granicus.if.org Git - postgresql/blob - src/backend/executor/functions.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * functions.c
   4  *        Execution of SQL-language functions
   5  *
   6  * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        src/backend/executor/functions.c
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 #include "postgres.h"
  16
  17 #include "access/htup_details.h"
  18 #include "access/xact.h"
  19 #include "catalog/pg_proc.h"
  20 #include "catalog/pg_type.h"
  21 #include "executor/functions.h"
  22 #include "funcapi.h"
  23 #include "miscadmin.h"
  24 #include "nodes/makefuncs.h"
  25 #include "nodes/nodeFuncs.h"
  26 #include "parser/parse_coerce.h"
  27 #include "parser/parse_func.h"
  28 #include "storage/proc.h"
  29 #include "tcop/utility.h"
  30 #include "utils/builtins.h"
  31 #include "utils/datum.h"
  32 #include "utils/lsyscache.h"
  33 #include "utils/memutils.h"
  34 #include "utils/snapmgr.h"
  35 #include "utils/syscache.h"
  36
  37
  38 /*
  39  * Specialized DestReceiver for collecting query output in a SQL function
  40  */
  41 typedef struct
  42 {
  43         DestReceiver pub;                       /* publicly-known function pointers */
  44         Tuplestorestate *tstore;        /* where to put result tuples */
  45         MemoryContext cxt;                      /* context containing tstore */
  46         JunkFilter *filter;                     /* filter to convert tuple type */
  47 } DR_sqlfunction;
  48
  49 /*
  50  * We have an execution_state record for each query in a function.  Each
  51  * record contains a plantree for its query.  If the query is currently in
  52  * F_EXEC_RUN state then there's a QueryDesc too.
  53  *
  54  * The "next" fields chain together all the execution_state records generated
  55  * from a single original parsetree.  (There will only be more than one in
  56  * case of rule expansion of the original parsetree.)
  57  */
  58 typedef enum
  59 {
  60         F_EXEC_START, F_EXEC_RUN, F_EXEC_DONE
  61 } ExecStatus;
  62
  63 typedef struct execution_state
  64 {
  65         struct execution_state *next;
  66         ExecStatus      status;
  67         bool            setsResult;             /* true if this query produces func's result */
  68         bool            lazyEval;               /* true if should fetch one row at a time */
  69         PlannedStmt *stmt;                      /* plan for this query */
  70         QueryDesc  *qd;                         /* null unless status == RUN */
  71 } execution_state;
  72
  73
  74 /*
  75  * An SQLFunctionCache record is built during the first call,
  76  * and linked to from the fn_extra field of the FmgrInfo struct.
  77  *
  78  * Note that currently this has only the lifespan of the calling query.
  79  * Someday we should rewrite this code to use plancache.c to save parse/plan
  80  * results for longer than that.
  81  *
  82  * Physically, though, the data has the lifespan of the FmgrInfo that's used
  83  * to call the function, and there are cases (particularly with indexes)
  84  * where the FmgrInfo might survive across transactions.  We cannot assume
  85  * that the parse/plan trees are good for longer than the (sub)transaction in
  86  * which parsing was done, so we must mark the record with the LXID/subxid of
  87  * its creation time, and regenerate everything if that's obsolete.  To avoid
  88  * memory leakage when we do have to regenerate things, all the data is kept
  89  * in a sub-context of the FmgrInfo's fn_mcxt.
  90  */
  91 typedef struct
  92 {
  93         char       *fname;                      /* function name (for error msgs) */
  94         char       *src;                        /* function body text (for error msgs) */
  95
  96         SQLFunctionParseInfoPtr pinfo;          /* data for parser callback hooks */
  97
  98         Oid                     rettype;                /* actual return type */
  99         int16           typlen;                 /* length of the return type */
 100         bool            typbyval;               /* true if return type is pass by value */
 101         bool            returnsSet;             /* true if returning multiple rows */
 102         bool            returnsTuple;   /* true if returning whole tuple result */
 103         bool            shutdown_reg;   /* true if registered shutdown callback */
 104         bool            readonly_func;  /* true to run in "read only" mode */
 105         bool            lazyEval;               /* true if using lazyEval for result query */
 106
 107         ParamListInfo paramLI;          /* Param list representing current args */
 108
 109         Tuplestorestate *tstore;        /* where we accumulate result tuples */
 110
 111         JunkFilter *junkFilter;         /* will be NULL if function returns VOID */
 112
 113         /*
 114          * func_state is a List of execution_state records, each of which is the
 115          * first for its original parsetree, with any additional records chained
 116          * to it via the "next" fields.  This sublist structure is needed to keep
 117          * track of where the original query boundaries are.
 118          */
 119         List       *func_state;
 120
 121         MemoryContext fcontext;         /* memory context holding this struct and all
 122                                                                  * subsidiary data */
 123
 124         LocalTransactionId lxid;        /* lxid in which cache was made */
 125         SubTransactionId subxid;        /* subxid in which cache was made */
 126 } SQLFunctionCache;
 127
 128 typedef SQLFunctionCache *SQLFunctionCachePtr;
 129
 130 /*
 131  * Data structure needed by the parser callback hooks to resolve parameter
 132  * references during parsing of a SQL function's body.  This is separate from
 133  * SQLFunctionCache since we sometimes do parsing separately from execution.
 134  */
 135 typedef struct SQLFunctionParseInfo
 136 {
 137         char       *fname;                      /* function's name */
 138         int                     nargs;                  /* number of input arguments */
 139         Oid                *argtypes;           /* resolved types of input arguments */
 140         char      **argnames;           /* names of input arguments; NULL if none */
 141         /* Note that argnames[i] can be NULL, if some args are unnamed */
 142         Oid                     collation;              /* function's input collation, if known */
 143 }       SQLFunctionParseInfo;
 144
 145
 146 /* non-export function prototypes */
 147 static Node *sql_fn_param_ref(ParseState *pstate, ParamRef *pref);
 148 static Node *sql_fn_post_column_ref(ParseState *pstate,
 149                                            ColumnRef *cref, Node *var);
 150 static Node *sql_fn_make_param(SQLFunctionParseInfoPtr pinfo,
 151                                   int paramno, int location);
 152 static Node *sql_fn_resolve_param_name(SQLFunctionParseInfoPtr pinfo,
 153                                                   const char *paramname, int location);
 154 static List *init_execution_state(List *queryTree_list,
 155                                          SQLFunctionCachePtr fcache,
 156                                          bool lazyEvalOK);
 157 static void init_sql_fcache(FmgrInfo *finfo, Oid collation, bool lazyEvalOK);
 158 static void postquel_start(execution_state *es, SQLFunctionCachePtr fcache);
 159 static bool postquel_getnext(execution_state *es, SQLFunctionCachePtr fcache);
 160 static void postquel_end(execution_state *es);
 161 static void postquel_sub_params(SQLFunctionCachePtr fcache,
 162                                         FunctionCallInfo fcinfo);
 163 static Datum postquel_get_single_result(TupleTableSlot *slot,
 164                                                    FunctionCallInfo fcinfo,
 165                                                    SQLFunctionCachePtr fcache,
 166                                                    MemoryContext resultcontext);
 167 static void sql_exec_error_callback(void *arg);
 168 static void ShutdownSQLFunction(Datum arg);
 169 static void sqlfunction_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
 170 static bool sqlfunction_receive(TupleTableSlot *slot, DestReceiver *self);
 171 static void sqlfunction_shutdown(DestReceiver *self);
 172 static void sqlfunction_destroy(DestReceiver *self);
 173
 174
 175 /*
 176  * Prepare the SQLFunctionParseInfo struct for parsing a SQL function body
 177  *
 178  * This includes resolving actual types of polymorphic arguments.
 179  *
 180  * call_expr can be passed as NULL, but then we will fail if there are any
 181  * polymorphic arguments.
 182  */
 183 SQLFunctionParseInfoPtr
 184 prepare_sql_fn_parse_info(HeapTuple procedureTuple,
 185                                                   Node *call_expr,
 186                                                   Oid inputCollation)
 187 {
 188         SQLFunctionParseInfoPtr pinfo;
 189         Form_pg_proc procedureStruct = (Form_pg_proc) GETSTRUCT(procedureTuple);
 190         int                     nargs;
 191
 192         pinfo = (SQLFunctionParseInfoPtr) palloc0(sizeof(SQLFunctionParseInfo));
 193
 194         /* Function's name (only) can be used to qualify argument names */
 195         pinfo->fname = pstrdup(NameStr(procedureStruct->proname));
 196
 197         /* Save the function's input collation */
 198         pinfo->collation = inputCollation;
 199
 200         /*
 201          * Copy input argument types from the pg_proc entry, then resolve any
 202          * polymorphic types.
