/******************************************************************************

 *

 * Project:  Common Portability Library

 * Purpose:  Simple implementation of POSIX VSI functions.

 * Author:   Frank Warmerdam, warmerdam@pobox.com

 *

 ******************************************************************************

 * Copyright (c) 1998, Frank Warmerdam

 * Copyright (c) 2008-2012, Even Rouault <even dot rouault at spatialys.com>

 *

 * SPDX-License-Identifier: MIT

 ****************************************************************************

 *

 * NB: Note that in wrappers we are always saving the error state (errno

 * variable) to avoid side effects during debug prints or other possible

 * standard function calls (error states will be overwritten after such

 * a call).

 *

 ****************************************************************************/

// Must be done before including cpl_port.h

// We need __MSVCRT_VERSION__ >= 0x0700 to have "_aligned_malloc"

// Latest versions of mingw32 define it, but with older ones,

// we need to define it manually.

#if defined(__MINGW32__)

#include <windows.h>

#ifndef __MSVCRT_VERSION__

#define __MSVCRT_VERSION__ 0x0700

#endif

#endif

#include "cpl_port.h"

#include "cpl_vsi.h"

#include <algorithm>

#include <cerrno>

#include <cstdarg>

#include <cstddef>

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <ctime>

#include <limits>

#if HAVE_SYS_STAT_H

#include <sys/stat.h>

#endif

#if HAVE_GETRLIMIT

#include <sys/time.h>

#include <sys/resource.h>

#endif

#include "cpl_config.h"

#include "cpl_error.h"

#include "cpl_string.h"

#ifdef _WIN32

#include <malloc.h>  // For _aligned_malloc

#endif

// Uncomment to check consistent usage of VSIMalloc(), VSIRealloc(),

// VSICalloc(), VSIFree(), VSIStrdup().

// #define DEBUG_VSIMALLOC

// Uncomment to compute memory usage statistics.

// DEBUG_VSIMALLOC must also be defined.

// #define DEBUG_VSIMALLOC_STATS

// Highly experimental, and likely buggy. Do not use, except for fixing it!

// DEBUG_VSIMALLOC must also be defined.

// #define DEBUG_VSIMALLOC_MPROTECT

#ifdef DEBUG_VSIMALLOC_MPROTECT

#include <sys/mman.h>

#endif

// Uncomment to print every memory allocation or deallocation.

// DEBUG_VSIMALLOC must also be defined.

// #define DEBUG_VSIMALLOC_VERBOSE

// Number of bytes of the malloc/calloc/free that triggers a debug trace.

// Can be 0 for all allocs.

#define THRESHOLD_PRINT 10000

// Uncomment to print GDAL block cache use.

// Only used if DEBUG_VSIMALLOC_VERBOSE is enabled.

// #define DEBUG_BLOCK_CACHE_USE

#ifdef DEBUG_BLOCK_CACHE_USE

extern "C" GIntBig CPL_DLL CPL_STDCALL GDALGetCacheUsed64(void);

#endif

/* Unix or Windows NT/2000/XP */

#if !defined(_WIN32)

#include <unistd.h>

#else

#include <io.h>

#include <fcntl.h>

#include <direct.h>

#endif

/************************************************************************/

/*                              VSIFOpen()                              */

/************************************************************************/

FILE *VSIFOpen(const char *pszFilename, const char *pszAccess)

{

#if defined(_WIN32)

    FILE *fp = nullptr;

    if (CPLTestBool(CPLGetConfigOption("GDAL_FILENAME_IS_UTF8", "YES")))

    {

        wchar_t *pwszFilename =

            CPLRecodeToWChar(pszFilename, CPL_ENC_UTF8, CPL_ENC_UCS2);

        wchar_t *pwszAccess =

            CPLRecodeToWChar(pszAccess, CPL_ENC_UTF8, CPL_ENC_UCS2);

        fp = _wfopen(pwszFilename, pwszAccess);

        CPLFree(pwszFilename);

        CPLFree(pwszAccess);

    }

    else

    {

        // Are the casts really necessary?

        fp = fopen(const_cast<char *>(pszFilename),

                   const_cast<char *>(pszAccess));

    }

#else

    FILE *fp = fopen(pszFilename, pszAccess);

#endif

#ifdef VSI_DEBUG

    // Capture the error from fopen to avoid being overwritten by errors

    // from VSIDebug3.

    const int nError = errno;

    VSIDebug3("VSIFOpen(%s,%s) = %p", pszFilename, pszAccess, fp);

    errno = nError;

#endif

    return fp;

}

/************************************************************************/

/*                             VSIFClose()                              */

/************************************************************************/

int VSIFClose(FILE *fp)

{

    VSIDebug1("VSIClose(%p)", fp);

    return fclose(fp);

}

/************************************************************************/

/*                              VSIFSeek()                              */

/************************************************************************/

int VSIFSeek(FILE *fp, long nOffset, int nWhence)

