path: root/base/gsmemory.c

/* Copyright (C) 2001-2023 Artifex Software, Inc.
   All Rights Reserved.

   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied,
   modified or distributed except as expressly authorized under the terms
   of the license contained in the file LICENSE in this distribution.

   Refer to licensing information at http://www.artifex.com or contact
   Artifex Software, Inc.,  39 Mesa Street, Suite 108A, San Francisco,
   CA 94129, USA, for further information.
*/


/* Generic allocator support */
#include "memory_.h"
#include "stdint_.h"
#include "gdebug.h"
#include "gstypes.h"
#include "gsmemory.h"
#include "gsmdebug.h"
#include "gsrefct.h"		/* to check prototype */
#include "gsstruct.h"		/* ditto */

/* Define the fill patterns for unallocated memory. */
const byte gs_alloc_fill_alloc = 0xa1;
const byte gs_alloc_fill_block = 0xb1;
const byte gs_alloc_fill_collected = 0xc1;
const byte gs_alloc_fill_deleted = 0xd1;
const byte gs_alloc_fill_free = 0xf1;

/* A 'structure' type descriptor for free blocks. */
gs_public_st_simple(st_free, byte, "(free)");

/* The 'structure' type descriptor for bytes. */
gs_public_st_simple(st_bytes, byte, "bytes");

/* The structure type descriptor for GC roots. */
public_st_gc_root_t();

/* The descriptors for elements and arrays of const strings. */
private_st_const_string();
public_st_const_string_element();

/* GC procedures for bytestrings */
gs_ptr_type_t
enum_bytestring(enum_ptr_t *pep, const gs_bytestring *pbs)
{
    return (pbs->bytes ? ENUM_OBJ(pbs->bytes) : ENUM_STRING(pbs));
}
gs_ptr_type_t
enum_const_bytestring(enum_ptr_t *pep, const gs_const_bytestring *pbs)
{
    return (pbs->bytes ? ENUM_OBJ(pbs->bytes) : ENUM_CONST_STRING(pbs));
}
void
reloc_bytestring(gs_bytestring *pbs, gc_state_t *gcst)
{
    if (pbs->bytes) {
        byte *bytes = pbs->bytes;
        long offset = pbs->data - bytes;

        pbs->bytes = bytes = RELOC_OBJ(bytes);
        pbs->data = bytes + offset;
    } else
        RELOC_STRING_VAR(*(gs_string *)pbs);
}
void
reloc_const_bytestring(gs_const_bytestring *pbs, gc_state_t *gcst)
{
    if (pbs->bytes) {
        const byte *bytes = pbs->bytes;
        long offset = pbs->data - bytes;

        pbs->bytes = bytes = RELOC_OBJ(bytes);
        pbs->data = bytes + offset;
    } else
        RELOC_CONST_STRING_VAR(*(gs_const_string *)pbs);
}

/* Fill an unoccupied block with a pattern. */
/* Note that the block size may be too large for a single memset. */
void
gs_alloc_memset(void *ptr, int /*byte */ fill, size_t lsize)
{
    size_t msize = lsize;
    char *p = ptr;
    int isize;

    for (; msize; msize -= isize, p += isize) {
        isize = min(msize, max_int);
        memset(p, fill, isize);
    }
}

/*
 * Either allocate (if obj == 0) or resize (if obj != 0) a structure array.
 * If obj != 0, pstype is used only for checking (in DEBUG configurations).
 */
void *
gs_resize_struct_array(gs_memory_t *mem, void *obj, size_t num_elements,
                       gs_memory_type_ptr_t pstype, client_name_t cname)
{
    if (obj == 0)
        return gs_alloc_struct_array(mem, num_elements, void, pstype, cname);
#ifdef DEBUG
    if (gs_object_type(mem, obj) != pstype) {
        lprintf3("resize_struct_array "PRI_INTPTR", type was "PRI_INTPTR", expected "PRI_INTPTR"!\n",
                 (intptr_t)obj, (intptr_t)gs_object_type(mem, obj), (intptr_t)pstype);
        return 0;
    }
#endif
    return gs_resize_object(mem, obj, num_elements, cname);
}

