os.h

sqlite嵌入式数据库源码

/*
** 2001 September 16
**
** 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 header file (together with is companion C source-code file
** "os.c") attempt to abstract the underlying operating system so that
** the SQLite library will work on both POSIX and windows systems.
*/
#ifndef _SQLITE_OS_H_
#define _SQLITE_OS_H_

/*
** Figure out if we are dealing with Unix, Windows, or some other
** operating system.
*/
#if !defined(OS_UNIX) && !defined(OS_OTHER)
# define OS_OTHER 0
# ifndef OS_WIN
#   if defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) || defined(__MINGW32__) || defined(__BORLANDC__)
#     define OS_WIN 1
#     define OS_UNIX 0
#     define OS_OS2 0
#   elif defined(_EMX_) || defined(_OS2) || defined(OS2) || defined(_OS2_) || defined(__OS2__)
#     define OS_WIN 0
#     define OS_UNIX 0
#     define OS_OS2 1
#   else
#     define OS_WIN 0
#     define OS_UNIX 1
#     define OS_OS2 0
#  endif
# else
#  define OS_UNIX 0
#  define OS_OS2 0
# endif
#else
# ifndef OS_WIN
#  define OS_WIN 0
# endif
#endif


/*
** Define the maximum size of a temporary filename
*/
#if OS_WIN
# include <windows.h>
# define SQLITE_TEMPNAME_SIZE (MAX_PATH+50)
#elif OS_OS2
# define INCL_DOSDATETIME
# define INCL_DOSFILEMGR
# define INCL_DOSERRORS
# define INCL_DOSMISC
# define INCL_DOSPROCESS
# include <os2.h>
# define SQLITE_TEMPNAME_SIZE (CCHMAXPATHCOMP)
#else
# define SQLITE_TEMPNAME_SIZE 200
#endif

/* If the SET_FULLSYNC macro is not defined above, then make it
** a no-op
*/
#ifndef SET_FULLSYNC
# define SET_FULLSYNC(x,y)
#endif

/*
** Temporary files are named starting with this prefix followed by 16 random
** alphanumeric characters, and no file extension. They are stored in the
** OS's standard temporary file directory, and are deleted prior to exit.
** If sqlite is being embedded in another program, you may wish to change the
** prefix to reflect your program's name, so that if your program exits
** prematurely, old temporary files can be easily identified. This can be done
** using -DTEMP_FILE_PREFIX=myprefix_ on the compiler command line.
*/
#ifndef TEMP_FILE_PREFIX
# define TEMP_FILE_PREFIX "sqlite_"
#endif

/*
** Define the interfaces for Unix, Windows, and OS/2.
*/
#if OS_UNIX
#define sqlite3OsOpenReadWrite      sqlite3UnixOpenReadWrite
#define sqlite3OsOpenExclusive      sqlite3UnixOpenExclusive
#define sqlite3OsOpenReadOnly       sqlite3UnixOpenReadOnly
#define sqlite3OsDelete             sqlite3UnixDelete
#define sqlite3OsFileExists         sqlite3UnixFileExists
#define sqlite3OsFullPathname       sqlite3UnixFullPathname
#define sqlite3OsIsDirWritable      sqlite3UnixIsDirWritable
#define sqlite3OsSyncDirectory      sqlite3UnixSyncDirectory
#define sqlite3OsTempFileName       sqlite3UnixTempFileName
#define sqlite3OsRandomSeed         sqlite3UnixRandomSeed
#define sqlite3OsSleep              sqlite3UnixSleep
#define sqlite3OsCurrentTime        sqlite3UnixCurrentTime
#define sqlite3OsEnterMutex         sqlite3UnixEnterMutex
#define sqlite3OsLeaveMutex         sqlite3UnixLeaveMutex
#define sqlite3OsInMutex            sqlite3UnixInMutex
#define sqlite3OsThreadSpecificData sqlite3UnixThreadSpecificData
#define sqlite3OsMalloc             sqlite3GenericMalloc
#define sqlite3OsRealloc            sqlite3GenericRealloc
#define sqlite3OsFree               sqlite3GenericFree
#define sqlite3OsAllocationSize     sqlite3GenericAllocationSize
#endif
#if OS_WIN
#define sqlite3OsOpenReadWrite      sqlite3WinOpenReadWrite
#define sqlite3OsOpenExclusive      sqlite3WinOpenExclusive
#define sqlite3OsOpenReadOnly       sqlite3WinOpenReadOnly
#define sqlite3OsDelete             sqlite3WinDelete
#define sqlite3OsFileExists         sqlite3WinFileExists
#define sqlite3OsFullPathname       sqlite3WinFullPathname
#define sqlite3OsIsDirWritable      sqlite3WinIsDirWritable
#define sqlite3OsSyncDirectory      sqlite3WinSyncDirectory
#define sqlite3OsTempFileName       sqlite3WinTempFileName
#define sqlite3OsRandomSeed         sqlite3WinRandomSeed
#define sqlite3OsSleep              sqlite3WinSleep
#define sqlite3OsCurrentTime        sqlite3WinCurrentTime
#define sqlite3OsEnterMutex         sqlite3WinEnterMutex
#define sqlite3OsLeaveMutex         sqlite3WinLeaveMutex
#define sqlite3OsInMutex            sqlite3WinInMutex
#define sqlite3OsThreadSpecificData sqlite3WinThreadSpecificData
#define sqlite3OsMalloc             sqlite3GenericMalloc
#define sqlite3OsRealloc            sqlite3GenericRealloc
#define sqlite3OsFree               sqlite3GenericFree
#define sqlite3OsAllocationSize     sqlite3GenericAllocationSize
#endif
#if OS_OS2
#define sqlite3OsOpenReadWrite      sqlite3Os2OpenReadWrite
#define sqlite3OsOpenExclusive      sqlite3Os2OpenExclusive
#define sqlite3OsOpenReadOnly       sqlite3Os2OpenReadOnly
#define sqlite3OsDelete             sqlite3Os2Delete
#define sqlite3OsFileExists         sqlite3Os2FileExists
#define sqlite3OsFullPathname       sqlite3Os2FullPathname
#define sqlite3OsIsDirWritable      sqlite3Os2IsDirWritable
#define sqlite3OsSyncDirectory      sqlite3Os2SyncDirectory
#define sqlite3OsTempFileName       sqlite3Os2TempFileName
#define sqlite3OsRandomSeed         sqlite3Os2RandomSeed
#define sqlite3OsSleep              sqlite3Os2Sleep
#define sqlite3OsCurrentTime        sqlite3Os2CurrentTime
#define sqlite3OsEnterMutex         sqlite3Os2EnterMutex
#define sqlite3OsLeaveMutex         sqlite3Os2LeaveMutex
#define sqlite3OsInMutex            sqlite3Os2InMutex
#define sqlite3OsThreadSpecificData sqlite3Os2ThreadSpecificData
#define sqlite3OsMalloc             sqlite3GenericMalloc
#define sqlite3OsRealloc            sqlite3GenericRealloc
#define sqlite3OsFree               sqlite3GenericFree
#define sqlite3OsAllocationSize     sqlite3GenericAllocationSize
#endif




