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authorDaniel Baumann <daniel.baumann@progress-linux.org>2023-10-17 09:30:20 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2023-10-17 09:30:20 +0000
commit386ccdd61e8256c8b21ee27ee2fc12438fc5ca98 (patch)
treec9fbcacdb01f029f46133a5ba7ecd610c2bcb041 /database/sqlite/dbdata.c
parentAdding upstream version 1.42.4. (diff)
downloadnetdata-386ccdd61e8256c8b21ee27ee2fc12438fc5ca98.tar.xz
netdata-386ccdd61e8256c8b21ee27ee2fc12438fc5ca98.zip
Adding upstream version 1.43.0.upstream/1.43.0
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'database/sqlite/dbdata.c')
-rw-r--r--database/sqlite/dbdata.c959
1 files changed, 959 insertions, 0 deletions
diff --git a/database/sqlite/dbdata.c b/database/sqlite/dbdata.c
new file mode 100644
index 000000000..1ad742e04
--- /dev/null
+++ b/database/sqlite/dbdata.c
@@ -0,0 +1,959 @@
+/*
+** 2019-04-17
+**
+** 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 an implementation of two eponymous virtual tables,
+** "sqlite_dbdata" and "sqlite_dbptr". Both modules require that the
+** "sqlite_dbpage" eponymous virtual table be available.
+**
+** SQLITE_DBDATA:
+** sqlite_dbdata is used to extract data directly from a database b-tree
+** page and its associated overflow pages, bypassing the b-tree layer.
+** The table schema is equivalent to:
+**
+** CREATE TABLE sqlite_dbdata(
+** pgno INTEGER,
+** cell INTEGER,
+** field INTEGER,
+** value ANY,
+** schema TEXT HIDDEN
+** );
+**
+** IMPORTANT: THE VIRTUAL TABLE SCHEMA ABOVE IS SUBJECT TO CHANGE. IN THE
+** FUTURE NEW NON-HIDDEN COLUMNS MAY BE ADDED BETWEEN "value" AND
+** "schema".
+**
+** Each page of the database is inspected. If it cannot be interpreted as
+** a b-tree page, or if it is a b-tree page containing 0 entries, the
+** sqlite_dbdata table contains no rows for that page. Otherwise, the
+** table contains one row for each field in the record associated with
+** each cell on the page. For intkey b-trees, the key value is stored in
+** field -1.
+**
+** For example, for the database:
+**
+** CREATE TABLE t1(a, b); -- root page is page 2
+** INSERT INTO t1(rowid, a, b) VALUES(5, 'v', 'five');
+** INSERT INTO t1(rowid, a, b) VALUES(10, 'x', 'ten');
+**
+** the sqlite_dbdata table contains, as well as from entries related to
+** page 1, content equivalent to:
+**
+** INSERT INTO sqlite_dbdata(pgno, cell, field, value) VALUES
+** (2, 0, -1, 5 ),
+** (2, 0, 0, 'v' ),
+** (2, 0, 1, 'five'),
+** (2, 1, -1, 10 ),
+** (2, 1, 0, 'x' ),
+** (2, 1, 1, 'ten' );
+**
+** If database corruption is encountered, this module does not report an
+** error. Instead, it attempts to extract as much data as possible and
+** ignores the corruption.
+**
+** SQLITE_DBPTR:
+** The sqlite_dbptr table has the following schema:
+**
+** CREATE TABLE sqlite_dbptr(
+** pgno INTEGER,
+** child INTEGER,
+** schema TEXT HIDDEN
+** );
+**
+** It contains one entry for each b-tree pointer between a parent and
+** child page in the database.