/* Allocate a structure using a "raw memory" allocator.
 * really just an alias for gs_alloc_struct_immovable
 * with the clients false expectation that it is saving memory
 */

void *
gs_raw_alloc_struct_immovable(gs_memory_t * rmem,
                              gs_memory_type_ptr_t pstype,
                              client_name_t cname)
{
    return gs_alloc_bytes_immovable(rmem, gs_struct_type_size(pstype), cname);
}

/* No-op freeing procedures */
void
gs_ignore_free_object(gs_memory_t * mem, void *data, client_name_t cname)
{
}
void
gs_ignore_free_string(gs_memory_t * mem, byte * data, size_t nbytes,
                      client_name_t cname)
{
}

/* Deconstifying freeing procedures. */
/* These procedures rely on a severely deprecated pun. */
void
gs_free_const_object(gs_memory_t * mem, const void *data, client_name_t cname)
{
    union { const void *r; void *w; } u;

    u.r = data;
    gs_free_object(mem, u.w, cname);
}
void
gs_free_const_string(gs_memory_t * mem, const byte * data, size_t nbytes,
                     client_name_t cname)
{
    union { const byte *r; byte *w; } u;

    u.r = data;
    gs_free_string(mem, u.w, nbytes, cname);
}

/* Free a [const] bytestring. */
void
gs_free_bytestring(gs_memory_t *mem, gs_bytestring *pbs, client_name_t cname)
{
    if (pbs->bytes)
        gs_free_object(mem, pbs->bytes, cname);
    else
        gs_free_string(mem, pbs->data, pbs->size, cname);
}
void
gs_free_const_bytestring(gs_memory_t *mem, gs_const_bytestring *pbs,
                         client_name_t cname)
{
    if (pbs->bytes)
        gs_free_const_object(mem, pbs->bytes, cname);
    else
        gs_free_const_string(mem, pbs->data, pbs->size, cname);
}

/* No-op consolidation procedure */
void
gs_ignore_consolidate_free(gs_memory_t *mem)
{
}

/* No-op pointer enumeration procedure */
ENUM_PTRS_BEGIN_PROC(gs_no_struct_enum_ptrs)
{
    return 0;
    ENUM_PTRS_END_PROC
}

/* No-op pointer relocation procedure */
RELOC_PTRS_BEGIN(gs_no_struct_reloc_ptrs)
{
}
RELOC_PTRS_END

/* Get the size of a structure from the descriptor. */
uint
gs_struct_type_size(gs_memory_type_ptr_t pstype)
{
    return pstype->ssize;
}

/* Get the name of a structure from the descriptor. */
struct_name_t
gs_struct_type_name(gs_memory_type_ptr_t pstype)
{
    return pstype->sname;
}

/* Register a structure root. */
int
gs_register_struct_root(gs_memory_t *mem, gs_gc_root_t **root,
                        void **pp, client_name_t cname)
{
    return gs_register_root(mem, root, ptr_struct_type, pp, cname);
}

/* ---------------- Reference counting ---------------- */

#ifdef DEBUG

static const char *
rc_object_type_name(const void *vp, const rc_header *prc)
{
    gs_memory_type_ptr_t pstype;

    if (prc->memory == 0)
        return "(unknown)";
    pstype = gs_object_type(prc->memory, vp);
    if ((uintptr_t)pstype < 10000)
        return ("?????");
    if (prc->free != rc_free_struct_only) {
        /*
         * This object might be stack-allocated or have other unusual memory
         * management properties.  Make some reasonableness checks.
         * ****** THIS IS A HACK. ******
         */
        long dist;

        dist = (const char *)&dist - (const char *)vp;
        if (dist < 10000 && dist > -10000)
            return "(on stack)";
        if ((uintptr_t)pstype < 0x10000)
            return "(anomalous)";
    }
    return client_name_string(gs_struct_type_name(pstype));
}

