/*
* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose, provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*/
/*
* These are checking routines calls to which could be inserted by a
* preprocessor to validate C pointer arithmetic.
*/
#include "private/gc_pmark.h"
#ifdef __STDC__
void GC_default_same_obj_print_proc(GC_PTR p, GC_PTR q)
#else
void GC_default_same_obj_print_proc (p, q)
GC_PTR p, q;
#endif
{
GC_err_printf2("0x%lx and 0x%lx are not in the same object\n",
(unsigned long)p, (unsigned long)q);
ABORT("GC_same_obj test failed");
}
void (*GC_same_obj_print_proc) GC_PROTO((GC_PTR, GC_PTR))
= GC_default_same_obj_print_proc;
/* Check that p and q point to the same object. Call */
/* *GC_same_obj_print_proc if they don't. */
/* Returns the first argument. (Return value may be hard */
/* to use,due to typing issues. But if we had a suitable */
/* preprocessor ...) */
/* Succeeds if neither p nor q points to the heap. */
/* We assume this is performance critical. (It shouldn't */
/* be called by production code, but this can easily make */
/* debugging intolerably slow.) */
#ifdef __STDC__
GC_PTR GC_same_obj(register void *p, register void *q)
#else
GC_PTR GC_same_obj(p, q)
register char *p, *q;
#endif
{
register struct hblk *h;
register hdr *hhdr;
register ptr_t base, limit;
register word sz;
if (!GC_is_initialized) GC_init();
hhdr = HDR((word)p);
if (hhdr == 0) {
if (divHBLKSZ((word)p) != divHBLKSZ((word)q)
&& HDR((word)q) != 0) {
goto fail;
}
return(p);
}
/* If it's a pointer to the middle of a large object, move it */
/* to the beginning. */
if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
h = HBLKPTR(p) - (word)hhdr;
hhdr = HDR(h);
while (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
h = FORWARDED_ADDR(h, hhdr);
hhdr = HDR(h);
}
limit = (ptr_t)((word *)h + hhdr -> hb_sz);
if ((ptr_t)p >= limit || (ptr_t)q >= limit || (ptr_t)q < (ptr_t)h ) {
goto fail;
}
return(p);
}
sz = WORDS_TO_BYTES(hhdr -> hb_sz);
if (sz > WORDS_TO_BYTES(MAXOBJSZ)) {
base = (ptr_t)HBLKPTR(p);
limit = base + sz;
if ((ptr_t)p >= limit) {
goto fail;
}
} else {
register int map_entry;
register int pdispl = HBLKDISPL(p);
map_entry = MAP_ENTRY((hhdr -> hb_map), pdispl);
if (map_entry > CPP_MAX_OFFSET) {
map_entry = BYTES_TO_WORDS(pdispl) % BYTES_TO_WORDS(sz);
if (HBLKPTR(p) != HBLKPTR(q)) goto fail;
/* W/o this check, we might miss an error if */
/* q points to the first object on a page, and */
/* points just before the page. */
}
base = (char *)((word)p & ~(WORDS_TO_BYTES(1) - 1));
base -= WORDS_TO_BYTES(map_entry);
limit = base + sz;
}
/* [base, limit) delimits the object containing p, if any. */
/* If p is not inside a valid object, then either q is */
/* also outside any valid object, or it is outside */
/* [base, limit). */
if ((ptr_t)q >= limit || (ptr_t)q < base) {
goto fail;
}
return(p);
fail:
(*GC_same_obj_print_proc)((ptr_t)p, (ptr_t)q);
return(p);
}
#ifdef __STDC__
void GC_default_is_valid_displacement_print_proc (GC_PTR p)
#else
void GC_default_is_valid_displacement_print_proc (p)
GC_PTR p;
#endif
{
GC_err_printf1("0x%lx does not point to valid object displacement\n",
(unsigned long)p);
ABORT("GC_is_valid_displacement test failed");
}
void (*GC_is_valid_displacement_print_proc) GC_PROTO((GC_PTR)) =
GC_default_is_valid_displacement_print_proc;
/* Check that if p is a pointer to a heap page, then it points to */
/* a valid displacement within a heap object. */
/* Uninteresting with GC_all_interior_pointers. */
/* Always returns its argument. */
/* Note that we don't lock, since nothing relevant about the header */
/* should change while we have a valid object pointer to the block. */
#ifdef __STDC__
void * GC_is_valid_displacement(void *p)
#else
char *GC_is_valid_displacement(p)
char *p;
#endif
{
register hdr *hhdr;
register word pdispl;
register struct hblk *h;
register map_entry_type map_entry;
register word sz;
if (!GC_is_initialized) GC_init();
hhdr = HDR((word)p);
