SQLite

#include "sqlite3.h"

typedef struct sqlite3_session sqlite3_session;
typedef struct sqlite3_changeset_iter sqlite3_changeset_iter;

/*
** Create a new session object attached to database handle db. If successful,
** a pointer to the new object is written to *ppSession and SQLITE_OK is
** returned. If an error occurs, *ppSession is set to NULL and an SQLite
** error code (e.g. [SQLITE_NOMEM]) is returned.
**
** It is possible to create multiple session objects attached to a single
** database handle.
**
** Session objects created using this function should be deleted using the
** [sqlite3session_delete()] function before the database handle that they
** are attached to is itself closed. If the database handle is closed before
** the session object is deleted, then the results of calling any session
** module function, including [sqlite3session_delete()] on the session object
** are undefined.
**
** Because the session module uses the [sqlite3_preupdate_hook()] API, it
** is not possible for an application to register a pre-update hook on a
** database handle that has one or more session objects attached. Nor is
** it possible to create a session object attached to a database handle for
** which a pre-update hook is already defined. The results of attempting 
** either of these things are undefined.
**
** The session object will be used to create changesets for tables in
** database zDb, where zDb is either "main", or "temp", or the name of an
** attached database. It is not an error if database zDb does not exist
** to the database when the session object is created.
*/
int sqlite3session_create(
  sqlite3 *db,                    /* Database handle */
  const char *zDb,                /* Name of db (e.g. "main") */
  sqlite3_session **ppSession     /* OUT: New session object */
);

/*
** Delete a session object previously allocated using 
** [sqlite3session_create()]. Once a session object has been deleted, the
** results of attempting to use pSession with any other session module
** function are undefined.
**
** Session objects must be deleted before the database handle to which they
** are attached is closed. Refer to the documentation for 
** [sqlite3session_create()] for details.
*/
void sqlite3session_delete(sqlite3_session *pSession);

/*
** Enable or disable the recording of changes by a session object. When
** enabled, a session object records changes made to the database. When
** disabled - it does not. A newly created session object is enabled.
**
** Passing zero to this function disables the session. Passing a value
** greater than zero enables it. Passing a value less than zero is a 

*/
int sqlite3session_attach(
  sqlite3_session *pSession,      /* Session object */
  const char *zTab                /* Table name */
);

/*
** Obtain a changeset containing changes to the tables attached to the 
** session object passed as the first argument. If successful, 
** set *ppChangeset to point to a buffer containing the changeset 
** and *pnChangeset to the size of the changeset in bytes before returning
** SQLITE_OK. If an error occurs, set both *ppChangeset and *pnChangeset to
** zero and return an SQLite error code.
**
** Following a successful call to this function, it is the responsibility of
** the caller to eventually free the buffer that *ppChangeset points to using
** [sqlite3_free()].
*/
int sqlite3session_changeset(
  sqlite3_session *pSession,      /* Session object */
  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
  void **ppChangeset              /* OUT: Buffer containing changeset */
);






/*
** Create an iterator used to iterate through the contents of a changeset.
*/
int sqlite3changeset_start(
  sqlite3_changeset_iter **ppIter,
  int nChangeset, 
  void *pChangeset

    char const *zName,            /* Table name */
    sqlite3_int64 iKey1,          /* Rowid of row about to be deleted/updated */
    sqlite3_int64 iKey2           /* New rowid value (for a rowid UPDATE) */
  ),
  void*
);
SQLITE_EXPERIMENTAL int sqlite3_preupdate_old(sqlite3 *, int, sqlite3_value **);
SQLITE_EXPERIMENTAL int sqlite3_preupdate_count(sqlite3 *);
SQLITE_EXPERIMENTAL int sqlite3_preupdate_new(sqlite3 *, int, sqlite3_value **);

/*
** Undo the hack that converts floating point types to integer for
** builds on processors without floating point support.
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# undef double

      }
    }
#endif
    break;
  }

  case DB_PREUPDATE: {
    static const char *azSub[] = {"count", "hook", "new", "old", 0};
    enum DbPreupdateSubCmd {
      PRE_COUNT, PRE_HOOK, PRE_NEW, PRE_OLD
    };
    int iSub;

    if( objc<3 ){
      Tcl_WrongNumArgs(interp, 2, objv, "SUB-COMMAND ?ARGS?");
    }
    if( Tcl_GetIndexFromObj(interp, objv[2], azSub, "sub-command", 0, &iSub) ){

