ceph/src/boost/tools/build/src/engine/boehm_gc/ptr_chck.c

   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
  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"
  20
  21 void GC_default_same_obj_print_proc(void * p, void * q)
  22 {
  23     GC_err_printf("%p and %p are not in the same object\n", p, q);
  24     ABORT("GC_same_obj test failed");
  25 }
  26
  27 void (*GC_same_obj_print_proc) (void *, void *)
  28                 = GC_default_same_obj_print_proc;
  29
  30 /* Check that p and q point to the same object.  Call           */
  31 /* *GC_same_obj_print_proc if they don't.                       */
  32 /* Returns the first argument.  (Return value may be hard       */
  33 /* to use,due to typing issues.  But if we had a suitable       */
  34 /* preprocessor ...)                                            */
  35 /* Succeeds if neither p nor q points to the heap.              */
  36 /* We assume this is performance critical.  (It shouldn't       */
  37 /* be called by production code, but this can easily make       */
  38 /* debugging intolerably slow.)                                 */
  39 void * GC_same_obj(void *p, void *q)
  40 {
  41     struct hblk *h;
  42     hdr *hhdr;
  43     ptr_t base, limit;
  44     word sz;
  45
  46     if (!GC_is_initialized) GC_init();
  47     hhdr = HDR((word)p);
  48     if (hhdr == 0) {
  49         if (divHBLKSZ((word)p) != divHBLKSZ((word)q)
  50             && HDR((word)q) != 0) {
  51             goto fail;
  52         }
  53         return(p);
  54     }
  55     /* If it's a pointer to the middle of a large object, move it       */
  56     /* to the beginning.                                                */
  57     if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
  58         h = HBLKPTR(p) - (word)hhdr;
  59         hhdr = HDR(h);
  60         while (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
  61            h = FORWARDED_ADDR(h, hhdr);
  62            hhdr = HDR(h);
  63         }
  64         limit = (ptr_t)h + hhdr -> hb_sz;
  65         if ((ptr_t)p >= limit || (ptr_t)q >= limit || (ptr_t)q < (ptr_t)h ) {
  66             goto fail;
  67         }
  68         return(p);
  69     }
  70     sz = hhdr -> hb_sz;
  71     if (sz > MAXOBJBYTES) {
  72       base = (ptr_t)HBLKPTR(p);
  73       limit = base + sz;
  74       if ((ptr_t)p >= limit) {
  75         goto fail;
  76       }
  77     } else {
  78       size_t offset;
  79       size_t pdispl = HBLKDISPL(p);
  80
  81       offset = pdispl % sz;
  82       if (HBLKPTR(p) != HBLKPTR(q)) goto fail;
  83                 /* W/o this check, we might miss an error if    */
  84                 /* q points to the first object on a page, and  */
  85                 /* points just before the page.                 */
  86       base = (ptr_t)p - offset;
  87       limit = base + sz;
  88     }
  89     /* [base, limit) delimits the object containing p, if any.  */
  90     /* If p is not inside a valid object, then either q is      */
  91     /* also outside any valid object, or it is outside          */
  92     /* [base, limit).                                           */
  93     if ((ptr_t)q >= limit || (ptr_t)q < base) {
  94         goto fail;
  95     }
  96     return(p);
  97 fail:
  98     (*GC_same_obj_print_proc)((ptr_t)p, (ptr_t)q);
  99     return(p);
 100 }
 101
 102 void GC_default_is_valid_displacement_print_proc (void *p)
 103 {
 104     GC_err_printf("%p does not point to valid object displacement\n", p);
 105     ABORT("GC_is_valid_displacement test failed");
 106 }
 107
 108 void (*GC_is_valid_displacement_print_proc)(void *) =
 109         GC_default_is_valid_displacement_print_proc;
 110
 111 /* Check that if p is a pointer to a heap page, then it points to       */
 112 /* a valid displacement within a heap object.                           */
 113 /* Uninteresting with GC_all_interior_pointers.                         */
 114 /* Always returns its argument.                                         */
 115 /* Note that we don't lock, since nothing relevant about the header     */
 116 /* should change while we have a valid object pointer to the block.     */
 117 void * GC_is_valid_displacement(void *p)
 118 {
 119     hdr *hhdr;
 120     word pdispl;
 121     word offset;
 122     struct hblk *h;
 123     word sz;
 124
 125     if (!GC_is_initialized) GC_init();
 126     hhdr = HDR((word)p);
 127     if (hhdr == 0) return(p);
 128     h = HBLKPTR(p);
 129     if (GC_all_interior_pointers) {
 130         while (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
 131            h = FORWARDED_ADDR(h, hhdr);
 132            hhdr = HDR(h);
 133         }
 134     }
 135     if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
 136         goto fail;
 137     }
 138     sz = hhdr -> hb_sz;
 139     pdispl = HBLKDISPL(p);
 140     offset = pdispl % sz;
 141     if ((sz > MAXOBJBYTES && (ptr_t)p >= (ptr_t)h + sz)
 142         || !GC_valid_offsets[offset]
 143         || (ptr_t)p - offset + sz > (ptr_t)(h + 1)) {
 144         goto fail;
 145     }
 146     return(p);
 147 fail:
