/*

** 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.

**

** $Id: os_win.c,v 1.132 2008/07/31 01:34:34 shane Exp $

*/

#include "sqliteInt.h"

#if SQLITE_OS_WIN               /* This file is used for windows only */

/*

** A Note About Memory Allocation:

**

** This driver uses malloc()/free() directly rather than going through

** the SQLite-wrappers sqlite3_malloc()/sqlite3_free().  Those wrappers

** are designed for use on embedded systems where memory is scarce and

** malloc failures happen frequently.  Win32 does not typically run on

** embedded systems, and when it does the developers normally have bigger

** problems to worry about than running out of memory.  So there is not

** a compelling need to use the wrappers.

**

** But there is a good reason to not use the wrappers.  If we use the

** wrappers then we will get simulated malloc() failures within this

** driver.  And that causes all kinds of problems for our tests.  We

** could enhance SQLite to deal with simulated malloc failures within

** the OS driver, but the code to deal with those failure would not

** be exercised on Linux (which does not need to malloc() in the driver)

** and so we would have difficulty writing coverage tests for that

** code.  Better to leave the code out, we think.

**

** The point of this discussion is as follows:  When creating a new

** OS layer for an embedded system, if you use this file as an example,

** avoid the use of malloc()/free().  Those routines work ok on windows

** desktops but not so well in embedded systems.

*/

#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"

/*

** Determine if we are dealing with WindowsCE - which has a much

** reduced API.

*/

#if defined(SQLITE_OS_WINCE)

# define AreFileApisANSI() 1

#endif

/*

** WinCE lacks native support for file locking so we have to fake it

** with some code of our own.

*/

#if SQLITE_OS_WINCE

typedef struct winceLock {

  int nReaders;       /* Number of reader locks obtained */

  BOOL bPending;      /* Indicates a pending lock has been obtained */

  BOOL bReserved;     /* Indicates a reserved lock has been obtained */

  BOOL bExclusive;    /* Indicates an exclusive lock has been obtained */

} winceLock;

#endif

/*

** The winFile structure is a subclass of sqlite3_file* specific to the win32

** portability layer.

*/

typedef struct winFile winFile;

struct winFile {

  const sqlite3_io_methods *pMethod;/* Must be first */

  HANDLE h;               /* Handle for accessing the file */

  unsigned char locktype; /* Type of lock currently held on this file */

  short sharedLockByte;   /* Randomly chosen byte used as a shared lock */

#if SQLITE_OS_WINCE

  WCHAR *zDeleteOnClose;  /* Name of file to delete when closing */

  HANDLE hMutex;          /* Mutex used to control access to shared lock */  

  HANDLE hShared;         /* Shared memory segment used for locking */

  winceLock local;        /* Locks obtained by this instance of winFile */

  winceLock *shared;      /* Global shared lock memory for the file  */

#endif

};

/*

** The following variable is (normally) set once and never changes

** thereafter.  It records whether the operating system is Win95

** or WinNT.

**

** 0:   Operating system unknown.

** 1:   Operating system is Win95.

** 2:   Operating system is WinNT.

**

** In order to facilitate testing on a WinNT system, the test fixture

** can manually set this value to 1 to emulate Win98 behavior.

*/

#ifdef SQLITE_TEST

int sqlite3_os_type = 0;

#else

static int sqlite3_os_type = 0;

#endif

/*

** Return true (non-zero) if we are running under WinNT, Win2K, WinXP,

** or WinCE.  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.

*/

#if SQLITE_OS_WINCE

# define isNT()  (1)

#else

  static int isNT(void){

    if( sqlite3_os_type==0 ){

      OSVERSIONINFO sInfo;

      sInfo.dwOSVersionInfoSize = sizeof(sInfo);

      GetVersionEx(&sInfo);

      sqlite3_os_type = sInfo.dwPlatformId==VER_PLATFORM_WIN32_NT ? 2 : 1;

    }

    return sqlite3_os_type==2;

  }

#endif /* SQLITE_OS_WINCE */

/*

** Convert a UTF-8 string to microsoft unicode (UTF-16?). 

**

** Space to hold the returned string is obtained from malloc.

*/

static WCHAR *utf8ToUnicode(const char *zFilename){

  int nChar;