          Tcl_WrongNumArgs(interp, 2, objv, "hook ?SCRIPT?");
          return TCL_ERROR;
        }
        DbHookCmd(interp, pDb, (objc==4 ? objv[3] : 0), &pDb->pPreUpdateHook);
        break;
      }

      case PRE_NEW:
      case PRE_OLD: {
        int iIdx;
        sqlite3_value *pValue;
        if( objc!=4 ){
          Tcl_WrongNumArgs(interp, 3, objv, "INDEX");
          return TCL_ERROR;
        }
        if( Tcl_GetIntFromObj(interp, objv[3], &iIdx) ){
          return TCL_ERROR;
        }

        if( iSub==PRE_OLD ){

          rc = sqlite3_preupdate_old(pDb->db, iIdx, &pValue);

        }else{

          assert( iSub==PRE_NEW );
          rc = sqlite3_preupdate_new(pDb->db, iIdx, &pValue);
        }

        if( rc==SQLITE_OK ){
          Tcl_Obj *pObj = Tcl_NewStringObj(sqlite3_value_text(pValue), -1);
          Tcl_SetObjResult(interp, pObj);
        }else{



          Tcl_AppendResult(interp, sqlite3_errmsg(pDb->db), 0);
          return TCL_ERROR;
        }
      }
    }

    break;

    /* Delete the index entries associated with the current record.  */
    j1 = sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, regOldRowid);
    sqlite3GenerateRowIndexDelete(pParse, pTab, iCur, aRegIdx);
  
    /* If changing the rowid value, or if there are foreign key constraints
    ** to process, delete the old record. Otherwise, add a noop OP_Delete
    ** to invoke the pre-update hook.
    **
    ** That (regNew==regnewRowid+1) is true is also important for the 
    ** pre-update hook. If hte caller invokes preupdate_new(), the returned
    ** value is copied from memory cell (regNewRowid+1+iCol), where iCol
    ** is the column index supplied by the user.
    */
    assert( regNew==regNewRowid+1 );
    sqlite3VdbeAddOp3(v, OP_Delete, iCur,
        OPFLAG_ISUPDATE | ((hasFK || chngRowid) ? 0 : OPFLAG_ISNOOP),
        regNewRowid
    );
    if( !pParse->nested ){
      sqlite3VdbeChangeP4(v, -1, pTab->zName, P4_STATIC);
    }

  }

  /* Invoke the pre-update hook, if any */
  if( db->xPreUpdateCallback 
   && pOp->p4.z 
   && (!(pOp->p5 & OPFLAG_ISUPDATE) || pC->rowidIsValid==0)
  ){
    sqlite3VdbePreUpdateHook(p, pC, SQLITE_INSERT, zDb, zTbl, iKey, pOp->p2);


  }

  if( pOp->p5 & OPFLAG_NCHANGE ) p->nChange++;
  if( pOp->p5 & OPFLAG_LASTROWID ) db->lastRowid = iKey;
  if( pData->flags & MEM_Null ){
    pData->z = 0;
    pData->n = 0;

  /* Invoke the pre-update-hook if required. */
  if( db->xPreUpdateCallback && pOp->p4.z ){
    assert( !(opflags & OPFLAG_ISUPDATE) || (aMem[pOp->p3].flags & MEM_Int) );
    sqlite3VdbePreUpdateHook(p, pC,
        (opflags & OPFLAG_ISUPDATE) ? SQLITE_UPDATE : SQLITE_DELETE, 
        zDb, zTbl, iKey,
        pOp->p3
    );
  }

  if( opflags & OPFLAG_ISNOOP ) break;

  sqlite3BtreeSetCachedRowid(pC->pCursor, 0);
  rc = sqlite3BtreeDelete(pC->pCursor);

#define VDBE_MAGIC_DEAD     0xb606c3c8    /* The VDBE has been deallocated */

/*
** Structure used to store the context required by the 
** sqlite3_preupdate_*() API functions.
*/
struct PreUpdate {
  Vdbe *v;
  VdbeCursor *pCsr;               /* Cursor to read old values from */
  int op;                         /* One of SQLITE_INSERT, UPDATE, DELETE */
  u8 *aRecord;                    /* old.* database record */
  KeyInfo keyinfo;
  UnpackedRecord *pUnpacked;      /* Unpacked version of aRecord[] */
  UnpackedRecord *pNewUnpacked;   /* Unpacked version of new.* record */
  int iNewReg;                    /* Register for new.* values */
  Mem *aNew;                      /* Array of new.* values */
};

