cpl_vsil_curl_streaming.cpp

/******************************************************************************
 *
 * Project:  CPL - Common Portability Library
 * Purpose:  Implement VSI large file api for HTTP/FTP files in streaming mode
 * Author:   Even Rouault <even dot rouault at spatialys.com>
 *
 ******************************************************************************
 * Copyright (c) 2012-2015, Even Rouault <even dot rouault at spatialys.com>
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/

#include "cpl_port.h"
#include "cpl_vsi.h"
#include "cpl_vsi_virtual.h"
#include "cpl_vsil_curl_class.h"

#include <algorithm>
#include <map>

#include "cpl_aws.h"
#include "cpl_google_cloud.h"
#include "cpl_azure.h"
#include "cpl_alibaba_oss.h"
#include "cpl_swift.h"
#include "cpl_hash_set.h"
#include "cpl_http.h"
#include "cpl_multiproc.h"
#include "cpl_string.h"
#include "cpl_time.h"

#if !defined(HAVE_CURL) || defined(CPL_MULTIPROC_STUB)

void VSIInstallCurlStreamingFileHandler(void)
{
    // Not supported.
}

void VSIInstallS3StreamingFileHandler(void)
{
    // Not supported.
}

void VSIInstallGSStreamingFileHandler(void)
{
    // Not supported.
}

void VSIInstallAzureStreamingFileHandler(void)
{
    // Not supported
}

void VSIInstallOSSStreamingFileHandler(void)
{
    // Not supported
}

void VSIInstallSwiftStreamingFileHandler(void)
{
    // Not supported
}

#ifdef HAVE_CURL
void VSICurlStreamingClearCache(void)
{
    // Not supported
}
#endif

#else

//! @cond Doxygen_Suppress

#include <curl/curl.h>

#define ENABLE_DEBUG 0

#define N_MAX_REGIONS 10

#define BKGND_BUFFER_SIZE (1024 * 1024)

#define unchecked_curl_easy_setopt(handle, opt, param)                         \
    CPL_IGNORE_RET_VAL(curl_easy_setopt(handle, opt, param))

/************************************************************************/
/*                               RingBuffer                             */
/************************************************************************/

class RingBuffer
{
    CPL_DISALLOW_COPY_ASSIGN(RingBuffer)

    GByte *pabyBuffer = nullptr;
    size_t nCapacity = 0;
    size_t nOffset = 0;
    size_t nLength = 0;

  public:
    explicit RingBuffer(size_t nCapacity = BKGND_BUFFER_SIZE);
    ~RingBuffer();

    size_t GetCapacity() const
    {
        return nCapacity;
    }

    size_t GetSize() const
    {
        return nLength;
    }

    void Reset();
    void Write(void *pBuffer, size_t nSize);
    void Read(void *pBuffer, size_t nSize);
};

RingBuffer::RingBuffer(size_t nCapacityIn)
    : pabyBuffer(static_cast<GByte *>(CPLMalloc(nCapacityIn))),
      nCapacity(nCapacityIn)
{
}

RingBuffer::~RingBuffer()
{
    CPLFree(pabyBuffer);
}

void RingBuffer::Reset()
{
    nOffset = 0;
    nLength = 0;
}

void RingBuffer::Write(void *pBuffer, size_t nSize)
{
    CPLAssert(nLength + nSize <= nCapacity);

    const size_t nEndOffset = (nOffset + nLength) % nCapacity;
    const size_t nSz = std::min(nSize, nCapacity - nEndOffset);
    memcpy(pabyBuffer + nEndOffset, pBuffer, nSz);
    if (nSz < nSize)
        memcpy(pabyBuffer, static_cast<GByte *>(pBuffer) + nSz, nSize - nSz);

    nLength += nSize;
}

void RingBuffer::Read(void *pBuffer, size_t nSize)
{
    CPLAssert(nSize <= nLength);

    if (pBuffer)
    {
        const size_t nSz = std::min(nSize, nCapacity - nOffset);
        memcpy(pBuffer, pabyBuffer + nOffset, nSz);
        if (nSz < nSize)
            memcpy(static_cast<GByte *>(pBuffer) + nSz, pabyBuffer,
                   nSize - nSz);
    }

    nOffset = (nOffset + nSize) % nCapacity;
    nLength -= nSize;
}

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

namespace
{

typedef struct
{
    char *pBuffer;
    size_t nSize;
    int bIsHTTP;
    int bIsInHeader;
    int nHTTPCode;
    int bDownloadHeaderOnly;
} WriteFuncStructStreaming;

}  // namespace

namespace cpl
{

/************************************************************************/
/*                       VSICurlStreamingFSHandler                      */
/************************************************************************/

class VSICurlStreamingHandle;

class VSICurlStreamingFSHandler : public VSIFilesystemHandler
{
    CPL_DISALLOW_COPY_ASSIGN(VSICurlStreamingFSHandler)

    // LRU cache that just keeps in memory if this file system handler is
    // spposed to know the file properties of a file. The actual cache is a
    // shared one among all network file systems.
    // The aim of that design is that invalidating /vsis3/foo results in
    // /vsis3_streaming/foo to be invalidated as well.
    lru11::Cache<std::string, bool> oCacheFileProp;

  protected:
    CPLMutex *hMutex = nullptr;

    virtual VSICurlStreamingHandle *CreateFileHandle(const char *pszFilename,
                                                     const char *pszURL);

    virtual std::string GetNonStreamingPrefix() const
    {
        return "/vsicurl/";
    }

  public:
    VSICurlStreamingFSHandler();
    virtual ~VSICurlStreamingFSHandler();

    virtual VSIVirtualHandle *Open(const char *pszFilename,
                                   const char *pszAccess, bool bSetError,
                                   CSLConstList /* papszOptions */) override;
    virtual int Stat(const char *pszFilename, VSIStatBufL *pStatBuf,
                     int nFlags) override;

    virtual CPLString GetFSPrefix() const
    {
        return "/vsicurl_streaming/";
    }

    std::string
    GetNonStreamingFilename(const std::string &osFilename) const override;

    const char *GetActualURL(const char *pszFilename) override;

    const char *GetOptions() override
    {
        return VSIGetFileSystemOptions("/vsicurl/");
    }

    void AcquireMutex();
    void ReleaseMutex();

    bool GetCachedFileProp(const char *pszURL, FileProp &oFileProp);
    void SetCachedFileProp(const char *pszURL, FileProp &oFileProp);

    virtual void ClearCache();
};

/************************************************************************/
/*                        VSICurlStreamingHandle                        */
/************************************************************************/

class VSICurlStreamingHandle : public VSIVirtualHandle
{
    CPL_DISALLOW_COPY_ASSIGN(VSICurlStreamingHandle)

  protected:
    VSICurlStreamingFSHandler *m_poFS = nullptr;
    CPLStringList m_aosHTTPOptions{};
    const CPLHTTPRetryParameters m_oRetryParameters;

  private:
    char *m_pszURL = nullptr;

#ifdef notdef
    unsigned int nRecomputedChecksumOfFirst1024Bytes = 0;
#endif
    vsi_l_offset curOffset = 0;
    vsi_l_offset fileSize = 0;
    bool bHasComputedFileSize = false;
    ExistStatus eExists = EXIST_UNKNOWN;
    bool bIsDirectory = false;

    bool bCanTrustCandidateFileSize = true;
    bool bHasCandidateFileSize = false;
    vsi_l_offset nCandidateFileSize = 0;

    bool bEOF = false;
    bool m_bError = false;

    size_t nCachedSize = 0;
    GByte *pCachedData = nullptr;

    volatile int bDownloadInProgress = FALSE;
    volatile int bDownloadStopped = FALSE;
    volatile int bAskDownloadEnd = FALSE;
    vsi_l_offset nRingBufferFileOffset = 0;
    CPLJoinableThread *hThread = nullptr;
    CPLMutex *hRingBufferMutex = nullptr;
    CPLCond *hCondProducer = nullptr;
    CPLCond *hCondConsumer = nullptr;
    RingBuffer oRingBuffer{};
    void StartDownload();
    void StopDownload();
    void PutRingBufferInCache();

