Initial commit

Signed-off-by: Mavridis Philippe <mavridisf@gmail.com>

1 files changed, 767 insertions, 0 deletions

diff --git a/src/sqlite/os_win.c b/src/sqlite/os_win.c
new file mode 100644
index 0000000..ea2ca26
--- /dev/null
+++ b/src/sqlite/os_win.c
@@ -0,0 +1,767 @@
+/*
+** 2004 May 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains code that is specific to windows.
+*/
+#include "sqliteInt.h"
+#include "os.h"
+#if OS_WIN               /* This file is used for windows only */
+
+#include <winbase.h>
+
+#ifdef __CYGWIN__
+# include <sys/cygwin.h>
+#endif
+
+/*
+** Macros used to determine whether or not to use threads.
+*/
+#if defined(THREADSAFE) && THREADSAFE
+# define SQLITE_W32_THREADS 1
+#endif
+
+/*
+** Include code that is common to all os_*.c files
+*/
+#include "os_common.h"
+
+/*
+** Do not include any of the File I/O interface procedures if the
+** SQLITE_OMIT_DISKIO macro is defined (indicating that there database
+** will be in-memory only)
+*/
+#ifndef SQLITE_OMIT_DISKIO
+
+/*
+** Delete the named file
+*/
+int sqlite3OsDelete(const char *zFilename){
+  DeleteFileA(zFilename);
+  TRACE2("DELETE \"%s\"\n", zFilename);
+  return SQLITE_OK;
+}
+
+/*
+** Return TRUE if the named file exists.
+*/
+int sqlite3OsFileExists(const char *zFilename){
+  return GetFileAttributesA(zFilename) != 0xffffffff;
+}
+
+/*
+** Attempt to open a file for both reading and writing.  If that
+** fails, try opening it read-only.  If the file does not exist,
+** try to create it.
+**
+** On success, a handle for the open file is written to *id
+** and *pReadonly is set to 0 if the file was opened for reading and
+** writing or 1 if the file was opened read-only.  The function returns
+** SQLITE_OK.
+**
+** On failure, the function returns SQLITE_CANTOPEN and leaves
+** *id and *pReadonly unchanged.
+*/
+int sqlite3OsOpenReadWrite(
+  const char *zFilename,
+  OsFile *id,
+  int *pReadonly
+){
+  HANDLE h;
+  assert( !id->isOpen );
+  h = CreateFileA(zFilename,
+     GENERIC_READ | GENERIC_WRITE,
+     FILE_SHARE_READ | FILE_SHARE_WRITE,
+     NULL,
+     OPEN_ALWAYS,
+     FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
+     NULL
+  );
+  if( h==INVALID_HANDLE_VALUE ){
+    h = CreateFileA(zFilename,
+       GENERIC_READ,
+       FILE_SHARE_READ,
+       NULL,
+       OPEN_ALWAYS,
+       FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
+       NULL
+    );
+    if( h==INVALID_HANDLE_VALUE ){
+      return SQLITE_CANTOPEN;
+    }
+    *pReadonly = 1;
+  }else{
+    *pReadonly = 0;
+  }
+  id->h = h;
+  id->locktype = NO_LOCK;
+  id->sharedLockByte = 0;
+  id->isOpen = 1;
+  OpenCounter(+1);
+  TRACE3("OPEN R/W %d \"%s\"\n", h, zFilename);
+  return SQLITE_OK;
+}
+
+
+/*
+** Attempt to open a new file for exclusive access by this process.
+** The file will be opened for both reading and writing.  To avoid
+** a potential security problem, we do not allow the file to have
+** previously existed.  Nor do we allow the file to be a symbolic
+** link.
+**
+** If delFlag is true, then make arrangements to automatically delete
+** the file when it is closed.
+**
+** On success, write the file handle into *id and return SQLITE_OK.
+**
+** On failure, return SQLITE_CANTOPEN.