+*/
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+#if !defined(SQLITEINT_H)
+#include "sqlite3.h"
+
+typedef unsigned char u8;
+typedef unsigned int u32;
+
+#endif
+#include <string.h>
+#include <assert.h>
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+
+#define DBDATA_PADDING_BYTES 100
+
+typedef struct DbdataTable DbdataTable;
+typedef struct DbdataCursor DbdataCursor;
+
+/* Cursor object */
+struct DbdataCursor {
+ sqlite3_vtab_cursor base; /* Base class. Must be first */
+ sqlite3_stmt *pStmt; /* For fetching database pages */
+
+ int iPgno; /* Current page number */
+ u8 *aPage; /* Buffer containing page */
+ int nPage; /* Size of aPage[] in bytes */
+ int nCell; /* Number of cells on aPage[] */
+ int iCell; /* Current cell number */
+ int bOnePage; /* True to stop after one page */
+ int szDb;
+ sqlite3_int64 iRowid;
+
+ /* Only for the sqlite_dbdata table */
+ u8 *pRec; /* Buffer containing current record */
+ sqlite3_int64 nRec; /* Size of pRec[] in bytes */
+ sqlite3_int64 nHdr; /* Size of header in bytes */
+ int iField; /* Current field number */
+ u8 *pHdrPtr;
+ u8 *pPtr;
+ u32 enc; /* Text encoding */
+
+ sqlite3_int64 iIntkey; /* Integer key value */
+};
+
+/* Table object */
+struct DbdataTable {
+ sqlite3_vtab base; /* Base class. Must be first */
+ sqlite3 *db; /* The database connection */
+ sqlite3_stmt *pStmt; /* For fetching database pages */
+ int bPtr; /* True for sqlite3_dbptr table */
+};
+
+/* Column and schema definitions for sqlite_dbdata */
+#define DBDATA_COLUMN_PGNO 0
+#define DBDATA_COLUMN_CELL 1
+#define DBDATA_COLUMN_FIELD 2
+#define DBDATA_COLUMN_VALUE 3
+#define DBDATA_COLUMN_SCHEMA 4
+#define DBDATA_SCHEMA \
+ "CREATE TABLE x(" \
+ " pgno INTEGER," \
+ " cell INTEGER," \
+ " field INTEGER," \
+ " value ANY," \
+ " schema TEXT HIDDEN" \
+ ")"
+
+/* Column and schema definitions for sqlite_dbptr */
+#define DBPTR_COLUMN_PGNO 0
+#define DBPTR_COLUMN_CHILD 1
+#define DBPTR_COLUMN_SCHEMA 2
+#define DBPTR_SCHEMA \
+ "CREATE TABLE x(" \
+ " pgno INTEGER," \
+ " child INTEGER," \
+ " schema TEXT HIDDEN" \
+ ")"
+
+/*
+** Connect to an sqlite_dbdata (pAux==0) or sqlite_dbptr (pAux!=0) virtual
+** table.
+*/
+static int dbdataConnect(
+ sqlite3 *db,
+ void *pAux,
+ int argc, const char *const*argv,
+ sqlite3_vtab **ppVtab,
+ char **pzErr
+){
+ DbdataTable *pTab = 0;
+ int rc = sqlite3_declare_vtab(db, pAux ? DBPTR_SCHEMA : DBDATA_SCHEMA);
+
+ (void)argc;
+ (void)argv;
+ (void)pzErr;
+ sqlite3_vtab_config(db, SQLITE_VTAB_USES_ALL_SCHEMAS);
+ if( rc==SQLITE_OK ){
+ pTab = (DbdataTable*)sqlite3_malloc64(sizeof(DbdataTable));
+ if( pTab==0 ){
+ rc = SQLITE_NOMEM;
+ }else{
+ memset(pTab, 0, sizeof(DbdataTable));
+ pTab->db = db;
+ pTab->bPtr = (pAux!=0);
+ }
+ }
+
+ *ppVtab = (sqlite3_vtab*)pTab;
+ return rc;
+}
+
+/*
+** Disconnect from or destroy a sqlite_dbdata or sqlite_dbptr virtual table.
+*/
+static int dbdataDisconnect(sqlite3_vtab *pVtab){
+ DbdataTable *pTab = (DbdataTable*)pVtab;
+ if( pTab ){
+ sqlite3_finalize(pTab->pStmt);
+ sqlite3_free(pVtab);
+ }
+ return SQLITE_OK;
+}
+
+/*
+** This function interprets two types of constraints:
+**
+** schema=?
+** pgno=?
+**
+** If neither are present, idxNum is set to 0. If schema=? is present,
+** the 0x01 bit in idxNum is set. If pgno=? is present, the 0x02 bit
+** in idxNum is set.
+**
+** If both parameters are present, schema is in position 0 and pgno in
+** position 1.
