Use heap_modify_tuple not SPI_modifytuple in pl/python triggers.

The code here would need some change anyway given planned change in
SPI_modifytuple semantics, since this executes after we've exited the
SPI environment.  But really it's better to just use heap_modify_tuple.

While at it, normalize use of SPI_fnumber: make error messages distinguish
no-such-column from can't-set-system-column, and remove test for deleted
column which is going to migrate into SPI_fnumber.  The lack of a check
for system column names is actually a pre-existing bug here, and might
even qualify as a security bug except that we don't have any trusted
version of plpython.

diff --git a/src/pl/plpython/plpy_exec.c b/src/pl/plpython/plpy_exec.c
index fa583fab164d1c3fec4d2b17a16300a39d360ba8..fa5b25a5fade10047fba63df98a433cbedc96caf 100644 (file)
--- a/src/pl/plpython/plpy_exec.c
+++ b/src/pl/plpython/plpy_exec.c
@@ -896,18 +896,13 @@ static HeapTuple
 PLy_modify_tuple(PLyProcedure *proc, PyObject *pltd, TriggerData *tdata,
                                 HeapTuple otup)
 {
+       HeapTuple       rtup;
        PyObject   *volatile plntup;
        PyObject   *volatile plkeys;
        PyObject   *volatile plval;
-       HeapTuple       rtup;
-       int                     natts,
-                               i,
-                               attn,
-                               atti;
-       int                *volatile modattrs;
        Datum      *volatile modvalues;
-       char       *volatile modnulls;
-       TupleDesc       tupdesc;
+       bool       *volatile modnulls;
+       bool       *volatile modrepls;
        ErrorContextCallback plerrcontext;
 
        plerrcontext.callback = plpython_trigger_error_callback;
@@ -915,12 +910,16 @@ PLy_modify_tuple(PLyProcedure *proc, PyObject *pltd, TriggerData *tdata,
        error_context_stack = &plerrcontext;
 
        plntup = plkeys = plval = NULL;
-       modattrs = NULL;
        modvalues = NULL;
        modnulls = NULL;
+       modrepls = NULL;
 
        PG_TRY();
        {
+               TupleDesc       tupdesc;
+               int                     nkeys,
+                                       i;
+
                if ((plntup = PyDict_GetItemString(pltd, "new")) == NULL)
                        ereport(ERROR,
                                        (errcode(ERRCODE_UNDEFINED_OBJECT),
@@ -932,18 +931,20 @@ PLy_modify_tuple(PLyProcedure *proc, PyObject *pltd, TriggerData *tdata,
                                         errmsg("TD[\"new\"] is not a dictionary")));
 
                plkeys = PyDict_Keys(plntup);
-               natts = PyList_Size(plkeys);
-
-               modattrs = (int *) palloc(natts * sizeof(int));
-               modvalues = (Datum *) palloc(natts * sizeof(Datum));
-               modnulls = (char *) palloc(natts * sizeof(char));
+               nkeys = PyList_Size(plkeys);
 
                tupdesc = tdata->tg_relation->rd_att;
 
-               for (i = 0; i < natts; i++)
+               modvalues = (Datum *) palloc0(tupdesc->natts * sizeof(Datum));
+               modnulls = (bool *) palloc0(tupdesc->natts * sizeof(bool));
+               modrepls = (bool *) palloc0(tupdesc->natts * sizeof(bool));
+
+               for (i = 0; i < nkeys; i++)
                {
                        PyObject   *platt;
                        char       *plattstr;
+                       int                     attn;
+                       PLyObToDatum *att;
 
                        platt = PyList_GetItem(plkeys, i);
                        if (PyString_Check(platt))
@@ -963,7 +964,12 @@ PLy_modify_tuple(PLyProcedure *proc, PyObject *pltd, TriggerData *tdata,
                                                (errcode(ERRCODE_UNDEFINED_COLUMN),
                                                 errmsg("key \"%s\" found in TD[\"new\"] does not exist as a column in the triggering row",
                                                                plattstr)));
-                       atti = attn - 1;
+                       if (attn <= 0)
+                               ereport(ERROR,
+                                               (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                                                errmsg("cannot set system attribute \"%s\"",
+                                                               plattstr)));
+                       att = &proc->result.out.r.atts[attn - 1];
 
                        plval = PyDict_GetItem(plntup, platt);
                        if (plval == NULL)
@@ -971,41 +977,31 @@ PLy_modify_tuple(PLyProcedure *proc, PyObject *pltd, TriggerData *tdata,
 
                        Py_INCREF(plval);
 
-                       modattrs[i] = attn;
-
-                       if (tupdesc->attrs[atti]->attisdropped)
-                       {
-                               modvalues[i] = (Datum) 0;
-                               modnulls[i] = 'n';
-                       }
-                       else if (plval != Py_None)
+                       if (plval != Py_None)
                        {
-                               PLyObToDatum *att = &proc->result.out.r.atts[atti];
-
-                               modvalues[i] = (att->func) (att,
-                                                                                       tupdesc->attrs[atti]->atttypmod,
-                                                                                       plval,
-                                                                                       false);
-                               modnulls[i] = ' ';
+                               modvalues[attn - 1] =
+                                       (att->func) (att,
+                                                                tupdesc->attrs[attn - 1]->atttypmod,
+                                                                plval,
+                                                                false);
+                               modnulls[attn - 1] = false;
                        }
                        else
                        {
-                               modvalues[i] =
-                                       InputFunctionCall(&proc->result.out.r.atts[atti].typfunc,
+                               modvalues[attn - 1] =
+                                       InputFunctionCall(&att->typfunc,
                                                                          NULL,
-                                                                       proc->result.out.r.atts[atti].typioparam,
-                                                                         tupdesc->attrs[atti]->atttypmod);
-                               modnulls[i] = 'n';
+                                                                         att->typioparam,
+                                                                         tupdesc->attrs[attn - 1]->atttypmod);
+                               modnulls[attn - 1] = true;
                        }
+                       modrepls[attn - 1] = true;
 
                        Py_DECREF(plval);
                        plval = NULL;
                }
 
-               rtup = SPI_modifytuple(tdata->tg_relation, otup, natts,
-                                                          modattrs, modvalues, modnulls);
-               if (rtup == NULL)
-                       elog(ERROR, "SPI_modifytuple failed: error %d", SPI_result);
+               rtup = heap_modify_tuple(otup, tupdesc, modvalues, modnulls, modrepls);
        }
        PG_CATCH();
        {
@@ -1013,12 +1009,12 @@ PLy_modify_tuple(PLyProcedure *proc, PyObject *pltd, TriggerData *tdata,
                Py_XDECREF(plkeys);
                Py_XDECREF(plval);
 
-               if (modnulls)
-                       pfree(modnulls);
                if (modvalues)
                        pfree(modvalues);
-               if (modattrs)
-                       pfree(modattrs);
+               if (modnulls)
+                       pfree(modnulls);
+               if (modrepls)
+                       pfree(modrepls);
 
                PG_RE_THROW();
        }
@@ -1027,9 +1023,9 @@ PLy_modify_tuple(PLyProcedure *proc, PyObject *pltd, TriggerData *tdata,
        Py_DECREF(plntup);
        Py_DECREF(plkeys);
 
-       pfree(modattrs);
        pfree(modvalues);
        pfree(modnulls);
+       pfree(modrepls);
 
        error_context_stack = plerrcontext.previous;