/* /////////////////////////////////////////////////////////////////////////////
 * File:        loader.d (originally from synsoft.win32.loader)
 *
 * Purpose:     Win32 exception classes
 *
 * Created      18th October 2003
 * Updated:     24th April 2004
 *
 * Author:      Matthew Wilson
 *
 * License:     (Licensed under the Synesis Software Standard Source License)
 *
 *              Copyright (C) 2002-2004, Synesis Software Pty Ltd.
 *
 *              All rights reserved.
 *
 *              www:        http://www.synesis.com.au/software
 *                          http://www.synsoft.org/
 *
 *              email:      submissions@synsoft.org  for submissions
 *                          admin@synsoft.org        for other enquiries
 *
 *              Redistribution and use in source and binary forms, with or
 *              without modification, are permitted provided that the following
 *              conditions are met:
 *
 *              (i) Redistributions of source code must retain the above
 *              copyright notice and contact information, this list of
 *              conditions and the following disclaimer.
 *
 *              (ii) Any derived versions of this software (howsoever modified)
 *              remain the sole property of Synesis Software.
 *
 *              (iii) Any derived versions of this software (howsoever modified)
 *              remain subject to all these conditions.
 *
 *              (iv) Neither the name of Synesis Software nor the names of any
 *              subdivisions, employees or agents of Synesis Software, nor the
 *              names of any other contributors to this software may be used to
 *              endorse or promote products derived from this software without
 *              specific prior written permission.
 *
 *              This source code is provided by Synesis Software "as is" and any
 *              warranties, whether expressed or implied, including, but not
 *              limited to, the implied warranties of merchantability and
 *              fitness for a particular purpose are disclaimed. In no event
 *              shall the Synesis Software be liable for any direct, indirect,
 *              incidental, special, exemplary, or consequential damages
 *              (including, but not limited to, procurement of substitute goods
 *              or services; loss of use, data, or profits; or business
 *              interruption) however caused and on any theory of liability,
 *              whether in contract, strict liability, or tort (including
 *              negligence or otherwise) arising in any way out of the use of
 *              this software, even if advised of the possibility of such
 *              damage.
 *
 * ////////////////////////////////////////////////////////////////////////// */



/** \file D/std/loader.d This file contains the \c D standard library 
 * executable module loader library, and the ExeModule class.
 */

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

module std.loader;

/* /////////////////////////////////////////////////////////////////////////////
 * Imports
 */

private import std.string;
private import std.c.stdlib;
private import std.c.stdio;
private import std.syserror;

//import synsoft.types;
/+ + These are borrowed from synsoft.types, until such time as something similar is in Phobos ++
 +/
public alias int                    boolean;

/* /////////////////////////////////////////////////////////////////////////////
 * External function declarations
 */

version(Windows)
{
    import std.c.windows.windows;

    extern(Windows)
    {
        alias HMODULE HModule_;
    }
}
else version(linux)
{
    extern(C)
    {
        const int RTLD_NOW  =   0x00002; /* Correct for Red Hat 8 */

        typedef void    *HModule_;

        HModule_    dlopen(char *path, int mode);
        int         dlclose(HModule_ handle);
        void        *dlsym(HModule_ handle, char *symbolName);
        char        *dlerror();
    }
}
else
{
	const int platform_not_discriminated = 0;

	static assert(platform_not_discriminated);
}

/** The platform-independent module handle. Note that this has to be
 * separate from the platform-dependent handle because different module names
 * can result in the same module being loaded, which cannot be detected in
 * some operating systems
 */
typedef void    *HXModule;

/* /////////////////////////////////////////////////////////////////////////////
 * ExeModule functions
 */

/* These are "forward declared" here because I don't like the way D forces me
 * to provide my declaration and implementation together, and mixed in with all
 * the other implementation gunk.
 */

