ghostscript-7.07/src/ilocate.c

/* Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000 artofcode LLC.  All rights reserved.

  This program is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by the
  Free Software Foundation; either version 2 of the License, or (at your
  option) any later version.

  This program is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License along
  with this program; if not, write to the Free Software Foundation, Inc.,
  59 Temple Place, Suite 330, Boston, MA, 02111-1307.

*/

/*$Id: ilocate.c,v 1.4.2.1.2.1 2003/01/17 00:49:04 giles Exp $ */
/* Object locating and validating for Ghostscript memory manager */
#include "ghost.h"
#include "memory_.h"
#include "errors.h"
#include "gsexit.h"
#include "gsstruct.h"
#include "iastate.h"
#include "idict.h"
#include "igc.h"		/* for gc_state_t */
#include "igcstr.h"		/* for prototype */
#include "iname.h"
#include "ipacked.h"
#include "isstate.h"
#include "iutil.h"		/* for packed_get */
#include "ivmspace.h"
#include "store.h"

/* ================ Locating ================ */

/* Locate a pointer in the chunks of a space being collected. */
/* This is only used for string garbage collection and for debugging. */
chunk_t *
gc_locate(const void *ptr, gc_state_t * gcst)
{
    const gs_ref_memory_t *mem;
    const gs_ref_memory_t *other;

    if (chunk_locate(ptr, &gcst->loc))
	return gcst->loc.cp;
    mem = gcst->loc.memory;

    /*
     * Try the stable allocator of this space, or, if the current memory
     * is the stable one, the non-stable allocator of this space.
     */

    if ((other = (const gs_ref_memory_t *)mem->stable_memory) != mem ||
	(other = gcst->spaces_indexed[mem->space >> r_space_shift]) != mem
	) {
	gcst->loc.memory = other;
	gcst->loc.cp = 0;
	if (chunk_locate(ptr, &gcst->loc))
	    return gcst->loc.cp;
    }

    /*
     * Try the other space, if there is one, including its stable allocator
     * and all save levels.  (If the original space is system space, try
     * local space.)
     */

    if (gcst->space_local != gcst->space_global) {
	gcst->loc.memory = other =
	    (mem->space == avm_local ? gcst->space_global : gcst->space_local);
	gcst->loc.cp = 0;
	if (chunk_locate(ptr, &gcst->loc))
	    return gcst->loc.cp;
	/* Try its stable allocator. */
	if (other->stable_memory != (const gs_memory_t *)other) {
	    gcst->loc.memory = (gs_ref_memory_t *)other->stable_memory;
	    gcst->loc.cp = 0;
	    if (chunk_locate(ptr, &gcst->loc))
		return gcst->loc.cp;
	    gcst->loc.memory = other;
	}
	/* Try other save levels of this space. */
	while (gcst->loc.memory->saved != 0) {
	    gcst->loc.memory = &gcst->loc.memory->saved->state;
	    gcst->loc.cp = 0;
	    if (chunk_locate(ptr, &gcst->loc))
		return gcst->loc.cp;
	}
    }

    /*
     * Try system space.  This is simpler because it isn't subject to
     * save/restore and doesn't have a separate stable allocator.
     */

    if (mem != gcst->space_system) {
	gcst->loc.memory = gcst->space_system;
	gcst->loc.cp = 0;
	if (chunk_locate(ptr, &gcst->loc))
	    return gcst->loc.cp;
    }

    /*
     * Try other save levels of the initial space, or of global space if the
     * original space was system space.  In the latter case, try all
     * levels, and its stable allocator.
     */

    switch (mem->space) {
    default:			/* system */
	other = gcst->space_global;
	if (other->stable_memory != (const gs_memory_t *)other) {
	    gcst->loc.memory = (gs_ref_memory_t *)other->stable_memory;
	    gcst->loc.cp = 0;
	    if (chunk_locate(ptr, &gcst->loc))
		return gcst->loc.cp;
	}
	gcst->loc.memory = other;
	break;
    case avm_global:
	gcst->loc.memory = gcst->space_global;
	break;
    case avm_local:
	gcst->loc.memory = gcst->space_local;
	break;
    }
    for (;;) {
	if (gcst->loc.memory != mem) {	/* don't do twice */
	    gcst->loc.cp = 0;
	    if (chunk_locate(ptr, &gcst->loc))
		return gcst->loc.cp;
	}
	if (gcst->loc.memory->saved == 0)
	    break;
	gcst->loc.memory = &gcst->loc.memory->saved->state;
    }