    GByte *pabyHeaderData = nullptr;
    size_t nHeaderSize = 0;
    vsi_l_offset nBodySize = 0;
    int nHTTPCode = 0;
    char m_szCurlErrBuf[CURL_ERROR_SIZE + 1];
    bool m_bErrorOccurredInThread = false;

    void AcquireMutex();
    void ReleaseMutex();

    void AddRegion(vsi_l_offset nFileOffsetStart, size_t nSize, GByte *pData);

  protected:
    virtual struct curl_slist *
    GetCurlHeaders(const CPLString &,
                   const struct curl_slist * /* psExistingHeaders */)
    {
        return nullptr;
    }

    virtual bool StopReceivingBytesOnError()
    {
        return true;
    }

    virtual bool CanRestartOnError(const char * /*pszErrorMsg*/,
                                   const char * /*pszHeaders*/,
                                   bool /*bSetError*/)
    {
        return false;
    }

    virtual bool InterpretRedirect()
    {
        return true;
    }

    void SetURL(const char *pszURL);

  public:
    VSICurlStreamingHandle(VSICurlStreamingFSHandler *poFS,
                           const char *pszFilename, const char *pszURL);
    ~VSICurlStreamingHandle() override;

    int Seek(vsi_l_offset nOffset, int nWhence) override;
    vsi_l_offset Tell() override;
    size_t Read(void *pBuffer, size_t nSize, size_t nMemb) override;
    size_t Write(const void *pBuffer, size_t nSize, size_t nMemb) override;
    void ClearErr() override;
    int Error() override;
    int Eof() override;
    int Flush() override;
    int Close() override;

    void DownloadInThread();
    size_t ReceivedBytes(GByte *buffer, size_t count, size_t nmemb);
    size_t ReceivedBytesHeader(GByte *buffer, size_t count, size_t nmemb);

    bool IsKnownFileSize() const
    {
        return bHasComputedFileSize;
    }

    vsi_l_offset GetFileSize();
    bool Exists(const char *pszFilename, CSLConstList papszOptions);

    bool IsDirectory() const
    {
        return bIsDirectory;
    }

    const char *GetURL() const
    {
        return m_pszURL;
    }
};

/************************************************************************/
/*                       VSICurlStreamingHandle()                       */
/************************************************************************/

VSICurlStreamingHandle::VSICurlStreamingHandle(VSICurlStreamingFSHandler *poFS,
                                               const char *pszFilename,
                                               const char *pszURL)
    : m_poFS(poFS), m_aosHTTPOptions(CPLHTTPGetOptionsFromEnv(pszFilename)),
      m_oRetryParameters(m_aosHTTPOptions), m_pszURL(CPLStrdup(pszURL))
{
    FileProp cachedFileProp;
    poFS->GetCachedFileProp(pszURL, cachedFileProp);
    eExists = cachedFileProp.eExists;
    fileSize = cachedFileProp.fileSize;
    bHasComputedFileSize = cachedFileProp.bHasComputedFileSize;
    bIsDirectory = cachedFileProp.bIsDirectory;
    poFS->SetCachedFileProp(pszURL, cachedFileProp);

    hRingBufferMutex = CPLCreateMutex();
    ReleaseMutex();
    hCondProducer = CPLCreateCond();
    hCondConsumer = CPLCreateCond();

    memset(m_szCurlErrBuf, 0, sizeof(m_szCurlErrBuf));
}

/************************************************************************/
/*                       ~VSICurlStreamingHandle()                      */
/************************************************************************/

VSICurlStreamingHandle::~VSICurlStreamingHandle()
{
    StopDownload();

    CPLFree(m_pszURL);

    CPLFree(pCachedData);

    CPLFree(pabyHeaderData);

    CPLDestroyMutex(hRingBufferMutex);
    CPLDestroyCond(hCondProducer);
    CPLDestroyCond(hCondConsumer);
}

/************************************************************************/
/*                            SetURL()                                  */
/************************************************************************/

void VSICurlStreamingHandle::SetURL(const char *pszURLIn)
{
    CPLFree(m_pszURL);
    m_pszURL = CPLStrdup(pszURLIn);
}

/************************************************************************/
/*                         AcquireMutex()                               */
/************************************************************************/

void VSICurlStreamingHandle::AcquireMutex()
{
    CPLAcquireMutex(hRingBufferMutex, 1000.0);
}

/************************************************************************/
/*                          ReleaseMutex()                              */
/************************************************************************/

void VSICurlStreamingHandle::ReleaseMutex()
{
    CPLReleaseMutex(hRingBufferMutex);
}

/************************************************************************/
/*                                Seek()                                */
/************************************************************************/

int VSICurlStreamingHandle::Seek(vsi_l_offset nOffset, int nWhence)
{
    if (curOffset >= BKGND_BUFFER_SIZE)
    {
        if (ENABLE_DEBUG)
            CPLDebug("VSICURL",
                     "Invalidating cache and file size due to Seek() "
                     "beyond caching zone");
        CPLFree(pCachedData);
        pCachedData = nullptr;
        nCachedSize = 0;
        AcquireMutex();
        bHasComputedFileSize = false;
        fileSize = 0;
        ReleaseMutex();
    }

    if (nWhence == SEEK_SET)
    {
        curOffset = nOffset;
    }
    else if (nWhence == SEEK_CUR)
    {
        curOffset = curOffset + nOffset;
    }
    else
    {
        curOffset = GetFileSize() + nOffset;
    }
    bEOF = false;
    return 0;
}

/************************************************************************/
/*                  VSICURLStreamingInitWriteFuncStructStreaming() */
/************************************************************************/

static void
VSICURLStreamingInitWriteFuncStructStreaming(WriteFuncStructStreaming *psStruct)
{
    psStruct->pBuffer = nullptr;
    psStruct->nSize = 0;
    psStruct->bIsHTTP = FALSE;
    psStruct->bIsInHeader = TRUE;
    psStruct->nHTTPCode = 0;
    psStruct->bDownloadHeaderOnly = FALSE;
}

/************************************************************************/
/*                 VSICurlStreamingHandleWriteFuncForHeader()           */
/************************************************************************/

static size_t VSICurlStreamingHandleWriteFuncForHeader(void *buffer,
                                                       size_t count,
                                                       size_t nmemb, void *req)
{
    WriteFuncStructStreaming *psStruct =
        static_cast<WriteFuncStructStreaming *>(req);
    const size_t nSize = count * nmemb;

    char *pNewBuffer = static_cast<char *>(
        VSIRealloc(psStruct->pBuffer, psStruct->nSize + nSize + 1));
    if (pNewBuffer)
    {
        psStruct->pBuffer = pNewBuffer;
        memcpy(psStruct->pBuffer + psStruct->nSize, buffer, nSize);
        psStruct->pBuffer[psStruct->nSize + nSize] = '\0';
        if (psStruct->bIsHTTP && psStruct->bIsInHeader)
        {
            char *pszLine = psStruct->pBuffer + psStruct->nSize;
            if (STARTS_WITH_CI(pszLine, "HTTP/"))
            {
                const char *pszSpace =
                    strchr(const_cast<const char *>(pszLine), ' ');
                if (pszSpace)
                    psStruct->nHTTPCode = atoi(pszSpace + 1);
            }

            if (pszLine[0] == '\r' || pszLine[0] == '\n')
            {
                if (psStruct->bDownloadHeaderOnly)
                {
                    // If moved permanently/temporarily, go on.
                    // Otherwise stop now.
                    if (!(psStruct->nHTTPCode == 301 ||
                          psStruct->nHTTPCode == 302 ||
                          psStruct->nHTTPCode == 303))
                        return 0;
                }
                else
                {
                    psStruct->bIsInHeader = FALSE;
                }
            }
        }
        psStruct->nSize += nSize;
        return nmemb;
    }
    else
    {
        return 0;
    }
}

/************************************************************************/
/*                           GetFileSize()                              */
/************************************************************************/

vsi_l_offset VSICurlStreamingHandle::GetFileSize()
{
    WriteFuncStructStreaming sWriteFuncData;
    WriteFuncStructStreaming sWriteFuncHeaderData;

    AcquireMutex();
    if (bHasComputedFileSize)
    {
        const vsi_l_offset nRet = fileSize;
        ReleaseMutex();
        return nRet;
    }
    ReleaseMutex();

    CURL *hLocalHandle = curl_easy_init();

    struct curl_slist *headers =
        VSICurlSetOptions(hLocalHandle, m_pszURL, m_aosHTTPOptions.List());

    VSICURLStreamingInitWriteFuncStructStreaming(&sWriteFuncHeaderData);

    // HACK for mbtiles driver: Proper fix would be to auto-detect servers that
    // don't accept HEAD http://a.tiles.mapbox.com/v3/ doesn't accept HEAD, so
    // let's start a GET and interrupt is as soon as the header is found.
    CPLString osVerb;
    if (strstr(m_pszURL, ".tiles.mapbox.com/") != nullptr)
    {
        unchecked_curl_easy_setopt(hLocalHandle, CURLOPT_HEADERDATA,
                                   &sWriteFuncHeaderData);
        unchecked_curl_easy_setopt(hLocalHandle, CURLOPT_HEADERFUNCTION,
                                   VSICurlStreamingHandleWriteFuncForHeader);

        sWriteFuncHeaderData.bIsHTTP = STARTS_WITH(m_pszURL, "http");
        sWriteFuncHeaderData.bDownloadHeaderOnly = TRUE;
        osVerb = "GET";
    }
    else
    {
        unchecked_curl_easy_setopt(hLocalHandle, CURLOPT_NOBODY, 1);
        unchecked_curl_easy_setopt(hLocalHandle, CURLOPT_HTTPGET, 0);
        unchecked_curl_easy_setopt(hLocalHandle, CURLOPT_HEADER, 1);
        osVerb = "HEAD";
    }

    headers = VSICurlMergeHeaders(headers, GetCurlHeaders(osVerb, headers));
    unchecked_curl_easy_setopt(hLocalHandle, CURLOPT_HTTPHEADER, headers);