/** ExeModule library Initialisation
 *
 * \retval <0 Initialisation failed. Processing must gracefully terminate, 
 * without making any use of the ExeModule library
 * \retval 0 Initialisation succeeded for the first time. Any necessary resources
 * were successfully allocated
 * \retval >0 Initialisation has already succeefully completed via a prior call.
 */
public int ExeModule_Init()
{
    return ExeModule_Init_();
}

public void ExeModule_Uninit()
{
    ExeModule_Uninit_();
}

/** 
 *
 * \note The value of the handle returned may not be a valid handle for your operating
 * system, and you <b>must not</b> attempt to use it with any other operating system
 * or other APIs. It is only valid for use with the ExeModule library.
 */
public HXModule ExeModule_Load(in char[] moduleName)
{
    return ExeModule_Load_(moduleName);
}

public HXModule ExeModule_AddRef(in HXModule hModule)
{
    return ExeModule_AddRef_(hModule);
}

/**
 *
 * \param hModule The module handler. It must not be null.
 */
public void ExeModule_Release(inout HXModule hModule)
{
    ExeModule_Release_(hModule);
}

public void *ExeModule_GetSymbol(inout HXModule hModule, in char[] symbolName)
{
    return ExeModule_GetSymbol_(hModule, symbolName);
}

public char[] ExeModule_Error()
{
    return ExeModule_Error_();
}


version(Windows)
{
    private int         s_init;
    private int         s_lastError;    // This is NOT thread-specific

    private void record_error_()
    {
        s_lastError = GetLastError();
    }


    private int ExeModule_Init_()
    {
        return ++s_init > 1;
    }

    private void ExeModule_Uninit_()
    {
        --s_init;
    }

    private HXModule ExeModule_Load_(in char[] moduleName)
    in
    {
        assert(null !== moduleName);
    }
    body
    {
        HXModule hmod = cast(HXModule)LoadLibraryA(toStringz(moduleName));

        if(null is hmod)
        {
            record_error_();
        }

        return hmod;
    }

    private HXModule ExeModule_AddRef_(in HXModule hModule)
    in
    {
        assert(null !== hModule);
    }
    body
    {
        return ExeModule_Load_(ExeModule_GetPath_(hModule));
    }

    private void ExeModule_Release_(inout HXModule hModule)
    in
    {
        assert(null !== hModule);
    }
    body
    {
        if(!FreeLibrary(cast(HModule_)hModule))
        {
            record_error_();
        }
        hModule = null;
    }

    private void *ExeModule_GetSymbol_(inout HXModule hModule, in char[] symbolName)
    in
    {
        assert(null !== hModule);
    }
    body
    {
        void    *symbol = GetProcAddress(cast(HModule_)hModule, toStringz(symbolName));

        if(null is symbol)
        {
            record_error_();
        }

        return symbol;
    }

    private char[] ExeModule_Error_()
    {
	return SysError.msg(s_lastError);
    }

    private char[] ExeModule_GetPath_(HXModule hModule)
    {
        char    szFileName[260]; // Need to use a constant here

	// http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/getmodulefilename.asp
        uint    cch = GetModuleFileNameA(cast(HModule_)hModule, szFileName, szFileName.length);

	if (cch == 0)
	{
            record_error_();
	}
        return szFileName[0 .. cch].dup;
    }
}
else version(linux)
{
    private class ExeModuleInfo
    {
    public:
        int         m_cRefs;
        HModule_    m_hmod;
        char[]      m_name;

        this(HModule_ hmod, char[] name)
        {
            m_cRefs =   1;
            m_hmod  =   hmod;
            m_name  =   name;
        }
    };

    private int                     s_init;
    private ExeModuleInfo [char[]]  s_modules;
    private char[]                  s_lastError;    // This is NOT thread-specific

    private void record_error_()
    {
        char *err = dlerror();
        s_lastError = (null is err) ? "" : err[0 .. std.string.strlen(err)];
    }

    private int ExeModule_Init_()
    {
        if(1 == ++s_init)
        {

            return 0;
        }

        return 1;
    }

    private void ExeModule_Uninit_()
    {
        if(0 == --s_init)
        {
        }
    }

    private HXModule ExeModule_Load_(in char[] moduleName)
    in
    {
        assert(null !== moduleName);
    }
    body
    {
        ExeModuleInfo   mi = s_modules[moduleName];

        if(null !== mi)
        {
            return (++mi.m_cRefs, cast(HXModule)mi);
        }
        else
        {
            HModule_    hmod = dlopen(toStringz(moduleName), RTLD_NOW);

            if(null is hmod)
            {
                record_error_();

                return null;
            }
            else
            {
                ExeModuleInfo   mi  =   new ExeModuleInfo(hmod, moduleName);

                s_modules[moduleName]   =   mi;

                return cast(HXModule)mi;
            }
        }
    }

    private HXModule ExeModule_AddRef_(in HXModule hModule)
    in
    {
        assert(null !== hModule);

