#endif
#ifndef SQLITE_WIN32_IOERR_RETRY_DELAY
# define SQLITE_WIN32_IOERR_RETRY_DELAY 25
#endif
static int winIoerrRetry = SQLITE_WIN32_IOERR_RETRY;
static int winIoerrRetryDelay = SQLITE_WIN32_IOERR_RETRY_DELAY;












/*
** The "winIoerrCanRetry1" macro is used to determine if a particular I/O
** error code obtained via GetLastError() is eligible to be retried.  It
** must accept the error code DWORD as its only argument and should return
** non-zero if the error code is transient in nature and the operation
** responsible for generating the original error might succeed upon being
** retried.  The argument to this macro should be a variable.
................................................................................
struct winShmNode {
  sqlite3_mutex *mutex;      /* Mutex to access this object */
  char *zFilename;           /* Name of the file */
  winFile hFile;             /* File handle from winOpen */

  int szRegion;              /* Size of shared-memory regions */
  int nRegion;               /* Size of array apRegion */



  struct ShmRegion {
    HANDLE hMap;             /* File handle from CreateFileMapping */
    void *pMap;
  } *aRegion;
  DWORD lastErrno;           /* The Windows errno from the last I/O error */

  int nRef;                  /* Number of winShm objects pointing to this */
................................................................................
      sqlite3_free(p->aRegion);
      sqlite3_free(p);
    }else{
      pp = &p->pNext;
    }
  }
}

/*














































































































** Open the shared-memory area associated with database file pDbFd.
**
** When opening a new shared-memory file, if no other instances of that
** file are currently open, in this process or in other processes, then
** the file must be truncated to zero length or have its header cleared.
*/
static int winOpenSharedMemory(winFile *pDbFd){
  struct winShm *p;                  /* The connection to be opened */
  struct winShmNode *pShmNode = 0;   /* The underlying mmapped file */
  int rc;                            /* Result code */

  struct winShmNode *pNew;           /* Newly allocated winShmNode */
  int nName;                         /* Size of zName in bytes */

  assert( pDbFd->pShm==0 );    /* Not previously opened */

  /* Allocate space for the new sqlite3_shm object.  Also speculatively
  ** allocate space for a new winShmNode and filename.
  */
  p = sqlite3MallocZero( sizeof(*p) );
................................................................................
      pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
      if( pShmNode->mutex==0 ){
        rc = SQLITE_IOERR_NOMEM_BKPT;
        goto shm_open_err;
      }
    }

    rc = winOpen(pDbFd->pVfs,
                 pShmNode->zFilename,             /* Name of the file (UTF-8) */
                 (sqlite3_file*)&pShmNode->hFile,  /* File handle here */
                 SQLITE_OPEN_WAL | SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE,
                 0);
    if( SQLITE_OK!=rc ){
      goto shm_open_err;
    }

    /* Check to see if another process is holding the dead-man switch.
    ** If not, truncate the file to zero length.
    */
    if( winShmSystemLock(pShmNode, WINSHM_WRLCK, WIN_SHM_DMS, 1)==SQLITE_OK ){
      rc = winTruncate((sqlite3_file *)&pShmNode->hFile, 0);
      if( rc!=SQLITE_OK ){
        rc = winLogError(SQLITE_IOERR_SHMOPEN, osGetLastError(),
                         "winOpenShm", pDbFd->zPath);
      }
    }
    if( rc==SQLITE_OK ){
      winShmSystemLock(pShmNode, WINSHM_UNLCK, WIN_SHM_DMS, 1);
      rc = winShmSystemLock(pShmNode, WINSHM_RDLCK, WIN_SHM_DMS, 1);
    }
    if( rc ) goto shm_open_err;
  }

  /* Make the new connection a child of the winShmNode */
  p->pShmNode = pShmNode;
#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
  p->id = pShmNode->nextShmId++;
#endif
................................................................................
  int szRegion,                   /* Size of regions */
  int isWrite,                    /* True to extend file if necessary */
  void volatile **pp              /* OUT: Mapped memory */
){
  winFile *pDbFd = (winFile*)fd;
  winShm *pShm = pDbFd->pShm;
  winShmNode *pShmNode;


  int rc = SQLITE_OK;

  if( !pShm ){
    rc = winOpenSharedMemory(pDbFd);
    if( rc!=SQLITE_OK ) return rc;
    pShm = pDbFd->pShm;
  }
  pShmNode = pShm->pShmNode;

  sqlite3_mutex_enter(pShmNode->mutex);





  assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 );

  if( pShmNode->nRegion<=iRegion ){
    struct ShmRegion *apNew;           /* New aRegion[] array */
    int nByte = (iRegion+1)*szRegion;  /* Minimum required file size */
    sqlite3_int64 sz;                  /* Current size of wal-index file */

