diff options
Diffstat (limited to 'src/os_unix.c')
| -rw-r--r-- | src/os_unix.c | 1926 |
1 files changed, 967 insertions, 959 deletions
diff --git a/src/os_unix.c b/src/os_unix.c index 3d25b306b..df483af13 100644 --- a/src/os_unix.c +++ b/src/os_unix.c @@ -28,22 +28,22 @@ ** ** * General-purpose declarations and utility functions. ** * Unique file ID logic used by VxWorks. -** * Various locking primitive implementations: +** * Various locking primitive implementations (all except proxy locking): ** + for Posix Advisory Locks ** + for no-op locks ** + for dot-file locks ** + for flock() locking ** + for named semaphore locks (VxWorks only) ** + for AFP filesystem locks (MacOSX only) -** + for proxy locks (MacOSX only) ** * sqlite3_file methods not associated with locking. ** * Definitions of sqlite3_io_methods objects for all locking ** methods plus "finder" functions for each locking method. ** * sqlite3_vfs method implementations. +** * Locking primitives for the proxy uber-locking-method. (MacOSX only) ** * Definitions of sqlite3_vfs objects for all locking methods ** plus implementations of sqlite3_os_init() and sqlite3_os_end(). ** -** $Id: os_unix.c,v 1.226 2008/12/03 21:26:20 aswift Exp $ +** $Id: os_unix.c,v 1.227 2008/12/03 22:32:45 drh Exp $ */ #include "sqliteInt.h" #if SQLITE_OS_UNIX /* This file is used on unix only */ @@ -755,13 +755,15 @@ static struct unixOpenCnt *openList = 0; ** 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 +#if SQLITE_THREADSAFE && defined(__linux__) +# ifndef SQLITE_THREAD_OVERRIDE_LOCK +# define SQLITE_THREAD_OVERRIDE_LOCK -1 +# endif +# ifdef SQLITE_TEST int threadsOverrideEachOthersLocks = SQLITE_THREAD_OVERRIDE_LOCK; -#else +# else static int threadsOverrideEachOthersLocks = SQLITE_THREAD_OVERRIDE_LOCK; +# endif #endif /* @@ -824,14 +826,6 @@ static void testThreadLockingBehavior(int fd_orig){ if( d.result!=0 ) return; threadsOverrideEachOthersLocks = (d.lock.l_type==F_UNLCK); } -#elif SQLITE_THREADSAFE -/* -** On anything other than linux, assume threads override each others locks. -*/ -static void testThreadLockingBehavior(int fd_orig){ - UNUSED_PARAMETER(fd_orig); - threadsOverrideEachOthersLocks = 1; -} #endif /* SQLITE_THERADSAFE && defined(__linux__) */ /* @@ -2527,7 +2521,6 @@ static int afpUnlock(sqlite3_file *id, int locktype) { } } } -end_afpunlock: unixLeaveMutex(); if( rc==SQLITE_OK ) pFile->locktype = locktype; return rc; @@ -2577,893 +2570,6 @@ static int afpClose(sqlite3_file *id) { ********************* End of the AFP lock implementation ********************** ******************************************************************************/ -/****************************************************************************** -************************** Begin Proxy Locking ******************************** -** -** -** The default locking schemes in SQLite use byte-range locks on the -** database file to coordinate safe, concurrent access by multiple readers -** and writers [http://sqlite.org/lockingv3.html]. The five file locking -** states (UNLOCKED, PENDING, SHARED, RESERVED, EXCLUSIVE) are implemented -** as POSIX read & write locks over fixed set of locations (via fsctl), -** on AFP and SMB only exclusive byte-range locks are available via fsctl -** with _IOWR('z', 23, struct ByteRangeLockPB2) to track the same 5 states. -** To simulate a F_RDLCK on the shared range, on AFP a randomly selected -** address in the shared range is taken for a SHARED lock, the entire -** shared range is taken for an EXCLUSIVE lock): -** -** PENDING_BYTE 0x40000000 -** RESERVED_BYTE 0x40000001 -** SHARED_RANGE 0x40000002 -> 0x40000200 -** -** This works well on the local file system, but shows a nearly 100x -** slowdown in read performance on AFP because the AFP client disables -** the read cache when byte-range locks are present. Enabling the read -** cache exposes a cache coherency problem that is present on all OS X -** supported network file systems. NFS and AFP both observe the -** close-to-open semantics for ensuring cache coherency -** [http://nfs.sourceforge.net/#faq_a8], which does not effectively -** address the requirements for concurrent database access by multiple -** readers and writers -** [http://www.nabble.com/SQLite-on-NFS-cache-coherency-td15655701.html]. -** -** To address the performance and cache coherency issues, proxy file locking -** changes the way database access is controlled by limiting access to a -** single host at a time and moving file locks off of the database file -** and onto a proxy file on the local file system. -** -** -** Using proxy locks -** ----------------- -** -** C APIs -** -** sqlite3_file_control(db, dbname, SQLITE_SET_LOCKPROXYFILE, -** <proxy_path> | ":auto:"); -** sqlite3_file_control(db, dbname, SQLITE_GET_LOCKPROXYFILE, &<proxy_path>); -** -** -** SQL pragmas -** -** PRAGMA [database.]lock_proxy_file=<proxy_path> | :auto: -** PRAGMA [database.]lock_proxy_file -** -** Specifying ":auto:" means that if there is a conch file with a matching -** host ID in it, the proxy path in the conch file will be used, otherwise -** a proxy path based on the user's temp dir -** (via confstr(_CS_DARWIN_USER_TEMP_DIR,...)) will be used and the -** actual proxy file name is generated from the name and path of the -** database file. For example: -** -** For database path "/Users/me/foo.db" -** The lock path will be "<tmpdir>/sqliteplocks/_Users_me_foo.db:auto:") -** -** Once a lock proxy is configured for a database connection, it can not -** be removed, however it may be switched to a different proxy path via -** the above APIs (assuming the conch file is not being held by another -** connection or process). -** -** -** How proxy locking works -** ----------------------- -** -** Proxy file locking relies primarily on two new supporting files: -** -** * conch file to limit access to the database file to a single host -** at a time -** -** * proxy file to act as a proxy for the advisory locks normally -** taken on the database -** -** The conch file - to use a proxy file, sqlite must first "hold the conch" -** by taking an sqlite-style shared lock on the conch file, reading the -** contents and comparing the host's unique host ID (see below) and lock -** proxy path against the values stored in the conch. The conch file is -** stored in the same directory as the database file and the file name -** is patterned after the database file name as ".<databasename>-conch". -** If the conch file does not exist, or it's contents do not match the -** host ID and/or proxy path, then the lock is escalated to an exclusive -** lock and the conch file contents is updated with the host ID and proxy -** path and the lock is downgraded to a shared lock again. If the conch -** is held by another process (with a shared lock), the exclusive lock -** will fail and SQLITE_BUSY is returned. -** -** The proxy file - a single-byte file used for all advisory file locks -** normally taken on the database file. This allows for safe sharing -** of the database file for multiple readers and writers on the same -** host (the conch ensures that they all use the same local lock file). -** -** There is a third file - the host ID file - used as a persistent record -** of a unique identifier for the host, a 128-byte unique host id file -** in the path defined by the HOSTIDPATH macro (default value is -** /Library/Caches/.com.apple.sqliteConchHostId). -** -** Requesting the lock proxy does not immediately take the conch, it is -** only taken when the first request to lock database file is made. -** This matches the semantics of the traditional locking behavior, where -** opening a connection to a database file does not take a lock on it. -** The shared lock and an open file descriptor are maintained until -** the connection to the database is closed. -** -** The proxy file and the lock