diff options
Diffstat (limited to 'src/vdbevtab.c')
| -rw-r--r-- | src/vdbevtab.c | 424 |
1 files changed, 424 insertions, 0 deletions
diff --git a/src/vdbevtab.c b/src/vdbevtab.c new file mode 100644 index 0000000..e9bafd4 --- /dev/null +++ b/src/vdbevtab.c @@ -0,0 +1,424 @@ +/* +** 2020-03-23 +** +** 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 implements virtual-tables for examining the bytecode content +** of a prepared statement. +*/ +#include "sqliteInt.h" +#if defined(SQLITE_ENABLE_BYTECODE_VTAB) && !defined(SQLITE_OMIT_VIRTUALTABLE) +#include "vdbeInt.h" + +/* An instance of the bytecode() table-valued function. +*/ +typedef struct bytecodevtab bytecodevtab; +struct bytecodevtab { + sqlite3_vtab base; /* Base class - must be first */ + sqlite3 *db; /* Database connection */ + int bTablesUsed; /* 2 for tables_used(). 0 for bytecode(). */ +}; + +/* A cursor for scanning through the bytecode +*/ +typedef struct bytecodevtab_cursor bytecodevtab_cursor; +struct bytecodevtab_cursor { + sqlite3_vtab_cursor base; /* Base class - must be first */ + sqlite3_stmt *pStmt; /* The statement whose bytecode is displayed */ + int iRowid; /* The rowid of the output table */ + int iAddr; /* Address */ + int needFinalize; /* Cursors owns pStmt and must finalize it */ + int showSubprograms; /* Provide a listing of subprograms */ + Op *aOp; /* Operand array */ + char *zP4; /* Rendered P4 value */ + const char *zType; /* tables_used.type */ + const char *zSchema; /* tables_used.schema */ + const char *zName; /* tables_used.name */ + Mem sub; /* Subprograms */ +}; + +/* +** Create a new bytecode() table-valued function. +*/ +static int bytecodevtabConnect( + sqlite3 *db, + void *pAux, + int argc, const char *const*argv, + sqlite3_vtab **ppVtab, + char **pzErr +){ + bytecodevtab *pNew; + int rc; + int isTabUsed = pAux!=0; + const char *azSchema[2] = { + /* bytecode() schema */ + "CREATE TABLE x(" + "addr INT," + "opcode TEXT," + "p1 INT," + "p2 INT," + "p3 INT," + "p4 TEXT," + "p5 INT," + "comment TEXT," + "subprog TEXT," + "stmt HIDDEN" + ");", + + /* Tables_used() schema */ + "CREATE TABLE x(" + "type TEXT," + "schema TEXT," + "name TEXT," + "wr INT," + "subprog TEXT," + "stmt HIDDEN" + ");" + }; + + rc = sqlite3_declare_vtab(db, azSchema[isTabUsed]); + if( rc==SQLITE_OK ){ + pNew = sqlite3_malloc( sizeof(*pNew) ); + *ppVtab = (sqlite3_vtab*)pNew; + if( pNew==0 ) return SQLITE_NOMEM; + memset(pNew, 0, sizeof(*pNew)); + pNew->db = db; + pNew->bTablesUsed = isTabUsed*2; + } + return rc; +} + +/* +** This method is the destructor for bytecodevtab objects. +*/ +static int bytecodevtabDisconnect(sqlite3_vtab *pVtab){ + bytecodevtab *p = (bytecodevtab*)pVtab; + sqlite3_free(p); + return SQLITE_OK; +} + +/* +** Constructor for a new bytecodevtab_cursor object. +*/ +static int bytecodevtabOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){ + bytecodevtab *pVTab = (bytecodevtab*)p; + bytecodevtab_cursor *pCur; + pCur = sqlite3_malloc( sizeof(*pCur) ); + if( pCur==0 ) return SQLITE_NOMEM; + memset(pCur, 0, sizeof(*pCur)); + sqlite3VdbeMemInit(&pCur->sub, pVTab->db, 1); + *ppCursor = &pCur->base; + return SQLITE_OK; +} + +/* +** Clear all internal content from a bytecodevtab cursor. +*/ +static void bytecodevtabCursorClear(bytecodevtab_cursor *pCur){ + sqlite3_free(pCur->zP4); + pCur->zP4 = 0; + sqlite3VdbeMemRelease(&pCur->sub); + sqlite3VdbeMemSetNull(&pCur->sub); + if( pCur->needFinalize ){ + sqlite3_finalize(pCur->pStmt); + } + pCur->pStmt = 0; + pCur->needFinalize = 0; + pCur->zType = 0; + pCur->zSchema = 0; + pCur->zName = 0; +} + +/* +** Destructor for a bytecodevtab_cursor. +*/ +static int bytecodevtabClose(sqlite3_vtab_cursor *cur){ + bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur; + bytecodevtabCursorClear(pCur); + sqlite3_free(pCur); + return