+*/
+int sqlite3OsOpenExclusive(const char *zFilename, OsFile *id, int delFlag){
+  HANDLE h;
+  int fileflags;
+  assert( !id->isOpen );
+  if( delFlag ){
+    fileflags = FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_RANDOM_ACCESS 
+                     | FILE_FLAG_DELETE_ON_CLOSE;
+  }else{
+    fileflags = FILE_FLAG_RANDOM_ACCESS;
+  }
+  h = CreateFileA(zFilename,
+     GENERIC_READ | GENERIC_WRITE,
+     0,
+     NULL,
+     CREATE_ALWAYS,
+     fileflags,
+     NULL
+  );
+  if( h==INVALID_HANDLE_VALUE ){
+    return SQLITE_CANTOPEN;
+  }
+  id->h = h;
+  id->locktype = NO_LOCK;
+  id->sharedLockByte = 0;
+  id->isOpen = 1;
+  OpenCounter(+1);
+  TRACE3("OPEN EX %d \"%s\"\n", h, zFilename);
+  return SQLITE_OK;
+}
+
+/*
+** Attempt to open a new file for read-only access.
+**
+** On success, write the file handle into *id and return SQLITE_OK.
+**
+** On failure, return SQLITE_CANTOPEN.
+*/
+int sqlite3OsOpenReadOnly(const char *zFilename, OsFile *id){
+  HANDLE h;
+  assert( !id->isOpen );
+  h = CreateFileA(zFilename,
+     GENERIC_READ,
+     0,
+     NULL,
+     OPEN_EXISTING,
+     FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
+     NULL
+  );
+  if( h==INVALID_HANDLE_VALUE ){
+    return SQLITE_CANTOPEN;
+  }
+  id->h = h;
+  id->locktype = NO_LOCK;
+  id->sharedLockByte = 0;
+  id->isOpen = 1;
+  OpenCounter(+1);
+  TRACE3("OPEN RO %d \"%s\"\n", h, zFilename);
+  return SQLITE_OK;
+}
+
+/*
+** Attempt to open a file descriptor for the directory that contains a
+** file.  This file descriptor can be used to fsync() the directory
+** in order to make sure the creation of a new file is actually written
+** to disk.
+**
+** This routine is only meaningful for Unix.  It is a no-op under
+** windows since windows does not support hard links.
+**
+** On success, a handle for a previously open file is at *id is
+** updated with the new directory file descriptor and SQLITE_OK is
+** returned.
+**
+** On failure, the function returns SQLITE_CANTOPEN and leaves
+** *id unchanged.
+*/
+int sqlite3OsOpenDirectory(
+  const char *zDirname,
+  OsFile *id
+){
+  return SQLITE_OK;
+}
+
+/*
+** If the following global variable points to a string which is the
+** name of a directory, then that directory will be used to store
+** temporary files.
+*/
+char *sqlite3_temp_directory = 0;
+
+/*
+** Create a temporary file name in zBuf.  zBuf must be big enough to
+** hold at least SQLITE_TEMPNAME_SIZE characters.
+*/
+int sqlite3OsTempFileName(char *zBuf){
+  static char zChars[] =
+    "abcdefghijklmnopqrstuvwxyz"
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+    "0123456789";
+  int i, j;
+  char zTempPath[SQLITE_TEMPNAME_SIZE];
+  if( sqlite3_temp_directory ){
+    strncpy(zTempPath, sqlite3_temp_directory, SQLITE_TEMPNAME_SIZE-30);
+    zTempPath[SQLITE_TEMPNAME_SIZE-30] = 0;
+  }else{
+    GetTempPathA(SQLITE_TEMPNAME_SIZE-30, zTempPath);
+  }
+  for(i=strlen(zTempPath); i>0 && zTempPath[i-1]=='\\'; i--){}
+  zTempPath[i] = 0;
+  for(;;){
+    sprintf(zBuf, "%s\\"TEMP_FILE_PREFIX, zTempPath);
+    j = strlen(zBuf);
+    sqlite3Randomness(15, &zBuf[j]);
+    for(i=0; i<15; i++, j++){
+      zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
+    }
+    zBuf[j] = 0;
+    if( !sqlite3OsFileExists(zBuf) ) break;
+  }
+  TRACE2("TEMP FILENAME: %s\n", zBuf);
+  return SQLITE_OK; 
+}
+
+/*
+** Close a file.
+*/
+int sqlite3OsClose(OsFile *id){
+  if( id->isOpen ){
+    TRACE2("CLOSE %d\n", id->h);
+    CloseHandle(id->h);
+    OpenCounter(-1);
+    id->isOpen = 0;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Read data from a file into a buffer.  Return SQLITE_OK if all
+** bytes were read successfully and SQLITE_IOERR if anything goes
+** wrong.