file are never deleted so they only need -** to be created the first time they are used. -** -** Configuration options -** --------------------- -** -** SQLITE_PREFER_PROXY_LOCKING -** -** Database files accessed on non-local file systems are -** automatically configured for proxy locking, lock files are -** named automatically using the same logic as -** PRAGMA lock_proxy_file=":auto:" -** -** SQLITE_PROXY_DEBUG -** -** Enables the logging of error messages during host id file -** retrieval and creation -** -** HOSTIDPATH -** -** Overrides the default host ID file path location -** -** LOCKPROXYDIR -** -** Overrides the default directory used for lock proxy files that -** are named automatically via the ":auto:" setting -** -** SQLITE_DEFAULT_PROXYDIR_PERMISSIONS -** -** Permissions to use when creating a directory for storing the -** lock proxy files, only used when LOCKPROXYDIR is not set. -** -** -** As mentioned above, when compiled with SQLITE_PREFER_PROXY_LOCKING, -** setting the environment variable SQLITE_FORCE_PROXY_LOCKING to 1 will -** force proxy locking to be used for every database file opened, and 0 -** will force automatic proxy locking to be disabled for all database -** files (explicity calling the SQLITE_SET_LOCKPROXYFILE pragma or -** sqlite_file_control API is not affected by SQLITE_FORCE_PROXY_LOCKING). -*/ - -/* -** Proxy locking is only available on MacOSX -*/ -#if defined(__DARWIN__) && SQLITE_ENABLE_LOCKING_STYLE - -/* -** Forward reference -*/ -static int fillInUnixFile( - sqlite3_vfs *pVfs, - int h, - int dirfd, - sqlite3_file *pId, - const char *zFilename, - int noLock, - int isDelete -); - - -#ifdef SQLITE_TEST -/* simulate multiple hosts by creating unique hostid file paths */ -int sqlite3_hostid_num = 0; -#endif - -/* -** The proxyLockingContext has the path and file structures for the remote -** and local proxy files in it -*/ -typedef struct proxyLockingContext proxyLockingContext; -struct proxyLockingContext { - unixFile *conchFile; /* Open conch file */ - char *conchFilePath; /* Name of the conch file */ - unixFile *lockProxy; /* Open proxy lock file */ - char *lockProxyPath; /* Name of the proxy lock file */ - char *dbPath; /* Name of the open file */ - int conchHeld; /* True if the conch is currently held */ - void *oldLockingContext; /* Original lockingcontext to restore on close */ - sqlite3_io_methods const *pOldMethod; /* Original I/O methods for close */ -}; - -/* HOSTIDLEN and CONCHLEN both include space for the string -** terminating nul -*/ -#define HOSTIDLEN 128 -#define CONCHLEN (MAXPATHLEN+HOSTIDLEN+1) -#ifndef HOSTIDPATH -# define HOSTIDPATH "/Library/Caches/.com.apple.sqliteConchHostId" -#endif - -/* basically a copy of unixRandomness with different -** test behavior built in */ -static int proxyGenerateHostID(char *pHostID){ - int pid, fd, i, len; - unsigned char *key = (unsigned char *)pHostID; - - memset(key, 0, HOSTIDLEN); - len = 0; - fd = open("/dev/urandom", O_RDONLY); - if( fd>=0 ){ - len = read(fd, key, HOSTIDLEN); - close(fd); /* silently leak the fd if it fails */ - } - if( len < HOSTIDLEN ){ - time_t t; - time(&t); - memcpy(key, &t, sizeof(t)); - pid = getpid(); - memcpy(&key[sizeof(t)], &pid, sizeof(pid)); - } - -#ifdef MAKE_PRETTY_HOSTID - /* filter the bytes into printable ascii characters and NUL terminate */ - key[(HOSTIDLEN-1)] = 0x00; - for( i=0; i<(HOSTIDLEN-1); i++ ){ - unsigned char pa = key[i]&0x7F; - if( pa<0x20 ){ - key[i] = (key[i]&0x80 == 0x80) ? pa+0x40 : pa+0x20; - }else if( pa==0x7F ){ - key[i] = (key[i]&0x80 == 0x80) ? pa=0x20 : pa+0x7E; - } - } -#endif - return SQLITE_OK; -} - -/* writes the host id path to path, path should be an pre-allocated buffer -** with enough space for a path -*/ -static int proxyGetHostIDPath(char *path, size_t len){ - strlcpy(path, HOSTIDPATH, len); -#ifdef SQLITE_TEST - if( sqlite3_hostid_num>0 ){ - char suffix[2] = "1"; - suffix[0] = suffix[0] + sqlite3_hostid_num; - strlcat(path, suffix, len); - } -#endif - OSTRACE3("GETHOSTIDPATH %s pid=%d\n", path, getpid()); -} - -/* get the host ID from a sqlite hostid file stored in the -** user-specific tmp directory, create the ID if it's not there already -*/ -static int proxyGetHostID(char *pHostID, int *pError){ - int fd; - char path[MAXPATHLEN]; - size_t len; - int rc=SQLITE_OK; - - proxyGetHostIDPath(path, MAXPATHLEN); - /* try to create the host ID file, if it already exists read the contents */ - fd = open(path, O_CREAT|O_WRONLY|O_EXCL, 0644); - if( fd<0 ){ - int err=errno; - - if( err!=EEXIST ){ -#ifdef SQLITE_PROXY_DEBUG /* set the sqlite error message instead */ - fprintf(stderr, "sqlite error creating host ID file %s: %s\n", - path, strerror(err)); -#endif - return SQLITE_PERM; - } - /* couldn't create the file, read it instead */ - fd = open(path, O_RDONLY|O_EXCL); - if( fd<0 ){ - int err = errno; -#ifdef SQLITE_PROXY_DEBUG /* set the sqlite error message instead */ - fprintf(stderr, "sqlite error opening host ID file %s: %s\n", - path, strerror(err)); -#endif - return SQLITE_PERM; - } - len = pread(fd, pHostID, HOSTIDLEN, 0); - if( len<0 ){ - *pError = errno; - rc = SQLITE_IOERR_READ; - }else if( len<HOSTIDLEN ){ - *pError = 0; - rc = SQLITE_IOERR_SHORT_READ; - } - close(fd); /* silently leak the fd if it fails */ - OSTRACE3("GETHOSTID read %s pid=%d\n", pHostID, getpid()); - return rc; - }else{ - int i; - /* we're creating the host ID file (use a random string of bytes) */ - proxyGenerateHostID(pHostID); - len = pwrite(fd, pHostID, HOSTIDLEN, 0); - if( len<0 ){ - *pError = errno; - rc = SQLITE_IOERR_WRITE; - }else if( len<HOSTIDLEN ){ - *pError = 0; - rc = SQLITE_IOERR_WRITE; - } - close(fd); /* silently leak the fd if it fails */ - OSTRACE3("GETHOSTID wrote %s pid=%d\n", pHostID, getpid()); - return rc; - } -} - -static int proxyGetLockPath(const char *dbPath, char *lPath, size_t maxLen){ - int len; - int dbLen; - int i; - -#ifdef LOCKPROXYDIR - len = strlcpy(lPath, LOCKPROXYDIR, maxLen); -#else -# ifdef _CS_DARWIN_USER_TEMP_DIR - { - char utdir[MAXPATHLEN]; - - confstr(_CS_DARWIN_USER_TEMP_DIR, lPath, maxLen); - len = strlcat(lPath, "sqliteplocks", maxLen); - if( mkdir(lPath, SQLITE_DEFAULT_PROXYDIR_PERMISSIONS) ){ - /* if mkdir fails, handle as lock file creation failure */ - int err = errno; -# ifdef SQLITE_DEBUG - if( err!=EEXIST ){ - fprintf(stderr, "proxyGetLockPath: mkdir(%s,0%o) error %d %s\n", lPath, - SQLITE_DEFAULT_PROXYDIR_PERMISSIONS, err, strerror(err)); - } -# endif - }else{ - OSTRACE3("GETLOCKPATH mkdir %s pid=%d\n", lPath, getpid()); - } - - } -# else - len = strlcpy(lPath, "/tmp/", maxLen); -# endif -#endif - - if( lPath[len-1]!='/' ){ - len = strlcat(lPath, "/", maxLen); - } - - /* transform the db path to a unique cache name */ - dbLen = strlen(dbPath); - for( i=0; i<dbLen && (i+len+7)<maxLen; i++){ - char c = dbPath[i]; - lPath[i+len] = (c=='/')?'