/*
** Function prototypes
*/
void sqlite3VdbeFreeCursor(Vdbe *, VdbeCursor*);
void sqliteVdbePopStack(Vdbe*,int);

const char *sqlite3OpcodeName(int);
int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve);
int sqlite3VdbeCloseStatement(Vdbe *, int);
void sqlite3VdbeFrameDelete(VdbeFrame*);
int sqlite3VdbeFrameRestore(VdbeFrame *);
void sqlite3VdbeMemStoreType(Mem *pMem);
void sqlite3VdbePreUpdateHook(
    Vdbe *, VdbeCursor *, int, const char*, const char*, i64, int);

#ifdef SQLITE_DEBUG
void sqlite3VdbeMemPrepareToChange(Vdbe*,Mem*);
#endif

#ifndef SQLITE_OMIT_FOREIGN_KEY
int sqlite3VdbeCheckFk(Vdbe *, int);

int sqlite3_stmt_status(sqlite3_stmt *pStmt, int op, int resetFlag){
  Vdbe *pVdbe = (Vdbe*)pStmt;
  int v = pVdbe->aCounter[op-1];
  if( resetFlag ) pVdbe->aCounter[op-1] = 0;
  return v;
}

/*
** This function is called from within a pre-update callback to retrieve
** a field of the row currently being updated or deleted.
*/
int sqlite3_preupdate_old(sqlite3 *db, int iIdx, sqlite3_value **ppValue){
  PreUpdate *p = db->pPreUpdate;
  int rc = SQLITE_OK;

  /* Test that this call is being made from within an SQLITE_DELETE or
  ** SQLITE_UPDATE pre-update callback, and that iIdx is within range. */
  if( !p || p->op==SQLITE_INSERT ){
    rc = SQLITE_MISUSE_BKPT;
    goto preupdate_old_out;
  }
  if( iIdx>=p->pCsr->nField || iIdx<0 ){
    rc = SQLITE_RANGE;
    goto preupdate_old_out;
  }

  /* If the old.* record has not yet been loaded into memory, do so now. */
  if( p->pUnpacked==0 ){
    u32 nRecord;
    u8 *aRecord;

    rc = sqlite3BtreeDataSize(p->pCsr->pCursor, &nRecord);
    if( rc!=SQLITE_OK ) goto preupdate_old_out;
    aRecord = sqlite3DbMallocRaw(db, nRecord);

  }

 preupdate_old_out:
  sqlite3Error(db, rc, 0);
  return sqlite3ApiExit(db, rc);
}

/*
** This function is called from within a pre-update callback to retrieve
** the number of columns in the row being updated, deleted or inserted.
*/
int sqlite3_preupdate_count(sqlite3 *db){
  PreUpdate *p = db->pPreUpdate;
  return (p ? p->pCsr->nField : 0);
}

/*
** This function is called from within a pre-update callback to retrieve
** a field of the row currently being updated or inserted.
*/
int sqlite3_preupdate_new(sqlite3 *db, int iIdx, sqlite3_value **ppValue){
  PreUpdate *p = db->pPreUpdate;
  int rc = SQLITE_OK;
  Mem *pMem;

  if( !p || p->op==SQLITE_DELETE ){
    rc = SQLITE_MISUSE_BKPT;
    goto preupdate_new_out;
  }
  if( iIdx>=p->pCsr->nField || iIdx<0 ){
    rc = SQLITE_RANGE;
    goto preupdate_new_out;
  }

