Fix Coverity issues reported in commit 25a30bbd423.

Fix several issues pointed out by Coverity (reported by Tome Lane).

- In row_is_in_frame(), return value of window_gettupleslot() was not
  checked.

- WinGetFuncArgInPartition() tried to derefference "isout" pointer
  even if it could be NULL in some places.

Besides the issues, I also fixed a compiler warning reported by Álvaro
Herrera.

Moreover, in WinGetFuncArgInPartition refactor the do...while loop so
that the codes inside the loop simpler. Also simplify the case when
abs_pos < 0.

Author: Tatsuo Ishii <ishii@postgresql.org>
Reviewed-by: Paul Ramsey <pramsey@cleverelephant.ca>
Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Reported-by: Álvaro Herrera <alvherre@kurilemu.de>
Discussion: https://postgr.es/m/1686755.1759679957%40sss.pgh.pa.us
Discussion: https://postgr.es/m/202510051612.gw67jlc2iqpw%40alvherre.pgsql

diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index cf667c81211402230969c8cc221e9581f0626201..0698aae37a7e4033f41699dfde43833c231741ce 100644 (file)
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -1501,8 +1501,9 @@ row_is_in_frame(WindowObject winobj, int64 pos, TupleTableSlot *slot,
                        /* following row that is not peer is out of frame */
                        if (pos > winstate->currentpos)
                        {
-                               if (fetch_tuple)
-                                       window_gettupleslot(winobj, pos, slot);
+                               if (fetch_tuple)        /* need to fetch tuple? */
+                                       if (!window_gettupleslot(winobj, pos, slot))
+                                               return -1;
                                if (!are_peers(winstate, slot, winstate->ss.ss_ScanTupleSlot))
                                        return -1;
                        }
@@ -3721,6 +3722,7 @@ WinGetFuncArgInPartition(WindowObject winobj, int argno,
        int                     notnull_offset;
        int                     notnull_relpos;
        int                     forward;
+       bool            myisout;
 
        Assert(WindowObjectIsValid(winobj));
        winstate = winobj->winstate;
@@ -3759,63 +3761,60 @@ WinGetFuncArgInPartition(WindowObject winobj, int argno,
 
        if (!null_treatment)            /* IGNORE NULLS is not specified */
        {
+               /* get tupple and evaluate in a partition */
                datum = gettuple_eval_partition(winobj, argno,
-                                                                               abs_pos, isnull, isout);
-               if (!*isout && set_mark)
+                                                                               abs_pos, isnull, &myisout);
+               if (!myisout && set_mark)
                        WinSetMarkPosition(winobj, abs_pos);
+               if (isout)
+                       *isout = myisout;
                return datum;
        }
 
+       myisout = false;
+       datum = 0;
+
        /*
         * Get the next nonnull value in the partition, moving forward or backward
         * until we find a value or reach the partition's end.
         */
        do
        {
+               int                     nn_info;        /* NOT NULL info */
+
                abs_pos += forward;
-               if (abs_pos < 0)
-               {
-                       /* out of partition */
-                       if (isout)
-                               *isout = true;
-                       *isnull = true;
-                       datum = 0;
+               if (abs_pos < 0)                /* apparently out of partition */
                        break;
-               }
 
-               switch (get_notnull_info(winobj, abs_pos))
+               /* check NOT NULL cached info */
+               nn_info = get_notnull_info(winobj, abs_pos);
+               if (nn_info == NN_NOTNULL)      /* this row is known to be NOT NULL */
+                       notnull_offset++;
+
+               else if (nn_info == NN_NULL)    /* this row is known to be NULL */
+                       continue;                       /* keep on moving forward or backward */
+
+               else                                    /* need to check NULL or not */
                {
-                       case NN_NOTNULL:        /* this row is known to be NOT NULL */
-                               notnull_offset++;
-                               if (notnull_offset >= notnull_relpos)
-                               {
-                                       /* prepare to exit this loop */
-                                       datum = gettuple_eval_partition(winobj, argno,
-                                                                                                       abs_pos, isnull, isout);
-                               }
-                               break;
-                       case NN_NULL:           /* this row is known to be NULL */
-                               if (isout)
-                                       *isout = false;
-                               *isnull = true;
-                               datum = 0;
-                               break;
-                       default:                        /* need to check NULL or not */
-                               datum = gettuple_eval_partition(winobj, argno,
-                                                                                               abs_pos, isnull, isout);
-                               if (*isout)             /* out of partition? */
-                                       return datum;
-
-                               if (!*isnull)
-                                       notnull_offset++;
-                               /* record the row status */
-                               put_notnull_info(winobj, abs_pos, *isnull);
+                       /* get tupple and evaluate in a partition */
+                       datum = gettuple_eval_partition(winobj, argno,
+                                                                                       abs_pos, isnull, &myisout);
+                       if (myisout)            /* out of partition? */
                                break;
+                       if (!*isnull)
+                               notnull_offset++;
+                       /* record the row status */
+                       put_notnull_info(winobj, abs_pos, *isnull);
                }
        } while (notnull_offset < notnull_relpos);
 
-       if (!*isout && set_mark)
+       /* get tupple and evaluate in a partition */
+       datum = gettuple_eval_partition(winobj, argno,
+                                                                       abs_pos, isnull, &myisout);
+       if (!myisout && set_mark)
                WinSetMarkPosition(winobj, abs_pos);
+       if (isout)
+               *isout = myisout;
 
        return datum;
 }