    // We need that otherwise OSGEO4W's libcurl issue a dummy range request
    // when doing a HEAD when recycling connections.
    unchecked_curl_easy_setopt(hLocalHandle, CURLOPT_RANGE, nullptr);

    // Bug with older curl versions (<=7.16.4) and FTP.
    // See http://curl.haxx.se/mail/lib-2007-08/0312.html
    VSICURLStreamingInitWriteFuncStructStreaming(&sWriteFuncData);
    unchecked_curl_easy_setopt(hLocalHandle, CURLOPT_WRITEDATA,
                               &sWriteFuncData);
    unchecked_curl_easy_setopt(hLocalHandle, CURLOPT_WRITEFUNCTION,
                               VSICurlStreamingHandleWriteFuncForHeader);

    char szCurlErrBuf[CURL_ERROR_SIZE + 1] = {};
    unchecked_curl_easy_setopt(hLocalHandle, CURLOPT_ERRORBUFFER, szCurlErrBuf);

    void *old_handler = CPLHTTPIgnoreSigPipe();
    curl_easy_perform(hLocalHandle);
    CPLHTTPRestoreSigPipeHandler(old_handler);
    if (headers != nullptr)
        curl_slist_free_all(headers);

    AcquireMutex();

    eExists = EXIST_UNKNOWN;
    bHasComputedFileSize = true;

    if (STARTS_WITH(m_pszURL, "ftp"))
    {
        if (sWriteFuncData.pBuffer != nullptr &&
            STARTS_WITH_CI(sWriteFuncData.pBuffer, "Content-Length: "))
        {
            const char *pszBuffer =
                sWriteFuncData.pBuffer + strlen("Content-Length: ");
            eExists = EXIST_YES;
            fileSize = CPLScanUIntBig(
                pszBuffer, static_cast<int>(sWriteFuncData.nSize -
                                            strlen("Content-Length: ")));
            if (ENABLE_DEBUG)
                CPLDebug("VSICURL", "GetFileSize(%s)=" CPL_FRMT_GUIB, m_pszURL,
                         fileSize);
        }
    }

    double dfSize = 0;
    if (eExists != EXIST_YES)
    {
        curl_off_t nSizeTmp = 0;
        const CURLcode code = curl_easy_getinfo(
            hLocalHandle, CURLINFO_CONTENT_LENGTH_DOWNLOAD_T, &nSizeTmp);
        CPL_IGNORE_RET_VAL(dfSize);
        dfSize = static_cast<double>(nSizeTmp);
        if (code == 0)
        {
            eExists = EXIST_YES;
            if (dfSize < 0)
                fileSize = 0;
            else
                fileSize = static_cast<GUIntBig>(dfSize);
        }
        else
        {
            eExists = EXIST_NO;
            fileSize = 0;
            CPLError(CE_Failure, CPLE_AppDefined,
                     "VSICurlStreamingHandle::GetFileSize failed");
        }

        long response_code = 0;
        curl_easy_getinfo(hLocalHandle, CURLINFO_HTTP_CODE, &response_code);
        if (response_code != 200)
        {
            eExists = EXIST_NO;
            fileSize = 0;
        }

        // Try to guess if this is a directory. Generally if this is a
        // directory, curl will retry with an URL with slash added.
        char *pszEffectiveURL = nullptr;
        curl_easy_getinfo(hLocalHandle, CURLINFO_EFFECTIVE_URL,
                          &pszEffectiveURL);
        if (pszEffectiveURL != nullptr &&
            strncmp(m_pszURL, pszEffectiveURL, strlen(m_pszURL)) == 0 &&
            pszEffectiveURL[strlen(m_pszURL)] == '/')
        {
            eExists = EXIST_YES;
            fileSize = 0;
            bIsDirectory = true;
        }

        if (ENABLE_DEBUG)
            CPLDebug("VSICURL",
                     "GetFileSize(%s)=" CPL_FRMT_GUIB " response_code=%d",
                     m_pszURL, fileSize, static_cast<int>(response_code));
    }

    CPLFree(sWriteFuncData.pBuffer);
    CPLFree(sWriteFuncHeaderData.pBuffer);

    FileProp cachedFileProp;
    m_poFS->GetCachedFileProp(m_pszURL, cachedFileProp);
    cachedFileProp.bHasComputedFileSize = true;
    cachedFileProp.fileSize = fileSize;
    cachedFileProp.eExists = eExists;
    cachedFileProp.bIsDirectory = bIsDirectory;
    if (cachedFileProp.nMode == 0)
        cachedFileProp.nMode = bIsDirectory ? S_IFDIR : S_IFREG;
    m_poFS->SetCachedFileProp(m_pszURL, cachedFileProp);

    const vsi_l_offset nRet = fileSize;
    ReleaseMutex();

    curl_easy_cleanup(hLocalHandle);

    return nRet;
}

/************************************************************************/
/*                                 Exists()                             */
/************************************************************************/

bool VSICurlStreamingHandle::Exists(const char *pszFilename,
                                    CSLConstList papszOptions)
{
    if (eExists == EXIST_UNKNOWN)
    {
        if (!papszOptions ||
            !CPLTestBool(CSLFetchNameValueDef(
                papszOptions, "IGNORE_FILENAME_RESTRICTIONS", "NO")))
        {
            if (!VSICurlFilesystemHandlerBase::IsAllowedFilename(pszFilename))
            {
                eExists = EXIST_NO;
                fileSize = 0;

                FileProp cachedFileProp;
                m_poFS->GetCachedFileProp(m_pszURL, cachedFileProp);
                cachedFileProp.bHasComputedFileSize = true;
                cachedFileProp.fileSize = fileSize;
                cachedFileProp.eExists = eExists;
                cachedFileProp.bIsDirectory = false;
                cachedFileProp.nMode = S_IFREG;
                m_poFS->SetCachedFileProp(m_pszURL, cachedFileProp);

                return false;
            }
        }

        char chFirstByte = '\0';
        int bExists = (Read(&chFirstByte, 1, 1) == 1);

        FileProp cachedFileProp;
        m_poFS->GetCachedFileProp(m_pszURL, cachedFileProp);
        cachedFileProp.eExists = eExists = bExists ? EXIST_YES : EXIST_NO;
        m_poFS->SetCachedFileProp(m_pszURL, cachedFileProp);

        Seek(0, SEEK_SET);
    }

    return eExists == EXIST_YES;
}

/************************************************************************/
/*                                  Tell()                              */
/************************************************************************/

vsi_l_offset VSICurlStreamingHandle::Tell()
{
    return curOffset;
}

/************************************************************************/
/*                         ReceivedBytes()                              */
/************************************************************************/

size_t VSICurlStreamingHandle::ReceivedBytes(GByte *buffer, size_t count,
                                             size_t nmemb)
{
    size_t nSize = count * nmemb;
    nBodySize += nSize;

    if (ENABLE_DEBUG)
        CPLDebug("VSICURL", "Receiving %d bytes...", static_cast<int>(nSize));

    if (bHasCandidateFileSize && bCanTrustCandidateFileSize &&
        !bHasComputedFileSize)
    {
        FileProp cachedFileProp;
        m_poFS->GetCachedFileProp(m_pszURL, cachedFileProp);
        cachedFileProp.fileSize = fileSize = nCandidateFileSize;
        bHasCandidateFileSize = TRUE;
        cachedFileProp.bHasComputedFileSize = bHasComputedFileSize;
        m_poFS->SetCachedFileProp(m_pszURL, cachedFileProp);
        if (ENABLE_DEBUG)
            CPLDebug("VSICURL", "File size = " CPL_FRMT_GUIB, fileSize);
    }

    AcquireMutex();
    if (eExists == EXIST_UNKNOWN)
    {
        FileProp cachedFileProp;
        m_poFS->GetCachedFileProp(m_pszURL, cachedFileProp);
        cachedFileProp.eExists = eExists = EXIST_YES;
        m_poFS->SetCachedFileProp(m_pszURL, cachedFileProp);
    }
    else if (eExists == EXIST_NO && StopReceivingBytesOnError())
    {
        ReleaseMutex();
        return 0;
    }

    while (true)
    {
        const size_t nFree = oRingBuffer.GetCapacity() - oRingBuffer.GetSize();
        if (nSize <= nFree)
        {
            oRingBuffer.Write(buffer, nSize);

            // Signal to the consumer that we have added bytes to the buffer.
            CPLCondSignal(hCondProducer);

            if (bAskDownloadEnd)
            {
                if (ENABLE_DEBUG)
                    CPLDebug("VSICURL", "Download interruption asked");

                ReleaseMutex();
                return 0;
            }
            break;
        }
        else
        {
            oRingBuffer.Write(buffer, nFree);
            buffer += nFree;
            nSize -= nFree;

            // Signal to the consumer that we have added bytes to the buffer.
            CPLCondSignal(hCondProducer);

            if (ENABLE_DEBUG)
                CPLDebug("VSICURL",
                         "Waiting for reader to consume some bytes...");

            while (oRingBuffer.GetSize() == oRingBuffer.GetCapacity() &&
                   !bAskDownloadEnd)
            {
                CPLCondWait(hCondConsumer, hRingBufferMutex);
            }

            if (bAskDownloadEnd)
            {
                if (ENABLE_DEBUG)
                    CPLDebug("VSICURL", "Download interruption asked");

