| /* |
| ** 2007 May 1 |
| ** |
| ** 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 used to implement incremental BLOB I/O. |
| */ |
| |
| #include "sqliteInt.h" |
| #include "vdbeInt.h" |
| |
| #ifndef SQLITE_OMIT_INCRBLOB |
| |
| /* |
| ** Valid sqlite3_blob* handles point to Incrblob structures. |
| */ |
| typedef struct Incrblob Incrblob; |
| struct Incrblob { |
| int flags; /* Copy of "flags" passed to sqlite3_blob_open() */ |
| int nByte; /* Size of open blob, in bytes */ |
| int iOffset; /* Byte offset of blob in cursor data */ |
| int iCol; /* Table column this handle is open on */ |
| BtCursor *pCsr; /* Cursor pointing at blob row */ |
| sqlite3_stmt *pStmt; /* Statement holding cursor open */ |
| sqlite3 *db; /* The associated database */ |
| }; |
| |
| |
| /* |
| ** This function is used by both blob_open() and blob_reopen(). It seeks |
| ** the b-tree cursor associated with blob handle p to point to row iRow. |
| ** If successful, SQLITE_OK is returned and subsequent calls to |
| ** sqlite3_blob_read() or sqlite3_blob_write() access the specified row. |
| ** |
| ** If an error occurs, or if the specified row does not exist or does not |
| ** contain a value of type TEXT or BLOB in the column nominated when the |
| ** blob handle was opened, then an error code is returned and *pzErr may |
| ** be set to point to a buffer containing an error message. It is the |
| ** responsibility of the caller to free the error message buffer using |
| ** sqlite3DbFree(). |
| ** |
| ** If an error does occur, then the b-tree cursor is closed. All subsequent |
| ** calls to sqlite3_blob_read(), blob_write() or blob_reopen() will |
| ** immediately return SQLITE_ABORT. |
| */ |
| static int blobSeekToRow(Incrblob *p, sqlite3_int64 iRow, char **pzErr){ |
| int rc; /* Error code */ |
| char *zErr = 0; /* Error message */ |
| Vdbe *v = (Vdbe *)p->pStmt; |
| |
| /* Set the value of the SQL statements only variable to integer iRow. |
| ** This is done directly instead of using sqlite3_bind_int64() to avoid |
| ** triggering asserts related to mutexes. |
| */ |
| assert( v->aVar[0].flags&MEM_Int ); |
| v->aVar[0].u.i = iRow; |
| |
| rc = sqlite3_step(p->pStmt); |
| if( rc==SQLITE_ROW ){ |
| u32 type = v->apCsr[0]->aType[p->iCol]; |
| if( type<12 ){ |
| zErr = sqlite3MPrintf(p->db, "cannot open value of type %s", |
| type==0?"null": type==7?"real": "integer" |
| ); |
| rc = SQLITE_ERROR; |
| sqlite3_finalize(p->pStmt); |
| p->pStmt = 0; |
| }else{ |
| p->iOffset = v->apCsr[0]->aOffset[p->iCol]; |
| p->nByte = sqlite3VdbeSerialTypeLen(type); |
| p->pCsr = v->apCsr[0]->pCursor; |
| sqlite3BtreeEnterCursor(p->pCsr); |
| sqlite3BtreeCacheOverflow(p->pCsr); |
| sqlite3BtreeLeaveCursor(p->pCsr); |
| } |
| } |
| |
| if( rc==SQLITE_ROW ){ |
| rc = SQLITE_OK; |
| }else if( p->pStmt ){ |
| rc = sqlite3_finalize(p->pStmt); |
| p->pStmt = 0; |
| if( rc==SQLITE_OK ){ |