  if( p->op==SQLITE_INSERT ){
    /* For an INSERT, memory cell p->iNewReg contains the serialized record
    ** that is being inserted. Deserialize it. */
    UnpackedRecord *pUnpack = p->pNewUnpacked;
    if( !pUnpack ){
      Mem *pData = &p->v->aMem[p->iNewReg];
      rc = sqlite3VdbeMemExpandBlob(pData);
      if( rc!=SQLITE_OK ) goto preupdate_new_out;
      pUnpack = sqlite3VdbeRecordUnpack(&p->keyinfo, pData->n, pData->z, 0, 0);
      if( !pUnpack ){
        rc = SQLITE_NOMEM;
        goto preupdate_new_out;
      }
      p->pNewUnpacked = pUnpack;
    }
    if( iIdx>=pUnpack->nField ){
      pMem = (sqlite3_value *)columnNullValue();
    }else{
      pMem = &pUnpack->aMem[iIdx];
      sqlite3VdbeMemStoreType(pMem);
    }
  }else{
    /* For an UPDATE, memory cell (p->iNewReg+1+iIdx) contains the required
    ** value. Make a copy of the cell contents and return a pointer to it.
    ** It is not safe to return a pointer to the memory cell itself as the
    ** caller may modify the value text encoding.
    */
    assert( p->op==SQLITE_UPDATE );
    if( !p->aNew ){
      p->aNew = (Mem *)sqlite3DbMallocZero(db, sizeof(Mem) * p->pCsr->nField);
      if( !p->aNew ){
        rc = SQLITE_NOMEM;
        goto preupdate_new_out;
      }
    }
    pMem = &p->aNew[iIdx];
    if( pMem->flags==0 ){
      rc = sqlite3VdbeMemCopy(pMem, &p->v->aMem[p->iNewReg+1+iIdx]);
      if( rc!=SQLITE_OK ) goto preupdate_new_out;
      sqlite3VdbeMemStoreType(pMem);
    }
  }
  *ppValue = pMem;

 preupdate_new_out:
  sqlite3Error(db, rc, 0);
  return sqlite3ApiExit(db, rc);
}

void sqlite3VdbePreUpdateHook(
  Vdbe *v,                        /* Vdbe pre-update hook is invoked by */
  VdbeCursor *pCsr,               /* Cursor to grab old.* values from */
  int op,                         /* SQLITE_INSERT, UPDATE or DELETE */
  const char *zDb,                /* Database name */
  const char *zTbl,               /* Table name */
  i64 iKey1,                      /* Initial key value */
  int iReg                        /* Register for new.* record */
){
  sqlite3 *db = v->db;
  i64 iKey2;

  PreUpdate preupdate;
  memset(&preupdate, 0, sizeof(PreUpdate));

  if( op==SQLITE_UPDATE ){
    iKey2 = v->aMem[iReg].u.i;
  }else{
    iKey2 = iKey1;
  }

  preupdate.v = v;
  preupdate.pCsr = pCsr;
  preupdate.op = op;
  preupdate.iNewReg = iReg;
  preupdate.keyinfo.db = db;
  preupdate.keyinfo.enc = ENC(db);
  preupdate.keyinfo.nField = pCsr->nField;
  db->pPreUpdate = &preupdate;
  db->xPreUpdateCallback(db->pPreUpdateArg, db, op, zDb, zTbl, iKey1, iKey2);
  db->pPreUpdate = 0;
  sqlite3DbFree(db, preupdate.aRecord);
  if( preupdate.pUnpacked ){
    sqlite3VdbeDeleteUnpackedRecord(preupdate.pUnpacked);
  }
  if( preupdate.pNewUnpacked ){
    sqlite3VdbeDeleteUnpackedRecord(preupdate.pNewUnpacked);
  }
  if( preupdate.aNew ){
    int i;
    for(i=0; i<pCsr->nField; i++){
      sqlite3VdbeMemRelease(&preupdate.aNew[i]);
    }
    sqlite3_free(preupdate.aNew);
  }
}

    set ::preupdate
  "] [list $X]
}

proc preupdate_hook {args} {
  set type [lindex $args 0]
  eval lappend ::preupdate $args
  if {$type != "INSERT"} {
    for {set i 0} {$i < [db preupdate count]} {incr i} {
      lappend ::preupdate [db preupdate old $i]
    }
  }
  if {$type != "DELETE"} {
    for {set i 0} {$i < [db preupdate count]} {incr i} {
      set rc [catch { db preupdate new $i } v]
      lappend ::preupdate $v
    }
  }
}

db close
forcedelete test.db
sqlite3 db test.db
db preupdate hook preupdate_hook

  INSERT INTO t3 VALUES(4, 16);
  INSERT INTO t3 VALUES(5, 25);
  INSERT INTO t3 VALUES(6, 36);
} 

do_preupdate_test 7.1.1 {
  INSERT INTO t1 VALUES('x', 'y')
} {INSERT main t1 1 1  x y}