+*/
+static int dbdataBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdx){
+ DbdataTable *pTab = (DbdataTable*)tab;
+ int i;
+ int iSchema = -1;
+ int iPgno = -1;
+ int colSchema = (pTab->bPtr ? DBPTR_COLUMN_SCHEMA : DBDATA_COLUMN_SCHEMA);
+
+ for(i=0; i<pIdx->nConstraint; i++){
+ struct sqlite3_index_constraint *p = &pIdx->aConstraint[i];
+ if( p->op==SQLITE_INDEX_CONSTRAINT_EQ ){
+ if( p->iColumn==colSchema ){
+ if( p->usable==0 ) return SQLITE_CONSTRAINT;
+ iSchema = i;
+ }
+ if( p->iColumn==DBDATA_COLUMN_PGNO && p->usable ){
+ iPgno = i;
+ }
+ }
+ }
+
+ if( iSchema>=0 ){
+ pIdx->aConstraintUsage[iSchema].argvIndex = 1;
+ pIdx->aConstraintUsage[iSchema].omit = 1;
+ }
+ if( iPgno>=0 ){
+ pIdx->aConstraintUsage[iPgno].argvIndex = 1 + (iSchema>=0);
+ pIdx->aConstraintUsage[iPgno].omit = 1;
+ pIdx->estimatedCost = 100;
+ pIdx->estimatedRows = 50;
+
+ if( pTab->bPtr==0 && pIdx->nOrderBy && pIdx->aOrderBy[0].desc==0 ){
+ int iCol = pIdx->aOrderBy[0].iColumn;
+ if( pIdx->nOrderBy==1 ){
+ pIdx->orderByConsumed = (iCol==0 || iCol==1);
+ }else if( pIdx->nOrderBy==2 && pIdx->aOrderBy[1].desc==0 && iCol==0 ){
+ pIdx->orderByConsumed = (pIdx->aOrderBy[1].iColumn==1);
+ }
+ }
+
+ }else{
+ pIdx->estimatedCost = 100000000;
+ pIdx->estimatedRows = 1000000000;
+ }
+ pIdx->idxNum = (iSchema>=0 ? 0x01 : 0x00) | (iPgno>=0 ? 0x02 : 0x00);
+ return SQLITE_OK;
+}
+
+/*
+** Open a new sqlite_dbdata or sqlite_dbptr cursor.
+*/
+static int dbdataOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){
+ DbdataCursor *pCsr;
+
+ pCsr = (DbdataCursor*)sqlite3_malloc64(sizeof(DbdataCursor));
+ if( pCsr==0 ){
+ return SQLITE_NOMEM;
+ }else{
+ memset(pCsr, 0, sizeof(DbdataCursor));
+ pCsr->base.pVtab = pVTab;
+ }
+
+ *ppCursor = (sqlite3_vtab_cursor *)pCsr;
+ return SQLITE_OK;
+}
+
+/*
+** Restore a cursor object to the state it was in when first allocated
+** by dbdataOpen().
+*/
+static void dbdataResetCursor(DbdataCursor *pCsr){
+ DbdataTable *pTab = (DbdataTable*)(pCsr->base.pVtab);
+ if( pTab->pStmt==0 ){
+ pTab->pStmt = pCsr->pStmt;
+ }else{
+ sqlite3_finalize(pCsr->pStmt);
+ }
+ pCsr->pStmt = 0;
+ pCsr->iPgno = 1;
+ pCsr->iCell = 0;
+ pCsr->iField = 0;
+ pCsr->bOnePage = 0;
+ sqlite3_free(pCsr->aPage);
+ sqlite3_free(pCsr->pRec);
+ pCsr->pRec = 0;
+ pCsr->aPage = 0;
+}
+
+/*
+** Close an sqlite_dbdata or sqlite_dbptr cursor.
+*/
+static int dbdataClose(sqlite3_vtab_cursor *pCursor){
+ DbdataCursor *pCsr = (DbdataCursor*)pCursor;
+ dbdataResetCursor(pCsr);
+ sqlite3_free(pCsr);
+ return SQLITE_OK;
+}
+
+/*
+** Utility methods to decode 16 and 32-bit big-endian unsigned integers.
+*/
+static u32 get_uint16(unsigned char *a){
+ return (a[0]<<8)|a[1];
+}
+static u32 get_uint32(unsigned char *a){
+ return ((u32)a[0]<<24)
+ | ((u32)a[1]<<16)
+ | ((u32)a[2]<<8)
+ | ((u32)a[3]);
+}
+
+/*
+** Load page pgno from the database via the sqlite_dbpage virtual table.
+** If successful, set (*ppPage) to point to a buffer containing the page
+** data, (*pnPage) to the size of that buffer in bytes and return
+** SQLITE_OK. In this case it is the responsibility of the caller to
+** eventually free the buffer using sqlite3_free().
+**
+** Or, if an error occurs, set both (*ppPage) and (*pnPage) to 0 and
+** return an SQLite error code.