    /* Restore locator to a legal state and report failure. */

    gcst->loc.memory = mem;
    gcst->loc.cp = 0;
    return 0;
}

/* ================ Debugging ================ */

#ifdef DEBUG

/* Define the structure for temporarily saving allocator state. */
typedef struct alloc_temp_save_s {
	chunk_t cc;
	uint rsize;
	ref rlast;
} alloc_temp_save_t;
/* Temporarily save the state of an allocator. */
private void
alloc_temp_save(alloc_temp_save_t *pats, gs_ref_memory_t *mem)
{
    chunk_t *pcc = mem->pcc;
    obj_header_t *rcur = mem->cc.rcur;

    if (pcc != 0) {
	pats->cc = *pcc;
	*pcc = mem->cc;
    }
    if (rcur != 0) {
	pats->rsize = rcur[-1].o_size;
	rcur[-1].o_size = mem->cc.rtop - (byte *) rcur;
	/* Create the final ref, reserved for the GC. */
	pats->rlast = ((ref *) mem->cc.rtop)[-1];
	make_mark((ref *) mem->cc.rtop - 1);
    }
}
/* Restore the temporarily saved state. */
private void
alloc_temp_restore(alloc_temp_save_t *pats, gs_ref_memory_t *mem)
{
    chunk_t *pcc = mem->pcc;
    obj_header_t *rcur = mem->cc.rcur;

    if (rcur != 0) {
	rcur[-1].o_size = pats->rsize;
	((ref *) mem->cc.rtop)[-1] = pats->rlast;
    }
    if (pcc != 0)
	*pcc = pats->cc;
}

/* Validate the contents of an allocator. */
void
ialloc_validate_spaces(const gs_dual_memory_t * dmem)
{
    int i;
    gc_state_t state;
    alloc_temp_save_t
	save[countof(dmem->spaces_indexed)],
	save_stable[countof(dmem->spaces_indexed)];
    gs_ref_memory_t *mem;

    state.spaces = dmem->spaces;
    state.loc.memory = state.space_local;
    state.loc.cp = 0;

    /* Save everything we need to reset temporarily. */

    for (i = 0; i < countof(save); i++)
	if ((mem = dmem->spaces_indexed[i]) != 0) {
	    alloc_temp_save(&save[i], mem);
	    if (mem->stable_memory != (gs_memory_t *)mem)
		alloc_temp_save(&save_stable[i],
				(gs_ref_memory_t *)mem->stable_memory);
	}

    /* Validate memory. */

    for (i = 0; i < countof(save); i++)
	if ((mem = dmem->spaces_indexed[i]) != 0) {
	    ialloc_validate_memory(mem, &state);
	    if (mem->stable_memory != (gs_memory_t *)mem)
		ialloc_validate_memory((gs_ref_memory_t *)mem->stable_memory,
				       &state);
	}

    /* Undo temporary changes. */

    for (i = 0; i < countof(save); i++)
	if ((mem = dmem->spaces_indexed[i]) != 0) {
	    if (mem->stable_memory != (gs_memory_t *)mem)
		alloc_temp_restore(&save_stable[i],
				   (gs_ref_memory_t *)mem->stable_memory);
	    alloc_temp_restore(&save[i], mem);
	}
}
void
ialloc_validate_memory(const gs_ref_memory_t * mem, gc_state_t * gcst)
{
    const gs_ref_memory_t *smem;
    int level;

    for (smem = mem, level = 0; smem != 0;
	 smem = &smem->saved->state, --level
	) {
	const chunk_t *cp;
	int i;

	if_debug3('6', "[6]validating memory 0x%lx, space %d, level %d\n",
		  (ulong) mem, mem->space, level);
	/* Validate chunks. */
	for (cp = smem->cfirst; cp != 0; cp = cp->cnext)
	    ialloc_validate_chunk(cp, gcst);
	/* Validate freelists. */
	for (i = 0; i < num_freelists; ++i) {
	    uint free_size = i << log2_obj_align_mod;
	    const obj_header_t *pfree;

	    for (pfree = mem->freelists[i]; pfree != 0;
		 pfree = *(const obj_header_t * const *)pfree
		) {
		uint size = pfree[-1].o_size;

		if (pfree[-1].o_type != &st_free) {
		    lprintf3("Non-free object 0x%lx(%u) on freelist %i!\n",
			     (ulong) pfree, size, i);
		    break;
		}
		if ((i == LARGE_FREELIST_INDEX && size < max_freelist_size) ||
		 (i != LARGE_FREELIST_INDEX &&
		 (size < free_size - obj_align_mask || size > free_size))) {
		    lprintf3("Object 0x%lx(%u) size wrong on freelist %i!\n",
			     (ulong) pfree, size, i);
		    break;
		}
	    }
	}
    };
}