 203          */
 204         pinfo->nargs = nargs = procedureStruct->pronargs;
 205         if (nargs > 0)
 206         {
 207                 Oid                *argOidVect;
 208                 int                     argnum;
 209
 210                 argOidVect = (Oid *) palloc(nargs * sizeof(Oid));
 211                 memcpy(argOidVect,
 212                            procedureStruct->proargtypes.values,
 213                            nargs * sizeof(Oid));
 214
 215                 for (argnum = 0; argnum < nargs; argnum++)
 216                 {
 217                         Oid                     argtype = argOidVect[argnum];
 218
 219                         if (IsPolymorphicType(argtype))
 220                         {
 221                                 argtype = get_call_expr_argtype(call_expr, argnum);
 222                                 if (argtype == InvalidOid)
 223                                         ereport(ERROR,
 224                                                         (errcode(ERRCODE_DATATYPE_MISMATCH),
 225                                                          errmsg("could not determine actual type of argument declared %s",
 226                                                                         format_type_be(argOidVect[argnum]))));
 227                                 argOidVect[argnum] = argtype;
 228                         }
 229                 }
 230
 231                 pinfo->argtypes = argOidVect;
 232         }
 233
 234         /*
 235          * Collect names of arguments, too, if any
 236          */
 237         if (nargs > 0)
 238         {
 239                 Datum           proargnames;
 240                 Datum           proargmodes;
 241                 int                     n_arg_names;
 242                 bool            isNull;
 243
 244                 proargnames = SysCacheGetAttr(PROCNAMEARGSNSP, procedureTuple,
 245                                                                           Anum_pg_proc_proargnames,
 246                                                                           &isNull);
 247                 if (isNull)
 248                         proargnames = PointerGetDatum(NULL);            /* just to be sure */
 249
 250                 proargmodes = SysCacheGetAttr(PROCNAMEARGSNSP, procedureTuple,
 251                                                                           Anum_pg_proc_proargmodes,
 252                                                                           &isNull);
 253                 if (isNull)
 254                         proargmodes = PointerGetDatum(NULL);            /* just to be sure */
 255
 256                 n_arg_names = get_func_input_arg_names(proargnames, proargmodes,
 257                                                                                            &pinfo->argnames);
 258
 259                 /* Paranoia: ignore the result if too few array entries */
 260                 if (n_arg_names < nargs)
 261                         pinfo->argnames = NULL;
 262         }
 263         else
 264                 pinfo->argnames = NULL;
 265
 266         return pinfo;
 267 }
 268
 269 /*
 270  * Parser setup hook for parsing a SQL function body.
 271  */
 272 void
 273 sql_fn_parser_setup(struct ParseState *pstate, SQLFunctionParseInfoPtr pinfo)
 274 {
 275         pstate->p_pre_columnref_hook = NULL;
 276         pstate->p_post_columnref_hook = sql_fn_post_column_ref;
 277         pstate->p_paramref_hook = sql_fn_param_ref;
 278         /* no need to use p_coerce_param_hook */
 279         pstate->p_ref_hook_state = (void *) pinfo;
 280 }
 281
 282 /*
 283  * sql_fn_post_column_ref               parser callback for ColumnRefs
 284  */
 285 static Node *
 286 sql_fn_post_column_ref(ParseState *pstate, ColumnRef *cref, Node *var)
 287 {
 288         SQLFunctionParseInfoPtr pinfo = (SQLFunctionParseInfoPtr) pstate->p_ref_hook_state;
 289         int                     nnames;
 290         Node       *field1;
 291         Node       *subfield = NULL;
 292         const char *name1;
 293         const char *name2 = NULL;
 294         Node       *param;
 295
 296         /*
 297          * Never override a table-column reference.  This corresponds to
 298          * considering the parameter names to appear in a scope outside the
 299          * individual SQL commands, which is what we want.
 300          */
 301         if (var != NULL)
 302                 return NULL;
 303
 304         /*----------
 305          * The allowed syntaxes are:
 306          *
 307          * A            A = parameter name
 308          * A.B          A = function name, B = parameter name
 309          *                      OR: A = record-typed parameter name, B = field name
 310          *                      (the first possibility takes precedence)
 311          * A.B.C        A = function name, B = record-typed parameter name,
 312          *                      C = field name
 313          * A.*          Whole-row reference to composite parameter A.
 314          * A.B.*        Same, with A = function name, B = parameter name
 315          *
 316          * Here, it's sufficient to ignore the "*" in the last two cases --- the
 317          * main parser will take care of expanding the whole-row reference.
 318          *----------
 319          */
 320         nnames = list_length(cref->fields);
 321
 322         if (nnames > 3)
 323                 return NULL;
 324
 325         if (IsA(llast(cref->fields), A_Star))
 326                 nnames--;
 327
 328         field1 = (Node *) linitial(cref->fields);
 329         Assert(IsA(field1, String));
 330         name1 = strVal(field1);
 331         if (nnames > 1)
 332         {
 333                 subfield = (Node *) lsecond(cref->fields);
 334                 Assert(IsA(subfield, String));
 335                 name2 = strVal(subfield);
 336         }
 337
 338         if (nnames == 3)
 339         {
 340                 /*
 341                  * Three-part name: if the first part doesn't match the function name,
 342                  * we can fail immediately. Otherwise, look up the second part, and
 343                  * take the third part to be a field reference.
 344                  */
 345                 if (strcmp(name1, pinfo->fname) != 0)
 346                         return NULL;
 347
 348                 param = sql_fn_resolve_param_name(pinfo, name2, cref->location);
 349
 350                 subfield = (Node *) lthird(cref->fields);
 351                 Assert(IsA(subfield, String));
 352         }
 353         else if (nnames == 2 && strcmp(name1, pinfo->fname) == 0)
 354         {
 355                 /*
 356                  * Two-part name with first part matching function name: first see if
 357                  * second part matches any parameter name.
 358                  */
 359                 param = sql_fn_resolve_param_name(pinfo, name2, cref->location);
 360
 361                 if (param)
 362                 {
 363                         /* Yes, so this is a parameter reference, no subfield */
 364                         subfield = NULL;
 365                 }
 366                 else
 367                 {
 368                         /* No, so try to match as parameter name and subfield */
 369                         param = sql_fn_resolve_param_name(pinfo, name1, cref->location);
 370                 }
 371         }
 372         else
 373         {
 374                 /* Single name, or parameter name followed by subfield */
 375                 param = sql_fn_resolve_param_name(pinfo, name1, cref->location);
 376         }
 377
 378         if (!param)
 379                 return NULL;                    /* No match */
 380
 381         if (subfield)
 382         {
 383                 /*
 384                  * Must be a reference to a field of a composite parameter; otherwise
 385                  * ParseFuncOrColumn will return NULL, and we'll fail back at the
 386                  * caller.
 387                  */
 388                 param = ParseFuncOrColumn(pstate,
 389                                                                   list_make1(subfield),
 390                                                                   list_make1(param),
 391                                                                   NULL,
 392                                                                   cref->location);
 393         }
 394
 395         return param;
 396 }
 397
 398 /*
 399  * sql_fn_param_ref             parser callback for ParamRefs ($n symbols)
 400  */
 401 static Node *
 402 sql_fn_param_ref(ParseState *pstate, ParamRef *pref)
 403 {
 404         SQLFunctionParseInfoPtr pinfo = (SQLFunctionParseInfoPtr) pstate->p_ref_hook_state;
 405         int                     paramno = pref->number;
 406
 407         /* Check parameter number is valid */
 408         if (paramno <= 0 || paramno > pinfo->nargs)
 409                 return NULL;                    /* unknown parameter number */
 410
 411         return sql_fn_make_param(pinfo, paramno, pref->location);
 412 }
 413
 414 /*
 415  * sql_fn_make_param            construct a Param node for the given paramno
 416  */
 417 static Node *
 418 sql_fn_make_param(SQLFunctionParseInfoPtr pinfo,
 419                                   int paramno, int location)
 420 {
 421         Param      *param;
 422
 423         param = makeNode(Param);
 424         param->paramkind = PARAM_EXTERN;
 425         param->paramid = paramno;
 426         param->paramtype = pinfo->argtypes[paramno - 1];
 427         param->paramtypmod = -1;
 428         param->paramcollid = get_typcollation(param->paramtype);
 429         param->location = location;
 430
 431         /*
 432          * If we have a function input collation, allow it to override the
 433          * type-derived collation for parameter symbols.  (XXX perhaps this should
 434          * not happen if the type collation is not default?)
 435          */
 436         if (OidIsValid(pinfo->collation) && OidIsValid(param->paramcollid))
 437                 param->paramcollid = pinfo->collation;
 438
 439         return (Node *) param;
 440 }
 441
 442 /*
 443  * Search for a function parameter of the given name; if there is one,
 444  * construct and return a Param node for it.  If not, return NULL.
 445  * Helper function for sql_fn_post_column_ref.
 446  */
 447 static Node *
 448 sql_fn_resolve_param_name(SQLFunctionParseInfoPtr pinfo,
 449                                                   const char *paramname, int location)
 450 {
 451         int                     i;
 452
 453         if (pinfo->argnames == NULL)
 454                 return NULL;
 455
 456         for (i = 0; i < pinfo->nargs; i++)
 457         {
 458                 if (pinfo->argnames[i] && strcmp(pinfo->argnames[i], paramname) == 0)
 459                         return sql_fn_make_param(pinfo, i + 1, location);
 460         }
 461
 462         return NULL;
 463 }
 464
 465 /*
 466  * Set up the per-query execution_state records for a SQL function.
 467  *
 468  * The input is a List of Lists of parsed and rewritten, but not planned,
 469  * querytrees.  The sublist structure denotes the original query boundaries.
