/*
** 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 "os.h" /* Must be first to enable large file support */
#if OS_WIN /* This file is used for windows only */
#include "sqliteInt.h"
#include <winbase.h>
/*
** 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"
/*
** Delete the named file
*/
int sqlite3OsDelete(const char *zFilename){
DeleteFile(zFilename);
return SQLITE_OK;
}
/*
** Return TRUE if the named file exists.
*/
int sqlite3OsFileExists(const char *zFilename){
return GetFileAttributes(zFilename) != 0xffffffff;
}
/*
** Attempt to open a file for both reading and writing. If that
** fails, try opening it read-only. If the file does not exist,
** try to create it.
**
** On success, a handle for the open file is written to *id
** and *pReadonly is set to 0 if the file was opened for reading and
** writing or 1 if the file was opened read-only. The function returns
** SQLITE_OK.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id and *pReadonly unchanged.
*/
int sqlite3OsOpenReadWrite(
const char *zFilename,
OsFile *id,
int *pReadonly
){
HANDLE h = CreateFile(zFilename,
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_ALWAYS,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
NULL
);
if( h==INVALID_HANDLE_VALUE ){
h = CreateFile(zFilename,
GENERIC_READ,
FILE_SHARE_READ,
NULL,
OPEN_ALWAYS,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
NULL
);
if( h==INVALID_HANDLE_VALUE ){
return SQLITE_CANTOPEN;
}
*pReadonly = 1;
}else{
*pReadonly = 0;
}
id->h = h;
id->locked = 0;
OpenCounter(+1);
return SQLITE_OK;
}
/*
** Attempt to open a new file for exclusive access by this process.
** The file will be opened for both reading and writing. To avoid
** a potential security problem, we do not allow the file to have
** previously existed. Nor do we allow the file to be a symbolic
** link.
**
** If delFlag is true, then make arrangements to automatically delete
** the file when it is closed.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqlite3OsOpenExclusive(const char *zFilename, OsFile *id, int delFlag){
HANDLE h;
int fileflags;
if( delFlag ){
fileflags = FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_RANDOM_ACCESS
| FILE_FLAG_DELETE_ON_CLOSE;
}else{
fileflags = FILE_FLAG_RANDOM_ACCESS;
}
h = CreateFile(zFilename,
GENERIC_READ | GENERIC_WRITE,
0,
NULL,
CREATE_ALWAYS,
fileflags,
NULL
);
if( h==INVALID_HANDLE_VALUE ){
return SQLITE_CANTOPEN;
}
id->h = h;
id->locked = 0;
OpenCounter(+1);
return SQLITE_OK;
}
/*
** Attempt to open a new file for read-only access.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqlite3OsOpenReadOnly(const char *zFilename, OsFile *id){
HANDLE h = CreateFile(zFilename,
GENERIC_READ,
0,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
NULL
);
if( h==INVALID_HANDLE_VALUE ){
return SQLITE_CANTOPEN;
}
id->h = h;
id->locked = 0;
OpenCounter(+1);
return SQLITE_OK;
}
/*
** Attempt to open a file descriptor for the directory that contains a
** file. This file descriptor can be used to fsync() the directory
** in order to make sure the creation of a new file is actually written
** to disk.
**
** This routine is only meaningful for Unix. It is a no-op under
** windows since windows does not support hard links.
**
** On success, a handle for a previously open file is at *id is
** updated with the new directory file descriptor and SQLITE_OK is
** returned.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id unchanged.
*/
int sqlite3OsOpenDirectory(
const char *zDirname,
OsFile *id
){
return SQLITE_OK;
}
/*
** Create a temporary file name in zBuf. zBuf must be big enough to
** hold at least SQLITE_TEMPNAME_SIZE characters.
*/
int sqlite3OsTempFileName(char *zBuf){
static char zChars[] =
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"0123456789";
int i, j;
char zTempPath[SQLITE_TEMPNAME_SIZE];
GetTempPath(SQLITE_TEMPNAME_SIZE-30, zTempPath);
for(i=strlen(zTempPath); i>0 && zTempPath[i-1]=='\\'; i--){}
zTempPath[i] = 0;
for(;;){
sprintf(zBuf, "%s\\"TEMP_FILE_PREFIX, zTempPath);
j = strlen(zBuf);
sqlite3Randomness(15, &zBuf[j]);
for(i=0; i<15; i++, j++){
zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
}
zBuf[j] = 0;
if( !sqlite3OsFileExists(zBuf) ) break;
}
return SQLITE_OK;
