/* $Id: kLdrDyldSem.c 2 2007-11-16 16:07:14Z bird $ */
/** @file
 * kLdr - The Dynamic Loader, Semaphore Helper Functions.
 */

/*
 * Copyright (c) 2006-2007 knut st. osmundsen <bird-kStuff-spam@anduin.net>
 *
 * This file is part of kStuff.
 *
 * kStuff is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * In addition to the permissions in the GNU Lesser General Public
 * License, you are granted unlimited permission to link the compiled
 * version of this file into combinations with other programs, and to
 * distribute those combinations without any restriction coming from
 * the use of this file.
 *
 * kStuff 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with kStuff; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA
 */

/*******************************************************************************
*   Header Files                                                               *
*******************************************************************************/
#include <k/kDefs.h>
#include <k/kHlpSem.h>
#include <k/kHlpAssert.h>

#if K_OS == K_OS_DARWIN
# include <mach/mach.h>

#elif K_OS == K_OS_OS2
# define INCL_BASE
# define INCL_ERRORS
# include <os2.h>

#elif  K_OS == K_OS_WINDOWS
# include <Windows.h>

#else
# error "port me"
#endif



/*******************************************************************************
*   Global Variables                                                           *
*******************************************************************************/
#if K_OS == K_OS_DARWIN
/** The loader sempahore. */
static semaphore_t      g_Semaphore = MACH_PORT_NULL;

#elif K_OS == K_OS_OS2
/** The loader sempahore. */
static HMTX             g_hmtx;

#elif  K_OS == K_OS_WINDOWS
/** The loader sempahore. */
static CRITICAL_SECTION g_CritSect;

#else
# error "port me"
#endif


/**
 * Initializes the loader semaphore.
 *
 * @returns 0 on success, non-zero OS status code on failure.
 */
int kLdrDyldSemInit(void)
{
#if K_OS == K_OS_DARWIN
    kern_return_t krc;

    krc = semaphore_create(mach_task_self(), &g_Semaphore, SYNC_POLICY_FIFO, 0);
    if (krc != KERN_SUCCESS)
        return krc;

#elif K_OS == K_OS_OS2
    APIRET rc;
    g_hmtx = NULLHANDLE;
    rc = DosCreateMutexSem(NULL, &g_hmtx, 0, FALSE);
    if (rc)
        return rc;

#elif  K_OS == K_OS_WINDOWS
    InitializeCriticalSection(&g_CritSect);

#else
# error "port me"
#endif
    return 0;
}


/**
 * Terminates the loader semaphore.
 */
void kLdrDyldSemTerm(void)
{
#if K_OS == K_OS_DARWIN
    kern_return_t krc;
    semaphore_t Semaphore = g_Semaphore;
    g_Semaphore = MACH_PORT_NULL;
    krc = semaphore_destroy(mach_task_self(), Semaphore);
    kHlpAssert(krc == KERN_SUCCESS); (void)krc;

#elif K_OS == K_OS_OS2
    HMTX hmtx = g_hmtx;
    g_hmtx = NULLHANDLE;
    DosCloseMutexSem(hmtx);

#elif  K_OS == K_OS_WINDOWS
    DeleteCriticalSection(&g_CritSect);

#else
# error "port me"
#endif
}


/**
 * Requests the loader sempahore ownership.
 * This can be done recursivly.
 *
 * @returns 0 on success, non-zero OS status code on failure.
 */
int kLdrDyldSemRequest(void)
{
#if K_OS == K_OS_DARWIN
    /* not sure about this... */
    kern_return_t krc;
    do krc = semaphore_wait(g_Semaphore);
    while (krc == KERN_ABORTED);
    if (krc == KERN_SUCCESS)
        return 0;
    return krc;

#elif K_OS == K_OS_OS2
    APIRET rc = DosRequestMutexSem(g_hmtx, 5000);
    if (rc == ERROR_TIMEOUT || rc == ERROR_SEM_TIMEOUT || rc == ERROR_INTERRUPT)
    {
        unsigned i = 0;
        do
        {
            /** @todo check for deadlocks etc. */
            rc = DosRequestMutexSem(g_hmtx, 1000);
        } while (   (   rc == ERROR_TIMEOUT
                     || rc == ERROR_SEM_TIMEOUT
                     || rc == ERROR_INTERRUPT)
                 && i++ < 120);
    }
    return rc;

#elif  K_OS == K_OS_WINDOWS
    EnterCriticalSection(&g_CritSect);
    return 0;

#else
# error "port me"
#endif
}


/**
 * Releases the loader semaphore ownership.
 * The caller is responsible for making sure it's the semaphore owner!
 */
void kLdrDyldSemRelease(void)
{
#if K_OS == K_OS_DARWIN
    /* not too sure about this... */
    kern_return_t krc = semaphore_signal(g_Semaphore);
    kHlpAssert(krc == KERN_SUCCESS); (void)krc;

#elif K_OS == K_OS_OS2
    APIRET rc = DosReleaseMutexSem(g_hmtx);
    kHlpAssert(!rc); (void)rc;

#elif  K_OS == K_OS_WINDOWS
    LeaveCriticalSection(&g_CritSect);

#else
# error "port me"
#endif
}