| zErr = sqlite3MPrintf(p->db, "no such rowid: %lld", iRow); |
| rc = SQLITE_ERROR; |
| }else{ |
| zErr = sqlite3MPrintf(p->db, "%s", sqlite3_errmsg(p->db)); |
| } |
| } |
| |
| assert( rc!=SQLITE_OK || zErr==0 ); |
| assert( rc!=SQLITE_ROW && rc!=SQLITE_DONE ); |
| |
| *pzErr = zErr; |
| return rc; |
| } |
| |
| /* |
| ** Open a blob handle. |
| */ |
| int sqlite3_blob_open( |
| sqlite3* db, /* The database connection */ |
| const char *zDb, /* The attached database containing the blob */ |
| const char *zTable, /* The table containing the blob */ |
| const char *zColumn, /* The column containing the blob */ |
| sqlite_int64 iRow, /* The row containing the glob */ |
| int flags, /* True -> read/write access, false -> read-only */ |
| sqlite3_blob **ppBlob /* Handle for accessing the blob returned here */ |
| ){ |
| int nAttempt = 0; |
| int iCol; /* Index of zColumn in row-record */ |
| |
| /* This VDBE program seeks a btree cursor to the identified |
| ** db/table/row entry. The reason for using a vdbe program instead |
| ** of writing code to use the b-tree layer directly is that the |
| ** vdbe program will take advantage of the various transaction, |
| ** locking and error handling infrastructure built into the vdbe. |
| ** |
| ** After seeking the cursor, the vdbe executes an OP_ResultRow. |
| ** Code external to the Vdbe then "borrows" the b-tree cursor and |
| ** uses it to implement the blob_read(), blob_write() and |
| ** blob_bytes() functions. |
| ** |
| ** The sqlite3_blob_close() function finalizes the vdbe program, |
| ** which closes the b-tree cursor and (possibly) commits the |
| ** transaction. |
| */ |
| static const VdbeOpList openBlob[] = { |
| {OP_Transaction, 0, 0, 0}, /* 0: Start a transaction */ |
| {OP_VerifyCookie, 0, 0, 0}, /* 1: Check the schema cookie */ |
| {OP_TableLock, 0, 0, 0}, /* 2: Acquire a read or write lock */ |
| |
| /* One of the following two instructions is replaced by an OP_Noop. */ |
| {OP_OpenRead, 0, 0, 0}, /* 3: Open cursor 0 for reading */ |
| {OP_OpenWrite, 0, 0, 0}, /* 4: Open cursor 0 for read/write */ |
| |
| {OP_Variable, 1, 1, 1}, /* 5: Push the rowid to the stack */ |
| {OP_NotExists, 0, 10, 1}, /* 6: Seek the cursor */ |
| {OP_Column, 0, 0, 1}, /* 7 */ |
| {OP_ResultRow, 1, 0, 0}, /* 8 */ |
| {OP_Goto, 0, 5, 0}, /* 9 */ |
| {OP_Close, 0, 0, 0}, /* 10 */ |
| {OP_Halt, 0, 0, 0}, /* 11 */ |
| }; |
| |
| int rc = SQLITE_OK; |
| char *zErr = 0; |
| Table *pTab; |
| Parse *pParse = 0; |
| Incrblob *pBlob = 0; |
| |
| flags = !!flags; /* flags = (flags ? 1 : 0); */ |
| *ppBlob = 0; |
| |
| sqlite3_mutex_enter(db->mutex); |
| |
| pBlob = (Incrblob *)sqlite3DbMallocZero(db, sizeof(Incrblob)); |
| if( !pBlob ) goto blob_open_out; |
| pParse = sqlite3StackAllocRaw(db, sizeof(*pParse)); |
| if( !pParse ) goto blob_open_out; |
| |
| do { |
| memset(pParse, 0, sizeof(Parse)); |
| pParse->db = db; |