 470  */
 471 static List *
 472 init_execution_state(List *queryTree_list,
 473                                          SQLFunctionCachePtr fcache,
 474                                          bool lazyEvalOK)
 475 {
 476         List       *eslist = NIL;
 477         execution_state *lasttages = NULL;
 478         ListCell   *lc1;
 479
 480         foreach(lc1, queryTree_list)
 481         {
 482                 List       *qtlist = castNode(List, lfirst(lc1));
 483                 execution_state *firstes = NULL;
 484                 execution_state *preves = NULL;
 485                 ListCell   *lc2;
 486
 487                 foreach(lc2, qtlist)
 488                 {
 489                         Query      *queryTree = castNode(Query, lfirst(lc2));
 490                         PlannedStmt *stmt;
 491                         execution_state *newes;
 492
 493                         /* Plan the query if needed */
 494                         if (queryTree->commandType == CMD_UTILITY)
 495                         {
 496                                 /* Utility commands require no planning. */
 497                                 stmt = makeNode(PlannedStmt);
 498                                 stmt->commandType = CMD_UTILITY;
 499                                 stmt->canSetTag = queryTree->canSetTag;
 500                                 stmt->utilityStmt = queryTree->utilityStmt;
 501                                 stmt->stmt_location = queryTree->stmt_location;
 502                                 stmt->stmt_len = queryTree->stmt_len;
 503                         }
 504                         else
 505                                 stmt = pg_plan_query(queryTree,
 506                                                                          CURSOR_OPT_PARALLEL_OK,
 507                                                                          NULL);
 508
 509                         /*
 510                          * Precheck all commands for validity in a function.  This should
 511                          * generally match the restrictions spi.c applies.
 512                          */
 513                         if (stmt->commandType == CMD_UTILITY)
 514                         {
 515                                 if (IsA(stmt->utilityStmt, CopyStmt) &&
 516                                         ((CopyStmt *) stmt->utilityStmt)->filename == NULL)
 517                                         ereport(ERROR,
 518                                                         (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 519                                         errmsg("cannot COPY to/from client in a SQL function")));
 520
 521                                 if (IsA(stmt->utilityStmt, TransactionStmt))
 522                                         ereport(ERROR,
 523                                                         (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 524                                         /* translator: %s is a SQL statement name */
 525                                                          errmsg("%s is not allowed in a SQL function",
 526                                                                         CreateCommandTag(stmt->utilityStmt))));
 527                         }
 528
 529                         if (fcache->readonly_func && !CommandIsReadOnly(stmt))
 530                                 ereport(ERROR,
 531                                                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 532                                 /* translator: %s is a SQL statement name */
 533                                            errmsg("%s is not allowed in a non-volatile function",
 534                                                           CreateCommandTag((Node *) stmt))));
 535
 536                         if (IsInParallelMode() && !CommandIsReadOnly(stmt))
 537                                 PreventCommandIfParallelMode(CreateCommandTag((Node *) stmt));
 538
 539                         /* OK, build the execution_state for this query */
 540                         newes = (execution_state *) palloc(sizeof(execution_state));
 541                         if (preves)
 542                                 preves->next = newes;
 543                         else
 544                                 firstes = newes;
 545
 546                         newes->next = NULL;
 547                         newes->status = F_EXEC_START;
 548                         newes->setsResult = false;      /* might change below */
 549                         newes->lazyEval = false;        /* might change below */
 550                         newes->stmt = stmt;
 551                         newes->qd = NULL;
 552
 553                         if (queryTree->canSetTag)
 554                                 lasttages = newes;
 555
 556                         preves = newes;
 557                 }
 558
 559                 eslist = lappend(eslist, firstes);
 560         }
 561
 562         /*
 563          * Mark the last canSetTag query as delivering the function result; then,
 564          * if it is a plain SELECT, mark it for lazy evaluation. If it's not a
 565          * SELECT we must always run it to completion.
 566          *
 567          * Note: at some point we might add additional criteria for whether to use
 568          * lazy eval.  However, we should prefer to use it whenever the function
 569          * doesn't return set, since fetching more than one row is useless in that
 570          * case.
 571          *
 572          * Note: don't set setsResult if the function returns VOID, as evidenced
 573          * by not having made a junkfilter.  This ensures we'll throw away any
 574          * output from a utility statement that check_sql_fn_retval deemed to not
 575          * have output.
 576          */
 577         if (lasttages && fcache->junkFilter)
 578         {
 579                 lasttages->setsResult = true;
 580                 if (lazyEvalOK &&
 581                         lasttages->stmt->commandType == CMD_SELECT &&
 582                         !lasttages->stmt->hasModifyingCTE)
 583                         fcache->lazyEval = lasttages->lazyEval = true;
 584         }
 585
 586         return eslist;
 587 }
 588
 589 /*
 590  * Initialize the SQLFunctionCache for a SQL function
 591  */
 592 static void
 593 init_sql_fcache(FmgrInfo *finfo, Oid collation, bool lazyEvalOK)
 594 {
 595         Oid                     foid = finfo->fn_oid;
 596         MemoryContext fcontext;
 597         MemoryContext oldcontext;
 598         Oid                     rettype;
 599         HeapTuple       procedureTuple;
 600         Form_pg_proc procedureStruct;
 601         SQLFunctionCachePtr fcache;
 602         List       *raw_parsetree_list;
 603         List       *queryTree_list;
 604         List       *flat_query_list;
 605         ListCell   *lc;
 606         Datum           tmp;
 607         bool            isNull;
 608
 609         /*
 610          * Create memory context that holds all the SQLFunctionCache data.  It
 611          * must be a child of whatever context holds the FmgrInfo.
 612          */
 613         fcontext = AllocSetContextCreate(finfo->fn_mcxt,
 614                                                                          "SQL function data",
 615                                                                          ALLOCSET_DEFAULT_SIZES);
 616
 617         oldcontext = MemoryContextSwitchTo(fcontext);
 618
 619         /*
 620          * Create the struct proper, link it to fcontext and fn_extra.  Once this
 621          * is done, we'll be able to recover the memory after failure, even if the
 622          * FmgrInfo is long-lived.
 623          */
 624         fcache = (SQLFunctionCachePtr) palloc0(sizeof(SQLFunctionCache));
 625         fcache->fcontext = fcontext;
 626         finfo->fn_extra = (void *) fcache;
 627
 628         /*
 629          * get the procedure tuple corresponding to the given function Oid
 630          */
 631         procedureTuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(foid));
 632         if (!HeapTupleIsValid(procedureTuple))
 633                 elog(ERROR, "cache lookup failed for function %u", foid);
 634         procedureStruct = (Form_pg_proc) GETSTRUCT(procedureTuple);
 635
 636         /*
 637          * copy function name immediately for use by error reporting callback
 638          */
 639         fcache->fname = pstrdup(NameStr(procedureStruct->proname));
 640
 641         /*
 642          * get the result type from the procedure tuple, and check for polymorphic
 643          * result type; if so, find out the actual result type.
 644          */
 645         rettype = procedureStruct->prorettype;
 646
 647         if (IsPolymorphicType(rettype))
 648         {
 649                 rettype = get_fn_expr_rettype(finfo);
 650                 if (rettype == InvalidOid)              /* this probably should not happen */
 651                         ereport(ERROR,
 652                                         (errcode(ERRCODE_DATATYPE_MISMATCH),
 653                                          errmsg("could not determine actual result type for function declared to return type %s",
 654                                                         format_type_be(procedureStruct->prorettype))));
 655         }
 656
 657         fcache->rettype = rettype;
 658
 659         /* Fetch the typlen and byval info for the result type */
 660         get_typlenbyval(rettype, &fcache->typlen, &fcache->typbyval);
 661
 662         /* Remember whether we're returning setof something */
 663         fcache->returnsSet = procedureStruct->proretset;
 664
 665         /* Remember if function is STABLE/IMMUTABLE */
 666         fcache->readonly_func =
 667                 (procedureStruct->provolatile != PROVOLATILE_VOLATILE);
 668
 669         /*
 670          * We need the actual argument types to pass to the parser.  Also make
 671          * sure that parameter symbols are considered to have the function's
 672          * resolved input collation.
 673          */
 674         fcache->pinfo = prepare_sql_fn_parse_info(procedureTuple,
 675                                                                                           finfo->fn_expr,
 676                                                                                           collation);
 677
 678         /*
 679          * And of course we need the function body text.
 680          */
 681         tmp = SysCacheGetAttr(PROCOID,
 682                                                   procedureTuple,
 683                                                   Anum_pg_proc_prosrc,
 684                                                   &isNull);
 685         if (isNull)
 686                 elog(ERROR, "null prosrc for function %u", foid);
 687         fcache->src = TextDatumGetCString(tmp);
 688
 689         /*
 690          * Parse and rewrite the queries in the function text.  Use sublists to
 691          * keep track of the original query boundaries.  But we also build a
 692          * "flat" list of the rewritten queries to pass to check_sql_fn_retval.
 693          * This is because the last canSetTag query determines the result type
 694          * independently of query boundaries --- and it might not be in the last
 695          * sublist, for example if the last query rewrites to DO INSTEAD NOTHING.
 696          * (It might not be unreasonable to throw an error in such a case, but
 697          * this is the historical behavior and it doesn't seem worth changing.)
