/* ** 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 Unix systems. ** ** $Id: os_unix.c,v 1.203 2008/09/23 10:23:26 drh Exp $ */ #include "sqliteInt.h" #if SQLITE_OS_UNIX /* This file is used on unix only */ /* ** If SQLITE_ENABLE_LOCKING_STYLE is defined and is non-zero, then several ** alternative locking implementations are provided: ** ** * POSIX locking (the default), ** * No locking, ** * Dot-file locking, ** * flock() locking, ** * AFP locking (OSX only). ** ** SQLITE_ENABLE_LOCKING_STYLE only works on a Mac. It is turned on by ** default on a Mac and disabled on all other posix platforms. */ #if !defined(SQLITE_ENABLE_LOCKING_STYLE) # if defined(__DARWIN__) # define SQLITE_ENABLE_LOCKING_STYLE 1 # else # define SQLITE_ENABLE_LOCKING_STYLE 0 # endif #endif /* ** These #defines should enable >2GB file support on Posix if the ** underlying operating system supports it. If the OS lacks ** large file support, these should be no-ops. ** ** Large file support can be disabled using the -DSQLITE_DISABLE_LFS switch ** on the compiler command line. This is necessary if you are compiling ** on a recent machine (ex: RedHat 7.2) but you want your code to work ** on an older machine (ex: RedHat 6.0). If you compile on RedHat 7.2 ** without this option, LFS is enable. But LFS does not exist in the kernel ** in RedHat 6.0, so the code won't work. Hence, for maximum binary ** portability you should omit LFS. */ #ifndef SQLITE_DISABLE_LFS # define _LARGE_FILE 1 # ifndef _FILE_OFFSET_BITS # define _FILE_OFFSET_BITS 64 # endif # define _LARGEFILE_SOURCE 1 #endif /* ** standard include files. */ #include #include #include #include #include #include #include #if SQLITE_ENABLE_LOCKING_STYLE #include #include #include #endif /* SQLITE_ENABLE_LOCKING_STYLE */ /* ** If we are to be thread-safe, include the pthreads header and define ** the SQLITE_UNIX_THREADS macro. */ #if SQLITE_THREADSAFE # include # define SQLITE_UNIX_THREADS 1 #endif /* ** Default permissions when creating a new file */ #ifndef SQLITE_DEFAULT_FILE_PERMISSIONS # define SQLITE_DEFAULT_FILE_PERMISSIONS 0644 #endif /* ** Maximum supported path-length. */ #define MAX_PATHNAME 512 /* ** The unixFile structure is subclass of sqlite3_file specific for the unix ** protability layer. */ typedef struct unixFile unixFile; struct unixFile { sqlite3_io_methods const *pMethod; /* Always the first entry */ #ifdef SQLITE_TEST /* In test mode, increase the size of this structure a bit so that ** it is larger than the struct CrashFile defined in test6.c. */ char aPadding[32]; #endif struct openCnt *pOpen; /* Info about all open fd's on this inode */ struct lockInfo *pLock; /* Info about locks on this inode */ #if SQLITE_ENABLE_LOCKING_STYLE void *lockingContext; /* Locking style specific state */ #endif int h; /* The file descriptor */ unsigned char locktype; /* The type of lock held on this fd */ int dirfd; /* File descriptor for the directory */ #if SQLITE_THREADSAFE pthread_t tid; /* The thread that "owns" this unixFile */ #endif int lastErrno; /* The unix errno from the last I/O error */ }; /* ** Include code that is common to all os_*.c files */ #include "os_common.h" /* ** Define various macros that are missing from some systems. */ #ifndef O_LARGEFILE # define O_LARGEFILE 0 #endif #ifdef SQLITE_DISABLE_LFS # undef O_LARGEFILE # define O_LARGEFILE 0 #endif #ifndef O_NOFOLLOW # define O_NOFOLLOW 0 #endif #ifndef O_BINARY # define O_BINARY 0 #endif /* ** The DJGPP compiler environment looks mostly like Unix, but it ** lacks the fcntl() system call. So redefine fcntl() to be something ** that always succeeds. This means that locking does not occur under ** DJGPP. But it is DOS - what did you expect? */ #ifdef __DJGPP__ # define fcntl(A,B,C) 0 #endif /* ** The threadid macro resolves to the thread-id or to 0. Used for ** testing and debugging only. */ #if SQLITE_THREADSAFE #define threadid pthread_self() #else #define threadid 0 #endif /* ** Set or check the unixFile.tid field. This field is set when an unixFile ** is first opened. All subsequent uses of the unixFile verify that the ** same thread is operating on the unixFile. Some operating systems do ** not allow locks to be overridden by other threads and that restriction ** means that sqlite3* database handles cannot be moved from one thread ** to another. This logic makes sure a user does not try to do that ** by mistake. ** ** Version 3.3.1 (2006-01-15): unixFile can be moved from one thread to ** another as long as we are running on a system that supports threads ** overriding each others locks (which now the most common behavior) ** or if no locks are held. But the unixFile.pLock field needs to be ** recomputed because its key includes the thread-id. See the ** transferOwnership() function below for additional information */ #if SQLITE_THREADSAFE # define SET_THREADID(X) (X)->tid = pthread_self() # define CHECK_THREADID(X) (threadsOverrideEachOthersLocks==0 && \ !pthread_equal((X)->tid, pthread_self())) #else # define SET_THREADID(X) # define CHECK_THREADID(X) 0 #endif /* ** Here is the dirt on POSIX advisory locks: ANSI STD 1003.1 (1996) ** section 6.5.2.2 lines 483 through 490 specify that when a process ** sets or clears a lock, that operation overrides any prior locks set ** by the same process. It does not explicitly say so, but this implies ** that it overrides locks set by the same process using a different ** file descriptor. Consider this test case: ** int fd2 = open("./file2", O_RDWR|O_CREAT, 0644); ** ** Suppose ./file1 and ./file2 are really the same file (because ** one is a hard or symbolic link to the other) then if you set ** an exclusive lock on fd1, then try to get an exclusive lock ** on fd2, it works. I would have expected the second lock to ** fail since there was already a lock on the file due to fd1. ** But not so. Since both locks came from the same process, the ** second overrides the first, even though they were on different ** file descriptors opened on different file names. ** ** Bummer. If you ask me, this is broken. Badly broken. It means ** that we cannot use POSIX locks to synchronize file access among ** competing threads of the same process. POSIX locks will work fine ** to synchronize access for threads in separate processes, but not ** threads within the same process. ** ** To work around the problem, SQLite has to manage file locks internally ** on its own. Whenever a new database is opened, we have to find the ** specific inode of the database file (the inode is determined by the ** st_dev and st_ino fields of the stat structure that fstat() fills in) ** and check for locks already existing on that inode. When locks are ** created or removed, we have to look at our own internal record of the ** locks to see if another thread has previously set a lock on that same ** inode. ** ** The sqlite3_file structure for POSIX is no longer just an integer file ** descriptor. It is now a structure that holds the integer file ** descriptor and a pointer to a structure that describes the internal ** locks on the corresponding inode. There is one locking structure ** per inode, so if the same inode is opened twice, both unixFile structures ** point to the same locking structure. The locking structure keeps ** a reference count (so we will know when to delete it) and a "cnt" ** field that tells us its internal lock status. cnt==0 means the ** file is unlocked. cnt==-1 means the file has an exclusive lock. ** cnt>0 means there are cnt shared locks on the file. ** ** Any attempt to lock or unlock a file first checks the locking ** structure. The fcntl() system call is only invoked to set a ** POSIX lock if the internal lock structure transitions between ** a locked and an unlocked state. ** ** 2004-Jan-11: ** More recent discoveries about POSIX advisory locks. (The more ** I discover, the more I realize the a POSIX advisory locks are ** an abomination.) ** ** If you close a file descriptor that points to a file that has locks, ** all locks on that file that are owned by the current process are ** released. To work around this problem, each unixFile structure contains ** a pointer to an openCnt structure. There is one openCnt structure ** per open inode, which means that multiple unixFile can point to a single ** openCnt. When an attempt is made to close an unixFile, if there are ** other unixFile open on the same inode that are holding locks, the call ** to close() the file descriptor is deferred until all of the locks clear. ** The openCnt structure keeps a list of file descriptors that need to ** be closed and that list is walked (and cleared) when the last lock ** clears. ** ** First, under Linux threads, because each thread has a separate ** process ID, lock operations in one thread do not override locks ** to the same file in other threads. Linux threads behave like ** separate processes in this respect. But, if you close a file ** descriptor in linux threads, all locks are cleared, even locks ** on other threads and even though the other threads have different ** process IDs. Linux threads is inconsistent in this respect. ** (I'm beginning to think that linux threads is an abomination too.) ** The consequence of this all is that the hash table for the lockInfo ** structure has to include the process id as part of its key because ** locks in different threads are treated as distinct. But the ** openCnt structure should not include the process id in its ** key because close() clears lock on all threads, not just the current ** thread. Were it not for this goofiness in linux threads, we could ** combine the lockInfo and openCnt structures into a single structure. ** ** 2004-Jun-28: ** On some versions of linux, threads can override each others locks. ** On others not. Sometimes you can change the behavior on the same ** system by setting the LD_ASSUME_KERNEL environment variable. The ** POSIX standard is silent as to which behavior is correct, as far ** as I can tell, so other versions of unix might show the same ** inconsistency. There is no little doubt in my mind that posix ** advisory locks and linux threads are profoundly broken. ** ** To work around the inconsistencies, we have to test at runtime ** whether or not threads can override each others locks. This test ** is run once, the first time any lock is attempted. A static ** variable is set to record the results of this test for future ** use. */ /* ** An instance of the following structure serves as the key used ** to locate a particular lockInfo structure given its inode. ** ** If threads cannot override each others locks, then we set the ** lockKey.tid field to the thread ID. If threads can override ** each others locks then tid is always set to zero. tid is omitted ** if we compile without threading support. */ struct lockKey { dev_t dev; /* Device number */ ino_t ino; /* Inode number */ #if SQLITE_THREADSAFE pthread_t tid; /* Thread ID or zero if threads can override each other */ #endif }; /* ** An instance of the following structure is allocated for each open ** inode on each thread with a different process ID. (Threads have ** different process IDs on linux, but not on most other unixes.) ** ** A single inode can have multiple file descriptors, so each unixFile ** structure contains a pointer to an instance of this object and this ** object keeps a count of the number of unixFile pointing to it. */ struct lockInfo { struct lockKey key; /* The lookup key */ int cnt; /* Number of SHARED locks held */ int locktype; /* One of SHARED_LOCK, RESERVED_LOCK etc. */ int nRef; /* Number of pointers to this structure */ struct lockInfo *pNext, *pPrev; /* List of all lockInfo objects */ }; /* ** An instance of the following structure serves as the key used ** to locate a particular openCnt structure given its inode. This ** is the same as the lockKey except that the thread ID is omitted. */ struct openKey { dev_t dev; /* Device number */ ino_t ino; /* Inode number */ }; /* ** An instance of the following structure is allocated for each open ** inode. This structure keeps track of the number of locks on that ** inode. If a close is attempted against an inode that is holding ** locks, the close is deferred until all locks clear by adding the ** file descriptor to be closed to the pending list. */ struct openCnt { struct openKey key; /* The lookup key */ int nRef; /* Number of pointers to this structure */ int nLock; /* Number of outstanding locks */ int nPending; /* Number of pending close() operations */ int *aPending; /* Malloced space holding fd's awaiting a close() */ struct openCnt *pNext, *pPrev; /* List of all openCnt objects */ }; /* ** List of all lockInfo and openCnt objects. This used to be a hash ** table. But the number of objects is rarely more than a dozen and ** never exceeds a few thousand. And lookup is not on a critical ** path oo a simple linked list will suffice. */ static struct lockInfo *lockList = 0; static struct openCnt *openList = 0; /* ** The locking styles are associated with the different file locking ** capabilities supported by different file systems. ** ** POSIX locking style fully supports shared and exclusive byte-range locks ** AFP locking only supports exclusive byte-range locks ** FLOCK only supports a single file-global exclusive lock ** DOTLOCK isn't a true locking style, it refers to the use of a special ** file named the same as the database file with a '.lock' extension, this ** can be used on file systems that do not offer any reliable file locking ** NO locking means that no locking will be attempted, this is only used for ** read-only file systems currently ** UNSUPPORTED means that no locking will be attempted, this is only used for ** file systems that are known to be unsupported */ #define LOCKING_STYLE_POSIX 1 #define LOCKING_STYLE_NONE 2 #define LOCKING_STYLE_DOTFILE 3 #define LOCKING_STYLE_FLOCK 4 #define LOCKING_STYLE_AFP 5 /* ** Only set the lastErrno if the error code is a real error and not ** a normal expected return code of SQLITE_BUSY or SQLITE_OK */ #define IS_LOCK_ERROR(x) ((x != SQLITE_OK) && (x != SQLITE_BUSY)) /* ** Helper functions to obtain and relinquish the global mutex. */ static void enterMutex(){ sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER)); } static void leaveMutex(){ sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER)); } #if SQLITE_THREADSAFE /* ** This variable records whether or not threads can override each others ** locks. ** ** 0: No. Threads cannot override each others locks. ** 1: Yes. Threads can override each others locks. ** -1: We don't know yet. ** ** On some systems, we know at compile-time if threads can override each ** others locks. On those systems, the SQLITE_THREAD_OVERRIDE_LOCK macro ** will be set appropriately. On other systems, we have to check at ** runtime. On these latter systems, SQLTIE_THREAD_OVERRIDE_LOCK is ** undefined. ** ** This variable normally has file scope only. But during testing, we make ** it a global so that the test code can change its value in order to verify ** that the right stuff happens in either case. */ #ifndef SQLITE_THREAD_OVERRIDE_LOCK # define SQLITE_THREAD_OVERRIDE_LOCK -1 #endif #ifdef SQLITE_TEST int threadsOverrideEachOthersLocks = SQLITE_THREAD_OVERRIDE_LOCK; #else static int threadsOverrideEachOthersLocks = SQLITE_THREAD_OVERRIDE_LOCK; #endif /* ** This structure holds information passed into individual test ** threads by the testThreadLockingBehavior() routine. */ struct threadTestData { int fd; /* File to be locked */ struct flock lock; /* The locking operation */ int result; /* Result of the locking operation */ }; #ifdef SQLITE_LOCK_TRACE /* ** Print out information about all locking operations. ** ** This routine is used for troubleshooting locks on multithreaded ** platforms. Enable by compiling with the -DSQLITE_LOCK_TRACE ** command-line option on the compiler. This code is normally ** turned off. */ static int lockTrace(int fd, int op, struct flock *p){ char *zOpName, *zType; int s; int savedErrno; if( op==F_GETLK ){ zOpName = "GETLK"; }else if( op==F_SETLK ){ zOpName = "SETLK"; }else{ s = fcntl(fd, op, p); sqlite3DebugPrintf("fcntl unknown %d %d %d\n", fd, op, s); return s; } if( p->l_type==F_RDLCK ){ zType = "RDLCK"; }else if( p->l_type==F_WRLCK ){ zType = "WRLCK"; }else if( p->l_type==F_UNLCK ){ zType = "UNLCK"; }else{ assert( 0 ); } assert( p->l_whence==SEEK_SET ); s = fcntl(fd, op, p); savedErrno = errno; sqlite3DebugPrintf("fcntl %d %d %s %s %d %d %d %d\n", threadid, fd, zOpName, zType, (int)p->l_start, (int)p->l_len, (int)p->l_pid, s); if( s==(-1) && op==F_SETLK && (p->l_type==F_RDLCK || p->l_type==F_WRLCK) ){ struct flock l2; l2 = *p; fcntl(fd, F_GETLK, &l2); if( l2.l_type==F_RDLCK ){ zType = "RDLCK"; }else if( l2.l_type==F_WRLCK ){ zType = "WRLCK"; }else if( l2.l_type==F_UNLCK ){ zType = "UNLCK"; }else{ assert( 0 ); } sqlite3DebugPrintf("fcntl-failure-reason: %s %d %d %d\n", zType, (int)l2.l_start, (int)l2.l_len, (int)l2.l_pid); } errno = savedErrno; return s; } #define fcntl lockTrace #endif /* SQLITE_LOCK_TRACE */ /* ** The testThreadLockingBehavior() routine launches two separate ** threads on this routine. This routine attempts to lock a file ** descriptor then returns. The success or failure of that attempt ** allows the testThreadLockingBehavior() procedure to determine ** whether or not threads can override each others locks. */ static void *threadLockingTest(void *pArg){ struct threadTestData *pData = (struct threadTestData*)pArg; pData->result = fcntl(pData->fd, F_SETLK, &pData->lock); return pArg; } /* ** This procedure attempts to determine whether or not threads ** can override each others locks then sets the ** threadsOverrideEachOthersLocks variable appropriately. */ static void testThreadLockingBehavior(int fd_orig){ int fd; struct threadTestData d[2]; pthread_t t[2]; fd = dup(fd_orig); if( fd<0 ) return; memset(d, 0, sizeof(d)); d[0].fd = fd; d[0].lock.l_type = F_RDLCK; d[0].lock.l_len = 1; d[0].lock.l_start = 0; d[0].lock.l_whence = SEEK_SET; d[1] = d[0]; d[1].lock.l_type = F_WRLCK; pthread_create(&t[0], 0, threadLockingTest, &d[0]); pthread_create(&t[1], 0, threadLockingTest, &d[1]); pthread_join(t[0], 0); pthread_join(t[1], 0); close(fd); threadsOverrideEachOthersLocks = d[0].result==0 && d[1].result==0; } #endif /* SQLITE_THREADSAFE */ /* ** Release a lockInfo structure previously allocated by findLockInfo(). */ static void releaseLockInfo(struct lockInfo *pLock){ if( pLock ){ pLock->nRef--; if( pLock->nRef==0 ){ if( pLock->pPrev ){ assert( pLock->pPrev->pNext==pLock ); pLock->pPrev->pNext = pLock->pNext; }else{ assert( lockList==pLock ); lockList = pLock->pNext; } if( pLock->pNext ){ assert( pLock->pNext->pPrev==pLock ); pLock->pNext->pPrev = pLock->pPrev; } sqlite3_free(pLock); } } } /* ** Release a openCnt structure previously allocated by findLockInfo(). */ static void releaseOpenCnt(struct openCnt *pOpen){ if( pOpen ){ pOpen->nRef--; if( pOpen->nRef==0 ){ if( pOpen->pPrev ){ assert( pOpen->pPrev->pNext==pOpen ); pOpen->pPrev->pNext = pOpen->pNext; }else{ assert( openList==pOpen ); openList = pOpen->pNext; } if( pOpen->pNext ){ assert( pOpen->pNext->pPrev==pOpen ); pOpen->pNext->pPrev = pOpen->pPrev; } sqlite3_free(pOpen->aPending); sqlite3_free(pOpen); } } } #if SQLITE_ENABLE_LOCKING_STYLE /* ** Tests a byte-range locking query to see if byte range locks are ** supported, if not we fall back to dotlockLockingStyle. */ static int testLockingStyle(int fd){ struct flock lockInfo; /* Test byte-range lock using fcntl(). If the call succeeds, ** assume that the file-system supports POSIX style locks. */ lockInfo.l_len = 1; lockInfo.l_start = 0; lockInfo.l_whence = SEEK_SET; lockInfo.l_type = F_RDLCK; if( fcntl(fd, F_GETLK, &lockInfo)!