--- /dev/null
+/*
+ * 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.
+ */
+
+#include "private/gc_pmark.h"
+
+/*
+ * These are checking routines calls to which could be inserted by a
+ * preprocessor to validate C pointer arithmetic.
+ */
+
+STATIC void GC_CALLBACK GC_default_same_obj_print_proc(void * p, void * q)
+{
+ GC_err_printf("%p and %p are not in the same object\n", p, q);
+ ABORT("GC_same_obj test failed");
+}
+
+void (GC_CALLBACK *GC_same_obj_print_proc) (void *, void *)
+ = 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.) */
+GC_API void * GC_CALL GC_same_obj(void *p, void *q)
+{
+ struct hblk *h;
+ hdr *hhdr;
+ ptr_t base, limit;
+ 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)h + hhdr -> hb_sz;
+ if ((ptr_t)p >= limit || (ptr_t)q >= limit || (ptr_t)q < (ptr_t)h ) {
+ goto fail;
+ }
+ return(p);
+ }
+ sz = hhdr -> hb_sz;
+ if (sz > MAXOBJBYTES) {
+ base = (ptr_t)HBLKPTR(p);
+ limit = base + sz;
+ if ((ptr_t)p >= limit) {
+ goto fail;
+ }
+ } else {
+ size_t offset;
+ size_t pdispl = HBLKDISPL(p);
+
+ offset = pdispl % 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 = (ptr_t)p - offset;
+ 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);
+}
+
+STATIC void GC_CALLBACK GC_default_is_valid_displacement_print_proc (void *p)
+{
+ GC_err_printf("%p does not point to valid object displacement\n", p);
+ ABORT("GC_is_valid_displacement test failed");
+}
+
+void (GC_CALLBACK *GC_is_valid_displacement_print_proc)(void *) =
+ 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. */
+GC_API void * GC_CALL GC_is_valid_displacement(void *p)
+{
+ hdr *hhdr;
+ word pdispl;
+ word offset;
+ struct hblk *h;
+ 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 = hhdr -> hb_sz;
+ pdispl = HBLKDISPL(p);
+ offset = pdispl % sz;
+ if ((sz > MAXOBJBYTES && (ptr_t)p >= (ptr_t)h + sz)
+ || !GC_valid_offsets[offset]
+ || (ptr_t)p - offset + sz > (ptr_t)(h + 1)) {
+ goto fail;
+ }
+ return(p);
+fail:
+ (*GC_is_valid_displacement_print_proc)((ptr_t)p);
+ return(p);
+}
+
+STATIC void GC_CALLBACK GC_default_is_visible_print_proc(void * p)
+{
+ GC_err_printf("%p is not a GC visible pointer location\n", p);
+ ABORT("GC_is_visible test failed");
+}
+
+void (GC_CALLBACK *GC_is_visible_print_proc)(void * p) =
+ GC_default_is_visible_print_proc;
+
+#ifndef THREADS
+/* Could p be a stack address? */
+ STATIC GC_bool GC_on_stack(ptr_t p)
+ {
+# ifdef STACK_GROWS_DOWN
+ if ((ptr_t)p >= GC_approx_sp() && (ptr_t)p < GC_stackbottom) {
+ return(TRUE);
+ }
+# else
+ if ((ptr_t)p <= GC_approx_sp() && (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. */
+GC_API void * GC_CALL GC_is_visible(void *p)
+{
+ 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) {
+ if (GC_is_static_root(p)) return(p);
+ /* Else do it again correctly: */
+# if defined(DYNAMIC_LOADING) || defined(MSWIN32) \
+ || defined(MSWINCE) || defined(CYGWIN32) || defined(PCR)
+ GC_register_dynamic_libraries();
+ if (GC_is_static_root(p))
+ 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 ((word)((ptr_t)p - (ptr_t)base)
+ >= WORDS_TO_BYTES(BITMAP_BITS)
+ || ((word)p & (sizeof(word) - 1))) goto fail;
+ if (!(((word)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 - (word)(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_API void * GC_CALL GC_pre_incr (void **p, ptrdiff_t how_much)
+{
+ void * initial = *p;
+ void * result = GC_same_obj((void *)((ptr_t)initial + how_much), initial);
+
+ if (!GC_all_interior_pointers) {
+ (void) GC_is_valid_displacement(result);
+ }
+ return (*p = result);
+}
+
+GC_API void * GC_CALL GC_post_incr (void **p, ptrdiff_t how_much)
+{
+ void * initial = *p;
+ void * result = GC_same_obj((void *)((ptr_t)initial + how_much), initial);
+
+ if (!GC_all_interior_pointers) {
+ (void) GC_is_valid_displacement(result);
+ }
+ *p = result;
+ return(initial);
+}
projects / hs-boehmgc.git / blobdiff