/*++

Copyright (c) Microsoft Corporation.  All rights reserved.

Module Name:

    sputils.c

Abstract:

    Core sputils library file

Author:

    Jamie Hunter (JamieHun) Jun-27-2000

Revision History:

--*/

#include "precomp.h"
#pragma hdrstop

typedef ULONG (__cdecl *PFNDbgPrintEx)(IN ULONG ComponentId,IN ULONG Level,IN PCH Format, ...);
static PFNDbgPrintEx pfnDbgPrintEx = NULL;
static BOOL fInitDebug = FALSE;

static LONG RefCount = 0;                    // when this falls back to zero, release all resources
static BOOL SucceededInit = FALSE;

#define COUNTING 1

#if COUNTING
static DWORD pSpCheckHead = 0xaabbccdd;
static LONG pSpFailCount = 0;
static LONG pSpInitCount = 0;
static LONG pSpUninitCount = 0;
static LONG pSpConflictCount = 0;
static BOOL pSpDoneInit = FALSE;
static BOOL pSpFailedInit = FALSE;
static DWORD pSpCheckTail = 0xddccbbaa;
#endif

//
// At some point, a thread, process or module will call  pSetupInitializeUtils,
// and follow by a call to pSetupUninitializeUtils when done (cleanup)
//
// prior to this point, there's been no initialization other than static
// constants (above) pSetupInitializeUtils and pSetupUninitializeUtils must be
// mut-ex with each other and themselves
// thread A may call pSetupInitializeUtils while thread B is calling
// pSetupUninitializeUtils, the init in this case must succeed
// we can't use a single mutex or event object, since it must be cleaned up
// when pSetupUninitializeUtils succeeds
// we can't use a simple user-mode spin-lock, since priorities may be different,
// and it's just plain ugly using Sleep(0)
// so we have the _AcquireInitMutex and _ReleaseInitMutex implementations below
// it's guarenteed that when _AcquireInitMutex returns, it is not using any
// resources to hold the lock
// it will hold an event object if the thread is blocked, per blocked thread.
// This is ok since the number of blocked threads at any time will be few.
//
// It works as follows:
//
// a linked list of requests is maintained, with head at pWaitHead
// The head is interlocked, and when an item is inserted at pWaitHead
// it's entries must be valid, and can no longer be touched until
// the mutex is acquired.
//
// if the request is the very first, it need not block, will not block,
// as (at worst) the other thread has just removed it's request from the head
// and is about to return. The thread that inserts the first request into the
// list automatically owns the mutex.
//
// if the request is anything but the first, it will have an event object
// that will eventually be signalled, and at that point owns the mutex.
//
// the Thread that owns the mutex may modify anything on the wait-list,
// including pWaitHead.
//
// If the thread that owns the mutex is pWaitHead at the point it's releasing
// mutex, it does not need to signal anyone. This is protected by
// InterlockedCompareExchangePointer. If it finds itself in this state, the next
// pSetupInitializeUtils will automatically obtain the mutex, also protected
// by InterlockedCompareExchangePointer.
//
// If there are waiting entries in the list, then the tail-most waiting entry is
// signalled, at which point the related thread now owns the mutex.
//

#ifdef UNICODE

typedef struct _LinkWaitList {
    HANDLE hEvent; // for this item
    struct _LinkWaitList *pNext; // from Head to Tail
    struct _LinkWaitList *pPrev; // from Tail to Head
} LinkWaitList;

static LinkWaitList * pWaitHead = NULL;      // insert new wait items here

static
BOOL
_AcquireInitMutex(
    OUT LinkWaitList *pEntry
    )
/*++

Routine Description:

    Atomically acquire process mutex
    with no pre-requisite initialization other than
    static globals.
    Each blocked call will require an event to be created.

    Requests cannot be nested per thread (deadlock will occur)

Arguments:

    pEntry - structure to hold mutex information. This structure
                must persist until call to _ReleaseInitMutex.