{

#ifdef DEBUG

    // To workaround Coverity strange warning about potential negative seek

    // CID 1340084 when called from dgnwrite.cpp.

    if (nWhence == SEEK_SET && nOffset < 0)

        return -1;

#endif

    int nResult = fseek(fp, nOffset, nWhence);

#ifdef VSI_DEBUG

    // Capture the error from fseek to avoid being overwritten by errors

    // from VSIDebug.

    const int nError = errno;

    if (nWhence == SEEK_SET)

    {

        VSIDebug3("VSIFSeek(%p,%ld,SEEK_SET) = %d", fp, nOffset, nResult);

    }

    else if (nWhence == SEEK_END)

    {

        VSIDebug3("VSIFSeek(%p,%ld,SEEK_END) = %d", fp, nOffset, nResult);

    }

    else if (nWhence == SEEK_CUR)

    {

        VSIDebug3("VSIFSeek(%p,%ld,SEEK_CUR) = %d", fp, nOffset, nResult);

    }

    else

    {

        VSIDebug4("VSIFSeek(%p,%ld,%d-Unknown) = %d", fp, nOffset, nWhence,

                  nResult);

    }

    errno = nError;

#endif

    return nResult;

}

/************************************************************************/

/*                              VSIFTell()                              */

/************************************************************************/

long VSIFTell(FILE *fp)

{

    const long nOffset = ftell(fp);

#ifdef VSI_DEBUG

    // Capture the error from ftell to avoid being overwritten by errors

    // from VSIDebug.

    const int nError = errno;

    VSIDebug2("VSIFTell(%p) = %ld", fp, nOffset);

    errno = nError;

#endif

    return nOffset;

}

/************************************************************************/

/*                             VSIRewind()                              */

/************************************************************************/

void VSIRewind(FILE *fp)

{

    VSIDebug1("VSIRewind(%p)", fp);

    rewind(fp);

#ifdef VSI_DEBUG

    // Capture the error rewind ftell to avoid being overwritten by errors

    // from VSIDebug.

    const int nError = errno;

    VSIDebug2("VSIRewind(%p) errno = %d", fp, nError);

    errno = nError;

#endif

}

/************************************************************************/

/*                              VSIFRead()                              */

/************************************************************************/

size_t VSIFRead(void *pBuffer, size_t nSize, size_t nCount, FILE *fp)

{

    const size_t nResult = fread(pBuffer, nSize, nCount, fp);

#ifdef VSI_DEBUG

    // Capture the error from fread to avoid being overwritten by errors

    // from VSIDebug.

    const int nError = errno;

    VSIDebug4("VSIFRead(%p,%ld,%ld) = %ld", fp, static_cast<long>(nSize),

              static_cast<long>(nCount), static_cast<long>(nResult));

    errno = nError;

#endif

    return nResult;

}

/************************************************************************/

/*                             VSIFWrite()                              */

/************************************************************************/

size_t VSIFWrite(const void *pBuffer, size_t nSize, size_t nCount, FILE *fp)

{

    const size_t nResult = fwrite(pBuffer, nSize, nCount, fp);

#ifdef VSI_DEBUG

    // Capture the error from fwrite to avoid being overwritten by errors

    // from VSIDebug.

    const int nError = errno;

    VSIDebug4("VSIFWrite(%p,%ld,%ld) = %ld", fp, static_cast<long>(nSize),

              static_cast<long>(nCount), static_cast<long>(nResult));

    errno = nError;

#endif

    return nResult;

}

/************************************************************************/

/*                             VSIFFlush()                              */

/************************************************************************/

void VSIFFlush(FILE *fp)

{

#ifdef VSI_DEBUG

    VSIDebug1("VSIFFlush(%p)", fp);

    const int result =

#endif

        fflush(fp);

#ifdef VSI_DEBUG

    // Capture the error rewind ftell to avoid being overwritten by errors

    // from VSIDebug.

    const int nError = errno;

    VSIDebug2("VSIRewind(%p) errno = %d", fp, nError);

    if (result != 0)

    {

        CPLError(CE_Failure, CPLE_FileIO, "Flush failed.  errno = %d", nError);

    }

    errno = nError;

#endif

}

/************************************************************************/

/*                              VSIFGets()                              */

/************************************************************************/

char *VSIFGets(char *pszBuffer, int nBufferSize, FILE *fp)

{

    return fgets(pszBuffer, nBufferSize, fp);

}

/************************************************************************/

/*                              VSIFGetc()                              */

/************************************************************************/

int VSIFGetc(FILE *fp)

{

    return fgetc(fp);

}

/************************************************************************/

/*                             VSIUngetc()                              */

/************************************************************************/

int VSIUngetc(int c, FILE *fp)

{

    return ungetc(c, fp);

}

/************************************************************************/

/*                             VSIFPrintf()                             */

/*                                                                      */

/*      This is a little more complicated than just calling             */

/*      fprintf() because of the variable arguments.  Instead we        */

/*      have to use vfprintf().                                         */

/************************************************************************/

int VSIFPrintf(FILE *fp, CPL_FORMAT_STRING(const char *pszFormat), ...)

