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