_':c; - } - lPath[i+len]='\0'; - strlcat(lPath, ":auto:", maxLen); - return SQLITE_OK; -} - -/* -** Create a new VFS file descriptor (stored in memory obtained from -** sqlite3_malloc) and open the file named "path" in the file descriptor. -** -** The caller is responsible not only for closing the file descriptor -** but also for freeing the memory associated with the file descriptor. -*/ -static int proxyCreateUnixFile(const char *path, unixFile **ppFile) { - int fd; - int dirfd = -1; - unixFile *pNew; - int rc = SQLITE_OK; - - fd = open(path, O_RDWR | O_CREAT, SQLITE_DEFAULT_FILE_PERMISSIONS); - if( fd<0 ){ - return SQLITE_CANTOPEN; - } - - pNew = (unixFile *)sqlite3_malloc(sizeof(unixFile)); - if( pNew==NULL ){ - rc = SQLITE_NOMEM; - goto end_create_proxy; - } - memset(pNew, 0, sizeof(unixFile)); - - rc = fillInUnixFile(NULL, fd, dirfd, (sqlite3_file*)pNew, path, 0, 0); - if( rc==SQLITE_OK ){ - *ppFile = pNew; - return SQLITE_OK; - } -end_create_proxy: - close(fd); /* silently leak fd if error, we're already in error */ - sqlite3_free(pNew); - return rc; -} -static const sqlite3_io_methods afpIoMethods; -static int unixWrite( - sqlite3_file *id, - const void *pBuf, - int amt, - sqlite3_int64 offset - ); -static int unixRead( - sqlite3_file *id, - void *pBuf, - int amt, - sqlite3_int64 offset - ); -/* takes the conch by taking a shared lock and read the contents conch, if -** lockPath is non-NULL, the host ID and lock file path must match. A NULL -** lockPath means that the lockPath in the conch file will be used if the -** host IDs match, or a new lock path will be generated automatically -** and written to the conch file. -*/ -static int proxyTakeConch(unixFile *pFile){ - proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; - - if( pCtx->conchHeld>0 ){ - return SQLITE_OK; - }else{ - unixFile *conchFile = pCtx->conchFile; - char testValue[CONCHLEN]; - char conchValue[CONCHLEN]; - char lockPath[MAXPATHLEN]; - char *tLockPath = NULL; - int rc = SQLITE_OK; - int readRc = SQLITE_OK; - int syncPerms = 0; - - OSTRACE4("TAKECONCH %d for %s pid=%d\n", conchFile->h, - (pCtx->lockProxyPath ? pCtx->lockProxyPath : ":auto:"), getpid()); - - rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, SHARED_LOCK); - if( rc==SQLITE_OK ){ - int pError = 0; - memset(testValue, 0, CONCHLEN); // conch is fixed size - rc = proxyGetHostID(testValue, &pError); - if( rc&SQLITE_IOERR==SQLITE_IOERR ){ - pFile->lastErrno = pError; - } - if( pCtx->lockProxyPath ){ - strlcpy(&testValue[HOSTIDLEN], pCtx->lockProxyPath, MAXPATHLEN); - } - } - if( rc!=SQLITE_OK ){ - goto end_takeconch; - } - - readRc = unixRead((sqlite3_file *)conchFile, conchValue, CONCHLEN, 0); - if( readRc!=SQLITE_IOERR_SHORT_READ ){ - int match = 0; - if( readRc!=SQLITE_OK ){ - if( rc&SQLITE_IOERR==SQLITE_IOERR ){ - pFile->lastErrno = conchFile->lastErrno; - } - rc = readRc; - goto end_takeconch; - } - /* if the conch has data compare the contents */ - if( !pCtx->lockProxyPath ){ - /* for auto-named local lock file, just check the host ID and we'll - ** use the local lock file path that's already in there */ - if( !memcmp(testValue, conchValue, HOSTIDLEN) ){ - tLockPath = (char *)&conchValue[HOSTIDLEN]; - goto end_takeconch; - } - }else{ - /* we've got the conch if conchValue matches our path and host ID */ - if( !memcmp(testValue, conchValue, CONCHLEN) ){ - goto end_takeconch; - } - } - }else{ - /* a short read means we're "creating" the conch (even though it could - ** have been user-intervention), if we acquire the exclusive lock, - ** we'll try to match the current on-disk permissions of the database - */ - syncPerms = 1; - } - - /* either conch was emtpy or didn't match */ - if( !pCtx->lockProxyPath ){ - proxyGetLockPath(pCtx->dbPath, lockPath, MAXPATHLEN); - tLockPath = lockPath; - strlcpy(&testValue[HOSTIDLEN], lockPath, MAXPATHLEN); - } - - /* update conch with host and path (this will fail if other process - ** has a shared lock already) */ - rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, EXCLUSIVE_LOCK); - if( rc==SQLITE_OK ){ - rc = unixWrite((sqlite3_file *)conchFile, testValue, CONCHLEN, 0); - if( rc==SQLITE_OK && syncPerms ){ - struct stat buf; - int err = fstat(pFile->h, &buf); - if( err==0 ){ - mode_t mode = buf.st_mode & 0100666; - /* try to match the database file permissions, ignore failure */ -#ifndef SQLITE_PROXY_DEBUG - fchmod(conchFile->h, buf.st_mode); -#else - if( fchmod(conchFile->h, buf.st_mode)!=0 ){ - int code = errno; - fprintf(stderr, "fchmod %o FAILED with %d %s\n", - buf.st_mode, code, strerror(code)); - } else { - fprintf(stderr, "fchmod %o SUCCEDED\n",buf.st_mode); - } - }else{ - int code = errno; - fprintf(stderr, "STAT FAILED[%d] with %d %s\n", - err, code, strerror(code)); -#endif - } - } - } - conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, SHARED_LOCK); - -end_takeconch: - OSTRACE2("TRANSPROXY: CLOSE %d\n", pFile->h); - if( rc==SQLITE_OK && pFile->openFlags ){ - if( pFile->h>=0 ){ -#ifdef STRICT_CLOSE_ERROR - if( close(pFile->h) ){ - pFile->lastErrno = errno; - return SQLITE_IOERR_CLOSE; - } -#else - close(pFile->h); /* silently leak fd if fail */ -#endif - } - pFile->h = -1; - int fd = open(pCtx->dbPath, pFile->openFlags, - SQLITE_DEFAULT_FILE_PERMISSIONS); - OSTRACE2("TRANSPROXY: OPEN %d\n", fd); - if( fd>=0 ){ - pFile->h = fd; - }else{ - rc=SQLITE_CANTOPEN; // SQLITE_BUSY? proxyTakeConch called during locking - } - } - if( rc==SQLITE_OK && !pCtx->lockProxy ){ - char *path = tLockPath ? tLockPath : pCtx->lockProxyPath; - // ACS: Need to make a copy of path sometimes - rc = proxyCreateUnixFile(path, &pCtx->lockProxy); - } - if( rc==SQLITE_OK ){ - pCtx->conchHeld = 1; - - if( tLockPath ){ - pCtx->lockProxyPath = sqlite3DbStrDup(0, tLockPath); - if( pCtx->lockProxy->pMethod == &afpIoMethods ){ - ((afpLockingContext *)pCtx->lockProxy->lockingContext)->dbPath = - pCtx->lockProxyPath; - } - } - } else { - conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK); - } - OSTRACE3("TAKECONCH %d %s\n", conchFile->h, rc==SQLITE_OK?"ok":"failed"); - return rc; - } -} - -/* -** If pFile holds a lock on a conch file, then release that lock. -*/ -static int proxyReleaseConch(unixFile *pFile){ - int rc; /* Subroutine return code */ - proxyLockingContext *pCtx; /* The locking context for the proxy lock */ - unixFile *conchFile; /* Name of the conch file */ - - pCtx = (proxyLockingContext *)pFile->lockingContext; - conchFile = pCtx->conchFile; - OSTRACE4("RELEASECONCH %d for %s pid=%d\n", conchFile->h, - (pCtx->lockProxyPath ? pCtx->lockProxyPath : ":auto:"), - getpid()); - pCtx->conchHeld = 0; - rc = conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK); - OSTRACE3("RELEASECONCH %d %s\n", conchFile->h, - (rc==SQLITE_OK ? "ok" : "failed")); - return rc; -} - -/* -** Given the name of a database file, compute the name of its conch file. -** Store the conch filename in memory obtained from sqlite3_malloc(). -** Make *pConchPath point to the new name. Return SQLITE_OK on success -** or SQLITE_NOMEM if unable to obtain memory. -** -** The caller is responsible for ensuring that the allocated memory -** space is eventually freed. -** -** *pConchPath is set to NULL if a memory allocation error occurs. -*/ -static int proxyCreateConchPathname(char *dbPath, char **pConchPath){ - int i; /* Loop counter */ - int len = strlen(dbPath); /* Length of database filename - dbPath */ - char *conchPath; /* buffer in which to construct conch name */ - - /* Allocate space for the conch filename and initialize the name to - ** the name of the original database file. */ - *pConchPath = conchPath = (char *)sqlite3_malloc(len + 8); - if( conchPath==0 ){ - return SQLITE_NOMEM; - } - memcpy(conchPath, dbPath, len+1); - - /* now insert a "." before the last / character */ - for( i=(len-1); i>=0; i-- ){ - if( conchPath[i]=='/' ){ - i++; - break; - } - } - conchPath[i]='.'; - while ( i<len ){ - conchPath[i+1]=dbPath[i]; - i++; - } - - /* append the "-conch" suffix to the file */ - memcpy(&conchPath[i+1], "-conch", 7); - assert( strlen(conchPath) == len+7 ); - - return SQLITE_OK; -} - - -/* Takes a fully configured proxy locking-style unix file and switches -** the local lock file path -*/ -static int switchLockProxyPath(unixFile *pFile, const char *path) { - proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext; - char *oldPath = pCtx->lockProxyPath; - int taken = 0; - int rc = SQLITE_OK; - - if( pFile->locktype!=NO_LOCK ){ - return SQLITE_BUSY; - } - - /* nothing to do if the path is NULL, :auto: or matches the existing path */ - if( !path || path[0]=='\0' || !strcmp(path, ":auto:") || - (oldPath && !strncmp(oldPath, path, MAXPATHLEN)) ){ - return SQLITE_OK; - }else{ - unixFile *lockProxy = pCtx->lockProxy; - pCtx->lockProxy=NULL; - pCtx->conchHeld = 0; - if( lockProxy!