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

 *

 * Project:  GDAL Core

 * Purpose:  Implementation of GDALOpenInfo class.

 * Author:   Frank Warmerdam, warmerdam@pobox.com

 *

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

 * Copyright (c) 2002, Frank Warmerdam

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

 *

 * SPDX-License-Identifier: MIT

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

#include "gdal_priv.h"  // Must be included first for mingw VSIStatBufL.

#include "cpl_port.h"

#include <cstdlib>

#include <cstring>

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif

#include <algorithm>

#include <map>

#include <mutex>

#include <vector>

#include "cpl_config.h"

#include "cpl_conv.h"

#include "cpl_error.h"

#include "cpl_string.h"

#include "cpl_vsi.h"

#include "gdal.h"

// Keep in sync prototype of those 2 functions between gdalopeninfo.cpp,

// ogrsqlitedatasource.cpp and ogrgeopackagedatasource.cpp

void GDALOpenInfoDeclareFileNotToOpen(const char *pszFilename,

                                      const GByte *pabyHeader,

                                      int nHeaderBytes);

void GDALOpenInfoUnDeclareFileNotToOpen(const char *pszFilename);

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

/* This whole section helps for SQLite/GPKG, especially with write-ahead

 * log enabled. The issue is that sqlite3 relies on POSIX advisory locks to

 * properly work and decide when to create/delete the wal related files.

 * One issue with POSIX advisory locks is that if within the same process

 * you do

 * f1 = open('somefile')

 * set locks on f1

 * f2 = open('somefile')

 * close(f2)

 * The close(f2) will cancel the locks set on f1. The work on f1 is done by

 * libsqlite3 whereas the work on f2 is done by GDALOpenInfo.

 * So as soon as sqlite3 has opened a file we should make sure not to re-open

 * it (actually close it) ourselves.

 */

namespace

{

struct FileNotToOpen

{

    CPLString osFilename{};

    int nRefCount{};

    GByte *pabyHeader{nullptr};

    int nHeaderBytes{0};

};

}  // namespace

static std::mutex sFNTOMutex;

static std::map<CPLString, FileNotToOpen> *pMapFNTO = nullptr;

void GDALOpenInfoDeclareFileNotToOpen(const char *pszFilename,

                                      const GByte *pabyHeader, int nHeaderBytes)

{

    std::lock_guard<std::mutex> oLock(sFNTOMutex);

    if (pMapFNTO == nullptr)

        pMapFNTO = new std::map<CPLString, FileNotToOpen>();

    auto oIter = pMapFNTO->find(pszFilename);

    if (oIter != pMapFNTO->end())

    {

        oIter->second.nRefCount++;

    }

    else

    {

        FileNotToOpen fnto;

        fnto.osFilename = pszFilename;

        fnto.nRefCount = 1;

        fnto.pabyHeader = static_cast<GByte *>(CPLMalloc(nHeaderBytes + 1));

        memcpy(fnto.pabyHeader, pabyHeader, nHeaderBytes);

        fnto.pabyHeader[nHeaderBytes] = 0;

        fnto.nHeaderBytes = nHeaderBytes;

        (*pMapFNTO)[pszFilename] = std::move(fnto);

    }

}

void GDALOpenInfoUnDeclareFileNotToOpen(const char *pszFilename)

{

    std::lock_guard<std::mutex> oLock(sFNTOMutex);

    CPLAssert(pMapFNTO);

    auto oIter = pMapFNTO->find(pszFilename);

    CPLAssert(oIter != pMapFNTO->end());

    oIter->second.nRefCount--;

    if (oIter->second.nRefCount == 0)

    {

        CPLFree(oIter->second.pabyHeader);

        pMapFNTO->erase(oIter);

    }

    if (pMapFNTO->empty())

    {

        delete pMapFNTO;

        pMapFNTO = nullptr;

    }

}

static GByte *GDALOpenInfoGetFileNotToOpen(const char *pszFilename,

                                           int *pnHeaderBytes)

{

    std::lock_guard<std::mutex> oLock(sFNTOMutex);

    *pnHeaderBytes = 0;

    if (pMapFNTO == nullptr)

    {

        return nullptr;

    }

    auto oIter = pMapFNTO->find(pszFilename);

    if (oIter == pMapFNTO->end())

    {

        return nullptr;

    }

    *pnHeaderBytes = oIter->second.nHeaderBytes;

    GByte *pabyHeader = static_cast<GByte *>(CPLMalloc(*pnHeaderBytes + 1));

    memcpy(pabyHeader, oIter->second.pabyHeader, *pnHeaderBytes);

    pabyHeader[*pnHeaderBytes] = 0;

    return pabyHeader;

}

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

/* ==================================================================== */

/*                             GDALOpenInfo                             */

/* ==================================================================== */

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

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

/*                            GDALOpenInfo()                            */

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

/** Constructor/

 * @param pszFilenameIn filename

 * @param nOpenFlagsIn open flags

 * @param papszSiblingsIn list of sibling files, or NULL.

