441 lines
16 KiB
C
441 lines
16 KiB
C
/*
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** 2001 September 16
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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******************************************************************************
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**
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** This header file (together with is companion C source-code file
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** "os.c") attempt to abstract the underlying operating system so that
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** the SQLite library will work on both POSIX and windows systems.
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*/
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#ifndef _SQLITE_OS_H_
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#define _SQLITE_OS_H_
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/*
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** Figure out if we are dealing with Unix, Windows, or some other
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** operating system.
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*/
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#if !defined(OS_UNIX) && !defined(OS_OTHER)
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# define OS_OTHER 0
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# ifndef OS_WIN
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# if defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) || defined(__MINGW32__) || defined(__BORLANDC__)
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# define OS_WIN 1
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# define OS_UNIX 0
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# else
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# define OS_WIN 0
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# define OS_UNIX 1
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# endif
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# else
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# define OS_UNIX 0
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# endif
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#else
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# ifndef OS_WIN
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# define OS_WIN 0
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# endif
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#endif
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/*
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** Define the maximum size of a temporary filename
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*/
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#if OS_WIN
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# include <windows.h>
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# define SQLITE_TEMPNAME_SIZE (MAX_PATH+50)
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#else
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# define SQLITE_TEMPNAME_SIZE 200
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#endif
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/* If the SET_FULLSYNC macro is not defined above, then make it
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** a no-op
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*/
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#ifndef SET_FULLSYNC
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# define SET_FULLSYNC(x,y)
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#endif
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/*
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** Temporary files are named starting with this prefix followed by 16 random
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** alphanumeric characters, and no file extension. They are stored in the
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** OS's standard temporary file directory, and are deleted prior to exit.
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** If sqlite is being embedded in another program, you may wish to change the
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** prefix to reflect your program's name, so that if your program exits
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** prematurely, old temporary files can be easily identified. This can be done
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** using -DTEMP_FILE_PREFIX=myprefix_ on the compiler command line.
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*/
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#ifndef TEMP_FILE_PREFIX
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# define TEMP_FILE_PREFIX "sqlite_"
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#endif
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/*
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** Define the interfaces for Unix and for Windows.
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*/
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#if OS_UNIX
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#define sqlite3OsOpenReadWrite sqlite3UnixOpenReadWrite
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#define sqlite3OsOpenExclusive sqlite3UnixOpenExclusive
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#define sqlite3OsOpenReadOnly sqlite3UnixOpenReadOnly
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#define sqlite3OsDelete sqlite3UnixDelete
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#define sqlite3OsFileExists sqlite3UnixFileExists
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#define sqlite3OsFullPathname sqlite3UnixFullPathname
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#define sqlite3OsIsDirWritable sqlite3UnixIsDirWritable
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#define sqlite3OsSyncDirectory sqlite3UnixSyncDirectory
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#define sqlite3OsTempFileName sqlite3UnixTempFileName
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#define sqlite3OsRandomSeed sqlite3UnixRandomSeed
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#define sqlite3OsSleep sqlite3UnixSleep
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#define sqlite3OsCurrentTime sqlite3UnixCurrentTime
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#define sqlite3OsEnterMutex sqlite3UnixEnterMutex
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#define sqlite3OsLeaveMutex sqlite3UnixLeaveMutex
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#define sqlite3OsInMutex sqlite3UnixInMutex
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#define sqlite3OsThreadSpecificData sqlite3UnixThreadSpecificData
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#define sqlite3OsMalloc sqlite3GenericMalloc
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#define sqlite3OsRealloc sqlite3GenericRealloc
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#define sqlite3OsFree sqlite3GenericFree
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#define sqlite3OsAllocationSize sqlite3GenericAllocationSize
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#endif
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#if OS_WIN
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#define sqlite3OsOpenReadWrite sqlite3WinOpenReadWrite
