/*

 ** 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_OTHER)

 # if OS_OTHER==1

 #   undef OS_UNIX

 #   define OS_UNIX 0

 #   undef OS_WIN

 #   define OS_WIN 0

 #   undef OS_OS2

 #   define OS_OS2 0

 # else

 #   undef OS_OTHER

 # endif

 #endif

 #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

 # if (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ >= 3) && defined(OS2_HIGH_MEMORY)

 #  include <os2safe.h> /* has to be included before os2.h for linking to work */

 # endif

 # define INCL_DOSDATETIME

 # define INCL_DOSFILEMGR

 # define INCL_DOSERRORS

 # define INCL_DOSMISC

 # define INCL_DOSPROCESS

 # define INCL_DOSMODULEMGR

 # 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

 /*

 ** The default size of a disk sector

 */

 #ifndef SQLITE_DEFAULT_SECTOR_SIZE

 # define SQLITE_DEFAULT_SECTOR_SIZE 512

 #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.

 **

 ** 2006-10-31:  The default prefix used to be "sqlite_".  But then

 ** Mcafee started using SQLite in their anti-virus product and it

 ** started putting files with the "sqlite" name in the c:/temp folder.

 ** This annoyed many windows users.  Those users would then do a 

 ** Google search for "sqlite", find the telephone numbers of the

 ** developers and call to wake them up at night and complain.

 ** For this reason, the default name prefix is changed to be "sqlite" 

 ** spelled backwards.  So the temp files are still identified, but

 ** anybody smart enough to figure out the code is also likely smart

 ** enough to know that calling the developer will not help get rid

 ** of the file.

 */

 #ifndef TEMP_FILE_PREFIX

 # define TEMP_FILE_PREFIX "etilqs_"

 #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

 #define sqlite3OsDlopen             sqlite3UnixDlopen

 #define sqlite3OsDlsym              sqlite3UnixDlsym

 #define sqlite3OsDlclose            sqlite3UnixDlclose

 #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

 #define sqlite3OsDlopen             sqlite3WinDlopen

 #define sqlite3OsDlsym              sqlite3WinDlsym

 #define sqlite3OsDlclose            sqlite3WinDlclose

 #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

 #define sqlite3OsDlopen             sqlite3Os2Dlopen

 #define sqlite3OsDlsym              sqlite3Os2Dlsym

 #define sqlite3OsDlclose            sqlite3Os2Dlclose

 #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);

   int (*xSectorSize)(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().

 **

 ** LockFile() prevents not just writing but also reading by other processes.

 ** A SHARED_LOCK is obtained by locking a single randomly-chosen 

 ** byte out of a specific range of bytes. The lock byte is obtained at 

 ** random so two separate readers can probably access the file at the 

 ** same time, unless they are unlucky and choose the same lock byte.

 ** An EXCLUSIVE_LOCK is obtained by locking all bytes in the range.

 ** There can only be one writer.  A RESERVED_LOCK is obtained by locking

 ** a single byte of the file that is designated as the reserved lock byte.

 ** A PENDING_LOCK is obtained by locking a designated byte different from

 ** the RESERVED_LOCK byte.

 **

 ** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available,

 ** which means we can use reader/writer locks.  When reader/writer locks

 ** are used, the lock is placed on the same range of bytes that is used

 ** for probabilistic locking in Win95/98/ME.  Hence, the locking scheme

 ** will support two or more Win95 readers or two or more WinNT readers.

 ** But a single Win95 reader will lock out all WinNT readers and a single

 ** WinNT reader will lock out all other Win95 readers.

 **

 ** The following #defines specify the range of bytes used for locking.

 ** SHARED_SIZE is the number of bytes available in the pool from which

 ** a random byte is selected for a shared lock.  The pool of bytes for

 ** shared locks begins at SHARED_FIRST. 

 **

 ** These #defines are available in sqlite_aux.h so that adaptors for

 ** connecting SQLite to other operating systems can use the same byte

 ** ranges for locking.  In particular, the same locking strategy and

 ** byte ranges are used for Unix.  This leaves open the possiblity of having

 ** clients on win95, winNT, and unix all talking to the same shared file

 ** and all locking correctly.  To do so would require that samba (or whatever

 ** tool is being used for file sharing) implements locks correctly between

 ** windows and unix.  I'm guessing that isn't likely to happen, but by

 ** using the same locking range we are at least open to the possibility.

 **

 ** Locking in windows is manditory.  For this reason, we cannot store

 ** actual data in the bytes used for locking.  The pager never allocates

 ** the pages involved in locking therefore.  SHARED_SIZE is selected so

 ** that all locks will fit on a single page even at the minimum page size.

 ** PENDING_BYTE defines the beginning of the locks.  By default PENDING_BYTE

 ** is set high so that we don't have to allocate an unused page except

 ** for very large databases.  But one should test the page skipping logic 

 ** by setting PENDING_BYTE low and running the entire regression suite.

 **

 ** Changing the value of PENDING_BYTE results in a subtly incompatible

 ** file format.  Depending on how it is changed, you might not notice

 ** the incompatibility right away, even running a full regression test.

 ** The default location of PENDING_BYTE is the first byte past the

 ** 1GB boundary.

 **

 */

 #ifndef SQLITE_TEST

 #define PENDING_BYTE      0x40000000  /* First byte past the 1GB boundary */

 #else

 extern unsigned int sqlite3_pending_byte;