................................................................................
        pShmNode->aRegion, (iRegion+1)*sizeof(apNew[0])
    );
    if( !apNew ){
      rc = SQLITE_IOERR_NOMEM_BKPT;
      goto shmpage_out;
    }
    pShmNode->aRegion = apNew;






    while( pShmNode->nRegion<=iRegion ){
      HANDLE hMap = NULL;         /* file-mapping handle */
      void *pMap = 0;             /* Mapped memory region */

#if SQLITE_OS_WINRT
      hMap = osCreateFileMappingFromApp(pShmNode->hFile.h,
          NULL, PAGE_READWRITE, nByte, NULL
      );
#elif defined(SQLITE_WIN32_HAS_WIDE)
      hMap = osCreateFileMappingW(pShmNode->hFile.h,
          NULL, PAGE_READWRITE, 0, nByte, NULL
      );
#elif defined(SQLITE_WIN32_HAS_ANSI) && SQLITE_WIN32_CREATEFILEMAPPINGA
      hMap = osCreateFileMappingA(pShmNode->hFile.h,
          NULL, PAGE_READWRITE, 0, nByte, NULL
      );
#endif
      OSTRACE(("SHM-MAP-CREATE pid=%lu, region=%d, size=%d, rc=%s\n",
               osGetCurrentProcessId(), pShmNode->nRegion, nByte,
               hMap ? "ok" : "failed"));
      if( hMap ){
        int iOffset = pShmNode->nRegion*szRegion;
        int iOffsetShift = iOffset % winSysInfo.dwAllocationGranularity;
#if SQLITE_OS_WINRT
        pMap = osMapViewOfFileFromApp(hMap, FILE_MAP_WRITE | FILE_MAP_READ,
            iOffset - iOffsetShift, szRegion + iOffsetShift
        );
#else
        pMap = osMapViewOfFile(hMap, FILE_MAP_WRITE | FILE_MAP_READ,
            0, iOffset - iOffsetShift, szRegion + iOffsetShift
        );
#endif
        OSTRACE(("SHM-MAP-MAP pid=%lu, region=%d, offset=%d, size=%d, rc=%s\n",
                 osGetCurrentProcessId(), pShmNode->nRegion, iOffset,
                 szRegion, pMap ? "ok" : "failed"));
      }
................................................................................
    int iOffset = iRegion*szRegion;
    int iOffsetShift = iOffset % winSysInfo.dwAllocationGranularity;
    char *p = (char *)pShmNode->aRegion[iRegion].pMap;
    *pp = (void *)&p[iOffsetShift];
  }else{
    *pp = 0;
  }

  sqlite3_mutex_leave(pShmNode->mutex);
  return rc;
}

#else
# define winShmMap     0
# define winShmLock    0

#endif
#ifndef SQLITE_WIN32_IOERR_RETRY_DELAY
# define SQLITE_WIN32_IOERR_RETRY_DELAY 25
#endif
static int winIoerrRetry = SQLITE_WIN32_IOERR_RETRY;
static int winIoerrRetryDelay = SQLITE_WIN32_IOERR_RETRY_DELAY;

/*
** The "winIsLockingError" macro is used to determine if a particular I/O
** error code is due to file locking.  It must accept the error code DWORD
** as its only argument and should return non-zero if the error code is due
** to file locking.
*/
#if !defined(winIsLockingError)
#define winIsLockingError(a) (((a)==ERROR_LOCK_VIOLATION)       || \
                              ((a)==ERROR_IO_PENDING))
#endif

/*
** The "winIoerrCanRetry1" macro is used to determine if a particular I/O
** error code obtained via GetLastError() is eligible to be retried.  It
** must accept the error code DWORD as its only argument and should return
** non-zero if the error code is transient in nature and the operation
** responsible for generating the original error might succeed upon being
** retried.  The argument to this macro should be a variable.
................................................................................
struct winShmNode {
  sqlite3_mutex *mutex;      /* Mutex to access this object */
  char *zFilename;           /* Name of the file */
  winFile hFile;             /* File handle from winOpen */

  int szRegion;              /* Size of shared-memory regions */
  int nRegion;               /* Size of array apRegion */
  u8 isReadonly;             /* True if read-only */
  u8 isUnlocked;             /* True if no DMS lock held */

  struct ShmRegion {
    HANDLE hMap;             /* File handle from CreateFileMapping */
    void *pMap;
  } *aRegion;
  DWORD lastErrno;           /* The Windows errno from the last I/O error */

  int nRef;                  /* Number of winShm objects pointing to this */
................................................................................
      sqlite3_free(p->aRegion);
      sqlite3_free(p);
    }else{
      pp = &p->pNext;
    }
  }
}

