341 lines
10 KiB
C
Executable File
341 lines
10 KiB
C
Executable File
/*
|
|
** 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.
|
|
**
|
|
** $Id: vdbeblob.c,v 1.16 2007/08/30 01:19:59 drh Exp $
|
|
*/
|
|
|
|
#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 */
|
|
BtCursor *pCsr; /* Cursor pointing at blob row */
|
|
sqlite3_stmt *pStmt; /* Statement holding cursor open */
|
|
sqlite3 *db; /* The associated database */
|
|
};
|
|
|
|
/*
|
|
** 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_Callback.
|
|
** 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_Integer, 0, 0, 0}, /* 2: Database number */
|
|
|
|
/* One of the following two instructions is replaced by an
|
|
** OP_Noop before exection.
|
|
*/
|
|
{OP_OpenRead, 0, 0, 0}, /* 3: Open cursor 0 for reading */
|
|
{OP_OpenWrite, 0, 0, 0}, /* 4: Open cursor 0 for read/write */
|
|
{OP_SetNumColumns, 0, 0, 0}, /* 5: Num cols for cursor */
|
|
|
|
{OP_Variable, 1, 0, 0}, /* 6: Push the rowid to the stack */
|
|
{OP_NotExists, 0, 10, 0}, /* 7: Seek the cursor */
|
|
{OP_Column, 0, 0, 0}, /* 8 */
|
|
{OP_Callback, 0, 0, 0}, /* 9 */
|
|
{OP_Close, 0, 0, 0}, /* 10 */
|
|
{OP_Halt, 0, 0, 0}, /* 11 */
|
|
};
|
|
|
|
Vdbe *v = 0;
|
|
int rc = SQLITE_OK;
|
|
char zErr[128];
|
|
|
|
zErr[0] = 0;
|
|
sqlite3_mutex_enter(db->mutex);
|
|
do {
|
|
Parse sParse;
|
|
Table *pTab;
|
|
|
|
memset(&sParse, 0, sizeof(Parse));
|
|
sParse.db = db;
|
|
|
|
rc = sqlite3SafetyOn(db);
|
|
if( rc!=SQLITE_OK ){
|
|
sqlite3_mutex_leave(db->mutex);
|
|
return rc;
|
|
}
|
|
|
|
sqlite3BtreeEnterAll(db);
|
|
pTab = sqlite3LocateTable(&sParse, zTable, zDb);
|
|
if( !pTab ){
|
|
if( sParse.zErrMsg ){
|
|
sqlite3_snprintf(sizeof(zErr), zErr, "%s", sParse.zErrMsg);
|
|
}
|
|
sqlite3_free(sParse.zErrMsg);
|
|
rc = SQLITE_ERROR;
|
|
sqlite3SafetyOff(db);
|
|
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 ){
|
|
sqlite3_snprintf(sizeof(zErr), zErr, "no such column: \"%s\"", zColumn);
|
|
rc = SQLITE_ERROR;
|
|
sqlite3SafetyOff(db);
|
|
sqlite3BtreeLeaveAll(db);
|
|
goto blob_open_out;
|
|
}
|
|
|
|
/* If the value is being opened for writing, check that the
|
|
** column is not indexed. It is against the rules to open an
|
|
** indexed column for writing.
|
|
*/
|
|
if( flags ){
|
|
Index *pIdx;
|
|
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
|
|
int j;
|
|
for(j=0; j<pIdx->nColumn; j++){
|
|
if( pIdx->aiColumn[j]==iCol ){
|
|
sqlite3_snprintf(sizeof(zErr), zErr,
|
|
"cannot open indexed column for writing");
|
|
rc = SQLITE_ERROR;
|
|
sqlite3SafetyOff(db);
|
|
sqlite3BtreeLeaveAll(db);
|
|
goto blob_open_out;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
v = sqlite3VdbeCreate(db);
|
|
if( v ){
|
|
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 ? 1 : 0));
|
|
|
|
/* Configure the OP_VerifyCookie */
|
|
sqlite3VdbeChangeP1(v, 1, iDb);
|
|
sqlite3VdbeChangeP2(v, 1, pTab->pSchema->schema_cookie);
|
|
|
|
/* Make sure a mutex is held on the table to be accessed */
|
|
sqlite3VdbeUsesBtree(v, iDb);
|
|
|
|
/* Configure the db number pushed onto the stack */
|
|
sqlite3VdbeChangeP1(v, 2, iDb);
|
|
|
|
/* Remove either the OP_OpenWrite or OpenRead. Set the P2
|
|
** parameter of the other to pTab->tnum.
|
|
*/
|
|
sqlite3VdbeChangeToNoop(v, (flags ? 3 : 4), 1);
|
|
sqlite3VdbeChangeP2(v, (flags ? 4 : 3), pTab->tnum);
|
|
|
|
/* Configure the OP_SetNumColumns. 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.