/* Check the validity of an object's size. */
inline private bool
object_size_valid(const obj_header_t * pre, uint size, const chunk_t * cp)
{
    return (pre->o_alone ? (const byte *)pre == cp->cbase :
	    size <= cp->ctop - (const byte *)(pre + 1));
}

/* Validate all the objects in a chunk. */
private void ialloc_validate_ref(P2(const ref *, gc_state_t *));
private void ialloc_validate_ref_packed(P2(const ref_packed *, gc_state_t *));
void
ialloc_validate_chunk(const chunk_t * cp, gc_state_t * gcst)
{
    if_debug_chunk('6', "[6]validating chunk", cp);
    SCAN_CHUNK_OBJECTS(cp);
    DO_ALL
	if (pre->o_type == &st_free) {
	    if (!object_size_valid(pre, size, cp))
		lprintf3("Bad free object 0x%lx(%lu), in chunk 0x%lx!\n",
			 (ulong) (pre + 1), (ulong) size, (ulong) cp);
	} else
	    ialloc_validate_object(pre + 1, cp, gcst);
    if_debug3('7', " [7]validating %s(%lu) 0x%lx\n",
	      struct_type_name_string(pre->o_type),
	      (ulong) size, (ulong) pre);
    if (pre->o_type == &st_refs) {
	const ref_packed *rp = (const ref_packed *)(pre + 1);
	const char *end = (const char *)rp + size;

	while ((const char *)rp < end) {
	    ialloc_validate_ref_packed(rp, gcst);
	    rp = packed_next(rp);
	}
    } else {
	struct_proc_enum_ptrs((*proc)) = pre->o_type->enum_ptrs;
	uint index = 0;
	enum_ptr_t eptr;
	gs_ptr_type_t ptype;

	if (proc != gs_no_struct_enum_ptrs)
	    for (; (ptype = (*proc) (pre + 1, size, index, &eptr, pre->o_type, NULL)) != 0; ++index)
		if (eptr.ptr == 0)
		    DO_NOTHING;
		else if (ptype == ptr_struct_type)
		    ialloc_validate_object(eptr.ptr, NULL, gcst);
		else if (ptype == ptr_ref_type)
		    ialloc_validate_ref_packed(eptr.ptr, gcst);
    }
    END_OBJECTS_SCAN
}
/* Validate a ref. */
private void
ialloc_validate_ref_packed(const ref_packed * rp, gc_state_t * gcst)
{
    if (r_is_packed(rp)) {
	ref unpacked;

	packed_get(rp, &unpacked);
	ialloc_validate_ref(&unpacked, gcst);
    } else {
	ialloc_validate_ref((const ref *)rp, gcst);
    }
}
private void
ialloc_validate_ref(const ref * pref, gc_state_t * gcst)
{
    const void *optr;
    const ref *rptr;
    const char *tname;
    uint size;

    if (!gs_debug_c('?'))
	return;			/* no check */
    if (r_space(pref) == avm_foreign)
	return;
    switch (r_type(pref)) {
	case t_file:
	    optr = pref->value.pfile;
	    goto cks;
	case t_device:
	    optr = pref->value.pdevice;
	    goto cks;
	case t_fontID:
	case t_struct:
	case t_astruct:
	    optr = pref->value.pstruct;
cks:	    if (optr != 0)
		ialloc_validate_object(optr, NULL, gcst);
	    break;
	case t_name:
	    if (name_index_ptr(name_index(pref)) != pref->value.pname) {
		lprintf3("At 0x%lx, bad name %u, pname = 0x%lx\n",
			 (ulong) pref, (uint)name_index(pref),
			 (ulong) pref->value.pname);
		break;
	    } {
		ref sref;