=NULL ){ - rc=lockProxy->pMethod->xClose((sqlite3_file *)lockProxy); - if( rc ) return rc; - sqlite3_free(lockProxy); - } - sqlite3_free(oldPath); - pCtx->lockProxyPath = sqlite3DbStrDup(0, path); - } - - return rc; -} - -static const sqlite3_io_methods dotlockIoMethods; -/* -** pFile is a file that has been opened by a prior xOpen call. dbPath -** is a string buffer at least MAXPATHLEN+1 characters in size. -** -** This routine find the filename associated with pFile and writes it -** int dbPath. -*/ -static int proxyGetDbPathForUnixFile(unixFile *pFile, char *dbPath){ -#if defined(__DARWIN__) - if( pFile->pMethod == &afpIoMethods ){ - /* afp style keeps a reference to the db path in the filePath field - ** of the struct */ - assert( strlen((char*)pFile->lockingContext)<=MAXPATHLEN ); - strcpy(dbPath, ((afpLockingContext *)pFile->lockingContext)->dbPath); - }else -#endif - if( pFile->pMethod == &dotlockIoMethods ){ - /* dot lock style uses the locking context to store the dot lock - ** file path */ - int len = strlen((char *)pFile->lockingContext) - strlen(DOTLOCK_SUFFIX); - memcpy(dbPath, (char *)pFile->lockingContext, len + 1); - }else{ - /* all other styles use the locking context to store the db file path */ - assert( strlen((char*)pFile->lockingContext)<=MAXPATHLEN ); - strcpy(dbPath, (char *)pFile->lockingContext); - } - return SQLITE_OK; -} -static const sqlite3_io_methods proxyIoMethods; -/* -** Takes an already filled in unix file and alters it so all file locking -** will be performed on the local proxy lock file. The following fields -** are preserved in the locking context so that they can be restored and -** the unix structure properly cleaned up at close time: -** ->lockingContext -** ->pMethod -*/ -static int transformUnixFileForLockProxy(unixFile *pFile, const char *path) { - proxyLockingContext *pCtx; - char dbPath[MAXPATHLEN+1]; /* Name of the database file */ - char *lockPath=NULL; - int rc = SQLITE_OK; - - if( pFile->locktype!=NO_LOCK ){ - return SQLITE_BUSY; - } - proxyGetDbPathForUnixFile(pFile, dbPath); - if( !path || path[0]=='\0' || !strcmp(path, ":auto:") ){ - lockPath=NULL; - }else{ - lockPath=(char *)path; - } - - OSTRACE4("TRANSPROXY %d for %s pid=%d\n", pFile->h, - (lockPath ? lockPath : ":auto:"), getpid()); - - pCtx = sqlite3_malloc( sizeof(*pCtx) ); - if( pCtx==0 ){ - return SQLITE_NOMEM; - } - memset(pCtx, 0, sizeof(*pCtx)); - - rc = proxyCreateConchPathname(dbPath, &pCtx->conchFilePath); - if( rc==SQLITE_OK ){ - rc = proxyCreateUnixFile(pCtx->conchFilePath, &pCtx->conchFile); - } - if( rc==SQLITE_OK && lockPath ){ - pCtx->lockProxyPath = sqlite3DbStrDup(0, lockPath); - } - -end_transform_file: - if( rc==SQLITE_OK ){ - /* all memory is allocated, proxys are created and assigned, - ** switch the locking context and pMethod then return. - */ - pCtx->dbPath = sqlite3DbStrDup(0, dbPath); - pCtx->oldLockingContext = pFile->lockingContext; - pFile->lockingContext = pCtx; - pCtx->pOldMethod = pFile->pMethod; - pFile->pMethod = &proxyIoMethods; - }else{ - if( pCtx->conchFile ){ - rc = pCtx->conchFile->pMethod->xClose((sqlite3_file *)pCtx->conchFile); - if( rc ) return rc; - sqlite3_free(pCtx->conchFile); - } - sqlite3_free(pCtx->conchFilePath); - sqlite3_free(pCtx); - } - OSTRACE3("TRANSPROXY %d %s\n", pFile->h, - (rc==SQLITE_OK ? "ok" : "failed")); - return rc; -} - -/* -** Within this division (the proxying locking implementation) the procedures -** above this point are all utilities. The lock-related methods of the -** proxy-locking sqlite3_io_method object follow. -*/ - - -/* -** 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 proxyCheckReservedLock(sqlite3_file *id, int *pResOut) { - unixFile *pFile = (unixFile*)id; - int rc = proxyTakeConch(pFile); - if( rc==SQLITE_OK ){ - proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; - unixFile *proxy = pCtx->lockProxy; - return proxy->pMethod->xCheckReservedLock((sqlite3_file*)proxy, pResOut); - } - 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 proxyLock(sqlite3_file *id, int locktype) { - unixFile *pFile = (unixFile*)id; - int rc = proxyTakeConch(pFile); - if( rc==SQLITE_OK ){ - proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; - unixFile *proxy = pCtx->lockProxy; - rc = proxy->pMethod->xLock((sqlite3_file*)proxy, locktype); - pFile->locktype = proxy->locktype; - } - 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 proxyUnlock(sqlite3_file *id, int locktype) { - unixFile *pFile = (unixFile*)id; - int rc = proxyTakeConch(pFile); - if( rc==SQLITE_OK ){ - proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; - unixFile *proxy = pCtx->lockProxy; - rc = proxy->pMethod->xUnlock((sqlite3_file*)proxy, locktype); - pFile->locktype = proxy->locktype; - } - return rc; -} - -/* -** Close a file that uses proxy locks. -*/ -static int proxyClose(sqlite3_file *id) { - if( id ){ - unixFile *pFile = (unixFile*)id; - proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; - unixFile *lockProxy = pCtx->lockProxy; - unixFile *conchFile = pCtx->conchFile; - int rc = SQLITE_OK; - - if( lockProxy ){ - rc = lockProxy->pMethod->xUnlock((sqlite3_file*)lockProxy, NO_LOCK); - if( rc ) return rc; - rc = lockProxy->pMethod->xClose((sqlite3_file*)lockProxy); - if( rc ) return rc; - sqlite3_free(lockProxy); - pCtx->lockProxy = 0; - } - if( conchFile ){ - if( pCtx->conchHeld ){ - rc = proxyReleaseConch(pFile); - if( rc ) return rc; - } - rc = conchFile->pMethod->xClose((sqlite3_file*)conchFile); - if( rc ) return rc; - sqlite3_free(conchFile); - } - sqlite3_free(pCtx->lockProxyPath); - sqlite3_free(pCtx->conchFilePath); - sqlite3_free(pCtx->dbPath); - /* restore the original locking context and pMethod then close it */ - pFile->lockingContext = pCtx->oldLockingContext; - pFile->pMethod = pCtx->pOldMethod; - sqlite3_free(pCtx); - return pFile->pMethod->xClose(id); - } - return SQLITE_OK; -} - - - -#endif /* defined(__DARWIN__) && SQLITE_ENABLE_LOCKING_STYLE */ -/* -** The proxy locking style is intended for use with AFP filesystems. -** And since AFP is only supported on MacOSX, the proxy locking is also -** restricted to MacOSX. -** -** -******************* End of the proxy lock implementation ********************** -******************************************************************************/ - /****************************************************************************** **************** Non-locking sqlite3_file methods ***************************** @@ -3833,6 +2939,12 @@ static int unixFileSize(sqlite3_file *id, i64 *pSize){ return SQLITE_OK; } +/* +** Handler for proxy-locking file-control verbs. Defined below in the +** proxying locking division. +*/ +static int proxyFileControl(sqlite3_file*,int,void*); + /* ** Information and control of an open file handle. @@ -3848,52 +2960,9 @@ static int unixFileControl(sqlite3_file *id, int op, void *pArg){ return SQLITE_OK; } #if SQLITE_ENABLE_LOCKING_STYLE && defined(__DARWIN__) + case SQLITE_SET_LOCKPROXYFILE: case SQLITE_GET_LOCKPROXYFILE: { - unixFile *pFile = (unixFile*)id; - if( pFile->pMethod == &proxyIoMethods ){ - proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext; - proxyTakeConch(pFile); - if( pCtx->lockProxyPath ){ - *(const char **)pArg = pCtx->lockProxyPath; - }else{ - *(const char **)pArg = ":auto: (not held)"; - } - } else { - *(const char **)pArg = NULL; - } - return SQLITE_OK; - } - case SQLITE_SET_LOCKPROXYFILE: { - unixFile *pFile = (unixFile*)id; - int rc = SQLITE_OK; - int isProxyStyle = (pFile->pMethod == &proxyIoMethods); - if( pArg==NULL || (const char *)pArg==0 ){ - if( isProxyStyle ){ - /* turn off proxy locking - not supported */ - rc = SQLITE_ERROR /*SQLITE_PROTOCOL? SQLITE_MISUSE?