                ReleaseMutex();
                return 0;
            }
        }
    }

    ReleaseMutex();

    return nmemb;
}

/************************************************************************/
/*                 VSICurlStreamingHandleReceivedBytes()                */
/************************************************************************/

static size_t VSICurlStreamingHandleReceivedBytes(void *buffer, size_t count,
                                                  size_t nmemb, void *req)
{
    return static_cast<VSICurlStreamingHandle *>(req)->ReceivedBytes(
        static_cast<GByte *>(buffer), count, nmemb);
}

/************************************************************************/
/*              VSICurlStreamingHandleReceivedBytesHeader()             */
/************************************************************************/

#define HEADER_SIZE 32768

size_t VSICurlStreamingHandle::ReceivedBytesHeader(GByte *buffer, size_t count,
                                                   size_t nmemb)
{
    const size_t nSize = count * nmemb;
    if (ENABLE_DEBUG)
        CPLDebug("VSICURL", "Receiving %d bytes for header...",
                 static_cast<int>(nSize));

    // Reset buffer if we have followed link after a redirect.
    if (nSize >= 9 && InterpretRedirect() &&
        (nHTTPCode == 301 || nHTTPCode == 302 || nHTTPCode == 303) &&
        STARTS_WITH_CI(reinterpret_cast<char *>(buffer), "HTTP/"))
    {
        nHeaderSize = 0;
        nHTTPCode = 0;
    }

    if (nHeaderSize < HEADER_SIZE)
    {
        const size_t nSz = std::min(nSize, HEADER_SIZE - nHeaderSize);
        memcpy(pabyHeaderData + nHeaderSize, buffer, nSz);
        pabyHeaderData[nHeaderSize + nSz] = '\0';
        nHeaderSize += nSz;

#if DEBUG_VERBOSE
        CPLDebug("VSICURL", "Header : %s", pabyHeaderData);
#endif

        AcquireMutex();

        if (nHTTPCode == 0 &&
            strchr(reinterpret_cast<char *>(pabyHeaderData), '\n') != nullptr &&
            STARTS_WITH_CI(reinterpret_cast<char *>(pabyHeaderData), "HTTP/"))
        {
            const char *pszSpace =
                strchr(const_cast<const char *>(
                           reinterpret_cast<char *>(pabyHeaderData)),
                       ' ');
            if (pszSpace)
                nHTTPCode = atoi(pszSpace + 1);
            if (ENABLE_DEBUG)
                CPLDebug("VSICURL", "HTTP code = %d", nHTTPCode);

            // If moved permanently/temporarily, go on.
            if (eExists == EXIST_UNKNOWN &&
                !(InterpretRedirect() &&
                  (nHTTPCode == 301 || nHTTPCode == 302 || nHTTPCode == 303)))
            {
                eExists = nHTTPCode == 200 ? EXIST_YES : EXIST_NO;
                FileProp cachedFileProp;
                m_poFS->GetCachedFileProp(m_pszURL, cachedFileProp);
                cachedFileProp.eExists = eExists;
                m_poFS->SetCachedFileProp(m_pszURL, cachedFileProp);
            }
        }

        if (!(InterpretRedirect() &&
              (nHTTPCode == 301 || nHTTPCode == 302 || nHTTPCode == 303)) &&
            !bHasComputedFileSize)
        {
            // Caution: When gzip compression is enabled, the content-length is
            // the compressed size, which we are not interested in, so we must
            // not take it into account.

            const char *pszContentLength = strstr(
                reinterpret_cast<char *>(pabyHeaderData), "Content-Length: ");
            const char *pszEndOfLine =
                pszContentLength ? strchr(pszContentLength, '\n') : nullptr;
            if (bCanTrustCandidateFileSize && pszEndOfLine != nullptr)
            {
                const char *pszVal =
                    pszContentLength + strlen("Content-Length: ");
                bHasCandidateFileSize = true;
                nCandidateFileSize = CPLScanUIntBig(
                    pszVal, static_cast<int>(pszEndOfLine - pszVal));
                if (ENABLE_DEBUG)
                    CPLDebug("VSICURL",
                             "Has found candidate file size = " CPL_FRMT_GUIB,
                             nCandidateFileSize);
            }

            const char *pszContentEncoding = strstr(
                reinterpret_cast<char *>(pabyHeaderData), "Content-Encoding: ");
            pszEndOfLine =
                pszContentEncoding ? strchr(pszContentEncoding, '\n') : nullptr;
            if (bHasCandidateFileSize && pszEndOfLine != nullptr)
            {
                const char *pszVal =
                    pszContentEncoding + strlen("Content-Encoding: ");
                if (STARTS_WITH(pszVal, "gzip"))
                {
                    if (ENABLE_DEBUG)
                        CPLDebug("VSICURL", "GZip compression enabled --> "
                                            "cannot trust candidate file size");
                    bCanTrustCandidateFileSize = false;
                }
            }
        }

        ReleaseMutex();
    }

    return nmemb;
}

/************************************************************************/
/*                 VSICurlStreamingHandleReceivedBytesHeader()          */
/************************************************************************/

static size_t VSICurlStreamingHandleReceivedBytesHeader(void *buffer,
                                                        size_t count,
                                                        size_t nmemb, void *req)
{
    return static_cast<VSICurlStreamingHandle *>(req)->ReceivedBytesHeader(
        static_cast<GByte *>(buffer), count, nmemb);
}

/************************************************************************/
/*                       DownloadInThread()                             */
/************************************************************************/

void VSICurlStreamingHandle::DownloadInThread()
{
    CURL *hCurlHandle = curl_easy_init();

    struct curl_slist *headers =
        VSICurlSetOptions(hCurlHandle, m_pszURL, m_aosHTTPOptions.List());
    headers = VSICurlMergeHeaders(headers, GetCurlHeaders("GET", headers));
    unchecked_curl_easy_setopt(hCurlHandle, CURLOPT_HTTPHEADER, headers);

    static bool bHasCheckVersion = false;
    static bool bSupportGZip = false;
    if (!bHasCheckVersion)
    {
        bSupportGZip = strstr(curl_version(), "zlib/") != nullptr;
        bHasCheckVersion = true;
    }
    if (bSupportGZip && CPLTestBool(CPLGetConfigOption("CPL_CURL_GZIP", "YES")))
    {
        unchecked_curl_easy_setopt(hCurlHandle, CURLOPT_ENCODING, "gzip");
    }

    if (pabyHeaderData == nullptr)
        pabyHeaderData = static_cast<GByte *>(CPLMalloc(HEADER_SIZE + 1));
    nHeaderSize = 0;
    nBodySize = 0;
    nHTTPCode = 0;

    unchecked_curl_easy_setopt(hCurlHandle, CURLOPT_HEADERDATA, this);
    unchecked_curl_easy_setopt(hCurlHandle, CURLOPT_HEADERFUNCTION,
                               VSICurlStreamingHandleReceivedBytesHeader);

    unchecked_curl_easy_setopt(hCurlHandle, CURLOPT_WRITEDATA, this);
    unchecked_curl_easy_setopt(hCurlHandle, CURLOPT_WRITEFUNCTION,
                               VSICurlStreamingHandleReceivedBytes);

    m_szCurlErrBuf[0] = '\0';
    unchecked_curl_easy_setopt(hCurlHandle, CURLOPT_ERRORBUFFER,
                               m_szCurlErrBuf);

    void *old_handler = CPLHTTPIgnoreSigPipe();
    CURLcode eRet = curl_easy_perform(hCurlHandle);
    CPLHTTPRestoreSigPipeHandler(old_handler);
    if (headers != nullptr)
        curl_slist_free_all(headers);

    unchecked_curl_easy_setopt(hCurlHandle, CURLOPT_WRITEDATA, nullptr);
    unchecked_curl_easy_setopt(hCurlHandle, CURLOPT_WRITEFUNCTION, nullptr);
    unchecked_curl_easy_setopt(hCurlHandle, CURLOPT_HEADERDATA, nullptr);
    unchecked_curl_easy_setopt(hCurlHandle, CURLOPT_HEADERFUNCTION, nullptr);

    AcquireMutex();
    m_bErrorOccurredInThread = eRet != CURLE_OK;
    if (m_bErrorOccurredInThread)
    {
        // For autotest purposes only !
        const char *pszSimulatedCurlError = CPLGetConfigOption(
            "CPL_VSIL_CURL_STREMAING_SIMULATED_CURL_ERROR", nullptr);
        if (pszSimulatedCurlError)
            snprintf(m_szCurlErrBuf, sizeof(m_szCurlErrBuf), "%s",
                     pszSimulatedCurlError);
    }

    if (!bAskDownloadEnd && eRet == CURLE_OK && !bHasComputedFileSize)
    {
        FileProp cachedFileProp;
        m_poFS->GetCachedFileProp(m_pszURL, cachedFileProp);
        fileSize = nBodySize;
        cachedFileProp.fileSize = fileSize;
        bHasComputedFileSize = true;
        cachedFileProp.bHasComputedFileSize = bHasComputedFileSize;
        m_poFS->SetCachedFileProp(m_pszURL, cachedFileProp);
        if (ENABLE_DEBUG)
            CPLDebug("VSICURL", "File size = " CPL_FRMT_GUIB, fileSize);
    }

    bDownloadInProgress = FALSE;
    bDownloadStopped = TRUE;