=-1 ) { return LOCKING_STYLE_POSIX; } /* Testing for flock() can give false positives. So if if the above ** test fails, then we fall back to using dot-file style locking. */ return LOCKING_STYLE_DOTFILE; } #endif /* ** If SQLITE_ENABLE_LOCKING_STYLE is defined, this function Examines the ** f_fstypename entry in the statfs structure as returned by stat() for ** the file system hosting the database file and selects the appropriate ** locking style based on its value. These values and assignments are ** based on Darwin/OSX behavior and have not been thoroughly tested on ** other systems. ** ** If SQLITE_ENABLE_LOCKING_STYLE is not defined, this function always ** returns LOCKING_STYLE_POSIX. */ static int detectLockingStyle( sqlite3_vfs *pVfs, const char *filePath, int fd ){ #if SQLITE_ENABLE_LOCKING_STYLE struct Mapping { const char *zFilesystem; int eLockingStyle; } aMap[] = { { "hfs", LOCKING_STYLE_POSIX }, { "ufs", LOCKING_STYLE_POSIX }, { "afpfs", LOCKING_STYLE_AFP }, #ifdef SQLITE_ENABLE_AFP_LOCKING_SMB { "smbfs", LOCKING_STYLE_AFP }, #else { "smbfs", LOCKING_STYLE_FLOCK }, #endif { "msdos", LOCKING_STYLE_DOTFILE }, { "webdav", LOCKING_STYLE_NONE }, { 0, 0 } }; int i; struct statfs fsInfo; if( !filePath ){ return LOCKING_STYLE_NONE; } if( pVfs->pAppData ){ return SQLITE_PTR_TO_INT(pVfs->pAppData); } if( statfs(filePath, &fsInfo) != -1 ){ if( fsInfo.f_flags & MNT_RDONLY ){ return LOCKING_STYLE_NONE; } for(i=0; aMap[i].zFilesystem; i++){ if( strcmp(fsInfo.f_fstypename, aMap[i].zFilesystem)==0 ){ return aMap[i].eLockingStyle; } } } /* Default case. Handles, amongst others, "nfs". */ return testLockingStyle(fd); #endif return LOCKING_STYLE_POSIX; } /* ** Given a file descriptor, locate lockInfo and openCnt structures that ** describes that file descriptor. Create new ones if necessary. The ** return values might be uninitialized if an error occurs. ** ** Return an appropriate error code. */ static int findLockInfo( int fd, /* The file descriptor used in the key */ struct lockInfo **ppLock, /* Return the lockInfo structure here */ struct openCnt **ppOpen /* Return the openCnt structure here */ ){ int rc; struct lockKey key1; struct openKey key2; struct stat statbuf; struct lockInfo *pLock; struct openCnt *pOpen; rc = fstat(fd, &statbuf); if( rc!=0 ){ #ifdef EOVERFLOW if( errno==EOVERFLOW ) return SQLITE_NOLFS; #endif return SQLITE_IOERR; } /* On OS X on an msdos filesystem, the inode number is reported ** incorrectly for zero-size files. See ticket #3260. To work ** around this problem (we consider it a bug in OS X, not SQLite) ** we always increase the file size to 1 by writing a single byte ** prior to accessing the inode number. The one byte written is ** an ASCII 'S' character which also happens to be the first byte ** in the header of every SQLite database. In this way, if there ** is a race condition such that another thread has already populated ** the first page of the database, no damage is done. */ if( statbuf.st_size==0 ){ write(fd, "S", 1); rc = fstat(fd, &statbuf); if( rc!=0 ){ return SQLITE_IOERR; } } memset(&key1, 0, sizeof(key1)); key1.dev = statbuf.st_dev; key1.ino = statbuf.st_ino; #if SQLITE_THREADSAFE if( threadsOverrideEachOthersLocks<0 ){ testThreadLockingBehavior(fd); } key1.tid = threadsOverrideEachOthersLocks ? 0 : pthread_self(); #endif memset(&key2, 0, sizeof(key2)); key2.dev = statbuf.st_dev; key2.ino = statbuf.st_ino; pLock = lockList; while( pLock && memcmp(&key1, &pLock->key, sizeof(key1)) ){ pLock = pLock->pNext; } if( pLock==0 ){ pLock = sqlite3_malloc( sizeof(*pLock) ); if( pLock==0 ){ rc = SQLITE_NOMEM; goto exit_findlockinfo; } pLock->key = key1; pLock->nRef = 1; pLock->cnt = 0; pLock->locktype = 0; pLock->pNext = lockList; pLock->pPrev = 0; if( lockList ) lockList->pPrev = pLock; lockList = pLock; }else{ pLock->nRef++; } *ppLock = pLock; if( ppOpen!=0 ){ pOpen = openList; while( pOpen && memcmp(&key2, &pOpen->key, sizeof(key2)) ){ pOpen = pOpen->pNext; } if( pOpen==0 ){ pOpen = sqlite3_malloc( sizeof(*pOpen) ); if( pOpen==0 ){ releaseLockInfo(pLock); rc = SQLITE_NOMEM; goto exit_findlockinfo; } pOpen->key = key2; pOpen->nRef = 1; pOpen->nLock = 0; pOpen->nPending = 0; pOpen->aPending = 0; pOpen->pNext = openList; pOpen->pPrev = 0; if( openList ) openList->pPrev = pOpen; openList = pOpen; }else{ pOpen->nRef++; } *ppOpen = pOpen; } exit_findlockinfo: return rc; } #ifdef SQLITE_DEBUG /* ** Helper function for printing out trace information from debugging ** binaries. This returns the string represetation of the supplied ** integer lock-type. */ static const char *locktypeName(int locktype){ switch( locktype ){ case NO_LOCK: return "NONE"; case SHARED_LOCK: return "SHARED"; case RESERVED_LOCK: return "RESERVED"; case PENDING_LOCK: return "PENDING"; case EXCLUSIVE_LOCK: return "EXCLUSIVE"; } return "ERROR"; } #endif /* ** If we are currently in a different thread than the thread that the ** unixFile argument belongs to, then transfer ownership of the unixFile ** over to the current thread. ** ** A unixFile is only owned by a thread on systems where one thread is ** unable to override locks created by a different thread. RedHat9 is ** an example of such a system. ** ** Ownership transfer is only allowed if the unixFile is currently unlocked. ** If the unixFile is locked and an ownership is wrong, then return ** SQLITE_MISUSE. SQLITE_OK is returned if everything works. */ #if SQLITE_THREADSAFE static int transferOwnership(unixFile *pFile){ int rc; pthread_t hSelf; if( threadsOverrideEachOthersLocks ){ /* Ownership transfers not needed on this system */ return SQLITE_OK; } hSelf = pthread_self(); if( pthread_equal(pFile->tid, hSelf) ){ /* We are still in the same thread */ OSTRACE1("No-transfer, same thread\n"); return SQLITE_OK; } if( pFile->locktype!=NO_LOCK ){ /* We cannot change ownership while we are holding a lock! */ return SQLITE_MISUSE; } OSTRACE4("Transfer ownership of %d from %d to %d\n", pFile->h, pFile->tid, hSelf); pFile->tid = hSelf; if (pFile->pLock != NULL) { releaseLockInfo(pFile->pLock); rc = findLockInfo(pFile->h, &pFile->pLock, 0); OSTRACE5("LOCK %d is now %s(%s,%d)\n", pFile->h, locktypeName(pFile->locktype), locktypeName(pFile->pLock->locktype), pFile->pLock->cnt); return rc; } else { return SQLITE_OK; } } #else /* On single-threaded builds, ownership transfer is a no-op */ # define transferOwnership(X) SQLITE_OK #endif /* ** Seek to the offset passed as the second argument, then read cnt ** bytes into pBuf. Return the number of bytes actually read. ** ** NB: If you define USE_PREAD or USE_PREAD64, then it might also ** be necessary to define _XOPEN_SOURCE to be 500. This varies from ** one system to another. Since SQLite does not define USE_PREAD ** any any form by default, we will not attempt to define _XOPEN_SOURCE. ** See tickets #2741 and #2681. */ static int seekAndRead(unixFile *id, sqlite3_int64 offset, void *pBuf, int cnt){ int got; i64 newOffset; TIMER_START; #if defined(USE_PREAD) got = pread(id->h, pBuf, cnt, offset); SimulateIOError( got = -1 ); #elif defined(USE_PREAD64) got = pread64(id->h, pBuf, cnt, offset); SimulateIOError( got = -1 ); #else newOffset = lseek(id->h, offset, SEEK_SET); SimulateIOError( newOffset-- ); if( newOffset!=offset ){ return -1; } got = read(id->h, pBuf, cnt); #endif TIMER_END; OSTRACE5("READ %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED); return got; } /* ** Read data from a file into a buffer. Return SQLITE_OK if all ** bytes were read successfully and SQLITE_IOERR if anything goes ** wrong. */ static int unixRead( sqlite3_file *id, void *pBuf, int amt, sqlite3_int64 offset ){ int got; assert( id ); got = seekAndRead((unixFile*)id, offset, pBuf, amt); if( got==amt ){ return SQLITE_OK; }else if( got<0 ){ return SQLITE_IOERR_READ; }else{ memset(&((char*)pBuf)[got], 0, amt-got); return SQLITE_IOERR_SHORT_READ; } } /* ** Seek to the offset in id->offset then read cnt bytes into pBuf. ** Return the number of bytes actually read. Update the offset. */ static int seekAndWrite(unixFile *id, i64 offset, const void *pBuf, int cnt){ int got; i64 newOffset; TIMER_START; #if defined(USE_PREAD) got = pwrite(id->h, pBuf, cnt, offset); #elif defined(USE_PREAD64) got = pwrite64(id->h, pBuf, cnt, offset); #else newOffset = lseek(id->h, offset, SEEK_SET); if( newOffset!=offset ){ return -1; } got = write(id->h, pBuf, cnt); #endif TIMER_END; OSTRACE5("WRITE %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED); return got; } /* ** Write data from a buffer into a file. Return SQLITE_OK on success ** or some other error code on failure. */ static int unixWrite( sqlite3_file *id, const void *pBuf, int amt, sqlite3_int64 offset ){ int wrote = 0; assert( id ); assert( amt>0 ); while( amt>0 && (wrote = seekAndWrite((unixFile*)id, offset, pBuf, amt))>0 ){ amt -= wrote; offset += wrote; pBuf = &((char*)pBuf)[wrote]; } SimulateIOError(( wrote=(-1), amt=1 )); SimulateDiskfullError(( wrote=0, amt=1 )); if( amt>0 ){ if( wrote<0 ){ return SQLITE_IOERR_WRITE; }else{ return SQLITE_FULL; } } return SQLITE_OK; } #ifdef SQLITE_TEST /* ** Count the number of fullsyncs and normal syncs. This is used to test ** that syncs and fullsyncs are occuring at the right times. */ int sqlite3_sync_count = 0; int sqlite3_fullsync_count = 0; #endif /* ** Use the fdatasync() API only if the HAVE_FDATASYNC macro is defined. ** Otherwise use fsync() in its place. */ #ifndef HAVE_FDATASYNC # define fdatasync fsync #endif /* ** Define HAVE_FULLFSYNC to 0 or 1 depending on whether or not ** the F_FULLFSYNC macro is defined. F_FULLFSYNC is currently ** only available on Mac OS X. But that could change. */ #ifdef F_FULLFSYNC # define HAVE_FULLFSYNC 1 #else # define HAVE_FULLFSYNC 0 #endif /* ** The fsync() system call does not work as advertised on many ** unix systems. The following procedure is an attempt to make ** it work better. ** ** The SQLITE_NO_SYNC macro disables all fsync()s. This is useful ** for testing when we want to run through the test suite quickly. ** You are strongly advised *not* to deploy with SQLITE_NO_SYNC ** enabled, however, since with SQLITE_NO_SYNC enabled, an OS crash ** or power failure will likely corrupt the database file. */ static int full_fsync(int fd, int fullSync, int dataOnly){ int rc; /* Record the number of times that we do a normal fsync() and ** FULLSYNC. This is used during testing to verify that this procedure ** gets called with the correct arguments. */ #ifdef SQLITE_TEST if( fullSync ) sqlite3_fullsync_count++; sqlite3_sync_count++; #endif /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a ** no-op */ #ifdef SQLITE_NO_SYNC rc = SQLITE_OK; #else #if HAVE_FULLFSYNC if( fullSync ){ rc = fcntl(fd, F_FULLFSYNC, 0); }else{ rc = 1; } /* If the FULLFSYNC failed, fall back to attempting an fsync(). * It shouldn't be possible for fullfsync to fail on the local * file system (on OSX), so failure indicates that FULLFSYNC * isn't supported for this file system. So, attempt an fsync * and (for now) ignore the overhead of a superfluous fcntl call. * It'd be better to detect fullfsync support once and avoid * the fcntl call every time sync is called. */ if( rc ) rc = fsync(fd); #else if( dataOnly ){ rc = fdatasync(fd); }else{ rc = fsync(fd); } #endif /* HAVE_FULLFSYNC */ #endif /* defined(SQLITE_NO_SYNC) */ return rc; } /* ** Make sure all writes to a particular file are committed to disk. ** ** If dataOnly==0 then both the file itself and its metadata (file ** size, access time, etc) are synced. If dataOnly!