        ExeModuleInfo   mi = cast(ExeModuleInfo)hModule;

        assert(0 < mi.m_cRefs);
        assert(null !== mi.m_hmod);
        assert(null !== mi.m_name);
        assert(null !== s_modules[mi.m_name]);
        assert(mi is s_modules[mi.m_name]);
    }
    body
    {
        ExeModuleInfo   mi = cast(ExeModuleInfo)hModule;

        if(null !== mi)
        {
            return (++mi.m_cRefs, hModule);
        }
        else
        {
            return null;
        }
    }

    private void ExeModule_Release_(inout HXModule hModule)
    in
    {
        assert(null !== hModule);

        ExeModuleInfo   mi = cast(ExeModuleInfo)hModule;

        assert(0 < mi.m_cRefs);
        assert(null !== mi.m_hmod);
        assert(null !== mi.m_name);
        assert(null !== s_modules[mi.m_name]);
        assert(mi is s_modules[mi.m_name]);
    }
    body
    {
        ExeModuleInfo   mi      =   cast(ExeModuleInfo)hModule;

        if(0 == --mi.m_cRefs)
        {
            char[]      name    =   mi.m_name;

            if (dlclose(mi.m_hmod))
            {
                record_error_();
            }
            delete s_modules[name];
            delete mi;
        }

        hModule = null;
    }

    private void *ExeModule_GetSymbol_(inout HXModule hModule, in char[] symbolName)
    in
    {
        assert(null !== hModule);

        ExeModuleInfo   mi = cast(ExeModuleInfo)hModule;

        assert(0 < mi.m_cRefs);
        assert(null !== mi.m_hmod);
        assert(null !== mi.m_name);
        assert(null !== s_modules[mi.m_name]);
        assert(mi is s_modules[mi.m_name]);
    }
    body
    {
        ExeModuleInfo   mi      =   cast(ExeModuleInfo)hModule;
        void *symbol = dlsym(mi.m_hmod, toStringz(symbolName));

        if(null == symbol)
        {
            record_error_();
        }

        return symbol;
    }

    private char[] ExeModule_Error_()
    {
        return s_lastError;
    }

    private char[] ExeModule_GetPath_(HXModule hModule)
    in
    {
        assert(null !== hModule);

        ExeModuleInfo   mi = cast(ExeModuleInfo)hModule;

        assert(0 < mi.m_cRefs);
        assert(null !== mi.m_hmod);
        assert(null !== mi.m_name);
        assert(null !== s_modules[mi.m_name]);
        assert(mi is s_modules[mi.m_name]);
    }
    body
    {
        ExeModuleInfo   mi = cast(ExeModuleInfo)hModule;

        return mi.m_name;
    }
}
else
{
	const int platform_not_discriminated = 0;

	static assert(platform_not_discriminated);
}

/* /////////////////////////////////////////////////////////////////////////////
 * Classes
 */

public class ExeModuleException
    : Exception
{
public:
    this(char[] message)
    {
        super(message);
    }

    this(uint errcode)
    {
	super(SysError.msg(errcode));
    }
}

/// This class represents an executable image
public auto class ExeModule
{
/// \name Construction
/// @{
public:
    /// Constructs from an existing image handle
    this(in HXModule hModule, boolean bTakeOwnership)
    in
    {
        assert(null !== hModule);
    }
    body
    {
        if(bTakeOwnership)
        {
            m_hModule = hModule;
        }
        else
        {
	    version (Windows)
	    {
		char[] path = Path();
		m_hModule = cast(HXModule)LoadLibraryA(toStringz(path));
		if (m_hModule == null)
		    throw new ExeModuleException(GetLastError());
	    }
	    else version (linux)
	    {
		m_hModule = ExeModule_AddRef(hModule);
	    }
	    else
		static assert(0);
        }
    }