 */

GDALOpenInfo::GDALOpenInfo(const char *pszFilenameIn, int nOpenFlagsIn,

                           const char *const *papszSiblingsIn)

    : pszFilename(CPLStrdup(pszFilenameIn)),

      osExtension(CPLGetExtensionSafe(pszFilenameIn)),

      eAccess(nOpenFlagsIn & GDAL_OF_UPDATE ? GA_Update : GA_ReadOnly),

      nOpenFlags(nOpenFlagsIn)

{

    if (STARTS_WITH(pszFilename, "MVT:/vsi"))

        return;

/* -------------------------------------------------------------------- */

/*      Ensure that C: is treated as C:\ so we can stat it on           */

/*      Windows.  Similar to what is done in CPLStat().                 */

/* -------------------------------------------------------------------- */

#ifdef _WIN32

    if (strlen(pszFilenameIn) == 2 && pszFilenameIn[1] == ':')

    {

        char szAltPath[10];

        strcpy(szAltPath, pszFilenameIn);

        strcat(szAltPath, "\\");

        CPLFree(pszFilename);

        pszFilename = CPLStrdup(szAltPath);

    }

#endif  // WIN32

    /* -------------------------------------------------------------------- */

    /*      Collect information about the file.                             */

    /* -------------------------------------------------------------------- */

#ifdef HAVE_READLINK

    bool bHasRetried = false;

retry:  // TODO(schwehr): Stop using goto.

#endif  // HAVE_READLINK

#if !(defined(_WIN32) || defined(__linux__) || defined(__ANDROID__) ||         \

      (defined(__MACH__) && defined(__APPLE__)))

    /* On BSDs, fread() on a directory returns non zero, so we have to */

    /* do a stat() before to check the nature of pszFilename. */

    bool bPotentialDirectory = (eAccess == GA_ReadOnly);

#else

    bool bPotentialDirectory = false;

#endif

    /* Check if the filename might be a directory of a special virtual file

     * system */

    if (STARTS_WITH(pszFilename, "/vsizip/") ||

        STARTS_WITH(pszFilename, "/vsitar/") ||

        STARTS_WITH(pszFilename, "/vsi7z/") ||

        STARTS_WITH(pszFilename, "/vsirar/"))

    {

        const char *pszExt = osExtension.c_str();

        if (EQUAL(pszExt, "zip") || EQUAL(pszExt, "tar") ||

            EQUAL(pszExt, "gz") || EQUAL(pszExt, "7z") ||

            EQUAL(pszExt, "rar") ||

            pszFilename[strlen(pszFilename) - 1] == '}'

#ifdef DEBUG

            // For AFL, so that .cur_input is detected as the archive filename.

            || EQUAL(CPLGetFilename(pszFilename), ".cur_input")

#endif  // DEBUG

        )

        {

            bPotentialDirectory = true;

        }

    }

    else if (STARTS_WITH(pszFilename, "/vsicurl/"))

    {

        bPotentialDirectory = true;

    }

    if (bPotentialDirectory)

    {

        int nStatFlags = VSI_STAT_EXISTS_FLAG | VSI_STAT_NATURE_FLAG;

        if (nOpenFlagsIn & GDAL_OF_VERBOSE_ERROR)

            nStatFlags |= VSI_STAT_SET_ERROR_FLAG;

        // For those special files, opening them with VSIFOpenL() might result

        // in content, even if they should be considered as directories, so

        // use stat.

