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Diffstat (limited to 'src/vdbeblob.c')
| -rw-r--r-- | src/vdbeblob.c | 515 |
1 files changed, 515 insertions, 0 deletions
diff --git a/src/vdbeblob.c b/src/vdbeblob.c new file mode 100644 index 0000000..522447d --- /dev/null +++ b/src/vdbeblob.c @@ -0,0 +1,515 @@ +/* +** 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 nByte; /* Size of open blob, in bytes */ + int iOffset; /* Byte offset of blob in cursor data */ + u16 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 */ + char *zDb; /* Database name */ + Table *pTab; /* Table object */ +}; + + +/* +** 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 register r[1] in the SQL statement to integer iRow. + ** This is done directly as a performance optimization + */ + sqlite3VdbeMemSetInt64(&v->aMem[1], iRow); + + /* If the statement has been run before (and is paused at the OP_ResultRow) + ** then back it up to the point where it does the OP_NotExists. This could + ** have been down with an extra OP_Goto, but simply setting the program + ** counter is faster. */ + if( v->pc>4 ){ + v->pc = 4; + assert( v->aOp[v->pc].opcode==OP_NotExists ); + rc = sqlite3VdbeExec(v); + }else{ + rc = sqlite3_step(p->pStmt); + } + if( rc==SQLITE_ROW ){ + VdbeCursor *pC = v->apCsr[0]; + u32 type; + assert( pC!=0 ); + assert( pC->eCurType==CURTYPE_BTREE ); + type = pC->nHdrParsed>p->iCol ? pC->aType[p->iCol] : 0; + testcase( pC->nHdrParsed==p->iCol ); + testcase( pC->nHdrParsed==p->iCol+1 ); + 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 = pC->aType[p->iCol + pC->nField]; + p->nByte = sqlite3VdbeSerialTypeLen(type); + p->pCsr = pC->uc.pCursor; + sqlite3BtreeIncrblobCursor(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 wrFlag, /* 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 */ + int rc = SQLITE_OK; + char *zErr = 0; + Table *pTab; + Incrblob *pBlob = 0; + Parse sParse; + +#ifdef SQLITE_ENABLE_API_ARMOR + if( ppBlob==0 ){ + return SQLITE_MISUSE_BKPT; + } +#endif + *ppBlob = 0; +#ifdef SQLITE_ENABLE_API_ARMOR + if( !sqlite3SafetyCheckOk(db) || zTable==0 || zColumn==0 ){ + return SQLITE_MISUSE_BKPT; + } +#endif + wrFlag = !!wrFlag; /* wrFlag = (wrFlag ? 1 : 0); */ + + sqlite3_mutex_enter(db->mutex); + + pBlob = (Incrblob *)sqlite3DbMallocZero(db, sizeof(Incrblob)); + while(1){ + sqlite3ParseObjectInit(&sParse,db); + if( !pBlob ) goto blob_open_out; + sqlite3DbFree(db, zErr); + zErr = 0; + + sqlite3BtreeEnterAll(db); + pTab = sqlite3LocateTable(&sParse, 0, zTable, zDb); + if( pTab && IsVirtual(pTab) ){ + pTab = 0; + sqlite3ErrorMsg(&sParse, "cannot open virtual table: %s", zTable); + } + if( pTab && !HasRowid(pTab) ){ + pTab = 0; + sqlite3ErrorMsg(&sParse, "cannot open table without rowid: %s", zTable); + } +#ifndef SQLITE_OMIT_VIEW + if( pTab && IsView(pTab) ){ + pTab = 0; + sqlite3ErrorMsg(&sParse, "cannot open view: %s", zTable); + } +#endif + if( !pTab ){ + if( sParse.zErrMsg ){ + sqlite3DbFree(db, zErr); + zErr = sParse.zErrMsg; + sParse.zErrMsg = 0; + } + rc = SQLITE_ERROR; + sqlite3BtreeLeaveAll(db); + goto blob_open_out; + } + pBlob->pTab = pTab; + pBlob->zDb = db->aDb[sqlite3SchemaToIndex(db, pTab->pSchema)].zDbSName; + + /* Now search pTab for the exact column. */ + for(iCol=0; iCol<pTab->nCol; iCol++) { + if( sqlite3StrICmp(pTab->aCol[iCol].zCnName, 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. + */ + if( wrFlag ){ + 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; + assert( IsOrdinaryTable(pTab) ); + for(pFKey=pTab->u.tab.