{

    va_list args;

    va_start(args, pszFormat);

    const int nReturn = vfprintf(fp, pszFormat, args);

    va_end(args);

    return nReturn;

}

/************************************************************************/

/*                              VSIFEof()                               */

/************************************************************************/

int VSIFEof(FILE *fp)

{

    return feof(fp);

}

/************************************************************************/

/*                              VSIFPuts()                              */

/************************************************************************/

int VSIFPuts(const char *pszString, FILE *fp)

{

    return fputs(pszString, fp);

}

/************************************************************************/

/*                              VSIFPutc()                              */

/************************************************************************/

int VSIFPutc(int nChar, FILE *fp)

{

    return fputc(nChar, fp);

}

#ifdef DEBUG_VSIMALLOC_STATS

#include "cpl_multiproc.h"

static CPLMutex *hMemStatMutex = nullptr;

static size_t nCurrentTotalAllocs = 0;

static size_t nMaxTotalAllocs = 0;

static GUIntBig nVSIMallocs = 0;

static GUIntBig nVSICallocs = 0;

static GUIntBig nVSIReallocs = 0;

static GUIntBig nVSIFrees = 0;

/************************************************************************/

/*                         VSIShowMemStats()                            */

/************************************************************************/

void VSIShowMemStats();

void VSIShowMemStats()

{

    char *pszShowMemStats = getenv("CPL_SHOW_MEM_STATS");

    if (pszShowMemStats == nullptr || pszShowMemStats[0] == '\0')

        return;

    printf("Current VSI memory usage        : " CPL_FRMT_GUIB " bytes\n", /*ok*/

           static_cast<GUIntBig>(nCurrentTotalAllocs));

    printf("Maximum VSI memory usage        : " CPL_FRMT_GUIB " bytes\n", /*ok*/

           static_cast<GUIntBig>(nMaxTotalAllocs));

    printf("Number of calls to VSIMalloc()  : " CPL_FRMT_GUIB "\n", /*ok*/

           nVSIMallocs);

    printf("Number of calls to VSICalloc()  : " CPL_FRMT_GUIB "\n", /*ok*/

           nVSICallocs);

    printf("Number of calls to VSIRealloc() : " CPL_FRMT_GUIB "\n", /*ok*/

           nVSIReallocs);

    printf("Number of calls to VSIFree()    : " CPL_FRMT_GUIB "\n", /*ok*/

           nVSIFrees);

    printf("VSIMalloc + VSICalloc - VSIFree : " CPL_FRMT_GUIB "\n", /*ok*/

           nVSIMallocs + nVSICallocs - nVSIFrees);

}

#endif

#ifdef DEBUG_VSIMALLOC

static GIntBig nMaxPeakAllocSize = -1;

static GIntBig nMaxCumulAllocSize = -1;

#endif

/************************************************************************/

/*                             VSICalloc()                              */

/************************************************************************/

#ifndef DEBUG_VSIMALLOC

/** Analog of calloc(). Use VSIFree() to free */

void *VSICalloc(size_t nCount, size_t nSize)

{

    // cppcheck-suppress invalidFunctionArg

    return calloc(nCount, nSize);

}

#else  // DEBUG_VSIMALLOC

void *VSICalloc(size_t nCount, size_t nSize)

{

    size_t nMul = nCount * nSize;

    if (nCount != 0 && nMul / nCount != nSize)

    {

        fprintf(stderr, "Overflow in VSICalloc(%d, %d)\n", /*ok*/

                static_cast<int>(nCount), static_cast<int>(nSize));

        return nullptr;

    }

    if (nMaxPeakAllocSize < 0)

    {

        char *pszMaxPeakAllocSize = getenv("CPL_MAX_PEAK_ALLOC_SIZE");

        nMaxPeakAllocSize = pszMaxPeakAllocSize ? atoi(pszMaxPeakAllocSize) : 0;

        char *pszMaxCumulAllocSize = getenv("CPL_MAX_CUMUL_ALLOC_SIZE");

        nMaxCumulAllocSize =

            pszMaxCumulAllocSize ? atoi(pszMaxCumulAllocSize) : 0;

    }

    if (nMaxPeakAllocSize > 0 && static_cast<GIntBig>(nMul) > nMaxPeakAllocSize)

        return nullptr;

#ifdef DEBUG_VSIMALLOC_STATS

    if (nMaxCumulAllocSize > 0 &&

        static_cast<GIntBig>(nCurrentTotalAllocs) + static_cast<GIntBig>(nMul) >

            nMaxCumulAllocSize)

        return nullptr;