+*/
+static int dbdataLoadPage(
+ DbdataCursor *pCsr, /* Cursor object */
+ u32 pgno, /* Page number of page to load */
+ u8 **ppPage, /* OUT: pointer to page buffer */
+ int *pnPage /* OUT: Size of (*ppPage) in bytes */
+){
+ int rc2;
+ int rc = SQLITE_OK;
+ sqlite3_stmt *pStmt = pCsr->pStmt;
+
+ *ppPage = 0;
+ *pnPage = 0;
+ if( pgno>0 ){
+ sqlite3_bind_int64(pStmt, 2, pgno);
+ if( SQLITE_ROW==sqlite3_step(pStmt) ){
+ int nCopy = sqlite3_column_bytes(pStmt, 0);
+ if( nCopy>0 ){
+ u8 *pPage;
+ pPage = (u8*)sqlite3_malloc64(nCopy + DBDATA_PADDING_BYTES);
+ if( pPage==0 ){
+ rc = SQLITE_NOMEM;
+ }else{
+ const u8 *pCopy = sqlite3_column_blob(pStmt, 0);
+ memcpy(pPage, pCopy, nCopy);
+ memset(&pPage[nCopy], 0, DBDATA_PADDING_BYTES);
+ }
+ *ppPage = pPage;
+ *pnPage = nCopy;
+ }
+ }
+ rc2 = sqlite3_reset(pStmt);
+ if( rc==SQLITE_OK ) rc = rc2;
+ }
+
+ return rc;
+}
+
+/*
+** Read a varint. Put the value in *pVal and return the number of bytes.
+*/
+static int dbdataGetVarint(const u8 *z, sqlite3_int64 *pVal){
+ sqlite3_uint64 u = 0;
+ int i;
+ for(i=0; i<8; i++){
+ u = (u<<7) + (z[i]&0x7f);
+ if( (z[i]&0x80)==0 ){ *pVal = (sqlite3_int64)u; return i+1; }
+ }
+ u = (u<<8) + (z[i]&0xff);
+ *pVal = (sqlite3_int64)u;
+ return 9;
+}
+
+/*
+** Like dbdataGetVarint(), but set the output to 0 if it is less than 0
+** or greater than 0xFFFFFFFF. This can be used for all varints in an
+** SQLite database except for key values in intkey tables.
+*/
+static int dbdataGetVarintU32(const u8 *z, sqlite3_int64 *pVal){
+ sqlite3_int64 val;
+ int nRet = dbdataGetVarint(z, &val);
+ if( val<0 || val>0xFFFFFFFF ) val = 0;
+ *pVal = val;
+ return nRet;
+}
+
+/*
+** Return the number of bytes of space used by an SQLite value of type
+** eType.
+*/
+static int dbdataValueBytes(int eType){
+ switch( eType ){
+ case 0: case 8: case 9:
+ case 10: case 11:
+ return 0;
+ case 1:
+ return 1;
+ case 2:
+ return 2;
+ case 3:
+ return 3;
+ case 4:
+ return 4;
+ case 5:
+ return 6;
+ case 6:
+ case 7:
+ return 8;
+ default:
+ if( eType>0 ){
+ return ((eType-12) / 2);
+ }
+ return 0;
+ }
+}
+
+/*
+** Load a value of type eType from buffer pData and use it to set the
+** result of context object pCtx.
+*/
+static void dbdataValue(
+ sqlite3_context *pCtx,
+ u32 enc,
+ int eType,
+ u8 *pData,
+ sqlite3_int64 nData
+){
+ if( eType>=0 && dbdataValueBytes(eType)<=nData ){
+ switch( eType ){
+ case 0:
+ case 10:
+ case 11:
+ sqlite3_result_null(pCtx);
+ break;
+
+ case 8:
+ sqlite3_result_int(pCtx, 0);
+ break;
+ case 9:
+ sqlite3_result_int(pCtx, 1);
+ break;
+
+ case 1: case 2: case 3: case 4: case 5: case 6: case 7: {
+ sqlite3_uint64 v = (signed char)pData[0];
+ pData++;
+ switch( eType ){
+ case 7:
+ case 6: v = (v<<16) + (pData[0]<<8) + pData[1]; pData += 2;
+ case 5: v = (v<<16) + (pData[0]<<8) + pData[1]; pData += 2;
+ case 4: v = (v<<8) + pData[0]; pData++;
+ case 3: v = (v<<8) + pData[0]; pData++;
+ case 2: v = (v<<8) + pData[0]; pData++;
+ }
+
+ if( eType==7 ){
+ double r;
+ memcpy(&r, &v, sizeof(r));
+ sqlite3_result_double(pCtx, r);
+ }else{
+ sqlite3_result_int64(pCtx, (sqlite3_int64)v);
+ }
+ break;
+ }
+
+ default: {
+ int n = ((eType-12) / 2);
+ if( eType % 2 ){
+ switch( enc ){
+#ifndef SQLITE_OMIT_UTF16
+ case SQLITE_UTF16BE:
+ sqlite3_result_text16be(pCtx, (void*)pData, n, SQLITE_TRANSIENT);
+ break;
+ case SQLITE_UTF16LE:
+ sqlite3_result_text16le(pCtx, (void*)pData, n, SQLITE_TRANSIENT);
+ break;
+#endif
+ default:
+ sqlite3_result_text(pCtx, (char*)pData, n, SQLITE_TRANSIENT);
+ break;
+ }
+ }else{
+ sqlite3_result_blob(pCtx, pData, n, SQLITE_TRANSIENT);
+ }
+ }
+ }
+ }
+}
+
+/*
+** Move an sqlite_dbdata or sqlite_dbptr cursor to the next entry.
