/*
    Copyright 2005-2011 Intel Corporation.  All Rights Reserved.

    This file is part of Threading Building Blocks.

    Threading Building Blocks is free software; you can redistribute it
    and/or modify it under the terms of the GNU General Public License
    version 2 as published by the Free Software Foundation.

    Threading Building Blocks is distributed in the hope that it will be
    useful, but WITHOUT ANY WARRANTY; without even the implied warranty
    of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with Threading Building Blocks; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    As a special exception, you may use this file as part of a free software
    library without restriction.  Specifically, if other files instantiate
    templates or use macros or inline functions from this file, or you compile
    this file and link it with other files to produce an executable, this
    file does not by itself cause the resulting executable to be covered by
    the GNU General Public License.  This exception does not however
    invalidate any other reasons why the executable file might be covered by
    the GNU General Public License.
*/

#ifndef __TBB_runtime_loader_H
#define __TBB_runtime_loader_H

#if ! TBB_PREVIEW_RUNTIME_LOADER
    #error Set TBB_PREVIEW_RUNTIME_LOADER to include runtime_loader.h
#endif

#include "tbb/tbb_stddef.h"
#include <climits>

#if _MSC_VER
    #if ! __TBB_NO_IMPLICIT_LINKAGE
        #ifdef _DEBUG
            #pragma comment( linker, "/nodefaultlib:tbb_debug.lib" )
            #pragma comment( linker, "/defaultlib:tbbproxy_debug.lib" )
        #else
            #pragma comment( linker, "/nodefaultlib:tbb.lib" )
            #pragma comment( linker, "/defaultlib:tbbproxy.lib" )
        #endif
    #endif
#endif

namespace tbb {

namespace interface6 {

//! Load TBB at runtime.
/*!

\b Usage:

In source code:

\code
#include "tbb/runtime_loader.h"

char const * path[] = { "/usr/local/lib64", NULL };
tbb::runtime_loader loader( path );

// Now use TBB.
\endcode

Link with \c libtbbproxy.a (or \c tbbproxy.lib) instead of \c libtbb.so (\c libtbb.dylib,
\c tbb.lib).

TBB library will be loaded at runtime from \c /usr/local/lib64/ directory.

\b Attention:

All \c runtime_loader objects (in the same module) share some global state.
The most noticeable piece of global state is loaded TBB library.
There are some implications:

    -   Only one TBB library can be loaded.

    -   If one object has already loaded TBB library, another object will not load TBB.
        If the loaded TBB library is suitable for the second object, both will use TBB
        cooperatively, otherwise the second object will report an error.

    -   \c runtime_loader objects will not work (correctly) in parallel due to absence of
        syncronization.

*/

class runtime_loader : tbb::internal::no_copy {

    public:

        //! Error mode constants.
        enum error_mode {
            em_status,     //!< Save status of operation and continue.
            em_throw,      //!< Throw an exception of tbb::runtime_loader::error_code type.
            em_abort       //!< Print message to \c stderr and call \c abort().
        }; // error_mode

        //! Error codes.
        enum error_code {
            ec_ok,         //!< No errors.
            ec_bad_call,   //!< Invalid function call (e. g. load() called when TBB is already loaded).
            ec_bad_arg,    //!< Invalid argument passed.
            ec_bad_lib,    //!< Invalid library found (e. g. \c TBB_runtime_version symbol not found).
            ec_bad_ver,    //!< TBB found but version is not suitable.
            ec_no_lib      //!< No suitable TBB library found.
        }; // error_code

        //! Initialize object but do not load TBB.
        runtime_loader( error_mode mode = em_abort );

        //! Initialize object and load TBB.
        /*!
            See load() for details.

            If error mode is \c em_status, call status() to check whether TBB was loaded or not.
        */
        runtime_loader(
            char const * path[],                           //!< List of directories to search TBB in.
            int          min_ver = TBB_INTERFACE_VERSION,  //!< Minimal suitable version of TBB.
            int          max_ver = INT_MAX,                //!< Maximal suitable version of TBB.
            error_mode   mode    = em_abort                //!< Error mode for this object.
        );

        //! Destroy object.
        ~runtime_loader();

        //! Load TBB.
        /*!
            The method searches the directories specified in \c path[] array for the TBB library.
            When the library is found, it is loaded and its version is checked. If the version is
            not suitable, the library is unloaded, and the search continues.

            Empty directory name (\c "") has a special meaning. It causes searching TBB in
            system default directories.

            \b Note:

            For security reasons, avoid using relative directory names. For example, never load
            TBB from current (\c "."), parent (\c "..") or any other relative directory (like
            \c "lib" ). Use only absolute directory names (e. g. "/usr/local/lib").

            For the same security reasons, avoid using system default directories (\c "") on
            Windows. (See http://www.microsoft.com/technet/security/advisory/2269637.mspx for
            details.)

            Neglecting these rules may cause your program to execute 3-rd party malicious code.

            \b Errors:
                -   \c ec_bad_call - TBB already loaded by this object.
                -   \c ec_bad_arg - \p min_ver and/or \p max_ver negative or zero,
                    or \p min_ver > \p max_ver.
                -   \c ec_bad_ver - TBB of unsuitable version already loaded by another object.
                -   \c ec_no_lib - No suitable library found.
        */
        error_code
        load(
            char const * path[],                           //!< List of directories to search TBB in.
            int          min_ver = TBB_INTERFACE_VERSION,  //!< Minimal suitable version of TBB.
            int          max_ver = INT_MAX                 //!< Maximal suitable version of TBB.

        );


        //! Report status.
        /*!
            If error mode is \c em_status, the function returns status of the last operation.
        */
        error_code status();

    private:

        error_mode const my_mode;
        error_code       my_status;
        bool             my_loaded;

}; // class runtime_loader

} // namespace interface6

using interface6::runtime_loader;

} // namespace tbb

#endif /* __TBB_runtime_loader_H */