/* Trace reference count operations. */
void
rc_trace_init_free(const void *vp, const rc_header *prc)
{
    dmprintf3(prc->memory, "[^]%s "PRI_INTPTR" init = %ld\n",
              rc_object_type_name(vp, prc), (intptr_t)vp, (long)prc->ref_count);
}
void
rc_trace_free_struct(const void *vp, const rc_header *prc, client_name_t cname)
{
    dmprintf3(prc->memory, "[^]%s "PRI_INTPTR" => free (%s)\n",
              rc_object_type_name(vp, prc),
              (intptr_t)vp, client_name_string(cname));
}
void
rc_trace_increment(const void *vp, const rc_header *prc)
{
    dmprintf3(prc->memory, "[^]%s "PRI_INTPTR" ++ => %ld\n",
              rc_object_type_name(vp, prc),
              (intptr_t)vp, (long)prc->ref_count);
}
void
rc_trace_adjust(const void *vp, const rc_header *prc, int delta, const char *cname)
{
    dmprintf5(prc->memory, "[^]%s "PRI_INTPTR" %+d => %ld (%s)\n",
              rc_object_type_name(vp, prc),
              (intptr_t)vp, delta, (long)(prc->ref_count + delta), cname);
}

#endif /* DEBUG */

/* Normal freeing routine for reference-counted structures. */
void
rc_free_struct_only(gs_memory_t * mem, void *data, client_name_t cname)
{
    if (mem != 0)
        gs_free_object(mem, data, cname);
}

/* ---------------- Basic-structure GC procedures ---------------- */

/* Enumerate pointers */
ENUM_PTRS_BEGIN_PROC(basic_enum_ptrs)
{
    const gc_struct_data_t *psd = pstype->proc_data;

    /* This check is primarily for misuse of the alloc_struct_array */
    /* with number of elements 0 and allocation not passing 'element' */
    if (size == 0) {
#ifdef DEBUG
        dmprintf2(mem, "  basic_enum_ptrs: Attempt to enum 0 size structure at "PRI_INTPTR", type: %s\n",
                  (intptr_t)vptr, pstype->sname);
#endif
        return 0;
    }
    if (index < psd->num_ptrs) {
        const gc_ptr_element_t *ppe = &psd->ptrs[index];
        EV_CONST char *pptr = (EV_CONST char *)vptr + ppe->offset;

#ifdef DEBUG
        /* some extra checking to make sure we aren't out of bounds */
        if (ppe->offset > size - sizeof(void *)) {
            dmprintf4(mem, "  basic_enum_ptrs: Attempt to enum ptr with offset=%d beyond size=%d: structure at "PRI_INTPTR", type: %s\n",
                      ppe->offset, size, (intptr_t)vptr, pstype->sname);
            return 0;
        }
#endif
        switch ((gc_ptr_type_index_t)ppe->type) {
            case GC_ELT_OBJ:
                return ENUM_OBJ(*(const void *EV_CONST *)pptr);
            case GC_ELT_STRING:
                return ENUM_STRING((const gs_string *)pptr);
            case GC_ELT_CONST_STRING:
                return ENUM_CONST_STRING((const gs_const_string *)pptr);
        }
    }
    if (!psd->super_type)
        return 0;
    return ENUM_USING(*(psd->super_type),
                      (EV_CONST void *)
                        ((EV_CONST char *)vptr + psd->super_offset),
                      pstype->ssize, index - psd->num_ptrs);
}
ENUM_PTRS_END_PROC

/* Relocate pointers */
RELOC_PTRS_BEGIN(basic_reloc_ptrs)
{
    const gc_struct_data_t *psd = pstype->proc_data;
    uint i;

    for (i = 0; i < psd->num_ptrs; ++i) {
        const gc_ptr_element_t *ppe = &psd->ptrs[i];
        char *pptr = (char *)vptr + ppe->offset;

        switch ((gc_ptr_type_index_t) ppe->type) {
            case GC_ELT_OBJ:
                RELOC_OBJ_VAR(*(void **)pptr);
                break;
            case GC_ELT_STRING:
                RELOC_STRING_VAR(*(gs_string *)pptr);
                break;
            case GC_ELT_CONST_STRING:
                RELOC_CONST_STRING_VAR(*(gs_const_string *)pptr);
                break;
        }
    }
    if (psd->super_type)
        RELOC_USING(*(psd->super_type),
                      (void *)((char *)vptr + psd->super_offset),
                      pstype->ssize);
} RELOC_PTRS_END