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Diffstat (limited to 'src/os_win.c')
| -rw-r--r-- | src/os_win.c | 601 |
1 files changed, 601 insertions, 0 deletions
diff --git a/src/os_win.c b/src/os_win.c new file mode 100644 index 000000000..9c21f7cd0 --- /dev/null +++ b/src/os_win.c @@ -0,0 +1,601 @@ +/* +** 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 */ |