 #define PENDING_BYTE sqlite3_pending_byte

 #endif

 #define RESERVED_BYTE     (PENDING_BYTE+1)

 #define SHARED_FIRST      (PENDING_BYTE+2)

 #define SHARED_SIZE       510

 /*

 ** Prototypes for operating system interface routines.

 */

 int sqlite3OsClose(OsFile**);

 int sqlite3OsOpenDirectory(OsFile*, const char*);

 int sqlite3OsRead(OsFile*, void*, int amt);

 int sqlite3OsWrite(OsFile*, const void*, int amt);

 int sqlite3OsSeek(OsFile*, i64 offset);

 int sqlite3OsTruncate(OsFile*, i64 size);

 int sqlite3OsSync(OsFile*, int);

 void sqlite3OsSetFullSync(OsFile *id, int setting);

 int sqlite3OsFileSize(OsFile*, i64 *pSize);

 int sqlite3OsLock(OsFile*, int);

 int sqlite3OsUnlock(OsFile*, int);

 int sqlite3OsCheckReservedLock(OsFile *id);

 int sqlite3OsOpenReadWrite(const char*, OsFile**, int*);

 int sqlite3OsOpenExclusive(const char*, OsFile**, int);

 int sqlite3OsOpenReadOnly(const char*, OsFile**);

 int sqlite3OsDelete(const char*);

 int sqlite3OsFileExists(const char*);

 char *sqlite3OsFullPathname(const char*);

 int sqlite3OsIsDirWritable(char*);

 int sqlite3OsSyncDirectory(const char*);

 int sqlite3OsSectorSize(OsFile *id);

 int sqlite3OsTempFileName(char*);

 int sqlite3OsRandomSeed(char*);

 int sqlite3OsSleep(int ms);

 int sqlite3OsCurrentTime(double*);

 void sqlite3OsEnterMutex(void);

 void sqlite3OsLeaveMutex(void);

 int sqlite3OsInMutex(int);

 ThreadData *sqlite3OsThreadSpecificData(int);

 void *sqlite3OsMalloc(int);

 void *sqlite3OsRealloc(void *, int);

 void sqlite3OsFree(void *);

 int sqlite3OsAllocationSize(void *);

 void *sqlite3OsDlopen(const char*);

 void *sqlite3OsDlsym(void*, const char*);

 int sqlite3OsDlclose(void*);

 #if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)

   int sqlite3OsFileHandle(OsFile *id);

   int sqlite3OsLockState(OsFile *id);

 #endif

 /*

 ** If the SQLITE_ENABLE_REDEF_IO macro is defined, then the OS-layer

 ** interface routines are not called directly but are invoked using

 ** pointers to functions.  This allows the implementation of various

 ** OS-layer interface routines to be modified at run-time.  There are

 ** obscure but legitimate reasons for wanting to do this.  But for

 ** most users, a direct call to the underlying interface is preferable

 ** so the the redefinable I/O interface is turned off by default.

 */

 #ifdef SQLITE_ENABLE_REDEF_IO

 /*

 ** When redefinable I/O is enabled, a single global instance of the

 ** following structure holds pointers to the routines that SQLite 

 ** uses to talk with the underlying operating system.  Modify this

 ** structure (before using any SQLite API!) to accomodate perculiar

 ** operating system interfaces or behaviors.

 */

 struct sqlite3OsVtbl {

   int (*xOpenReadWrite)(const char*, OsFile**, int*);

   int (*xOpenExclusive)(const char*, OsFile**, int);

   int (*xOpenReadOnly)(const char*, OsFile**);

   int (*xDelete)(const char*);

   int (*xFileExists)(const char*);

   char *(*xFullPathname)(const char*);

   int (*xIsDirWritable)(char*);

   int (*xSyncDirectory)(const char*);

   int (*xTempFileName)(char*);

   int (*xRandomSeed)(char*);

   int (*xSleep)(int ms);

   int (*xCurrentTime)(double*);

   void (*xEnterMutex)(void);

   void (*xLeaveMutex)(void);

   int (*xInMutex)(int);

   ThreadData *(*xThreadSpecificData)(int);

   void *(*xMalloc)(int);

   void *(*xRealloc)(void *, int);

   void (*xFree)(void *);

   int (*xAllocationSize)(void *);

   void *(*xDlopen)(const char*);

   void *(*xDlsym)(void*, const char*);

   int (*xDlclose)(void*);

 };