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#define sqlite3OsOpenExclusive sqlite3WinOpenExclusive
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#define sqlite3OsOpenReadOnly sqlite3WinOpenReadOnly
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#define sqlite3OsDelete sqlite3WinDelete
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#define sqlite3OsFileExists sqlite3WinFileExists
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#define sqlite3OsFullPathname sqlite3WinFullPathname
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#define sqlite3OsIsDirWritable sqlite3WinIsDirWritable
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#define sqlite3OsSyncDirectory sqlite3WinSyncDirectory
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#define sqlite3OsTempFileName sqlite3WinTempFileName
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#define sqlite3OsRandomSeed sqlite3WinRandomSeed
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#define sqlite3OsSleep sqlite3WinSleep
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#define sqlite3OsCurrentTime sqlite3WinCurrentTime
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#define sqlite3OsEnterMutex sqlite3WinEnterMutex
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#define sqlite3OsLeaveMutex sqlite3WinLeaveMutex
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#define sqlite3OsInMutex sqlite3WinInMutex
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#define sqlite3OsThreadSpecificData sqlite3WinThreadSpecificData
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#define sqlite3OsMalloc sqlite3GenericMalloc
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#define sqlite3OsRealloc sqlite3GenericRealloc
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#define sqlite3OsFree sqlite3GenericFree
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#define sqlite3OsAllocationSize sqlite3GenericAllocationSize
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#endif
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/*
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** If using an alternative OS interface, then we must have an "os_other.h"
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** header file available for that interface. Presumably the "os_other.h"
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** header file contains #defines similar to those above.
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*/
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#if OS_OTHER
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# include "os_other.h"
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#endif
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/*
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** Forward declarations
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*/
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typedef struct OsFile OsFile;
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typedef struct IoMethod IoMethod;
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/*
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** An instance of the following structure contains pointers to all
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** methods on an OsFile object.
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*/
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struct IoMethod {
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int (*xClose)(OsFile**);
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int (*xOpenDirectory)(OsFile*, const char*);
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int (*xRead)(OsFile*, void*, int amt);
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int (*xWrite)(OsFile*, const void*, int amt);
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int (*xSeek)(OsFile*, i64 offset);
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int (*xTruncate)(OsFile*, i64 size);
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int (*xSync)(OsFile*, int);
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void (*xSetFullSync)(OsFile *id, int setting);
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int (*xFileHandle)(OsFile *id);
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int (*xFileSize)(OsFile*, i64 *pSize);
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int (*xLock)(OsFile*, int);
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int (*xUnlock)(OsFile*, int);
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int (*xLockState)(OsFile *id);
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int (*xCheckReservedLock)(OsFile *id);
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};
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/*
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** The OsFile object describes an open disk file in an OS-dependent way.
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** The version of OsFile defined here is a generic version. Each OS
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** implementation defines its own subclass of this structure that contains
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** additional information needed to handle file I/O. But the pMethod
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** entry (pointing to the virtual function table) always occurs first
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** so that we can always find the appropriate methods.
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*/
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struct OsFile {
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IoMethod const *pMethod;
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};
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/*
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** The following values may be passed as the second argument to
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** sqlite3OsLock(). The various locks exhibit the following semantics:
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**
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** SHARED: Any number of processes may hold a SHARED lock simultaneously.
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** RESERVED: A single process may hold a RESERVED lock on a file at
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** any time. Other processes may hold and obtain new SHARED locks.
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** PENDING: A single process may hold a PENDING lock on a file at
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** any one time. Existing SHARED locks may persist, but no new
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** SHARED locks may be obtained by other processes.
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** EXCLUSIVE: An EXCLUSIVE lock precludes all other locks.
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**
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** PENDING_LOCK may not be passed directly to sqlite3OsLock(). Instead, a
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** process that requests an EXCLUSIVE lock may actually obtain a PENDING
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** lock. This can be upgraded to an EXCLUSIVE lock by a subsequent call to
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** sqlite3OsLock().