    this(char[] moduleName)
    in
    {
        assert(null !== moduleName);
    }
    body
    {
	version (Windows)
	{
	    m_hModule = cast(HXModule)LoadLibraryA(toStringz(moduleName));
	    if (null is m_hModule)
		throw new ExeModuleException(GetLastError());
	}
	else version (linux)
	{
	    m_hModule = ExeModule_Load(moduleName);
	    if (null is m_hModule)
		throw new ExeModuleException(ExeModule_Error());
	}
	else
	{
	    static assert(0);		// unsupported system
	}
    }
    ~this()
    {
        close();
    }
/// @}

/// \name Operations
/// @{
public:
    /// Closes the library
    ///
    /// \note This is available to close the module at any time. Repeated
    /// calls do not result in an error, and are simply ignored.
    void close()
    {
        if(null !== m_hModule)
        {
	    version (Windows)
	    {
		if(!FreeLibrary(cast(HModule_)m_hModule))
		    throw new ExeModuleException(GetLastError());
	    }
	    else version (linux)
	    {
		ExeModule_Release(m_hModule);
	    }
	    else
		static assert(0);
        }
    }
/// @}

/// \name Accessors
/// @{
public:
    /** Retrieves the named symbol.
     *
     * \return A pointer to the symbol. There is no null return - failure to retrieve the symbol
     * results in an ExeModuleException exception being thrown.
     */
    void *getSymbol(in char[] symbolName)
    {
	version (Windows)
	{
	    void *symbol = GetProcAddress(cast(HModule_)m_hModule, toStringz(symbolName));
	    if(null is symbol)
	    {
		throw new ExeModuleException(GetLastError());
	    }
	}
	else version (linux)
	{
	    void *symbol = ExeModule_GetSymbol(m_hModule, symbolName);

	    if(null is symbol)
	    {
		throw new ExeModuleException(ExeModule_Error());
	    }
	}
	else
	{
	    static assert(0);
	}

        return symbol;
    }

    /** Retrieves the named symbol.
     *
     * \return A pointer to the symbol, or null if it does not exist
     */
    void *findSymbol(in char[] symbolName)
    {
        return ExeModule_GetSymbol(m_hModule, symbolName);
    }

/// @}

/// \name Properties
/// @{
public:
    /// The handle of the module
    ///
    /// \note Will be \c null if the module load in the constructor failed
    HXModule Handle()
    {
        return m_hModule;
    }
    /// The handle of the module
    ///
    /// \note Will be \c null if the module load in the constructor failed
    char[] Path()
    {
        assert(null != m_hModule);

	version (Windows)
	{
	    char szFileName[260]; // Need to use a constant here

	    // http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/getmodulefilename.asp
	    uint cch = GetModuleFileNameA(cast(HModule_)m_hModule, szFileName, szFileName.length);
	    if (cch == 0)
		throw new ExeModuleException(GetLastError());

	    return szFileName[0 .. cch].dup;
	}
	else version (linux)
	{
	    return ExeModule_GetPath_(m_hModule);
	}
	else
	    static assert(0);
    }
/// @}

private:
    HXModule m_hModule;
};

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

version(TestMain)
{
    int main(char[][] args)
    {
        if(args.length < 3)
        {
            printf("USAGE: <moduleName> <symbolName>\n");
        }
        else
        {
            char[]  moduleName  =   args[1];
            char[]  symbolName  =   args[2];

            try
            {
                auto ExeModule xmod =   new ExeModule(moduleName);

                printf("\"%.*s\" is loaded\n", moduleName);

                void    *symbol =   xmod.getSymbol(symbolName);

                if(null == symbol)
                {
                    throw new ExeModuleException(ExeModule_Error());
                }
                else
                {
                    printf("\"%.*s\" is acquired\n", symbolName);
                }
            }
            catch(ExeModuleException x)
            {
                x.print();
            }
        }

        return 0;
    }
}

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