| sqlite3DbFree(db, zErr); |
| zErr = 0; |
| |
| sqlite3BtreeEnterAll(db); |
| pTab = sqlite3LocateTable(pParse, 0, zTable, zDb); |
| if( pTab && IsVirtual(pTab) ){ |
| pTab = 0; |
| sqlite3ErrorMsg(pParse, "cannot open virtual table: %s", zTable); |
| } |
| #ifndef SQLITE_OMIT_VIEW |
| if( pTab && pTab->pSelect ){ |
| pTab = 0; |
| sqlite3ErrorMsg(pParse, "cannot open view: %s", zTable); |
| } |
| #endif |
| if( !pTab ){ |
| if( pParse->zErrMsg ){ |
| sqlite3DbFree(db, zErr); |
| zErr = pParse->zErrMsg; |
| pParse->zErrMsg = 0; |
| } |
| rc = SQLITE_ERROR; |
| sqlite3BtreeLeaveAll(db); |
| goto blob_open_out; |
| } |
| |
| /* Now search pTab for the exact column. */ |
| for(iCol=0; iCol<pTab->nCol; iCol++) { |
| if( sqlite3StrICmp(pTab->aCol[iCol].zName, zColumn)==0 ){ |
| break; |
| } |
| } |
| if( iCol==pTab->nCol ){ |
| sqlite3DbFree(db, zErr); |
| zErr = sqlite3MPrintf(db, "no such column: \"%s\"", zColumn); |
| rc = SQLITE_ERROR; |
| sqlite3BtreeLeaveAll(db); |
| goto blob_open_out; |
| } |
| |
| /* If the value is being opened for writing, check that the |
| ** column is not indexed, and that it is not part of a foreign key. |
| ** It is against the rules to open a column to which either of these |
| ** descriptions applies for writing. */ |
| if( flags ){ |
| const char *zFault = 0; |
| Index *pIdx; |
| #ifndef SQLITE_OMIT_FOREIGN_KEY |
| if( db->flags&SQLITE_ForeignKeys ){ |
| /* Check that the column is not part of an FK child key definition. It |
| ** is not necessary to check if it is part of a parent key, as parent |
| ** key columns must be indexed. The check below will pick up this |
| ** case. */ |
| FKey *pFKey; |
| for(pFKey=pTab->pFKey; pFKey; pFKey=pFKey->pNextFrom){ |
| int j; |
| for(j=0; j<pFKey->nCol; j++){ |
| if( pFKey->aCol[j].iFrom==iCol ){ |
| zFault = "foreign key"; |
| } |
| } |
| } |
| } |
| #endif |
| for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ |
| int j; |
| for(j=0; j<pIdx->nColumn; j++){ |
| if( pIdx->aiColumn[j]==iCol ){ |
| zFault = "indexed"; |
| } |
| } |
| } |
| if( zFault ){ |
| sqlite3DbFree(db, zErr); |
| zErr = sqlite3MPrintf(db, "cannot open %s column for writing", zFault); |
| rc = SQLITE_ERROR; |
| sqlite3BtreeLeaveAll(db); |
| goto blob_open_out; |
| } |
| } |
| |
| pBlob->pStmt = (sqlite3_stmt *)sqlite3VdbeCreate(db); |
| assert( pBlob->pStmt || db->mallocFailed ); |
| if( pBlob->pStmt ){ |
| Vdbe *v = (Vdbe *)pBlob->pStmt; |
| int iDb = sqlite3SchemaToIndex(db, pTab->pSchema); |
| |
| sqlite3VdbeAddOpList(v, sizeof(openBlob)/sizeof(VdbeOpList), openBlob); |
| |
| |
| /* Configure the OP_Transaction */ |
| sqlite3VdbeChangeP1(v, 0, iDb); |
| sqlite3VdbeChangeP2(v, 0, flags); |
| |
| /* Configure the OP_VerifyCookie */ |
| sqlite3VdbeChangeP1(v, 1, iDb); |
| sqlite3VdbeChangeP2(v, 1, pTab->pSchema->schema_cookie); |
| sqlite3VdbeChangeP3(v, 1, pTab->pSchema->iGeneration); |
| |
