/* $Id: kLdr.c 2883 2006-11-18 11:21:33Z bird $ */
/** @file
 *
 * kLdr - The Dynamic Loader.
 *
 * Copyright (c) 2006 knut st. osmundsen <bird@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
 *
 */

/** @mainpage   kLdr - The Dynamic Loader
 *
 * The purpose of kLdr is to provide a generic interface for querying
 * information about and loading executable image modules.
 *
 * kLdr defines the term executable image to include all kinds of files that contains
 * binary code that can be executed on a CPU - linker objects (OBJs/Os), shared
 * objects (SOs), dynamic link libraries (DLLs), executables (EXEs), and all kinds
 * of kernel modules / device drivers (SYSs).
 *
 * kLdr provides two types of services:
 *      -# Inspect or/and load individual modules (kLdrMod).
 *      -# Work as a dynamic loader - construct and maintain an address space (kLdrDy).
 *
 * The kLdrMod API works on KLDRMOD structures where all the internals are exposed, while
 * the kLdrDy API works opque KLDRDY structures. KLDRDY are in reality simple wrappers
 * around KLDRMOD with some extra linking and attributes.
 *
 */




/*******************************************************************************
*   Header Files                                                               *
*******************************************************************************/
#include "kLdr.h"
#include "kLdrHlp.h"
#include "kLdrInternal.h"


/*******************************************************************************
*   Global Variables                                                           *
*******************************************************************************/
/** Flag indicating whether we've initialized the loader or not.
 *
 * 0 if not initialized.
 * -1 if we're initializing or terminating.
 * 1 if we've successfully initialized it.
 * -2 if initialization failed.
 */
static int volatile g_fInitialized;



/**
 * Initializes the loader.
 * @returns 0 on success, non-zero OS status code on failure.
 */
int kldrInit(void)
{
    int rc;

    /* check we're already good. */
    if (g_fInitialized == 1)
        return 0;

    /* a tiny serialization effort. */
    for (;;)
    {
        if (g_fInitialized == 1)
            return 0;
        if (g_fInitialized == -2)
            return -1;
        /** @todo atomic test and set if we care. */
        if (g_fInitialized == 0)
        {
            g_fInitialized = -1;
            break;
        }
        kldrHlpSleep(1);
    }

    /*
     * Do the initialization.
     */
    rc = kldrHlpHeapInit();
    if (!rc)
    {
        rc = kldrHlpSemInit();
        if (!rc)
        {
            rc = kldrDyldInit();
            if (!rc)
            {
                g_fInitialized = 1;
                return 0;
            }
            kldrHlpSemTerm();
        }
        kldrHlpHeapTerm();
    }
    g_fInitialized = -2;
    return rc;
}


/**
 * Terminates the loader.
 */
void kldrTerm(void)
{
    /* can't terminate unless it's initialized. */
    if (g_fInitialized != 1)
        return;
    g_fInitialized = -1;

    /*
     * Do the termination.
     */
    kldrHlpSemTerm();
    kldrHlpHeapTerm();

    /* done */
    g_fInitialized = 0;
}


/**
 * Compares arch+cpu some code was generated for with a arch+cpu for executing it
 * to see if it'll work out fine or not.
 *
 * @returns 0 if the code is compatible with the cpu.
 * @returns KLDR_ERR_ARCH_CPU_NOT_COMPATIBLE if the arch+cpu isn't compatible with the code.
 * @param   enmCodeArch The architecture the code was generated for.
 * @param   enmCodeCpu  The cpu the code was generated for.
 * @param   enmArch     The architecture to run it on.
 * @param   enmCpu      The cpu to run it on.
 */
int kLdrCompareCpus(KLDRARCH enmCodeArch, KLDRCPU enmCodeCpu, KLDRARCH enmArch, KLDRCPU enmCpu)
{
    /*
     * Compare arch and cpu.
     */
    if (enmCodeArch != enmArch)
        return KLDR_ERR_ARCH_CPU_NOT_COMPATIBLE;