/*
** If using an alternative OS interface, then we must have an "os_other.h"
** header file available for that interface.  Presumably the "os_other.h"
** header file contains #defines similar to those above.
*/
#if OS_OTHER
# include "os_other.h"
#endif



/*
** Forward declarations
*/
typedef struct OsFile OsFile;
typedef struct IoMethod IoMethod;

/*
** An instance of the following structure contains pointers to all
** methods on an OsFile object.
*/
struct IoMethod {
  int (*xClose)(OsFile**);
  int (*xOpenDirectory)(OsFile*, const char*);
  int (*xRead)(OsFile*, void*, int amt);
  int (*xWrite)(OsFile*, const void*, int amt);
  int (*xSeek)(OsFile*, i64 offset);
  int (*xTruncate)(OsFile*, i64 size);
  int (*xSync)(OsFile*, int);
  void (*xSetFullSync)(OsFile *id, int setting);
  int (*xFileHandle)(OsFile *id);
  int (*xFileSize)(OsFile*, i64 *pSize);
  int (*xLock)(OsFile*, int);
  int (*xUnlock)(OsFile*, int);
  int (*xLockState)(OsFile *id);
  int (*xCheckReservedLock)(OsFile *id);
};

/*
** The OsFile object describes an open disk file in an OS-dependent way.
** The version of OsFile defined here is a generic version.  Each OS
** implementation defines its own subclass of this structure that contains
** additional information needed to handle file I/O.  But the pMethod
** entry (pointing to the virtual function table) always occurs first
** so that we can always find the appropriate methods.
*/
struct OsFile {
  IoMethod const *pMethod;
};

/*
** The following values may be passed as the second argument to
** sqlite3OsLock(). The various locks exhibit the following semantics:
**
** SHARED:    Any number of processes may hold a SHARED lock simultaneously.
** RESERVED:  A single process may hold a RESERVED lock on a file at
**            any time. Other processes may hold and obtain new SHARED locks.
** PENDING:   A single process may hold a PENDING lock on a file at
**            any one time. Existing SHARED locks may persist, but no new
**            SHARED locks may be obtained by other processes.
** EXCLUSIVE: An EXCLUSIVE lock precludes all other locks.
**
** PENDING_LOCK may not be passed directly to sqlite3OsLock(). Instead, a
** process that requests an EXCLUSIVE lock may actually obtain a PENDING
** lock. This can be upgraded to an EXCLUSIVE lock by a subsequent call to
** sqlite3OsLock().
*/
#define NO_LOCK         0
#define SHARED_LOCK     1
#define RESERVED_LOCK   2
#define PENDING_LOCK    3
#define EXCLUSIVE_LOCK  4

/*
** File Locking Notes:  (Mostly about windows but also some info for Unix)
**
** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because
** those functions are not available.  So we use only LockFile() and
** UnlockFile().
**