zstd_cwksp.h

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/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 * All rights reserved.
 *
 * This source code is licensed under both the BSD-style license (found in the
 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
 * in the COPYING file in the root directory of this source tree).
 * You may select, at your option, one of the above-listed licenses.
 */
 
#ifndef ZSTD_CWKSP_H
#define ZSTD_CWKSP_H
 
/*-*************************************
*  Dependencies
***************************************/
#include "../common/allocations.h"  /* ZSTD_customMalloc, ZSTD_customFree */
#include "../common/zstd_internal.h"
#include "../common/portability_macros.h"
 
#if defined (__cplusplus)
extern "C" {
#endif
 
/*-*************************************
*  Constants
***************************************/
 
/* Since the workspace is effectively its own little malloc implementation /
 * arena, when we run under ASAN, we should similarly insert redzones between
 * each internal element of the workspace, so ASAN will catch overruns that
 * reach outside an object but that stay inside the workspace.
 *
 * This defines the size of that redzone.
 */
#ifndef ZSTD_CWKSP_ASAN_REDZONE_SIZE
#define ZSTD_CWKSP_ASAN_REDZONE_SIZE 128
#endif
 
 
/* Set our tables and aligneds to align by 64 bytes */
#define ZSTD_CWKSP_ALIGNMENT_BYTES 64
 
/*-*************************************
*  Structures
***************************************/
typedef enum {
    ZSTD_cwksp_alloc_objects,
    ZSTD_cwksp_alloc_aligned_init_once,
    ZSTD_cwksp_alloc_aligned,
    ZSTD_cwksp_alloc_buffers
} ZSTD_cwksp_alloc_phase_e;
 
typedef enum {
    ZSTD_cwksp_dynamic_alloc,
    ZSTD_cwksp_static_alloc
} ZSTD_cwksp_static_alloc_e;
 
typedef struct {
    void* workspace;
    void* workspaceEnd;
 
    void* objectEnd;
    void* tableEnd;
    void* tableValidEnd;
    void* allocStart;
    void* initOnceStart;
 
    BYTE allocFailed;
    int workspaceOversizedDuration;
    ZSTD_cwksp_alloc_phase_e phase;
    ZSTD_cwksp_static_alloc_e isStatic;
} ZSTD_cwksp;
 
/*-*************************************
*  Functions
***************************************/
 
MEM_STATIC size_t ZSTD_cwksp_available_space(ZSTD_cwksp* ws);
MEM_STATIC void*  ZSTD_cwksp_initialAllocStart(ZSTD_cwksp* ws);
 
MEM_STATIC void ZSTD_cwksp_assert_internal_consistency(ZSTD_cwksp* ws) {
    (void)ws;
    assert(ws->workspace <= ws->objectEnd);
    assert(ws->objectEnd <= ws->tableEnd);
    assert(ws->objectEnd <= ws->tableValidEnd);
    assert(ws->tableEnd <= ws->allocStart);
    assert(ws->tableValidEnd <= ws->allocStart);
    assert(ws->allocStart <= ws->workspaceEnd);
    assert(ws->initOnceStart <= ZSTD_cwksp_initialAllocStart(ws));
    assert(ws->workspace <= ws->initOnceStart);
#if ZSTD_MEMORY_SANITIZER
    {
        intptr_t const offset = __msan_test_shadow(ws->initOnceStart,
            (U8*)ZSTD_cwksp_initialAllocStart(ws) - (U8*)ws->initOnceStart);
        (void)offset;
#if defined(ZSTD_MSAN_PRINT)
        if(offset!=-1) {
            __msan_print_shadow((U8*)ws->initOnceStart + offset - 8, 32);
        }
#endif
        assert(offset==-1);
    };
#endif
}
 
MEM_STATIC size_t ZSTD_cwksp_align(size_t size, size_t const align) {
    size_t const mask = align - 1;
    assert((align & mask) == 0);
    return (size + mask) & ~mask;
}
 
MEM_STATIC size_t ZSTD_cwksp_alloc_size(size_t size) {
    if (size == 0)
        return 0;
#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    return size + 2 * ZSTD_CWKSP_ASAN_REDZONE_SIZE;
#else
    return size;
#endif
}
 