#endif

#ifdef DEBUG_VSIMALLOC_MPROTECT

    char *ptr = nullptr;

    const size_t nPageSize = getpagesize();

    const size_t nRequestedSize =

        (3 * sizeof(void *) + nMul + nPageSize - 1) & ~(nPageSize - 1);

    if (nRequestedSize < nMul)

        return nullptr;

    posix_memalign((void **)&ptr, nPageSize, nRequestedSize);

    if (ptr == nullptr)

        return nullptr;

    memset(ptr + 2 * sizeof(void *), 0, nMul);

#else

    const size_t nRequestedSize = 3 * sizeof(void *) + nMul;

    if (nRequestedSize < nMul)

        return nullptr;

    char *ptr = static_cast<char *>(calloc(1, nRequestedSize));

    if (ptr == nullptr)

        return nullptr;

#endif

    ptr[0] = 'V';

    ptr[1] = 'S';

    ptr[2] = 'I';

    ptr[3] = 'M';

    // cppcheck-suppress pointerSize

    memcpy(ptr + sizeof(void *), &nMul, sizeof(void *));

    ptr[2 * sizeof(void *) + nMul + 0] = 'E';

    ptr[2 * sizeof(void *) + nMul + 1] = 'V';

    ptr[2 * sizeof(void *) + nMul + 2] = 'S';

    ptr[2 * sizeof(void *) + nMul + 3] = 'I';

#if defined(DEBUG_VSIMALLOC_STATS) || defined(DEBUG_VSIMALLOC_VERBOSE)

    {

        CPLMutexHolderD(&hMemStatMutex);

#ifdef DEBUG_VSIMALLOC_VERBOSE

        if (nMul > THRESHOLD_PRINT)

        {

            fprintf(stderr, /*ok*/

                    "Thread[%p] VSICalloc(%d,%d) = %p"

#ifdef DEBUG_VSIMALLOC_STATS

                    ", current_cumul = " CPL_FRMT_GUIB

#ifdef DEBUG_BLOCK_CACHE_USE

                    ", block_cache_used = " CPL_FRMT_GIB

#endif

                    ", mal+cal-free = %d"

#endif

                    "\n",

                    (void *)CPLGetPID(), static_cast<int>(nCount),

                    static_cast<int>(nSize), ptr + 2 * sizeof(void *)

#ifdef DEBUG_VSIMALLOC_STATS

                                                 ,

                    static_cast<GUIntBig>(nCurrentTotalAllocs + nMul)

#ifdef DEBUG_BLOCK_CACHE_USE

                        ,

                    GDALGetCacheUsed64()

#endif

                        ,

                    static_cast<int>(nVSIMallocs + nVSICallocs - nVSIFrees)

#endif

            );

        }

#endif

#ifdef DEBUG_VSIMALLOC_STATS

        nVSICallocs++;

        if (nMaxTotalAllocs == 0)

            atexit(VSIShowMemStats);

        nCurrentTotalAllocs += nMul;

        if (nCurrentTotalAllocs > nMaxTotalAllocs)

            nMaxTotalAllocs = nCurrentTotalAllocs;

#endif

    }

#endif

    // cppcheck-suppress memleak

    return ptr + 2 * sizeof(void *);

}

#endif  // DEBUG_VSIMALLOC

/************************************************************************/

/*                             VSIMalloc()                              */

/************************************************************************/

#ifndef DEBUG_VSIMALLOC

/** Analog of malloc(). Use VSIFree() to free */

void *VSIMalloc(size_t nSize)

{

    return malloc(nSize);

}

#else  // DEBUG_VSIMALLOC

void *VSIMalloc(size_t nSize)

{

    if (nMaxPeakAllocSize < 0)

    {

        char *pszMaxPeakAllocSize = getenv("CPL_MAX_PEAK_ALLOC_SIZE");

        nMaxPeakAllocSize = pszMaxPeakAllocSize ? atoi(pszMaxPeakAllocSize) : 0;

        char *pszMaxCumulAllocSize = getenv("CPL_MAX_CUMUL_ALLOC_SIZE");

        nMaxCumulAllocSize =

            pszMaxCumulAllocSize ? atoi(pszMaxCumulAllocSize) : 0;

    }

    if (nMaxPeakAllocSize > 0 &&

        static_cast<GIntBig>(nSize) > nMaxPeakAllocSize)

        return nullptr;

#ifdef DEBUG_VSIMALLOC_STATS

    if (nMaxCumulAllocSize > 0 && static_cast<GIntBig>(nCurrentTotalAllocs) +

                                          static_cast<GIntBig>(nSize) >

                                      nMaxCumulAllocSize)

        return nullptr;

#endif  // DEBUG_VSIMALLOC_STATS

#ifdef DEBUG_VSIMALLOC_MPROTECT

    char *ptr = nullptr;

    const size_t nPageSize = getpagesize();

    const size_t nRequestedSize =

        (3 * sizeof(void *) + nSize + nPageSize - 1) & ~(nPageSize - 1);

    if (nRequestedSize < nSize)

        return nullptr;

    posix_memalign((void **)&ptr, nPageSize, nRequestedSize);

