diff options
Diffstat (limited to 'src/os_unix.c')
| -rw-r--r-- | src/os_unix.c | 303 |
1 files changed, 189 insertions, 114 deletions
diff --git a/src/os_unix.c b/src/os_unix.c index f972b591d..458c90e8f 100644 --- a/src/os_unix.c +++ b/src/os_unix.c @@ -181,6 +181,7 @@ struct unixFile { unsigned char locktype; /* The type of lock held on this fd */ int lastErrno; /* The unix errno from the last I/O error */ void *lockingContext; /* Locking style specific state */ + int flags; /* Flags value returned by xOpen() */ #if SQLITE_ENABLE_LOCKING_STYLE int openFlags; /* The flags specified at open() */ #endif @@ -202,11 +203,6 @@ struct unixFile { unsigned char transCntrChng; /* True if the transaction counter changed */ unsigned char dbUpdate; /* True if any part of database file changed */ unsigned char inNormalWrite; /* True if in a normal write operation */ - - /* If true, that means we are dealing with a database file that has - ** a range of locking bytes from PENDING_BYTE through PENDING_BYTE+511 - ** which should never be read or written. Asserts() will verify this */ - unsigned char isLockable; /* True if file might be locked */ #endif #ifdef SQLITE_TEST /* In test mode, increase the size of this structure a bit so that @@ -753,7 +749,10 @@ struct unixOpenCnt { 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 fds awaiting close() */ + struct PendingClose { + int fd; /* File descriptor to close */ + int flags; /* Flags this file descriptor was opened with */ + } *aPending; /* Malloced space holding fds awaiting close() */ #if OS_VXWORKS sem_t *pSem; /* Named POSIX semaphore */ char aSemName[MAX_PATHNAME+1]; /* Name of that semaphore */ @@ -1406,6 +1405,60 @@ end_lock: } /* +** Close all file descriptors accumuated in the p->aPending[] array. If +** all such file descriptors are closed without error, the aPending[] +** array is deleted and SQLITE_OK returned. +** +** Otherwise, if an error occurs, then successfully closed file descriptor +** entries in the aPending[] array are set to -1, the aPending[] array +** not deleted and SQLITE_IOERR_CLOSE returned. +*/ +static int closePendingFds(unixFile *pFile){ + struct unixOpenCnt *pOpen = pFile->pOpen; + struct PendingClose *aPending = pOpen->aPending; + int i; + int rc = SQLITE_OK; + assert( unixMutexHeld() ); + for(i=0; i<pOpen->nPending; i++){ + if( aPending[i].fd>=0 ){ + if( close(aPending[i].fd) ){ + pFile->lastErrno = errno; + rc = SQLITE_IOERR_CLOSE; + }else{ + aPending[i].fd = -1; + } + } + } + if( rc==SQLITE_OK ){ + sqlite3_free(aPending); + pOpen->nPending = 0; + pOpen->aPending = 0; + } + return rc; +} + +/* +** Add the file descriptor used by file handle pFile to the corresponding +** aPending[] array to be closed after some other connection releases +** a lock. +*/ +static void setPendingFd(unixFile *pFile){ + struct PendingClose *aNew; + struct unixOpenCnt *pOpen = pFile->pOpen; + int nByte = (pOpen->nPending+1)*sizeof(pOpen->aPending[0]); + aNew = sqlite3_realloc(pOpen->aPending, nByte); + if( aNew==0 ){ + /* If a malloc fails, just leak the file descriptor */ + }else{ + pOpen->aPending = aNew; + pOpen->aPending[pOpen->nPending].fd = pFile->h; + pOpen->aPending[pOpen->nPending].flags = pFile->flags; + pOpen->nPending++; + pFile->h = -1; + } +} + +/* ** Lower the locking level on file descriptor pFile to locktype. locktype ** must be either NO_LOCK or SHARED_LOCK. ** @@ -1487,7 +1540,6 @@ static int unixUnlock(sqlite3_file *id, int locktype){ } if( locktype==NO_LOCK ){ struct unixOpenCnt *pOpen; - int rc2 = SQLITE_OK; /* Decrement the shared lock counter. Release the lock using an ** OS call only when all threads in this same process have released @@ -1522,28 +1574,11 @@ static int unixUnlock(sqlite3_file *id, int locktype){ pOpen->nLock--; assert( pOpen->nLock>=0 ); if( pOpen->nLock==0 && pOpen->nPending>0 ){ - int i; - for(i=0; i<pOpen->nPending; i++){ - /* close pending fds, but if closing fails don't free the array - ** assign -1 to the successfully closed descriptors and record the - ** error. The next attempt to unlock will try again. */ - if( pOpen->aPending[i] < 0 ) continue; - if( close(pOpen->aPending[i]) ){ - pFile->lastErrno = errno; - rc2 = SQLITE_IOERR_CLOSE; - }else{ - pOpen->aPending[i] = -1; - } - } - if( rc2==SQLITE_OK ){ - sqlite3_free(pOpen->aPending); - pOpen->nPending = 0; - pOpen->aPending = 0; + int rc2 = closePendingFds(pFile); + if( rc==SQLITE_OK ){ + rc = rc2; } } - if( rc==SQLITE_OK ){ - rc = rc2; - } } end_unlock: @@ -1612,17 +1647,7 @@ static int unixClose(sqlite3_file *id){ ** descriptor to pOpen->aPending. It will be automatically closed when ** the last lock is cleared. */ - int *aNew; - struct unixOpenCnt *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; - } + setPendingFd(pFile); } releaseLockInfo(pFile->pLock); releaseOpenCnt(pFile->pOpen); @@ -2592,26 +2617,14 @@ static int afpUnlock(sqlite3_file *id, int locktype) { pOpen->nLock--; assert( pOpen->nLock>=0 ); if( pOpen->nLock==0 && pOpen->nPending>0 ){ - int i; - for(i=0; i<pOpen->nPending; i++){ - if( pOpen->aPending[i] < 0 ) continue; - if( close(pOpen->aPending[i]) ){ - pFile->lastErrno = errno; - rc = SQLITE_IOERR_CLOSE; - }else{ - pOpen->aPending[i] = -1; - } - } - if( rc==SQLITE_OK ){ - sqlite3_free(pOpen->aPending); - pOpen->nPending = 0; - pOpen->aPending = 0; - } + rc = closePendingFds(pFile); } } } unixLeaveMutex(); - if( rc==SQLITE_OK ) pFile->locktype = locktype; + if( rc==SQLITE_OK ){ + pFile->locktype = locktype; + } return rc; } @@ -2629,17 +2642,7 @@ static int afpClose(sqlite3_file *id) { ** descriptor to pOpen->aPending. It will be automatically closed when ** the last lock is cleared. */ - int *aNew; - struct unixOpenCnt *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; - } + setPendingFd(pFile); } releaseOpenCnt(pFile->pOpen); sqlite3_free(pFile->lockingContext); @@ -2725,22 +2728,25 @@ static int unixRead( int amt, sqlite3_int64 offset ){ + unixFile *pFile = (unixFile *)id; int got; assert( id ); - /* Never read or write any of the bytes in the locking range */ - assert( ((unixFile*)id)->isLockable==0 - || offset>=PENDING_BYTE+512 - || offset+amt<=PENDING_BYTE ); + /* If this is a database file (not a journal, master-journal or temp + ** file), the bytes in the locking range should never be read or written. */ + assert( (pFile->flags&SQLITE_OPEN_MAIN_DB)==0 + || offset>=PENDING_BYTE+512 + || offset+amt<=PENDING_BYTE + ); - got = seekAndRead((unixFile*)id, offset, pBuf, amt); + got = seekAndRead(pFile, offset, pBuf, amt); if( got==amt ){ return SQLITE_OK; }else if( got<0 ){ /* lastErrno set by seekAndRead */ return SQLITE_IOERR_READ; }else{ - ((unixFile*)id)->lastErrno = 0; /* not a system error */ + pFile->lastErrno = 0; /* not a system error */ /* Unread parts of the buffer must be zero-filled */ memset(&((char*)pBuf)[got], 0, amt-got); return SQLITE_IOERR_SHORT_READ; @@ -2794,14 +2800,17 @@ static int unixWrite( int amt, sqlite3_int64 offset ){ + unixFile *pFile = (unixFile*)id; int wrote = 0; assert( id ); assert( amt>0 ); - /* Never read or write any of the bytes in the locking range */ - assert( ((unixFile*)id)->isLockable==0 - || offset>=PENDING_BYTE+512 - || offset+amt<=PENDING_BYTE ); + /* If this is a database file (not a journal, master-journal or temp + ** file), the bytes in the locking range should never be read or written. */ + assert( (pFile->flags&SQLITE_OPEN_MAIN_DB)==0 + || offset>=PENDING_BYTE+512 + || offset+amt<=PENDING_BYTE + ); #ifndef NDEBUG /* If we are doing a normal write to a database file (as opposed to @@ -2810,8 +2819,7 @@ static int unixWrite( ** has changed. If the transaction counter is modified, record that ** fact too. */ - if( ((unixFile*)id)->inNormalWrite ){ - unixFile *pFile = (unixFile*)id; + if( pFile->inNormalWrite ){ pFile->dbUpdate = 1; /* The database has been modified */ if( offset<=24 && offset+amt>=27 ){ int rc; @@ -2826,7 +2834,7 @@ static int unixWrite( } #endif - while( amt>0 && (wrote = seekAndWrite((unixFile*)id, offset, pBuf, amt))>0 ){ + while( amt>0 && (wrote = seekAndWrite(pFile, offset, pBuf, amt))>0 ){ amt -= wrote; offset += wrote; pBuf = &((char*)pBuf)[wrote]; @@ -2838,7 +2846,7 @@ static int unixWrite( /* lastErrno set by seekAndWrite */ return SQLITE_IOERR_WRITE; }else{ - ((unixFile*)id)->lastErrno = 0; /* not a system error */ + pFile->lastErrno = 0; /* not a system error */ return SQLITE_FULL; } } @@ -3650,6 +3658,58 @@ static int getTempname(int nBuf, char *zBuf){ static int proxyTransformUnixFile(unixFile*, const char*); #endif +/* +** Search for an unused file descriptor that was opened on the database +** file (not a journal or master-journal file) identified by pathname +** zPath with SQLITE_OPEN_XXX flags matching those passed as the second +** argument to this function. +** +** Such a file descriptor may exist if a database connection was closed +** but the associated file descriptor could not be closed because some +** other file descriptor open on the same file is holding a file-lock. +** Refer to comments in the unixClose() function and the lengthy comment +** describing "Posix Advisory Locking" at the start of this file for +** further details. Also, ticket #4018. +** +** If a suitable file descriptor is found, then it is returned. If no +** such file descriptor is located, -1 is returned. +*/ +static int findReusableFd(const char *zPath, int flags){ + int fd = -1; /* Return value */ + struct stat sStat; /* Results of stat() call */ + + /* A stat() call may fail for various reasons. If this happens, it is + ** almost certain that an open() call on the same path will also fail. + ** For this reason, if an error occurs in the stat() call here, it is + ** ignored and -1 is returned. The caller will try to open a new file + ** descriptor on the same path, fail, and return an error to SQLite. + ** + ** Even if a subsequent open() call does succeed, the consequences of + ** not searching for a resusable file descriptor are not dire. */ + if( 0==stat(zPath, &sStat) ){ + struct unixOpenCnt *p; + struct unixFileId id; + id.dev = sStat.st_dev; + id.ino = sStat.st_ino; + + unixEnterMutex(); + for(p=openList; p&& memcmp(&id, &p->fileId, sizeof(id)); p=p->pNext); + if( p && p->aPending ){ + int i; + struct PendingClose *aPending = p->aPending; + for(i=0; i<p->nPending; i++){ + if( aPending[i].fd>=0 && flags==aPending[i].flags ){ + fd = aPending[i].fd; + aPending[i].fd = -1; + break; + } + } + } + unixLeaveMutex(); + } + + return fd; +} /* ** Open the file zPath. @@ -3680,12 +3740,13 @@ static int unixOpen( int flags, /* Input flags to control the opening */ int *pOutFlags /* Output flags returned to SQLite core */ ){ - int fd = -1; /* File descriptor returned by open() */ + unixFile *p = (unixFile *)pFile; + int fd = -1; /* File descriptor returned by open() */ int dirfd = -1; /* Directory file descriptor */ int openFlags = 0; /* Flags to pass to open() */ int eType = flags&0xFFFFFF00; /* Type of file to open */ int noLock; /* True to omit locking primitives */ - int rc = SQLITE_OK; + int rc = SQLITE_OK; /* Function Return Code */ int isExclusive = (flags & SQLITE_OPEN_EXCLUSIVE); int isDelete = (flags & SQLITE_OPEN_DELETEONCLOSE); @@ -3720,11 +3781,10 @@ static int unixOpen( 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 ); + ** deleted. Nor are they ever temporary files. */ + assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_DB ); + assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_JOURNAL ); + assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MASTER_JOURNAL ); /* Assert that the upper layer has set one of the "file-type" flags. */ assert( eType==SQLITE_OPEN_MAIN_DB || eType==SQLITE_OPEN_TEMP_DB @@ -3733,9 +3793,19 @@ static int unixOpen( || eType==SQLITE_OPEN_TRANSIENT_DB ); - memset(pFile, 0, sizeof(unixFile)); + memset(p, 0, sizeof(unixFile)); - if( !zName ){ + if( eType==SQLITE_OPEN_MAIN_DB ){ + /* Try to find an unused file descriptor to reuse. This is not done + ** for vxworks. Not because vxworks would not benefit from the change + ** (it might, we're not sure), but because no way to test it is + ** currently available. It is better not to risk breaking vxworks for + ** the sake of such an obscure feature. */ +#if !OS_VXWORKS + fd = findReusableFd(zName, flags); +#endif + }else if( !zName ){ + /* If zName is NULL, the upper layer is requesting a temp file. */ assert(isDelete && !isOpenDirectory); rc = getTempname(MAX_PATHNAME+1, zTmpname); if( rc!=SQLITE_OK ){ @@ -3744,23 +3814,35 @@ static int unixOpen( zName = zTmpname; } + /* Determine the value of the flags parameter passed to POSIX function + ** open(). These must be calculated even if open() is not called, as + ** they may be stored as part of the file handle and used by the + ** 'conch file' locking functions later on. */ if( isReadonly ) openFlags |= O_RDONLY; if( isReadWrite ) openFlags |= O_RDWR; if( isCreate ) openFlags |= O_CREAT; if( isExclusive ) openFlags |= (O_EXCL|O_NOFOLLOW); openFlags |= (O_LARGEFILE|O_BINARY); - fd = open(zName, openFlags, isDelete?0600:SQLITE_DEFAULT_FILE_PERMISSIONS); - OSTRACE4("OPENX %-3d %s 0%o\n", fd, zName, openFlags); - 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; + fd = open(zName, openFlags, isDelete?0600:SQLITE_DEFAULT_FILE_PERMISSIONS); + OSTRACE4("OPENX %-3d %s 0%o\n", fd, zName, openFlags); + 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; + } } + assert( fd>=0 ); + p->flags = flags; + if( pOutFlags ){ + *pOutFlags = flags; + } + if( isDelete ){ #if OS_VXWORKS zPath = zName; @@ -3770,24 +3852,19 @@ static int unixOpen( } #if SQLITE_ENABLE_LOCKING_STYLE else{ - ((unixFile*)pFile)->openFlags = openFlags; - } -#endif - if( pOutFlags ){ - *pOutFlags = flags; - } - -#ifndef NDEBUG - if( (flags & SQLITE_OPEN_MAIN_DB)!=0 ){ - ((unixFile*)pFile)->isLockable = 1; + p->openFlags = openFlags; } #endif - assert( fd>=0 ); if( isOpenDirectory ){ rc = openDirectory(zPath, &dirfd); if( rc!=SQLITE_OK ){ - close(fd); /* silently leak if fail, already in error */ + /* It is safe to close fd at this point, because it is guaranteed not + ** to be open on a database file. If it were open on a database file, + ** it would not be safe to close as this would cause any locks held + ** on the file by this process to be released. */ + assert( eType!=SQLITE_OPEN_MAIN_DB ); + close(fd); /* silently leak if fail, already in error */ return rc; } } @@ -3803,16 +3880,14 @@ static int unixOpen( char *envforce = getenv("SQLITE_FORCE_PROXY_LOCKING"); int useProxy = 0; - /* SQLITE_FORCE_PROXY_LOCKING==1 means force always use proxy, - ** 0 means never use proxy, NULL means use proxy for non-local files only - */ + /* SQLITE_FORCE_PROXY_LOCKING==1 means force always use proxy, 0 means + ** never use proxy, NULL means use proxy for non-local files only. */ if( envforce!=NULL ){ useProxy = atoi(envforce)>0; }else{ struct statfs fsInfo; - if( statfs(zPath, &fsInfo) == -1 ){ - ((unixFile*)pFile)->lastErrno = errno; + ((unixFile*)pFile)->lastErrno = errno; if( dirfd>=0 ) close(dirfd); /* silently leak if fail, in error */ close(fd); /* silently leak if fail, in error */ return SQLITE_IOERR_ACCESS; |