        VSIStatBufL sStat;

        if (VSIStatExL(pszFilename, &sStat, nStatFlags) == 0)

        {

            bStatOK = TRUE;

            if (VSI_ISDIR(sStat.st_mode))

                bIsDirectory = TRUE;

        }

    }

    pabyHeader = GDALOpenInfoGetFileNotToOpen(pszFilename, &nHeaderBytes);

    if (!bIsDirectory && pabyHeader == nullptr)

    {

        fpL = VSIFOpenExL(pszFilename, (eAccess == GA_Update) ? "r+b" : "rb",

                          (nOpenFlagsIn & GDAL_OF_VERBOSE_ERROR) > 0);

    }

    if (pabyHeader)

    {

        bStatOK = TRUE;

        nHeaderBytesTried = nHeaderBytes;

    }

    else if (fpL != nullptr)

    {

        bStatOK = TRUE;

        int nBufSize =

            atoi(CPLGetConfigOption("GDAL_INGESTED_BYTES_AT_OPEN", "1024"));

        if (nBufSize < 1024)

            nBufSize = 1024;

        else if (nBufSize > 10 * 1024 * 1024)

            nBufSize = 10 * 1024 * 1024;

        pabyHeader = static_cast<GByte *>(CPLCalloc(nBufSize + 1, 1));

        nHeaderBytesTried = nBufSize;

        nHeaderBytes =

            static_cast<int>(VSIFReadL(pabyHeader, 1, nHeaderBytesTried, fpL));

        VSIRewindL(fpL);

        /* If we cannot read anything, check if it is not a directory instead */

        VSIStatBufL sStat;

        if (nHeaderBytes == 0 &&

            VSIStatExL(pszFilename, &sStat,

                       VSI_STAT_EXISTS_FLAG | VSI_STAT_NATURE_FLAG) == 0 &&

            VSI_ISDIR(sStat.st_mode))

        {

            CPL_IGNORE_RET_VAL(VSIFCloseL(fpL));

            fpL = nullptr;

            CPLFree(pabyHeader);

            pabyHeader = nullptr;

            bIsDirectory = TRUE;

        }

    }

    else if (!bStatOK)

    {

        VSIStatBufL sStat;

        if (!bPotentialDirectory &&

            VSIStatExL(pszFilename, &sStat,

                       VSI_STAT_EXISTS_FLAG | VSI_STAT_NATURE_FLAG) == 0)

        {

            bStatOK = TRUE;

            if (VSI_ISDIR(sStat.st_mode))

                bIsDirectory = TRUE;

        }

#ifdef HAVE_READLINK

        else if (!bHasRetried && !STARTS_WITH(pszFilename, "/vsi"))

        {

            // If someone creates a file with "ln -sf

            // /vsicurl/http://download.osgeo.org/gdal/data/gtiff/utm.tif

            // my_remote_utm.tif" we will be able to open it by passing

            // my_remote_utm.tif.  This helps a lot for GDAL based readers that

            // only provide file explorers to open datasets.

            const int nBufSize = 2048;

            std::vector<char> oFilename(nBufSize);

            char *szPointerFilename = &oFilename[0];

            int nBytes = static_cast<int>(

                readlink(pszFilename, szPointerFilename, nBufSize));

            if (nBytes != -1)

            {

                szPointerFilename[std::min(nBytes, nBufSize - 1)] = 0;

                CPLFree(pszFilename);

                pszFilename = CPLStrdup(szPointerFilename);

                osExtension = CPLGetExtensionSafe(pszFilename);

                papszSiblingsIn = nullptr;

                bHasRetried = true;

                goto retry;

            }

        }

#endif  // HAVE_READLINK

    }

    /* -------------------------------------------------------------------- */

    /*      Capture sibling list either from passed in values, or by        */

    /*      scanning for them only if requested through GetSiblingFiles().  */

    /* -------------------------------------------------------------------- */

    if (papszSiblingsIn != nullptr)

    {

        papszSiblingFiles = CSLDuplicate(papszSiblingsIn);

        bHasGotSiblingFiles = true;

    }

    else if (bStatOK && !bIsDirectory)

    {

        papszSiblingFiles = VSISiblingFiles(pszFilename);

        if (papszSiblingFiles != nullptr)

        {

            bHasGotSiblingFiles = true;

        }

        else

        {

            const char *pszOptionVal = VSIGetPathSpecificOption(

                pszFilename, "GDAL_DISABLE_READDIR_ON_OPEN", "NO");

            if (EQUAL(pszOptionVal, "EMPTY_DIR"))

            {

                papszSiblingFiles =

                    CSLAddString(nullptr, CPLGetFilename(pszFilename));

                bHasGotSiblingFiles = true;

            }

            else if (CPLTestBool(pszOptionVal))