}
/*
** Close a file.
*/
int sqlite3OsClose(OsFile *id){
CloseHandle(id->h);
OpenCounter(-1);
return SQLITE_OK;
}
/*
** Read data from a file into a buffer. Return SQLITE_OK if all
** bytes were read successfully and SQLITE_IOERR if anything goes
** wrong.
*/
int sqlite3OsRead(OsFile *id, void *pBuf, int amt){
DWORD got;
SimulateIOError(SQLITE_IOERR);
TRACE2("READ %d\n", last_page);
if( !ReadFile(id->h, pBuf, amt, &got, 0) ){
got = 0;
}
if( got==(DWORD)amt ){
return SQLITE_OK;
}else{
return SQLITE_IOERR;
}
}
/*
** Write data from a buffer into a file. Return SQLITE_OK on success
** or some other error code on failure.
*/
int sqlite3OsWrite(OsFile *id, const void *pBuf, int amt){
int rc;
DWORD wrote;
SimulateIOError(SQLITE_IOERR);
TRACE2("WRITE %d\n", last_page);
while( amt>0 && (rc = WriteFile(id->h, pBuf, amt, &wrote, 0))!=0 && wrote>0 ){
amt -= wrote;
pBuf = &((char*)pBuf)[wrote];
}
if( !rc || amt>(int)wrote ){
return SQLITE_FULL;
}
return SQLITE_OK;
}
/*
** Move the read/write pointer in a file.
*/
int sqlite3OsSeek(OsFile *id, off_t offset){
LONG upperBits = offset>>32;
LONG lowerBits = offset & 0xffffffff;
DWORD rc;
SEEK(offset/1024 + 1);
rc = SetFilePointer(id->h, lowerBits, &upperBits, FILE_BEGIN);
/* TRACE3("SEEK rc=0x%x upper=0x%x\n", rc, upperBits); */
return SQLITE_OK;
}
/*
** Make sure all writes to a particular file are committed to disk.
*/
int sqlite3OsSync(OsFile *id){
if( FlushFileBuffers(id->h) ){
return SQLITE_OK;
}else{
return SQLITE_IOERR;
}
}
/*
** Truncate an open file to a specified size
*/
int sqlite3OsTruncate(OsFile *id, off_t nByte){
LONG upperBits = nByte>>32;
SimulateIOError(SQLITE_IOERR);
SetFilePointer(id->h, nByte, &upperBits, FILE_BEGIN);
SetEndOfFile(id->h);
return SQLITE_OK;
}
/*
** Determine the current size of a file in bytes
*/
int sqlite3OsFileSize(OsFile *id, off_t *pSize){
DWORD upperBits, lowerBits;
SimulateIOError(SQLITE_IOERR);
lowerBits = GetFileSize(id->h, &upperBits);
*pSize = (((off_t)upperBits)<<32) + lowerBits;
return SQLITE_OK;
}
/*
** Return true (non-zero) if we are running under WinNT, Win2K or WinXP.
** 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.
*/
int isNT(void){
static int osType = 0; /* 0=unknown 1=win95 2=winNT */
if( osType==0 ){
OSVERSIONINFO sInfo;
sInfo.dwOSVersionInfoSize = sizeof(sInfo);
GetVersionEx(&sInfo);
osType = sInfo.dwPlatformId==VER_PLATFORM_WIN32_NT ? 2 : 1;
}
return osType==2;