#else

    const size_t nRequestedSize = 3 * sizeof(void *) + nSize;

    if (nRequestedSize < nSize)

        return nullptr;

    char *ptr = static_cast<char *>(malloc(nRequestedSize));

#endif  // DEBUG_VSIMALLOC_MPROTECT

    if (ptr == nullptr)

        return nullptr;

    ptr[0] = 'V';

    ptr[1] = 'S';

    ptr[2] = 'I';

    ptr[3] = 'M';

    // cppcheck-suppress pointerSize

    memcpy(ptr + sizeof(void *), &nSize, sizeof(void *));

    ptr[2 * sizeof(void *) + nSize + 0] = 'E';

    ptr[2 * sizeof(void *) + nSize + 1] = 'V';

    ptr[2 * sizeof(void *) + nSize + 2] = 'S';

    ptr[2 * sizeof(void *) + nSize + 3] = 'I';

#if defined(DEBUG_VSIMALLOC_STATS) || defined(DEBUG_VSIMALLOC_VERBOSE)

    {

        CPLMutexHolderD(&hMemStatMutex);

#ifdef DEBUG_VSIMALLOC_VERBOSE

        if (nSize > THRESHOLD_PRINT)

        {

            fprintf(stderr, /*ok*/

                    "Thread[%p] VSIMalloc(%d) = %p"

#ifdef DEBUG_VSIMALLOC_STATS

                    ", current_cumul = " CPL_FRMT_GUIB

#ifdef DEBUG_BLOCK_CACHE_USE

                    ", block_cache_used = " CPL_FRMT_GIB

#endif

                    ", mal+cal-free = %d"

#endif

                    "\n",

                    (void *)CPLGetPID(), static_cast<int>(nSize),

                    ptr + 2 * sizeof(void *)

#ifdef DEBUG_VSIMALLOC_STATS

                        ,

                    static_cast<GUIntBig>(nCurrentTotalAllocs + nSize)

#ifdef DEBUG_BLOCK_CACHE_USE

                        ,

                    GDALGetCacheUsed64()

#endif

                        ,

                    static_cast<int>(nVSIMallocs + nVSICallocs - nVSIFrees)

#endif

            );

        }

#endif  // DEBUG_VSIMALLOC_VERBOSE

#ifdef DEBUG_VSIMALLOC_STATS

        nVSIMallocs++;

        if (nMaxTotalAllocs == 0)

            atexit(VSIShowMemStats);

        nCurrentTotalAllocs += nSize;

        if (nCurrentTotalAllocs > nMaxTotalAllocs)

            nMaxTotalAllocs = nCurrentTotalAllocs;

#endif  // DEBUG_VSIMALLOC_STATS

    }

#endif  // DEBUG_VSIMALLOC_STATS || DEBUG_VSIMALLOC_VERBOSE

    // cppcheck-suppress memleak

    return ptr + 2 * sizeof(void *);

}

static void VSICheckMarkerBegin(char *ptr)

{

    if (memcmp(ptr, "VSIM", 4) != 0)

    {

        CPLError(CE_Fatal, CPLE_AppDefined,

                 "Inconsistent use of VSI memory allocation primitives "

                 "for %p : %c%c%c%c",

                 ptr, ptr[0], ptr[1], ptr[2], ptr[3]);

    }

}

static void VSICheckMarkerEnd(char *ptr, size_t nEnd)

{

    if (memcmp(ptr + nEnd, "EVSI", 4) != 0)

    {

        CPLError(CE_Fatal, CPLE_AppDefined,

                 "Memory has been written after the end of %p", ptr);

    }

}

#endif  // DEBUG_VSIMALLOC

/************************************************************************/

/*                             VSIRealloc()                             */

/************************************************************************/

/** Analog of realloc(). Use VSIFree() to free.

 *

 * If the pointer is NULL, VSIRealloc is equivalent to VSIMalloc.

 */

void *VSIRealloc(void *pData, size_t nNewSize)

{

#ifdef DEBUG_VSIMALLOC

    if (pData == nullptr)

        return VSIMalloc(nNewSize);

    char *ptr = ((char *)pData) - 2 * sizeof(void *);

    VSICheckMarkerBegin(ptr);

    size_t nOldSize = 0;

    // cppcheck-suppress pointerSize

    memcpy(&nOldSize, ptr + sizeof(void *), sizeof(void *));

    VSICheckMarkerEnd(ptr, 2 * sizeof(void *) + nOldSize);

    if (nMaxPeakAllocSize < 0)

    {

        char *pszMaxPeakAllocSize = getenv("CPL_MAX_PEAK_ALLOC_SIZE");

        nMaxPeakAllocSize = pszMaxPeakAllocSize ? atoi(pszMaxPeakAllocSize) : 0;