MEM_STATIC size_t ZSTD_cwksp_aligned_alloc_size(size_t size) {
    return ZSTD_cwksp_alloc_size(ZSTD_cwksp_align(size, ZSTD_CWKSP_ALIGNMENT_BYTES));
}
 
MEM_STATIC size_t ZSTD_cwksp_slack_space_required(void) {
    /* For alignment, the wksp will always allocate an additional 2*ZSTD_CWKSP_ALIGNMENT_BYTES
     * bytes to align the beginning of tables section and end of buffers;
     */
    size_t const slackSpace = ZSTD_CWKSP_ALIGNMENT_BYTES * 2;
    return slackSpace;
}
 
 
MEM_STATIC size_t ZSTD_cwksp_bytes_to_align_ptr(void* ptr, const size_t alignBytes) {
    size_t const alignBytesMask = alignBytes - 1;
    size_t const bytes = (alignBytes - ((size_t)ptr & (alignBytesMask))) & alignBytesMask;
    assert((alignBytes & alignBytesMask) == 0);
    assert(bytes < alignBytes);
    return bytes;
}
 
MEM_STATIC void*  ZSTD_cwksp_initialAllocStart(ZSTD_cwksp* ws) {
    return (void*)((size_t)ws->workspaceEnd & ~(ZSTD_CWKSP_ALIGNMENT_BYTES-1));
}
 
MEM_STATIC void*
ZSTD_cwksp_reserve_internal_buffer_space(ZSTD_cwksp* ws, size_t const bytes)
{
    void* const alloc = (BYTE*)ws->allocStart - bytes;
    void* const bottom = ws->tableEnd;
    DEBUGLOG(5, "cwksp: reserving %p %zd bytes, %zd bytes remaining",
        alloc, bytes, ZSTD_cwksp_available_space(ws) - bytes);
    ZSTD_cwksp_assert_internal_consistency(ws);
    assert(alloc >= bottom);
    if (alloc < bottom) {
        DEBUGLOG(4, "cwksp: alloc failed!");
        ws->allocFailed = 1;
        return NULL;
    }
    /* the area is reserved from the end of wksp.
     * If it overlaps with tableValidEnd, it voids guarantees on values' range */
    if (alloc < ws->tableValidEnd) {
        ws->tableValidEnd = alloc;
    }
    ws->allocStart = alloc;
    return alloc;
}
 
MEM_STATIC size_t
ZSTD_cwksp_internal_advance_phase(ZSTD_cwksp* ws, ZSTD_cwksp_alloc_phase_e phase)
{
    assert(phase >= ws->phase);
    if (phase > ws->phase) {
        /* Going from allocating objects to allocating initOnce / tables */
        if (ws->phase < ZSTD_cwksp_alloc_aligned_init_once &&
            phase >= ZSTD_cwksp_alloc_aligned_init_once) {
            ws->tableValidEnd = ws->objectEnd;
            ws->initOnceStart = ZSTD_cwksp_initialAllocStart(ws);
 
            {   /* Align the start of the tables to 64 bytes. Use [0, 63] bytes */
                void *const alloc = ws->objectEnd;
                size_t const bytesToAlign = ZSTD_cwksp_bytes_to_align_ptr(alloc, ZSTD_CWKSP_ALIGNMENT_BYTES);
                void *const objectEnd = (BYTE *) alloc + bytesToAlign;
                DEBUGLOG(5, "reserving table alignment addtl space: %zu", bytesToAlign);
                RETURN_ERROR_IF(objectEnd > ws->workspaceEnd, memory_allocation,
                                "table phase - alignment initial allocation failed!");
                ws->objectEnd = objectEnd;
                ws->tableEnd = objectEnd;  /* table area starts being empty */
                if (ws->tableValidEnd < ws->tableEnd) {
                    ws->tableValidEnd = ws->tableEnd;
                }
            }
        }
        ws->phase = phase;
        ZSTD_cwksp_assert_internal_consistency(ws);
    }
    return 0;
}
 
MEM_STATIC int ZSTD_cwksp_owns_buffer(const ZSTD_cwksp* ws, const void* ptr)
{
    return (ptr != NULL) && (ws->workspace <= ptr) && (ptr < ws->workspaceEnd);
}
 