    /* exact match is nice. */
    if (enmCodeCpu == enmCpu)
        return 0;
    switch (enmArch)
    {
        case KLDRARCH_X86_16:
            if (enmCpu < KLDRCPU_FIRST_X86_16 || enmCpu > KLDRCPU_LAST_X86_16)
                return KLDR_ERR_INVALID_PARAMETER;

            /* intel? */
            if (enmCodeCpu <= KLDRCPU_CORE2_16)
            {
                /* also intel? */
                if (enmCpu <= KLDRCPU_CORE2_16)
                    return enmCodeCpu <= enmCpu ? 0 : KLDR_ERR_ARCH_CPU_NOT_COMPATIBLE;
                switch (enmCpu)
                {
                    case KLDRCPU_K6_16:
                        return enmCodeCpu <= KLDRCPU_I586 ? 0 : KLDR_ERR_ARCH_CPU_NOT_COMPATIBLE;
                    case KLDRCPU_K7_16:
                    case KLDRCPU_K8_16:
                    default:
                        return enmCodeCpu <= KLDRCPU_I686 ? 0 : KLDR_ERR_ARCH_CPU_NOT_COMPATIBLE;
                }
            }
            /* amd */
            return enmCpu >= KLDRCPU_K6_16 && enmCpu <= KLDRCPU_K8_16
                    ? 0 : KLDR_ERR_ARCH_CPU_NOT_COMPATIBLE;

        case KLDRARCH_X86_32:
            if (enmCpu < KLDRCPU_FIRST_X86_32 || enmCpu > KLDRCPU_LAST_X86_32)
                return KLDR_ERR_INVALID_PARAMETER;

            /* blend? */
            if (enmCodeCpu == KLDRCPU_X86_32_BLEND)
                return 0;

            /* intel? */
            if (enmCodeCpu <= KLDRCPU_CORE2_32)
            {
                /* also intel? */
                if (enmCpu <= KLDRCPU_CORE2_32)
                    return enmCodeCpu <= enmCpu ? 0 : KLDR_ERR_ARCH_CPU_NOT_COMPATIBLE;
                switch (enmCpu)
                {
                    case KLDRCPU_K6:
                        return enmCodeCpu <= KLDRCPU_I586 ? 0 : KLDR_ERR_ARCH_CPU_NOT_COMPATIBLE;
                    case KLDRCPU_K7:
                    case KLDRCPU_K8_32:
                    default:
                        return enmCodeCpu <= KLDRCPU_I686 ? 0 : KLDR_ERR_ARCH_CPU_NOT_COMPATIBLE;
                }
            }
            /* amd */
            return enmCpu >= KLDRCPU_K6 && enmCpu <= KLDRCPU_K8_32
                    ? 0 : KLDR_ERR_ARCH_CPU_NOT_COMPATIBLE;

        case KLDRARCH_AMD64:
            if (enmCpu < KLDRCPU_FIRST_AMD64 || enmCpu > KLDRCPU_LAST_AMD64)
                return KLDR_ERR_INVALID_PARAMETER;

            /* blend? */
            if (enmCodeCpu == KLDRCPU_AMD64_BLEND)
                return 0;
            /* this is simple for now. */
            return KLDR_ERR_ARCH_CPU_NOT_COMPATIBLE;

        default:
            break;
    }
    return KLDR_ERR_ARCH_CPU_NOT_COMPATIBLE;
}


/**
 * Gets the arch+cpu of the calling cpu.
 *
 * @param   penmArch    Where to store the cpu architecture.
 * @param   penmCpu     Where to store the cpu brand/model.
 */
void kLdrGetArchCpu(PKLDRARCH penmArch, PKLDRCPU penmCpu)
{
#ifdef __AMD64__
    *penmArch = KLDRARCH_AMD64;
    *penmCpu = KLDRCPU_AMD64_BLEND; /** @todo check it using cpu. */

#elif defined(__X86__)
    *penmArch = KLDRARCH_X86_32;
    *penmCpu = KLDRCPU_X86_32_BLEND; /** @todo check it using cpu. */

#else
# error "Port me"
#endif
}