+*/
+static int dbdataNext(sqlite3_vtab_cursor *pCursor){
+ DbdataCursor *pCsr = (DbdataCursor*)pCursor;
+ DbdataTable *pTab = (DbdataTable*)pCursor->pVtab;
+
+ pCsr->iRowid++;
+ while( 1 ){
+ int rc;
+ int iOff = (pCsr->iPgno==1 ? 100 : 0);
+ int bNextPage = 0;
+
+ if( pCsr->aPage==0 ){
+ while( 1 ){
+ if( pCsr->bOnePage==0 && pCsr->iPgno>pCsr->szDb ) return SQLITE_OK;
+ rc = dbdataLoadPage(pCsr, pCsr->iPgno, &pCsr->aPage, &pCsr->nPage);
+ if( rc!=SQLITE_OK ) return rc;
+ if( pCsr->aPage && pCsr->nPage>=256 ) break;
+ sqlite3_free(pCsr->aPage);
+ pCsr->aPage = 0;
+ if( pCsr->bOnePage ) return SQLITE_OK;
+ pCsr->iPgno++;
+ }
+
+ assert( iOff+3+2<=pCsr->nPage );
+ pCsr->iCell = pTab->bPtr ? -2 : 0;
+ pCsr->nCell = get_uint16(&pCsr->aPage[iOff+3]);
+ }
+
+ if( pTab->bPtr ){
+ if( pCsr->aPage[iOff]!=0x02 && pCsr->aPage[iOff]!=0x05 ){
+ pCsr->iCell = pCsr->nCell;
+ }
+ pCsr->iCell++;
+ if( pCsr->iCell>=pCsr->nCell ){
+ sqlite3_free(pCsr->aPage);
+ pCsr->aPage = 0;
+ if( pCsr->bOnePage ) return SQLITE_OK;
+ pCsr->iPgno++;
+ }else{
+ return SQLITE_OK;
+ }
+ }else{
+ /* If there is no record loaded, load it now. */
+ if( pCsr->pRec==0 ){
+ int bHasRowid = 0;
+ int nPointer = 0;
+ sqlite3_int64 nPayload = 0;
+ sqlite3_int64 nHdr = 0;
+ int iHdr;
+ int U, X;
+ int nLocal;
+
+ switch( pCsr->aPage[iOff] ){
+ case 0x02:
+ nPointer = 4;
+ break;
+ case 0x0a:
+ break;
+ case 0x0d:
+ bHasRowid = 1;
+ break;
+ default:
+ /* This is not a b-tree page with records on it. Continue. */
+ pCsr->iCell = pCsr->nCell;
+ break;
+ }
+
+ if( pCsr->iCell>=pCsr->nCell ){
+ bNextPage = 1;
+ }else{
+
+ iOff += 8 + nPointer + pCsr->iCell*2;
+ if( iOff>pCsr->nPage ){
+ bNextPage = 1;
+ }else{
+ iOff = get_uint16(&pCsr->aPage[iOff]);
+ }
+
+ /* For an interior node cell, skip past the child-page number */
+ iOff += nPointer;
+
+ /* Load the "byte of payload including overflow" field */
+ if( bNextPage || iOff>pCsr->nPage ){
+ bNextPage = 1;
+ }else{
+ iOff += dbdataGetVarintU32(&pCsr->aPage[iOff], &nPayload);
+ }
+
+ /* If this is a leaf intkey cell, load the rowid */
+ if( bHasRowid && !bNextPage && iOff<pCsr->nPage ){
+ iOff += dbdataGetVarint(&pCsr->aPage[iOff], &pCsr->iIntkey);
+ }
+
+ /* Figure out how much data to read from the local page */
+ U = pCsr->nPage;
+ if( bHasRowid ){
+ X = U-35;
+ }else{
+ X = ((U-12)*64/255)-23;
+ }
+ if( nPayload<=X ){
+ nLocal = nPayload;
+ }else{
+ int M, K;
+ M = ((U-12)*32/255)-23;
+ K = M+((nPayload-M)%(U-4));
+ if( K<=X ){
+ nLocal = K;
+ }else{
+ nLocal = M;
+ }
+ }
+
+ if( bNextPage || nLocal+iOff>pCsr->nPage ){
+ bNextPage = 1;
+ }else{
+
+ /* Allocate space for payload. And a bit more to catch small buffer
+ ** overruns caused by attempting to read a varint or similar from
