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-rw-r--r--src/dbpage.c329
-rw-r--r--src/main.c6
-rw-r--r--src/shell.c.in18
-rw-r--r--src/sqliteInt.h3
4 files changed, 349 insertions, 7 deletions
diff --git a/src/dbpage.c b/src/dbpage.c
new file mode 100644
index 000000000..d21c5b6df
--- /dev/null
+++ b/src/dbpage.c
@@ -0,0 +1,329 @@
+/*
+** 2017-10-11
+**
+** 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 the "sqlite_dbpage" virtual table.
+**
+** The sqlite_dbpage virtual table is used to read or write whole raw
+** pages of the database file. The pager interface is used so that
+** uncommitted changes and changes recorded in the WAL file are correctly
+** retrieved.
+**
+** Usage example:
+**
+** SELECT data FROM sqlite_dbpage('aux1') WHERE pgno=123;
+**
+** This is an eponymous virtual table so it does not need to be created before
+** use. The optional argument to the sqlite_dbpage() table name is the
+** schema for the database file that is to be read. The default schema is
+** "main".
+**
+** The data field of sqlite_dbpage table can be updated. The new
+** value must be a BLOB which is the correct page size, otherwise the
+** update fails. Rows may not be deleted or inserted.
+*/
+
+#include "sqliteInt.h" /* Requires access to internal data structures */
+#if (defined(SQLITE_ENABLE_DBPAGE_VTAB) || defined(SQLITE_TEST)) \
+ && !defined(SQLITE_OMIT_VIRTUALTABLE)
+
+typedef struct DbpageTable DbpageTable;
+typedef struct DbpageCursor DbpageCursor;
+
+struct DbpageCursor {
+ sqlite3_vtab_cursor base; /* Base class. Must be first */
+ int pgno; /* Current page number */
+ int mxPgno; /* Last page to visit on this scan */
+};
+
+struct DbpageTable {
+ sqlite3_vtab base; /* Base class. Must be first */
+ sqlite3 *db; /* The database */
+ Pager *pPager; /* Pager being read/written */
+ int iDb; /* Index of database to analyze */
+ int szPage; /* Size of each page in bytes */
+ int nPage; /* Number of pages in the file */
+};
+
+/*
+** Connect to or create a dbpagevfs virtual table.
+*/
+static int dbpageConnect(
+ sqlite3 *db,
+ void *pAux,
+ int argc, const char *const*argv,
+ sqlite3_vtab **ppVtab,
+ char **pzErr
+){
+ DbpageTable *pTab = 0;
+ int rc = SQLITE_OK;
+ int iDb;
+
+ if( argc>=4 ){
+ Token nm;
+ sqlite3TokenInit(&nm, (char*)argv[3]);
+ iDb = sqlite3FindDb(db, &nm);
+ if( iDb<0 ){
+ *pzErr = sqlite3_mprintf("no such schema: %s", argv[3]);
+ return SQLITE_ERROR;
+ }
+ }else{
+ iDb = 0;
+ }
+ rc = sqlite3_declare_vtab(db,
+ "CREATE TABLE x(pgno INTEGER PRIMARY KEY, data BLOB, schema HIDDEN)");
+ if( rc==SQLITE_OK ){
+ pTab = (DbpageTable *)sqlite3_malloc64(sizeof(DbpageTable));
+ if( pTab==0 ) rc = SQLITE_NOMEM_BKPT;
+ }
+
+ assert( rc==SQLITE_OK || pTab==0 );
+ if( rc==SQLITE_OK ){
+ Btree *pBt = db->aDb[iDb].pBt;
+ memset(pTab, 0, sizeof(DbpageTable));
+ pTab->db = db;
+ pTab->iDb = iDb;
+ pTab->pPager = pBt ? sqlite3BtreePager(pBt) : 0;
+ }
+
+ *ppVtab = (sqlite3_vtab*)pTab;
+ return rc;
+}
+
+/*
+** Disconnect from or destroy a dbpagevfs virtual table.