}
/*
** Windows file locking notes:
**
** 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.
** (This is a design error on the part of Windows, but there is nothing
** we can do about that.) So the region used for locking is at the
** end of the file where it is unlikely to ever interfere with an
** actual read attempt.
**
** A database read 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.
** A database write lock is obtained by locking all bytes in the range.
** There can only be one writer.
**
** A lock is obtained on the first byte of the lock range before acquiring
** either a read lock or a write lock. This prevents two processes from
** attempting to get a lock at a same time. The semantics of
** sqlite3OsReadLock() require that if there is already a write lock, that
** lock is converted into a read lock atomically. The lock on the first
** byte allows us to drop the old write lock and get the read lock without
** another process jumping into the middle and messing us up. The same
** argument applies to sqlite3OsWriteLock().
**
** 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.
** N_LOCKBYTE is the number of bytes available for doing the locking.
** The first byte used to hold the lock while the lock is changing does
** not count toward this number. FIRST_LOCKBYTE is the address of
** the first byte in the range of bytes used for locking.
*/
#define N_LOCKBYTE 10239
#define FIRST_LOCKBYTE (0xffffffff - N_LOCKBYTE)
/*
** Change the status of the lock on the file "id" to be a readlock.
** If the file was write locked, then this reduces the lock to a read.
** If the file was read locked, then this acquires a new read lock.
**
** Return SQLITE_OK on success and SQLITE_BUSY on failure. If this
** library was compiled with large file support (LFS) but LFS is not
** available on the host, then an SQLITE_NOLFS is returned.
*/
int sqlite3OsReadLock(OsFile *id){
int rc;
if( id->locked>0 ){
rc = SQLITE_OK;
}else{
int lk;
int res;
int cnt = 100;
sqlite3Randomness(sizeof(lk), &lk);
lk = (lk & 0x7fffffff)%N_LOCKBYTE + 1;
while( cnt-->0 && (res = LockFile(id->h, FIRST_LOCKBYTE, 0, 1, 0))==0 ){
Sleep(1);
}
if( res ){
UnlockFile(id->h, FIRST_LOCKBYTE+1, 0, N_LOCKBYTE, 0);
if( isNT() ){
OVERLAPPED ovlp;
ovlp.Offset = FIRST_LOCKBYTE+1;
ovlp.OffsetHigh = 0;
ovlp.hEvent = 0;
res = LockFileEx(id->h, LOCKFILE_FAIL_IMMEDIATELY,
0, N_LOCKBYTE, 0, &ovlp);
}else{
res = LockFile(id->h, FIRST_LOCKBYTE+lk, 0, 1, 0);
}
UnlockFile(id->h, FIRST_LOCKBYTE, 0, 1, 0);
}
if( res ){
id->locked = lk;
rc = SQLITE_OK;
}else{
rc = SQLITE_BUSY;
}
}
return rc;
}
/*
** Change the lock status to be an exclusive or write lock. Return
** SQLITE_OK on success and SQLITE_BUSY on a failure. If this
** library was compiled with large file support (LFS) but LFS is not
** available on the host, then an SQLITE_NOLFS is returned.
*/
int sqlite3OsWriteLock(OsFile *id){
int rc;
if( id->locked<0 ){
rc = SQLITE_OK;
}else{
int res;
int cnt = 100;
while( cnt-->0 && (res = LockFile(id->h, FIRST_LOCKBYTE, 0, 1, 0))==0 ){
Sleep(1);
}
if( res ){
if( id->locked>0 ){
if( isNT() ){
UnlockFile(id->h, FIRST_LOCKBYTE+1, 0, N_LOCKBYTE, 0);
}else{
res = UnlockFile(id->h, FIRST_LOCKBYTE + id->locked, 0, 1, 0);
}
}
if( res ){
res = LockFile(id->h, FIRST_LOCKBYTE+1, 0, N_LOCKBYTE, 0);
}else{
res = 0;
}
UnlockFile(id->h, FIRST_LOCKBYTE, 0, 1, 0);
}
if( res ){
id->locked = -1;
rc = SQLITE_OK;
}else{
rc = SQLITE_BUSY;
}
}
return rc;