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*/
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#define NO_LOCK 0
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#define SHARED_LOCK 1
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#define RESERVED_LOCK 2
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#define PENDING_LOCK 3
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#define EXCLUSIVE_LOCK 4
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/*
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** File Locking Notes: (Mostly about windows but also some info for Unix)
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**
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** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because
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** those functions are not available. So we use only LockFile() and
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** UnlockFile().
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**
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** LockFile() prevents not just writing but also reading by other processes.
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** A SHARED_LOCK is obtained by locking a single randomly-chosen
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** byte out of a specific range of bytes. The lock byte is obtained at
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** random so two separate readers can probably access the file at the
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** same time, unless they are unlucky and choose the same lock byte.
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** An EXCLUSIVE_LOCK is obtained by locking all bytes in the range.
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** There can only be one writer. A RESERVED_LOCK is obtained by locking
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** a single byte of the file that is designated as the reserved lock byte.
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** A PENDING_LOCK is obtained by locking a designated byte different from
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** the RESERVED_LOCK byte.
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**
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** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available,
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** which means we can use reader/writer locks. When reader/writer locks
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** are used, the lock is placed on the same range of bytes that is used
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** for probabilistic locking in Win95/98/ME. Hence, the locking scheme
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** will support two or more Win95 readers or two or more WinNT readers.
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** But a single Win95 reader will lock out all WinNT readers and a single
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** WinNT reader will lock out all other Win95 readers.
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**
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** The following #defines specify the range of bytes used for locking.
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** SHARED_SIZE is the number of bytes available in the pool from which
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** a random byte is selected for a shared lock. The pool of bytes for
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** shared locks begins at SHARED_FIRST.
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**
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** These #defines are available in sqlite_aux.h so that adaptors for
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** connecting SQLite to other operating systems can use the same byte
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** ranges for locking. In particular, the same locking strategy and
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** byte ranges are used for Unix. This leaves open the possiblity of having
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** clients on win95, winNT, and unix all talking to the same shared file
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** and all locking correctly. To do so would require that samba (or whatever
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** tool is being used for file sharing) implements locks correctly between
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** windows and unix. I'm guessing that isn't likely to happen, but by
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** using the same locking range we are at least open to the possibility.
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**
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** Locking in windows is manditory. For this reason, we cannot store
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** actual data in the bytes used for locking. The pager never allocates
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** the pages involved in locking therefore. SHARED_SIZE is selected so
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** that all locks will fit on a single page even at the minimum page size.
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** PENDING_BYTE defines the beginning of the locks. By default PENDING_BYTE
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** is set high so that we don't have to allocate an unused page except
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** for very large databases. But one should test the page skipping logic
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** by setting PENDING_BYTE low and running the entire regression suite.
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**
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** Changing the value of PENDING_BYTE results in a subtly incompatible
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** file format. Depending on how it is changed, you might not notice
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** the incompatibility right away, even running a full regression test.
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** The default location of PENDING_BYTE is the first byte past the
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** 1GB boundary.
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**
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*/
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#ifndef SQLITE_TEST
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#define PENDING_BYTE 0x40000000 /* First byte past the 1GB boundary */
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#else
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extern unsigned int sqlite3_pending_byte;
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#define PENDING_BYTE sqlite3_pending_byte
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#endif
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#define RESERVED_BYTE (PENDING_BYTE+1)
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#define SHARED_FIRST (PENDING_BYTE+2)
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#define SHARED_SIZE 510
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/*
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** Prototypes for operating system interface routines.