    // Signal to the consumer that the download has ended.
    CPLCondSignal(hCondProducer);
    ReleaseMutex();

    curl_easy_cleanup(hCurlHandle);
}

static void VSICurlDownloadInThread(void *pArg)
{
    static_cast<VSICurlStreamingHandle *>(pArg)->DownloadInThread();
}

/************************************************************************/
/*                            StartDownload()                            */
/************************************************************************/

void VSICurlStreamingHandle::StartDownload()
{
    if (bDownloadInProgress || bDownloadStopped)
        return;

    CPLDebug("VSICURL", "Start download for %s", m_pszURL);

    oRingBuffer.Reset();
    bDownloadInProgress = TRUE;
    nRingBufferFileOffset = 0;
    m_bErrorOccurredInThread = false;
    hThread = CPLCreateJoinableThread(VSICurlDownloadInThread, this);
}

/************************************************************************/
/*                            StopDownload()                            */
/************************************************************************/

void VSICurlStreamingHandle::StopDownload()
{
    if (hThread)
    {
        CPLDebug("VSICURL", "Stop download for %s", m_pszURL);

        AcquireMutex();
        // Signal to the producer that we ask for download interruption.
        bAskDownloadEnd = TRUE;
        CPLCondSignal(hCondConsumer);

        // Wait for the producer to have finished.
        while (bDownloadInProgress)
            CPLCondWait(hCondProducer, hRingBufferMutex);

        bAskDownloadEnd = FALSE;

        ReleaseMutex();

        CPLJoinThread(hThread);
        hThread = nullptr;
    }

    oRingBuffer.Reset();
    bDownloadStopped = FALSE;
    m_bErrorOccurredInThread = false;
    nRingBufferFileOffset = 0;
    bEOF = false;
}

/************************************************************************/
/*                        PutRingBufferInCache()                        */
/************************************************************************/

void VSICurlStreamingHandle::PutRingBufferInCache()
{
    if (nRingBufferFileOffset >= BKGND_BUFFER_SIZE)
        return;

    AcquireMutex();

    // Cache any remaining bytes available in the ring buffer.
    size_t nBufSize = oRingBuffer.GetSize();
    if (nBufSize > 0)
    {
        if (nRingBufferFileOffset + nBufSize > BKGND_BUFFER_SIZE)
            nBufSize =
                static_cast<size_t>(BKGND_BUFFER_SIZE - nRingBufferFileOffset);
        GByte *pabyTmp = static_cast<GByte *>(CPLMalloc(nBufSize));
        oRingBuffer.Read(pabyTmp, nBufSize);

        // Signal to the producer that we have ingested some bytes.
        CPLCondSignal(hCondConsumer);

        AddRegion(nRingBufferFileOffset, nBufSize, pabyTmp);
        nRingBufferFileOffset += nBufSize;
        CPLFree(pabyTmp);
    }

    ReleaseMutex();
}

/************************************************************************/
/*                                Read()                                */
/************************************************************************/

size_t VSICurlStreamingHandle::Read(void *const pBuffer, size_t const nSize,
                                    size_t const nMemb)
{
    const size_t nBufferRequestSize = nSize * nMemb;
    const vsi_l_offset curOffsetOri = curOffset;
    const vsi_l_offset nRingBufferFileOffsetOri = nRingBufferFileOffset;
    if (nBufferRequestSize == 0)
        return 0;

    CPLHTTPRetryContext oRetryContext(m_oRetryParameters);

retry:
    GByte *pabyBuffer = static_cast<GByte *>(pBuffer);
    size_t nRemaining = nBufferRequestSize;

    AcquireMutex();
    // fileSize might be set wrongly to 0, such as
    // /vsicurl_streaming/https://query.data.world/s/jgsghstpphjhicstradhy5kpjwrnfy
    const bool bHasComputedFileSizeLocal = bHasComputedFileSize && fileSize > 0;
    const vsi_l_offset fileSizeLocal = fileSize;
    ReleaseMutex();

    if (bHasComputedFileSizeLocal && curOffset >= fileSizeLocal)
    {
        CPLDebug("VSICURL", "Read attempt beyond end of file");
        bEOF = true;
    }
    if (bEOF)
        return 0;

    if (curOffset < nRingBufferFileOffset)
        PutRingBufferInCache();

    if (ENABLE_DEBUG)
        CPLDebug("VSICURL", "Read [" CPL_FRMT_GUIB ", " CPL_FRMT_GUIB "[ in %s",
                 curOffset, curOffset + nBufferRequestSize, m_pszURL);

    // Can we use the cache?
    if (pCachedData != nullptr && curOffset < nCachedSize)
    {
        const size_t nSz =
            std::min(nRemaining, static_cast<size_t>(nCachedSize - curOffset));
        if (ENABLE_DEBUG)
            CPLDebug("VSICURL", "Using cache for [%d, %d[ in %s",
                     static_cast<int>(curOffset),
                     static_cast<int>(curOffset + nSz), m_pszURL);
        memcpy(pabyBuffer, pCachedData + curOffset, nSz);
        pabyBuffer += nSz;
        curOffset += nSz;
        nRemaining -= nSz;
    }

    // Is the request partially covered by the cache and going beyond file size?
    if (pCachedData != nullptr && bHasComputedFileSizeLocal &&
        curOffset <= nCachedSize && curOffset + nRemaining > fileSizeLocal &&
        fileSize == nCachedSize)
    {
        size_t nSz = static_cast<size_t>(nCachedSize - curOffset);
        if (ENABLE_DEBUG && nSz != 0)
            CPLDebug("VSICURL", "Using cache for [%d, %d[ in %s",
                     static_cast<int>(curOffset),
                     static_cast<int>(curOffset + nSz), m_pszURL);
        memcpy(pabyBuffer, pCachedData + curOffset, nSz);
        pabyBuffer += nSz;
        curOffset += nSz;
        nRemaining -= nSz;
        bEOF = true;
    }

    bool bErrorOccurred = false;

    // Has a Seek() being done since the last Read()?
    if (!bEOF && nRemaining > 0 && curOffset != nRingBufferFileOffset)
    {
        // Backward seek: Need to restart the download from the beginning.
        if (curOffset < nRingBufferFileOffset)
            StopDownload();

        StartDownload();

        const vsi_l_offset SKIP_BUFFER_SIZE = 32768;
        GByte *pabyTmp = static_cast<GByte *>(CPLMalloc(SKIP_BUFFER_SIZE));

        CPLAssert(curOffset >= nRingBufferFileOffset);
        vsi_l_offset nBytesToSkip = curOffset - nRingBufferFileOffset;
        while (nBytesToSkip > 0)
        {
            vsi_l_offset nBytesToRead = nBytesToSkip;

            AcquireMutex();
            if (nBytesToRead > oRingBuffer.GetSize())
                nBytesToRead = oRingBuffer.GetSize();
            if (nBytesToRead > SKIP_BUFFER_SIZE)
                nBytesToRead = SKIP_BUFFER_SIZE;
            oRingBuffer.Read(pabyTmp, static_cast<size_t>(nBytesToRead));

            // Signal to the producer that we have ingested some bytes.
            CPLCondSignal(hCondConsumer);
            ReleaseMutex();

            if (nBytesToRead)
                AddRegion(nRingBufferFileOffset,
                          static_cast<size_t>(nBytesToRead), pabyTmp);

            nBytesToSkip -= nBytesToRead;
            nRingBufferFileOffset += nBytesToRead;

            if (nBytesToRead == 0 && nBytesToSkip != 0)
            {
                if (ENABLE_DEBUG)
                    CPLDebug("VSICURL",
                             "Waiting for writer to produce some bytes...");

                AcquireMutex();
                while (oRingBuffer.GetSize() == 0 && bDownloadInProgress)
                    CPLCondWait(hCondProducer, hRingBufferMutex);
                const int bBufferEmpty = (oRingBuffer.GetSize() == 0);
                bErrorOccurred = m_bErrorOccurredInThread;
                ReleaseMutex();

                if (bBufferEmpty && !bDownloadInProgress)
                    break;
            }
        }

        CPLFree(pabyTmp);

        if (nBytesToSkip != 0 && !bErrorOccurred)
        {
            bEOF = true;
            return 0;
        }
    }

    if (!bEOF && nRemaining > 0 && !bErrorOccurred)
    {
        StartDownload();
        CPLAssert(curOffset == nRingBufferFileOffset);
    }

    // Fill the destination buffer from the ring buffer.
    while (!bEOF && nRemaining > 0 && !bErrorOccurred)
    {
        AcquireMutex();
        size_t nToRead = oRingBuffer.GetSize();
        if (nToRead > nRemaining)
            nToRead = nRemaining;
        oRingBuffer.Read(pabyBuffer, nToRead);