+*/
+static int dbpageDisconnect(sqlite3_vtab *pVtab){
+ sqlite3_free(pVtab);
+ return SQLITE_OK;
+}
+
+/*
+** idxNum:
+**
+** 0 full table scan
+** 1 pgno=?1
+*/
+static int dbpageBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
+ int i;
+ pIdxInfo->estimatedCost = 1.0e6; /* Initial cost estimate */
+ for(i=0; i<pIdxInfo->nConstraint; i++){
+ struct sqlite3_index_constraint *p = &pIdxInfo->aConstraint[i];
+ if( p->usable && p->iColumn<=0 && p->op==SQLITE_INDEX_CONSTRAINT_EQ ){
+ pIdxInfo->estimatedRows = 1;
+ pIdxInfo->idxFlags = SQLITE_INDEX_SCAN_UNIQUE;
+ pIdxInfo->estimatedCost = 1.0;
+ pIdxInfo->idxNum = 1;
+ pIdxInfo->aConstraintUsage[i].argvIndex = 1;
+ pIdxInfo->aConstraintUsage[i].omit = 1;
+ break;
+ }
+ }
+ if( pIdxInfo->nOrderBy>=1
+ && pIdxInfo->aOrderBy[0].iColumn<=0
+ && pIdxInfo->aOrderBy[0].desc==0
+ ){
+ pIdxInfo->orderByConsumed = 1;
+ }
+ return SQLITE_OK;
+}
+
+/*
+** Open a new dbpagevfs cursor.
+*/
+static int dbpageOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){
+ DbpageCursor *pCsr;
+
+ pCsr = (DbpageCursor *)sqlite3_malloc64(sizeof(DbpageCursor));
+ if( pCsr==0 ){
+ return SQLITE_NOMEM_BKPT;
+ }else{
+ memset(pCsr, 0, sizeof(DbpageCursor));
+ pCsr->base.pVtab = pVTab;
+ pCsr->pgno = -1;
+ }
+
+ *ppCursor = (sqlite3_vtab_cursor *)pCsr;
+ return SQLITE_OK;
+}
+
+/*
+** Close a dbpagevfs cursor.
+*/
+static int dbpageClose(sqlite3_vtab_cursor *pCursor){
+ DbpageCursor *pCsr = (DbpageCursor *)pCursor;
+ sqlite3_free(pCsr);
+ return SQLITE_OK;
+}
+
+/*
+** Move a dbpagevfs cursor to the next entry in the file.
+*/
+static int dbpageNext(sqlite3_vtab_cursor *pCursor){
+ int rc = SQLITE_OK;
+ DbpageCursor *pCsr = (DbpageCursor *)pCursor;
+ pCsr->pgno++;
+ return rc;
+}
+
+static int dbpageEof(sqlite3_vtab_cursor *pCursor){
+ DbpageCursor *pCsr = (DbpageCursor *)pCursor;
+ return pCsr->pgno > pCsr->mxPgno;
+}
+
+static int dbpageFilter(
+ sqlite3_vtab_cursor *pCursor,
+ int idxNum, const char *idxStr,
+ int argc, sqlite3_value **argv
+){
+ DbpageCursor *pCsr = (DbpageCursor *)pCursor;
+ DbpageTable *pTab = (DbpageTable *)pCursor->pVtab;
+ int rc = SQLITE_OK;
+ Btree *pBt = pTab->db->aDb[pTab->iDb].pBt;
+
+ pTab->szPage = sqlite3BtreeGetPageSize(pBt);
+ pTab->nPage = sqlite3BtreeLastPage(pBt);
+ if( idxNum==1 ){
+ pCsr->pgno = sqlite3_value_int(argv[0]);
+ if( pCsr->pgno<1 || pCsr->pgno>pTab->nPage ){
+ pCsr->pgno = 1;
+ pCsr->mxPgno = 0;
+ }else{
+ pCsr->mxPgno = pCsr->pgno;
+ }
+ }else{
+ pCsr->pgno = 1;
+ pCsr->mxPgno = pTab->nPage;
+ }
+ return rc;
+}
+
+static int dbpageColumn(
+ sqlite3_vtab_cursor *pCursor,
