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Fix error handling in pltcl_returnnext.

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We can't throw elog(ERROR) out of a Tcl command procedure; we have
to catch the error and return TCL_ERROR to the Tcl interpreter.
pltcl_returnnext failed to meet this requirement, so that errors
detected by pltcl_build_tuple_result or other functions called here
led to longjmp'ing out of the Tcl interpreter and thereby leaving it
in a bad state.  Use the existing subtransaction support to prevent
that.  Oversight in commit 26abb50c4, found more or less accidentally
by the buildfarm thanks to the tests added in 961bed020.

Report: https://postgr.es/m/30647.1483989734@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2017-01-09 17:47:02 -05:00
parent 3957b58b88
commit 8c5722948e
1 changed files with 59 additions and 40 deletions
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99
src/pl/tcl/pltcl.c
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@ -299,6 +299,14 @@ static int pltcl_SPI_execute_plan(ClientData cdata, Tcl_Interp *interp,
static int pltcl_SPI_lastoid(ClientData cdata, Tcl_Interp *interp,
int objc, Tcl_Obj *const objv[]);
static void pltcl_subtrans_begin(MemoryContext oldcontext,
ResourceOwner oldowner);
static void pltcl_subtrans_commit(MemoryContext oldcontext,
ResourceOwner oldowner);
static void pltcl_subtrans_abort(Tcl_Interp *interp,
MemoryContext oldcontext,
ResourceOwner oldowner);
static void pltcl_set_tuple_values(Tcl_Interp *interp, const char *arrayname,
uint64 tupno, HeapTuple tuple, TupleDesc tupdesc);
static Tcl_Obj *pltcl_build_tuple_argument(HeapTuple tuple, TupleDesc tupdesc);
@ -2073,9 +2081,9 @@ pltcl_returnnext(ClientData cdata, Tcl_Interp *interp,
pltcl_call_state *call_state = pltcl_current_call_state;
FunctionCallInfo fcinfo = call_state->fcinfo;
pltcl_proc_desc *prodesc = call_state->prodesc;
int result = TCL_OK;
MemoryContext tmpcxt;
MemoryContext oldcxt;
MemoryContext oldcontext = CurrentMemoryContext;
ResourceOwner oldowner = CurrentResourceOwner;
volatile int result = TCL_OK;
/*
* Check that we're called as a set-returning function
@ -2103,52 +2111,63 @@ pltcl_returnnext(ClientData cdata, Tcl_Interp *interp,
return TCL_ERROR;
}
/* Set up tuple store if first output row */
if (call_state->tuple_store == NULL)
pltcl_init_tuple_store(call_state);
/* Make short-lived context to run input functions in */
tmpcxt = AllocSetContextCreate(CurrentMemoryContext,
"pltcl_returnnext",
ALLOCSET_SMALL_SIZES);
oldcxt = MemoryContextSwitchTo(tmpcxt);
if (prodesc->fn_retistuple)
/*
* The rest might throw elog(ERROR), so must run in a subtransaction.
*
* A small advantage of using a subtransaction is that it provides a
* short-lived memory context for free, so we needn't worry about leaking
* memory here. To use that context, call BeginInternalSubTransaction
* directly instead of going through pltcl_subtrans_begin.
*/
BeginInternalSubTransaction(NULL);
PG_TRY();
{
Tcl_Obj **rowObjv;
int rowObjc;
/* Set up tuple store if first output row */
if (call_state->tuple_store == NULL)
pltcl_init_tuple_store(call_state);
/* result should be a list, so break it down */
if (Tcl_ListObjGetElements(interp, objv[1], &rowObjc, &rowObjv) == TCL_ERROR)
result = TCL_ERROR;
if (prodesc->fn_retistuple)
{
Tcl_Obj **rowObjv;
int rowObjc;
/* result should be a list, so break it down */
if (Tcl_ListObjGetElements(interp, objv[1], &rowObjc, &rowObjv) == TCL_ERROR)
result = TCL_ERROR;
else
{
HeapTuple tuple;
tuple = pltcl_build_tuple_result(interp, rowObjv, rowObjc,
call_state);
tuplestore_puttuple(call_state->tuple_store, tuple);
}
}
else
{
HeapTuple tuple;
Datum retval;
bool isNull = false;
tuple = pltcl_build_tuple_result(interp, rowObjv, rowObjc,
call_state);
tuplestore_puttuple(call_state->tuple_store, tuple);
/* for paranoia's sake, check that tupdesc has exactly one column */
if (call_state->ret_tupdesc->natts != 1)
elog(ERROR, "wrong result type supplied in return_next");
retval = InputFunctionCall(&prodesc->result_in_func,
utf_u2e((char *) Tcl_GetString(objv[1])),
prodesc->result_typioparam,
-1);
tuplestore_putvalues(call_state->tuple_store, call_state->ret_tupdesc,
&retval, &isNull);
}
pltcl_subtrans_commit(oldcontext, oldowner);
}
else
PG_CATCH();
{
Datum retval;
bool isNull = false;
/* for paranoia's sake, check that tupdesc has exactly one column */
if (call_state->ret_tupdesc->natts != 1)
elog(ERROR, "wrong result type supplied in return_next");
retval = InputFunctionCall(&prodesc->result_in_func,
utf_u2e((char *) Tcl_GetString(objv[1])),
prodesc->result_typioparam,
-1);
tuplestore_putvalues(call_state->tuple_store, call_state->ret_tupdesc,
&retval, &isNull);
pltcl_subtrans_abort(interp, oldcontext, oldowner);
return TCL_ERROR;
}
MemoryContextSwitchTo(oldcxt);
MemoryContextDelete(tmpcxt);
PG_END_TRY();
return result;
}