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

 *

 * Project:  CPL - Common Portability Library

 * Purpose:  Implement CPLGetExecPath().

 * Author:   Frank Warmerdam, warmerdam@pobox.com

 *

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

 * Copyright (c) 2005, Frank Warmerdam

 *

 * SPDX-License-Identifier: MIT

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

#include "cpl_port.h"

#include "cpl_conv.h"

#if HAVE_UNISTD_H

#include <unistd.h>

#endif

#include "cpl_multiproc.h"

#include "cpl_string.h"

#if defined(_WIN32)

#include <windows.h>

#elif defined(__MACH__) && defined(__APPLE__)

#include <mach-o/dyld.h>

#elif defined(__FreeBSD__) || defined(__NetBSD__)

#include <sys/sysctl.h>

#include <sys/types.h>

#endif

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

/*                           CPLGetExecPath()                           */

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

/**

 * Fetch path of executable.

 *

 * The path to the executable currently running is returned.  This path

 * includes the name of the executable. Currently this only works on

 * Windows, Linux, MacOS, FreeBSD and netBSD platforms.  The returned path is UTF-8

 * encoded, and will be nul-terminated if success is reported.

 *

 * @param pszPathBuf the buffer into which the path is placed.

 * @param nMaxLength the buffer size (including the nul-terminating character).

 * MAX_PATH+1 is suggested.

 *

 * @return FALSE on failure or TRUE on success.

 */

int CPLGetExecPath(char *pszPathBuf, int nMaxLength)

{

    if (nMaxLength == 0)

        return FALSE;

    pszPathBuf[0] = '\0';

#if defined(_WIN32)

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

    {

        wchar_t *pwszPathBuf =

            static_cast<wchar_t *>(CPLCalloc(nMaxLength + 1, sizeof(wchar_t)));

        if (GetModuleFileNameW(nullptr, pwszPathBuf, nMaxLength) == 0)

        {

            CPLFree(pwszPathBuf);

            return FALSE;

        }

        else

        {

            char *pszDecoded =

                CPLRecodeFromWChar(pwszPathBuf, CPL_ENC_UCS2, CPL_ENC_UTF8);

            const size_t nStrlenDecoded = strlen(pszDecoded);

            strncpy(pszPathBuf, pszDecoded, nMaxLength);

            int bOK = TRUE;

            if (nStrlenDecoded >= static_cast<size_t>(nMaxLength) - 1)

            {

                pszPathBuf[nMaxLength - 1] = '\0';

                // There is no easy way to detect if the string has been

                // truncated other than testing the existence of the file.

                VSIStatBufL sStat;

                bOK = (VSIStatL(pszPathBuf, &sStat) == 0);

            }

            CPLFree(pszDecoded);

            CPLFree(pwszPathBuf);

            return bOK;

        }

    }

    else

    {

        if (GetModuleFileNameA(nullptr, pszPathBuf, nMaxLength) == 0)

            return FALSE;

        else

        {

            const size_t nStrlenDecoded = strlen(pszPathBuf);

            int bOK = TRUE;

            if (nStrlenDecoded >= static_cast<size_t>(nMaxLength) - 1)

            {

                pszPathBuf[nMaxLength - 1] = '\0';

                // There is no easy way to detect if the string has been

                // truncated other than testing the existence of the file.

                VSIStatBufL sStat;

                bOK = (VSIStatL(pszPathBuf, &sStat) == 0);

            }

            return bOK;

        }

    }

#elif defined(__linux)

    long nPID = getpid();

    CPLString osExeLink;

    osExeLink.Printf("/proc/%ld/exe", nPID);

    ssize_t nResultLen = readlink(osExeLink, pszPathBuf, nMaxLength);

    if (nResultLen == nMaxLength)

        pszPathBuf[nMaxLength - 1] = '\0';

    else if (nResultLen >= 0)

        pszPathBuf[nResultLen] = '\0';

    return nResultLen > 0 && nResultLen < nMaxLength;

#elif defined(__MACH__) && defined(__APPLE__)

    uint32_t size = static_cast<uint32_t>(nMaxLength);

    if (_NSGetExecutablePath(pszPathBuf, &size) == 0)

    {

        return TRUE;

    }

    return FALSE;

#elif defined(__FreeBSD__)

    int mib[4];

    mib[0] = CTL_KERN;

    mib[1] = KERN_PROC;

    mib[2] = KERN_PROC_PATHNAME;

    mib[3] = -1;

    size_t size = static_cast<size_t>(nMaxLength);

    if (sysctl(mib, 4, pszPathBuf, &size, nullptr, 0) == 0)

    {

        return TRUE;

    }

    return FALSE;

#elif defined(__NetBSD__)

    int mib[4];

    mib[0] = CTL_KERN;

    mib[1] = KERN_PROC_ARGS;

    mib[2] = -1;

    mib[3] = KERN_PROC_PATHNAME;

    size_t size = static_cast<size_t>(nMaxLength);

    if (sysctl(mib, 4, pszPathBuf, &size, nullptr, 0) == 0)

    {

        return TRUE;

    }

    return FALSE;

#else

    return FALSE;

#endif

}