    Global:pWaitHead - atomic linked list of mutex requests

Return Value:

    TRUE if mutex acquired.
    FALSE on failure (no resources)

--*/
{
    LinkWaitList *pTop;
    DWORD res;
    pEntry->pPrev = NULL;
    pEntry->pNext = NULL;
    pEntry->hEvent = NULL;
    //
    // fast lock, this will only succeed if we're the first and we have no reason to wait
    // this saves us needlessly creating an event
    //
    if(!InterlockedCompareExchangePointer(&pWaitHead,pEntry,NULL)) {
        return TRUE;
    }

#if COUNTING
    InterlockedIncrement(&pSpConflictCount);
#endif
    //
    // someone has (or, at least a moment ago, had) the lock, so we need an event
    //
    pEntry->hEvent = CreateEvent(NULL,FALSE,FALSE,NULL);
    if(!pEntry->hEvent) {
        return FALSE;
    }
    //
    // once pEntry is added to list, it cannot be touched until
    // WaitSingleObject is satisfied (unless we were the first)
    // if pWaitHead changes in the middle of the loop, we'll repeat again
    //
    do {
        pTop = pWaitHead;
        pEntry->pNext = pTop;
    } while (pTop != InterlockedCompareExchangePointer(&pWaitHead,pEntry,pTop));
    if(pTop) {
        //
        // we're not the first on the list
        // the owner of pTop will signal our event, wait for it.
        //
        res = WaitForSingleObject(pEntry->hEvent,INFINITE);
        pEntry->hEvent = NULL;
    }
    //
    // don't need event any more, the fact we've been signalled indicates we've now got the lock
    //
    CloseHandle(pEntry->hEvent);
    if(res != WAIT_OBJECT_0) {
        MYASSERT(res == WAIT_OBJECT_0);
        return FALSE;
    }
    return TRUE;
}

static
VOID
_ReleaseInitMutex(
    IN LinkWaitList *pEntry
    )
/*++

Routine Description:

    release process mutex previously acquired by _AcquireInitMutex
    thread must own the mutex
    no resources required for this action.
    This call may only be done once for each _AcquireInitMutex

Arguments:

    pEntry - holding mutex information. This structure
                must have been initialized by _AcquireInitMutex.

    Global:pWaitHead - atomic linked list of mutex requests

Return Value:

    none.

--*/
{
    LinkWaitList *pHead;
    LinkWaitList *pWalk;
    LinkWaitList *pPrev;

    MYASSERT(!pEntry->pNext);
    pHead = InterlockedCompareExchangePointer(&pWaitHead,NULL,pEntry);
    if(pHead == pEntry) {
        //
        // we were at head of list as well as at tail of list
        // list has now been reset to NULL
        // and may even already contain an entry due to a pLock call
        return;
    }
    if(!pEntry->pPrev) {
        //
        // we need to walk down list from pHead to pEntry
        // at the same time, remember back links
        // so we don't need to do this every time
        // note, we will never get here if pHead==pEntry
        //
        MYASSERT(pHead);
        MYASSERT(!pHead->pPrev);
        for(pWalk = pHead;pWalk != pEntry;pWalk = pWalk->pNext) {
            MYASSERT(pWalk->pNext);
            MYASSERT(!pWalk->pNext->pPrev);
            pWalk->pNext->pPrev = pWalk;
        }
    }
    pPrev = pEntry->pPrev;
    pPrev->pNext = NULL; // aids debugging, even in free build.
    SetEvent(pPrev->hEvent);
    return;
}

#else
//
// ANSI functions *MUST* work on Win95
// to support install of Whistler
// InterlockedCompareExchange(Pointer)
// is not supported
// so we'll use something simple/functional instead
// that uses the supported InterlockedExchange
//
static LONG SimpleCritSec = FALSE;
typedef PVOID LinkWaitList;

static
BOOL
_AcquireInitMutex(
    OUT LinkWaitList *pEntry
    )
{
    while(InterlockedExchange(&SimpleCritSec,TRUE) == TRUE) {
        //
        // release our timeslice
        // we should rarely be spinning here
        // starvation can occur in some circumstances
        // if initializing threads are of different priorities
        //
        Sleep(0);
    }
    return TRUE;
}

static
VOID
_ReleaseInitMutex(
    IN LinkWaitList *pEntry
    )
{
    if(InterlockedExchange(&SimpleCritSec,FALSE) == FALSE) {
        MYASSERT(0 && SimpleCritSec);
    }
}