 698          *
 699          * Note: since parsing and planning is done in fcontext, we will generate
 700          * a lot of cruft that lives as long as the fcache does.  This is annoying
 701          * but we'll not worry about it until the module is rewritten to use
 702          * plancache.c.
 703          */
 704         raw_parsetree_list = pg_parse_query(fcache->src);
 705
 706         queryTree_list = NIL;
 707         flat_query_list = NIL;
 708         foreach(lc, raw_parsetree_list)
 709         {
 710                 RawStmt    *parsetree = castNode(RawStmt, lfirst(lc));
 711                 List       *queryTree_sublist;
 712
 713                 queryTree_sublist = pg_analyze_and_rewrite_params(parsetree,
 714                                                                                                                   fcache->src,
 715                                                                            (ParserSetupHook) sql_fn_parser_setup,
 716                                                                                                                   fcache->pinfo);
 717                 queryTree_list = lappend(queryTree_list, queryTree_sublist);
 718                 flat_query_list = list_concat(flat_query_list,
 719                                                                           list_copy(queryTree_sublist));
 720         }
 721
 722         /*
 723          * Check that the function returns the type it claims to.  Although in
 724          * simple cases this was already done when the function was defined, we
 725          * have to recheck because database objects used in the function's queries
 726          * might have changed type.  We'd have to do it anyway if the function had
 727          * any polymorphic arguments.
 728          *
 729          * Note: we set fcache->returnsTuple according to whether we are returning
 730          * the whole tuple result or just a single column.  In the latter case we
 731          * clear returnsTuple because we need not act different from the scalar
 732          * result case, even if it's a rowtype column.  (However, we have to force
 733          * lazy eval mode in that case; otherwise we'd need extra code to expand
 734          * the rowtype column into multiple columns, since we have no way to
 735          * notify the caller that it should do that.)
 736          *
 737          * check_sql_fn_retval will also construct a JunkFilter we can use to
 738          * coerce the returned rowtype to the desired form (unless the result type
 739          * is VOID, in which case there's nothing to coerce to).
 740          */
 741         fcache->returnsTuple = check_sql_fn_retval(foid,
 742                                                                                            rettype,
 743                                                                                            flat_query_list,
 744                                                                                            NULL,
 745                                                                                            &fcache->junkFilter);
 746
 747         if (fcache->returnsTuple)
 748         {
 749                 /* Make sure output rowtype is properly blessed */
 750                 BlessTupleDesc(fcache->junkFilter->jf_resultSlot->tts_tupleDescriptor);
 751         }
 752         else if (fcache->returnsSet && type_is_rowtype(fcache->rettype))
 753         {
 754                 /*
 755                  * Returning rowtype as if it were scalar --- materialize won't work.
 756                  * Right now it's sufficient to override any caller preference for
 757                  * materialize mode, but to add more smarts in init_execution_state
 758                  * about this, we'd probably need a three-way flag instead of bool.
 759                  */
 760                 lazyEvalOK = true;
 761         }
 762
 763         /* Finally, plan the queries */
 764         fcache->func_state = init_execution_state(queryTree_list,
 765                                                                                           fcache,
 766                                                                                           lazyEvalOK);
 767
 768         /* Mark fcache with time of creation to show it's valid */
 769         fcache->lxid = MyProc->lxid;
 770         fcache->subxid = GetCurrentSubTransactionId();
 771
 772         ReleaseSysCache(procedureTuple);
 773
 774         MemoryContextSwitchTo(oldcontext);
 775 }
 776
 777 /* Start up execution of one execution_state node */
 778 static void
 779 postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
 780 {
 781         DestReceiver *dest;
 782
 783         Assert(es->qd == NULL);
 784
 785         /* Caller should have ensured a suitable snapshot is active */
 786         Assert(ActiveSnapshotSet());
 787
 788         /*
 789          * If this query produces the function result, send its output to the
 790          * tuplestore; else discard any output.
 791          */
 792         if (es->setsResult)
 793         {
 794                 DR_sqlfunction *myState;
 795
 796                 dest = CreateDestReceiver(DestSQLFunction);
 797                 /* pass down the needed info to the dest receiver routines */
 798                 myState = (DR_sqlfunction *) dest;
 799                 Assert(myState->pub.mydest == DestSQLFunction);
 800                 myState->tstore = fcache->tstore;
 801                 myState->cxt = CurrentMemoryContext;
 802                 myState->filter = fcache->junkFilter;
 803         }
 804         else
 805                 dest = None_Receiver;
 806
 807         es->qd = CreateQueryDesc(es->stmt,
 808                                                          fcache->src,
 809                                                          GetActiveSnapshot(),
 810                                                          InvalidSnapshot,
 811                                                          dest,
 812                                                          fcache->paramLI, 0);
 813
 814         /* Utility commands don't need Executor. */
 815         if (es->qd->operation != CMD_UTILITY)
 816         {
 817                 /*
 818                  * In lazyEval mode, do not let the executor set up an AfterTrigger
 819                  * context.  This is necessary not just an optimization, because we
 820                  * mustn't exit from the function execution with a stacked
 821                  * AfterTrigger level still active.  We are careful not to select
 822                  * lazyEval mode for any statement that could possibly queue triggers.
 823                  */
 824                 int                     eflags;
 825
 826                 if (es->lazyEval)
 827                         eflags = EXEC_FLAG_SKIP_TRIGGERS;
 828                 else
 829                         eflags = 0;                     /* default run-to-completion flags */
 830                 ExecutorStart(es->qd, eflags);
 831         }
 832
 833         es->status = F_EXEC_RUN;
 834 }
 835
 836 /* Run one execution_state; either to completion or to first result row */
 837 /* Returns true if we ran to completion */
 838 static bool
 839 postquel_getnext(execution_state *es, SQLFunctionCachePtr fcache)
 840 {
 841         bool            result;
 842
 843         if (es->qd->operation == CMD_UTILITY)
 844         {
 845                 ProcessUtility(es->qd->plannedstmt,
 846                                            fcache->src,
 847                                            PROCESS_UTILITY_QUERY,
 848                                            es->qd->params,
 849                                            es->qd->dest,
 850                                            NULL);
 851                 result = true;                  /* never stops early */
 852         }
 853         else
 854         {
 855                 /* Run regular commands to completion unless lazyEval */
 856                 uint64          count = (es->lazyEval) ? 1 : 0;
 857
 858                 ExecutorRun(es->qd, ForwardScanDirection, count, !fcache->returnsSet || !es->lazyEval);
 859
 860                 /*
 861                  * If we requested run to completion OR there was no tuple returned,
 862                  * command must be complete.
 863                  */
 864                 result = (count == 0 || es->qd->estate->es_processed == 0);
 865         }
 866
 867         return result;
 868 }
 869
 870 /* Shut down execution of one execution_state node */
 871 static void
 872 postquel_end(execution_state *es)
 873 {
 874         /* mark status done to ensure we don't do ExecutorEnd twice */
 875         es->status = F_EXEC_DONE;
 876
 877         /* Utility commands don't need Executor. */
 878         if (es->qd->operation != CMD_UTILITY)
 879         {
 880                 ExecutorFinish(es->qd);
 881                 ExecutorEnd(es->qd);
 882         }
 883
 884         (*es->qd->dest->rDestroy) (es->qd->dest);
 885
 886         FreeQueryDesc(es->qd);
 887         es->qd = NULL;
 888 }
 889
 890 /* Build ParamListInfo array representing current arguments */
 891 static void
 892 postquel_sub_params(SQLFunctionCachePtr fcache,
 893                                         FunctionCallInfo fcinfo)
 894 {
 895         int                     nargs = fcinfo->nargs;
 896
 897         if (nargs > 0)
 898         {
 899                 ParamListInfo paramLI;
 900                 int                     i;
 901
 902                 if (fcache->paramLI == NULL)
 903                 {
 904                         paramLI = (ParamListInfo)
 905                                 palloc(offsetof(ParamListInfoData, params) +
 906                                            nargs * sizeof(ParamExternData));
 907                         /* we have static list of params, so no hooks needed */
 908                         paramLI->paramFetch = NULL;
 909                         paramLI->paramFetchArg = NULL;
 910                         paramLI->parserSetup = NULL;
 911                         paramLI->parserSetupArg = NULL;
 912                         paramLI->numParams = nargs;
 913                         paramLI->paramMask = NULL;
 914                         fcache->paramLI = paramLI;
 915                 }
 916                 else
 917                 {
 918                         paramLI = fcache->paramLI;
 919                         Assert(paramLI->numParams == nargs);
 920                 }
 921
 922                 for (i = 0; i < nargs; i++)
 923                 {
 924                         ParamExternData *prm = &paramLI->params[i];
 925
 926                         prm->value = fcinfo->arg[i];
 927                         prm->isnull = fcinfo->argnull[i];
 928                         prm->pflags = 0;
 929                         prm->ptype = fcache->pinfo->argtypes[i];
 930                 }
 931         }
 932         else
 933                 fcache->paramLI = NULL;
 934 }
 935
 936 /*
 937  * Extract the SQL function's value from a single result row.  This is used
 938  * both for scalar (non-set) functions and for each row of a lazy-eval set
 939  * result.