    }

    if (nMaxPeakAllocSize > 0 &&

        static_cast<GIntBig>(nNewSize) > nMaxPeakAllocSize)

        return nullptr;

#ifdef DEBUG_VSIMALLOC_STATS

    if (nMaxCumulAllocSize > 0 && static_cast<GIntBig>(nCurrentTotalAllocs) +

                                          static_cast<GIntBig>(nNewSize) -

                                          static_cast<GIntBig>(nOldSize) >

                                      nMaxCumulAllocSize)

        return nullptr;

#endif

    ptr[2 * sizeof(void *) + nOldSize + 0] = 'I';

    ptr[2 * sizeof(void *) + nOldSize + 1] = 'S';

    ptr[2 * sizeof(void *) + nOldSize + 2] = 'V';

    ptr[2 * sizeof(void *) + nOldSize + 3] = 'E';

#ifdef DEBUG_VSIMALLOC_MPROTECT

    char *newptr = nullptr;

    const size_t nPageSize = getpagesize();

    const size_t nRequestedSize =

        (nNewSize + 3 * sizeof(void *) + nPageSize - 1) & ~(nPageSize - 1);

    if (nRequestedSize < nNewSize)

    {

        ptr[2 * sizeof(void *) + nOldSize + 0] = 'E';

        ptr[2 * sizeof(void *) + nOldSize + 1] = 'V';

        ptr[2 * sizeof(void *) + nOldSize + 2] = 'S';

        ptr[2 * sizeof(void *) + nOldSize + 3] = 'I';

        return nullptr;

    }

    posix_memalign((void **)&newptr, nPageSize, nRequestedSize);

    if (newptr == nullptr)

    {

        ptr[2 * sizeof(void *) + nOldSize + 0] = 'E';

        ptr[2 * sizeof(void *) + nOldSize + 1] = 'V';

        ptr[2 * sizeof(void *) + nOldSize + 2] = 'S';

        ptr[2 * sizeof(void *) + nOldSize + 3] = 'I';

        return nullptr;

    }

    memcpy(newptr + 2 * sizeof(void *), pData, nOldSize);

    ptr[0] = 'M';

    ptr[1] = 'I';

    ptr[2] = 'S';

    ptr[3] = 'V';

    free(ptr);

    newptr[0] = 'V';

    newptr[1] = 'S';

    newptr[2] = 'I';

    newptr[3] = 'M';

#else

    const size_t nRequestedSize = 3 * sizeof(void *) + nNewSize;

    if (nRequestedSize < nNewSize)

    {

        ptr[2 * sizeof(void *) + nOldSize + 0] = 'E';

        ptr[2 * sizeof(void *) + nOldSize + 1] = 'V';

        ptr[2 * sizeof(void *) + nOldSize + 2] = 'S';

        ptr[2 * sizeof(void *) + nOldSize + 3] = 'I';

        return nullptr;

    }

    void *newptr = realloc(ptr, nRequestedSize);

    if (newptr == nullptr)

    {

        ptr[2 * sizeof(void *) + nOldSize + 0] = 'E';

        ptr[2 * sizeof(void *) + nOldSize + 1] = 'V';

        ptr[2 * sizeof(void *) + nOldSize + 2] = 'S';

        ptr[2 * sizeof(void *) + nOldSize + 3] = 'I';

        return nullptr;

    }

#endif

    ptr = static_cast<char *>(newptr);

    // cppcheck-suppress pointerSize

    memcpy(ptr + sizeof(void *), &nNewSize, sizeof(void *));

    ptr[2 * sizeof(void *) + nNewSize + 0] = 'E';

    ptr[2 * sizeof(void *) + nNewSize + 1] = 'V';

    ptr[2 * sizeof(void *) + nNewSize + 2] = 'S';

    ptr[2 * sizeof(void *) + nNewSize + 3] = 'I';

#if defined(DEBUG_VSIMALLOC_STATS) || defined(DEBUG_VSIMALLOC_VERBOSE)

    {

        CPLMutexHolderD(&hMemStatMutex);

#ifdef DEBUG_VSIMALLOC_VERBOSE

        if (nNewSize > THRESHOLD_PRINT)

        {

            fprintf(

                stderr,

                "Thread[%p] VSIRealloc(%p, %d) = %p" /*ok*/

#ifdef DEBUG_VSIMALLOC_STATS

                ", current_cumul = " CPL_FRMT_GUIB

#ifdef DEBUG_BLOCK_CACHE_USE

                ", block_cache_used = " CPL_FRMT_GIB

#endif

                ", mal+cal-free = %d"

#endif

                "\n",

                (void *)CPLGetPID(), pData, static_cast<int>(nNewSize),

                ptr + 2 * sizeof(void *)

#ifdef DEBUG_VSIMALLOC_STATS

                    ,

                static_cast<GUIntBig>(nCurrentTotalAllocs - nOldSize + nNewSize)