+ sqlite3_context *ctx,
+ int i
+){
+ DbpageCursor *pCsr = (DbpageCursor *)pCursor;
+ DbpageTable *pTab = (DbpageTable *)pCursor->pVtab;
+ int rc = SQLITE_OK;
+ switch( i ){
+ case 0: { /* pgno */
+ sqlite3_result_int(ctx, pCsr->pgno);
+ break;
+ }
+ case 1: { /* data */
+ DbPage *pDbPage = 0;
+ rc = sqlite3PagerGet(pTab->pPager, pCsr->pgno, (DbPage**)&pDbPage, 0);
+ if( rc==SQLITE_OK ){
+ sqlite3_result_blob(ctx, sqlite3PagerGetData(pDbPage), pTab->szPage,
+ SQLITE_TRANSIENT);
+ }
+ sqlite3PagerUnref(pDbPage);
+ break;
+ }
+ default: { /* schema */
+ sqlite3 *db = sqlite3_context_db_handle(ctx);
+ sqlite3_result_text(ctx, db->aDb[pTab->iDb].zDbSName, -1, SQLITE_STATIC);
+ break;
+ }
+ }
+ return SQLITE_OK;
+}
+
+static int dbpageRowid(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
+ DbpageCursor *pCsr = (DbpageCursor *)pCursor;
+ *pRowid = pCsr->pgno;
+ return SQLITE_OK;
+}
+
+static int dbpageUpdate(
+ sqlite3_vtab *pVtab,
+ int argc,
+ sqlite3_value **argv,
+ sqlite_int64 *pRowid
+){
+ DbpageTable *pTab = (DbpageTable *)pVtab;
+ int pgno;
+ DbPage *pDbPage = 0;
+ int rc = SQLITE_OK;
+ char *zErr = 0;
+
+ if( argc==1 ){
+ zErr = "cannot delete";
+ goto update_fail;
+ }
+ pgno = sqlite3_value_int(argv[0]);
+ if( pgno<1 || pgno>pTab->nPage ){
+ zErr = "bad page number";
+ goto update_fail;
+ }
+ if( sqlite3_value_int(argv[1])!=pgno ){
+ zErr = "cannot insert";
+ goto update_fail;
+ }
+ if( sqlite3_value_type(argv[3])!=SQLITE_BLOB
+ || sqlite3_value_bytes(argv[3])!=pTab->szPage
+ ){
+ zErr = "bad page value";
+ goto update_fail;
+ }
+ rc = sqlite3PagerGet(pTab->pPager, pgno, (DbPage**)&pDbPage, 0);
+ if( rc==SQLITE_OK ){
+ rc = sqlite3PagerWrite(pDbPage);
+ if( rc==SQLITE_OK ){
+ memcpy(sqlite3PagerGetData(pDbPage),
+ sqlite3_value_blob(argv[3]),
+ pTab->szPage);
+ }
+ }
+ sqlite3PagerUnref(pDbPage);
+ return rc;
+
+update_fail:
+ sqlite3_free(pVtab->zErrMsg);
+ pVtab->zErrMsg = sqlite3_mprintf("%s", zErr);
+ return SQLITE_ERROR;
+}
+
+/*
+** Invoke this routine to register the "dbpage" virtual table module
+*/
+int sqlite3DbpageRegister(sqlite3 *db){
+ static sqlite3_module dbpage_module = {
+ 0, /* iVersion */
+ dbpageConnect, /* xCreate */
+ dbpageConnect, /* xConnect */
+ dbpageBestIndex, /* xBestIndex */
+ dbpageDisconnect, /* xDisconnect */
+ dbpageDisconnect, /* xDestroy */
+ dbpageOpen, /* xOpen - open a cursor */
+ dbpageClose, /* xClose - close a cursor */
+ dbpageFilter, /* xFilter - configure scan constraints */
+ dbpageNext, /* xNext - advance a cursor */
+ dbpageEof, /* xEof - check for end of scan */