| /* Make sure a mutex is held on the table to be accessed */ |
| sqlite3VdbeUsesBtree(v, iDb); |
| |
| /* Configure the OP_TableLock instruction */ |
| #ifdef SQLITE_OMIT_SHARED_CACHE |
| sqlite3VdbeChangeToNoop(v, 2, 1); |
| #else |
| sqlite3VdbeChangeP1(v, 2, iDb); |
| sqlite3VdbeChangeP2(v, 2, pTab->tnum); |
| sqlite3VdbeChangeP3(v, 2, flags); |
| sqlite3VdbeChangeP4(v, 2, pTab->zName, P4_TRANSIENT); |
| #endif |
| |
| /* Remove either the OP_OpenWrite or OpenRead. Set the P2 |
| ** parameter of the other to pTab->tnum. */ |
| sqlite3VdbeChangeToNoop(v, 4 - flags, 1); |
| sqlite3VdbeChangeP2(v, 3 + flags, pTab->tnum); |
| sqlite3VdbeChangeP3(v, 3 + flags, iDb); |
| |
| /* Configure the number of columns. Configure the cursor to |
| ** think that the table has one more column than it really |
| ** does. An OP_Column to retrieve this imaginary column will |
| ** always return an SQL NULL. This is useful because it means |
| ** we can invoke OP_Column to fill in the vdbe cursors type |
| ** and offset cache without causing any IO. |
| */ |
| sqlite3VdbeChangeP4(v, 3+flags, SQLITE_INT_TO_PTR(pTab->nCol+1),P4_INT32); |
| sqlite3VdbeChangeP2(v, 7, pTab->nCol); |
| if( !db->mallocFailed ){ |
| sqlite3VdbeMakeReady(v, 1, 1, 1, 0, 0, 0); |
| } |
| } |
| |
| pBlob->flags = flags; |
| pBlob->iCol = iCol; |
| pBlob->db = db; |
| sqlite3BtreeLeaveAll(db); |
| if( db->mallocFailed ){ |
| goto blob_open_out; |
| } |
| sqlite3_bind_int64(pBlob->pStmt, 1, iRow); |
| rc = blobSeekToRow(pBlob, iRow, &zErr); |
| } while( (++nAttempt)<5 && rc==SQLITE_SCHEMA ); |
| |
| blob_open_out: |
| if( rc==SQLITE_OK && db->mallocFailed==0 ){ |
| *ppBlob = (sqlite3_blob *)pBlob; |
| }else{ |
| if( pBlob && pBlob->pStmt ) sqlite3VdbeFinalize((Vdbe *)pBlob->pStmt); |
| sqlite3DbFree(db, pBlob); |
| } |
| sqlite3Error(db, rc, (zErr ? "%s" : 0), zErr); |
| sqlite3DbFree(db, zErr); |
| sqlite3StackFree(db, pParse); |
| rc = sqlite3ApiExit(db, rc); |
| sqlite3_mutex_leave(db->mutex); |
| return rc; |
| } |
| |
| /* |
| ** Close a blob handle that was previously created using |
| ** sqlite3_blob_open(). |
| */ |
| int sqlite3_blob_close(sqlite3_blob *pBlob){ |
| Incrblob *p = (Incrblob *)pBlob; |
| int rc; |
| sqlite3 *db; |
| |
| if( p ){ |
| db = p->db; |
| sqlite3_mutex_enter(db->mutex); |
| rc = sqlite3_finalize(p->pStmt); |
| sqlite3DbFree(db, p); |
| sqlite3_mutex_leave(db->mutex); |
| }else{ |
| rc = SQLITE_OK; |
| } |
| return rc; |
| } |
| |
| /* |
| ** Perform a read or write operation on a blob |
| */ |
| static int blobReadWrite( |
| sqlite3_blob *pBlob, |
| void *z, |
| int n, |
| int iOffset, |
| int (*xCall)(BtCursor*, u32, u32, void*) |
| ){ |
| int rc; |
| Incrblob *p = (Incrblob *)pBlob; |
| Vdbe *v; |
| sqlite3 *db; |
| |
| if( p==0 ) return SQLITE_MISUSE_BKPT; |
| db = p->db; |
| sqlite3_mutex_enter(db->mutex); |
| v = (Vdbe*)p->pStmt; |
| |
| if( n<0 || iOffset<0 || (iOffset+n)>p->nByte ){ |