#ifdef DEBUG_BLOCK_CACHE_USE

                    ,

                GDALGetCacheUsed64()

#endif

                    ,

                static_cast<int>(nVSIMallocs + nVSICallocs - nVSIFrees)

#endif

            );

        }

#endif

#ifdef DEBUG_VSIMALLOC_STATS

        nVSIReallocs++;

        nCurrentTotalAllocs -= nOldSize;

        nCurrentTotalAllocs += nNewSize;

        if (nCurrentTotalAllocs > nMaxTotalAllocs)

            nMaxTotalAllocs = nCurrentTotalAllocs;

#endif

    }

#endif

    return ptr + 2 * sizeof(void *);

#else

    return realloc(pData, nNewSize);

#endif

}

/************************************************************************/

/*                              VSIFree()                               */

/************************************************************************/

/** Analog of free() for data allocated with VSIMalloc(), VSICalloc(),

 * VSIRealloc().

 *

 * It is not an error to call VSIFree with a NULL pointer, and it will

 * have no effect.

 */

void VSIFree(void *pData)

{

#ifdef DEBUG_VSIMALLOC

    if (pData == nullptr)

        return;

    char *ptr = ((char *)pData) - 2 * sizeof(void *);

    VSICheckMarkerBegin(ptr);

    size_t nOldSize = 0;

    // cppcheck-suppress pointerSize

    memcpy(&nOldSize, ptr + sizeof(void *), sizeof(void *));

    VSICheckMarkerEnd(ptr, 2 * sizeof(void *) + nOldSize);

    ptr[0] = 'M';

    ptr[1] = 'I';

    ptr[2] = 'S';

    ptr[3] = 'V';

    ptr[2 * sizeof(void *) + nOldSize + 0] = 'I';

    ptr[2 * sizeof(void *) + nOldSize + 1] = 'S';

    ptr[2 * sizeof(void *) + nOldSize + 2] = 'V';

    ptr[2 * sizeof(void *) + nOldSize + 3] = 'E';

#if defined(DEBUG_VSIMALLOC_STATS) || defined(DEBUG_VSIMALLOC_VERBOSE)

    {

        CPLMutexHolderD(&hMemStatMutex);

#ifdef DEBUG_VSIMALLOC_VERBOSE

        if (nOldSize > THRESHOLD_PRINT)

        {

            fprintf(stderr, "Thread[%p] VSIFree(%p, (%d bytes))\n", /*ok*/

                    (void *)CPLGetPID(), pData, static_cast<int>(nOldSize));

        }

#endif

#ifdef DEBUG_VSIMALLOC_STATS

        nVSIFrees++;

        nCurrentTotalAllocs -= nOldSize;

#endif

    }

#endif

#ifdef DEBUG_VSIMALLOC_MPROTECT

    mprotect(ptr, nOldSize + 2 * sizeof(void *), PROT_NONE);

#else

    free(ptr);

#endif

#else

    if (pData != nullptr)

        free(pData);

#endif

}

/************************************************************************/

/*                      VSIMallocAligned()                              */

/************************************************************************/

/** Allocates a buffer with an alignment constraint.

 *

 * The return value must be freed with VSIFreeAligned().

 *

 * @param nAlignment Must be a power of 2, multiple of sizeof(void*), and

 *                   lesser than 256.

 * @param nSize Size of the buffer to allocate.

 * @return a buffer aligned on nAlignment and of size nSize, or NULL

 * @since GDAL 2.2

 */

void *VSIMallocAligned(size_t nAlignment, size_t nSize)

{

    // In particular for posix_memalign() where behavior when passing

    // nSize == 0 is technically implementation defined (Valgrind complains),

    // so let's always return NULL.

    if (nSize == 0)

        return nullptr;

#if defined(HAVE_POSIX_MEMALIGN) && !defined(DEBUG_VSIMALLOC)

    void *pRet = nullptr;

    if (posix_memalign(&pRet, nAlignment, nSize) != 0)

    {

        pRet = nullptr;

    }

    return pRet;

#elif defined(_WIN32) && !defined(DEBUG_VSIMALLOC)

    return _aligned_malloc(nSize, nAlignment);

#else

    // Check constraints on alignment.

    if (nAlignment < sizeof(void *) || nAlignment >= 256 ||

        (nAlignment & (nAlignment - 1)) != 0)

        return nullptr;

    // Detect overflow.

    if (nSize + nAlignment < nSize)

        return nullptr;

    GByte *pabyData = static_cast<GByte *>(VSIMalloc(nSize + nAlignment));

    if (pabyData == nullptr)

        return nullptr;

    size_t nShift =

        nAlignment - (reinterpret_cast<size_t>(pabyData) % nAlignment);

    GByte *pabyAligned = pabyData + nShift;

    // Guaranteed to fit on a byte since nAlignment < 256.

    pabyAligned[-1] = static_cast<GByte>(nShift);

    return pabyAligned;

#endif

}

/************************************************************************/

/*                     VSIMallocAlignedAuto()                           */

/************************************************************************/

/** Allocates a buffer with an alignment constraint such that it can be

 * used by the most demanding vector instruction set on that platform.