+*/
+int sqlite3OsRead(OsFile *id, void *pBuf, int amt){
+  DWORD got;
+  assert( id->isOpen );
+  SimulateIOError(SQLITE_IOERR);
+  TRACE3("READ %d lock=%d\n", id->h, id->locktype);
+  if( !ReadFile(id->h, pBuf, amt, &got, 0) ){
+    got = 0;
+  }
+  if( got==(DWORD)amt ){
+    return SQLITE_OK;
+  }else{
+    return SQLITE_IOERR;
+  }
+}
+
+/*
+** Write data from a buffer into a file.  Return SQLITE_OK on success
+** or some other error code on failure.
+*/
+int sqlite3OsWrite(OsFile *id, const void *pBuf, int amt){
+  int rc = 0;
+  DWORD wrote;
+  assert( id->isOpen );
+  SimulateIOError(SQLITE_IOERR);
+  SimulateDiskfullError;
+  TRACE3("WRITE %d lock=%d\n", id->h, id->locktype);
+  assert( amt>0 );
+  while( amt>0 && (rc = WriteFile(id->h, pBuf, amt, &wrote, 0))!=0 && wrote>0 ){
+    amt -= wrote;
+    pBuf = &((char*)pBuf)[wrote];
+  }
+  if( !rc || amt>(int)wrote ){
+    return SQLITE_FULL;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Move the read/write pointer in a file.
+*/
+int sqlite3OsSeek(OsFile *id, i64 offset){
+  LONG upperBits = offset>>32;
+  LONG lowerBits = offset & 0xffffffff;
+  DWORD rc;
+  assert( id->isOpen );
+  SEEK(offset/1024 + 1);
+  rc = SetFilePointer(id->h, lowerBits, &upperBits, FILE_BEGIN);
+  TRACE3("SEEK %d %lld\n", id->h, offset);
+  return SQLITE_OK;
+}
+
+/*
+** Make sure all writes to a particular file are committed to disk.
+*/
+int sqlite3OsSync(OsFile *id){
+  assert( id->isOpen );
+  TRACE3("SYNC %d lock=%d\n", id->h, id->locktype);
+  if( FlushFileBuffers(id->h) ){
+    return SQLITE_OK;
+  }else{
+    return SQLITE_IOERR;
+  }
+}
+
+/*
+** Sync the directory zDirname. This is a no-op on operating systems other
+** than UNIX.
+*/
+int sqlite3OsSyncDirectory(const char *zDirname){
+  SimulateIOError(SQLITE_IOERR);
+  return SQLITE_OK;
+}
+
+/*
+** Truncate an open file to a specified size
+*/
+int sqlite3OsTruncate(OsFile *id, i64 nByte){
+  LONG upperBits = nByte>>32;
+  assert( id->isOpen );
+  TRACE3("TRUNCATE %d %lld\n", id->h, nByte);
+  SimulateIOError(SQLITE_IOERR);
+  SetFilePointer(id->h, nByte, &upperBits, FILE_BEGIN);
+  SetEndOfFile(id->h);
+  return SQLITE_OK;
+}
+
+/*
+** Determine the current size of a file in bytes
+*/
+int sqlite3OsFileSize(OsFile *id, i64 *pSize){
+  DWORD upperBits, lowerBits;
+  assert( id->isOpen );
+  SimulateIOError(SQLITE_IOERR);
+  lowerBits = GetFileSize(id->h, &upperBits);
+  *pSize = (((i64)upperBits)<<32) + lowerBits;
+  return SQLITE_OK;
+}
+
+/*
+** Return true (non-zero) if we are running under WinNT, Win2K or WinXP.
+** Return false (zero) for Win95, Win98, or WinME.
+**
+** Here is an interesting observation:  Win95, Win98, and WinME lack
+** the LockFileEx() API.  But we can still statically link against that
+** API as long as we don't call it win running Win95/98/ME.  A call to
+** this routine is used to determine if the host is Win95/98/ME or
+** WinNT/2K/XP so that we will know whether or not we can safely call
+** the LockFileEx() API.
+*/
+static int isNT(void){
+  static int osType = 0;   /* 0=unknown 1=win95 2=winNT */
+  if( osType==0 ){
+    OSVERSIONINFO sInfo;
+    sInfo.dwOSVersionInfoSize = sizeof(sInfo);
+    GetVersionEx(&sInfo);
+    osType = sInfo.dwPlatformId==VER_PLATFORM_WIN32_NT ? 2 : 1;
+  }
+  return osType==2;
+}
+
+/*
+** Acquire a reader lock.