*/; - }else{ - /* turn off proxy locking - already off - NOOP */ - rc = SQLITE_OK; - } - }else{ - const char *proxyPath = (const char *)pArg; - if( isProxyStyle ){ - proxyLockingContext *pCtx = - (proxyLockingContext*)pFile->lockingContext; - if( !strcmp(pArg, ":auto:") - || (pCtx->lockProxyPath && - !strncmp(pCtx->lockProxyPath, proxyPath, MAXPATHLEN)) - ){ - rc = SQLITE_OK; - }else{ - rc = switchLockProxyPath(pFile, proxyPath); - } - }else{ - /* turn on proxy file locking */ - rc = transformUnixFileForLockProxy(pFile, proxyPath); - } - } - return rc; + return proxyFileControl(id,op,pArg); } #endif /* SQLITE_ENABLE_LOCKING_STYLE && defined(__DARWIN__) */ } @@ -4033,6 +3102,22 @@ IOMETHODS( afpUnlock, /* xUnlock method */ afpCheckReservedLock /* xCheckReservedLock method */ ); +#endif + +/* +** The proxy locking method is a "super-method" in the sense that it +** opens secondary file descriptors for the conch and lock files and +** it uses proxy, dot-file, AFP, and flock() locking methods on those +** secondary files. For this reason, the division that implements +** proxy locking is located much further down in the file. But we need +** to go ahead and define the sqlite3_io_methods and finder function +** for proxy locking here. So we forward declare the I/O methods. +*/ +#if defined(__DARWIN__) && SQLITE_ENABLE_LOCKING_STYLE +static int proxyClose(sqlite3_file*); +static int proxyLock(sqlite3_file*, int); +static int proxyUnlock(sqlite3_file*, int); +static int proxyCheckReservedLock(sqlite3_file*, int*); IOMETHODS( proxyIoFinder, /* Finder function name */ proxyIoMethods, /* sqlite3_io_methods object name */ @@ -4139,19 +3224,13 @@ static int fillInUnixFile( assert( pNew->pLock==NULL ); assert( pNew->pOpen==NULL ); - /* Parameter isDelete is only used on vxworks. Parameter pVfs is only - ** used if ENABLE_LOCKING_STYLE is defined. Express this explicitly - ** here to prevent compiler warnings about unused parameters. + /* Parameter isDelete is only used on vxworks. + ** Express this explicitly here to prevent compiler warnings + ** about unused parameters. */ #if !OS_VXWORKS UNUSED_PARAMETER(isDelete); #endif -#if !SQLITE_ENABLE_LOCKING_STYLE - UNUSED_PARAMETER(pVfs); -#endif -#if !OS_VXWORKS && !SQLITE_ENABLE_LOCKING_STYLE - UNUSED_PARAMETER(zFilename); -#endif OSTRACE3("OPEN %-3d %s\n", h, zFilename); pNew->h = h; @@ -4524,7 +3603,7 @@ static int unixOpen( if( useProxy ){ rc = fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock, isDelete); if( rc==SQLITE_OK ){ - rc = transformUnixFileForLockProxy((unixFile*)pFile, ":auto:"); + rc = proxyTransformUnixFile((unixFile*)pFile, ":auto:"); } return rc; } @@ -4816,6 +3895,935 @@ static int unixGetLastError(sqlite3_vfs *NotUsed, int NotUsed2, char *NotUsed3){ ************************ End of sqlite3_vfs methods *************************** ******************************************************************************/ +/****************************************************************************** +************************** Begin Proxy Locking ******************************** +** +** Proxy locking is a "uber-locking-method" in this sense: It uses the +** other locking methods on secondary lock files. Proxy locking is a +** meta-layer over top of the primitive locking implemented above. For +** this reason, the division that implements of proxy locking is deferred +** until late in the file (here) after all of the other I/O methods have +** been defined - so that the primitive locking methods are available +** as services to help with the implementation of proxy locking. +** +**** +** +** The default locking schemes in SQLite use byte-range locks on the +** database file to coordinate safe, concurrent access by multiple readers +** and writers [http://sqlite.org/lockingv3.html]. The five file locking +** states (UNLOCKED, PENDING, SHARED, RESERVED, EXCLUSIVE) are implemented +** as POSIX read & write locks over fixed set of locations (via fsctl), +** on AFP and SMB only exclusive byte-range locks are available via fsctl +** with _IOWR('z', 23, struct ByteRangeLockPB2) to track the same 5 states. +** To simulate a F_RDLCK on the shared range, on AFP a randomly selected +** address in the shared range is taken for a SHARED lock, the entire +** shared range is taken for an EXCLUSIVE lock): +** +** PENDING_BYTE 0x40000000 +** RESERVED_BYTE 0x40000001 +** SHARED_RANGE 0x40000002 -> 0x40000200 +** +** This works well on the local file system, but shows a nearly 100x +** slowdown in read performance on AFP because the AFP client disables +** the read cache when byte-range locks are present. Enabling the read +** cache exposes a cache coherency problem that is present on all OS X +** supported network file systems. NFS and AFP both observe the +** close-to-open semantics for ensuring cache coherency +** [http://nfs.sourceforge.net/#faq_a8], which does not effectively +** address the requirements for concurrent database access by multiple +** readers and writers +** [http://www.nabble.com/SQLite-on-NFS-cache-coherency-td15655701.html]. +** +** To address the performance and cache coherency issues, proxy file locking +** changes the way database access is controlled by limiting access to a +** single host at a time and moving file locks off of the database file +** and onto a proxy file on the local file system. +** +** +** Using proxy locks +** ----------------- +** +** C APIs +** +** sqlite3_file_control(db, dbname, SQLITE_SET_LOCKPROXYFILE, +** <proxy_path> | ":auto:"); +** sqlite3_file_control(db, dbname, SQLITE_GET_LOCKPROXYFILE, &<proxy_path>); +** +** +** SQL pragmas +** +** PRAGMA [database.]lock_proxy_file=<proxy_path> | :auto: +** PRAGMA [database.]lock_proxy_file +** +** Specifying ":auto:" means that if there is a conch file with a matching +** host ID in it, the proxy path in the conch file will be used, otherwise +** a proxy path based on the user's temp dir +** (via confstr(_CS_DARWIN_USER_TEMP_DIR,...)) will be used and the +** actual proxy file name is generated from the name and path of the +** database file. For example: +** +** For database path "/Users/me/foo.db" +** The lock path will be "<tmpdir>/sqliteplocks/_Users_me_foo.db:auto:") +** +** Once a lock proxy is configured for a database connection, it can not +** be removed, however it may be switched to a different proxy path via +** the above APIs (assuming the conch file is not being held by another +** connection or process). +** +** +** How proxy locking works +** ----------------------- +** +** Proxy file locking relies primarily on two new supporting files: +** +** * conch file to limit access to the database file to a single host +** at a time +** +** * proxy file to act as a proxy for the advisory locks normally +** taken on the database +** +** The conch file - to use a proxy file, sqlite must first "hold the conch" +** by taking an sqlite-style shared lock on the conch file, reading the +** contents and comparing the host's unique host ID (see below) and lock +** proxy path against the values stored in the conch. The conch file is +** stored in the same directory as the database file and the file name +** is patterned after the database file name as ".