}
/*
** Unlock the given file descriptor. If the file descriptor was
** not previously locked, then this routine is a no-op. If this
** library was compiled with large file support (LFS) but LFS is not
** available on the host, then an SQLITE_NOLFS is returned.
*/
int sqlite3OsUnlock(OsFile *id){
int rc;
if( id->locked==0 ){
rc = SQLITE_OK;
}else if( isNT() || id->locked<0 ){
UnlockFile(id->h, FIRST_LOCKBYTE+1, 0, N_LOCKBYTE, 0);
rc = SQLITE_OK;
id->locked = 0;
}else{
UnlockFile(id->h, FIRST_LOCKBYTE+id->locked, 0, 1, 0);
rc = SQLITE_OK;
id->locked = 0;
}
return rc;
}
/*
** Get information to seed the random number generator. The seed
** is written into the buffer zBuf[256]. The calling function must
** supply a sufficiently large buffer.
*/
int sqlite3OsRandomSeed(char *zBuf){
/* We have to initialize zBuf to prevent valgrind from reporting
** errors. The reports issued by valgrind are incorrect - we would
** prefer that the randomness be increased by making use of the
** uninitialized space in zBuf - but valgrind errors tend to worry
** some users. Rather than argue, it seems easier just to initialize
** the whole array and silence valgrind, even if that means less randomness
** in the random seed.
**
** When testing, initializing zBuf[] to zero is all we do. That means
** that we always use the same random number sequence.* This makes the
** tests repeatable.
*/
memset(zBuf, 0, 256);
GetSystemTime((LPSYSTEMTIME)zBuf);
return SQLITE_OK;
}
/*
** Sleep for a little while. Return the amount of time slept.
*/
int sqlite3OsSleep(int ms){
Sleep(ms);
return ms;
}
/*
** Static variables used for thread synchronization
*/
static int inMutex = 0;
#ifdef SQLITE_W32_THREADS
static CRITICAL_SECTION cs;
#endif
/*
** The following pair of routine implement mutual exclusion for
** multi-threaded processes. Only a single thread is allowed to
** executed code that is surrounded by EnterMutex() and LeaveMutex().
**
** SQLite uses only a single Mutex. There is not much critical
** code and what little there is executes quickly and without blocking.
*/
void sqlite3OsEnterMutex(){
#ifdef SQLITE_W32_THREADS
static int isInit = 0;
while( !isInit ){
static long lock = 0;
if( InterlockedIncrement(&lock)==1 ){
InitializeCriticalSection(&cs);
isInit = 1;
}else{
Sleep(1);
}
}
EnterCriticalSection(&cs);
#endif
assert( !inMutex );
inMutex = 1;
}
void sqlite3OsLeaveMutex(){
assert( inMutex );
inMutex = 0;
#ifdef SQLITE_W32_THREADS
LeaveCriticalSection(&cs);
#endif
}
/*
** Turn a relative pathname into a full pathname. Return a pointer
** to the full pathname stored in space obtained from sqliteMalloc().
** The calling function is responsible for freeing this space once it
** is no longer needed.
*/
char *sqlite3OsFullPathname(const char *zRelative){
char *zNotUsed;
char *zFull;
int nByte;
nByte = GetFullPathName(zRelative, 0, 0, &zNotUsed) + 1;
zFull = sqliteMalloc( nByte );
if( zFull==0 ) return 0;
GetFullPathName(zRelative, nByte, zFull, &zNotUsed);
return zFull;
}
/*
** The following variable, if set to a non-zero value, becomes the result
** returned from sqlite3OsCurrentTime(). This is used for testing.
*/
#ifdef SQLITE_TEST
int sqlite3_current_time = 0;
#endif
/*
** Find the current time (in Universal Coordinated Time). Write the
** current time and date as a Julian Day number into *prNow and
** return 0. Return 1 if the time and date cannot be found.
*/
int sqlite3OsCurrentTime(double *prNow){
FILETIME ft;
/* FILETIME structure is a 64-bit value representing the number of
100-nanosecond intervals since January 1, 1601 (= JD 2305813.5).
*/
double now;
GetSystemTimeAsFileTime( &ft );
now = ((double)ft.dwHighDateTime) * 4294967296.0;
*prNow = (now + ft.dwLowDateTime)/864000000000.0 + 2305813.5;
#ifdef SQLITE_TEST
if( sqlite3_current_time ){
*prNow = sqlite3_current_time/86400.0 + 2440587.5;
}
#endif
return 0;
}
#endif /* OS_WIN */