# 7.1.2.1 does not use the xfer optimization. 7.1.2.2 does.
do_preupdate_test 7.1.2.1 {
  INSERT INTO t1 SELECT y, x FROM t2;
} {INSERT main t1 2 2 b a   INSERT main t1 3 3 d c}
do_preupdate_test 7.1.2.2 {
  INSERT INTO t1 SELECT * FROM t2;
} {INSERT main t1 4 4 a b   INSERT main t1 5 5 c d}

do_preupdate_test 7.1.3 {
  REPLACE INTO t1(rowid, a, b) VALUES(1, 1, 1);
} {
  DELETE main t1 1 1   x y
  INSERT main t1 1 1   1 1
}

do_preupdate_test 7.1.4 {
  REPLACE INTO t3 VALUES(4, NULL);
} {
  DELETE main t3 1 1   4 16
  INSERT main t3 4 4   4 {}
}

do_preupdate_test 7.1.5 {
  REPLACE INTO t3(rowid, i, j) VALUES(2, 6, NULL);
} {
  DELETE main t3 2 2  5 25
  DELETE main t3 3 3  6 36
  INSERT main t3 2 2  6 {}
}

do_execsql_test 7.2.0 { SELECT rowid FROM t1 } {1 2 3 4 5}

do_preupdate_test 7.2.1 {
  DELETE FROM t1 WHERE rowid = 3
} {

  INSERT INTO t3 VALUES(5, 25);
  INSERT INTO t3 VALUES(6, 36);
}

do_preupdate_test 7.3.1 {
  UPDATE t2 SET y = y||y;
} {
  UPDATE main t2 1 1   a b  a bb
  UPDATE main t2 2 2   c d  c dd
}

do_preupdate_test 7.3.2 {
  UPDATE t2 SET rowid = rowid-1;
} {
  UPDATE main t2 1 0   a bb  a bb
  UPDATE main t2 2 1   c dd  c dd
}

do_preupdate_test 7.3.3 {
  UPDATE OR REPLACE t2 SET rowid = 1 WHERE x = 'a'
} {
  DELETE main t2 1 1   c dd
  UPDATE main t2 0 1   a bb  a bb
}

do_preupdate_test 7.3.4.1 {
  UPDATE OR REPLACE t3 SET i = 5 WHERE i = 6
} {
  DELETE main t3 2 2   5 25
  UPDATE main t3 3 3   6 36  5 36
}

do_execsql_test 7.3.4.2 {
  INSERT INTO t3 VALUES(10, 100);
  SELECT rowid, * FROM t3;
} {1 4 16   3 5 36   4 10 100}

do_preupdate_test 7.3.5 {
  UPDATE OR REPLACE t3 SET rowid = 1, i = 5 WHERE j = 100;
} {
  DELETE main t3 1 1    4  16
  DELETE main t3 3 3    5  36
  UPDATE main t3 4 1   10 100  5 100
}

do_execsql_test 7.4.1.0 {
  CREATE TABLE t4(a, b);
  INSERT INTO t4 VALUES('a', 1);
  INSERT INTO t4 VALUES('b', 2);
  INSERT INTO t4 VALUES('c', 3);

    DELETE FROM t5 WHERE b = 1;
  END;
}
do_preupdate_test 7.4.2.1 {
  UPDATE t5 SET b = 4 WHERE a = 'c'
} {
  DELETE main t5 1 1   a 1
  UPDATE main t5 3 3   c 3  c 4
}

do_execsql_test 7.4.2.2 {
  INSERT INTO t5(rowid, a, b) VALUES(1, 'a', 1);
}

do_preupdate_test 7.4.2.3 {

} {
  DELETE main t7 1 1   one two {}
}

do_preupdate_test 7.5.1.2 {
  UPDATE t7 SET b = 'five'
} {
  UPDATE main t7 2 2   three four {}  three five {}
}

do_execsql_test 7.5.2.0 {
  CREATE TABLE t8(a, b);
  INSERT INTO t8 VALUES('one', 'two');
  INSERT INTO t8 VALUES('three', 'four');
  ALTER TABLE t8 ADD COLUMN c DEFAULT 'xxx';

  DELETE FROM t8 WHERE a = 'one'
} {
  DELETE main t8 1 1   one two xxx
}
do_preupdate_test 7.5.2.2 {
  UPDATE t8 SET b = 'five'
} {
  UPDATE main t8 2 2   three four xxx  three five xxx
}

finish_test