+** Different API routines are called depending on whether or not this
+** is Win95 or WinNT.
+*/
+static int getReadLock(OsFile *id){
+  int res;
+  if( isNT() ){
+    OVERLAPPED ovlp;
+    ovlp.Offset = SHARED_FIRST;
+    ovlp.OffsetHigh = 0;
+    ovlp.hEvent = 0;
+    res = LockFileEx(id->h, LOCKFILE_FAIL_IMMEDIATELY, 0, SHARED_SIZE,0,&ovlp);
+  }else{
+    int lk;
+    sqlite3Randomness(sizeof(lk), &lk);
+    id->sharedLockByte = (lk & 0x7fffffff)%(SHARED_SIZE - 1);
+    res = LockFile(id->h, SHARED_FIRST+id->sharedLockByte, 0, 1, 0);
+  }
+  return res;
+}
+
+/*
+** Undo a readlock
+*/
+static int unlockReadLock(OsFile *id){
+  int res;
+  if( isNT() ){
+    res = UnlockFile(id->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
+  }else{
+    res = UnlockFile(id->h, SHARED_FIRST + id->sharedLockByte, 0, 1, 0);
+  }
+  return res;
+}
+
+#ifndef SQLITE_OMIT_PAGER_PRAGMAS
+/*
+** Check that a given pathname is a directory and is writable 
+**
+*/
+int sqlite3OsIsDirWritable(char *zBuf){
+  int fileAttr;
+  if(! zBuf ) return 0;
+  if(! isNT() && strlen(zBuf) > MAX_PATH ) return 0;
+  fileAttr = GetFileAttributesA(zBuf);
+  if( fileAttr == 0xffffffff ) return 0;
+  if( (fileAttr & FILE_ATTRIBUTE_DIRECTORY) != FILE_ATTRIBUTE_DIRECTORY ){
+    return 0;
+  }
+  return 1;
+}
+#endif /* SQLITE_OMIT_PAGER_PRAGMAS */
+
+/*
+** Lock the file with the lock specified by parameter locktype - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** This routine will only increase a lock.  The sqlite3OsUnlock() routine
+** erases all locks at once and returns us immediately to locking level 0.
+** It is not possible to lower the locking level one step at a time.  You
+** must go straight to locking level 0.
+*/
+int sqlite3OsLock(OsFile *id, int locktype){
+  int rc = SQLITE_OK;    /* Return code from subroutines */
+  int res = 1;           /* Result of a windows lock call */
+  int newLocktype;       /* Set id->locktype to this value before exiting */
+  int gotPendingLock = 0;/* True if we acquired a PENDING lock this time */
+
+  assert( id->isOpen );
+  TRACE5("LOCK %d %d was %d(%d)\n",
+          id->h, locktype, id->locktype, id->sharedLockByte);
+
+  /* If there is already a lock of this type or more restrictive on the
+  ** OsFile, do nothing. Don't use the end_lock: exit path, as
+  ** sqlite3OsEnterMutex() hasn't been called yet.
+  */
+  if( id->locktype>=locktype ){
+    return SQLITE_OK;
+  }
+
+  /* Make sure the locking sequence is correct
+  */
+  assert( id->locktype!=NO_LOCK || locktype==SHARED_LOCK );
+  assert( locktype!=PENDING_LOCK );
+  assert( locktype!=RESERVED_LOCK || id->locktype==SHARED_LOCK );
+
+  /* Lock the PENDING_LOCK byte if we need to acquire a PENDING lock or
+  ** a SHARED lock.  If we are acquiring a SHARED lock, the acquisition of
+  ** the PENDING_LOCK byte is temporary.
+  */
+  newLocktype = id->locktype;
+  if( id->locktype==NO_LOCK
+   || (locktype==EXCLUSIVE_LOCK && id->locktype==RESERVED_LOCK)
+  ){
+    int cnt = 3;
+    while( cnt-->0 && (res = LockFile(id->h, PENDING_BYTE, 0, 1, 0))==0 ){
+      /* Try 3 times to get the pending lock.  The pending lock might be
+      ** held by another reader process who will release it momentarily.