if (hhdr == 0) return(p);
h = HBLKPTR(p);
if (GC_all_interior_pointers) {
while (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
h = FORWARDED_ADDR(h, hhdr);
hhdr = HDR(h);
}
}
if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
goto fail;
}
sz = WORDS_TO_BYTES(hhdr -> hb_sz);
pdispl = HBLKDISPL(p);
map_entry = MAP_ENTRY((hhdr -> hb_map), pdispl);
if (map_entry == OBJ_INVALID
|| sz > MAXOBJSZ && (ptr_t)p >= (ptr_t)h + sz) {
goto fail;
}
return(p);
fail:
(*GC_is_valid_displacement_print_proc)((ptr_t)p);
return(p);
}
#ifdef __STDC__
void GC_default_is_visible_print_proc(GC_PTR p)
#else
void GC_default_is_visible_print_proc(p)
GC_PTR p;
#endif
{
GC_err_printf1("0x%lx is not a GC visible pointer location\n",
(unsigned long)p);
ABORT("GC_is_visible test failed");
}
void (*GC_is_visible_print_proc) GC_PROTO((GC_PTR p)) =
GC_default_is_visible_print_proc;
/* Could p be a stack address? */
GC_bool GC_on_stack(p)
ptr_t p;
{
# ifdef THREADS
return(TRUE);
# else
int dummy;
# ifdef STACK_GROWS_DOWN
if ((ptr_t)p >= (ptr_t)(&dummy) && (ptr_t)p < GC_stackbottom ) {
return(TRUE);
}
# else
if ((ptr_t)p <= (ptr_t)(&dummy) && (ptr_t)p > GC_stackbottom ) {
return(TRUE);
}
# endif
return(FALSE);
# endif
}
/* Check that p is visible */
/* to the collector as a possibly pointer containing location. */
/* If it isn't invoke *GC_is_visible_print_proc. */
/* Returns the argument in all cases. May erroneously succeed */
/* in hard cases. (This is intended for debugging use with */
/* untyped allocations. The idea is that it should be possible, though */
/* slow, to add such a call to all indirect pointer stores.) */
/* Currently useless for multithreaded worlds. */
#ifdef __STDC__
void * GC_is_visible(void *p)
#else
char *GC_is_visible(p)
char *p;
#endif
{
register hdr *hhdr;
if ((word)p & (ALIGNMENT - 1)) goto fail;
if (!GC_is_initialized) GC_init();
# ifdef THREADS
hhdr = HDR((word)p);
if (hhdr != 0 && GC_base(p) == 0) {
goto fail;
} else {
/* May be inside thread stack. We can't do much. */
return(p);
}
# else
/* Check stack first: */
if (GC_on_stack(p)) return(p);
hhdr = HDR((word)p);
if (hhdr == 0) {
GC_bool result;
if (GC_is_static_root(p)) return(p);
/* Else do it again correctly: */
# if (defined(DYNAMIC_LOADING) || defined(MSWIN32) || \
defined(MSWINCE) || defined(PCR)) \
&& !defined(SRC_M3)
DISABLE_SIGNALS();
GC_register_dynamic_libraries();
result = GC_is_static_root(p);
ENABLE_SIGNALS();
if (result) return(p);
# endif
goto fail;
} else {
/* p points to the heap. */
word descr;
ptr_t base = GC_base(p); /* Should be manually inlined? */
if (base == 0) goto fail;
if (HBLKPTR(base) != HBLKPTR(p)) hhdr = HDR((word)p);
descr = hhdr -> hb_descr;
retry:
switch(descr & GC_DS_TAGS) {
case GC_DS_LENGTH:
if ((word)((ptr_t)p - (ptr_t)base) > (word)descr) goto fail;
break;
case GC_DS_BITMAP:
if ((ptr_t)p - (ptr_t)base
>= WORDS_TO_BYTES(BITMAP_BITS)
|| ((word)p & (sizeof(word) - 1))) goto fail;
if (!((1 << (WORDSZ - ((ptr_t)p - (ptr_t)base) - 1))
& descr)) goto fail;
break;
case GC_DS_PROC:
/* We could try to decipher this partially. */
/* For now we just punt. */
break;
case GC_DS_PER_OBJECT:
if ((signed_word)descr >= 0) {
descr = *(word *)((ptr_t)base + (descr & ~GC_DS_TAGS));
} else {
ptr_t type_descr = *(ptr_t *)base;
descr = *(word *)(type_descr
- (descr - (GC_DS_PER_OBJECT
- GC_INDIR_PER_OBJ_BIAS)));
}
goto retry;
}
return(p);
}
# endif
fail:
(*GC_is_visible_print_proc)((ptr_t)p);
return(p);
}
GC_PTR GC_pre_incr (p, how_much)
GC_PTR *p;
size_t how_much;
{
GC_PTR initial = *p;
GC_PTR result = GC_same_obj((GC_PTR)((word)initial + how_much), initial);
if (!GC_all_interior_pointers) {
(void) GC_is_valid_displacement(result);
}
return (*p = result);
}
GC_PTR GC_post_incr (p, how_much)
GC_PTR *p;
size_t how_much;
{
GC_PTR initial = *p;
GC_PTR result = GC_same_obj((GC_PTR)((word)initial + how_much), initial);
if (!GC_all_interior_pointers) {
(void) GC_is_valid_displacement(result);
}
*p = result;
return(initial);
}