 940  */
 941 static Datum
 942 postquel_get_single_result(TupleTableSlot *slot,
 943                                                    FunctionCallInfo fcinfo,
 944                                                    SQLFunctionCachePtr fcache,
 945                                                    MemoryContext resultcontext)
 946 {
 947         Datum           value;
 948         MemoryContext oldcontext;
 949
 950         /*
 951          * Set up to return the function value.  For pass-by-reference datatypes,
 952          * be sure to allocate the result in resultcontext, not the current memory
 953          * context (which has query lifespan).  We can't leave the data in the
 954          * TupleTableSlot because we intend to clear the slot before returning.
 955          */
 956         oldcontext = MemoryContextSwitchTo(resultcontext);
 957
 958         if (fcache->returnsTuple)
 959         {
 960                 /* We must return the whole tuple as a Datum. */
 961                 fcinfo->isnull = false;
 962                 value = ExecFetchSlotTupleDatum(slot);
 963         }
 964         else
 965         {
 966                 /*
 967                  * Returning a scalar, which we have to extract from the first column
 968                  * of the SELECT result, and then copy into result context if needed.
 969                  */
 970                 value = slot_getattr(slot, 1, &(fcinfo->isnull));
 971
 972                 if (!fcinfo->isnull)
 973                         value = datumCopy(value, fcache->typbyval, fcache->typlen);
 974         }
 975
 976         MemoryContextSwitchTo(oldcontext);
 977
 978         return value;
 979 }
 980
 981 /*
 982  * fmgr_sql: function call manager for SQL functions
 983  */
 984 Datum
 985 fmgr_sql(PG_FUNCTION_ARGS)
 986 {
 987         SQLFunctionCachePtr fcache;
 988         ErrorContextCallback sqlerrcontext;
 989         MemoryContext oldcontext;
 990         bool            randomAccess;
 991         bool            lazyEvalOK;
 992         bool            is_first;
 993         bool            pushed_snapshot;
 994         execution_state *es;
 995         TupleTableSlot *slot;
 996         Datum           result;
 997         List       *eslist;
 998         ListCell   *eslc;
 999
1000         /*
1001          * Setup error traceback support for ereport()
1002          */
1003         sqlerrcontext.callback = sql_exec_error_callback;
1004         sqlerrcontext.arg = fcinfo->flinfo;
1005         sqlerrcontext.previous = error_context_stack;
1006         error_context_stack = &sqlerrcontext;
1007
1008         /* Check call context */
1009         if (fcinfo->flinfo->fn_retset)
1010         {
1011                 ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
1012
1013                 /*
1014                  * For simplicity, we require callers to support both set eval modes.
1015                  * There are cases where we must use one or must use the other, and
1016                  * it's not really worthwhile to postpone the check till we know. But
1017                  * note we do not require caller to provide an expectedDesc.
1018                  */
1019                 if (!rsi || !IsA(rsi, ReturnSetInfo) ||
1020                         (rsi->allowedModes & SFRM_ValuePerCall) == 0 ||
1021                         (rsi->allowedModes & SFRM_Materialize) == 0)
1022                         ereport(ERROR,
1023                                         (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1024                                          errmsg("set-valued function called in context that cannot accept a set")));
1025                 randomAccess = rsi->allowedModes & SFRM_Materialize_Random;
1026                 lazyEvalOK = !(rsi->allowedModes & SFRM_Materialize_Preferred);
1027         }
1028         else
1029         {
1030                 randomAccess = false;
1031                 lazyEvalOK = true;
1032         }
1033
1034         /*
1035          * Initialize fcache (build plans) if first time through; or re-initialize
1036          * if the cache is stale.
1037          */
1038         fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
1039
1040         if (fcache != NULL)
1041         {
1042                 if (fcache->lxid != MyProc->lxid ||
1043                         !SubTransactionIsActive(fcache->subxid))
1044                 {
1045                         /* It's stale; unlink and delete */
1046                         fcinfo->flinfo->fn_extra = NULL;
1047                         MemoryContextDelete(fcache->fcontext);
1048                         fcache = NULL;
1049                 }
1050         }
1051
1052         if (fcache == NULL)
1053         {
1054                 init_sql_fcache(fcinfo->flinfo, PG_GET_COLLATION(), lazyEvalOK);
1055                 fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
1056         }
1057
1058         /*
1059          * Switch to context in which the fcache lives.  This ensures that our
1060          * tuplestore etc will have sufficient lifetime.  The sub-executor is
1061          * responsible for deleting per-tuple information.  (XXX in the case of a
1062          * long-lived FmgrInfo, this policy represents more memory leakage, but
1063          * it's not entirely clear where to keep stuff instead.)
1064          */
1065         oldcontext = MemoryContextSwitchTo(fcache->fcontext);
1066
1067         /*
1068          * Find first unfinished query in function, and note whether it's the
1069          * first query.
1070          */
1071         eslist = fcache->func_state;
1072         es = NULL;
1073         is_first = true;
1074         foreach(eslc, eslist)
1075         {
1076                 es = (execution_state *) lfirst(eslc);
1077
1078                 while (es && es->status == F_EXEC_DONE)
1079                 {
1080                         is_first = false;
1081                         es = es->next;
1082                 }
1083
1084                 if (es)
1085                         break;
1086         }
1087
1088         /*
1089          * Convert params to appropriate format if starting a fresh execution. (If
1090          * continuing execution, we can re-use prior params.)
1091          */
1092         if (is_first && es && es->status == F_EXEC_START)
1093                 postquel_sub_params(fcache, fcinfo);
1094
1095         /*
1096          * Build tuplestore to hold results, if we don't have one already. Note
1097          * it's in the query-lifespan context.
1098          */
1099         if (!fcache->tstore)
1100                 fcache->tstore = tuplestore_begin_heap(randomAccess, false, work_mem);
1101
1102         /*
1103          * Execute each command in the function one after another until we either
1104          * run out of commands or get a result row from a lazily-evaluated SELECT.
1105          *
1106          * Notes about snapshot management:
1107          *
1108          * In a read-only function, we just use the surrounding query's snapshot.
1109          *
1110          * In a non-read-only function, we rely on the fact that we'll never
1111          * suspend execution between queries of the function: the only reason to
1112          * suspend execution before completion is if we are returning a row from a
1113          * lazily-evaluated SELECT.  So, when first entering this loop, we'll
1114          * either start a new query (and push a fresh snapshot) or re-establish
1115          * the active snapshot from the existing query descriptor.  If we need to
1116          * start a new query in a subsequent execution of the loop, either we need
1117          * a fresh snapshot (and pushed_snapshot is false) or the existing
1118          * snapshot is on the active stack and we can just bump its command ID.
1119          */
1120         pushed_snapshot = false;
1121         while (es)
1122         {
1123                 bool            completed;
1124
1125                 if (es->status == F_EXEC_START)
1126                 {
1127                         /*
1128                          * If not read-only, be sure to advance the command counter for
1129                          * each command, so that all work to date in this transaction is
1130                          * visible.  Take a new snapshot if we don't have one yet,
1131                          * otherwise just bump the command ID in the existing snapshot.
1132                          */
1133                         if (!fcache->readonly_func)
1134                         {
1135                                 CommandCounterIncrement();
1136                                 if (!pushed_snapshot)
1137                                 {
1138                                         PushActiveSnapshot(GetTransactionSnapshot());
1139                                         pushed_snapshot = true;
1140                                 }
1141                                 else
1142                                         UpdateActiveSnapshotCommandId();
1143                         }
1144
1145                         postquel_start(es, fcache);
1146                 }
1147                 else if (!fcache->readonly_func && !pushed_snapshot)
1148                 {
1149                         /* Re-establish active snapshot when re-entering function */
1150                         PushActiveSnapshot(es->qd->snapshot);
1151                         pushed_snapshot = true;
1152                 }
1153
1154                 completed = postquel_getnext(es, fcache);
1155
1156                 /*
1157                  * If we ran the command to completion, we can shut it down now. Any
1158                  * row(s) we need to return are safely stashed in the tuplestore, and
1159                  * we want to be sure that, for example, AFTER triggers get fired
1160                  * before we return anything.  Also, if the function doesn't return
1161                  * set, we can shut it down anyway because it must be a SELECT and we
1162                  * don't care about fetching any more result rows.
1163                  */
1164                 if (completed || !fcache->returnsSet)
1165                         postquel_end(es);
1166
1167                 /*
1168                  * Break from loop if we didn't shut down (implying we got a
1169                  * lazily-evaluated row).  Otherwise we'll press on till the whole
1170                  * function is done, relying on the tuplestore to keep hold of the
1171                  * data to eventually be returned.  This is necessary since an
1172                  * INSERT/UPDATE/DELETE RETURNING that sets the result might be
1173                  * followed by additional rule-inserted commands, and we want to
1174                  * finish doing all those commands before we return anything.
1175                  */
1176                 if (es->status != F_EXEC_DONE)
1177                         break;
1178
1179                 /*
1180                  * Advance to next execution_state, which might be in the next list.
1181                  */
1182                 es = es->next;
1183                 while (!es)
1184                 {
1185                         eslc = lnext(eslc);
1186                         if (!eslc)
1187                                 break;                  /* end of function */
1188
1189                         es = (execution_state *) lfirst(eslc);
1190
1191                         /*
1192                          * Flush the current snapshot so that we will take a new one for
1193                          * the new query list.  This ensures that new snaps are taken at
1194                          * original-query boundaries, matching the behavior of interactive
1195                          * execution.