+ ** near the end of a corrupt record. */
+ pCsr->pRec = (u8*)sqlite3_malloc64(nPayload+DBDATA_PADDING_BYTES);
+ if( pCsr->pRec==0 ) return SQLITE_NOMEM;
+ memset(pCsr->pRec, 0, nPayload+DBDATA_PADDING_BYTES);
+ pCsr->nRec = nPayload;
+
+ /* Load the nLocal bytes of payload */
+ memcpy(pCsr->pRec, &pCsr->aPage[iOff], nLocal);
+ iOff += nLocal;
+
+ /* Load content from overflow pages */
+ if( nPayload>nLocal ){
+ sqlite3_int64 nRem = nPayload - nLocal;
+ u32 pgnoOvfl = get_uint32(&pCsr->aPage[iOff]);
+ while( nRem>0 ){
+ u8 *aOvfl = 0;
+ int nOvfl = 0;
+ int nCopy;
+ rc = dbdataLoadPage(pCsr, pgnoOvfl, &aOvfl, &nOvfl);
+ assert( rc!=SQLITE_OK || aOvfl==0 || nOvfl==pCsr->nPage );
+ if( rc!=SQLITE_OK ) return rc;
+ if( aOvfl==0 ) break;
+
+ nCopy = U-4;
+ if( nCopy>nRem ) nCopy = nRem;
+ memcpy(&pCsr->pRec[nPayload-nRem], &aOvfl[4], nCopy);
+ nRem -= nCopy;
+
+ pgnoOvfl = get_uint32(aOvfl);
+ sqlite3_free(aOvfl);
+ }
+ }
+
+ iHdr = dbdataGetVarintU32(pCsr->pRec, &nHdr);
+ if( nHdr>nPayload ) nHdr = 0;
+ pCsr->nHdr = nHdr;
+ pCsr->pHdrPtr = &pCsr->pRec[iHdr];
+ pCsr->pPtr = &pCsr->pRec[pCsr->nHdr];
+ pCsr->iField = (bHasRowid ? -1 : 0);
+ }
+ }
+ }else{
+ pCsr->iField++;
+ if( pCsr->iField>0 ){
+ sqlite3_int64 iType;
+ if( pCsr->pHdrPtr>&pCsr->pRec[pCsr->nRec] ){
+ bNextPage = 1;
+ }else{
+ int szField = 0;
+ pCsr->pHdrPtr += dbdataGetVarintU32(pCsr->pHdrPtr, &iType);
+ szField = dbdataValueBytes(iType);
+ if( (pCsr->nRec - (pCsr->pPtr - pCsr->pRec))<szField ){
+ pCsr->pPtr = &pCsr->pRec[pCsr->nRec];
+ }else{
+ pCsr->pPtr += szField;
+ }
+ }
+ }
+ }
+
+ if( bNextPage ){
+ sqlite3_free(pCsr->aPage);
+ sqlite3_free(pCsr->pRec);
+ pCsr->aPage = 0;
+ pCsr->pRec = 0;
+ if( pCsr->bOnePage ) return SQLITE_OK;
+ pCsr->iPgno++;
+ }else{
+ if( pCsr->iField<0 || pCsr->pHdrPtr<&pCsr->pRec[pCsr->nHdr] ){
+ return SQLITE_OK;
+ }
+
+ /* Advance to the next cell. The next iteration of the loop will load
+ ** the record and so on. */
+ sqlite3_free(pCsr->pRec);
+ pCsr->pRec = 0;
+ pCsr->iCell++;
+ }
+ }
+ }
+
+ assert( !"can't get here" );
+ return SQLITE_OK;
+}
+
+/*
+** Return true if the cursor is at EOF.
+*/
+static int dbdataEof(sqlite3_vtab_cursor *pCursor){
+ DbdataCursor *pCsr = (DbdataCursor*)pCursor;
+ return pCsr->aPage==0;
+}
+
+/*
+** Return true if nul-terminated string zSchema ends in "()". Or false
+** otherwise.
+*/
+static int dbdataIsFunction(const char *zSchema){
+ size_t n = strlen(zSchema);
+ if( n>2 && zSchema[n-2]=='(' && zSchema[n-1]==')' ){
+ return (int)n-2;
+ }
+ return 0;
+}
+
+/*
+** Determine the size in pages of database zSchema (where zSchema is
+** "main", "temp" or the name of an attached database) and set
+** pCsr->szDb accordingly. If successful, return SQLITE_OK. Otherwise,
+** an SQLite error code.