 148     (*GC_is_valid_displacement_print_proc)((ptr_t)p);
 149     return(p);
 150 }
 151
 152 void GC_default_is_visible_print_proc(void * p)
 153 {
 154     GC_err_printf("%p is not a GC visible pointer location\n", p);
 155     ABORT("GC_is_visible test failed");
 156 }
 157
 158 void (*GC_is_visible_print_proc)(void * p) = GC_default_is_visible_print_proc;
 159
 160 /* Could p be a stack address? */
 161 GC_bool GC_on_stack(ptr_t p)
 162 {
 163 #   ifdef THREADS
 164         return(TRUE);
 165 #   else
 166         int dummy;
 167 #       ifdef STACK_GROWS_DOWN
 168             if ((ptr_t)p >= (ptr_t)(&dummy) && (ptr_t)p < GC_stackbottom ) {
 169                 return(TRUE);
 170             }
 171 #       else
 172             if ((ptr_t)p <= (ptr_t)(&dummy) && (ptr_t)p > GC_stackbottom ) {
 173                 return(TRUE);
 174             }
 175 #       endif
 176         return(FALSE);
 177 #   endif
 178 }
 179
 180 /* Check that p is visible                                              */
 181 /* to the collector as a possibly pointer containing location.          */
 182 /* If it isn't invoke *GC_is_visible_print_proc.                        */
 183 /* Returns the argument in all cases.  May erroneously succeed          */
 184 /* in hard cases.  (This is intended for debugging use with             */
 185 /* untyped allocations.  The idea is that it should be possible, though */
 186 /* slow, to add such a call to all indirect pointer stores.)            */
 187 /* Currently useless for multithreaded worlds.                          */
 188 void * GC_is_visible(void *p)
 189 {
 190     hdr *hhdr;
 191
 192     if ((word)p & (ALIGNMENT - 1)) goto fail;
 193     if (!GC_is_initialized) GC_init();
 194 #   ifdef THREADS
 195         hhdr = HDR((word)p);
 196         if (hhdr != 0 && GC_base(p) == 0) {
 197             goto fail;
 198         } else {
 199             /* May be inside thread stack.  We can't do much. */
 200             return(p);
 201         }
 202 #   else
 203         /* Check stack first: */
 204           if (GC_on_stack(p)) return(p);
 205         hhdr = HDR((word)p);
 206         if (hhdr == 0) {
 207             GC_bool result;
 208
 209             if (GC_is_static_root(p)) return(p);
 210             /* Else do it again correctly:      */
 211 #           if (defined(DYNAMIC_LOADING) || defined(MSWIN32) || \
 212                 defined(MSWINCE) || defined(PCR))
 213                 GC_register_dynamic_libraries();
 214                 result = GC_is_static_root(p);
 215                 if (result) return(p);
 216 #           endif
 217             goto fail;
 218         } else {
 219             /* p points to the heap. */
 220             word descr;
 221             ptr_t base = GC_base(p);    /* Should be manually inlined? */
 222
 223             if (base == 0) goto fail;
 224             if (HBLKPTR(base) != HBLKPTR(p)) hhdr = HDR((word)p);
 225             descr = hhdr -> hb_descr;
 226     retry:
 227             switch(descr & GC_DS_TAGS) {
 228                 case GC_DS_LENGTH:
 229                     if ((word)((ptr_t)p - (ptr_t)base) > (word)descr) goto fail;
 230                     break;
 231                 case GC_DS_BITMAP:
 232                     if ((ptr_t)p - (ptr_t)base
 233                          >= WORDS_TO_BYTES(BITMAP_BITS)
 234                          || ((word)p & (sizeof(word) - 1))) goto fail;
 235                     if (!((1 << (WORDSZ - ((ptr_t)p - (ptr_t)base) - 1))
 236                           & descr)) goto fail;
 237                     break;
 238                 case GC_DS_PROC:
 239                     /* We could try to decipher this partially.         */
 240                     /* For now we just punt.                            */
 241                     break;
 242                 case GC_DS_PER_OBJECT:
 243                     if ((signed_word)descr >= 0) {
 244                       descr = *(word *)((ptr_t)base + (descr & ~GC_DS_TAGS));
 245                     } else {
 246                       ptr_t type_descr = *(ptr_t *)base;
 247                       descr = *(word *)(type_descr
 248                               - (descr - (GC_DS_PER_OBJECT
 249                                           - GC_INDIR_PER_OBJ_BIAS)));
 250                     }
 251                     goto retry;
 252             }
 253             return(p);
 254         }
 255 #   endif
 256 fail:
 257     (*GC_is_visible_print_proc)((ptr_t)p);
 258     return(p);
 259 }
 260
 261
 262 void * GC_pre_incr (void **p, size_t how_much)
 263 {
 264     void * initial = *p;
 265     void * result = GC_same_obj((void *)((word)initial + how_much), initial);
 266
 267     if (!GC_all_interior_pointers) {
 268         (void) GC_is_valid_displacement(result);
 269     }
 270     return (*p = result);
 271 }
 272
 273 void * GC_post_incr (void **p, size_t how_much)
 274 {
 275     void * initial = *p;
 276     void * result = GC_same_obj((void *)((word)initial + how_much), initial);
 277
 278     if (!GC_all_interior_pointers) {
 279         (void) GC_is_valid_displacement(result);
 280     }
 281     *p = result;
 282     return(initial);
 283 }