/* $Id: kLdrMod.c 2827 2006-10-22 18:05:28Z bird $ */
/** @file
 *
 * kLdr - The Dynamic Loader, The module interpreter.
 *
 * Copyright (c) 2006 knut st. osmundsen <bird-kbuild-src@anduin.net>
 *
 *
 * This file is part of kLdr.
 *
 * kLdr is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * kLdr 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 kLdr; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */


/*******************************************************************************
*   Header Files                                                               *
*******************************************************************************/
#include <kLdr.h>
#include "kLdrHlp.h"
#include "kLdrInternal.h"
#include "kLdrModMZ.h"
#if 1 /* testing headers */
# include "kLdrModPE.h"
//# include "kLdrModLX.h"
# include "kLdrModELF32.h"
# include "kLdrModELF64.h"
#endif


/**
 * Open a executable image from a file provider instance.
 *
 * @returns 0 on success and *ppMod pointing to a module instance.
 *          On failure, a non-zero OS specific error code is returned.
 * @param   pRdr            The file provider instance to use.
 *                          On success, the ownership of the instance is taken by the
 *                          module and the caller must not ever touch it again.
 *                          (The instance is not closed on failure, the call has to do that.)
 * @param   ppMod           Where to store the module handle.
 */
int kLdrModOpenFromRdr(PKLDRRDR pRdr, PPKLDRMOD ppMod)
{
    union
    {
        uint32_t    u32;
        uint16_t    u16;
        uint16_t    au16[2];
        uint8_t     au8[4];
    }       u;
    off_t   offHdr = 0;
    int     rc;

    /*
     * Try figure out what kind of image this is.
     * Always read the 'new header' if we encounter MZ.
     */
    rc = kLdrRdrRead(pRdr, &u, sizeof(u), 0);
    if (rc)
        return rc;
    if (    u.u16 == IMAGE_DOS_SIGNATURE
        &&  kLdrRdrSize(pRdr) > sizeof(IMAGE_DOS_HEADER))
    {
        rc = kLdrRdrRead(pRdr, &u, sizeof(u.u32), KLDR_OFFSETOF(IMAGE_DOS_HEADER, e_lfanew));
        if (rc)
            return rc;
        if ((off_t)u.u32 < kLdrRdrSize(pRdr))
        {
            offHdr = u.u32;
            rc = kLdrRdrRead(pRdr, &u, sizeof(u.u32), offHdr);
            if (rc)
                return rc;
        }
        else
            u.u16 = IMAGE_DOS_SIGNATURE;
    }

    /*
     * Use the magic to select the appropriate image interpreter.
     */
    if (u.u16 == IMAGE_DOS_SIGNATURE)
        return KLDR_ERR_MZ_NOT_SUPPORTED;
    else if (u.u16 == IMAGE_NE_SIGNATURE)
        return KLDR_ERR_NE_NOT_SUPPORTED;
    else if (u.u16 == IMAGE_LX_SIGNATURE)
        return KLDR_ERR_LX_NOT_SUPPORTED;
    else if (u.u16 == IMAGE_LE_SIGNATURE)
        return KLDR_ERR_LE_NOT_SUPPORTED;
    else if (u.u32 == IMAGE_NT_SIGNATURE)
        return KLDR_ERR_PE_NOT_SUPPORTED;
    else if (u.u32 == IMAGE_ELF_SIGNATURE)
        return KLDR_ERR_ELF_NOT_SUPPORTED;
    return KLDR_ERR_UNKNOWN_FORMAT;
}


/**
 * Open a executable image by file name.
 *
 * @returns 0 on success and *ppMod pointing to a module instance.
 *          On failure, a non-zero OS specific error code is returned.
 * @param   pszFilename     The filename to open.
 * @param   ppMod           Where to store the module handle.
 */
int kLdrModOpen(const char *pszFilename, PPKLDRMOD ppMod)
{
    /*
     * Open the file using a bit provider.
     */
    PKLDRRDR pRdr;
    int rc = kLdrRdrOpen(&pRdr, pszFilename);
    if (!rc)
    {
        rc = kLdrModOpenFromRdr(pRdr, ppMod);
        if (!rc)
            return 0;
       kLdrRdrClose(pRdr);
    }
    return rc;
}