| /* Request is out of range. Return a transient error. */ |
| rc = SQLITE_ERROR; |
| sqlite3Error(db, SQLITE_ERROR, 0); |
| }else if( v==0 ){ |
| /* If there is no statement handle, then the blob-handle has |
| ** already been invalidated. Return SQLITE_ABORT in this case. |
| */ |
| rc = SQLITE_ABORT; |
| }else{ |
| /* Call either BtreeData() or BtreePutData(). If SQLITE_ABORT is |
| ** returned, clean-up the statement handle. |
| */ |
| assert( db == v->db ); |
| sqlite3BtreeEnterCursor(p->pCsr); |
| rc = xCall(p->pCsr, iOffset+p->iOffset, n, z); |
| sqlite3BtreeLeaveCursor(p->pCsr); |
| if( rc==SQLITE_ABORT ){ |
| sqlite3VdbeFinalize(v); |
| p->pStmt = 0; |
| }else{ |
| db->errCode = rc; |
| v->rc = rc; |
| } |
| } |
| rc = sqlite3ApiExit(db, rc); |
| sqlite3_mutex_leave(db->mutex); |
| return rc; |
| } |
| |
| /* |
| ** Read data from a blob handle. |
| */ |
| int sqlite3_blob_read(sqlite3_blob *pBlob, void *z, int n, int iOffset){ |
| return blobReadWrite(pBlob, z, n, iOffset, sqlite3BtreeData); |
| } |
| |
| /* |
| ** Write data to a blob handle. |
| */ |
| int sqlite3_blob_write(sqlite3_blob *pBlob, const void *z, int n, int iOffset){ |
| return blobReadWrite(pBlob, (void *)z, n, iOffset, sqlite3BtreePutData); |
| } |
| |
| /* |
| ** Query a blob handle for the size of the data. |
| ** |
| ** The Incrblob.nByte field is fixed for the lifetime of the Incrblob |
| ** so no mutex is required for access. |
| */ |
| int sqlite3_blob_bytes(sqlite3_blob *pBlob){ |
| Incrblob *p = (Incrblob *)pBlob; |
| return (p && p->pStmt) ? p->nByte : 0; |
| } |
| |
| /* |
| ** Move an existing blob handle to point to a different row of the same |
| ** database table. |
| ** |
| ** If an error occurs, or if the specified row does not exist or does not |
| ** contain a blob or text value, then an error code is returned and the |
| ** database handle error code and message set. If this happens, then all |
| ** subsequent calls to sqlite3_blob_xxx() functions (except blob_close()) |
| ** immediately return SQLITE_ABORT. |
| */ |
| int sqlite3_blob_reopen(sqlite3_blob *pBlob, sqlite3_int64 iRow){ |
| int rc; |
| Incrblob *p = (Incrblob *)pBlob; |
| sqlite3 *db; |
| |
| if( p==0 ) return SQLITE_MISUSE_BKPT; |
| db = p->db; |
| sqlite3_mutex_enter(db->mutex); |
| |
| if( p->pStmt==0 ){ |
| /* If there is no statement handle, then the blob-handle has |
| ** already been invalidated. Return SQLITE_ABORT in this case. |
| */ |
| rc = SQLITE_ABORT; |
| }else{ |
| char *zErr; |
| rc = blobSeekToRow(p, iRow, &zErr); |
| if( rc!=SQLITE_OK ){ |
| sqlite3Error(db, rc, (zErr ? "%s" : 0), zErr); |
| sqlite3DbFree(db, zErr); |
| } |
| assert( rc!=SQLITE_SCHEMA ); |
| } |
| |
| rc = sqlite3ApiExit(db, rc); |
| assert( rc==SQLITE_OK || p->pStmt==0 ); |
| sqlite3_mutex_leave(db->mutex); |
| return rc; |
| } |
| |
| #endif /* #ifndef SQLITE_OMIT_INCRBLOB */ |