diff options
Diffstat (limited to 'src/os_unix.c')
| -rw-r--r-- | src/os_unix.c | 69 |
1 files changed, 28 insertions, 41 deletions
diff --git a/src/os_unix.c b/src/os_unix.c index 947f431ae..e6d1774a4 100644 --- a/src/os_unix.c +++ b/src/os_unix.c @@ -212,7 +212,6 @@ struct unixFile { UnixUnusedFd *pUnused; /* Pre-allocated UnixUnusedFd */ const char *zPath; /* Name of the file */ unixShm *pShm; /* Shared memory segment information */ - int readOnlyShm; /* True to open shared-memory read-only */ int szChunk; /* Configured by FCNTL_CHUNK_SIZE */ #if SQLITE_ENABLE_LOCKING_STYLE int openFlags; /* The flags specified at open() */ @@ -3453,10 +3452,6 @@ static int unixFileControl(sqlite3_file *id, int op, void *pArg){ case SQLITE_FCNTL_SIZE_HINT: { return fcntlSizeHint((unixFile *)id, *(i64 *)pArg); } - case SQLITE_FCNTL_READONLY_SHM: { - ((unixFile*)id)->readOnlyShm = (pArg!=0); - return SQLITE_OK; - } #ifndef NDEBUG /* The pager calls this method to signal that it has done ** a rollback and that the database is therefore unchanged and @@ -3542,11 +3537,11 @@ struct unixShmNode { char *zFilename; /* Name of the mmapped file */ int h; /* Open file descriptor */ int szRegion; /* Size of shared-memory regions */ - int nRegion; /* Size of array apRegion */ + u16 nRegion; /* Size of array apRegion */ + u8 isReadonly; /* True if read-only */ char **apRegion; /* Array of mapped shared-memory regions */ int nRef; /* Number of unixShm objects pointing to this */ unixShm *pFirst; /* All unixShm objects pointing to this */ - u8 readOnly; /* True if this is a read-only mapping */ #ifdef SQLITE_DEBUG u8 exclMask; /* Mask of exclusive locks held */ u8 sharedMask; /* Mask of shared locks held */ @@ -3787,48 +3782,38 @@ static int unixOpenSharedMemory(unixFile *pDbFd){ } if( pInode->bProcessLock==0 ){ - int flags = (pDbFd->readOnlyShm ? O_RDONLY : O_RDWR|O_CREAT); - pShmNode->h = robust_open(zShmFilename, flags, (sStat.st_mode & 0777)); + pShmNode->h = robust_open(zShmFilename, O_RDWR|O_CREAT, + (sStat.st_mode & 0777)); if( pShmNode->h<0 ){ - rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zShmFilename); - goto shm_open_err; + const char *zRO; + zRO = sqlite3_uri_parameter(pDbFd->zPath, "readonly_shm"); + if( zRO && (zRO[0]!='0' || zRO[1]!=0) ){ + pShmNode->h = robust_open(zShmFilename, O_RDONLY, + (sStat.st_mode & 0777)); + pShmNode->isReadonly = 1; + } + if( pShmNode->h<0 ){ + rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zShmFilename); + goto shm_open_err; + } } - pShmNode->readOnly = pDbFd->readOnlyShm; /* Check to see if another process is holding the dead-man switch. - ** If not, zero the first few bytes of the shared-memory file to make - ** sure it is not mistaken for valid by code in wal.c. Except, if this - ** is a read-only connection to the shared-memory then it is not possible - ** to check check if another process is holding a read-lock on the DMS - ** byte, as we cannot attempt a write-lock via a read-only file - ** descriptor. So in this case, we just assume the shared-memory - ** contents are Ok and proceed. */ - if( pShmNode->readOnly==0 ){ - rc = SQLITE_OK; - if( unixShmSystemLock(pShmNode, F_WRLCK, UNIX_SHM_DMS, 1)==SQLITE_OK ){ - if( pDbFd->readOnlyShm ){ - rc = SQLITE_IOERR_SHMOPEN; - }else if( 4!=osWrite(pShmNode->h, "\00\00\00\00", 4) ){ - rc = unixLogError(SQLITE_IOERR_SHMOPEN, "ftruncate", zShmFilename); - } - } - if( rc==SQLITE_OK ){ - rc = unixShmSystemLock(pShmNode, F_RDLCK, UNIX_SHM_DMS, 1); + ** If not, truncate the file to zero length. + */ + rc = SQLITE_OK; + if( unixShmSystemLock(pShmNode, F_WRLCK, UNIX_SHM_DMS, 1)==SQLITE_OK ){ + if( robust_ftruncate(pShmNode->h, 0) ){ + rc = unixLogError(SQLITE_IOERR_SHMOPEN, "ftruncate", zShmFilename); } - if( rc ) goto shm_open_err; } + if( rc==SQLITE_OK ){ + rc = unixShmSystemLock(pShmNode, F_RDLCK, UNIX_SHM_DMS, 1); + } + if( rc ) goto shm_open_err; } } - /* If the unixShmNode is read-only, but SQLITE_FCNTL_READONLY_SHM has not - ** been set for file-descriptor pDbFd, return an error. The wal.c module - ** will then call this function again with SQLITE_FCNTL_READONLY_SHM set. - */ - else if( pShmNode->readOnly && !pDbFd->readOnlyShm ){ - rc = SQLITE_IOERR_SHMOPEN; - goto shm_open_err; - } - /* Make the new connection a child of the unixShmNode */ p->pShmNode = pShmNode; #ifdef SQLITE_DEBUG @@ -3949,7 +3934,8 @@ static int unixShmMap( while(pShmNode->nRegion<=iRegion){ void *pMem; if( pShmNode->h>=0 ){ - pMem = mmap(0, szRegion, PROT_READ|(!pShmNode->readOnly?PROT_WRITE:0), + pMem = mmap(0, szRegion, + pShmNode->isReadonly ? PROT_READ : PROT_READ|PROT_WRITE, MAP_SHARED, pShmNode->h, pShmNode->nRegion*szRegion ); if( pMem==MAP_FAILED ){ @@ -3975,6 +3961,7 @@ shmpage_out: }else{ *pp = 0; } + if( pShmNode->isReadonly && rc==SQLITE_OK ) rc = SQLITE_READONLY; sqlite3_mutex_leave(pShmNode->mutex); return rc; } |