<databasename>-conch". +** If the conch file does not exist, or it's contents do not match the +** host ID and/or proxy path, then the lock is escalated to an exclusive +** lock and the conch file contents is updated with the host ID and proxy +** path and the lock is downgraded to a shared lock again. If the conch +** is held by another process (with a shared lock), the exclusive lock +** will fail and SQLITE_BUSY is returned. +** +** The proxy file - a single-byte file used for all advisory file locks +** normally taken on the database file. This allows for safe sharing +** of the database file for multiple readers and writers on the same +** host (the conch ensures that they all use the same local lock file). +** +** There is a third file - the host ID file - used as a persistent record +** of a unique identifier for the host, a 128-byte unique host id file +** in the path defined by the HOSTIDPATH macro (default value is +** /Library/Caches/.com.apple.sqliteConchHostId). +** +** Requesting the lock proxy does not immediately take the conch, it is +** only taken when the first request to lock database file is made. +** This matches the semantics of the traditional locking behavior, where +** opening a connection to a database file does not take a lock on it. +** The shared lock and an open file descriptor are maintained until +** the connection to the database is closed. +** +** The proxy file and the lock file are never deleted so they only need +** to be created the first time they are used. +** +** Configuration options +** --------------------- +** +** SQLITE_PREFER_PROXY_LOCKING +** +** Database files accessed on non-local file systems are +** automatically configured for proxy locking, lock files are +** named automatically using the same logic as +** PRAGMA lock_proxy_file=":auto:" +** +** SQLITE_PROXY_DEBUG +** +** Enables the logging of error messages during host id file +** retrieval and creation +** +** HOSTIDPATH +** +** Overrides the default host ID file path location +** +** LOCKPROXYDIR +** +** Overrides the default directory used for lock proxy files that +** are named automatically via the ":auto:" setting +** +** SQLITE_DEFAULT_PROXYDIR_PERMISSIONS +** +** Permissions to use when creating a directory for storing the +** lock proxy files, only used when LOCKPROXYDIR is not set. +** +** +** As mentioned above, when compiled with SQLITE_PREFER_PROXY_LOCKING, +** setting the environment variable SQLITE_FORCE_PROXY_LOCKING to 1 will +** force proxy locking to be used for every database file opened, and 0 +** will force automatic proxy locking to be disabled for all database +** files (explicity calling the SQLITE_SET_LOCKPROXYFILE pragma or +** sqlite_file_control API is not affected by SQLITE_FORCE_PROXY_LOCKING). +*/ + +/* +** Proxy locking is only available on MacOSX +*/ +#if defined(__DARWIN__) && SQLITE_ENABLE_LOCKING_STYLE + +#ifdef SQLITE_TEST +/* simulate multiple hosts by creating unique hostid file paths */ +int sqlite3_hostid_num = 0; +#endif + +/* +** The proxyLockingContext has the path and file structures for the remote +** and local proxy files in it +*/ +typedef struct proxyLockingContext proxyLockingContext; +struct proxyLockingContext { + unixFile *conchFile; /* Open conch file */ + char *conchFilePath; /* Name of the conch file */ + unixFile *lockProxy; /* Open proxy lock file */ + char *lockProxyPath; /* Name of the proxy lock file */ + char *dbPath; /* Name of the open file */ + int conchHeld; /* True if the conch is currently held */ + void *oldLockingContext; /* Original lockingcontext to restore on close */ + sqlite3_io_methods const *pOldMethod; /* Original I/O methods for close */ +}; + +/* HOSTIDLEN and CONCHLEN both include space for the string +** terminating nul +*/ +#define HOSTIDLEN 128 +#define CONCHLEN (MAXPATHLEN+HOSTIDLEN+1) +#ifndef HOSTIDPATH +# define HOSTIDPATH "/Library/Caches/.com.apple.sqliteConchHostId" +#endif + +/* basically a copy of unixRandomness with different +** test behavior built in */ +static int proxyGenerateHostID(char *pHostID){ + int pid, fd, len; + unsigned char *key = (unsigned char *)pHostID; + + memset(key, 0, HOSTIDLEN); + len = 0; + fd = open("/dev/urandom", O_RDONLY); + if( fd>=0 ){ + len = read(fd, key, HOSTIDLEN); + close(fd); /* silently leak the fd if it fails */ + } + if( len < HOSTIDLEN ){ + time_t t; + time(&t); + memcpy(key, &t, sizeof(t)); + pid = getpid(); + memcpy(&key[sizeof(t)], &pid, sizeof(pid)); + } + +#ifdef MAKE_PRETTY_HOSTID + { + int i; + /* filter the bytes into printable ascii characters and NUL terminate */ + key[(HOSTIDLEN-1)] = 0x00; + for( i=0; i<(HOSTIDLEN-1); i++ ){ + unsigned char pa = key[i]&0x7F; + if( pa<0x20 ){ + key[i] = (key[i]&0x80 == 0x80) ? pa+0x40 : pa+0x20; + }else if( pa==0x7F ){ + key[i] = (key[i]&0x80 == 0x80) ? pa=0x20 : pa+0x7E; + } + } + } +#endif + return SQLITE_OK; +} + +/* writes the host id path to path, path should be an pre-allocated buffer +** with enough space for a path +*/ +static void proxyGetHostIDPath(char *path, size_t len){ + strlcpy(path, HOSTIDPATH, len); +#ifdef SQLITE_TEST + if( sqlite3_hostid_num>0 ){ + char suffix[2] = "1"; + suffix[0] = suffix[0] + sqlite3_hostid_num; + strlcat(path, suffix, len); + } +#endif + OSTRACE3("GETHOSTIDPATH %s pid=%d\n", path, getpid()); +} + +/* get the host ID from a sqlite hostid file stored in the +** user-specific tmp directory, create the ID if it's not there already +*/ +static int proxyGetHostID(char *pHostID, int *pError){ + int fd; + char path[MAXPATHLEN]; + size_t len; + int rc=SQLITE_OK; + + proxyGetHostIDPath(path, MAXPATHLEN); + /* try to create the host ID file, if it already exists read the contents */ + fd = open(path, O_CREAT|O_WRONLY|O_EXCL, 0644); + if( fd<0 ){ + int err=errno; + + if( err!=EEXIST ){ +#ifdef SQLITE_PROXY_DEBUG /* set the sqlite error message instead */ + fprintf(stderr, "sqlite error creating host ID file %s: %s\n", + path, strerror(err)); +#endif + return SQLITE_PERM; + } + /* couldn't create the file, read it instead */ + fd = open(path, O_RDONLY|O_EXCL); + if( fd<0 ){ +#ifdef SQLITE_PROXY_DEBUG /* set the sqlite error message instead */ + int err = errno; + fprintf(stderr, "sqlite error opening host ID file %s: %s\n", + path, strerror(err)); +#endif + return SQLITE_PERM; + } + len = pread(fd, pHostID, HOSTIDLEN, 0); + if( len<0 ){ + *pError = errno; + rc = SQLITE_IOERR_READ; + }else if( len<HOSTIDLEN ){ + *pError = 0; + rc = SQLITE_IOERR_SHORT_READ; + } + close(fd); /* silently leak the fd if it fails */ + OSTRACE3("GETHOSTID read %s pid=%d\n", pHostID, getpid()); + return rc; + }else{ + /* we're creating the host ID file (use a random string of bytes) */ + proxyGenerateHostID(pHostID); + len = pwrite(fd, pHostID, HOSTIDLEN, 0); + if( len<0 ){ + *pError = errno; + rc = SQLITE_IOERR_WRITE; + }else if( len<HOSTIDLEN ){ + *pError = 0; + rc = SQLITE_IOERR_WRITE; + } + close(fd); /* silently leak the fd if it fails */ + OSTRACE3("GETHOSTID wrote %s pid=%d\n", pHostID, getpid()); + return rc; + } +} + +static int proxyGetLockPath(const char *dbPath, char *lPath, size_t maxLen){ + int len; + int dbLen; + int i; + +#ifdef LOCKPROXYDIR + len = strlcpy(lPath, LOCKPROXYDIR, maxLen); +#else +# ifdef _CS_DARWIN_USER_TEMP_DIR + { + confstr(_CS_DARWIN_USER_TEMP_DIR, lPath, maxLen); + len = strlcat(lPath, "sqliteplocks", maxLen); + if( mkdir(lPath, SQLITE_DEFAULT_PROXYDIR_PERMISSIONS) ){ + /* if mkdir fails, handle as lock file creation failure */ + int err = errno; +# ifdef SQLITE_DEBUG + if( err!=EEXIST ){ + fprintf(stderr, "proxyGetLockPath: mkdir(%s,0%o) error %d %s\n", lPath, + SQLITE_DEFAULT_PROXYDIR_PERMISSIONS, err, strerror(err)); + } +# endif + }else{ + OSTRACE3("GETLOCKPATH mkdir %s pid=%d\n", lPath, getpid()); + } + + } +# else + len = strlcpy(lPath, "/tmp/", maxLen); +# endif +#endif + + if( lPath[len-1]!='/' ){ + len = strlcat(lPath, "/", maxLen); + } + + /* transform the db path to a unique cache name */ + dbLen = strlen(dbPath); + for( i=0; i<dbLen && (i+len+7)<maxLen; i++){ + char c = dbPath[i]; + lPath[i+len] = (c=='/')?'