=0 then only the ** file data is synced. ** ** Under Unix, also make sure that the directory entry for the file ** has been created by fsync-ing the directory that contains the file. ** If we do not do this and we encounter a power failure, the directory ** entry for the journal might not exist after we reboot. The next ** SQLite to access the file will not know that the journal exists (because ** the directory entry for the journal was never created) and the transaction ** will not roll back - possibly leading to database corruption. */ static int unixSync(sqlite3_file *id, int flags){ int rc; unixFile *pFile = (unixFile*)id; int isDataOnly = (flags&SQLITE_SYNC_DATAONLY); int isFullsync = (flags&0x0F)==SQLITE_SYNC_FULL; /* Check that one of SQLITE_SYNC_NORMAL or FULL was passed */ assert((flags&0x0F)==SQLITE_SYNC_NORMAL || (flags&0x0F)==SQLITE_SYNC_FULL ); /* Unix cannot, but some systems may return SQLITE_FULL from here. This ** line is to test that doing so does not cause any problems. */ SimulateDiskfullError( return SQLITE_FULL ); assert( pFile ); OSTRACE2("SYNC %-3d\n", pFile->h); rc = full_fsync(pFile->h, isFullsync, isDataOnly); SimulateIOError( rc=1 ); if( rc ){ return SQLITE_IOERR_FSYNC; } if( pFile->dirfd>=0 ){ OSTRACE4("DIRSYNC %-3d (have_fullfsync=%d fullsync=%d)\n", pFile->dirfd, HAVE_FULLFSYNC, isFullsync); #ifndef SQLITE_DISABLE_DIRSYNC /* The directory sync is only attempted if full_fsync is ** turned off or unavailable. If a full_fsync occurred above, ** then the directory sync is superfluous. */ if( (!HAVE_FULLFSYNC || !isFullsync) && full_fsync(pFile->dirfd,0,0) ){ /* ** We have received multiple reports of fsync() returning ** errors when applied to directories on certain file systems. ** A failed directory sync is not a big deal. So it seems ** better to ignore the error. Ticket #1657 */ /* return SQLITE_IOERR; */ } #endif close(pFile->dirfd); /* Only need to sync once, so close the directory */ pFile->dirfd = -1; /* when we are done. */ } return SQLITE_OK; } /* ** Truncate an open file to a specified size */ static int unixTruncate(sqlite3_file *id, i64 nByte){ int rc; assert( id ); SimulateIOError( return SQLITE_IOERR_TRUNCATE ); rc = ftruncate(((unixFile*)id)->h, (off_t)nByte); if( rc ){ return SQLITE_IOERR_TRUNCATE; }else{ return SQLITE_OK; } } /* ** Determine the current size of a file in bytes */ static int unixFileSize(sqlite3_file *id, i64 *pSize){ int rc; struct stat buf; assert( id ); rc = fstat(((unixFile*)id)->h, &buf); SimulateIOError( rc=1 ); if( rc!=0 ){ return SQLITE_IOERR_FSTAT; } *pSize = buf.st_size; /* When opening a zero-size database, the findLockInfo() procedure ** writes a single byte into that file in order to work around a bug ** in the OS-X msdos filesystem. In order to avoid problems with upper ** layers, we need to report this file size as zero even though it is ** really 1. Ticket #3260. */ if( *pSize==1 ) *pSize = 0; return SQLITE_OK; } /* ** This routine translates a standard POSIX errno code into something ** useful to the clients of the sqlite3 functions. Specifically, it is ** intended to translate a variety of "try again" errors into SQLITE_BUSY ** and a variety of "please close the file descriptor NOW" errors into ** SQLITE_IOERR ** ** Errors during initialization of locks, or file system support for locks, ** should handle ENOLCK, ENOTSUP, EOPNOTSUPP separately. */ static int sqliteErrorFromPosixError(int posixError, int sqliteIOErr) { switch (posixError) { case 0: return SQLITE_OK; case EAGAIN: case ETIMEDOUT: case EBUSY: case EINTR: case ENOLCK: /* random NFS retry error, unless during file system support * introspection, in which it actually means what it says */ return SQLITE_BUSY; case EACCES: /* EACCES is like EAGAIN during locking operations, but not any other time*/ if( (sqliteIOErr == SQLITE_IOERR_LOCK) || (sqliteIOErr == SQLITE_IOERR_UNLOCK) || (sqliteIOErr == SQLITE_IOERR_RDLOCK) || (sqliteIOErr == SQLITE_IOERR_CHECKRESERVEDLOCK) ){ return SQLITE_BUSY; } /* else fall through */ case EPERM: return SQLITE_PERM; case EDEADLK: return SQLITE_IOERR_BLOCKED; #if EOPNOTSUPP!=ENOTSUP case EOPNOTSUPP: /* something went terribly awry, unless during file system support * introspection, in which it actually means what it says */ #endif #ifdef ENOTSUP case ENOTSUP: /* invalid fd, unless during file system support introspection, in which * it actually means what it says */ #endif case EIO: case EBADF: case EINVAL: case ENOTCONN: case ENODEV: case ENXIO: case ENOENT: case ESTALE: case ENOSYS: /* these should force the client to close the file and reconnect */ default: return sqliteIOErr; } } /* ** This routine checks if there is a RESERVED lock held on the specified ** file by this or any other process. If such a lock is held, set *pResOut ** to a non-zero value otherwise *pResOut is set to zero. The return value ** is set to SQLITE_OK unless an I/O error occurs during lock checking. */ static int unixCheckReservedLock(sqlite3_file *id, int *pResOut){ int rc = SQLITE_OK; int reserved = 0; unixFile *pFile = (unixFile*)id; SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; ); assert( pFile ); enterMutex(); /* Because pFile->pLock is shared across threads */ /* Check if a thread in this process holds such a lock */ if( pFile->pLock->locktype>SHARED_LOCK ){ reserved = 1; } /* Otherwise see if some other process holds it. */ if( !reserved ){ struct flock lock; lock.l_whence = SEEK_SET; lock.l_start = RESERVED_BYTE; lock.l_len = 1; lock.l_type = F_WRLCK; if (-1 == fcntl(pFile->h, F_GETLK, &lock)) { int tErrno = errno; rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK); pFile->lastErrno = tErrno; } else if( lock.l_type!=F_UNLCK ){ reserved = 1; } } leaveMutex(); OSTRACE4("TEST WR-LOCK %d %d %d\n", pFile->h, rc, reserved); *pResOut = reserved; return rc; } /* ** Lock the file with the lock specified by parameter locktype - one ** of the following: ** ** (1) SHARED_LOCK ** (2) RESERVED_LOCK ** (3) PENDING_LOCK ** (4) EXCLUSIVE_LOCK ** ** Sometimes when requesting one lock state, additional lock states ** are inserted in between. The locking might fail on one of the later ** transitions leaving the lock state different from what it started but ** still short of its goal. The following chart shows the allowed ** transitions and the inserted intermediate states: ** ** UNLOCKED -> SHARED ** SHARED -> RESERVED ** SHARED -> (PENDING) -> EXCLUSIVE ** RESERVED -> (PENDING) -> EXCLUSIVE ** PENDING -> EXCLUSIVE ** ** This routine will only increase a lock. Use the sqlite3OsUnlock() ** routine to lower a locking level. */ static int unixLock(sqlite3_file *id, int locktype){ /* The following describes the implementation of the various locks and ** lock transitions in terms of the POSIX advisory shared and exclusive ** lock primitives (called read-locks and write-locks below, to avoid ** confusion with SQLite lock names). The algorithms are complicated ** slightly in order to be compatible with windows systems simultaneously ** accessing the same database file, in case that is ever required. ** ** Symbols defined in os.h indentify the 'pending byte' and the 'reserved ** byte', each single bytes at well known offsets, and the 'shared byte ** range', a range of 510 bytes at a well known offset. ** ** To obtain a SHARED lock, a read-lock is obtained on the 'pending ** byte'. If this is successful, a random byte from the 'shared byte ** range' is read-locked and the lock on the 'pending byte' released. ** ** A process may only obtain a RESERVED lock after it has a SHARED lock. ** A RESERVED lock is implemented by grabbing a write-lock on the ** 'reserved byte'. ** ** A process may only obtain a PENDING lock after it has obtained a ** SHARED lock. A PENDING lock is implemented by obtaining a write-lock ** on the 'pending byte'. This ensures that no new SHARED locks can be ** obtained, but existing SHARED locks are allowed to persist. A process ** does not have to obtain a RESERVED lock on the way to a PENDING lock. ** This property is used by the algorithm for rolling back a journal file ** after a crash. ** ** An EXCLUSIVE lock, obtained after a PENDING lock is held, is ** implemented by obtaining a write-lock on the entire 'shared byte ** range'. Since all other locks require a read-lock on one of the bytes ** within this range, this ensures that no other locks are held on the ** database. ** ** The reason a single byte cannot be used instead of the 'shared byte ** range' is that some versions of windows do not support read-locks. By ** locking a random byte from a range, concurrent SHARED locks may exist ** even if the locking primitive used is always a write-lock. */ int rc = SQLITE_OK; unixFile *pFile = (unixFile*)id; struct lockInfo *pLock = pFile->pLock; struct flock lock; int s; assert( pFile ); OSTRACE7("LOCK %d %s was %s(%s,%d) pid=%d\n", pFile->h, locktypeName(locktype), locktypeName(pFile->locktype), locktypeName(pLock->locktype), pLock->cnt , getpid()); /* If there is already a lock of this type or more restrictive on the ** unixFile, do nothing. Don't use the end_lock: exit path, as ** enterMutex() hasn't been called yet. */ if( pFile->locktype>=locktype ){ OSTRACE3("LOCK %d %s ok (already held)\n", pFile->h, locktypeName(locktype)); return SQLITE_OK; } /* Make sure the locking sequence is correct */ assert( pFile->locktype!