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->nKeyCol; j++){ + /* FIXME: Be smarter about indexes that use expressions */ + if( pIdx->aiColumn[j]==iCol || pIdx->aiColumn[j]==XN_EXPR ){ + 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(&sParse); + assert( pBlob->pStmt || db->mallocFailed ); + if( pBlob->pStmt ){ + + /* 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 int iLn = VDBE_OFFSET_LINENO(2); + static const VdbeOpList openBlob[] = { + {OP_TableLock, 0, 0, 0}, /* 0: Acquire a read or write lock */ + {OP_OpenRead, 0, 0, 0}, /* 1: Open a cursor */ + /* blobSeekToRow() will initialize r[1] to the desired rowid */ + {OP_NotExists, 0, 5, 1}, /* 2: Seek the cursor to rowid=r[1] */ + {OP_Column, 0, 0, 1}, /* 3 */ + {OP_ResultRow, 1, 0, 0}, /* 4 */ + {OP_Halt, 0, 0, 0}, /* 5 */ + }; + Vdbe *v = (Vdbe *)pBlob->pStmt; + int iDb = sqlite3SchemaToIndex(db, pTab->pSchema); + VdbeOp *aOp; + + sqlite3VdbeAddOp4Int(v, OP_Transaction, iDb, wrFlag, + pTab->pSchema->schema_cookie, + pTab->pSchema->iGeneration); + sqlite3VdbeChangeP5(v, 1); + assert( sqlite3VdbeCurrentAddr(v)==2 || db->mallocFailed ); + aOp = sqlite3VdbeAddOpList(v, ArraySize(openBlob), openBlob, iLn); + + /* Make sure a mutex is held on the table to be accessed */ + sqlite3VdbeUsesBtree(v, iDb); + + if( db->mallocFailed==0 ){ + assert( aOp!=0 ); + /* Configure the OP_TableLock instruction */ +#ifdef SQLITE_OMIT_SHARED_CACHE + aOp[0].opcode = OP_Noop; +#else + aOp[0].p1 = iDb; + aOp[0].p2 = pTab->tnum; + aOp[0].p3 = wrFlag; + sqlite3VdbeChangeP4(v, 2, pTab->zName, P4_TRANSIENT); + } + if( db->mallocFailed==0 ){ +#endif + + /* Remove either the OP_OpenWrite or OpenRead. Set the P2 + ** parameter of the other to pTab->tnum. */ + if( wrFlag ) aOp[1].opcode = OP_OpenWrite; + aOp[1].p2 = pTab->tnum; + aOp[1].p3 = 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. + */ + aOp[1].p4type = P4_INT32; + aOp[1].p4.i = pTab->nCol+1; + aOp[3].p2 = pTab->nCol; + + sParse.nVar = 0; + sParse.nMem = 1; + sParse.nTab = 1; + sqlite3VdbeMakeReady(v, &sParse); + } + } + + pBlob->iCol = iCol; + pBlob->db = db; + sqlite3BtreeLeaveAll(db); + if( db->mallocFailed ){ + goto blob_open_out; + } + rc = blobSeekToRow(pBlob, iRow, &zErr); + if( (++nAttempt)>=SQLITE_MAX_SCHEMA_RETRY || rc!=SQLITE_SCHEMA ) break; + sqlite3ParseObjectReset(&sParse); + } + +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); + } + sqlite3ErrorWithMsg(db, rc, (zErr ? "%s" : (char*)0), zErr); + sqlite3DbFree(db, zErr); + sqlite3ParseObjectReset(&sParse); + 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 ){ + sqlite3_stmt *pStmt = p->pStmt; + db = p->db; + sqlite3_mutex_enter(db->mutex); + sqlite3DbFree(db, p); + sqlite3_mutex_leave(db->mutex); + rc = sqlite3_finalize(pStmt); + }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 || ((sqlite3_int64)iOffset+n)>p->nByte ){ + /* Request is out of range. Return a transient error. */ + rc = SQLITE_ERROR; + }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); + +#ifdef SQLITE_ENABLE_PREUPDATE_HOOK + if( xCall==sqlite3BtreePutData && db->xPreUpdateCallback ){ + /* If a pre-update hook is registered and this is a write cursor, + ** invoke it here. + ** + ** TODO: The preupdate-hook is passed SQLITE_DELETE, even though this + ** operation should really be an SQLITE_UPDATE. This is probably + ** incorrect, but is convenient because at this point the new.* values + ** are not easily obtainable. And for the sessions module, an + ** SQLITE_UPDATE where the PK columns do not change is handled in the + ** same way as an SQLITE_DELETE (the SQLITE_DELETE code is actually + ** slightly more efficient). Since you cannot write to a PK column + ** using the incremental-blob API, this works. For the sessions module + ** anyhow. + */ + sqlite3_int64 iKey; + iKey = sqlite3BtreeIntegerKey(p->pCsr); + assert( v->apCsr[0]!=0 ); + assert( v->apCsr[0]->eCurType==CURTYPE_BTREE ); + sqlite3VdbePreUpdateHook( + v, v->apCsr[0], SQLITE_DELETE, p->zDb, p->pTab, iKey, -1, p->iCol + ); + } +#endif + + rc = xCall(p->pCsr, iOffset+p->iOffset, n, z); + sqlite3BtreeLeaveCursor(p->pCsr); + if( rc==SQLITE_ABORT ){ + sqlite3VdbeFinalize(v); + p->pStmt = 0; + }else{ + v->rc = rc; + } + } + sqlite3Error(db, 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, sqlite3BtreePayloadChecked); +} + +/* +** 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; + ((Vdbe*)p->pStmt)->rc = SQLITE_OK; + rc = blobSeekToRow(p, iRow, &zErr); + if( rc!=SQLITE_OK ){ + sqlite3ErrorWithMsg(db, rc, (zErr ? "%s" : (char*)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 */ |