_':c; + } + lPath[i+len]='\0'; + strlcat(lPath, ":auto:", maxLen); + return SQLITE_OK; +} + +/* +** Create a new VFS file descriptor (stored in memory obtained from +** sqlite3_malloc) and open the file named "path" in the file descriptor. +** +** The caller is responsible not only for closing the file descriptor +** but also for freeing the memory associated with the file descriptor. +*/ +static int proxyCreateUnixFile(const char *path, unixFile **ppFile) { + int fd; + int dirfd = -1; + unixFile *pNew; + int rc = SQLITE_OK; + sqlite3_vfs dummyVfs; + + fd = open(path, O_RDWR | O_CREAT, SQLITE_DEFAULT_FILE_PERMISSIONS); + if( fd<0 ){ + return SQLITE_CANTOPEN; + } + + pNew = (unixFile *)sqlite3_malloc(sizeof(unixFile)); + if( pNew==NULL ){ + rc = SQLITE_NOMEM; + goto end_create_proxy; + } + memset(pNew, 0, sizeof(unixFile)); + + dummyVfs.pAppData = (void*)autolockIoFinder; + rc = fillInUnixFile(&dummyVfs, fd, dirfd, (sqlite3_file*)pNew, path, 0, 0); + if( rc==SQLITE_OK ){ + *ppFile = pNew; + return SQLITE_OK; + } +end_create_proxy: + close(fd); /* silently leak fd if error, we're already in error */ + sqlite3_free(pNew); + return rc; +} + +/* takes the conch by taking a shared lock and read the contents conch, if +** lockPath is non-NULL, the host ID and lock file path must match. A NULL +** lockPath means that the lockPath in the conch file will be used if the +** host IDs match, or a new lock path will be generated automatically +** and written to the conch file. +*/ +static int proxyTakeConch(unixFile *pFile){ + proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; + + if( pCtx->conchHeld>0 ){ + return SQLITE_OK; + }else{ + unixFile *conchFile = pCtx->conchFile; + char testValue[CONCHLEN]; + char conchValue[CONCHLEN]; + char lockPath[MAXPATHLEN]; + char *tLockPath = NULL; + int rc = SQLITE_OK; + int readRc = SQLITE_OK; + int syncPerms = 0; + + OSTRACE4("TAKECONCH %d for %s pid=%d\n", conchFile->h, + (pCtx->lockProxyPath ? pCtx->lockProxyPath : ":auto:"), getpid()); + + rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, SHARED_LOCK); + if( rc==SQLITE_OK ){ + int pError = 0; + memset(testValue, 0, CONCHLEN); // conch is fixed size + rc = proxyGetHostID(testValue, &pError); + if( (rc&0xff)==SQLITE_IOERR ){ + pFile->lastErrno = pError; + } + if( pCtx->lockProxyPath ){ + strlcpy(&testValue[HOSTIDLEN], pCtx->lockProxyPath, MAXPATHLEN); + } + } + if( rc!=SQLITE_OK ){ + goto end_takeconch; + } + + readRc = unixRead((sqlite3_file *)conchFile, conchValue, CONCHLEN, 0); + if( readRc!=SQLITE_IOERR_SHORT_READ ){ + if( readRc!=SQLITE_OK ){ + if( (rc&0xff)==SQLITE_IOERR ){ + pFile->lastErrno = conchFile->lastErrno; + } + rc = readRc; + goto end_takeconch; + } + /* if the conch has data compare the contents */ + if( !pCtx->lockProxyPath ){ + /* for auto-named local lock file, just check the host ID and we'll + ** use the local lock file path that's already in there */ + if( !memcmp(testValue, conchValue, HOSTIDLEN) ){ + tLockPath = (char *)&conchValue[HOSTIDLEN]; + goto end_takeconch; + } + }else{ + /* we've got the conch if conchValue matches our path and host ID */ + if( !memcmp(testValue, conchValue, CONCHLEN) ){ + goto end_takeconch; + } + } + }else{ + /* a short read means we're "creating" the conch (even though it could + ** have been user-intervention), if we acquire the exclusive lock, + ** we'll try to match the current on-disk permissions of the database + */ + syncPerms = 1; + } + + /* either conch was emtpy or didn't match */ + if( !pCtx->lockProxyPath ){ + proxyGetLockPath(pCtx->dbPath, lockPath, MAXPATHLEN); + tLockPath = lockPath; + strlcpy(&testValue[HOSTIDLEN], lockPath, MAXPATHLEN); + } + + /* update conch with host and path (this will fail if other process + ** has a shared lock already) */ + rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, EXCLUSIVE_LOCK); + if( rc==SQLITE_OK ){ + rc = unixWrite((sqlite3_file *)conchFile, testValue, CONCHLEN, 0); + if( rc==SQLITE_OK && syncPerms ){ + struct stat buf; + int err = fstat(pFile->h, &buf); + if( err==0 ){ + /* try to match the database file permissions, ignore failure */ +#ifndef SQLITE_PROXY_DEBUG + fchmod(conchFile->h, buf.st_mode); +#else + if( fchmod(conchFile->h, buf.st_mode)!=0 ){ + int code = errno; + fprintf(stderr, "fchmod %o FAILED with %d %s\n", + buf.st_mode, code, strerror(code)); + } else { + fprintf(stderr, "fchmod %o SUCCEDED\n",buf.st_mode); + } + }else{ + int code = errno; + fprintf(stderr, "STAT FAILED[%d] with %d %s\n", + err, code, strerror(code)); +#endif + } + } + } + conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, SHARED_LOCK); + +end_takeconch: + OSTRACE2("TRANSPROXY: CLOSE %d\n", pFile->h); + if( rc==SQLITE_OK && pFile->openFlags ){ + if( pFile->h>=0 ){ +#ifdef STRICT_CLOSE_ERROR + if( close(pFile->h) ){ + pFile->lastErrno = errno; + return SQLITE_IOERR_CLOSE; + } +#else + close(pFile->h); /* silently leak fd if fail */ +#endif + } + pFile->h = -1; + int fd = open(pCtx->dbPath, pFile->openFlags, + SQLITE_DEFAULT_FILE_PERMISSIONS); + OSTRACE2("TRANSPROXY: OPEN %d\n", fd); + if( fd>=0 ){ + pFile->h = fd; + }else{ + rc=SQLITE_CANTOPEN; // SQLITE_BUSY? proxyTakeConch called during locking + } + } + if( rc==SQLITE_OK && !pCtx->lockProxy ){ + char *path = tLockPath ? tLockPath : pCtx->lockProxyPath; + // ACS: Need to make a copy of path sometimes + rc = proxyCreateUnixFile(path, &pCtx->lockProxy); + } + if( rc==SQLITE_OK ){ + pCtx->conchHeld = 1; + + if( tLockPath ){ + pCtx->lockProxyPath = sqlite3DbStrDup(0, tLockPath); + if( pCtx->lockProxy->pMethod == &afpIoMethods ){ + ((afpLockingContext *)pCtx->lockProxy->lockingContext)->dbPath = + pCtx->lockProxyPath; + } + } + } else { + conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK); + } + OSTRACE3("TAKECONCH %d %s\n", conchFile->h, rc==SQLITE_OK?"ok":"failed"); + return rc; + } +} + +/* +** If pFile holds a lock on a conch file, then release that lock. +*/ +static int proxyReleaseConch(unixFile *pFile){ + int rc; /* Subroutine return code */ + proxyLockingContext *pCtx; /* The locking context for the proxy lock */ + unixFile *conchFile; /* Name of the conch file */ + + pCtx = (proxyLockingContext *)pFile->lockingContext; + conchFile = pCtx->conchFile; + OSTRACE4("RELEASECONCH %d for %s pid=%d\n", conchFile->h, + (pCtx->lockProxyPath ? pCtx->lockProxyPath : ":auto:"), + getpid()); + pCtx->conchHeld = 0; + rc = conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK); + OSTRACE3("RELEASECONCH %d %s\n", conchFile->h, + (rc==SQLITE_OK ? "ok" : "failed")); + return rc; +} + +/* +** Given the name of a database file, compute the name of its conch file. +** Store the conch filename in memory obtained from sqlite3_malloc(). +** Make *pConchPath point to the new name. Return SQLITE_OK on success +** or SQLITE_NOMEM if unable to obtain memory. +** +** The caller is responsible for ensuring that the allocated memory +** space is eventually freed. +** +** *pConchPath is set to NULL if a memory allocation error occurs. +*/ +static int proxyCreateConchPathname(char *dbPath, char **pConchPath){ + int i; /* Loop counter */ + int len = strlen(dbPath); /* Length of database filename - dbPath */ + char *conchPath; /* buffer in which to construct conch name */ + + /* Allocate space for the conch filename and initialize the name to + ** the name of the original database file. */ + *pConchPath = conchPath = (char *)sqlite3_malloc(len + 8); + if( conchPath==0 ){ + return SQLITE_NOMEM; + } + memcpy(conchPath, dbPath, len+1); + + /* now insert a "." before the last / character */ + for( i=(len-1); i>=0; i-- ){ + if( conchPath[i]=='/' ){ + i++; + break; + } + } + conchPath[i]='.'; + while ( i<len ){ + conchPath[i+1]=dbPath[i]; + i++; + } + + /* append the "-conch" suffix to the file */ + memcpy(&conchPath[i+1], "-conch", 7); + assert( strlen(conchPath) == len+7 ); + + return SQLITE_OK; +} + + +/* Takes a fully configured proxy locking-style unix file and switches +** the local lock file path +*/ +static int switchLockProxyPath(unixFile *pFile, const char *path) { + proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext; + char *oldPath = pCtx->lockProxyPath; + int rc = SQLITE_OK; + + if( pFile->locktype!=NO_LOCK ){ + return SQLITE_BUSY; + } + + /* nothing to do if the path is NULL, :auto: or matches the existing path */ + if( !path || path[0]=='\0' || !strcmp(path, ":auto:") || + (oldPath && !strncmp(oldPath, path, MAXPATHLEN)) ){ + return SQLITE_OK; + }else{ + unixFile *lockProxy = pCtx->lockProxy; + pCtx->lockProxy=NULL; + pCtx->conchHeld = 0; + if( lockProxy!