X-Git-Url: http://wien.tomnetworks.com/gitweb/?p=hs-boehmgc.git;a=blobdiff_plain;f=gc-7.2%2Fptr_chck.c;fp=gc-7.2%2Fptr_chck.c;h=b48feb2ed912eb61a004e04ce018030bbdfd7df6;hp=0000000000000000000000000000000000000000;hb=324587ba93dc77f37406d41fd2a20d0e0d94fb1d;hpb=2a4ea609491b225a1ceb06da70396e93916f137a

diff --git a/gc-7.2/ptr_chck.c b/gc-7.2/ptr_chck.c
new file mode 100644
index 0000000..b48feb2
--- /dev/null
+++ b/gc-7.2/ptr_chck.c
@@ -0,0 +1,278 @@
+/*
+ * 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);
+}