MEM_STATIC void*
ZSTD_cwksp_reserve_internal(ZSTD_cwksp* ws, size_t bytes, ZSTD_cwksp_alloc_phase_e phase)
{
    void* alloc;
    if (ZSTD_isError(ZSTD_cwksp_internal_advance_phase(ws, phase)) || bytes == 0) {
        return NULL;
    }
 
#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    /* over-reserve space */
    bytes += 2 * ZSTD_CWKSP_ASAN_REDZONE_SIZE;
#endif
 
    alloc = ZSTD_cwksp_reserve_internal_buffer_space(ws, bytes);
 
#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    /* Move alloc so there's ZSTD_CWKSP_ASAN_REDZONE_SIZE unused space on
     * either size. */
    if (alloc) {
        alloc = (BYTE *)alloc + ZSTD_CWKSP_ASAN_REDZONE_SIZE;
        if (ws->isStatic == ZSTD_cwksp_dynamic_alloc) {
            /* We need to keep the redzone poisoned while unpoisoning the bytes that
             * are actually allocated. */
            __asan_unpoison_memory_region(alloc, bytes - 2 * ZSTD_CWKSP_ASAN_REDZONE_SIZE);
        }
    }
#endif
 
    return alloc;
}
 
MEM_STATIC BYTE* ZSTD_cwksp_reserve_buffer(ZSTD_cwksp* ws, size_t bytes)
{
    return (BYTE*)ZSTD_cwksp_reserve_internal(ws, bytes, ZSTD_cwksp_alloc_buffers);
}
 
MEM_STATIC void* ZSTD_cwksp_reserve_aligned_init_once(ZSTD_cwksp* ws, size_t bytes)
{
    size_t const alignedBytes = ZSTD_cwksp_align(bytes, ZSTD_CWKSP_ALIGNMENT_BYTES);
    void* ptr = ZSTD_cwksp_reserve_internal(ws, alignedBytes, ZSTD_cwksp_alloc_aligned_init_once);
    assert(((size_t)ptr & (ZSTD_CWKSP_ALIGNMENT_BYTES-1))== 0);
    if(ptr && ptr < ws->initOnceStart) {
        /* We assume the memory following the current allocation is either:
         * 1. Not usable as initOnce memory (end of workspace)
         * 2. Another initOnce buffer that has been allocated before (and so was previously memset)
         * 3. An ASAN redzone, in which case we don't want to write on it
         * For these reasons it should be fine to not explicitly zero every byte up to ws->initOnceStart.
         * Note that we assume here that MSAN and ASAN cannot run in the same time. */
        ZSTD_memset(ptr, 0, MIN((size_t)((U8*)ws->initOnceStart - (U8*)ptr), alignedBytes));
        ws->initOnceStart = ptr;
    }
#if ZSTD_MEMORY_SANITIZER
    assert(__msan_test_shadow(ptr, bytes) == -1);
#endif
    return ptr;
}
 
MEM_STATIC void* ZSTD_cwksp_reserve_aligned(ZSTD_cwksp* ws, size_t bytes)
{
    void* ptr = ZSTD_cwksp_reserve_internal(ws, ZSTD_cwksp_align(bytes, ZSTD_CWKSP_ALIGNMENT_BYTES),
                                            ZSTD_cwksp_alloc_aligned);
    assert(((size_t)ptr & (ZSTD_CWKSP_ALIGNMENT_BYTES-1))== 0);
    return ptr;
}
 
MEM_STATIC void* ZSTD_cwksp_reserve_table(ZSTD_cwksp* ws, size_t bytes)
{
    const ZSTD_cwksp_alloc_phase_e phase = ZSTD_cwksp_alloc_aligned_init_once;
    void* alloc;
    void* end;
    void* top;
 
    /* We can only start allocating tables after we are done reserving space for objects at the
     * start of the workspace */
    if(ws->phase < phase) {
        if (ZSTD_isError(ZSTD_cwksp_internal_advance_phase(ws, phase))) {
            return NULL;
        }
    }
    alloc = ws->tableEnd;
    end = (BYTE *)alloc + bytes;
    top = ws->allocStart;
 
    DEBUGLOG(5, "cwksp: reserving %p table %zd bytes, %zd bytes remaining",
        alloc, bytes, ZSTD_cwksp_available_space(ws) - bytes);
    assert((bytes & (sizeof(U32)-1)) == 0);
    ZSTD_cwksp_assert_internal_consistency(ws);
    assert(end <= top);
    if (end > top) {
        DEBUGLOG(4, "cwksp: table alloc failed!");
        ws->allocFailed = 1;
        return NULL;
    }
    ws->tableEnd = end;
 