  WCHAR *zWideFilename;

  nChar = MultiByteToWideChar(CP_UTF8, 0, zFilename, -1, NULL, 0);

  zWideFilename = malloc( nChar*sizeof(zWideFilename[0]) );

  if( zWideFilename==0 ){

    return 0;

  }

  nChar = MultiByteToWideChar(CP_UTF8, 0, zFilename, -1, zWideFilename, nChar);

  if( nChar==0 ){

    free(zWideFilename);

    zWideFilename = 0;

  }

  return zWideFilename;

}

/*

** Convert microsoft unicode to UTF-8.  Space to hold the returned string is

** obtained from malloc().

*/

static char *unicodeToUtf8(const WCHAR *zWideFilename){

  int nByte;

  char *zFilename;

  nByte = WideCharToMultiByte(CP_UTF8, 0, zWideFilename, -1, 0, 0, 0, 0);

  zFilename = malloc( nByte );

  if( zFilename==0 ){

    return 0;

  }

  nByte = WideCharToMultiByte(CP_UTF8, 0, zWideFilename, -1, zFilename, nByte,

                              0, 0);

  if( nByte == 0 ){

    free(zFilename);

    zFilename = 0;

  }

  return zFilename;

}

/*

** Convert an ansi string to microsoft unicode, based on the

** current codepage settings for file apis.

** 

** Space to hold the returned string is obtained

** from malloc.

*/

static WCHAR *mbcsToUnicode(const char *zFilename){

  int nByte;

  WCHAR *zMbcsFilename;

  int codepage = AreFileApisANSI() ? CP_ACP : CP_OEMCP;

  nByte = MultiByteToWideChar(codepage, 0, zFilename, -1, NULL,0)*sizeof(WCHAR);

  zMbcsFilename = malloc( nByte*sizeof(zMbcsFilename[0]) );

  if( zMbcsFilename==0 ){

    return 0;

  }

  nByte = MultiByteToWideChar(codepage, 0, zFilename, -1, zMbcsFilename, nByte);

  if( nByte==0 ){

    free(zMbcsFilename);

    zMbcsFilename = 0;

  }

  return zMbcsFilename;

}

/*

** Convert microsoft unicode to multibyte character string, based on the

** user's Ansi codepage.

**

** Space to hold the returned string is obtained from

** malloc().

*/

static char *unicodeToMbcs(const WCHAR *zWideFilename){

  int nByte;

  char *zFilename;

  int codepage = AreFileApisANSI() ? CP_ACP : CP_OEMCP;

  nByte = WideCharToMultiByte(codepage, 0, zWideFilename, -1, 0, 0, 0, 0);

  zFilename = malloc( nByte );

  if( zFilename==0 ){

    return 0;

  }

  nByte = WideCharToMultiByte(codepage, 0, zWideFilename, -1, zFilename, nByte,

                              0, 0);

  if( nByte == 0 ){

    free(zFilename);

    zFilename = 0;

  }

  return zFilename;

}

/*

** Convert multibyte character string to UTF-8.  Space to hold the

** returned string is obtained from malloc().

*/

static char *mbcsToUtf8(const char *zFilename){

  char *zFilenameUtf8;

  WCHAR *zTmpWide;

  zTmpWide = mbcsToUnicode(zFilename);

  if( zTmpWide==0 ){

    return 0;

  }

  zFilenameUtf8 = unicodeToUtf8(zTmpWide);

  free(zTmpWide);

  return zFilenameUtf8;

}

/*

** Convert UTF-8 to multibyte character string.  Space to hold the 

** returned string is obtained from malloc().

*/

static char *utf8ToMbcs(const char *zFilename){

  char *zFilenameMbcs;

  WCHAR *zTmpWide;

  zTmpWide = utf8ToUnicode(zFilename);

  if( zTmpWide==0 ){

    return 0;

  }

  zFilenameMbcs = unicodeToMbcs(zTmpWide);

  free(zTmpWide);

  return zFilenameMbcs;

}

#if SQLITE_OS_WINCE

/*************************************************************************

** This section contains code for WinCE only.

*/

/*

** WindowsCE does not have a localtime() function.  So create a

** substitute.

*/

#include <time.h>

struct tm *__cdecl localtime(const time_t *t)

{

  static struct tm y;

  FILETIME uTm, lTm;

