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;