#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    if (ws->isStatic == ZSTD_cwksp_dynamic_alloc) {
        __asan_unpoison_memory_region(alloc, bytes);
    }
#endif
 
    assert((bytes & (ZSTD_CWKSP_ALIGNMENT_BYTES-1)) == 0);
    assert(((size_t)alloc & (ZSTD_CWKSP_ALIGNMENT_BYTES-1))== 0);
    return alloc;
}
 
MEM_STATIC void* ZSTD_cwksp_reserve_object(ZSTD_cwksp* ws, size_t bytes)
{
    size_t const roundedBytes = ZSTD_cwksp_align(bytes, sizeof(void*));
    void* alloc = ws->objectEnd;
    void* end = (BYTE*)alloc + roundedBytes;
 
#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    /* over-reserve space */
    end = (BYTE *)end + 2 * ZSTD_CWKSP_ASAN_REDZONE_SIZE;
#endif
 
    DEBUGLOG(4,
        "cwksp: reserving %p object %zd bytes (rounded to %zd), %zd bytes remaining",
        alloc, bytes, roundedBytes, ZSTD_cwksp_available_space(ws) - roundedBytes);
    assert((size_t)alloc % ZSTD_ALIGNOF(void*) == 0);
    assert(bytes % ZSTD_ALIGNOF(void*) == 0);
    ZSTD_cwksp_assert_internal_consistency(ws);
    /* we must be in the first phase, no advance is possible */
    if (ws->phase != ZSTD_cwksp_alloc_objects || end > ws->workspaceEnd) {
        DEBUGLOG(3, "cwksp: object alloc failed!");
        ws->allocFailed = 1;
        return NULL;
    }
    ws->objectEnd = end;
    ws->tableEnd = end;
    ws->tableValidEnd = end;
 
#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    /* Move alloc so there's ZSTD_CWKSP_ASAN_REDZONE_SIZE unused space on
     * either size. */
    alloc = (BYTE*)alloc + ZSTD_CWKSP_ASAN_REDZONE_SIZE;
    if (ws->isStatic == ZSTD_cwksp_dynamic_alloc) {
        __asan_unpoison_memory_region(alloc, bytes);
    }
#endif
 
    return alloc;
}
 
MEM_STATIC void ZSTD_cwksp_mark_tables_dirty(ZSTD_cwksp* ws)
{
    DEBUGLOG(4, "cwksp: ZSTD_cwksp_mark_tables_dirty");
 
#if ZSTD_MEMORY_SANITIZER && !defined (ZSTD_MSAN_DONT_POISON_WORKSPACE)
    /* To validate that the table reuse logic is sound, and that we don't
     * access table space that we haven't cleaned, we re-"poison" the table
     * space every time we mark it dirty.
     * Since tableValidEnd space and initOnce space may overlap we don't poison
     * the initOnce portion as it break its promise. This means that this poisoning
     * check isn't always applied fully. */
    {
        size_t size = (BYTE*)ws->tableValidEnd - (BYTE*)ws->objectEnd;
        assert(__msan_test_shadow(ws->objectEnd, size) == -1);
        if((BYTE*)ws->tableValidEnd < (BYTE*)ws->initOnceStart) {
            __msan_poison(ws->objectEnd, size);
        } else {
            assert(ws->initOnceStart >= ws->objectEnd);
            __msan_poison(ws->objectEnd, (BYTE*)ws->initOnceStart - (BYTE*)ws->objectEnd);
        }
    }
#endif
 
    assert(ws->tableValidEnd >= ws->objectEnd);
    assert(ws->tableValidEnd <= ws->allocStart);
    ws->tableValidEnd = ws->objectEnd;
    ZSTD_cwksp_assert_internal_consistency(ws);
}
 
MEM_STATIC void ZSTD_cwksp_mark_tables_clean(ZSTD_cwksp* ws) {
    DEBUGLOG(4, "cwksp: ZSTD_cwksp_mark_tables_clean");
    assert(ws->tableValidEnd >= ws->objectEnd);
    assert(ws->tableValidEnd <= ws->allocStart);
    if (ws->tableValidEnd < ws->tableEnd) {
        ws->tableValidEnd = ws->tableEnd;
    }
    ZSTD_cwksp_assert_internal_consistency(ws);
}
 