1196                          */
1197                         if (pushed_snapshot)
1198                         {
1199                                 PopActiveSnapshot();
1200                                 pushed_snapshot = false;
1201                         }
1202                 }
1203         }
1204
1205         /*
1206          * The tuplestore now contains whatever row(s) we are supposed to return.
1207          */
1208         if (fcache->returnsSet)
1209         {
1210                 ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
1211
1212                 if (es)
1213                 {
1214                         /*
1215                          * If we stopped short of being done, we must have a lazy-eval
1216                          * row.
1217                          */
1218                         Assert(es->lazyEval);
1219                         /* Re-use the junkfilter's output slot to fetch back the tuple */
1220                         Assert(fcache->junkFilter);
1221                         slot = fcache->junkFilter->jf_resultSlot;
1222                         if (!tuplestore_gettupleslot(fcache->tstore, true, false, slot))
1223                                 elog(ERROR, "failed to fetch lazy-eval tuple");
1224                         /* Extract the result as a datum, and copy out from the slot */
1225                         result = postquel_get_single_result(slot, fcinfo,
1226                                                                                                 fcache, oldcontext);
1227                         /* Clear the tuplestore, but keep it for next time */
1228                         /* NB: this might delete the slot's content, but we don't care */
1229                         tuplestore_clear(fcache->tstore);
1230
1231                         /*
1232                          * Let caller know we're not finished.
1233                          */
1234                         rsi->isDone = ExprMultipleResult;
1235
1236                         /*
1237                          * Ensure we will get shut down cleanly if the exprcontext is not
1238                          * run to completion.
1239                          */
1240                         if (!fcache->shutdown_reg)
1241                         {
1242                                 RegisterExprContextCallback(rsi->econtext,
1243                                                                                         ShutdownSQLFunction,
1244                                                                                         PointerGetDatum(fcache));
1245                                 fcache->shutdown_reg = true;
1246                         }
1247                 }
1248                 else if (fcache->lazyEval)
1249                 {
1250                         /*
1251                          * We are done with a lazy evaluation.  Clean up.
1252                          */
1253                         tuplestore_clear(fcache->tstore);
1254
1255                         /*
1256                          * Let caller know we're finished.
1257                          */
1258                         rsi->isDone = ExprEndResult;
1259
1260                         fcinfo->isnull = true;
1261                         result = (Datum) 0;
1262
1263                         /* Deregister shutdown callback, if we made one */
1264                         if (fcache->shutdown_reg)
1265                         {
1266                                 UnregisterExprContextCallback(rsi->econtext,
1267                                                                                           ShutdownSQLFunction,
1268                                                                                           PointerGetDatum(fcache));
1269                                 fcache->shutdown_reg = false;
1270                         }
1271                 }
1272                 else
1273                 {
1274                         /*
1275                          * We are done with a non-lazy evaluation.  Return whatever is in
1276                          * the tuplestore.  (It is now caller's responsibility to free the
1277                          * tuplestore when done.)
1278                          */
1279                         rsi->returnMode = SFRM_Materialize;
1280                         rsi->setResult = fcache->tstore;
1281                         fcache->tstore = NULL;
1282                         /* must copy desc because execSRF.c will free it */
1283                         if (fcache->junkFilter)
1284                                 rsi->setDesc = CreateTupleDescCopy(fcache->junkFilter->jf_cleanTupType);
1285
1286                         fcinfo->isnull = true;
1287                         result = (Datum) 0;
1288
1289                         /* Deregister shutdown callback, if we made one */
1290                         if (fcache->shutdown_reg)
1291                         {
1292                                 UnregisterExprContextCallback(rsi->econtext,
1293                                                                                           ShutdownSQLFunction,
1294                                                                                           PointerGetDatum(fcache));
1295                                 fcache->shutdown_reg = false;
1296                         }
1297                 }
1298         }
1299         else
1300         {
1301                 /*
1302                  * Non-set function.  If we got a row, return it; else return NULL.
1303                  */
1304                 if (fcache->junkFilter)
1305                 {
1306                         /* Re-use the junkfilter's output slot to fetch back the tuple */
1307                         slot = fcache->junkFilter->jf_resultSlot;
1308                         if (tuplestore_gettupleslot(fcache->tstore, true, false, slot))
1309                                 result = postquel_get_single_result(slot, fcinfo,
1310                                                                                                         fcache, oldcontext);
1311                         else
1312                         {
1313                                 fcinfo->isnull = true;
1314                                 result = (Datum) 0;
1315                         }
1316                 }
1317                 else
1318                 {
1319                         /* Should only get here for VOID functions */
1320                         Assert(fcache->rettype == VOIDOID);
1321                         fcinfo->isnull = true;
1322                         result = (Datum) 0;
1323                 }
1324
1325                 /* Clear the tuplestore, but keep it for next time */
1326                 tuplestore_clear(fcache->tstore);
1327         }
1328
1329         /* Pop snapshot if we have pushed one */
1330         if (pushed_snapshot)
1331                 PopActiveSnapshot();
1332
1333         /*
1334          * If we've gone through every command in the function, we are done. Reset
1335          * the execution states to start over again on next call.
1336          */
1337         if (es == NULL)
1338         {
1339                 foreach(eslc, fcache->func_state)
1340                 {
1341                         es = (execution_state *) lfirst(eslc);
1342                         while (es)
1343                         {
1344                                 es->status = F_EXEC_START;
1345                                 es = es->next;
1346                         }
1347                 }
1348         }
1349
1350         error_context_stack = sqlerrcontext.previous;
1351
1352         MemoryContextSwitchTo(oldcontext);
1353
1354         return result;
1355 }
1356
1357
1358 /*
1359  * error context callback to let us supply a call-stack traceback
1360  */
1361 static void
1362 sql_exec_error_callback(void *arg)
1363 {
1364         FmgrInfo   *flinfo = (FmgrInfo *) arg;
1365         SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) flinfo->fn_extra;
1366         int                     syntaxerrposition;
1367
1368         /*
1369          * We can do nothing useful if init_sql_fcache() didn't get as far as
1370          * saving the function name
1371          */
1372         if (fcache == NULL || fcache->fname == NULL)
1373                 return;
1374
1375         /*
1376          * If there is a syntax error position, convert to internal syntax error
1377          */
1378         syntaxerrposition = geterrposition();
1379         if (syntaxerrposition > 0 && fcache->src != NULL)
1380         {
1381                 errposition(0);
1382                 internalerrposition(syntaxerrposition);
1383                 internalerrquery(fcache->src);
1384         }
1385
1386         /*
1387          * Try to determine where in the function we failed.  If there is a query
1388          * with non-null QueryDesc, finger it.  (We check this rather than looking
1389          * for F_EXEC_RUN state, so that errors during ExecutorStart or
1390          * ExecutorEnd are blamed on the appropriate query; see postquel_start and
1391          * postquel_end.)
1392          */
1393         if (fcache->func_state)
1394         {
1395                 execution_state *es;
1396                 int                     query_num;
1397                 ListCell   *lc;
1398
1399                 es = NULL;
1400                 query_num = 1;
1401                 foreach(lc, fcache->func_state)
1402                 {
1403                         es = (execution_state *) lfirst(lc);
1404                         while (es)
1405                         {
1406                                 if (es->qd)
1407                                 {
1408                                         errcontext("SQL function \"%s\" statement %d",
1409                                                            fcache->fname, query_num);
1410                                         break;
1411                                 }
1412                                 es = es->next;
1413                         }
1414                         if (es)
1415                                 break;
1416                         query_num++;
1417                 }
1418                 if (es == NULL)
1419                 {
1420                         /*
1421                          * couldn't identify a running query; might be function entry,
1422                          * function exit, or between queries.
1423                          */
1424                         errcontext("SQL function \"%s\"", fcache->fname);
1425                 }
1426         }
1427         else
1428         {
1429                 /*
1430                  * Assume we failed during init_sql_fcache().  (It's possible that the
1431                  * function actually has an empty body, but in that case we may as
1432                  * well report all errors as being "during startup".)
1433                  */
1434                 errcontext("SQL function \"%s\" during startup", fcache->fname);
1435         }
1436 }
1437
1438
1439 /*
1440  * callback function in case a function-returning-set needs to be shut down
1441  * before it has been run to completion
1442  */
1443 static void
1444 ShutdownSQLFunction(Datum arg)
1445 {
1446         SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) DatumGetPointer(arg);
1447         execution_state *es;
1448         ListCell   *lc;
1449
1450         foreach(lc, fcache->func_state)
1451         {
1452                 es = (execution_state *) lfirst(lc);
1453                 while (es)
1454                 {
1455                         /* Shut down anything still running */
1456                         if (es->status == F_EXEC_RUN)
1457                         {
1458                                 /* Re-establish active snapshot for any called functions */
1459                                 if (!fcache->readonly_func)
1460                                         PushActiveSnapshot(es->qd->snapshot);
1461
1462                                 postquel_end(es);
1463
1464                                 if (!fcache->readonly_func)
1465                                         PopActiveSnapshot();
1466                         }
1467
1468                         /* Reset states to START in case we're called again */
1469                         es->status = F_EXEC_START;
1470                         es = es->next;
1471                 }
1472         }
1473
1474         /* Release tuplestore if we have one */
1475         if (fcache->tstore)
1476                 tuplestore_end(fcache->tstore);
1477         fcache->tstore = NULL;
1478
1479         /* execUtils will deregister the callback... */
1480         fcache->shutdown_reg = false;
1481 }
1482
1483
1484 /*
1485  * check_sql_fn_retval() -- check return value of a list of sql parse trees.
