WORDS_TO_BYTES(hhdr -> hb_sz);
165: pdispl = HBLKDISPL(p);
166: map_entry = MAP_ENTRY((hhdr -> hb_map), pdispl);
167: if (map_entry == OBJ_INVALID
168: || sz > MAXOBJSZ && (ptr_t)p >= (ptr_t)h + sz) {
169: goto fail;
170: }
171: return(p);
172: fail:
173: (*GC_is_valid_displacement_print_proc)((ptr_t)p);
174: return(p);
175: }
176:
177: #ifdef __STDC__
178: void GC_default_is_visible_print_proc(GC_PTR p)
179: #else
180: void GC_default_is_visible_print_proc(p)
181: GC_PTR p;
182: #endif
183: {
184: GC_err_printf1("0x%lx is not a GC visible pointer location\n",
185: (unsigned long)p);
186: ABORT("GC_is_visible test failed");
187: }
188:
189: void (*GC_is_visible_print_proc) GC_PROTO((GC_PTR p)) =
190: GC_default_is_visible_print_proc;
191:
192: /* Could p be a stack address? */
193: GC_bool GC_on_stack(p)
194: ptr_t p;
195: {
196: # ifdef THREADS
197: return(TRUE);
198: # else
199: int dummy;
200: # ifdef STACK_GROWS_DOWN
201: if ((ptr_t)p >= (ptr_t)(&dummy) && (ptr_t)p < GC_stackbottom ) {
202: return(TRUE);
203: }
204: # else
205: if ((ptr_t)p <= (ptr_t)(&dummy) && (ptr_t)p > GC_stackbottom ) {
206: return(TRUE);
207: }
208: # endif
209: return(FALSE);
210: # endif
211: }
212:
213: /* Check that p is visible */
214: /* to the collector as a possibly pointer containing location. */
215: /* If it isn't invoke *GC_is_visible_print_proc. */
216: /* Returns the argument in all cases. May erroneously succeed */
217: /* in hard cases. (This is intended for debugging use with */
218: /* untyped allocations. The idea is that it should be possible, though */
219: /* slow, to add such a call to all indirect pointer stores.) */
220: /* Currently useless for multithreaded worlds. */
221: #ifdef __STDC__
222: void * GC_is_visible(void *p)
223: #else
224: char *GC_is_visible(p)
225: char *p;
226: #endif
227: {
228: register hdr *hhdr;
229:
230: if ((word)p & (ALIGNMENT - 1)) goto fail;
231: if (!GC_is_initialized) GC_init();
232: # ifdef THREADS
233: hhdr = HDR((word)p);
234: if (hhdr != 0 && GC_base(p) == 0) {
235: goto fail;
236: } else {
237: /* May be inside thread stack. We can't do much. */
238: return(p);
239: }
240: # else
241: /* Check stack first: */
242: if (GC_on_stack(p)) return(p);
243: hhdr = HDR((word)p);
244: if (hhdr == 0) {
245: GC_bool result;
246:
247: if (GC_is_static_root(p)) return(p);
248: /* Else do it again correctly: */
1.2 noro 249: # if (defined(DYNAMIC_LOADING) || defined(MSWIN32) || \
250: defined(MSWINCE) || defined(PCR)) \
1.1 noro 251: && !defined(SRC_M3)
252: DISABLE_SIGNALS();
253: GC_register_dynamic_libraries();
254: result = GC_is_static_root(p);
255: ENABLE_SIGNALS();
256: if (result) return(p);
257: # endif
258: goto fail;
259: } else {
260: /* p points to the heap. */
261: word descr;
262: ptr_t base = GC_base(p); /* Should be manually inlined? */
263:
264: if (base == 0) goto fail;
265: if (HBLKPTR(base) != HBLKPTR(p)) hhdr = HDR((word)p);
266: descr = hhdr -> hb_descr;
267: retry:
1.2 noro 268: switch(descr & GC_DS_TAGS) {
269: case GC_DS_LENGTH:
1.1 noro 270: if ((word)((ptr_t)p - (ptr_t)base) > (word)descr) goto fail;
271: break;
1.2 noro 272: case GC_DS_BITMAP:
1.1 noro 273: if ((ptr_t)p - (ptr_t)base
274: >= WORDS_TO_BYTES(BITMAP_BITS)
275: || ((word)p & (sizeof(word) - 1))) goto fail;
276: if (!((1 << (WORDSZ - ((ptr_t)p - (ptr_t)base) - 1))
277: & descr)) goto fail;
278: break;
1.2 noro 279: case GC_DS_PROC:
1.1 noro 280: /* We could try to decipher this partially. */
281: /* For now we just punt. */
282: break;
1.2 noro 283: case GC_DS_PER_OBJECT:
284: if ((signed_word)descr >= 0) {
285: descr = *(word *)((ptr_t)base + (descr & ~GC_DS_TAGS));
286: } else {
287: ptr_t type_descr = *(ptr_t *)base;
288: descr = *(word *)(type_descr
289: - (descr - (GC_DS_PER_OBJECT
290: - GC_INDIR_PER_OBJ_BIAS)));
291: }
1.1 noro 292: goto retry;
293: }
294: return(p);
295: }
296: # endif
297: fail:
298: (*GC_is_visible_print_proc)((ptr_t)p);
299: return(p);
300: }
301:
302:
303: GC_PTR GC_pre_incr (p, how_much)
304: GC_PTR *p;
305: size_t how_much;
306: {
307: GC_PTR initial = *p;
308: GC_PTR result = GC_same_obj((GC_PTR)((word)initial + how_much), initial);
309:
1.2 noro 310: if (!GC_all_interior_pointers) {
1.1 noro 311: (void) GC_is_valid_displacement(result);
1.2 noro 312: }
1.1 noro 313: return (*p = result);
314: }
315:
316: GC_PTR GC_post_incr (p, how_much)
317: GC_PTR *p;
318: size_t how_much;
319: {
320: GC_PTR initial = *p;
321: GC_PTR result = GC_same_obj((GC_PTR)((word)initial + how_much), initial);
322:
1.2 noro 323: if (!GC_all_interior_pointers) {
1.1 noro 324: (void) GC_is_valid_displacement(result);
1.2 noro 325: }
1.1 noro 326: *p = result;
327: return(initial);
328: }
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