MEM_STATIC void ZSTD_cwksp_clean_tables(ZSTD_cwksp* ws) {
    DEBUGLOG(4, "cwksp: ZSTD_cwksp_clean_tables");
    assert(ws->tableValidEnd >= ws->objectEnd);
    assert(ws->tableValidEnd <= ws->allocStart);
    if (ws->tableValidEnd < ws->tableEnd) {
        ZSTD_memset(ws->tableValidEnd, 0, (size_t)((BYTE*)ws->tableEnd - (BYTE*)ws->tableValidEnd));
    }
    ZSTD_cwksp_mark_tables_clean(ws);
}
 
MEM_STATIC void ZSTD_cwksp_clear_tables(ZSTD_cwksp* ws) {
    DEBUGLOG(4, "cwksp: clearing tables!");
 
#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    /* We don't do this when the workspace is statically allocated, because
     * when that is the case, we have no capability to hook into the end of the
     * workspace's lifecycle to unpoison the memory.
     */
    if (ws->isStatic == ZSTD_cwksp_dynamic_alloc) {
        size_t size = (BYTE*)ws->tableValidEnd - (BYTE*)ws->objectEnd;
        __asan_poison_memory_region(ws->objectEnd, size);
    }
#endif
 
    ws->tableEnd = ws->objectEnd;
    ZSTD_cwksp_assert_internal_consistency(ws);
}
 
MEM_STATIC void ZSTD_cwksp_clear(ZSTD_cwksp* ws) {
    DEBUGLOG(4, "cwksp: clearing!");
 
#if ZSTD_MEMORY_SANITIZER && !defined (ZSTD_MSAN_DONT_POISON_WORKSPACE)
    /* To validate that the context reuse logic is sound, and that we don't
     * access stuff that this compression hasn't initialized, we re-"poison"
     * the workspace except for the areas in which we expect memory reuse
     * without initialization (objects, valid tables area and init once
     * memory). */
    {
        if((BYTE*)ws->tableValidEnd < (BYTE*)ws->initOnceStart) {
            size_t size = (BYTE*)ws->initOnceStart - (BYTE*)ws->tableValidEnd;
            __msan_poison(ws->tableValidEnd, size);
        }
    }
#endif
 
#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    /* We don't do this when the workspace is statically allocated, because
     * when that is the case, we have no capability to hook into the end of the
     * workspace's lifecycle to unpoison the memory.
     */
    if (ws->isStatic == ZSTD_cwksp_dynamic_alloc) {
        size_t size = (BYTE*)ws->workspaceEnd - (BYTE*)ws->objectEnd;
        __asan_poison_memory_region(ws->objectEnd, size);
    }
#endif
 
    ws->tableEnd = ws->objectEnd;
    ws->allocStart = ZSTD_cwksp_initialAllocStart(ws);
    ws->allocFailed = 0;
    if (ws->phase > ZSTD_cwksp_alloc_aligned_init_once) {
        ws->phase = ZSTD_cwksp_alloc_aligned_init_once;
    }
    ZSTD_cwksp_assert_internal_consistency(ws);
}
 
MEM_STATIC size_t ZSTD_cwksp_sizeof(const ZSTD_cwksp* ws) {
    return (size_t)((BYTE*)ws->workspaceEnd - (BYTE*)ws->workspace);
}
 
MEM_STATIC size_t ZSTD_cwksp_used(const ZSTD_cwksp* ws) {
    return (size_t)((BYTE*)ws->tableEnd - (BYTE*)ws->workspace)
         + (size_t)((BYTE*)ws->workspaceEnd - (BYTE*)ws->allocStart);
}
 
MEM_STATIC void ZSTD_cwksp_init(ZSTD_cwksp* ws, void* start, size_t size, ZSTD_cwksp_static_alloc_e isStatic) {
    DEBUGLOG(4, "cwksp: init'ing workspace with %zd bytes", size);
    assert(((size_t)start & (sizeof(void*)-1)) == 0); /* ensure correct alignment */
    ws->workspace = start;
    ws->workspaceEnd = (BYTE*)start + size;
    ws->objectEnd = ws->workspace;
    ws->tableValidEnd = ws->objectEnd;
    ws->initOnceStart = ZSTD_cwksp_initialAllocStart(ws);
    ws->phase = ZSTD_cwksp_alloc_objects;
    ws->isStatic = isStatic;
    ZSTD_cwksp_clear(ws);
    ws->workspaceOversizedDuration = 0;
    ZSTD_cwksp_assert_internal_consistency(ws);
}
 