/*
** Query the status of the DMS lock for the specified file.  Returns
** SQLITE_OK upon success.  Upon success, the integer pointed to by
** the pLockType argument will be set to the lock type held by the
** other process, as follows:
**
**       WINSHM_UNLCK -- No locks are held on the DMS.
**       WINSHM_RDLCK -- A SHARED lock is held on the DMS.
**       WINSHM_WRLCK -- An EXCLUSIVE lock is held on the DMS.
*/
static int winGetShmDmsLockType(
  winFile *pFile, /* File handle object */
  int *pLockType  /* WINSHM_UNLCK, WINSHM_RDLCK, or WINSHM_WRLCK */
){
#if !SQLITE_OS_WINCE && !defined(SQLITE_WIN32_NO_OVERLAPPED)
  OVERLAPPED overlapped; /* The offset for ReadFile/WriteFile. */
#endif
  LPVOID pOverlapped = 0;
  sqlite3_int64 offset = WIN_SHM_DMS;
  BYTE notUsed1 = 0;
  DWORD notUsed2 = 0;

#if SQLITE_OS_WINCE || defined(SQLITE_WIN32_NO_OVERLAPPED)
  if( winSeekFile(pFile, offset) ){
    return SQLITE_IOERR_SEEK;
  }
#else
  memset(&overlapped, 0, sizeof(OVERLAPPED));
  overlapped.Offset = (LONG)(offset & 0xffffffff);
  overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);
  pOverlapped = &overlapped;
#endif
  if( !osWriteFile(pFile->h, &notUsed1, 1, &notUsed2, pOverlapped) ){
    if( !osReadFile(pFile->h, &notUsed1, 1, &notUsed2, pOverlapped) ){
      if( winIsLockingError(osGetLastError()) ){
        *pLockType = WINSHM_WRLCK;
      }else{
        return SQLITE_IOERR_READ;
      }
    }else{
      if( winIsLockingError(osGetLastError()) ){
        *pLockType = WINSHM_RDLCK;
      }else{
        return SQLITE_IOERR_WRITE;
      }
    }
  }else{
    *pLockType = WINSHM_UNLCK;
  }
  return SQLITE_OK;
}

/*
** The DMS lock has not yet been taken on shm file pShmNode. Attempt to
** take it now. Return SQLITE_OK if successful, or an SQLite error
** code otherwise.
**
** If the DMS cannot be locked because this is a readonly_shm=1
** connection and no other process already holds a lock, return
** SQLITE_READONLY_CANTINIT and set pShmNode->isUnlocked=1.
*/
static int winLockSharedMemory(winFile *pDbFd, winShmNode *pShmNode){
  int lockType;
  int rc = SQLITE_OK;

  /* Use ReadFile/WriteFile to determine the locks other processes are
  ** holding on the DMS byte. If it indicates that another process is
  ** holding a SHARED lock, then this process may also take a SHARED
  ** lock and proceed with opening the *-shm file.
  **
  ** Or, if no other process is holding any lock, then this process
  ** is the first to open it. In this case take an EXCLUSIVE lock on the
  ** DMS byte and truncate the *-shm file to zero bytes in size. Then
  ** downgrade to a SHARED lock on the DMS byte.
  **
  ** If another process is holding an EXCLUSIVE lock on the DMS byte,
  ** return SQLITE_BUSY to the caller (it will try again). An earlier
  ** version of this code attempted the SHARED lock at this point. But
  ** this introduced a subtle race condition: if the process holding
  ** EXCLUSIVE failed just before truncating the *-shm file, then this
  ** process might open and use the *-shm file without truncating it.
  ** And if the *-shm file has been corrupted by a power failure or
  ** system crash, the database itself may also become corrupt.  */
  if( winGetShmDmsLockType(&pShmNode->hFile, &lockType)!=SQLITE_OK ){
    rc = SQLITE_IOERR_LOCK;
  }else if( lockType==WINSHM_UNLCK ){
    if( pShmNode->isReadonly ){
      pShmNode->isUnlocked = 1;
      rc = SQLITE_READONLY_CANTINIT;
    }else{
      winShmSystemLock(pShmNode, WINSHM_UNLCK, WIN_SHM_DMS, 1);
      rc = winShmSystemLock(pShmNode, WINSHM_WRLCK, WIN_SHM_DMS, 1);
      if( rc==SQLITE_OK && winTruncate((sqlite3_file*)&pShmNode->hFile, 0) ){
        rc = winLogError(SQLITE_IOERR_SHMOPEN, osGetLastError(),
                         "winLockSharedMemory", pShmNode->zFilename);
      }
    }
  }else if( lockType==WINSHM_WRLCK ){
    rc = SQLITE_BUSY;
  }

