os_win.c

sqlite-3.4.1,嵌入式数据库.是一个功能强大的开源数据库,给学习和研发以及小型公司的发展带来了全所未有的好处.

/*
** 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"

/*
** Determine if we are dealing with WindowsCE - which has a much
** reduced API.
*/
#if defined(_WIN32_WCE)
# define OS_WINCE 1
# define AreFileApisANSI() 1
#else
# define OS_WINCE 0
#endif

/*
** WinCE lacks native support for file locking so we have to fake it
** with some code of our own.
*/
#if 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 OsFile specific to the win32
** portability layer.
*/
typedef struct winFile winFile;
struct winFile {
  IoMethod const *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 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
};


/*
** 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

/*
** 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.
*/
int sqlite3_os_type = 0;

/*
** 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 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 /* OS_WINCE */

/*
** Convert a UTF-8 string to microsoft unicode (UTF-16?). 
**
** Space to hold the returned string is obtained from sqliteMalloc.
*/
static WCHAR *utf8ToUnicode(const char *zFilename){
  int nChar;
  WCHAR *zWideFilename;

  nChar = MultiByteToWideChar(CP_UTF8, 0, zFilename, -1, NULL, 0);
  zWideFilename = sqliteMalloc( nChar*sizeof(zWideFilename[0]) );
  if( zWideFilename==0 ){
    return 0;
  }
  nChar = MultiByteToWideChar(CP_UTF8, 0, zFilename, -1, zWideFilename, nChar);
  if( nChar==0 ){
    sqliteFree(zWideFilename);
    zWideFilename = 0;
  }
  return zWideFilename;
}

/*
** Convert microsoft unicode to UTF-8.  Space to hold the returned string is
** obtained from sqliteMalloc().
*/
static char *unicodeToUtf8(const WCHAR *zWideFilename){
  int nByte;
  char *zFilename;

  nByte = WideCharToMultiByte(CP_UTF8, 0, zWideFilename, -1, 0, 0, 0, 0);
  zFilename = sqliteMalloc( nByte );
  if( zFilename==0 ){
    return 0;
  }
  nByte = WideCharToMultiByte(CP_UTF8, 0, zWideFilename, -1, zFilename, nByte,
                              0, 0);
  if( nByte == 0 ){
    sqliteFree(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 sqliteMalloc.
*/
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 = sqliteMalloc( nByte*sizeof(zMbcsFilename[0]) );
  if( zMbcsFilename==0 ){
    return 0;
  }
  nByte = MultiByteToWideChar(codepage, 0, zFilename, -1, zMbcsFilename, nByte);
  if( nByte==0 ){
    sqliteFree(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
** sqliteMalloc().
*/
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 = sqliteMalloc( nByte );
  if( zFilename==0 ){
    return 0;
  }
  nByte = WideCharToMultiByte(codepage, 0, zWideFilename, -1, zFilename, nByte,
                              0, 0);
  if( nByte == 0 ){
    sqliteFree(zFilename);
    zFilename = 0;
  }
  return zFilename;
}

/*
** Convert multibyte character string to UTF-8.  Space to hold the
** returned string is obtained from sqliteMalloc().
*/
static char *mbcsToUtf8(const char *zFilename){
  char *zFilenameUtf8;
  WCHAR *zTmpWide;

  zTmpWide = mbcsToUnicode(zFilename);
  if( zTmpWide==0 ){
    return 0;
  }
  zFilenameUtf8 = unicodeToUtf8(zTmpWide);
  sqliteFree(zTmpWide);
  return zFilenameUtf8;
}

/*
** Convert UTF-8 to multibyte character string.  Space to hold the 
** returned string is obtained from sqliteMalloc().
*/
static char *utf8ToMbcs(const char *zFilename){
  char *zFilenameMbcs;
  WCHAR *zTmpWide;

  zTmpWide = utf8ToUnicode(zFilename);
  if( zTmpWide==0 ){
    return 0;
  }
  zFilenameMbcs = unicodeToMbcs(zTmpWide);
  sqliteFree(zTmpWide);
  return zFilenameMbcs;
}

#if 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;
  i64 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){
    sqliteFree(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;
  }

  sqliteFree(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);

    if( pFile->zDeleteOnClose ){
      DeleteFileW(pFile->zDeleteOnClose);
      sqliteFree(pFile->zDeleteOnClose);
      pFile->zDeleteOnClose = 0;
    }

    /* 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? */