=NO_LOCK || locktype==SHARED_LOCK ); assert( locktype!=PENDING_LOCK ); assert( locktype!=RESERVED_LOCK || pFile->locktype==SHARED_LOCK ); /* This mutex is needed because pFile->pLock is shared across threads */ enterMutex(); /* Make sure the current thread owns the pFile. */ rc = transferOwnership(pFile); if( rc!=SQLITE_OK ){ leaveMutex(); return rc; } pLock = pFile->pLock; /* If some thread using this PID has a lock via a different unixFile* ** handle that precludes the requested lock, return BUSY. */ if( (pFile->locktype!=pLock->locktype && (pLock->locktype>=PENDING_LOCK || locktype>SHARED_LOCK)) ){ rc = SQLITE_BUSY; goto end_lock; } /* If a SHARED lock is requested, and some thread using this PID already ** has a SHARED or RESERVED lock, then increment reference counts and ** return SQLITE_OK. */ if( locktype==SHARED_LOCK && (pLock->locktype==SHARED_LOCK || pLock->locktype==RESERVED_LOCK) ){ assert( locktype==SHARED_LOCK ); assert( pFile->locktype==0 ); assert( pLock->cnt>0 ); pFile->locktype = SHARED_LOCK; pLock->cnt++; pFile->pOpen->nLock++; goto end_lock; } lock.l_len = 1L; lock.l_whence = SEEK_SET; /* A PENDING lock is needed before acquiring a SHARED lock and before ** acquiring an EXCLUSIVE lock. For the SHARED lock, the PENDING will ** be released. */ if( locktype==SHARED_LOCK || (locktype==EXCLUSIVE_LOCK && pFile->locktypeh, F_SETLK, &lock); if( s==(-1) ){ int tErrno = errno; rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK); if( IS_LOCK_ERROR(rc) ){ pFile->lastErrno = tErrno; } goto end_lock; } } /* If control gets to this point, then actually go ahead and make ** operating system calls for the specified lock. */ if( locktype==SHARED_LOCK ){ int tErrno = 0; assert( pLock->cnt==0 ); assert( pLock->locktype==0 ); /* Now get the read-lock */ lock.l_start = SHARED_FIRST; lock.l_len = SHARED_SIZE; if( (s = fcntl(pFile->h, F_SETLK, &lock))==(-1) ){ tErrno = errno; } /* Drop the temporary PENDING lock */ lock.l_start = PENDING_BYTE; lock.l_len = 1L; lock.l_type = F_UNLCK; if( fcntl(pFile->h, F_SETLK, &lock)!=0 ){ if( s != -1 ){ /* This could happen with a network mount */ tErrno = errno; rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK); if( IS_LOCK_ERROR(rc) ){ pFile->lastErrno = tErrno; } goto end_lock; } } if( s==(-1) ){ rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK); if( IS_LOCK_ERROR(rc) ){ pFile->lastErrno = tErrno; } }else{ pFile->locktype = SHARED_LOCK; pFile->pOpen->nLock++; pLock->cnt = 1; } }else if( locktype==EXCLUSIVE_LOCK && pLock->cnt>1 ){ /* We are trying for an exclusive lock but another thread in this ** same process is still holding a shared lock. */ rc = SQLITE_BUSY; }else{ /* The request was for a RESERVED or EXCLUSIVE lock. It is ** assumed that there is a SHARED or greater lock on the file ** already. */ assert( 0!=pFile->locktype ); lock.l_type = F_WRLCK; switch( locktype ){ case RESERVED_LOCK: lock.l_start = RESERVED_BYTE; break; case EXCLUSIVE_LOCK: lock.l_start = SHARED_FIRST; lock.l_len = SHARED_SIZE; break; default: assert(0); } s = fcntl(pFile->h, F_SETLK, &lock); if( s==(-1) ){ int tErrno = errno; rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK); if( IS_LOCK_ERROR(rc) ){ pFile->lastErrno = tErrno; } } } if( rc==SQLITE_OK ){ pFile->locktype = locktype; pLock->locktype = locktype; }else if( locktype==EXCLUSIVE_LOCK ){ pFile->locktype = PENDING_LOCK; pLock->locktype = PENDING_LOCK; } end_lock: leaveMutex(); OSTRACE4("LOCK %d %s %s\n", pFile->h, locktypeName(locktype), rc==SQLITE_OK ? "ok" : "failed"); return rc; } /* ** Lower the locking level on file descriptor pFile to locktype. locktype ** must be either NO_LOCK or SHARED_LOCK. ** ** If the locking level of the file descriptor is already at or below ** the requested locking level, this routine is a no-op. */ static int unixUnlock(sqlite3_file *id, int locktype){ struct lockInfo *pLock; struct flock lock; int rc = SQLITE_OK; unixFile *pFile = (unixFile*)id; int h; assert( pFile ); OSTRACE7("UNLOCK %d %d was %d(%d,%d) pid=%d\n", pFile->h, locktype, pFile->locktype, pFile->pLock->locktype, pFile->pLock->cnt, getpid()); assert( locktype<=SHARED_LOCK ); if( pFile->locktype<=locktype ){ return SQLITE_OK; } if( CHECK_THREADID(pFile) ){ return SQLITE_MISUSE; } enterMutex(); h = pFile->h; pLock = pFile->pLock; assert( pLock->cnt!=0 ); if( pFile->locktype>SHARED_LOCK ){ assert( pLock->locktype==pFile->locktype ); SimulateIOErrorBenign(1); SimulateIOError( h=(-1) ) SimulateIOErrorBenign(0); if( locktype==SHARED_LOCK ){ lock.l_type = F_RDLCK; lock.l_whence = SEEK_SET; lock.l_start = SHARED_FIRST; lock.l_len = SHARED_SIZE; if( fcntl(h, F_SETLK, &lock)==(-1) ){ int tErrno = errno; rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK); if( IS_LOCK_ERROR(rc) ){ pFile->lastErrno = tErrno; } goto end_unlock; } } lock.l_type = F_UNLCK; lock.l_whence = SEEK_SET; lock.l_start = PENDING_BYTE; lock.l_len = 2L; assert( PENDING_BYTE+1==RESERVED_BYTE ); if( fcntl(h, F_SETLK, &lock)!=(-1) ){ pLock->locktype = SHARED_LOCK; }else{ int tErrno = errno; rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK); if( IS_LOCK_ERROR(rc) ){ pFile->lastErrno = tErrno; } goto end_unlock; } } if( locktype==NO_LOCK ){ struct openCnt *pOpen; /* Decrement the shared lock counter. Release the lock using an ** OS call only when all threads in this same process have released ** the lock. */ pLock->cnt--; if( pLock->cnt==0 ){ lock.l_type = F_UNLCK; lock.l_whence = SEEK_SET; lock.l_start = lock.l_len = 0L; SimulateIOErrorBenign(1); SimulateIOError( h=(-1) ) SimulateIOErrorBenign(0); if( fcntl(h, F_SETLK, &lock)!=(-1) ){ pLock->locktype = NO_LOCK; }else{ int tErrno = errno; rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK); if( IS_LOCK_ERROR(rc) ){ pFile->lastErrno = tErrno; } pLock->cnt = 1; goto end_unlock; } } /* Decrement the count of locks against this same file. When the ** count reaches zero, close any other file descriptors whose close ** was deferred because of outstanding locks. */ if( rc==SQLITE_OK ){ pOpen = pFile->pOpen; pOpen->nLock--; assert( pOpen->nLock>=0 ); if( pOpen->nLock==0 && pOpen->nPending>0 ){ int i; for(i=0; inPending; i++){ close(pOpen->aPending[i]); } sqlite3_free(pOpen->aPending); pOpen->nPending = 0; pOpen->aPending = 0; } } } end_unlock: leaveMutex(); if( rc==SQLITE_OK ) pFile->locktype = locktype; return rc; } /* ** This function performs the parts of the "close file" operation ** common to all locking schemes. It closes the directory and file ** handles, if they are valid, and sets all fields of the unixFile ** structure to 0. */ static int closeUnixFile(sqlite3_file *id){ unixFile *pFile = (unixFile*)id; if( pFile ){ if( pFile->dirfd>=0 ){ close(pFile->dirfd); } if( pFile->h>=0 ){ close(pFile->h); } OSTRACE2("CLOSE %-3d\n", pFile->h); OpenCounter(-1); memset(pFile, 0, sizeof(unixFile)); } return SQLITE_OK; } /* ** Close a file. */ static int unixClose(sqlite3_file *id){ if( id ){ unixFile *pFile = (unixFile *)id; unixUnlock(id, NO_LOCK); enterMutex(); if( pFile->pOpen && pFile->pOpen->nLock ){ /* If there are outstanding locks, do not actually close the file just ** yet because that would clear those locks. Instead, add the file ** descriptor to pOpen->aPending. It will be automatically closed when ** the last lock is cleared. */ int *aNew; struct openCnt *pOpen = pFile->pOpen; aNew = sqlite3_realloc(pOpen->aPending, (pOpen->nPending+1)*sizeof(int) ); if( aNew==0 ){ /* If a malloc fails, just leak the file descriptor */ }else{ pOpen->aPending = aNew; pOpen->aPending[pOpen->nPending] = pFile->h; pOpen->nPending++; pFile->h = -1; } } releaseLockInfo(pFile->pLock); releaseOpenCnt(pFile->pOpen); closeUnixFile(id); leaveMutex(); } return SQLITE_OK; } #if SQLITE_ENABLE_LOCKING_STYLE #pragma mark AFP Support /* ** The afpLockingContext structure contains all afp lock specific state */ typedef struct afpLockingContext afpLockingContext; struct afpLockingContext { unsigned long long sharedLockByte; const char *filePath; }; struct ByteRangeLockPB2 { unsigned long long offset; /* offset to first byte to lock */ unsigned long long length; /* nbr of bytes to lock */ unsigned long long retRangeStart; /* nbr of 1st byte locked if successful */ unsigned char unLockFlag; /* 1 = unlock, 0 = lock */ unsigned char startEndFlag; /* 1=rel to end of fork, 0=rel to start */ int fd; /* file desc to assoc this lock with */ }; #define afpfsByteRangeLock2FSCTL _IOWR('z', 23, struct ByteRangeLockPB2) /* ** Return SQLITE_OK on success, SQLITE_BUSY on failure. */ static int _AFPFSSetLock( const char *path, unixFile *pFile, unsigned long long offset, unsigned long long length, int setLockFlag ){ struct ByteRangeLockPB2 pb; int err; pb.unLockFlag = setLockFlag ? 