  if( rc==SQLITE_OK ){
    assert( lockType==WINSHM_UNLCK || lockType==WINSHM_RDLCK );
    winShmSystemLock(pShmNode, WINSHM_UNLCK, WIN_SHM_DMS, 1);
    rc = winShmSystemLock(pShmNode, WINSHM_RDLCK, WIN_SHM_DMS, 1);
  }

  return rc;
}

/*
** Open the shared-memory area associated with database file pDbFd.
**
** When opening a new shared-memory file, if no other instances of that
** file are currently open, in this process or in other processes, then
** the file must be truncated to zero length or have its header cleared.
*/
static int winOpenSharedMemory(winFile *pDbFd){
  struct winShm *p;         /* The connection to be opened */
  winShmNode *pShmNode = 0; /* The underlying mmapped file */
  int rc = SQLITE_OK;       /* Result code */
  int rc2 = SQLITE_ERROR;   /* winOpen result code */
  winShmNode *pNew;         /* Newly allocated winShmNode */
  int nName;                /* Size of zName in bytes */

  assert( pDbFd->pShm==0 );    /* Not previously opened */

  /* Allocate space for the new sqlite3_shm object.  Also speculatively
  ** allocate space for a new winShmNode and filename.
  */
  p = sqlite3MallocZero( sizeof(*p) );
................................................................................
      pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
      if( pShmNode->mutex==0 ){
        rc = SQLITE_IOERR_NOMEM_BKPT;
        goto shm_open_err;
      }
    }

    if( 0==sqlite3_uri_boolean(pDbFd->zPath, "readonly_shm", 0) ){
      rc2 = winOpen(pDbFd->pVfs,
                    pShmNode->zFilename,
                    (sqlite3_file*)&pShmNode->hFile,
                    SQLITE_OPEN_WAL|SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE,
                    0);
    }
    if( rc2!=SQLITE_OK ){
      rc2 = winOpen(pDbFd->pVfs,
                    pShmNode->zFilename,
                    (sqlite3_file*)&pShmNode->hFile,
                    SQLITE_OPEN_WAL|SQLITE_OPEN_READONLY|SQLITE_OPEN_CREATE,
                    0);
      if( rc2!=SQLITE_OK ){
        rc = winLogError(SQLITE_CANTOPEN_BKPT, osGetLastError(),
                         "winOpenShm", pShmNode->zFilename);
        goto shm_open_err;
      }
      pShmNode->isReadonly = 1;
    }

    rc = winLockSharedMemory(pDbFd, pShmNode);
    if( rc!=SQLITE_OK && rc!=SQLITE_READONLY_CANTINIT ) goto shm_open_err;

  }

  /* Make the new connection a child of the winShmNode */
  p->pShmNode = pShmNode;
#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
  p->id = pShmNode->nextShmId++;
#endif
................................................................................
  int szRegion,                   /* Size of regions */
  int isWrite,                    /* True to extend file if necessary */
  void volatile **pp              /* OUT: Mapped memory */
){
  winFile *pDbFd = (winFile*)fd;
  winShm *pShm = pDbFd->pShm;
  winShmNode *pShmNode;
  DWORD protect = PAGE_READWRITE;
  DWORD flags = FILE_MAP_WRITE | FILE_MAP_READ;
  int rc = SQLITE_OK;

  if( !pShm ){
    rc = winOpenSharedMemory(pDbFd);
    if( rc!=SQLITE_OK ) return rc;
    pShm = pDbFd->pShm;
  }
  pShmNode = pShm->pShmNode;

  sqlite3_mutex_enter(pShmNode->mutex);
  if( pShmNode->isUnlocked ){
    rc = winLockSharedMemory(pDbFd, pShmNode);
    if( rc!=SQLITE_OK ) goto shmpage_out;
    pShmNode->isUnlocked = 0;
  }
  assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 );

  if( pShmNode->nRegion<=iRegion ){
    struct ShmRegion *apNew;           /* New aRegion[] array */
    int nByte = (iRegion+1)*szRegion;  /* Minimum required file size */
    sqlite3_int64 sz;                  /* Current size of wal-index file */