  SYSTEMTIME pTm;

  sqlite3_int64 t64;

  t64 = *t;

  t64 = (t64 + 11644473600)*10000000;

  uTm.dwLowDateTime = t64 & 0xFFFFFFFF;

  uTm.dwHighDateTime= t64 >> 32;

  FileTimeToLocalFileTime(&uTm,&lTm);

  FileTimeToSystemTime(&lTm,&pTm);

  y.tm_year = pTm.wYear - 1900;

  y.tm_mon = pTm.wMonth - 1;

  y.tm_wday = pTm.wDayOfWeek;

  y.tm_mday = pTm.wDay;

  y.tm_hour = pTm.wHour;

  y.tm_min = pTm.wMinute;

  y.tm_sec = pTm.wSecond;

  return &y;

}

/* This will never be called, but defined to make the code compile */

#define GetTempPathA(a,b)

#define LockFile(a,b,c,d,e)       winceLockFile(&a, b, c, d, e)

#define UnlockFile(a,b,c,d,e)     winceUnlockFile(&a, b, c, d, e)

#define LockFileEx(a,b,c,d,e,f)   winceLockFileEx(&a, b, c, d, e, f)

#define HANDLE_TO_WINFILE(a) (winFile*)&((char*)a)[-offsetof(winFile,h)]

/*

** Acquire a lock on the handle h

*/

static void winceMutexAcquire(HANDLE h){

   DWORD dwErr;

   do {

     dwErr = WaitForSingleObject(h, INFINITE);

   } while (dwErr != WAIT_OBJECT_0 && dwErr != WAIT_ABANDONED);

}

/*

** Release a lock acquired by winceMutexAcquire()

*/

#define winceMutexRelease(h) ReleaseMutex(h)

/*

** Create the mutex and shared memory used for locking in the file

** descriptor pFile

*/

static BOOL winceCreateLock(const char *zFilename, winFile *pFile){

  WCHAR *zTok;

  WCHAR *zName = utf8ToUnicode(zFilename);

  BOOL bInit = TRUE;

  /* Initialize the local lockdata */

  ZeroMemory(&pFile->local, sizeof(pFile->local));

  /* Replace the backslashes from the filename and lowercase it

  ** to derive a mutex name. */

  zTok = CharLowerW(zName);

  for (;*zTok;zTok++){

    if (*zTok == '\\') *zTok = '_';

  }

  /* Create/open the named mutex */

  pFile->hMutex = CreateMutexW(NULL, FALSE, zName);

  if (!pFile->hMutex){

    free(zName);

    return FALSE;

  }

  /* Acquire the mutex before continuing */

  winceMutexAcquire(pFile->hMutex);

  /* Since the names of named mutexes, semaphores, file mappings etc are 

  ** case-sensitive, take advantage of that by uppercasing the mutex name

  ** and using that as the shared filemapping name.

  */

  CharUpperW(zName);

  pFile->hShared = CreateFileMappingW(INVALID_HANDLE_VALUE, NULL,

                                       PAGE_READWRITE, 0, sizeof(winceLock),

                                       zName);  

  /* Set a flag that indicates we're the first to create the memory so it 

  ** must be zero-initialized */

  if (GetLastError() == ERROR_ALREADY_EXISTS){

    bInit = FALSE;

  }

  free(zName);

  /* If we succeeded in making the shared memory handle, map it. */

  if (pFile->hShared){

    pFile->shared = (winceLock*)MapViewOfFile(pFile->hShared, 

             FILE_MAP_READ|FILE_MAP_WRITE, 0, 0, sizeof(winceLock));

    /* If mapping failed, close the shared memory handle and erase it */

    if (!pFile->shared){

      CloseHandle(pFile->hShared);

      pFile->hShared = NULL;

    }

  }

  /* If shared memory could not be created, then close the mutex and fail */

  if (pFile->hShared == NULL){

    winceMutexRelease(pFile->hMutex);

    CloseHandle(pFile->hMutex);

    pFile->hMutex = NULL;

    return FALSE;

  }

  /* Initialize the shared memory if we're supposed to */

  if (bInit) {

    ZeroMemory(pFile->shared, sizeof(winceLock));

  }

  winceMutexRelease(pFile->hMutex);

  return TRUE;