0 : 1; pb.startEndFlag = 0; pb.offset = offset; pb.length = length; pb.fd = pFile->h; OSTRACE5("AFPLOCK setting lock %s for %d in range %llx:%llx\n", (setLockFlag?"ON":"OFF"), pFile->h, offset, length); err = fsctl(path, afpfsByteRangeLock2FSCTL, &pb, 0); if ( err==-1 ) { int rc; int tErrno = errno; OSTRACE4("AFPLOCK failed to fsctl() '%s' %d %s\n", path, tErrno, strerror(tErrno)); rc = sqliteErrorFromPosixError(tErrno, setLockFlag ? SQLITE_IOERR_LOCK : SQLITE_IOERR_UNLOCK); /* error */ if( IS_LOCK_ERROR(rc) ){ pFile->lastErrno = tErrno; } return rc; } else { return SQLITE_OK; } } /* AFP-style reserved lock checking following the behavior of ** unixCheckReservedLock, see the unixCheckReservedLock function comments */ static int afpCheckReservedLock(sqlite3_file *id, int *pResOut){ int rc = SQLITE_OK; int reserved = 0; unixFile *pFile = (unixFile*)id; SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; ); assert( pFile ); afpLockingContext *context = (afpLockingContext *) pFile->lockingContext; /* Check if a thread in this process holds such a lock */ if( pFile->locktype>SHARED_LOCK ){ reserved = 1; } /* Otherwise see if some other process holds it. */ if( !reserved ){ /* lock the RESERVED byte */ int lrc = _AFPFSSetLock(context->filePath, pFile, RESERVED_BYTE, 1,1); if( SQLITE_OK==lrc ){ /* if we succeeded in taking the reserved lock, unlock it to restore ** the original state */ lrc = _AFPFSSetLock(context->filePath, pFile, RESERVED_BYTE, 1, 0); } else { /* if we failed to get the lock then someone else must have it */ reserved = 1; } if( IS_LOCK_ERROR(lrc) ){ rc=lrc; } } OSTRACE4("TEST WR-LOCK %d %d %d\n", pFile->h, rc, reserved); *pResOut = reserved; return rc; } /* AFP-style locking following the behavior of unixLock, see the unixLock ** function comments for details of lock management. */ static int afpLock(sqlite3_file *id, int locktype){ int rc = SQLITE_OK; unixFile *pFile = (unixFile*)id; afpLockingContext *context = (afpLockingContext *) pFile->lockingContext; assert( pFile ); OSTRACE5("LOCK %d %s was %s pid=%d\n", pFile->h, locktypeName(locktype), locktypeName(pFile->locktype), getpid()); /* If there is already a lock of this type or more restrictive on the ** unixFile, do nothing. Don't use the afp_end_lock: exit path, as ** enterMutex() hasn't been called yet. */ if( pFile->locktype>=locktype ){ OSTRACE3("LOCK %d %s ok (already held)\n", pFile->h, locktypeName(locktype)); return SQLITE_OK; } /* Make sure the locking sequence is correct */ assert( pFile->locktype!=NO_LOCK || locktype==SHARED_LOCK ); assert( locktype!=PENDING_LOCK ); assert( locktype!=RESERVED_LOCK || pFile->locktype==SHARED_LOCK ); /* This mutex is needed because pFile->pLock is shared across threads */ enterMutex(); /* Make sure the current thread owns the pFile. */ rc = transferOwnership(pFile); if( rc!=SQLITE_OK ){ leaveMutex(); return rc; } /* A PENDING lock is needed before acquiring a SHARED lock and before ** acquiring an EXCLUSIVE lock. For the SHARED lock, the PENDING will ** be released. */ if( locktype==SHARED_LOCK || (locktype==EXCLUSIVE_LOCK && pFile->locktypefilePath, pFile, PENDING_BYTE, 1, 1); if (failed) { rc = failed; goto afp_end_lock; } } /* If control gets to this point, then actually go ahead and make ** operating system calls for the specified lock. */ if( locktype==SHARED_LOCK ){ int lk, lrc1, lrc2, lrc1Errno; /* Now get the read-lock SHARED_LOCK */ /* note that the quality of the randomness doesn't matter that much */ lk = random(); context->sharedLockByte = (lk & 0x7fffffff)%(SHARED_SIZE - 1); lrc1 = _AFPFSSetLock(context->filePath, pFile, SHARED_FIRST+context->sharedLockByte, 1, 1); if( IS_LOCK_ERROR(lrc1) ){ lrc1Errno = pFile->lastErrno; } /* Drop the temporary PENDING lock */ lrc2 = _AFPFSSetLock(context->filePath, pFile, PENDING_BYTE, 1, 0); if( IS_LOCK_ERROR(lrc1) ) { pFile->lastErrno = lrc1Errno; rc = lrc1; goto afp_end_lock; } else if( IS_LOCK_ERROR(lrc2) ){ rc = lrc2; goto afp_end_lock; } else if( lrc1 != SQLITE_OK ) { rc = lrc1; } else { pFile->locktype = SHARED_LOCK; } }else{ /* The request was for a RESERVED or EXCLUSIVE lock. It is ** assumed that there is a SHARED or greater lock on the file ** already. */ int failed = 0; assert( 0!=pFile->locktype ); if (locktype >= RESERVED_LOCK && pFile->locktype < RESERVED_LOCK) { /* Acquire a RESERVED lock */ failed = _AFPFSSetLock(context->filePath, pFile, RESERVED_BYTE, 1,1); } if (!failed && locktype == EXCLUSIVE_LOCK) { /* Acquire an EXCLUSIVE lock */ /* Remove the shared lock before trying the range. we'll need to ** reestablish the shared lock if we can't get the afpUnlock */ if (!(failed = _AFPFSSetLock(context->filePath, pFile, SHARED_FIRST + context->sharedLockByte, 1, 0))) { /* now attemmpt to get the exclusive lock range */ failed = _AFPFSSetLock(context->filePath, pFile, SHARED_FIRST, SHARED_SIZE, 1); if (failed && (failed = _AFPFSSetLock(context->filePath, pFile, SHARED_FIRST + context->sharedLockByte, 1, 1))) { rc = failed; } } else { rc = failed; } } if( failed ){ rc = failed; } } if( rc==SQLITE_OK ){ pFile->locktype = locktype; }else if( locktype==EXCLUSIVE_LOCK ){ pFile->locktype = PENDING_LOCK; } afp_end_lock: leaveMutex(); OSTRACE4("LOCK %d %s %s\n", pFile->h, locktypeName(locktype), rc==SQLITE_OK ? "ok" : "failed"); return rc; } /* ** Lower the locking level on file descriptor pFile to locktype. locktype ** must be either NO_LOCK or SHARED_LOCK. ** ** If the locking level of the file descriptor is already at or below ** the requested locking level, this routine is a no-op. */ static int afpUnlock(sqlite3_file *id, int locktype) { int rc = SQLITE_OK; unixFile *pFile = (unixFile*)id; afpLockingContext *context = (afpLockingContext *) pFile->lockingContext; assert( pFile ); OSTRACE5("UNLOCK %d %d was %d pid=%d\n", pFile->h, locktype, pFile->locktype, getpid()); assert( locktype<=SHARED_LOCK ); if( pFile->locktype<=locktype ){ return SQLITE_OK; } if( CHECK_THREADID(pFile) ){ return SQLITE_MISUSE; } enterMutex(); int failed = SQLITE_OK; if( pFile->locktype>SHARED_LOCK ){ if( locktype==SHARED_LOCK ){ /* unlock the exclusive range - then re-establish the shared lock */ if (pFile->locktype==EXCLUSIVE_LOCK) { failed = _AFPFSSetLock(context->filePath, pFile, SHARED_FIRST, SHARED_SIZE, 0); if (!failed) { /* successfully removed the exclusive lock */ if ((failed = _AFPFSSetLock(context->filePath, pFile, SHARED_FIRST+ context->sharedLockByte, 1, 1))) { /* failed to re-establish our shared lock */ rc = failed; } } else { rc = failed; } } } if (rc == SQLITE_OK && pFile->locktype>=PENDING_LOCK) { if ((failed = _AFPFSSetLock(context->filePath, pFile, PENDING_BYTE, 1, 0))){ /* failed to release the pending lock */ rc = failed; } } if (rc == SQLITE_OK && pFile->locktype>=RESERVED_LOCK) { if ((failed = _AFPFSSetLock(context->filePath, pFile, RESERVED_BYTE, 1, 0))) { /* failed to release the reserved lock */ rc = failed; } } } if( locktype==NO_LOCK ){ int failed = _AFPFSSetLock(context->filePath, pFile, SHARED_FIRST + context->sharedLockByte, 1, 0); if (failed) { rc = failed; } } if (rc == SQLITE_OK) pFile->locktype = locktype; leaveMutex(); return rc; } /* ** Close a file & cleanup AFP specific locking context */ static int afpClose(sqlite3_file *id) { if( id ){ unixFile *pFile = (unixFile*)id; afpUnlock(id, NO_LOCK); sqlite3_free(pFile->lockingContext); } return closeUnixFile(id); } #pragma mark flock() style locking /* ** The flockLockingContext is not used */ typedef void flockLockingContext; /* flock-style reserved lock checking following the behavior of ** unixCheckReservedLock, see the unixCheckReservedLock function comments */ static int flockCheckReservedLock(sqlite3_file *id, int *pResOut){ int rc = SQLITE_OK; int reserved = 0; unixFile *pFile = (unixFile*)id; SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; ); assert( pFile ); /* Check if a thread in this process holds such a lock */ if( pFile->locktype>SHARED_LOCK ){ reserved = 1; } /* Otherwise see if some other process holds it. */ if( !reserved ){ /* attempt to get the lock */ int lrc = flock(pFile->h, LOCK_EX | LOCK_NB); if( !lrc ){ /* got the lock, unlock it */ lrc = flock(pFile->h, LOCK_UN); if ( lrc ) { int tErrno = errno; /* unlock failed with an error */ lrc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK); if( IS_LOCK_ERROR(lrc) ){ pFile->lastErrno = tErrno; rc = lrc; } } } else { int tErrno = errno; reserved = 1; /* someone else might have it reserved */ lrc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK); if( IS_LOCK_ERROR(lrc) ){ pFile->lastErrno = tErrno; rc = lrc; } } } OSTRACE4("TEST WR-LOCK %d %d %d\n", pFile->h, rc, reserved); *pResOut = reserved; return rc; } static int flockLock(sqlite3_file *id, int locktype) { int rc = SQLITE_OK; unixFile *pFile = (unixFile*)id; assert( pFile ); /* if we already have a lock, it is exclusive. ** Just adjust level and punt on outta here. */ if (pFile->locktype > NO_LOCK) { pFile->locktype = locktype; return SQLITE_OK; } /* grab an exclusive lock */ if (flock(pFile->h, LOCK_EX | LOCK_NB)) { int tErrno = errno; /* didn't get, must be busy */ rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK); if( IS_LOCK_ERROR(rc) ){ pFile->lastErrno = tErrno; } } else { /* got it, set the type and return ok */ pFile->locktype = locktype; } OSTRACE4("LOCK %d %s %s\n", pFile->h, locktypeName(locktype), rc==SQLITE_OK ? "ok" : "failed"); return rc; } static int flockUnlock(sqlite3_file *id, int locktype) { unixFile *pFile = (unixFile*)id; assert( pFile ); OSTRACE5("UNLOCK %d %d was %d pid=%d\n", pFile->h, locktype, pFile->locktype, getpid()); assert( locktype<=SHARED_LOCK ); /* no-op if possible */ if( pFile->locktype==locktype ){ return SQLITE_OK; } /* shared can just be set because we always have an exclusive */ if (locktype==SHARED_LOCK) { pFile->locktype = locktype; return SQLITE_OK; } /* no, really, unlock. */ int rc = flock(pFile->h, LOCK_UN); if (rc) { int r, tErrno = errno; r = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK); if( IS_LOCK_ERROR(r) ){ pFile->lastErrno = tErrno; } return r; } else { pFile->locktype = NO_LOCK; return SQLITE_OK; } } /* ** Close a file. */ static int flockClose(sqlite3_file *id) { if( id ){ flockUnlock(id, NO_LOCK); } return closeUnixFile(id); } #pragma mark Old-School .lock file based locking /* Dotlock-style reserved lock checking following the behavior of ** unixCheckReservedLock, see the unixCheckReservedLock function comments */ static int dotlockCheckReservedLock(sqlite3_file *id, int *pResOut) { int rc = SQLITE_OK; int reserved = 0; unixFile *pFile = (unixFile*)id; SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; ); assert( pFile ); /* Check if a thread in this process holds such a lock */ if( pFile->locktype>SHARED_LOCK ){ reserved = 1; } /* Otherwise see if some other process holds it. */ if( !reserved ){ char *zLockFile = (char *)pFile->lockingContext; struct stat statBuf; if( lstat(zLockFile, &statBuf)==0 ){ /* file exists, someone else has the lock */ reserved = 1; }else{ /* file does not exist, we could have it if we want it */ int tErrno = errno; if( ENOENT != tErrno ){ rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK); pFile->lastErrno = tErrno; } } } OSTRACE4("TEST WR-LOCK %d %d %d\n", pFile->h, rc, reserved); *pResOut = reserved; return rc; } static int dotlockLock(sqlite3_file *id, int locktype) { unixFile *pFile = (unixFile*)id; int fd; char *zLockFile = (char *)pFile->lockingContext; int rc=SQLITE_OK; /* if we already have a lock, it is exclusive. ** Just adjust level and punt on outta here. */ if (pFile->locktype > NO_LOCK) { pFile->locktype = locktype; /* Always update the timestamp on the old file */ utimes(zLockFile, NULL); rc = SQLITE_OK; goto dotlock_end_lock; } /* check to see if lock file already exists */ struct stat statBuf; if (lstat(zLockFile,&statBuf) == 0){ rc = SQLITE_BUSY; /* it does, busy */ goto dotlock_end_lock; } /* grab an exclusive lock */ fd = open(zLockFile,O_RDONLY|O_CREAT|O_EXCL,0600); if( fd<0 ){ /* failed to open/create the file, someone else may have stolen the lock */ int tErrno = errno; if( EEXIST == tErrno ){ rc = SQLITE_BUSY; } else { rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK); if( IS_LOCK_ERROR(rc) ){ pFile->lastErrno = tErrno; } } goto dotlock_end_lock; } close(fd); /* got it, set the type and return ok */ pFile->locktype = locktype; dotlock_end_lock: return rc; } static int dotlockUnlock(sqlite3_file *id, int locktype) { unixFile *pFile = (unixFile*)id; char *zLockFile = (char *)pFile->lockingContext; assert( pFile ); OSTRACE5("UNLOCK %d %d was %d pid=%d\n", pFile->h, locktype, pFile->locktype, getpid()); assert( locktype<=SHARED_LOCK ); /* no-op if possible */ if( pFile->locktype==locktype ){ return SQLITE_OK; } /* shared can just be set because we always have an exclusive */ if (locktype==SHARED_LOCK) { pFile->locktype = locktype; return SQLITE_OK; } /* no, really, unlock. */ if (unlink(zLockFile) ) { int rc, tErrno = errno; if( ENOENT != tErrno ){ rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK); } if( IS_LOCK_ERROR(rc) ){ pFile->lastErrno = tErrno; } return rc; } pFile->locktype = NO_LOCK; return SQLITE_OK; } /* ** Close a file. */ static int dotlockClose(sqlite3_file *id) { if( id ){ unixFile *pFile = (unixFile*)id; dotlockUnlock(id, NO_LOCK); sqlite3_free(pFile->lockingContext); } return closeUnixFile(id); } #endif /* SQLITE_ENABLE_LOCKING_STYLE */ /* ** The nolockLockingContext is void */ typedef void nolockLockingContext; static int nolockCheckReservedLock(sqlite3_file *id, int *pResOut) { *pResOut = 0; return SQLITE_OK; } static int nolockLock(sqlite3_file *id, int locktype) { return SQLITE_OK; } static int nolockUnlock(sqlite3_file *id, int locktype) { return SQLITE_OK; } /* ** Close a file. */ static int nolockClose(sqlite3_file *id) { return closeUnixFile(id); } /* ** Information and control of an open file handle. */ static int unixFileControl(sqlite3_file *id, int op, void *pArg){ switch( op ){ case SQLITE_FCNTL_LOCKSTATE: { *(int*)pArg = ((unixFile*)id)->locktype; return SQLITE_OK; } } return SQLITE_ERROR; } /* ** Return the sector size in bytes of the underlying block device for ** the specified file. This is almost always 512 bytes, but may be ** larger for some devices. ** ** SQLite code assumes this function cannot fail. It also assumes that ** if two files are created in the same file-system directory (i.e. ** a database and its journal file) that the sector size will be the ** same for both. */ static int unixSectorSize(sqlite3_file *id){ return SQLITE_DEFAULT_SECTOR_SIZE; } /* ** Return the device characteristics for the file. This is always 0. */ static int unixDeviceCharacteristics(sqlite3_file *id){ return 0; } /* ** Initialize the contents of the unixFile structure pointed to by pId. ** ** When locking extensions are enabled, the filepath and locking style ** are needed to determine the unixFile pMethod to use for locking operations. ** The locking-style specific lockingContext data structure is created ** and assigned here also. */ static int fillInUnixFile( sqlite3_vfs *pVfs, /* Pointer to vfs object */ int h, /* Open file descriptor of file being opened */ int dirfd, /* Directory file descriptor */ sqlite3_file *pId, /* Write to the unixFile structure here */ const char *zFilename, /* Name of the file being opened */ int noLock /* Omit locking if true */ ){ int eLockingStyle; unixFile *pNew = (unixFile *)pId; int rc = SQLITE_OK; /* Macro to define the static contents of an sqlite3_io_methods ** structure for a unix backend file. Different locking methods ** require different functions for the xClose, xLock, xUnlock and ** xCheckReservedLock methods. */ #define IOMETHODS(xClose, xLock, xUnlock, xCheckReservedLock) { \ 1, /* iVersion */ \ xClose, /* xClose */ \ unixRead, /* xRead */ \ unixWrite, /* xWrite */ \ unixTruncate, /* xTruncate */ \ unixSync, /* xSync */ \ unixFileSize, /* xFileSize */ \ xLock, /* xLock */ \ xUnlock, /* xUnlock */ \ xCheckReservedLock, /* xCheckReservedLock */ \ unixFileControl, /* xFileControl */ \ unixSectorSize, /* xSectorSize */ \ unixDeviceCharacteristics /* xDeviceCapabilities */ \ } static sqlite3_io_methods aIoMethod[] = { IOMETHODS(unixClose, unixLock, unixUnlock, unixCheckReservedLock) ,IOMETHODS(nolockClose, nolockLock, nolockUnlock, nolockCheckReservedLock) #if SQLITE_ENABLE_LOCKING_STYLE ,IOMETHODS(dotlockClose, dotlockLock, dotlockUnlock,dotlockCheckReservedLock) ,IOMETHODS(flockClose, flockLock, flockUnlock, flockCheckReservedLock) ,IOMETHODS(afpClose, afpLock, afpUnlock, afpCheckReservedLock) #endif }; /* The order of the IOMETHODS macros above is important. It must be the ** same order as the LOCKING_STYLE numbers */ assert(LOCKING_STYLE_POSIX==1); assert(LOCKING_STYLE_NONE==2); assert(LOCKING_STYLE_DOTFILE==3); assert(LOCKING_STYLE_FLOCK==4); assert(LOCKING_STYLE_AFP==5); assert( pNew->pLock==NULL ); assert( pNew->pOpen==NULL ); OSTRACE3("OPEN %-3d %s\n", h, zFilename); pNew->h = h; pNew->dirfd = dirfd; SET_THREADID(pNew); if( noLock ){ eLockingStyle = LOCKING_STYLE_NONE; }else{ eLockingStyle = detectLockingStyle(pVfs, zFilename, h); } switch( eLockingStyle ){ case LOCKING_STYLE_POSIX: { enterMutex(); rc = findLockInfo(h, &pNew->pLock, &pNew->pOpen); leaveMutex(); break; } #if SQLITE_ENABLE_LOCKING_STYLE case LOCKING_STYLE_AFP: { /* AFP locking uses the file path so it needs to be included in ** the afpLockingContext. */ afpLockingContext *pCtx; pNew->lockingContext = pCtx = sqlite3_malloc( sizeof(*pCtx) ); if( pCtx==0 ){ rc = SQLITE_NOMEM; }else{ /* NB: zFilename exists and remains valid until the file is closed ** according to requirement F11141. So we do not need to make a ** copy of the filename. */ pCtx->filePath = zFilename; srandomdev(); } break; } case LOCKING_STYLE_DOTFILE: { /* Dotfile locking uses the file path so it needs to be included in ** the dotlockLockingContext */ char *zLockFile; int nFilename; nFilename = strlen(zFilename) + 6; zLockFile = (char *)sqlite3_malloc(nFilename); if( zLockFile==0 ){ rc = SQLITE_NOMEM; }else{ sqlite3_snprintf(nFilename, zLockFile, "%s.lock", zFilename); } pNew->lockingContext = zLockFile; break; } case LOCKING_STYLE_FLOCK: case LOCKING_STYLE_NONE: break; #endif } pNew->lastErrno = 0; if( rc!=SQLITE_OK ){ if( dirfd>=0 ) close(dirfd); close(h); }else{ pNew->pMethod = &aIoMethod[eLockingStyle-1]; OpenCounter(+1); } return rc; } /* ** Open a file descriptor to the directory containing file zFilename. ** If successful, *pFd is set to the opened file descriptor and ** SQLITE_OK is returned. If an error occurs, either SQLITE_NOMEM ** or SQLITE_CANTOPEN is returned and *pFd is set to an undefined ** value. ** ** If SQLITE_OK is returned, the caller is responsible for closing ** the file descriptor *pFd using close(). */ static int openDirectory(const char *zFilename, int *pFd){ int ii; int fd = -1; char zDirname[MAX_PATHNAME+1]; sqlite3_snprintf(MAX_PATHNAME, zDirname, "%s", zFilename); for(ii=strlen(zDirname); ii>=0 && zDirname[ii]!='/'; ii--); if( ii>0 ){ zDirname[ii] = '\0'; fd = open(zDirname, O_RDONLY|O_BINARY, 0); if( fd>=0 ){ #ifdef FD_CLOEXEC fcntl(fd, F_SETFD, fcntl(fd, F_GETFD, 0) | FD_CLOEXEC); #endif OSTRACE3("OPENDIR %-3d %s\n", fd, zDirname); } } *pFd = fd; return (fd>=0?SQLITE_OK:SQLITE_CANTOPEN); } /* ** Create a temporary file name in zBuf. zBuf must be allocated ** by the calling process and must be big enough to hold at least ** pVfs->mxPathname bytes. */ static int getTempname(int nBuf, char *zBuf){ static const char *azDirs[] = { 0, "/var/tmp", "/usr/tmp", "/tmp", ".", }; static const unsigned char zChars[] = "abcdefghijklmnopqrstuvwxyz" "ABCDEFGHIJKLMNOPQRSTUVWXYZ" "0123456789"; int i, j; struct stat buf; const char *zDir = "."; /* It's odd to simulate an io-error here, but really this is just ** using the io-error infrastructure to test that SQLite handles this ** function failing. */ SimulateIOError( return SQLITE_IOERR ); azDirs[0] = sqlite3_temp_directory; for(i=0; i= nBuf ){ return SQLITE_ERROR; } do{ sqlite3_snprintf(nBuf-17, zBuf, "%s/"SQLITE_TEMP_FILE_PREFIX, zDir); j = strlen(zBuf); sqlite3_randomness(15, &zBuf[j]); for(i=0; i<15; i++, j++){ zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ]; } zBuf[j] = 0; }while( access(zBuf,0)==0 ); return SQLITE_OK; } /* ** Open the file zPath. ** ** Previously, the SQLite OS layer used three functions in place of this ** one: ** ** sqlite3OsOpenReadWrite(); ** sqlite3OsOpenReadOnly(); ** sqlite3OsOpenExclusive(); ** ** These calls correspond to the following combinations of flags: ** ** ReadWrite() -> (READWRITE | CREATE) ** ReadOnly() -> (READONLY) ** OpenExclusive() -> (READWRITE | CREATE | EXCLUSIVE) ** ** The old OpenExclusive() accepted a boolean argument - "delFlag". If ** true, the file was configured to be automatically deleted when the ** file handle closed. To achieve the same effect using this new ** interface, add the DELETEONCLOSE flag to those specified above for ** OpenExclusive(). */ static int unixOpen( sqlite3_vfs *pVfs, const char *zPath, sqlite3_file *pFile, int flags, int *pOutFlags ){ int fd = 0; /* File descriptor returned by open() */ int dirfd = -1; /* Directory file descriptor */ int oflags = 0; /* Flags to pass to open() */ int eType = flags&0xFFFFFF00; /* Type of file to open */ int noLock; /* True to omit locking primitives */ int isExclusive = (flags & SQLITE_OPEN_EXCLUSIVE); int isDelete = (flags & SQLITE_OPEN_DELETEONCLOSE); int isCreate = (flags & SQLITE_OPEN_CREATE); int isReadonly = (flags & SQLITE_OPEN_READONLY); int isReadWrite = (flags & SQLITE_OPEN_READWRITE); /* If creating a master or main-file journal, this function will open ** a file-descriptor on the directory too. The first time unixSync() ** is called the directory file descriptor will be fsync()ed and close()d. */ int isOpenDirectory = (isCreate && (eType==SQLITE_OPEN_MASTER_JOURNAL || eType==SQLITE_OPEN_MAIN_JOURNAL) ); /* If argument zPath is a NULL pointer, this function is required to open ** a temporary file. Use this buffer to store the file name in. */ char zTmpname[MAX_PATHNAME+1]; const char *zName = zPath; /* Check the following statements are true: ** ** (a) Exactly one of the READWRITE and READONLY flags must be set, and ** (b) if CREATE is set, then READWRITE must also be set, and ** (c) if EXCLUSIVE is set, then CREATE must also be set. ** (d) if DELETEONCLOSE is set, then CREATE must also be set. */ assert((isReadonly==0 || isReadWrite==0) && (isReadWrite || isReadonly)); assert(isCreate==0 || isReadWrite); assert(isExclusive==0 || isCreate); assert(isDelete==0 || isCreate); /* The main DB, main journal, and master journal are never automatically ** deleted */ assert( eType!