        // Signal to the producer that we have ingested some bytes.
        CPLCondSignal(hCondConsumer);
        ReleaseMutex();

        if (nToRead)
            AddRegion(curOffset, nToRead, pabyBuffer);

        nRemaining -= nToRead;
        pabyBuffer += nToRead;
        curOffset += nToRead;
        nRingBufferFileOffset += nToRead;

        if (nToRead == 0 && nRemaining != 0)
        {
            if (ENABLE_DEBUG)
                CPLDebug("VSICURL",
                         "Waiting for writer to produce some bytes...");

            AcquireMutex();
            while (oRingBuffer.GetSize() == 0 && bDownloadInProgress)
                CPLCondWait(hCondProducer, hRingBufferMutex);
            const bool bBufferEmpty = oRingBuffer.GetSize() == 0;
            bErrorOccurred = m_bErrorOccurredInThread;
            ReleaseMutex();

            if (bBufferEmpty && !bDownloadInProgress)
                break;
        }
    }

    if (ENABLE_DEBUG)
        CPLDebug("VSICURL", "Read(%d) = %d",
                 static_cast<int>(nBufferRequestSize),
                 static_cast<int>(nBufferRequestSize - nRemaining));
    size_t nRet = (nBufferRequestSize - nRemaining) / nSize;
    if (nRet < nMemb)
        bEOF = true;

    // Give a chance to specialized filesystem to deal with errors to redirect
    // elsewhere.
    if (curOffsetOri == 0 && nRingBufferFileOffsetOri == 0 &&
        !StopReceivingBytesOnError() && eExists == EXIST_NO &&
        nRemaining < nBufferRequestSize)
    {
        const size_t nErrorBufferMaxSize = 4096;
        GByte *pabyErrorBuffer =
            static_cast<GByte *>(CPLMalloc(nErrorBufferMaxSize + 1));
        size_t nRead = nBufferRequestSize - nRemaining;
        size_t nErrorBufferSize = std::min(nErrorBufferMaxSize, nRead);
        memcpy(pabyErrorBuffer, pBuffer, nErrorBufferSize);
        if (nRead < nErrorBufferMaxSize)
            nErrorBufferSize +=
                Read(pabyErrorBuffer + nRead, 1, nErrorBufferMaxSize - nRead);
        pabyErrorBuffer[nErrorBufferSize] = 0;
        StopDownload();
        if (CanRestartOnError(reinterpret_cast<char *>(pabyErrorBuffer),
                              reinterpret_cast<char *>(pabyHeaderData), true))
        {
            curOffset = 0;

            AcquireMutex();
            eExists = EXIST_UNKNOWN;
            bHasComputedFileSize = false;
            fileSize = 0;
            ReleaseMutex();
            nCachedSize = 0;

            FileProp cachedFileProp;
            m_poFS->GetCachedFileProp(m_pszURL, cachedFileProp);
            cachedFileProp.bHasComputedFileSize = false;
            cachedFileProp.fileSize = 0;
            cachedFileProp.eExists = EXIST_UNKNOWN;
            m_poFS->SetCachedFileProp(m_pszURL, cachedFileProp);

            goto retry;
        }
        else
        {
            CPLDebug("VSICURL", "Error buffer: %s",
                     reinterpret_cast<char *>(pabyErrorBuffer));
            nRet = 0;
        }

        CPLFree(pabyErrorBuffer);
    }

    if (bErrorOccurred)
    {
        // Look if we should attempt a retry
        AcquireMutex();
        const bool bRetry = oRetryContext.CanRetry(static_cast<int>(nHTTPCode),
                                                   nullptr, m_szCurlErrBuf);
        ReleaseMutex();
        if (bRetry)
        {
            StopDownload();

            CPLError(CE_Warning, CPLE_AppDefined,
                     "HTTP error code: %d - %s. "
                     "Retrying again in %.1f secs",
                     static_cast<int>(nHTTPCode), m_pszURL,
                     oRetryContext.GetCurrentDelay());
            CPLSleep(oRetryContext.GetCurrentDelay());
            curOffset = curOffsetOri;
            goto retry;
        }
    }

    if (bErrorOccurred)
        m_bError = true;

    return nRet;
}

/************************************************************************/
/*                          AddRegion()                                 */
/************************************************************************/

void VSICurlStreamingHandle::AddRegion(vsi_l_offset nFileOffsetStart,
                                       size_t nSize, GByte *pData)
{
    if (nFileOffsetStart >= BKGND_BUFFER_SIZE)
        return;

    if (pCachedData == nullptr)
        pCachedData = static_cast<GByte *>(CPLMalloc(BKGND_BUFFER_SIZE));

    if (nFileOffsetStart <= nCachedSize &&
        nFileOffsetStart + nSize > nCachedSize)
    {
        const size_t nSz = std::min(
            nSize, static_cast<size_t>(BKGND_BUFFER_SIZE - nFileOffsetStart));
        if (ENABLE_DEBUG)
            CPLDebug("VSICURL", "Writing [%d, %d[ in cache for %s",
                     static_cast<int>(nFileOffsetStart),
                     static_cast<int>(nFileOffsetStart + nSz), m_pszURL);
        memcpy(pCachedData + nFileOffsetStart, pData, nSz);
        nCachedSize = static_cast<size_t>(nFileOffsetStart + nSz);
    }
}

/************************************************************************/
/*                               Write()                                */
/************************************************************************/

size_t VSICurlStreamingHandle::Write(const void * /* pBuffer */,
                                     size_t /* nSize */, size_t /* nMemb */)
{
    return 0;
}

/************************************************************************/
/*                                 Eof()                                */
/************************************************************************/

int VSICurlStreamingHandle::Eof()
{
    return bEOF;
}

/************************************************************************/
/*                               Error()                                */
/************************************************************************/

int VSICurlStreamingHandle::Error()

{
    return m_bError;
}

/************************************************************************/
/*                             ClearErr()                               */
/************************************************************************/

void VSICurlStreamingHandle::ClearErr()
{
    bEOF = false;
    m_bError = false;
}

/************************************************************************/
/*                                 Flush()                              */
/************************************************************************/

int VSICurlStreamingHandle::Flush()
{
    return 0;
}

/************************************************************************/
/*                                  Close()                             */
/************************************************************************/

int VSICurlStreamingHandle::Close()
{
    return 0;
}

/************************************************************************/
/*                      VSICurlStreamingFSHandler()                     */
/************************************************************************/

VSICurlStreamingFSHandler::VSICurlStreamingFSHandler()
    : oCacheFileProp{100 * 1024}
{
    hMutex = CPLCreateMutex();
    CPLReleaseMutex(hMutex);
}

/************************************************************************/
/*                      ~VSICurlStreamingFSHandler()                    */
/************************************************************************/

VSICurlStreamingFSHandler::~VSICurlStreamingFSHandler()
{
    VSICurlStreamingFSHandler::ClearCache();

    CPLDestroyMutex(hMutex);
    hMutex = nullptr;
}

/************************************************************************/
/*                            ClearCache()                              */
/************************************************************************/

void VSICurlStreamingFSHandler::ClearCache()
{
    CPLMutexHolder oHolder(&hMutex);

    {
        const auto lambda = [](const lru11::KeyValuePair<std::string, bool> &kv)
        { VSICURLInvalidateCachedFileProp(kv.key.c_str()); };
        oCacheFileProp.cwalk(lambda);
        oCacheFileProp.clear();
    }
}

/************************************************************************/
/*                         AcquireMutex()                               */
/************************************************************************/

void VSICurlStreamingFSHandler::AcquireMutex()
{
    CPLAcquireMutex(hMutex, 1000.0);
}

/************************************************************************/
/*                         ReleaseMutex()                               */
/************************************************************************/

void VSICurlStreamingFSHandler::ReleaseMutex()
{
    CPLReleaseMutex(hMutex);
}

/************************************************************************/
/*                          CreateFileHandle()                          */
/************************************************************************/

VSICurlStreamingHandle *
VSICurlStreamingFSHandler::CreateFileHandle(const char *pszFilename,
                                            const char *pszURL)
{
    return new VSICurlStreamingHandle(this, pszFilename, pszURL);
}

/************************************************************************/
/*                                Open()                                */
/************************************************************************/

VSIVirtualHandle *VSICurlStreamingFSHandler::Open(const char *pszFilename,
                                                  const char *pszAccess,
                                                  bool /* bSetError */,
                                                  CSLConstList papszOptions)
{
    if (!STARTS_WITH_CI(pszFilename, GetFSPrefix()))
        return nullptr;

    if (strchr(pszAccess, 'w') != nullptr || strchr(pszAccess, '+') != nullptr)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Only read-only mode is supported for %s",
                 GetFSPrefix().c_str());
        return nullptr;
    }