1486  *
1487  * The return value of a sql function is the value returned by the last
1488  * canSetTag query in the function.  We do some ad-hoc type checking here
1489  * to be sure that the user is returning the type he claims.  There are
1490  * also a couple of strange-looking features to assist callers in dealing
1491  * with allowed special cases, such as binary-compatible result types.
1492  *
1493  * For a polymorphic function the passed rettype must be the actual resolved
1494  * output type of the function; we should never see a polymorphic pseudotype
1495  * such as ANYELEMENT as rettype.  (This means we can't check the type during
1496  * function definition of a polymorphic function.)
1497  *
1498  * This function returns true if the sql function returns the entire tuple
1499  * result of its final statement, or false if it returns just the first column
1500  * result of that statement.  It throws an error if the final statement doesn't
1501  * return the right type at all.
1502  *
1503  * Note that because we allow "SELECT rowtype_expression", the result can be
1504  * false even when the declared function return type is a rowtype.
1505  *
1506  * If modifyTargetList isn't NULL, the function will modify the final
1507  * statement's targetlist in two cases:
1508  * (1) if the tlist returns values that are binary-coercible to the expected
1509  * type rather than being exactly the expected type.  RelabelType nodes will
1510  * be inserted to make the result types match exactly.
1511  * (2) if there are dropped columns in the declared result rowtype.  NULL
1512  * output columns will be inserted in the tlist to match them.
1513  * (Obviously the caller must pass a parsetree that is okay to modify when
1514  * using this flag.)  Note that this flag does not affect whether the tlist is
1515  * considered to be a legal match to the result type, only how we react to
1516  * allowed not-exact-match cases.  *modifyTargetList will be set true iff
1517  * we had to make any "dangerous" changes that could modify the semantics of
1518  * the statement.  If it is set true, the caller should not use the modified
1519  * statement, but for simplicity we apply the changes anyway.
1520  *
1521  * If junkFilter isn't NULL, then *junkFilter is set to a JunkFilter defined
1522  * to convert the function's tuple result to the correct output tuple type.
1523  * Exception: if the function is defined to return VOID then *junkFilter is
1524  * set to NULL.
1525  */
1526 bool
1527 check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
1528                                         bool *modifyTargetList,
1529                                         JunkFilter **junkFilter)
1530 {
1531         Query      *parse;
1532         List      **tlist_ptr;
1533         List       *tlist;
1534         int                     tlistlen;
1535         char            fn_typtype;
1536         Oid                     restype;
1537         ListCell   *lc;
1538
1539         AssertArg(!IsPolymorphicType(rettype));
1540
1541         if (modifyTargetList)
1542                 *modifyTargetList = false;              /* initialize for no change */
1543         if (junkFilter)
1544                 *junkFilter = NULL;             /* initialize in case of VOID result */
1545
1546         /*
1547          * Find the last canSetTag query in the list.  This isn't necessarily the
1548          * last parsetree, because rule rewriting can insert queries after what
1549          * the user wrote.
1550          */
1551         parse = NULL;
1552         foreach(lc, queryTreeList)
1553         {
1554                 Query      *q = castNode(Query, lfirst(lc));
1555
1556                 if (q->canSetTag)
1557                         parse = q;
1558         }
1559
1560         /*
1561          * If it's a plain SELECT, it returns whatever the targetlist says.
1562          * Otherwise, if it's INSERT/UPDATE/DELETE with RETURNING, it returns
1563          * that. Otherwise, the function return type must be VOID.
1564          *
1565          * Note: eventually replace this test with QueryReturnsTuples?  We'd need
1566          * a more general method of determining the output type, though.  Also, it
1567          * seems too dangerous to consider FETCH or EXECUTE as returning a
1568          * determinable rowtype, since they depend on relatively short-lived
1569          * entities.
1570          */
1571         if (parse &&
1572                 parse->commandType == CMD_SELECT)
1573         {
1574                 tlist_ptr = &parse->targetList;
1575                 tlist = parse->targetList;
1576         }
1577         else if (parse &&
1578                          (parse->commandType == CMD_INSERT ||
1579                           parse->commandType == CMD_UPDATE ||
1580                           parse->commandType == CMD_DELETE) &&
1581                          parse->returningList)
1582         {
1583                 tlist_ptr = &parse->returningList;
1584                 tlist = parse->returningList;
1585         }
1586         else
1587         {
1588                 /* Empty function body, or last statement is a utility command */
1589                 if (rettype != VOIDOID)
1590                         ereport(ERROR,
1591                                         (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1592                          errmsg("return type mismatch in function declared to return %s",
1593                                         format_type_be(rettype)),
1594                                          errdetail("Function's final statement must be SELECT or INSERT/UPDATE/DELETE RETURNING.")));
1595                 return false;
1596         }
1597
1598         /*
1599          * OK, check that the targetlist returns something matching the declared
1600          * type.  (We used to insist that the declared type not be VOID in this
1601          * case, but that makes it hard to write a void function that exits after
1602          * calling another void function.  Instead, we insist that the tlist
1603          * return void ... so void is treated as if it were a scalar type below.)
1604          */
1605
1606         /*
1607          * Count the non-junk entries in the result targetlist.
1608          */
1609         tlistlen = ExecCleanTargetListLength(tlist);
1610
1611         fn_typtype = get_typtype(rettype);
1612
1613         if (fn_typtype == TYPTYPE_BASE ||
1614                 fn_typtype == TYPTYPE_DOMAIN ||
1615                 fn_typtype == TYPTYPE_ENUM ||
1616                 fn_typtype == TYPTYPE_RANGE ||
1617                 rettype == VOIDOID)
1618         {
1619                 /*
1620                  * For scalar-type returns, the target list must have exactly one
1621                  * non-junk entry, and its type must agree with what the user
1622                  * declared; except we allow binary-compatible types too.
1623                  */
1624                 TargetEntry *tle;
1625
1626                 if (tlistlen != 1)
1627                         ereport(ERROR,
1628                                         (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1629                          errmsg("return type mismatch in function declared to return %s",
1630                                         format_type_be(rettype)),
1631                           errdetail("Final statement must return exactly one column.")));
1632
1633                 /* We assume here that non-junk TLEs must come first in tlists */
1634                 tle = (TargetEntry *) linitial(tlist);
1635                 Assert(!tle->resjunk);
1636
1637                 restype = exprType((Node *) tle->expr);
1638                 if (!IsBinaryCoercible(restype, rettype))
1639                         ereport(ERROR,
1640                                         (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1641                          errmsg("return type mismatch in function declared to return %s",
1642                                         format_type_be(rettype)),
1643                                          errdetail("Actual return type is %s.",
1644                                                            format_type_be(restype))));
1645                 if (modifyTargetList && restype != rettype)
1646                 {
1647                         tle->expr = (Expr *) makeRelabelType(tle->expr,
1648                                                                                                  rettype,
1649                                                                                                  -1,
1650                                                                                                  get_typcollation(rettype),
1651                                                                                                  COERCE_IMPLICIT_CAST);
1652                         /* Relabel is dangerous if TLE is a sort/group or setop column */
1653                         if (tle->ressortgroupref != 0 || parse->setOperations)
1654                                 *modifyTargetList = true;
1655                 }
1656
1657                 /* Set up junk filter if needed */
1658                 if (junkFilter)
1659                         *junkFilter = ExecInitJunkFilter(tlist, false, NULL);
1660         }
1661         else if (fn_typtype == TYPTYPE_COMPOSITE || rettype == RECORDOID)
1662         {
1663                 /* Returns a rowtype */
1664                 TupleDesc       tupdesc;
1665                 int                     tupnatts;       /* physical number of columns in tuple */
1666                 int                     tuplogcols; /* # of nondeleted columns in tuple */
1667                 int                     colindex;       /* physical column index */
1668                 List       *newtlist;   /* new non-junk tlist entries */
1669                 List       *junkattrs;  /* new junk tlist entries */
1670
1671                 /*
1672                  * If the target list is of length 1, and the type of the varnode in
1673                  * the target list matches the declared return type, this is okay.
1674                  * This can happen, for example, where the body of the function is
1675                  * 'SELECT func2()', where func2 has the same composite return type as
1676                  * the function that's calling it.
1677                  *
1678                  * XXX Note that if rettype is RECORD, the IsBinaryCoercible check
1679                  * will succeed for any composite restype.  For the moment we rely on
1680                  * runtime type checking to catch any discrepancy, but it'd be nice to
1681                  * do better at parse time.