+      */
+      TRACE2("could not get a PENDING lock. cnt=%d\n", cnt);
+      Sleep(1);
+    }
+    gotPendingLock = res;
+  }
+
+  /* Acquire a shared lock
+  */
+  if( locktype==SHARED_LOCK && res ){
+    assert( id->locktype==NO_LOCK );
+    res = getReadLock(id);
+    if( res ){
+      newLocktype = SHARED_LOCK;
+    }
+  }
+
+  /* Acquire a RESERVED lock
+  */
+  if( locktype==RESERVED_LOCK && res ){
+    assert( id->locktype==SHARED_LOCK );
+    res = LockFile(id->h, RESERVED_BYTE, 0, 1, 0);
+    if( res ){
+      newLocktype = RESERVED_LOCK;
+    }
+  }
+
+  /* Acquire a PENDING lock
+  */
+  if( locktype==EXCLUSIVE_LOCK && res ){
+    newLocktype = PENDING_LOCK;
+    gotPendingLock = 0;
+  }
+
+  /* Acquire an EXCLUSIVE lock
+  */
+  if( locktype==EXCLUSIVE_LOCK && res ){
+    assert( id->locktype>=SHARED_LOCK );
+    res = unlockReadLock(id);
+    TRACE2("unreadlock = %d\n", res);
+    res = LockFile(id->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
+    if( res ){
+      newLocktype = EXCLUSIVE_LOCK;
+    }else{
+      TRACE2("error-code = %d\n", GetLastError());
+    }
+  }
+
+  /* If we are holding a PENDING lock that ought to be released, then
+  ** release it now.
+  */
+  if( gotPendingLock && locktype==SHARED_LOCK ){
+    UnlockFile(id->h, PENDING_BYTE, 0, 1, 0);
+  }
+
+  /* Update the state of the lock has held in the file descriptor then
+  ** return the appropriate result code.
+  */
+  if( res ){
+    rc = SQLITE_OK;
+  }else{
+    TRACE4("LOCK FAILED %d trying for %d but got %d\n", id->h,
+           locktype, newLocktype);
+    rc = SQLITE_BUSY;
+  }
+  id->locktype = newLocktype;
+  return rc;
+}
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, return
+** non-zero, otherwise zero.
+*/
+int sqlite3OsCheckReservedLock(OsFile *id){
+  int rc;
+  assert( id->isOpen );
+  if( id->locktype>=RESERVED_LOCK ){
+    rc = 1;
+    TRACE3("TEST WR-LOCK %d %d (local)\n", id->h, rc);
+  }else{
+    rc = LockFile(id->h, RESERVED_BYTE, 0, 1, 0);
+    if( rc ){
+      UnlockFile(id->h, RESERVED_BYTE, 0, 1, 0);
+    }
+    rc = !rc;
+    TRACE3("TEST WR-LOCK %d %d (remote)\n", id->h, rc);
+  }
+  return rc;
+}
+
+/*
+** Lower the locking level on file descriptor id to locktype.  locktype
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+**
+** It is not possible for this routine to fail if the second argument
+** is NO_LOCK.  If the second argument is SHARED_LOCK then this routine
+** might return SQLITE_IOERR;
+*/
+int sqlite3OsUnlock(OsFile *id, int locktype){
+  int type;
+  int rc = SQLITE_OK;
+  assert( id->isOpen );
+  assert( locktype<=SHARED_LOCK );
+  TRACE5("UNLOCK %d to %d was %d(%d)\n", id->h, locktype,
+          id->locktype, id->sharedLockByte);
+  type = id->locktype;
+  if( type>=EXCLUSIVE_LOCK ){
+    UnlockFile(id->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
+    if( locktype==SHARED_LOCK && !getReadLock(id) ){
+      /* This should never happen.  We should always be able to
+      ** reacquire the read lock */
+      rc = SQLITE_IOERR;
+    }
+  }
+  if( type>=RESERVED_LOCK ){
+    UnlockFile(id->h, RESERVED_BYTE, 0, 1, 0);
+  }
+  if( locktype==NO_LOCK && type>=SHARED_LOCK ){
+    unlockReadLock(id);
+  }
+  if( type>=PENDING_LOCK ){
+    UnlockFile(id->h, PENDING_BYTE, 0, 1, 0);
+  }
+  id->locktype = locktype;
+  return rc;
+}
+
+/*
+** Turn a relative pathname into a full pathname.  Return a pointer
+** to the full pathname stored in space obtained from sqliteMalloc().
+** The calling function is responsible for freeing this space once it
+** is no longer needed.