SQLITE_OK; +} + + +/* +** Advance a bytecodevtab_cursor to its next row of output. +*/ +static int bytecodevtabNext(sqlite3_vtab_cursor *cur){ + bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur; + bytecodevtab *pTab = (bytecodevtab*)cur->pVtab; + int rc; + if( pCur->zP4 ){ + sqlite3_free(pCur->zP4); + pCur->zP4 = 0; + } + if( pCur->zName ){ + pCur->zName = 0; + pCur->zType = 0; + pCur->zSchema = 0; + } + rc = sqlite3VdbeNextOpcode( + (Vdbe*)pCur->pStmt, + pCur->showSubprograms ? &pCur->sub : 0, + pTab->bTablesUsed, + &pCur->iRowid, + &pCur->iAddr, + &pCur->aOp); + if( rc!=SQLITE_OK ){ + sqlite3VdbeMemSetNull(&pCur->sub); + pCur->aOp = 0; + } + return SQLITE_OK; +} + +/* +** Return TRUE if the cursor has been moved off of the last +** row of output. +*/ +static int bytecodevtabEof(sqlite3_vtab_cursor *cur){ + bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur; + return pCur->aOp==0; +} + +/* +** Return values of columns for the row at which the bytecodevtab_cursor +** is currently pointing. +*/ +static int bytecodevtabColumn( + sqlite3_vtab_cursor *cur, /* The cursor */ + sqlite3_context *ctx, /* First argument to sqlite3_result_...() */ + int i /* Which column to return */ +){ + bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur; + bytecodevtab *pVTab = (bytecodevtab*)cur->pVtab; + Op *pOp = pCur->aOp + pCur->iAddr; + if( pVTab->bTablesUsed ){ + if( i==4 ){ + i = 8; + }else{ + if( i<=2 && pCur->zType==0 ){ + Schema *pSchema; + HashElem *k; + int iDb = pOp->p3; + Pgno iRoot = (Pgno)pOp->p2; + sqlite3 *db = pVTab->db; + pSchema = db->aDb[iDb].pSchema; + pCur->zSchema = db->aDb[iDb].zDbSName; + for(k=sqliteHashFirst(&pSchema->tblHash); k; k=sqliteHashNext(k)){ + Table *pTab = (Table*)sqliteHashData(k); + if( !IsVirtual(pTab) && pTab->tnum==iRoot ){ + pCur->zName = pTab->zName; + pCur->zType = "table"; + break; + } + } + if( pCur->zName==0 ){ + for(k=sqliteHashFirst(&pSchema->idxHash); k; k=sqliteHashNext(k)){ + Index *pIdx = (Index*)sqliteHashData(k); + if( pIdx->tnum==iRoot ){ + pCur->zName = pIdx->zName; + pCur->zType = "index"; + } + } + } + } + i += 10; + } + } + switch( i ){ + case 0: /* addr */ + sqlite3_result_int(ctx, pCur->iAddr); + break; + case 1: /* opcode */ + sqlite3_result_text(ctx, (char*)sqlite3OpcodeName(pOp->opcode), + -1, SQLITE_STATIC); + break; + case 2: /* p1 */ + sqlite3_result_int(ctx, pOp->p1); + break; + case 3: /* p2 */ + sqlite3_result_int(ctx, pOp->p2); + break; + case 4: /* p3 */ + sqlite3_result_int(ctx, pOp->p3); + break; + case 5: /* p4 */ + case 7: /* comment */ + if( pCur->zP4==0 ){ + pCur->zP4 = sqlite3VdbeDisplayP4(pVTab->db, pOp); + } + if( i==5 ){ + sqlite3_result_text(ctx, pCur->zP4, -1, SQLITE_STATIC); + }else{ +#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS + char *zCom = sqlite3VdbeDisplayComment(pVTab->db, pOp, pCur->zP4); + sqlite3_result_text(ctx, zCom, -1, sqlite3_free); +#endif + } + break; + case 6: /* p5 */ + sqlite3_result_int(ctx, pOp->p5); + break; + case 8: { /* subprog */ + Op *aOp = pCur->aOp; + assert( aOp[0].opcode==OP_Init ); + assert( aOp[0].p4.z==0 || strncmp(aOp[0].p4.z,"-" "- ",3)==0 ); + if( pCur->iRowid==pCur->iAddr+1 ){ + break; /* Result is NULL for the main program */ + }else if( aOp[0].p4.z!