|
|
*/
|
|
sqlite3VdbeChangeP2(v, 5, pTab->nCol+1);
|
|
if( !db->mallocFailed ){
|
|
sqlite3VdbeMakeReady(v, 1, 0, 1, 0);
|
|
}
|
|
}
|
|
|
|
sqlite3BtreeLeaveAll(db);
|
|
rc = sqlite3SafetyOff(db);
|
|
if( rc!=SQLITE_OK || db->mallocFailed ){
|
|
goto blob_open_out;
|
|
}
|
|
|
|
sqlite3_bind_int64((sqlite3_stmt *)v, 1, iRow);
|
|
rc = sqlite3_step((sqlite3_stmt *)v);
|
|
if( rc!=SQLITE_ROW ){
|
|
nAttempt++;
|
|
rc = sqlite3_finalize((sqlite3_stmt *)v);
|
|
sqlite3_snprintf(sizeof(zErr), zErr, sqlite3_errmsg(db));
|
|
v = 0;
|
|
}
|
|
} while( nAttempt<5 && rc==SQLITE_SCHEMA );
|
|
|
|
if( rc==SQLITE_ROW ){
|
|
/* The row-record has been opened successfully. Check that the
|
|
** column in question contains text or a blob. If it contains
|
|
** text, it is up to the caller to get the encoding right.
|
|
*/
|
|
Incrblob *pBlob;
|
|
u32 type = v->apCsr[0]->aType[iCol];
|
|
|
|
if( type<12 ){
|
|
sqlite3_snprintf(sizeof(zErr), zErr, "cannot open value of type %s",
|
|
type==0?"null": type==7?"real": "integer"
|
|
);
|
|
rc = SQLITE_ERROR;
|
|
goto blob_open_out;
|
|
}
|
|
pBlob = (Incrblob *)sqlite3DbMallocZero(db, sizeof(Incrblob));
|
|
if( db->mallocFailed ){
|
|
sqlite3_free(pBlob);
|
|
goto blob_open_out;
|
|
}
|
|
pBlob->flags = flags;
|
|
pBlob->pCsr = v->apCsr[0]->pCursor;
|
|
sqlite3BtreeEnterCursor(pBlob->pCsr);
|
|
sqlite3BtreeCacheOverflow(pBlob->pCsr);
|
|
sqlite3BtreeLeaveCursor(pBlob->pCsr);
|
|
pBlob->pStmt = (sqlite3_stmt *)v;
|
|
pBlob->iOffset = v->apCsr[0]->aOffset[iCol];
|
|
pBlob->nByte = sqlite3VdbeSerialTypeLen(type);
|
|
pBlob->db = db;
|
|
*ppBlob = (sqlite3_blob *)pBlob;
|
|
rc = SQLITE_OK;
|
|
}else if( rc==SQLITE_OK ){
|
|
sqlite3_snprintf(sizeof(zErr), zErr, "no such rowid: %lld", iRow);
|
|
rc = SQLITE_ERROR;
|
|
}
|
|
|
|
blob_open_out:
|
|
zErr[sizeof(zErr)-1] = '\0';
|
|
if( rc!=SQLITE_OK || db->mallocFailed ){
|
|
sqlite3_finalize((sqlite3_stmt *)v);
|
|
}
|
|
sqlite3Error(db, rc, (rc==SQLITE_OK?0:zErr));
|
|
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;
|
|
|
|
rc = sqlite3_finalize(p->pStmt);
|
|
sqlite3_free(p);
|
|
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 = p->db;
|
|
|
|
/* Request is out of range. Return a transient error. */
|
|
if( (iOffset+n)>p->nByte ){
|
|
return SQLITE_ERROR;
|
|
}
|
|
sqlite3_mutex_enter(db->mutex);
|
|
|
|
/* If there is no statement handle, then the blob-handle has
|
|
** already been invalidated. Return SQLITE_ABORT in this case.
|
|
*/
|
|
v = (Vdbe*)p->pStmt;
|
|
if( v==0 ){
|
|
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->nByte;
|
|
}
|
|
|
|
#endif /* #ifndef SQLITE_OMIT_INCRBLOB */
|