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*/
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int sqlite3OsClose(OsFile**);
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int sqlite3OsOpenDirectory(OsFile*, const char*);
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int sqlite3OsRead(OsFile*, void*, int amt);
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int sqlite3OsWrite(OsFile*, const void*, int amt);
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int sqlite3OsSeek(OsFile*, i64 offset);
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int sqlite3OsTruncate(OsFile*, i64 size);
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int sqlite3OsSync(OsFile*, int);
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void sqlite3OsSetFullSync(OsFile *id, int setting);
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int sqlite3OsFileHandle(OsFile *id);
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int sqlite3OsFileSize(OsFile*, i64 *pSize);
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int sqlite3OsLock(OsFile*, int);
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int sqlite3OsUnlock(OsFile*, int);
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int sqlite3OsLockState(OsFile *id);
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int sqlite3OsCheckReservedLock(OsFile *id);
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int sqlite3OsOpenReadWrite(const char*, OsFile**, int*);
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int sqlite3OsOpenExclusive(const char*, OsFile**, int);
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int sqlite3OsOpenReadOnly(const char*, OsFile**);
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int sqlite3OsDelete(const char*);
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int sqlite3OsFileExists(const char*);
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char *sqlite3OsFullPathname(const char*);
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int sqlite3OsIsDirWritable(char*);
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int sqlite3OsSyncDirectory(const char*);
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int sqlite3OsTempFileName(char*);
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int sqlite3OsRandomSeed(char*);
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int sqlite3OsSleep(int ms);
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int sqlite3OsCurrentTime(double*);
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void sqlite3OsEnterMutex(void);
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void sqlite3OsLeaveMutex(void);
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int sqlite3OsInMutex(int);
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ThreadData *sqlite3OsThreadSpecificData(int);
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void *sqlite3OsMalloc(int);
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void *sqlite3OsRealloc(void *, int);
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void sqlite3OsFree(void *);
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int sqlite3OsAllocationSize(void *);
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/*
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** If the SQLITE_ENABLE_REDEF_IO macro is defined, then the OS-layer
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** interface routines are not called directly but are invoked using
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** pointers to functions. This allows the implementation of various
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** OS-layer interface routines to be modified at run-time. There are
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** obscure but legitimate reasons for wanting to do this. But for
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** most users, a direct call to the underlying interface is preferable
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** so the the redefinable I/O interface is turned off by default.
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*/
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#ifdef SQLITE_ENABLE_REDEF_IO
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/*
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** When redefinable I/O is enabled, a single global instance of the
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** following structure holds pointers to the routines that SQLite
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** uses to talk with the underlying operating system. Modify this
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** structure (before using any SQLite API!) to accomodate perculiar
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** operating system interfaces or behaviors.
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*/
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struct sqlite3OsVtbl {
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int (*xOpenReadWrite)(const char*, OsFile**, int*);
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int (*xOpenExclusive)(const char*, OsFile**, int);
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int (*xOpenReadOnly)(const char*, OsFile**);
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int (*xDelete)(const char*);
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int (*xFileExists)(const char*);
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char *(*xFullPathname)(const char*);
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int (*xIsDirWritable)(char*);
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int (*xSyncDirectory)(const char*);
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int (*xTempFileName)(char*);
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int (*xRandomSeed)(char*);
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int (*xSleep)(int ms);
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int (*xCurrentTime)(double*);
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void (*xEnterMutex)(void);
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void (*xLeaveMutex)(void);
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int (*xInMutex)(int);
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ThreadData *(*xThreadSpecificData)(int);
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void *(*xMalloc)(int);
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void *(*xRealloc)(void *, int);
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void (*xFree)(void *);
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int (*xAllocationSize)(void *);
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};
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/* Macro used to comment out routines that do not exists when there is
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** no disk I/O
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*/
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#ifdef SQLITE_OMIT_DISKIO
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# define IF_DISKIO(X) 0
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#else
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# define IF_DISKIO(X) X
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#endif
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#ifdef _SQLITE_OS_C_
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/*
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** The os.c file implements the global virtual function table.