		name_string_ref(pref, &sref);
		if (r_space(&sref) != avm_foreign &&
		    !gc_locate(sref.value.const_bytes, gcst)
		    ) {
		    lprintf4("At 0x%lx, bad name %u, pname = 0x%lx, string 0x%lx not in any chunk\n",
			     (ulong) pref, (uint) r_size(pref),
			     (ulong) pref->value.pname,
			     (ulong) sref.value.const_bytes);
		}
	    }
	    break;
	case t_string:
	    if (r_size(pref) != 0 && !gc_locate(pref->value.bytes, gcst))
		lprintf3("At 0x%lx, string ptr 0x%lx[%u] not in any chunk\n",
			 (ulong) pref, (ulong) pref->value.bytes,
			 (uint) r_size(pref));
	    break;
	case t_array:
	    if (r_size(pref) == 0)
		break;
	    rptr = pref->value.refs;
	    size = r_size(pref);
	    tname = "array";
cka:	    if (!gc_locate(rptr, gcst)) {
		lprintf3("At 0x%lx, %s 0x%lx not in any chunk\n",
			 (ulong) pref, tname, (ulong) rptr);
		break;
	    } {
		uint i;

		for (i = 0; i < size; ++i) {
		    const ref *elt = rptr + i;

		    if (r_is_packed(elt))
			lprintf5("At 0x%lx, %s 0x%lx[%u] element %u is not a ref\n",
				 (ulong) pref, tname, (ulong) rptr, size, i);
		}
	    }
	    break;
	case t_shortarray:
	case t_mixedarray:
	    if (r_size(pref) == 0)
		break;
	    optr = pref->value.packed;
	    if (!gc_locate(optr, gcst))
		lprintf2("At 0x%lx, packed array 0x%lx not in any chunk\n",
			 (ulong) pref, (ulong) optr);
	    break;
	case t_dictionary:
	    {
		const dict *pdict = pref->value.pdict;

		if (!r_has_type(&pdict->values, t_array) ||
		    !r_is_array(&pdict->keys) ||
		    !r_has_type(&pdict->count, t_integer) ||
		    !r_has_type(&pdict->maxlength, t_integer)
		    )
		    lprintf2("At 0x%lx, invalid dict 0x%lx\n",
			     (ulong) pref, (ulong) pdict);
		rptr = (const ref *)pdict;
	    }
	    size = sizeof(dict) / sizeof(ref);
	    tname = "dict";
	    goto cka;
    }
}

/* Validate an object. */
void
ialloc_validate_object(const obj_header_t * ptr, const chunk_t * cp,
		       gc_state_t * gcst)
{
    const obj_header_t *pre = ptr - 1;
    ulong size = pre_obj_contents_size(pre);
    gs_memory_type_ptr_t otype = pre->o_type;
    const char *oname;

    if (!gs_debug_c('?'))
	return;			/* no check */
    if (cp == 0 && gcst != 0) {
	gc_state_t st;

	st = *gcst;		/* no side effects! */
	if (!(cp = gc_locate(pre, &st))) {
	    lprintf1("Object 0x%lx not in any chunk!\n",
		     (ulong) ptr);
	    return;		/*gs_abort(); */
	}
    }
    if (otype == &st_free) {
	lprintf3("Reference to free object 0x%lx(%lu), in chunk 0x%lx!\n",
		 (ulong) ptr, (ulong) size, (ulong) cp);
	gs_abort();
    }
    if ((cp != 0 && !object_size_valid(pre, size, cp)) ||
	otype->ssize == 0 ||
	size % otype->ssize != 0 ||
	(oname = struct_type_name_string(otype),
	 *oname < 33 || *oname > 126)
	) {
	lprintf2("Bad object 0x%lx(%lu),\n",
		 (ulong) ptr, (ulong) size);
	dprintf2(" ssize = %u, in chunk 0x%lx!\n",
		 otype->ssize, (ulong) cp);
	gs_abort();
    }
}

#else /* !DEBUG */

void
ialloc_validate_spaces(const gs_dual_memory_t * dmem)
{
}

void
ialloc_validate_memory(const gs_ref_memory_t * mem, gc_state_t * gcst)
{
}

void
ialloc_validate_chunk(const chunk_t * cp, gc_state_t * gcst)
{
}

void
ialloc_validate_object(const obj_header_t * ptr, const chunk_t * cp,
		       gc_state_t * gcst)
{
}

#endif /* (!)DEBUG */