................................................................................
        pShmNode->aRegion, (iRegion+1)*sizeof(apNew[0])
    );
    if( !apNew ){
      rc = SQLITE_IOERR_NOMEM_BKPT;
      goto shmpage_out;
    }
    pShmNode->aRegion = apNew;

    if( pShmNode->isReadonly ){
      protect = PAGE_READONLY;
      flags = FILE_MAP_READ;
    }

    while( pShmNode->nRegion<=iRegion ){
      HANDLE hMap = NULL;         /* file-mapping handle */
      void *pMap = 0;             /* Mapped memory region */

#if SQLITE_OS_WINRT
      hMap = osCreateFileMappingFromApp(pShmNode->hFile.h,
          NULL, protect, nByte, NULL
      );
#elif defined(SQLITE_WIN32_HAS_WIDE)
      hMap = osCreateFileMappingW(pShmNode->hFile.h,
          NULL, protect, 0, nByte, NULL
      );
#elif defined(SQLITE_WIN32_HAS_ANSI) && SQLITE_WIN32_CREATEFILEMAPPINGA
      hMap = osCreateFileMappingA(pShmNode->hFile.h,
          NULL, protect, 0, nByte, NULL
      );
#endif
      OSTRACE(("SHM-MAP-CREATE pid=%lu, region=%d, size=%d, rc=%s\n",
               osGetCurrentProcessId(), pShmNode->nRegion, nByte,
               hMap ? "ok" : "failed"));
      if( hMap ){
        int iOffset = pShmNode->nRegion*szRegion;
        int iOffsetShift = iOffset % winSysInfo.dwAllocationGranularity;
#if SQLITE_OS_WINRT
        pMap = osMapViewOfFileFromApp(hMap, flags,
            iOffset - iOffsetShift, szRegion + iOffsetShift
        );
#else
        pMap = osMapViewOfFile(hMap, flags,
            0, iOffset - iOffsetShift, szRegion + iOffsetShift
        );
#endif
        OSTRACE(("SHM-MAP-MAP pid=%lu, region=%d, offset=%d, size=%d, rc=%s\n",
                 osGetCurrentProcessId(), pShmNode->nRegion, iOffset,
                 szRegion, pMap ? "ok" : "failed"));
      }
................................................................................
    int iOffset = iRegion*szRegion;
    int iOffsetShift = iOffset % winSysInfo.dwAllocationGranularity;
    char *p = (char *)pShmNode->aRegion[iRegion].pMap;
    *pp = (void *)&p[iOffsetShift];
  }else{
    *pp = 0;
  }
  if( pShmNode->isReadonly && rc==SQLITE_OK ) rc = SQLITE_READONLY;
  sqlite3_mutex_leave(pShmNode->mutex);
  return rc;
}

#else
# define winShmMap     0
# define winShmLock    0

set testdir [file dirname $argv0]
source $testdir/tester.tcl
source $testdir/lock_common.tcl
source $testdir/wal_common.tcl
set ::testprefix walro2

# These tests are only going to work on unix.
#
if {$::tcl_platform(platform) != "unix"} {
  finish_test
  return
}

# And only if the build is WAL-capable.
#
ifcapable !wal {
  finish_test
  return
}

set testdir [file dirname $argv0]
source $testdir/tester.tcl
source $testdir/lock_common.tcl
source $testdir/wal_common.tcl
set ::testprefix walro2








# And only if the build is WAL-capable.
#
ifcapable !wal {
  finish_test
  return
}

#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
source $testdir/malloc_common.tcl
set ::testprefix walro2

# These tests are only going to work on unix.
#
if {$::tcl_platform(platform) != "unix"} {
  finish_test
  return
}

# And only if the build is WAL-capable.
#
ifcapable !wal {
  finish_test
  return
}

#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
source $testdir/malloc_common.tcl
set ::testprefix walro2








# And only if the build is WAL-capable.
#
ifcapable !wal {
  finish_test
  return
}