+*/
+char *sqlite3OsFullPathname(const char *zRelative){
+  char *zNotUsed;
+  char *zFull;
+  int nByte;
+#ifdef __CYGWIN__
+  nByte = strlen(zRelative) + MAX_PATH + 1001;
+  zFull = sqliteMalloc( nByte );
+  if( zFull==0 ) return 0;
+  if( cygwin_conv_to_full_win32_path(zRelative, zFull) ) return 0;
+#else
+  nByte = GetFullPathNameA(zRelative, 0, 0, &zNotUsed) + 1;
+  zFull = sqliteMalloc( nByte );
+  if( zFull==0 ) return 0;
+  GetFullPathNameA(zRelative, nByte, zFull, &zNotUsed);
+#endif
+  return zFull;
+}
+
+#endif /* SQLITE_OMIT_DISKIO */
+/***************************************************************************
+** Everything above deals with file I/O.  Everything that follows deals
+** with other miscellanous aspects of the operating system interface
+****************************************************************************/
+
+/*
+** Get information to seed the random number generator.  The seed
+** is written into the buffer zBuf[256].  The calling function must
+** supply a sufficiently large buffer.
+*/
+int sqlite3OsRandomSeed(char *zBuf){
+  /* We have to initialize zBuf to prevent valgrind from reporting
+  ** errors.  The reports issued by valgrind are incorrect - we would
+  ** prefer that the randomness be increased by making use of the
+  ** uninitialized space in zBuf - but valgrind errors tend to worry
+  ** some users.  Rather than argue, it seems easier just to initialize
+  ** the whole array and silence valgrind, even if that means less randomness
+  ** in the random seed.
+  **
+  ** When testing, initializing zBuf[] to zero is all we do.  That means
+  ** that we always use the same random number sequence.* This makes the
+  ** tests repeatable.
+  */
+  memset(zBuf, 0, 256);
+  GetSystemTime((LPSYSTEMTIME)zBuf);
+  return SQLITE_OK;
+}
+
+/*
+** Sleep for a little while.  Return the amount of time slept.
+*/
+int sqlite3OsSleep(int ms){
+  Sleep(ms);
+  return ms;
+}
+
+/*
+** Static variables used for thread synchronization
+*/
+static int inMutex = 0;
+#ifdef SQLITE_W32_THREADS
+  static CRITICAL_SECTION cs;
+#endif
+
+/*
+** The following pair of routine implement mutual exclusion for
+** multi-threaded processes.  Only a single thread is allowed to
+** executed code that is surrounded by EnterMutex() and LeaveMutex().
+**
+** SQLite uses only a single Mutex.  There is not much critical
+** code and what little there is executes quickly and without blocking.
+*/
+void sqlite3OsEnterMutex(){
+#ifdef SQLITE_W32_THREADS
+  static int isInit = 0;
+  while( !isInit ){
+    static long lock = 0;
+    if( InterlockedIncrement(&lock)==1 ){
+      InitializeCriticalSection(&cs);
+      isInit = 1;
+    }else{
+      Sleep(1);
+    }
+  }
+  EnterCriticalSection(&cs);
+#endif
+  assert( !inMutex );
+  inMutex = 1;
+}
+void sqlite3OsLeaveMutex(){
+  assert( inMutex );
+  inMutex = 0;
+#ifdef SQLITE_W32_THREADS
+  LeaveCriticalSection(&cs);
+#endif
+}
+
+/*
+** The following variable, if set to a non-zero value, becomes the result
+** returned from sqlite3OsCurrentTime().  This is used for testing.
+*/
+#ifdef SQLITE_TEST
+int sqlite3_current_time = 0;
+#endif
+
+/*
+** Find the current time (in Universal Coordinated Time).  Write the
+** current time and date as a Julian Day number into *prNow and
+** return 0.  Return 1 if the time and date cannot be found.
+*/
+int sqlite3OsCurrentTime(double *prNow){
+  FILETIME ft;
+  /* FILETIME structure is a 64-bit value representing the number of 
+     100-nanosecond intervals since January 1, 1601 (= JD 2305813.5). 
+  */
+  double now;
+  GetSystemTimeAsFileTime( &ft );
+  now = ((double)ft.dwHighDateTime) * 4294967296.0; 
+  *prNow = (now + ft.dwLowDateTime)/864000000000.0 + 2305813.5;
+#ifdef SQLITE_TEST
+  if( sqlite3_current_time ){
+    *prNow = sqlite3_current_time/86400.0 + 2440587.5;
+  }
+#endif
+  return 0;
+}
+
+#endif /* OS_WIN */