=NULL ){ + rc=lockProxy->pMethod->xClose((sqlite3_file *)lockProxy); + if( rc ) return rc; + sqlite3_free(lockProxy); + } + sqlite3_free(oldPath); + pCtx->lockProxyPath = sqlite3DbStrDup(0, path); + } + + return rc; +} + +/* +** pFile is a file that has been opened by a prior xOpen call. dbPath +** is a string buffer at least MAXPATHLEN+1 characters in size. +** +** This routine find the filename associated with pFile and writes it +** int dbPath. +*/ +static int proxyGetDbPathForUnixFile(unixFile *pFile, char *dbPath){ +#if defined(__DARWIN__) + if( pFile->pMethod == &afpIoMethods ){ + /* afp style keeps a reference to the db path in the filePath field + ** of the struct */ + assert( strlen((char*)pFile->lockingContext)<=MAXPATHLEN ); + strcpy(dbPath, ((afpLockingContext *)pFile->lockingContext)->dbPath); + }else +#endif + if( pFile->pMethod == &dotlockIoMethods ){ + /* dot lock style uses the locking context to store the dot lock + ** file path */ + int len = strlen((char *)pFile->lockingContext) - strlen(DOTLOCK_SUFFIX); + memcpy(dbPath, (char *)pFile->lockingContext, len + 1); + }else{ + /* all other styles use the locking context to store the db file path */ + assert( strlen((char*)pFile->lockingContext)<=MAXPATHLEN ); + strcpy(dbPath, (char *)pFile->lockingContext); + } + return SQLITE_OK; +} + +/* +** Takes an already filled in unix file and alters it so all file locking +** will be performed on the local proxy lock file. The following fields +** are preserved in the locking context so that they can be restored and +** the unix structure properly cleaned up at close time: +** ->lockingContext +** ->pMethod +*/ +static int proxyTransformUnixFile(unixFile *pFile, const char *path) { + proxyLockingContext *pCtx; + char dbPath[MAXPATHLEN+1]; /* Name of the database file */ + char *lockPath=NULL; + int rc = SQLITE_OK; + + if( pFile->locktype!=NO_LOCK ){ + return SQLITE_BUSY; + } + proxyGetDbPathForUnixFile(pFile, dbPath); + if( !path || path[0]=='\0' || !strcmp(path, ":auto:") ){ + lockPath=NULL; + }else{ + lockPath=(char *)path; + } + + OSTRACE4("TRANSPROXY %d for %s pid=%d\n", pFile->h, + (lockPath ? lockPath : ":auto:"), getpid()); + + pCtx = sqlite3_malloc( sizeof(*pCtx) ); + if( pCtx==0 ){ + return SQLITE_NOMEM; + } + memset(pCtx, 0, sizeof(*pCtx)); + + rc = proxyCreateConchPathname(dbPath, &pCtx->conchFilePath); + if( rc==SQLITE_OK ){ + rc = proxyCreateUnixFile(pCtx->conchFilePath, &pCtx->conchFile); + } + if( rc==SQLITE_OK && lockPath ){ + pCtx->lockProxyPath = sqlite3DbStrDup(0, lockPath); + } + + if( rc==SQLITE_OK ){ + /* all memory is allocated, proxys are created and assigned, + ** switch the locking context and pMethod then return. + */ + pCtx->dbPath = sqlite3DbStrDup(0, dbPath); + pCtx->oldLockingContext = pFile->lockingContext; + pFile->lockingContext = pCtx; + pCtx->pOldMethod = pFile->pMethod; + pFile->pMethod = &proxyIoMethods; + }else{ + if( pCtx->conchFile ){ + rc = pCtx->conchFile->pMethod->xClose((sqlite3_file *)pCtx->conchFile); + if( rc ) return rc; + sqlite3_free(pCtx->conchFile); + } + sqlite3_free(pCtx->conchFilePath); + sqlite3_free(pCtx); + } + OSTRACE3("TRANSPROXY %d %s\n", pFile->h, + (rc==SQLITE_OK ? "ok" : "failed")); + return rc; +} + + +/* +** This routine handles sqlite3_file_control() calls that are specific +** to proxy locking. +*/ +static int proxyFileControl(sqlite3_file *id, int op, void *pArg){ + switch( op ){ + case SQLITE_GET_LOCKPROXYFILE: { + unixFile *pFile = (unixFile*)id; + if( pFile->pMethod == &proxyIoMethods ){ + proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext; + proxyTakeConch(pFile); + if( pCtx->lockProxyPath ){ + *(const char **)pArg = pCtx->lockProxyPath; + }else{ + *(const char **)pArg = ":auto: (not held)"; + } + } else { + *(const char **)pArg = NULL; + } + return SQLITE_OK; + } + case SQLITE_SET_LOCKPROXYFILE: { + unixFile *pFile = (unixFile*)id; + int rc = SQLITE_OK; + int isProxyStyle = (pFile->pMethod == &proxyIoMethods); + if( pArg==NULL || (const char *)pArg==0 ){ + if( isProxyStyle ){ + /* turn off proxy locking - not supported */ + rc = SQLITE_ERROR /*SQLITE_PROTOCOL? SQLITE_MISUSE?*/; + }else{ + /* turn off proxy locking - already off - NOOP */ + rc = SQLITE_OK; + } + }else{ + const char *proxyPath = (const char *)pArg; + if( isProxyStyle ){ + proxyLockingContext *pCtx = + (proxyLockingContext*)pFile->lockingContext; + if( !strcmp(pArg, ":auto:") + || (pCtx->lockProxyPath && + !strncmp(pCtx->lockProxyPath, proxyPath, MAXPATHLEN)) + ){ + rc = SQLITE_OK; + }else{ + rc = switchLockProxyPath(pFile, proxyPath); + } + }else{ + /* turn on proxy file locking */ + rc = proxyTransformUnixFile(pFile, proxyPath); + } + } + return rc; + } + default: { + assert( 0 ); /* The call assures that only valid opcodes are sent */ + } + } + /*NOTREACHED*/ + return SQLITE_ERROR; +} + +/* +** Within this division (the proxying locking implementation) the procedures +** above this point are all utilities. The lock-related methods of the +** proxy-locking sqlite3_io_method object follow. +*/ + + +/* +** 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 proxyCheckReservedLock(sqlite3_file *id, int *pResOut) { + unixFile *pFile = (unixFile*)id; + int rc = proxyTakeConch(pFile); + if( rc==SQLITE_OK ){ + proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; + unixFile *proxy = pCtx->lockProxy; + return proxy->pMethod->xCheckReservedLock((sqlite3_file*)proxy, pResOut); + } + 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 proxyLock(sqlite3_file *id, int locktype) { + unixFile *pFile = (unixFile*)id; + int rc = proxyTakeConch(pFile); + if( rc==SQLITE_OK ){ + proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; + unixFile *proxy = pCtx->lockProxy; + rc = proxy->pMethod->xLock((sqlite3_file*)proxy, locktype); + pFile->locktype = proxy->locktype; + } + 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 proxyUnlock(sqlite3_file *id, int locktype) { + unixFile *pFile = (unixFile*)id; + int rc = proxyTakeConch(pFile); + if( rc==SQLITE_OK ){ + proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; + unixFile *proxy = pCtx->lockProxy; + rc = proxy->pMethod->xUnlock((sqlite3_file*)proxy, locktype); + pFile->locktype = proxy->locktype; + } + return rc; +} + +/* +** Close a file that uses proxy locks. +*/ +static int proxyClose(sqlite3_file *id) { + if( id ){ + unixFile *pFile = (unixFile*)id; + proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; + unixFile *lockProxy = pCtx->lockProxy; + unixFile *conchFile = pCtx->conchFile; + int rc = SQLITE_OK; + + if( lockProxy ){ + rc = lockProxy->pMethod->xUnlock((sqlite3_file*)lockProxy, NO_LOCK); + if( rc ) return rc; + rc = lockProxy->pMethod->xClose((sqlite3_file*)lockProxy); + if( rc ) return rc; + sqlite3_free(lockProxy); + pCtx->lockProxy = 0; + } + if( conchFile ){ + if( pCtx->conchHeld ){ + rc = proxyReleaseConch(pFile); + if( rc ) return rc; + } + rc = conchFile->pMethod->xClose((sqlite3_file*)conchFile); + if( rc ) return rc; + sqlite3_free(conchFile); + } + sqlite3_free(pCtx->lockProxyPath); + sqlite3_free(pCtx->conchFilePath); + sqlite3_free(pCtx->dbPath); + /* restore the original locking context and pMethod then close it */ + pFile->lockingContext = pCtx->oldLockingContext; + pFile->pMethod = pCtx->pOldMethod; + sqlite3_free(pCtx); + return pFile->pMethod->xClose(id); + } + return SQLITE_OK; +} + + + +#endif /* defined(__DARWIN__) && SQLITE_ENABLE_LOCKING_STYLE */ +/* +** The proxy locking style is intended for use with AFP filesystems. +** And since AFP is only supported on MacOSX, the proxy locking is also +** restricted to MacOSX. +** +** +******************* End of the proxy lock implementation ********************** +******************************************************************************/ + /* ** Initialize the operating system interface. ** |