    VSICurlStreamingHandle *poHandle =
        CreateFileHandle(pszFilename, pszFilename + GetFSPrefix().size());
    // If we didn't get a filelist, check that the file really exists.
    if (poHandle == nullptr || !poHandle->Exists(pszFilename, papszOptions))
    {
        delete poHandle;
        return nullptr;
    }

    if (CPLTestBool(CPLGetConfigOption("VSI_CACHE", "FALSE")))
        return VSICreateCachedFile(poHandle);

    return poHandle;
}

/************************************************************************/
/*                         GetCachedFileProp()                          */
/************************************************************************/

bool VSICurlStreamingFSHandler::GetCachedFileProp(const char *pszURL,
                                                  FileProp &oFileProp)
{
    CPLMutexHolder oHolder(&hMutex);
    bool inCache;
    if (oCacheFileProp.tryGet(std::string(pszURL), inCache))
    {
        if (VSICURLGetCachedFileProp(pszURL, oFileProp))
        {
            return true;
        }
        oCacheFileProp.remove(std::string(pszURL));
    }
    return false;
}

/************************************************************************/
/*                         SetCachedFileProp()                          */
/************************************************************************/

void VSICurlStreamingFSHandler::SetCachedFileProp(const char *pszURL,
                                                  FileProp &oFileProp)
{
    CPLMutexHolder oHolder(&hMutex);
    oCacheFileProp.insert(std::string(pszURL), true);
    VSICURLSetCachedFileProp(pszURL, oFileProp);
}

/************************************************************************/
/*                                Stat()                                */
/************************************************************************/

int VSICurlStreamingFSHandler::Stat(const char *pszFilename,
                                    VSIStatBufL *pStatBuf, int nFlags)
{
    if (!STARTS_WITH_CI(pszFilename, GetFSPrefix()))
        return -1;

    if ((nFlags & VSI_STAT_CACHE_ONLY) != 0)
    {
        const std::string osVSICURLFilename =
            std::string("/vsicurl/") + (pszFilename + GetFSPrefix().size());
        return VSIStatExL(osVSICURLFilename.c_str(), pStatBuf, nFlags);
    }

    memset(pStatBuf, 0, sizeof(VSIStatBufL));

    VSICurlStreamingHandle *poHandle =
        CreateFileHandle(pszFilename, pszFilename + GetFSPrefix().size());
    if (poHandle == nullptr)
    {
        return -1;
    }
    if (poHandle->IsKnownFileSize() ||
        ((nFlags & VSI_STAT_SIZE_FLAG) && !poHandle->IsDirectory() &&
         CPLTestBool(CPLGetConfigOption("CPL_VSIL_CURL_SLOW_GET_SIZE", "YES"))))
    {
        pStatBuf->st_size = poHandle->GetFileSize();
    }

    int nRet = (poHandle->Exists(pszFilename, nullptr)) ? 0 : -1;
    pStatBuf->st_mode = poHandle->IsDirectory() ? S_IFDIR : S_IFREG;

    delete poHandle;
    return nRet;
}

/************************************************************************/
/*                          GetActualURL()                              */
/************************************************************************/

const char *VSICurlStreamingFSHandler::GetActualURL(const char *pszFilename)
{
    if (!STARTS_WITH_CI(pszFilename, GetFSPrefix()))
        return pszFilename;
    auto poHandle = std::unique_ptr<VSICurlStreamingHandle>(
        CreateFileHandle(pszFilename, pszFilename + GetFSPrefix().size()));
    if (poHandle == nullptr)
        return pszFilename;
    return CPLSPrintf("%s", poHandle->GetURL());
}

/************************************************************************/
/*                       GetNonStreamingFilename()                      */
/************************************************************************/

std::string VSICurlStreamingFSHandler::GetNonStreamingFilename(
    const std::string &osFilename) const
{
    if (STARTS_WITH(osFilename.c_str(), GetFSPrefix().c_str()))
        return GetNonStreamingPrefix() +
               osFilename.substr(GetFSPrefix().size());
    return osFilename;
}

/************************************************************************/
/*                      IVSIS3LikeStreamingFSHandler                    */
/************************************************************************/

class IVSIS3LikeStreamingFSHandler : public VSICurlStreamingFSHandler
{
    CPL_DISALLOW_COPY_ASSIGN(IVSIS3LikeStreamingFSHandler)

  public:
    IVSIS3LikeStreamingFSHandler() = default;

    char **ReadDirEx(const char *pszDirname, int nMaxFiles) override
    {
        if (STARTS_WITH(pszDirname, GetFSPrefix()))
        {
            return VSIReadDirEx(
                (GetNonStreamingPrefix() + (pszDirname + GetFSPrefix().size()))
                    .c_str(),
                nMaxFiles);
        }
        return nullptr;
    }

    const char *GetOptions() override
    {
        return VSIGetFileSystemOptions(GetNonStreamingPrefix().c_str());
    }
};

/************************************************************************/
/*                       VSIS3StreamingFSHandler                        */
/************************************************************************/

class VSIS3StreamingFSHandler final : public IVSIS3LikeStreamingFSHandler
{
    CPL_DISALLOW_COPY_ASSIGN(VSIS3StreamingFSHandler)

  protected:
    CPLString GetFSPrefix() const override
    {
        return "/vsis3_streaming/";
    }

    std::string GetNonStreamingPrefix() const override
    {
        return "/vsis3/";
    }

    VSICurlStreamingHandle *CreateFileHandle(const char *pszFilename,
                                             const char *pszURL) override;

  public:
    VSIS3StreamingFSHandler() = default;
    ~VSIS3StreamingFSHandler() override = default;

    void ClearCache() override
    {
        IVSIS3LikeStreamingFSHandler::ClearCache();
        VSIS3UpdateParams::ClearCache();
    }
};

/************************************************************************/
/*                          VSIS3LikeStreamingHandle                    */
/************************************************************************/

class VSIS3LikeStreamingHandle final : public VSICurlStreamingHandle
{
    CPL_DISALLOW_COPY_ASSIGN(VSIS3LikeStreamingHandle)

    IVSIS3LikeHandleHelper *m_poS3HandleHelper = nullptr;

  protected:
    struct curl_slist *
    GetCurlHeaders(const CPLString &osVerb,
                   const struct curl_slist *psExistingHeaders) override;

    bool StopReceivingBytesOnError() override
    {
        return false;
    }

    bool CanRestartOnError(const char *pszErrorMsg, const char *pszHeaders,
                           bool bSetError) override;

    bool InterpretRedirect() override
    {
        return false;
    }

  public:
    VSIS3LikeStreamingHandle(IVSIS3LikeStreamingFSHandler *poFS,
                             const char *pszFilename,
                             IVSIS3LikeHandleHelper *poS3HandleHelper);
    ~VSIS3LikeStreamingHandle() override;
};

/************************************************************************/
/*                          CreateFileHandle()                          */
/************************************************************************/

VSICurlStreamingHandle *
VSIS3StreamingFSHandler::CreateFileHandle(const char *pszFilename,
                                          const char *pszURL)
{
    VSIS3HandleHelper *poS3HandleHelper =
        VSIS3HandleHelper::BuildFromURI(pszURL, GetFSPrefix().c_str(), false);
    if (poS3HandleHelper)
    {
        return new VSIS3LikeStreamingHandle(this, pszFilename,
                                            poS3HandleHelper);
    }
    return nullptr;
}

/************************************************************************/
/*                     VSIS3LikeStreamingHandle()                       */
/************************************************************************/

VSIS3LikeStreamingHandle::VSIS3LikeStreamingHandle(
    IVSIS3LikeStreamingFSHandler *poFS, const char *pszFilename,
    IVSIS3LikeHandleHelper *poS3HandleHelper)
    : VSICurlStreamingHandle(poFS, pszFilename,
                             poS3HandleHelper->GetURL().c_str()),
      m_poS3HandleHelper(poS3HandleHelper)
{
}

/************************************************************************/
/*                     ~VSIS3LikeStreamingHandle()                      */
/************************************************************************/

VSIS3LikeStreamingHandle::~VSIS3LikeStreamingHandle()
{
    delete m_poS3HandleHelper;
}

/************************************************************************/
/*                           GetCurlHeaders()                           */
/************************************************************************/

struct curl_slist *VSIS3LikeStreamingHandle::GetCurlHeaders(
    const CPLString &osVerb, const struct curl_slist *psExistingHeaders)
{
    return m_poS3HandleHelper->GetCurlHeaders(osVerb, psExistingHeaders);
}

/************************************************************************/
/*                          CanRestartOnError()                         */
/************************************************************************/

bool VSIS3LikeStreamingHandle::CanRestartOnError(const char *pszErrorMsg,
                                                 const char *pszHeaders,
                                                 bool bSetError)
{
    if (m_poS3HandleHelper->CanRestartOnError(pszErrorMsg, pszHeaders,
                                              bSetError))
    {
        SetURL(m_poS3HandleHelper->GetURL().c_str());
        return true;
    }
    return false;
}

/************************************************************************/
/*                       VSIGSStreamingFSHandler                        */
/************************************************************************/

class VSIGSStreamingFSHandler final : public IVSIS3LikeStreamingFSHandler
{
  protected:
    CPLString GetFSPrefix() const override
    {
        return "/vsigs_streaming/";
    }

    std::string GetNonStreamingPrefix() const override
    {
        return "/vsigs/";
    }

    VSICurlStreamingHandle *CreateFileHandle(const char *pszFilename,
                                             const char *pszURL) override;

  public:
    VSIGSStreamingFSHandler()
    {
    }

    ~VSIGSStreamingFSHandler() override
    {
    }
};