=0 ){ + sqlite3_result_text(ctx, aOp[0].p4.z+3, -1, SQLITE_STATIC); + }else{ + sqlite3_result_text(ctx, "(FK)", 4, SQLITE_STATIC); + } + break; + } + case 10: /* tables_used.type */ + sqlite3_result_text(ctx, pCur->zType, -1, SQLITE_STATIC); + break; + case 11: /* tables_used.schema */ + sqlite3_result_text(ctx, pCur->zSchema, -1, SQLITE_STATIC); + break; + case 12: /* tables_used.name */ + sqlite3_result_text(ctx, pCur->zName, -1, SQLITE_STATIC); + break; + case 13: /* tables_used.wr */ + sqlite3_result_int(ctx, pOp->opcode==OP_OpenWrite); + break; + } + return SQLITE_OK; +} + +/* +** Return the rowid for the current row. In this implementation, the +** rowid is the same as the output value. +*/ +static int bytecodevtabRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){ + bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur; + *pRowid = pCur->iRowid; + return SQLITE_OK; +} + +/* +** Initialize a cursor. +** +** idxNum==0 means show all subprograms +** idxNum==1 means show only the main bytecode and omit subprograms. +*/ +static int bytecodevtabFilter( + sqlite3_vtab_cursor *pVtabCursor, + int idxNum, const char *idxStr, + int argc, sqlite3_value **argv +){ + bytecodevtab_cursor *pCur = (bytecodevtab_cursor *)pVtabCursor; + bytecodevtab *pVTab = (bytecodevtab *)pVtabCursor->pVtab; + int rc = SQLITE_OK; + + bytecodevtabCursorClear(pCur); + pCur->iRowid = 0; + pCur->iAddr = 0; + pCur->showSubprograms = idxNum==0; + assert( argc==1 ); + if( sqlite3_value_type(argv[0])==SQLITE_TEXT ){ + const char *zSql = (const char*)sqlite3_value_text(argv[0]); + if( zSql==0 ){ + rc = SQLITE_NOMEM; + }else{ + rc = sqlite3_prepare_v2(pVTab->db, zSql, -1, &pCur->pStmt, 0); + pCur->needFinalize = 1; + } + }else{ + pCur->pStmt = (sqlite3_stmt*)sqlite3_value_pointer(argv[0],"stmt-pointer"); + } + if( pCur->pStmt==0 ){ + pVTab->base.zErrMsg = sqlite3_mprintf( + "argument to %s() is not a valid SQL statement", + pVTab->bTablesUsed ? "tables_used" : "bytecode" + ); + rc = SQLITE_ERROR; + }else{ + bytecodevtabNext(pVtabCursor); + } + return rc; +} + +/* +** We must have a single stmt=? constraint that will be passed through +** into the xFilter method. If there is no valid stmt=? constraint, +** then return an SQLITE_CONSTRAINT error. +*/ +static int bytecodevtabBestIndex( + sqlite3_vtab *tab, + sqlite3_index_info *pIdxInfo +){ + int i; + int rc = SQLITE_CONSTRAINT; + struct sqlite3_index_constraint *p; + bytecodevtab *pVTab = (bytecodevtab*)tab; + int iBaseCol = pVTab->bTablesUsed ? 4 : 8; + pIdxInfo->estimatedCost = (double)100; + pIdxInfo->estimatedRows = 100; + pIdxInfo->idxNum = 0; + for(i=0, p=pIdxInfo->aConstraint; i<pIdxInfo->nConstraint; i++, p++){ + if( p->usable==0 ) continue; + if( p->op==SQLITE_INDEX_CONSTRAINT_EQ && p->iColumn==iBaseCol+1 ){ + rc = SQLITE_OK; + pIdxInfo->aConstraintUsage[i].omit = 1; + pIdxInfo->aConstraintUsage[i].argvIndex = 1; + } + if( p->op==SQLITE_INDEX_CONSTRAINT_ISNULL && p->iColumn==iBaseCol ){ + pIdxInfo->aConstraintUsage[i].omit = 1; + pIdxInfo->idxNum = 1; + } + } + return rc; +} + +/* +** This following structure defines all the methods for the +** virtual table. +*/ +static sqlite3_module bytecodevtabModule = { + /* iVersion */ 0, + /* xCreate */ 0, + /* xConnect */ bytecodevtabConnect, + /* xBestIndex */ bytecodevtabBestIndex, + /* xDisconnect */ bytecodevtabDisconnect, + /* xDestroy */ 0, + /* xOpen */ bytecodevtabOpen, + /* xClose */ bytecodevtabClose, + /* xFilter */ bytecodevtabFilter, + /* xNext */ bytecodevtabNext, + /* xEof */ bytecodevtabEof, + /* xColumn */ bytecodevtabColumn, + /* xRowid */ bytecodevtabRowid, + /* xUpdate */ 0, + /* xBegin */ 0, + /* xSync */ 0, + /* xCommit */ 0, + /* xRollback */ 0, + /* xFindMethod */ 0, + /* xRename */ 0, + /* xSavepoint */ 0, + /* xRelease */ 0, + /* xRollbackTo */ 0, + /* xShadowName */ 0 +}; + + +int sqlite3VdbeBytecodeVtabInit(sqlite3 *db){ + int rc; + rc = sqlite3_create_module(db, "bytecode", &bytecodevtabModule, 0); + if( rc==SQLITE_OK ){ + rc = sqlite3_create_module(db, "tables_used", &bytecodevtabModule, &db); + } + return rc; +} +#elif defined(SQLITE_ENABLE_BYTECODE_VTAB) +int sqlite3VdbeBytecodeVtabInit(sqlite3 *db){ return SQLITE_OK; } +#endif /* SQLITE_ENABLE_BYTECODE_VTAB */ |