 /* Macro used to comment out routines that do not exists when there is

 ** no disk I/O or extension loading

 */

 #ifdef SQLITE_OMIT_DISKIO

 # define IF_DISKIO(X)  0

 #else

 # define IF_DISKIO(X)  X

 #endif

 #ifdef SQLITE_OMIT_LOAD_EXTENSION

 # define IF_DLOPEN(X)  0

 #else

 # define IF_DLOPEN(X)  X

 #endif

 #if defined(_SQLITE_OS_C_) || defined(SQLITE_AMALGAMATION)

   /*

   ** The os.c file implements the global virtual function table.

   ** We have to put this file here because the initializers

   ** (ex: sqlite3OsRandomSeed) are macros that are about to be

   ** redefined.

   */

   struct sqlite3OsVtbl sqlite3Os = {

     IF_DISKIO( sqlite3OsOpenReadWrite ),

     IF_DISKIO( sqlite3OsOpenExclusive ),

     IF_DISKIO( sqlite3OsOpenReadOnly ),

     IF_DISKIO( sqlite3OsDelete ),

     IF_DISKIO( sqlite3OsFileExists ),

     IF_DISKIO( sqlite3OsFullPathname ),

     IF_DISKIO( sqlite3OsIsDirWritable ),

     IF_DISKIO( sqlite3OsSyncDirectory ),

     IF_DISKIO( sqlite3OsTempFileName ),

     sqlite3OsRandomSeed,

     sqlite3OsSleep,

     sqlite3OsCurrentTime,

     sqlite3OsEnterMutex,

     sqlite3OsLeaveMutex,

     sqlite3OsInMutex,

     sqlite3OsThreadSpecificData,

     sqlite3OsMalloc,

     sqlite3OsRealloc,

     sqlite3OsFree,

     sqlite3OsAllocationSize,

     IF_DLOPEN( sqlite3OsDlopen ),

     IF_DLOPEN( sqlite3OsDlsym ),

     IF_DLOPEN( sqlite3OsDlclose ),

   };

 #else

   /*

   ** Files other than os.c just reference the global virtual function table. 

   */

   extern struct sqlite3OsVtbl sqlite3Os;

 #endif /* _SQLITE_OS_C_ */

 /* This additional API routine is available with redefinable I/O */

 struct sqlite3OsVtbl *sqlite3_os_switch(void);

 /*

 ** Redefine the OS interface to go through the virtual function table

 ** rather than calling routines directly.

 */

 #undef sqlite3OsOpenReadWrite

 #undef sqlite3OsOpenExclusive

 #undef sqlite3OsOpenReadOnly

 #undef sqlite3OsDelete

 #undef sqlite3OsFileExists

 #undef sqlite3OsFullPathname

 #undef sqlite3OsIsDirWritable

 #undef sqlite3OsSyncDirectory

 #undef sqlite3OsTempFileName

 #undef sqlite3OsRandomSeed

 #undef sqlite3OsSleep

 #undef sqlite3OsCurrentTime

 #undef sqlite3OsEnterMutex

 #undef sqlite3OsLeaveMutex

 #undef sqlite3OsInMutex

 #undef sqlite3OsThreadSpecificData

 #undef sqlite3OsMalloc

 #undef sqlite3OsRealloc

 #undef sqlite3OsFree

 #undef sqlite3OsAllocationSize

 #define sqlite3OsOpenReadWrite      sqlite3Os.xOpenReadWrite

 #define sqlite3OsOpenExclusive      sqlite3Os.xOpenExclusive

 #define sqlite3OsOpenReadOnly       sqlite3Os.xOpenReadOnly

 #define sqlite3OsDelete             sqlite3Os.xDelete

 #define sqlite3OsFileExists         sqlite3Os.xFileExists

 #define sqlite3OsFullPathname       sqlite3Os.xFullPathname

 #define sqlite3OsIsDirWritable      sqlite3Os.xIsDirWritable

 #define sqlite3OsSyncDirectory      sqlite3Os.xSyncDirectory

 #define sqlite3OsTempFileName       sqlite3Os.xTempFileName

 #define sqlite3OsRandomSeed         sqlite3Os.xRandomSeed

 #define sqlite3OsSleep              sqlite3Os.xSleep

 #define sqlite3OsCurrentTime        sqlite3Os.xCurrentTime

 #define sqlite3OsEnterMutex         sqlite3Os.xEnterMutex

 #define sqlite3OsLeaveMutex         sqlite3Os.xLeaveMutex

 #define sqlite3OsInMutex            sqlite3Os.xInMutex

 #define sqlite3OsThreadSpecificData sqlite3Os.xThreadSpecificData

 #define sqlite3OsMalloc             sqlite3Os.xMalloc

 #define sqlite3OsRealloc            sqlite3Os.xRealloc

 #define sqlite3OsFree               sqlite3Os.xFree

 #define sqlite3OsAllocationSize     sqlite3Os.xAllocationSize

 #endif /* SQLITE_ENABLE_REDEF_IO */

 #endif /* _SQLITE_OS_H_ */