 *

 * The return value must be freed with VSIFreeAligned().

 *

 * @param nSize Size of the buffer to allocate.

 * @return an aligned buffer of size nSize, or NULL

 * @since GDAL 2.2

 */

void *VSIMallocAlignedAuto(size_t nSize)

{

    // We could potentially dynamically detect the capability of the CPU

    // but to simplify use 64 for AVX512 requirements (we use only AVX256

    // currently).

    return VSIMallocAligned(64, nSize);

}

/************************************************************************/

/*                        VSIMallocAlignedAutoVerbose()                 */

/************************************************************************/

/** See VSIMallocAlignedAuto() */

void *VSIMallocAlignedAutoVerbose(size_t nSize, const char *pszFile, int nLine)

{

    void *pRet = VSIMallocAlignedAuto(nSize);

    if (pRet == nullptr && nSize != 0)

    {

        CPLError(CE_Failure, CPLE_OutOfMemory,

                 "%s, %d: cannot allocate " CPL_FRMT_GUIB " bytes",

                 pszFile ? pszFile : "(unknown file)", nLine,

                 static_cast<GUIntBig>(nSize));

    }

    return pRet;

}

/************************************************************************/

/*                        VSIFreeAligned()                              */

/************************************************************************/

/** Free a buffer allocated with VSIMallocAligned().

 *

 * @param ptr Buffer to free.

 * @since GDAL 2.2

 */

void VSIFreeAligned(void *ptr)

{

#if defined(HAVE_POSIX_MEMALIGN) && !defined(DEBUG_VSIMALLOC)

    free(ptr);

#elif defined(_WIN32) && !defined(DEBUG_VSIMALLOC)

    _aligned_free(ptr);

#else

    if (ptr == nullptr)

        return;

    GByte *pabyAligned = static_cast<GByte *>(ptr);

    size_t nShift = pabyAligned[-1];

    VSIFree(pabyAligned - nShift);

#endif

}

/************************************************************************/

/*                             VSIStrdup()                              */

/************************************************************************/

/** Analog of strdup(). Use VSIFree() to free */

char *VSIStrdup(const char *pszString)

{

    const size_t nSize = strlen(pszString) + 1;

    char *ptr = static_cast<char *>(VSIMalloc(nSize));

    if (ptr == nullptr)

        return nullptr;

    memcpy(ptr, pszString, nSize);

    return ptr;

}

/************************************************************************/

/*                          VSICheckMul2()                              */

/************************************************************************/

CPL_NOSANITIZE_UNSIGNED_INT_OVERFLOW

static size_t VSICheckMul2(size_t mul1, size_t mul2, bool *pbOverflowFlag,

                           const char *pszFile, int nLine)

{

    const size_t res = mul1 * mul2;

    if (mul1 != 0)

    {

        if (res / mul1 == mul2)

        {

            if (pbOverflowFlag)

                *pbOverflowFlag = FALSE;

            return res;

        }

        else

        {

            if (pbOverflowFlag)

                *pbOverflowFlag = TRUE;

            CPLError(CE_Failure, CPLE_OutOfMemory,

                     "%s: %d: Multiplication overflow : " CPL_FRMT_GUIB

                     " * " CPL_FRMT_GUIB,

                     pszFile ? pszFile : "(unknown file)", nLine,

                     static_cast<GUIntBig>(mul1), static_cast<GUIntBig>(mul2));

        }

    }

    else

    {

        if (pbOverflowFlag)

            *pbOverflowFlag = FALSE;

    }

    return 0;

}

/************************************************************************/

/*                          VSICheckMul3()                              */

/************************************************************************/

CPL_NOSANITIZE_UNSIGNED_INT_OVERFLOW

static size_t VSICheckMul3(size_t mul1, size_t mul2, size_t mul3,

                           bool *pbOverflowFlag, const char *pszFile, int nLine)

{

    if (mul1 != 0)

    {

        const size_t res = mul1 * mul2;

        if (res / mul1 == mul2)

        {

            const size_t res2 = res * mul3;

            if (mul3 != 0)

            {

                if (res2 / mul3 == res)

                {

                    if (pbOverflowFlag)

                        *pbOverflowFlag = false;

                    return res2;

                }

                else

                {

                    if (pbOverflowFlag)

                        *pbOverflowFlag = true;

                    CPLError(CE_Failure, CPLE_OutOfMemory,

                             "%s: %d: Multiplication overflow : " CPL_FRMT_GUIB

                             " * " CPL_FRMT_GUIB " * " CPL_FRMT_GUIB,

                             pszFile ? pszFile : "(unknown file)", nLine,

                             static_cast<GUIntBig>(mul1),