+*/
+static int dbdataDbsize(DbdataCursor *pCsr, const char *zSchema){
+ DbdataTable *pTab = (DbdataTable*)pCsr->base.pVtab;
+ char *zSql = 0;
+ int rc, rc2;
+ int nFunc = 0;
+ sqlite3_stmt *pStmt = 0;
+
+ if( (nFunc = dbdataIsFunction(zSchema))>0 ){
+ zSql = sqlite3_mprintf("SELECT %.*s(0)", nFunc, zSchema);
+ }else{
+ zSql = sqlite3_mprintf("PRAGMA %Q.page_count", zSchema);
+ }
+ if( zSql==0 ) return SQLITE_NOMEM;
+
+ rc = sqlite3_prepare_v2(pTab->db, zSql, -1, &pStmt, 0);
+ sqlite3_free(zSql);
+ if( rc==SQLITE_OK && sqlite3_step(pStmt)==SQLITE_ROW ){
+ pCsr->szDb = sqlite3_column_int(pStmt, 0);
+ }
+ rc2 = sqlite3_finalize(pStmt);
+ if( rc==SQLITE_OK ) rc = rc2;
+ return rc;
+}
+
+/*
+** Attempt to figure out the encoding of the database by retrieving page 1
+** and inspecting the header field. If successful, set the pCsr->enc variable
+** and return SQLITE_OK. Otherwise, return an SQLite error code.
+*/
+static int dbdataGetEncoding(DbdataCursor *pCsr){
+ int rc = SQLITE_OK;
+ int nPg1 = 0;
+ u8 *aPg1 = 0;
+ rc = dbdataLoadPage(pCsr, 1, &aPg1, &nPg1);
+ if( rc==SQLITE_OK && nPg1>=(56+4) ){
+ pCsr->enc = get_uint32(&aPg1[56]);
+ }
+ sqlite3_free(aPg1);
+ return rc;
+}
+
+
+/*
+** xFilter method for sqlite_dbdata and sqlite_dbptr.
+*/
+static int dbdataFilter(
+ sqlite3_vtab_cursor *pCursor,
+ int idxNum, const char *idxStr,
+ int argc, sqlite3_value **argv
+){
+ DbdataCursor *pCsr = (DbdataCursor*)pCursor;
+ DbdataTable *pTab = (DbdataTable*)pCursor->pVtab;
+ int rc = SQLITE_OK;
+ const char *zSchema = "main";
+ (void)idxStr;
+ (void)argc;
+
+ dbdataResetCursor(pCsr);
+ assert( pCsr->iPgno==1 );
+ if( idxNum & 0x01 ){
+ zSchema = (const char*)sqlite3_value_text(argv[0]);
+ if( zSchema==0 ) zSchema = "";
+ }
+ if( idxNum & 0x02 ){
+ pCsr->iPgno = sqlite3_value_int(argv[(idxNum & 0x01)]);
+ pCsr->bOnePage = 1;
+ }else{
+ rc = dbdataDbsize(pCsr, zSchema);
+ }
+
+ if( rc==SQLITE_OK ){
+ int nFunc = 0;
+ if( pTab->pStmt ){
+ pCsr->pStmt = pTab->pStmt;
+ pTab->pStmt = 0;
+ }else if( (nFunc = dbdataIsFunction(zSchema))>0 ){
+ char *zSql = sqlite3_mprintf("SELECT %.*s(?2)", nFunc, zSchema);
+ if( zSql==0 ){
+ rc = SQLITE_NOMEM;
+ }else{
+ rc = sqlite3_prepare_v2(pTab->db, zSql, -1, &pCsr->pStmt, 0);
+ sqlite3_free(zSql);
+ }
+ }else{
+ rc = sqlite3_prepare_v2(pTab->db,
+ "SELECT data FROM sqlite_dbpage(?) WHERE pgno=?", -1,
+ &pCsr->pStmt, 0
+ );
+ }
+ }
+ if( rc==SQLITE_OK ){
+ rc = sqlite3_bind_text(pCsr->pStmt, 1, zSchema, -1, SQLITE_TRANSIENT);
+ }
+
+ /* Try to determine the encoding of the db by inspecting the header
+ ** field on page 1. */
+ if( rc==SQLITE_OK ){
+ rc = dbdataGetEncoding(pCsr);
+ }
+
+ if( rc!=SQLITE_OK ){
+ pTab->base.zErrMsg = sqlite3_mprintf("%s", sqlite3_errmsg(pTab->db));
+ }
+
+ if( rc==SQLITE_OK ){
+ rc = dbdataNext(pCursor);
+ }
+ return rc;
+}
+
+/*
+** Return a column for the sqlite_dbdata or sqlite_dbptr table.