/************************************************************************/
/*                          CreateFileHandle()                          */
/************************************************************************/

VSICurlStreamingHandle *
VSIGSStreamingFSHandler::CreateFileHandle(const char *pszFilename,
                                          const char *pszURL)
{
    VSIGSHandleHelper *poGCHandleHelper =
        VSIGSHandleHelper::BuildFromURI(pszURL, GetFSPrefix().c_str());
    if (poGCHandleHelper)
    {
        return new VSIS3LikeStreamingHandle(this, pszFilename,
                                            poGCHandleHelper);
    }
    return nullptr;
}

/************************************************************************/
/*                      VSIAzureStreamingFSHandler                      */
/************************************************************************/

class VSIAzureStreamingFSHandler final : public IVSIS3LikeStreamingFSHandler
{
  protected:
    CPLString GetFSPrefix() const override
    {
        return "/vsiaz_streaming/";
    }

    std::string GetNonStreamingPrefix() const override
    {
        return "/vsiaz/";
    }

    VSICurlStreamingHandle *CreateFileHandle(const char *pszFilename,
                                             const char *pszURL) override;

  public:
    VSIAzureStreamingFSHandler()
    {
    }

    ~VSIAzureStreamingFSHandler() override
    {
    }
};

/************************************************************************/
/*                          CreateFileHandle()                          */
/************************************************************************/

VSICurlStreamingHandle *
VSIAzureStreamingFSHandler::CreateFileHandle(const char *pszFilename,
                                             const char *pszURL)
{
    VSIAzureBlobHandleHelper *poHandleHelper =
        VSIAzureBlobHandleHelper::BuildFromURI(pszURL, GetFSPrefix().c_str());
    if (poHandleHelper)
    {
        return new VSIS3LikeStreamingHandle(this, pszFilename, poHandleHelper);
    }
    return nullptr;
}

/************************************************************************/
/*                       VSIOSSStreamingFSHandler                        */
/************************************************************************/

class VSIOSSStreamingFSHandler final : public IVSIS3LikeStreamingFSHandler
{
    CPL_DISALLOW_COPY_ASSIGN(VSIOSSStreamingFSHandler)

  protected:
    CPLString GetFSPrefix() const override
    {
        return "/vsioss_streaming/";
    }

    std::string GetNonStreamingPrefix() const override
    {
        return "/vsioss/";
    }

    VSICurlStreamingHandle *CreateFileHandle(const char *pszFilename,
                                             const char *pszURL) override;

  public:
    VSIOSSStreamingFSHandler() = default;
    ~VSIOSSStreamingFSHandler() override = default;

    void ClearCache() override
    {
        IVSIS3LikeStreamingFSHandler::ClearCache();
        VSIOSSUpdateParams::ClearCache();
    }
};

/************************************************************************/
/*                          CreateFileHandle()                          */
/************************************************************************/

VSICurlStreamingHandle *
VSIOSSStreamingFSHandler::CreateFileHandle(const char *pszFilename,
                                           const char *pszURL)
{
    VSIOSSHandleHelper *poOSSHandleHelper =
        VSIOSSHandleHelper::BuildFromURI(pszURL, GetFSPrefix().c_str(), false);
    if (poOSSHandleHelper)
    {
        return new VSIS3LikeStreamingHandle(this, pszFilename,
                                            poOSSHandleHelper);
    }
    return nullptr;
}

/************************************************************************/
/*                      VSISwiftStreamingFSHandler                      */
/************************************************************************/

class VSISwiftStreamingFSHandler final : public IVSIS3LikeStreamingFSHandler
{
  protected:
    CPLString GetFSPrefix() const override
    {
        return "/vsiswift_streaming/";
    }

    std::string GetNonStreamingPrefix() const override
    {
        return "/vsiswift/";
    }

    VSICurlStreamingHandle *CreateFileHandle(const char *pszFilename,
                                             const char *pszURL) override;

  public:
    VSISwiftStreamingFSHandler()
    {
    }

    ~VSISwiftStreamingFSHandler() override
    {
    }
};

/************************************************************************/
/*                          CreateFileHandle()                          */
/************************************************************************/

VSICurlStreamingHandle *
VSISwiftStreamingFSHandler::CreateFileHandle(const char *pszFilename,
                                             const char *pszURL)
{
    VSISwiftHandleHelper *poHandleHelper =
        VSISwiftHandleHelper::BuildFromURI(pszURL, GetFSPrefix().c_str());
    if (poHandleHelper)
    {
        return new VSIS3LikeStreamingHandle(this, pszFilename, poHandleHelper);
    }
    return nullptr;
}

//! @endcond

} /* namespace cpl */

/************************************************************************/
/*                 VSIInstallCurlStreamingFileHandler()                 */
/************************************************************************/

/*!
 \brief Install /vsicurl_streaming/ HTTP/FTP file system handler (requires
 libcurl).

  \verbatim embed:rst
 See :ref:`/vsicurl_streaming/ documentation <vsicurl_streaming>`
 \endverbatim

 @since GDAL 1.10
 */
void VSIInstallCurlStreamingFileHandler(void)
{
    VSIFileManager::InstallHandler("/vsicurl_streaming/",
                                   new cpl::VSICurlStreamingFSHandler);
}

/************************************************************************/
/*                   VSIInstallS3StreamingFileHandler()                 */
/************************************************************************/

/*!
 \brief Install /vsis3_streaming/ Amazon S3 file system handler (requires
 libcurl).

  \verbatim embed:rst
 See :ref:`/vsis3_streaming/ documentation <vsis3_streaming>`
 \endverbatim

 @since GDAL 2.1
 */
void VSIInstallS3StreamingFileHandler(void)
{
    VSIFileManager::InstallHandler("/vsis3_streaming/",
                                   new cpl::VSIS3StreamingFSHandler);
}

/************************************************************************/
/*                      VSIInstallGSStreamingFileHandler()              */
/************************************************************************/

/*!
 \brief Install /vsigs_streaming/ Google Cloud Storage file system handler
 (requires libcurl)

  \verbatim embed:rst
 See :ref:`/vsigs_streaming/ documentation <vsigs_streaming>`
 \endverbatim

 @since GDAL 2.2
 */

void VSIInstallGSStreamingFileHandler(void)
{
    VSIFileManager::InstallHandler("/vsigs_streaming/",
                                   new cpl::VSIGSStreamingFSHandler);
}

/************************************************************************/
/*                   VSIInstallAzureStreamingFileHandler()              */
/************************************************************************/

/*!
 \brief Install /vsiaz_streaming/ Microsoft Azure Blob file system handler
 (requires libcurl)

  \verbatim embed:rst
 See :ref:`/vsiaz_streaming/ documentation <vsiaz_streaming>`
 \endverbatim

 @since GDAL 2.3
 */

void VSIInstallAzureStreamingFileHandler(void)
{
    VSIFileManager::InstallHandler("/vsiaz_streaming/",
                                   new cpl::VSIAzureStreamingFSHandler);
}

/************************************************************************/
/*                    VSIInstallOSSStreamingFileHandler()               */
/************************************************************************/

/*!
 \brief Install /vsiaz_streaming/ Alibaba Cloud Object Storage Service (OSS)
 (requires libcurl)

  \verbatim embed:rst
 See :ref:`/vsioss_streaming/ documentation <vsioss_streaming>`
 \endverbatim

 @since GDAL 2.3
 */

void VSIInstallOSSStreamingFileHandler(void)
{
    VSIFileManager::InstallHandler("/vsioss_streaming/",
                                   new cpl::VSIOSSStreamingFSHandler);
}

/************************************************************************/
/*                  VSIInstallSwiftStreamingFileHandler()               */
/************************************************************************/

/*!
 \brief Install /vsiswift_streaming/ OpenStack Swif Object Storage (Swift) file
 system handler (requires libcurl)

  \verbatim embed:rst
 See :ref:`/vsiswift_streaming/ documentation <vsiswift_streaming>`
 \endverbatim

 @since GDAL 2.3
 */

void VSIInstallSwiftStreamingFileHandler(void)
{
    VSIFileManager::InstallHandler("/vsiswift_streaming/",
                                   new cpl::VSISwiftStreamingFSHandler);
}

//! @cond Doxygen_Suppress

/************************************************************************/
/*                      VSICurlStreamingClearCache()                    */
/************************************************************************/

void VSICurlStreamingClearCache(void)
{
    // FIXME ? Currently we have different filesystem instances for
    // vsicurl/, /vsis3/, /vsigs/ . So each one has its own cache of regions.
    // File properties cache are now shared
    char **papszPrefix = VSIFileManager::GetPrefixes();
    for (size_t i = 0; papszPrefix && papszPrefix[i]; ++i)
    {
        auto poFSHandler = dynamic_cast<cpl::VSICurlStreamingFSHandler *>(
            VSIFileManager::GetHandler(papszPrefix[i]));

        if (poFSHandler)
            poFSHandler->ClearCache();
    }
    CSLDestroy(papszPrefix);
}

//! @endcond

#undef ENABLE_DEBUG

#endif  // !defined(HAVE_CURL) || defined(CPL_MULTIPROC_STUB)