diff options
Diffstat (limited to 'gc/ptr_chck.c')
| -rw-r--r-- | gc/ptr_chck.c | 326 |
1 files changed, 326 insertions, 0 deletions
diff --git a/gc/ptr_chck.c b/gc/ptr_chck.c new file mode 100644 index 0000000..f3451ee --- /dev/null +++ b/gc/ptr_chck.c @@ -0,0 +1,326 @@ +/* + * 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. + */ +/* Boehm, September 19, 1995 1:26 pm PDT */ + +#include "gc_priv.h" +#include "gc_mark.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 + HDR_WORDS + 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 { +# ifdef ALL_INTERIOR_POINTERS + register map_entry_type map_entry; + register int pdispl; + + pdispl = HBLKDISPL(p); + map_entry = MAP_ENTRY((hhdr -> hb_map), pdispl); + if (map_entry == OBJ_INVALID) { + goto fail; + } else { + base = (char *)((word)p & ~(WORDS_TO_BYTES(1) - 1)); + base -= WORDS_TO_BYTES(map_entry); + } +# else + register int offset = HBLKDISPL(p) - HDR_BYTES; + register word correction = offset % sz; + + if (HBLKPTR(p) != HBLKPTR(q)) { + /* The following computation otherwise fails in this case */ + goto fail; + } + base = (ptr_t)p - correction; +# endif + 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 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); +# ifdef ALL_INTERIOR_POINTERS + while (IS_FORWARDING_ADDR_OR_NIL(hhdr)) { + h = FORWARDED_ADDR(h, hhdr); + hhdr = HDR(h); + } +# endif + 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(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 & DS_TAGS) { + case DS_LENGTH: + if ((word)((ptr_t)p - (ptr_t)base) > (word)descr) goto fail; + break; + case 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 DS_PROC: + /* We could try to decipher this partially. */ + /* For now we just punt. */ + break; + case DS_PER_OBJECT: + descr = *(word *)((ptr_t)base + (descr & ~DS_TAGS)); + 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); + +# ifndef ALL_INTERIOR_POINTERS + (void) GC_is_valid_displacement(result); +# endif + 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); + +# ifndef ALL_INTERIOR_POINTERS + (void) GC_is_valid_displacement(result); +# endif + *p = result; + return(initial); +} |