}

/*

** Destroy the part of winFile that deals with wince locks

*/

static void winceDestroyLock(winFile *pFile){

  if (pFile->hMutex){

    /* Acquire the mutex */

    winceMutexAcquire(pFile->hMutex);

    /* The following blocks should probably assert in debug mode, but they

       are to cleanup in case any locks remained open */

    if (pFile->local.nReaders){

      pFile->shared->nReaders --;

    }

    if (pFile->local.bReserved){

      pFile->shared->bReserved = FALSE;

    }

    if (pFile->local.bPending){

      pFile->shared->bPending = FALSE;

    }

    if (pFile->local.bExclusive){

      pFile->shared->bExclusive = FALSE;

    }

    /* De-reference and close our copy of the shared memory handle */

    UnmapViewOfFile(pFile->shared);

    CloseHandle(pFile->hShared);

    /* Done with the mutex */

    winceMutexRelease(pFile->hMutex);    

    CloseHandle(pFile->hMutex);

    pFile->hMutex = NULL;

  }

}

/* 

** An implementation of the LockFile() API of windows for wince

*/

static BOOL winceLockFile(

  HANDLE *phFile,

  DWORD dwFileOffsetLow,

  DWORD dwFileOffsetHigh,

  DWORD nNumberOfBytesToLockLow,

  DWORD nNumberOfBytesToLockHigh

){

  winFile *pFile = HANDLE_TO_WINFILE(phFile);

  BOOL bReturn = FALSE;

  if (!pFile->hMutex) return TRUE;

  winceMutexAcquire(pFile->hMutex);

  /* Wanting an exclusive lock? */

  if (dwFileOffsetLow == SHARED_FIRST

       && nNumberOfBytesToLockLow == SHARED_SIZE){

    if (pFile->shared->nReaders == 0 && pFile->shared->bExclusive == 0){

       pFile->shared->bExclusive = TRUE;

       pFile->local.bExclusive = TRUE;

       bReturn = TRUE;

    }

  }

  /* Want a read-only lock? */

  else if ((dwFileOffsetLow >= SHARED_FIRST &&

            dwFileOffsetLow < SHARED_FIRST + SHARED_SIZE) &&

            nNumberOfBytesToLockLow == 1){

    if (pFile->shared->bExclusive == 0){

      pFile->local.nReaders ++;

      if (pFile->local.nReaders == 1){

        pFile->shared->nReaders ++;

      }

      bReturn = TRUE;

    }

  }

  /* Want a pending lock? */

  else if (dwFileOffsetLow == PENDING_BYTE && nNumberOfBytesToLockLow == 1){

    /* If no pending lock has been acquired, then acquire it */

    if (pFile->shared->bPending == 0) {

      pFile->shared->bPending = TRUE;

      pFile->local.bPending = TRUE;

      bReturn = TRUE;

    }

  }

  /* Want a reserved lock? */

  else if (dwFileOffsetLow == RESERVED_BYTE && nNumberOfBytesToLockLow == 1){

    if (pFile->shared->bReserved == 0) {

      pFile->shared->bReserved = TRUE;

      pFile->local.bReserved = TRUE;

      bReturn = TRUE;

    }

  }

  winceMutexRelease(pFile->hMutex);

  return bReturn;

}

/*

** An implementation of the UnlockFile API of windows for wince

*/

static BOOL winceUnlockFile(

  HANDLE *phFile,

  DWORD dwFileOffsetLow,

  DWORD dwFileOffsetHigh,

  DWORD nNumberOfBytesToUnlockLow,

  DWORD nNumberOfBytesToUnlockHigh

){

  winFile *pFile = HANDLE_TO_WINFILE(phFile);

  BOOL bReturn = FALSE;

  if (!pFile->hMutex) return TRUE;

  winceMutexAcquire(pFile->hMutex);

  /* Releasing a reader lock or an exclusive lock */

  if (dwFileOffsetLow >= SHARED_FIRST &&

       dwFileOffsetLow < SHARED_FIRST + SHARED_SIZE){

    /* Did we have an exclusive lock? */

    if (pFile->local.bExclusive){

      pFile->local.bExclusive = FALSE;

      pFile->shared->bExclusive = FALSE;

      bReturn = TRUE;

    }

    /* Did we just have a reader lock? */

    else if (pFile->local.nReaders){