+ dbpageColumn, /* xColumn - read data */
+ dbpageRowid, /* xRowid - read data */
+ dbpageUpdate, /* xUpdate */
+ 0, /* xBegin */
+ 0, /* xSync */
+ 0, /* xCommit */
+ 0, /* xRollback */
+ 0, /* xFindMethod */
+ 0, /* xRename */
+ 0, /* xSavepoint */
+ 0, /* xRelease */
+ 0, /* xRollbackTo */
+ };
+ return sqlite3_create_module(db, "sqlite_dbpage", &dbpage_module, 0);
+}
+#elif defined(SQLITE_ENABLE_DBPAGE_VTAB)
+int sqlite3DbpageRegister(sqlite3 *db){ return SQLITE_OK; }
+#endif /* SQLITE_ENABLE_DBSTAT_VTAB */
diff --git a/src/main.c b/src/main.c
index 3d7609ce5..49613f6c7 100644
--- a/src/main.c
+++ b/src/main.c
@@ -3054,6 +3054,12 @@ static int openDatabase(
}
#endif
+#ifdef SQLITE_ENABLE_DBPAGE_VTAB
+ if( !db->mallocFailed && rc==SQLITE_OK){
+ rc = sqlite3DbpageRegister(db);
+ }
+#endif
+
#ifdef SQLITE_ENABLE_DBSTAT_VTAB
if( !db->mallocFailed && rc==SQLITE_OK){
rc = sqlite3DbstatRegister(db);
diff --git a/src/shell.c.in b/src/shell.c.in
index 896d475ed..b62c05507 100644
--- a/src/shell.c.in
+++ b/src/shell.c.in
@@ -3611,20 +3611,24 @@ static int shell_dbinfo_command(ShellState *p, int nArg, char **azArg){
{ "schema size:",
"SELECT total(length(sql)) FROM %s" },
};
- sqlite3_file *pFile = 0;
int i;
char *zSchemaTab;
char *zDb = nArg>=2 ? azArg[1] : "main";
+ sqlite3_stmt *pStmt = 0;
unsigned char aHdr[100];
open_db(p, 0);
if( p->db==0 ) return 1;
- sqlite3_file_control(p->db, zDb, SQLITE_FCNTL_FILE_POINTER, &pFile);
- if( pFile==0 || pFile->pMethods==0 || pFile->pMethods->xRead==0 ){
- return 1;
- }
- i = pFile->pMethods->xRead(pFile, aHdr, 100, 0);
- if( i!=SQLITE_OK ){
+ sqlite3_prepare_v2(p->db,"SELECT data FROM sqlite_dbpage(?1) WHERE pgno=1",
+ -1, &pStmt, 0);
+ sqlite3_bind_text(pStmt, 1, zDb, -1, SQLITE_STATIC);
+ if( sqlite3_step(pStmt)==SQLITE_ROW
+ && sqlite3_column_bytes(pStmt,0)>100
+ ){
+ memcpy(aHdr, sqlite3_column_blob(pStmt,0), 100);
+ sqlite3_finalize(pStmt);
+ }else{
raw_printf(stderr, "unable to read database header\n");
+ sqlite3_finalize(pStmt);
return 1;
}
i = get2byteInt(aHdr+16);
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index a8f1bed51..0cc435d7b 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -4400,6 +4400,9 @@ int sqlite3ThreadCreate(SQLiteThread**,void*(*)(void*),void*);
int sqlite3ThreadJoin(SQLiteThread*, void**);
#endif
+#if defined(SQLITE_ENABLE_DBPAGE_VTAB) || defined(SQLITE_TEST)
+int sqlite3DbpageRegister(sqlite3*);
+#endif
#if defined(SQLITE_ENABLE_DBSTAT_VTAB) || defined(SQLITE_TEST)
int sqlite3DbstatRegister(sqlite3*);
#endif
generated by cgit v1.2.3 (git 2.25.1) at 2025-07-18 19:00:32 +0000