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Comment:Prevent a NULL-pointer dereference when trying to parse a illegal schema entry that contains a window function while doing a RENAME COLUMN. Forum post ec2a2e0deb.
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SHA3-256: 58de3c2b1a773a71b2d6a5d9a4dc0f839185d78d64519e7d267ad133b9830120
User & Date: drh 2022-03-10 16:26:00
Context
2022-03-10
19:44
Amend sqlite3_column_*() doc table. (no code change) (check-in: 1f473099 user: larrybr tags: trunk)
16:28
Prevent a NULL-pointer dereference when trying to parse a illegal schema entry that contains a window function while doing a RENAME COLUMN. Forum post ec2a2e0deb. (check-in: 2c393228 user: drh tags: branch-3.38)
16:26
Prevent a NULL-pointer dereference when trying to parse a illegal schema entry that contains a window function while doing a RENAME COLUMN. Forum post ec2a2e0deb. (check-in: 58de3c2b user: drh tags: trunk)
16:01
Refactor Window.pFunc into Window.pWFunc to disambiguate from other uses of the variable or field named "pFunc". (check-in: d9475ebc user: drh tags: trunk)
Changes
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Changes to src/window.c.

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** any SQL window functions, this function is a no-op. Otherwise, it 
** rewrites the SELECT statement so that window function xStep functions
** are invoked in the correct order as described under "SELECT REWRITING"
** at the top of this file.
*/
int sqlite3WindowRewrite(Parse *pParse, Select *p){
  int rc = SQLITE_OK;


  if( p->pWin && p->pPrior==0 && ALWAYS((p->selFlags & SF_WinRewrite)==0) ){


    Vdbe *v = sqlite3GetVdbe(pParse);
    sqlite3 *db = pParse->db;
    Select *pSub = 0;             /* The subquery */
    SrcList *pSrc = p->pSrc;
    Expr *pWhere = p->pWhere;
    ExprList *pGroupBy = p->pGroupBy;
    Expr *pHaving = p->pHaving;








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** any SQL window functions, this function is a no-op. Otherwise, it 
** rewrites the SELECT statement so that window function xStep functions
** are invoked in the correct order as described under "SELECT REWRITING"
** at the top of this file.
*/
int sqlite3WindowRewrite(Parse *pParse, Select *p){
  int rc = SQLITE_OK;
  if( p->pWin
   && p->pPrior==0
   && ALWAYS((p->selFlags & SF_WinRewrite)==0)
   && !IN_RENAME_OBJECT
  ){
    Vdbe *v = sqlite3GetVdbe(pParse);
    sqlite3 *db = pParse->db;
    Select *pSub = 0;             /* The subquery */
    SrcList *pSrc = p->pSrc;
    Expr *pWhere = p->pWhere;
    ExprList *pGroupBy = p->pGroupBy;
    Expr *pHaving = p->pHaving;
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    /* Append the arguments passed to each window function to the
    ** sub-select expression list. Also allocate two registers for each
    ** window function - one for the accumulator, another for interim
    ** results.  */
    for(pWin=pMWin; pWin; pWin=pWin->pNextWin){
      ExprList *pArgs;
      assert( ExprUseXList(pWin->pOwner) );

      pArgs = pWin->pOwner->x.pList;
      if( pWin->pWFunc->funcFlags & SQLITE_FUNC_SUBTYPE ){
        selectWindowRewriteEList(pParse, pMWin, pSrc, pArgs, pTab, &pSublist);
        pWin->iArgCol = (pSublist ? pSublist->nExpr : 0);
        pWin->bExprArgs = 1;
      }else{
        pWin->iArgCol = (pSublist ? pSublist->nExpr : 0);








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    /* Append the arguments passed to each window function to the
    ** sub-select expression list. Also allocate two registers for each
    ** window function - one for the accumulator, another for interim
    ** results.  */
    for(pWin=pMWin; pWin; pWin=pWin->pNextWin){
      ExprList *pArgs;
      assert( ExprUseXList(pWin->pOwner) );
      assert( pWin->pWFunc!=0 );
      pArgs = pWin->pOwner->x.pList;
      if( pWin->pWFunc->funcFlags & SQLITE_FUNC_SUBTYPE ){
        selectWindowRewriteEList(pParse, pMWin, pSrc, pArgs, pTab, &pSublist);
        pWin->iArgCol = (pSublist ? pSublist->nExpr : 0);
        pWin->bExprArgs = 1;
      }else{
        pWin->iArgCol = (pSublist ? pSublist->nExpr : 0);
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