=SQLITE_OPEN_MAIN_DB || !isDelete ); assert( eType!=SQLITE_OPEN_MAIN_JOURNAL || !isDelete ); assert( eType!=SQLITE_OPEN_MASTER_JOURNAL || !isDelete ); /* Assert that the upper layer has set one of the "file-type" flags. */ assert( eType==SQLITE_OPEN_MAIN_DB || eType==SQLITE_OPEN_TEMP_DB || eType==SQLITE_OPEN_MAIN_JOURNAL || eType==SQLITE_OPEN_TEMP_JOURNAL || eType==SQLITE_OPEN_SUBJOURNAL || eType==SQLITE_OPEN_MASTER_JOURNAL || eType==SQLITE_OPEN_TRANSIENT_DB ); memset(pFile, 0, sizeof(unixFile)); if( !zName ){ int rc; assert(isDelete && !isOpenDirectory); rc = getTempname(MAX_PATHNAME+1, zTmpname); if( rc!=SQLITE_OK ){ return rc; } zName = zTmpname; } if( isReadonly ) oflags |= O_RDONLY; if( isReadWrite ) oflags |= O_RDWR; if( isCreate ) oflags |= O_CREAT; if( isExclusive ) oflags |= (O_EXCL|O_NOFOLLOW); oflags |= (O_LARGEFILE|O_BINARY); fd = open(zName, oflags, isDelete?0600:SQLITE_DEFAULT_FILE_PERMISSIONS); if( fd<0 && errno!=EISDIR && isReadWrite && !isExclusive ){ /* Failed to open the file for read/write access. Try read-only. */ flags &= ~(SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE); flags |= SQLITE_OPEN_READONLY; return unixOpen(pVfs, zPath, pFile, flags, pOutFlags); } if( fd<0 ){ return SQLITE_CANTOPEN; } if( isDelete ){ unlink(zName); } if( pOutFlags ){ *pOutFlags = flags; } assert(fd!=0); if( isOpenDirectory ){ int rc = openDirectory(zPath, &dirfd); if( rc!=SQLITE_OK ){ close(fd); return rc; } } #ifdef FD_CLOEXEC fcntl(fd, F_SETFD, fcntl(fd, F_GETFD, 0) | FD_CLOEXEC); #endif noLock = eType!=SQLITE_OPEN_MAIN_DB; return fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock); } /* ** Delete the file at zPath. If the dirSync argument is true, fsync() ** the directory after deleting the file. */ static int unixDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){ int rc = SQLITE_OK; SimulateIOError(return SQLITE_IOERR_DELETE); unlink(zPath); if( dirSync ){ int fd; rc = openDirectory(zPath, &fd); if( rc==SQLITE_OK ){ if( fsync(fd) ){ rc = SQLITE_IOERR_DIR_FSYNC; } close(fd); } } return rc; } /* ** Test the existance of or access permissions of file zPath. The ** test performed depends on the value of flags: ** ** SQLITE_ACCESS_EXISTS: Return 1 if the file exists ** SQLITE_ACCESS_READWRITE: Return 1 if the file is read and writable. ** SQLITE_ACCESS_READONLY: Return 1 if the file is readable. ** ** Otherwise return 0. */ static int unixAccess( sqlite3_vfs *pVfs, const char *zPath, int flags, int *pResOut ){ int amode = 0; SimulateIOError( return SQLITE_IOERR_ACCESS; ); switch( flags ){ case SQLITE_ACCESS_EXISTS: amode = F_OK; break; case SQLITE_ACCESS_READWRITE: amode = W_OK|R_OK; break; case SQLITE_ACCESS_READ: amode = R_OK; break; default: assert(!"Invalid flags argument"); } *pResOut = (access(zPath, amode)==0); return SQLITE_OK; } /* ** Turn a relative pathname into a full pathname. The relative path ** is stored as a nul-terminated string in the buffer pointed to by ** zPath. ** ** zOut points to a buffer of at least sqlite3_vfs.mxPathname bytes ** (in this case, MAX_PATHNAME bytes). The full-path is written to ** this buffer before returning. */ static int unixFullPathname( sqlite3_vfs *pVfs, /* Pointer to vfs object */ const char *zPath, /* Possibly relative input path */ int nOut, /* Size of output buffer in bytes */ char *zOut /* Output buffer */ ){ /* It's odd to simulate an io-error here, but really this is just ** using the io-error infrastructure to test that SQLite handles this ** function failing. This function could fail if, for example, the ** current working directly has been unlinked. */ SimulateIOError( return SQLITE_ERROR ); assert( pVfs->mxPathname==MAX_PATHNAME ); zOut[nOut-1] = '\0'; if( zPath[0]=='/' ){ sqlite3_snprintf(nOut, zOut, "%s", zPath); }else{ int nCwd; if( getcwd(zOut, nOut-1)==0 ){ return SQLITE_CANTOPEN; } nCwd = strlen(zOut); sqlite3_snprintf(nOut-nCwd, &zOut[nCwd], "/%s", zPath); } return SQLITE_OK; #if 0 /* ** Remove "/./" path elements and convert "/A/./" path elements ** to just "/". */ if( zFull ){ int i, j; for(i=j=0; zFull[i]; i++){ if( zFull[i]=='/' ){ if( zFull[i+1]=='/' ) continue; if( zFull[i+1]=='.' && zFull[i+2]=='/' ){ i += 1; continue; } if( zFull[i+1]=='.' && zFull[i+2]=='.' && zFull[i+3]=='/' ){ while( j>0 && zFull[j-1]!='/' ){ j--; } i += 3; continue; } } zFull[j++] = zFull[i]; } zFull[j] = 0; } #endif } #ifndef SQLITE_OMIT_LOAD_EXTENSION /* ** Interfaces for opening a shared library, finding entry points ** within the shared library, and closing the shared library. */ #include static void *unixDlOpen(sqlite3_vfs *pVfs, const char *zFilename){ return dlopen(zFilename, RTLD_NOW | RTLD_GLOBAL); } /* ** SQLite calls this function immediately after a call to unixDlSym() or ** unixDlOpen() fails (returns a null pointer). If a more detailed error ** message is available, it is written to zBufOut. If no error message ** is available, zBufOut is left unmodified and SQLite uses a default ** error message. */ static void unixDlError(sqlite3_vfs *pVfs, int nBuf, char *zBufOut){ char *zErr; enterMutex(); zErr = dlerror(); if( zErr ){ sqlite3_snprintf(nBuf, zBufOut, "%s", zErr); } leaveMutex(); } static void *unixDlSym(sqlite3_vfs *pVfs, void *pHandle, const char *zSymbol){ return dlsym(pHandle, zSymbol); } static void unixDlClose(sqlite3_vfs *pVfs, void *pHandle){ dlclose(pHandle); } #else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */ #define unixDlOpen 0 #define unixDlError 0 #define unixDlSym 0 #define unixDlClose 0 #endif /* ** Write nBuf bytes of random data to the supplied buffer zBuf. */ static int unixRandomness(sqlite3_vfs *pVfs, int nBuf, char *zBuf){ assert(nBuf>=(sizeof(time_t)+sizeof(int))); /* 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, nBuf); #if !defined(SQLITE_TEST) { int pid, fd; fd = open("/dev/urandom", O_RDONLY); if( fd<0 ){ time_t t; time(&t); memcpy(zBuf, &t, sizeof(t)); pid = getpid(); memcpy(&zBuf[sizeof(t)], &pid, sizeof(pid)); }else{ read(fd, zBuf, nBuf); close(fd); } } #endif return SQLITE_OK; } /* ** Sleep for a little while. Return the amount of time slept. ** The argument is the number of microseconds we want to sleep. ** The return value is the number of microseconds of sleep actually ** requested from the underlying operating system, a number which ** might be greater than or equal to the argument, but not less ** than the argument. */ static int unixSleep(sqlite3_vfs *pVfs, int microseconds){ #if defined(HAVE_USLEEP) && HAVE_USLEEP usleep(microseconds); return microseconds; #else int seconds = (microseconds+999999)/1000000; sleep(seconds); return seconds*1000000; #endif } /* ** 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. */ static int unixCurrentTime(sqlite3_vfs *pVfs, double *prNow){ #ifdef NO_GETTOD time_t t; time(&t); *prNow = t/86400.0 + 2440587.5; #else struct timeval sNow; gettimeofday(&sNow, 0); *prNow = 2440587.5 + sNow.tv_sec/86400.0 + sNow.tv_usec/86400000000.0; #endif #ifdef SQLITE_TEST if( sqlite3_current_time ){ *prNow = sqlite3_current_time/86400.0 + 2440587.5; } #endif return 0; } static int unixGetLastError(sqlite3_vfs *pVfs, int nBuf, char *zBuf){ return 0; } /* ** Initialize the operating system interface. */ int sqlite3_os_init(void){ /* Macro to define the static contents of an sqlite3_vfs structure for ** the unix backend. The two parameters are the values to use for ** the sqlite3_vfs.zName and sqlite3_vfs.pAppData fields, respectively. ** */ #define UNIXVFS(zVfsName, pVfsAppData) { \ 1, /* iVersion */ \ sizeof(unixFile), /* szOsFile */ \ MAX_PATHNAME, /* mxPathname */ \ 0, /* pNext */ \ zVfsName, /* zName */ \ (void *)pVfsAppData, /* pAppData */ \ unixOpen, /* xOpen */ \ unixDelete, /* xDelete */ \ unixAccess, /* xAccess */ \ unixFullPathname, /* xFullPathname */ \ unixDlOpen, /* xDlOpen */ \ unixDlError, /* xDlError */ \ unixDlSym, /* xDlSym */ \ unixDlClose, /* xDlClose */ \ unixRandomness, /* xRandomness */ \ unixSleep, /* xSleep */ \ unixCurrentTime, /* xCurrentTime */ \ unixGetLastError /* xGetLastError */ \ } static sqlite3_vfs unixVfs = UNIXVFS("unix", 0); #if SQLITE_ENABLE_LOCKING_STYLE int i; static sqlite3_vfs aVfs[] = { UNIXVFS("unix-posix", LOCKING_STYLE_POSIX), UNIXVFS("unix-afp", LOCKING_STYLE_AFP), UNIXVFS("unix-flock", LOCKING_STYLE_FLOCK), UNIXVFS("unix-dotfile", LOCKING_STYLE_DOTFILE), UNIXVFS("unix-none", LOCKING_STYLE_NONE) }; for(i=0; i<(sizeof(aVfs)/sizeof(sqlite3_vfs)); i++){ sqlite3_vfs_register(&aVfs[i], 0); } #endif sqlite3_vfs_register(&unixVfs, 1); return SQLITE_OK; } /* ** Shutdown the operating system interface. This is a no-op for unix. */ int sqlite3_os_end(void){ return SQLITE_OK; } #endif /* SQLITE_OS_UNIX */