            {

                /* skip reading the directory */

                papszSiblingFiles = nullptr;

                bHasGotSiblingFiles = true;

            }

            else

            {

                /* will be lazy loaded */

                papszSiblingFiles = nullptr;

                bHasGotSiblingFiles = false;

            }

        }

    }

    else

    {

        papszSiblingFiles = nullptr;

        bHasGotSiblingFiles = true;

    }

}

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

/*                           ~GDALOpenInfo()                            */

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

GDALOpenInfo::~GDALOpenInfo()

{

    VSIFree(pabyHeader);

    CPLFree(pszFilename);

    if (fpL != nullptr)

        CPL_IGNORE_RET_VAL(VSIFCloseL(fpL));

    CSLDestroy(papszSiblingFiles);

}

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

/*                         GetSiblingFiles()                            */

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

/** Return sibling files.

 *

 * If the list of sibling files has not already been established, it will be,

 * unless the GDAL_DISABLE_READDIR_ON_OPEN configuration option has been set to

 * YES or EMPTY_DIR when this instance was constructed.

 *

 * @return sibling files. Ownership belongs to "this".

 */

char **GDALOpenInfo::GetSiblingFiles()

{

    if (bHasGotSiblingFiles)

        return papszSiblingFiles;

    bHasGotSiblingFiles = true;

    papszSiblingFiles = VSISiblingFiles(pszFilename);

    if (papszSiblingFiles != nullptr)

    {

        return papszSiblingFiles;

    }

    const CPLString osDir = CPLGetDirnameSafe(pszFilename);

    const int nMaxFiles = atoi(VSIGetPathSpecificOption(

        pszFilename, "GDAL_READDIR_LIMIT_ON_OPEN", "1000"));

    papszSiblingFiles = VSIReadDirEx(osDir, nMaxFiles);

    if (nMaxFiles > 0 && CSLCount(papszSiblingFiles) > nMaxFiles)

    {

        CPLDebug("GDAL", "GDAL_READDIR_LIMIT_ON_OPEN reached on %s",

                 osDir.c_str());

        CSLDestroy(papszSiblingFiles);

        papszSiblingFiles = nullptr;

    }

    return papszSiblingFiles;

}

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

/*                         StealSiblingFiles()                          */

/*                                                                      */

/*      Same as GetSiblingFiles() except that the list is stealed       */

/*      (ie ownership transferred to the caller) and the associated     */

/*      member variable is set to NULL.                                 */

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

/** Return sibling files and steal reference

 * @return sibling files. Ownership below to the caller (must be freed with

 * CSLDestroy)

 */

char **GDALOpenInfo::StealSiblingFiles()

{

    char **papszRet = GetSiblingFiles();

    papszSiblingFiles = nullptr;

    return papszRet;

}

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

/*                        AreSiblingFilesLoaded()                       */

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

/** Return whether sibling files have been loaded.

 * @return true or false.

 */

bool GDALOpenInfo::AreSiblingFilesLoaded() const

{

    return bHasGotSiblingFiles;

}

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

/*                           TryToIngest()                              */

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

/** Ingest bytes from the file.

 * @param nBytes number of bytes to ingest.

 * @return TRUE if successful

 */

int GDALOpenInfo::TryToIngest(int nBytes)

{

    if (fpL == nullptr)

        return FALSE;

    if (nHeaderBytes < nHeaderBytesTried)

        return TRUE;

    pabyHeader = static_cast<GByte *>(CPLRealloc(pabyHeader, nBytes + 1));

    memset(pabyHeader, 0, nBytes + 1);

    VSIRewindL(fpL);

    nHeaderBytesTried = nBytes;

    nHeaderBytes = static_cast<int>(VSIFReadL(pabyHeader, 1, nBytes, fpL));

    VSIRewindL(fpL);

    return TRUE;

}

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

/*                       IsSingleAllowedDriver()                        */

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

/** Returns true if the driver name is the single in the list of allowed

 * drivers.

 *

 * @param pszDriverName Driver name to test.

 * @return true if the driver name is the single in the list of allowed

 * drivers.

 * @since GDAL 3.10

 */

bool GDALOpenInfo::IsSingleAllowedDriver(const char *pszDriverName) const

{

    return papszAllowedDrivers && papszAllowedDrivers[0] &&

           !papszAllowedDrivers[1] &&

           EQUAL(papszAllowedDrivers[0], pszDriverName);

}