1682                  */
1683                 if (tlistlen == 1)
1684                 {
1685                         TargetEntry *tle = (TargetEntry *) linitial(tlist);
1686
1687                         Assert(!tle->resjunk);
1688                         restype = exprType((Node *) tle->expr);
1689                         if (IsBinaryCoercible(restype, rettype))
1690                         {
1691                                 if (modifyTargetList && restype != rettype)
1692                                 {
1693                                         tle->expr = (Expr *) makeRelabelType(tle->expr,
1694                                                                                                                  rettype,
1695                                                                                                                  -1,
1696                                                                                                    get_typcollation(rettype),
1697                                                                                                            COERCE_IMPLICIT_CAST);
1698                                         /* Relabel is dangerous if sort/group or setop column */
1699                                         if (tle->ressortgroupref != 0 || parse->setOperations)
1700                                                 *modifyTargetList = true;
1701                                 }
1702                                 /* Set up junk filter if needed */
1703                                 if (junkFilter)
1704                                         *junkFilter = ExecInitJunkFilter(tlist, false, NULL);
1705                                 return false;   /* NOT returning whole tuple */
1706                         }
1707                 }
1708
1709                 /* Is the rowtype fixed, or determined only at runtime? */
1710                 if (get_func_result_type(func_id, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
1711                 {
1712                         /*
1713                          * Assume we are returning the whole tuple. Crosschecking against
1714                          * what the caller expects will happen at runtime.
1715                          */
1716                         if (junkFilter)
1717                                 *junkFilter = ExecInitJunkFilter(tlist, false, NULL);
1718                         return true;
1719                 }
1720                 Assert(tupdesc);
1721
1722                 /*
1723                  * Verify that the targetlist matches the return tuple type. We scan
1724                  * the non-deleted attributes to ensure that they match the datatypes
1725                  * of the non-resjunk columns.  For deleted attributes, insert NULL
1726                  * result columns if the caller asked for that.
1727                  */
1728                 tupnatts = tupdesc->natts;
1729                 tuplogcols = 0;                 /* we'll count nondeleted cols as we go */
1730                 colindex = 0;
1731                 newtlist = NIL;                 /* these are only used if modifyTargetList */
1732                 junkattrs = NIL;
1733
1734                 foreach(lc, tlist)
1735                 {
1736                         TargetEntry *tle = (TargetEntry *) lfirst(lc);
1737                         Form_pg_attribute attr;
1738                         Oid                     tletype;
1739                         Oid                     atttype;
1740
1741                         if (tle->resjunk)
1742                         {
1743                                 if (modifyTargetList)
1744                                         junkattrs = lappend(junkattrs, tle);
1745                                 continue;
1746                         }
1747
1748                         do
1749                         {
1750                                 colindex++;
1751                                 if (colindex > tupnatts)
1752                                         ereport(ERROR,
1753                                                         (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1754                                                          errmsg("return type mismatch in function declared to return %s",
1755                                                                         format_type_be(rettype)),
1756                                         errdetail("Final statement returns too many columns.")));
1757                                 attr = tupdesc->attrs[colindex - 1];
1758                                 if (attr->attisdropped && modifyTargetList)
1759                                 {
1760                                         Expr       *null_expr;
1761
1762                                         /* The type of the null we insert isn't important */
1763                                         null_expr = (Expr *) makeConst(INT4OID,
1764                                                                                                    -1,
1765                                                                                                    InvalidOid,
1766                                                                                                    sizeof(int32),
1767                                                                                                    (Datum) 0,
1768                                                                                                    true,                /* isnull */
1769                                                                                                    true /* byval */ );
1770                                         newtlist = lappend(newtlist,
1771                                                                            makeTargetEntry(null_expr,
1772                                                                                                            colindex,
1773                                                                                                            NULL,
1774                                                                                                            false));
1775                                         /* NULL insertion is dangerous in a setop */
1776                                         if (parse->setOperations)
1777                                                 *modifyTargetList = true;
1778                                 }
1779                         } while (attr->attisdropped);
1780                         tuplogcols++;
1781
1782                         tletype = exprType((Node *) tle->expr);
1783                         atttype = attr->atttypid;
1784                         if (!IsBinaryCoercible(tletype, atttype))
1785                                 ereport(ERROR,
1786                                                 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1787                                                  errmsg("return type mismatch in function declared to return %s",
1788                                                                 format_type_be(rettype)),
1789                                                  errdetail("Final statement returns %s instead of %s at column %d.",
1790                                                                    format_type_be(tletype),
1791                                                                    format_type_be(atttype),
1792                                                                    tuplogcols)));
1793                         if (modifyTargetList)
1794                         {
1795                                 if (tletype != atttype)
1796                                 {
1797                                         tle->expr = (Expr *) makeRelabelType(tle->expr,
1798                                                                                                                  atttype,
1799                                                                                                                  -1,
1800                                                                                                    get_typcollation(atttype),
1801                                                                                                            COERCE_IMPLICIT_CAST);
1802                                         /* Relabel is dangerous if sort/group or setop column */
1803                                         if (tle->ressortgroupref != 0 || parse->setOperations)
1804                                                 *modifyTargetList = true;
1805                                 }
1806                                 tle->resno = colindex;
1807                                 newtlist = lappend(newtlist, tle);
1808                         }
1809                 }
1810
1811                 /* remaining columns in tupdesc had better all be dropped */
1812                 for (colindex++; colindex <= tupnatts; colindex++)
1813                 {
1814                         if (!tupdesc->attrs[colindex - 1]->attisdropped)
1815                                 ereport(ERROR,
1816                                                 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1817                                                  errmsg("return type mismatch in function declared to return %s",
1818                                                                 format_type_be(rettype)),
1819                                          errdetail("Final statement returns too few columns.")));
1820                         if (modifyTargetList)
1821                         {
1822                                 Expr       *null_expr;
1823
1824                                 /* The type of the null we insert isn't important */
1825                                 null_expr = (Expr *) makeConst(INT4OID,
1826                                                                                            -1,
1827                                                                                            InvalidOid,
1828                                                                                            sizeof(int32),
1829                                                                                            (Datum) 0,
1830                                                                                            true,        /* isnull */
1831                                                                                            true /* byval */ );
1832                                 newtlist = lappend(newtlist,
1833                                                                    makeTargetEntry(null_expr,
1834                                                                                                    colindex,
1835                                                                                                    NULL,
1836                                                                                                    false));
1837                                 /* NULL insertion is dangerous in a setop */
1838                                 if (parse->setOperations)
1839                                         *modifyTargetList = true;
1840                         }
1841                 }
1842
1843                 if (modifyTargetList)
1844                 {
1845                         /* ensure resjunk columns are numbered correctly */
1846                         foreach(lc, junkattrs)
1847                         {
1848                                 TargetEntry *tle = (TargetEntry *) lfirst(lc);
1849
1850                                 tle->resno = colindex++;
1851                         }
1852                         /* replace the tlist with the modified one */
1853                         *tlist_ptr = list_concat(newtlist, junkattrs);
1854                 }
1855
1856                 /* Set up junk filter if needed */
1857                 if (junkFilter)
1858                         *junkFilter = ExecInitJunkFilterConversion(tlist,
1859                                                                                                 CreateTupleDescCopy(tupdesc),
1860                                                                                                            NULL);
1861
1862                 /* Report that we are returning entire tuple result */
1863                 return true;
1864         }
1865         else
1866                 ereport(ERROR,
1867                                 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1868                                  errmsg("return type %s is not supported for SQL functions",
1869                                                 format_type_be(rettype))));
1870
1871         return false;
1872 }
1873
1874
1875 /*
1876  * CreateSQLFunctionDestReceiver -- create a suitable DestReceiver object
1877  */
1878 DestReceiver *
1879 CreateSQLFunctionDestReceiver(void)
1880 {
1881         DR_sqlfunction *self = (DR_sqlfunction *) palloc0(sizeof(DR_sqlfunction));
1882
1883         self->pub.receiveSlot = sqlfunction_receive;
1884         self->pub.rStartup = sqlfunction_startup;
1885         self->pub.rShutdown = sqlfunction_shutdown;
1886         self->pub.rDestroy = sqlfunction_destroy;
1887         self->pub.mydest = DestSQLFunction;
1888
1889         /* private fields will be set by postquel_start */
1890
1891         return (DestReceiver *) self;
1892 }
1893
1894 /*
1895  * sqlfunction_startup --- executor startup
1896  */
1897 static void
1898 sqlfunction_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
1899 {
1900         /* no-op */
1901 }
1902
1903 /*
1904  * sqlfunction_receive --- receive one tuple
1905  */
1906 static bool
1907 sqlfunction_receive(TupleTableSlot *slot, DestReceiver *self)
1908 {
1909         DR_sqlfunction *myState = (DR_sqlfunction *) self;
1910
1911         /* Filter tuple as needed */
1912         slot = ExecFilterJunk(myState->filter, slot);
1913
1914         /* Store the filtered tuple into the tuplestore */
1915         tuplestore_puttupleslot(myState->tstore, slot);
1916
1917         return true;
1918 }
1919
1920 /*
1921  * sqlfunction_shutdown --- executor end
1922  */
1923 static void
1924 sqlfunction_shutdown(DestReceiver *self)
1925 {
1926         /* no-op */
1927 }
1928
1929 /*
1930  * sqlfunction_destroy --- release DestReceiver object
1931  */
1932 static void
1933 sqlfunction_destroy(DestReceiver *self)
1934 {
1935         pfree(self);
1936 }