MEM_STATIC size_t ZSTD_cwksp_create(ZSTD_cwksp* ws, size_t size, ZSTD_customMem customMem) {
    void* workspace = ZSTD_customMalloc(size, customMem);
    DEBUGLOG(4, "cwksp: creating new workspace with %zd bytes", size);
    RETURN_ERROR_IF(workspace == NULL, memory_allocation, "NULL pointer!");
    ZSTD_cwksp_init(ws, workspace, size, ZSTD_cwksp_dynamic_alloc);
    return 0;
}
 
MEM_STATIC void ZSTD_cwksp_free(ZSTD_cwksp* ws, ZSTD_customMem customMem) {
    void *ptr = ws->workspace;
    DEBUGLOG(4, "cwksp: freeing workspace");
#if ZSTD_MEMORY_SANITIZER && !defined(ZSTD_MSAN_DONT_POISON_WORKSPACE)
    if (ptr != NULL && customMem.customFree != NULL) {
        __msan_unpoison(ptr, ZSTD_cwksp_sizeof(ws));
    }
#endif
    ZSTD_memset(ws, 0, sizeof(ZSTD_cwksp));
    ZSTD_customFree(ptr, customMem);
}
 
MEM_STATIC void ZSTD_cwksp_move(ZSTD_cwksp* dst, ZSTD_cwksp* src) {
    *dst = *src;
    ZSTD_memset(src, 0, sizeof(ZSTD_cwksp));
}
 
MEM_STATIC int ZSTD_cwksp_reserve_failed(const ZSTD_cwksp* ws) {
    return ws->allocFailed;
}
 
/*-*************************************
*  Functions Checking Free Space
***************************************/
 
/* ZSTD_alignmentSpaceWithinBounds() :
 * Returns if the estimated space needed for a wksp is within an acceptable limit of the
 * actual amount of space used.
 */
MEM_STATIC int ZSTD_cwksp_estimated_space_within_bounds(const ZSTD_cwksp *const ws, size_t const estimatedSpace) {
    /* We have an alignment space between objects and tables between tables and buffers, so we can have up to twice
     * the alignment bytes difference between estimation and actual usage */
    return (estimatedSpace - ZSTD_cwksp_slack_space_required()) <= ZSTD_cwksp_used(ws) &&
           ZSTD_cwksp_used(ws) <= estimatedSpace;
}
 
 
MEM_STATIC size_t ZSTD_cwksp_available_space(ZSTD_cwksp* ws) {
    return (size_t)((BYTE*)ws->allocStart - (BYTE*)ws->tableEnd);
}
 
MEM_STATIC int ZSTD_cwksp_check_available(ZSTD_cwksp* ws, size_t additionalNeededSpace) {
    return ZSTD_cwksp_available_space(ws) >= additionalNeededSpace;
}
 
MEM_STATIC int ZSTD_cwksp_check_too_large(ZSTD_cwksp* ws, size_t additionalNeededSpace) {
    return ZSTD_cwksp_check_available(
        ws, additionalNeededSpace * ZSTD_WORKSPACETOOLARGE_FACTOR);
}
 
MEM_STATIC int ZSTD_cwksp_check_wasteful(ZSTD_cwksp* ws, size_t additionalNeededSpace) {
    return ZSTD_cwksp_check_too_large(ws, additionalNeededSpace)
        && ws->workspaceOversizedDuration > ZSTD_WORKSPACETOOLARGE_MAXDURATION;
}
 
MEM_STATIC void ZSTD_cwksp_bump_oversized_duration(
        ZSTD_cwksp* ws, size_t additionalNeededSpace) {
    if (ZSTD_cwksp_check_too_large(ws, additionalNeededSpace)) {
        ws->workspaceOversizedDuration++;
    } else {
        ws->workspaceOversizedDuration = 0;
    }
}
 
#if defined (__cplusplus)
}
#endif
 
#endif /* ZSTD_CWKSP_H */