#endif

BOOL
pSetupInitializeUtils(
    VOID
    )
/*++

Routine Description:

    Initialize this library
    balance each successful call to this function with
    equal number of calls to pSetupUninitializeUtils

Arguments:

    none

Return Value:

    TRUE if init succeeded, FALSE otherwise

--*/
{
    LinkWaitList Lock;

    if(!_AcquireInitMutex(&Lock)) {
#if COUNTING
        InterlockedIncrement(&pSpFailCount);
#endif
        return FALSE;
    }
#if COUNTING
    InterlockedIncrement(&pSpInitCount);
#endif
    RefCount++;
    if(RefCount==1) {
        pSpDoneInit = TRUE;
        SucceededInit = _pSpUtilsMemoryInitialize();
        if(!SucceededInit) {
            pSpFailedInit = TRUE;
            _pSpUtilsMemoryUninitialize();
        }
    }
    _ReleaseInitMutex(&Lock);
    return SucceededInit;
}

BOOL
pSetupUninitializeUtils(
    VOID
    )
/*++

Routine Description:

    Uninitialize this library
    This should be called for each successful call to
    pSetupInitializeUtils

Arguments:

    none

Return Value:

    TRUE if cleanup succeeded, FALSE otherwise

--*/
{
    LinkWaitList Lock;
#if COUNTING
    InterlockedIncrement(&pSpUninitCount);
#endif
    if(!SucceededInit) {
        return FALSE;
    }
    if(!_AcquireInitMutex(&Lock)) {
        return FALSE;
    }
    RefCount--;
    if(RefCount == 0) {
        _pSpUtilsMemoryUninitialize();
        SucceededInit = FALSE;
    }
    _ReleaseInitMutex(&Lock);
    return TRUE;
}

VOID
_pSpUtilsAssertFail(
    IN PSTR FileName,
    IN UINT LineNumber,
    IN PSTR Condition
    )
{
    int i;
    CHAR Name[MAX_PATH];
    PCHAR p;
    LPSTR Msg;
    DWORD msglen;
    DWORD sz;

    //
    // obtain module name
    //
    sz = GetModuleFileNameA(NULL,Name,MAX_PATH);
    if((sz == 0) || (sz > MAX_PATH)) {
        strcpy(Name,"?");
    }
    if(p = strrchr(Name,'\\')) {
        p++;
    } else {
        p = Name;
    }
    msglen = strlen(p)+strlen(FileName)+strlen(Condition)+128;
    //
    // assert might be out of memory condition
    // stack alloc is more likely to succeed than memory alloc
    //
    try {
        Msg = (LPSTR)_alloca(msglen);
        wsprintfA(
            Msg,
            "SPUTILS: Assertion failure at line %u in file %s!%s: %s\r\n",
            LineNumber,
            p,
            FileName,
            Condition
            );
    } except (EXCEPTION_EXECUTE_HANDLER) {
        Msg = "SpUTILS ASSERT!!!! (out of stack)\r\n";
    }

    OutputDebugStringA(Msg);
    DebugBreak();
}

VOID
pSetupDebugPrintEx(
    DWORD Level,
    PCTSTR format,
    ...                                 OPTIONAL
    )

/*++

Routine Description:

    Send a formatted string to the debugger.
    Note that this is expected to work cross-platform, but use preferred debugger

Arguments:

    format - standard printf format string.

Return Value:

    NONE.

--*/

{
    TCHAR buf[1026];    // bigger than max size
    va_list arglist;

    if (!fInitDebug) {
        pfnDbgPrintEx = (PFNDbgPrintEx)GetProcAddress(GetModuleHandle(TEXT("NTDLL")), "DbgPrintEx");
        fInitDebug = TRUE;
    }

    va_start(arglist, format);
    wvsprintf(buf, format, arglist);

    if (pfnDbgPrintEx) {
#ifdef UNICODE
        (*pfnDbgPrintEx)(DPFLTR_SETUP_ID, Level, "%ls",buf);
#else
        (*pfnDbgPrintEx)(DPFLTR_SETUP_ID, Level, "%s",buf);
#endif
    } else {
        OutputDebugString(buf);
    }
}