+*/
+static int dbdataColumn(
+ sqlite3_vtab_cursor *pCursor,
+ sqlite3_context *ctx,
+ int i
+){
+ DbdataCursor *pCsr = (DbdataCursor*)pCursor;
+ DbdataTable *pTab = (DbdataTable*)pCursor->pVtab;
+ if( pTab->bPtr ){
+ switch( i ){
+ case DBPTR_COLUMN_PGNO:
+ sqlite3_result_int64(ctx, pCsr->iPgno);
+ break;
+ case DBPTR_COLUMN_CHILD: {
+ int iOff = pCsr->iPgno==1 ? 100 : 0;
+ if( pCsr->iCell<0 ){
+ iOff += 8;
+ }else{
+ iOff += 12 + pCsr->iCell*2;
+ if( iOff>pCsr->nPage ) return SQLITE_OK;
+ iOff = get_uint16(&pCsr->aPage[iOff]);
+ }
+ if( iOff<=pCsr->nPage ){
+ sqlite3_result_int64(ctx, get_uint32(&pCsr->aPage[iOff]));
+ }
+ break;
+ }
+ }
+ }else{
+ switch( i ){
+ case DBDATA_COLUMN_PGNO:
+ sqlite3_result_int64(ctx, pCsr->iPgno);
+ break;
+ case DBDATA_COLUMN_CELL:
+ sqlite3_result_int(ctx, pCsr->iCell);
+ break;
+ case DBDATA_COLUMN_FIELD:
+ sqlite3_result_int(ctx, pCsr->iField);
+ break;
+ case DBDATA_COLUMN_VALUE: {
+ if( pCsr->iField<0 ){
+ sqlite3_result_int64(ctx, pCsr->iIntkey);
+ }else if( &pCsr->pRec[pCsr->nRec] >= pCsr->pPtr ){
+ sqlite3_int64 iType;
+ dbdataGetVarintU32(pCsr->pHdrPtr, &iType);
+ dbdataValue(
+ ctx, pCsr->enc, iType, pCsr->pPtr,
+ &pCsr->pRec[pCsr->nRec] - pCsr->pPtr
+ );
+ }
+ break;
+ }
+ }
+ }
+ return SQLITE_OK;
+}
+
+/*
+** Return the rowid for an sqlite_dbdata or sqlite_dptr table.
+*/
+static int dbdataRowid(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
+ DbdataCursor *pCsr = (DbdataCursor*)pCursor;
+ *pRowid = pCsr->iRowid;
+ return SQLITE_OK;
+}
+
+
+/*
+** Invoke this routine to register the "sqlite_dbdata" virtual table module
+*/
+static int sqlite3DbdataRegister(sqlite3 *db){
+ static sqlite3_module dbdata_module = {
+ 0, /* iVersion */
+ 0, /* xCreate */
+ dbdataConnect, /* xConnect */
+ dbdataBestIndex, /* xBestIndex */
+ dbdataDisconnect, /* xDisconnect */
+ 0, /* xDestroy */
+ dbdataOpen, /* xOpen - open a cursor */
+ dbdataClose, /* xClose - close a cursor */
+ dbdataFilter, /* xFilter - configure scan constraints */
+ dbdataNext, /* xNext - advance a cursor */
+ dbdataEof, /* xEof - check for end of scan */
+ dbdataColumn, /* xColumn - read data */
+ dbdataRowid, /* xRowid - read data */
+ 0, /* xUpdate */
+ 0, /* xBegin */
+ 0, /* xSync */
+ 0, /* xCommit */
+ 0, /* xRollback */
+ 0, /* xFindMethod */
+ 0, /* xRename */
+ 0, /* xSavepoint */
+ 0, /* xRelease */
+ 0, /* xRollbackTo */
+ 0 /* xShadowName */
+ };
+
+ int rc = sqlite3_create_module(db, "sqlite_dbdata", &dbdata_module, 0);
+ if( rc==SQLITE_OK ){
+ rc = sqlite3_create_module(db, "sqlite_dbptr", &dbdata_module, (void*)1);
+ }
+ return rc;
+}
+
+int sqlite3_dbdata_init(
+ sqlite3 *db,
+ char **pzErrMsg,
+ const sqlite3_api_routines *pApi
+){
+ (void)pzErrMsg;
+ return sqlite3DbdataRegister(db);
+}
+
+#endif /* ifndef SQLITE_OMIT_VIRTUALTABLE */
+#pragma GCC diagnostic pop