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*/
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struct sqlite3OsVtbl sqlite3Os = {
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IF_DISKIO( sqlite3OsOpenReadWrite ),
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IF_DISKIO( sqlite3OsOpenExclusive ),
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IF_DISKIO( sqlite3OsOpenReadOnly ),
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IF_DISKIO( sqlite3OsDelete ),
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IF_DISKIO( sqlite3OsFileExists ),
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IF_DISKIO( sqlite3OsFullPathname ),
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IF_DISKIO( sqlite3OsIsDirWritable ),
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IF_DISKIO( sqlite3OsSyncDirectory ),
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IF_DISKIO( sqlite3OsTempFileName ),
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sqlite3OsRandomSeed,
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sqlite3OsSleep,
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sqlite3OsCurrentTime,
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sqlite3OsEnterMutex,
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sqlite3OsLeaveMutex,
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sqlite3OsInMutex,
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sqlite3OsThreadSpecificData,
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sqlite3OsMalloc,
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sqlite3OsRealloc,
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sqlite3OsFree,
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sqlite3OsAllocationSize
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};
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#else
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/*
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** Files other than os.c just reference the global virtual function table.
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*/
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extern struct sqlite3OsVtbl sqlite3Os;
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#endif /* _SQLITE_OS_C_ */
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/* This additional API routine is available with redefinable I/O */
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struct sqlite3OsVtbl *sqlite3_os_switch(void);
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/*
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** Redefine the OS interface to go through the virtual function table
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** rather than calling routines directly.
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*/
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#undef sqlite3OsOpenReadWrite
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#undef sqlite3OsOpenExclusive
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#undef sqlite3OsOpenReadOnly
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#undef sqlite3OsDelete
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#undef sqlite3OsFileExists
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#undef sqlite3OsFullPathname
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#undef sqlite3OsIsDirWritable
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#undef sqlite3OsSyncDirectory
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#undef sqlite3OsTempFileName
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#undef sqlite3OsRandomSeed
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#undef sqlite3OsSleep
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#undef sqlite3OsCurrentTime
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#undef sqlite3OsEnterMutex
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#undef sqlite3OsLeaveMutex
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#undef sqlite3OsInMutex
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#undef sqlite3OsThreadSpecificData
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#undef sqlite3OsMalloc
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#undef sqlite3OsRealloc
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#undef sqlite3OsFree
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#undef sqlite3OsAllocationSize
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#define sqlite3OsOpenReadWrite sqlite3Os.xOpenReadWrite
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#define sqlite3OsOpenExclusive sqlite3Os.xOpenExclusive
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#define sqlite3OsOpenReadOnly sqlite3Os.xOpenReadOnly
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#define sqlite3OsDelete sqlite3Os.xDelete
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#define sqlite3OsFileExists sqlite3Os.xFileExists
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#define sqlite3OsFullPathname sqlite3Os.xFullPathname
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#define sqlite3OsIsDirWritable sqlite3Os.xIsDirWritable
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#define sqlite3OsSyncDirectory sqlite3Os.xSyncDirectory
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#define sqlite3OsTempFileName sqlite3Os.xTempFileName
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#define sqlite3OsRandomSeed sqlite3Os.xRandomSeed
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#define sqlite3OsSleep sqlite3Os.xSleep
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#define sqlite3OsCurrentTime sqlite3Os.xCurrentTime
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#define sqlite3OsEnterMutex sqlite3Os.xEnterMutex
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#define sqlite3OsLeaveMutex sqlite3Os.xLeaveMutex
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#define sqlite3OsInMutex sqlite3Os.xInMutex
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#define sqlite3OsThreadSpecificData sqlite3Os.xThreadSpecificData
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#define sqlite3OsMalloc sqlite3Os.xMalloc
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#define sqlite3OsRealloc sqlite3Os.xRealloc
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#define sqlite3OsFree sqlite3Os.xFree
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#define sqlite3OsAllocationSize sqlite3Os.xAllocationSize
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#endif /* SQLITE_ENABLE_REDEF_IO */
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#endif /* _SQLITE_OS_H_ */
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