pltcl.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

		/* Must reset elog.c's state */
		MemoryContextSwitchTo(oldcontext);
		edata = CopyErrorData();
		FlushErrorState();

		/* Pass the error message to Tcl */
		Tcl_SetResult(interp, edata->message, TCL_VOLATILE);
		FreeErrorData(edata);

		return TCL_ERROR;
	}
	PG_END_TRY();

	return TCL_OK;
}


/**********************************************************************
 * pltcl_quote()	- quote literal strings that are to
 *			  be used in SPI_execute query strings
 **********************************************************************/
static int
pltcl_quote(ClientData cdata, Tcl_Interp *interp,
			int argc, CONST84 char *argv[])
{
	char	   *tmp;
	const char *cp1;
	char	   *cp2;

	/************************************************************
	 * Check call syntax
	 ************************************************************/
	if (argc != 2)
	{
		Tcl_SetResult(interp, "syntax error - 'quote string'", TCL_VOLATILE);
		return TCL_ERROR;
	}

	/************************************************************
	 * Allocate space for the maximum the string can
	 * grow to and initialize pointers
	 ************************************************************/
	tmp = palloc(strlen(argv[1]) * 2 + 1);
	cp1 = argv[1];
	cp2 = tmp;

	/************************************************************
	 * Walk through string and double every quote and backslash
	 ************************************************************/
	while (*cp1)
	{
		if (*cp1 == '\'')
			*cp2++ = '\'';
		else
		{
			if (*cp1 == '\\')
				*cp2++ = '\\';
		}
		*cp2++ = *cp1++;
	}

	/************************************************************
	 * Terminate the string and set it as result
	 ************************************************************/
	*cp2 = '\0';
	Tcl_SetResult(interp, tmp, TCL_VOLATILE);
	pfree(tmp);
	return TCL_OK;
}


/**********************************************************************
 * pltcl_argisnull()	- determine if a specific argument is NULL
 **********************************************************************/
static int
pltcl_argisnull(ClientData cdata, Tcl_Interp *interp,
				int argc, CONST84 char *argv[])
{
	int			argno;
	FunctionCallInfo fcinfo = pltcl_current_fcinfo;

	/************************************************************
	 * Check call syntax
	 ************************************************************/
	if (argc != 2)
	{
		Tcl_SetResult(interp, "syntax error - 'argisnull argno'", TCL_VOLATILE);
		return TCL_ERROR;
	}

	/************************************************************
	 * Check that we're called as a normal function
	 ************************************************************/
	if (fcinfo == NULL)
	{
		Tcl_SetResult(interp, "argisnull cannot be used in triggers",
					  TCL_VOLATILE);
		return TCL_ERROR;
	}

	/************************************************************
	 * Get the argument number
	 ************************************************************/
	if (Tcl_GetInt(interp, argv[1], &argno) != TCL_OK)
		return TCL_ERROR;

	/************************************************************
	 * Check that the argno is valid
	 ************************************************************/
	argno--;
	if (argno < 0 || argno >= fcinfo->nargs)
	{
		Tcl_SetResult(interp, "argno out of range", TCL_VOLATILE);
		return TCL_ERROR;
	}

	/************************************************************
	 * Get the requested NULL state
	 ************************************************************/
	if (PG_ARGISNULL(argno))
		Tcl_SetResult(interp, "1", TCL_VOLATILE);
	else
		Tcl_SetResult(interp, "0", TCL_VOLATILE);

	return TCL_OK;
}


/**********************************************************************
 * pltcl_returnnull()	- Cause a NULL return from a function
 **********************************************************************/
static int
pltcl_returnnull(ClientData cdata, Tcl_Interp *interp,
				 int argc, CONST84 char *argv[])
{
	FunctionCallInfo fcinfo = pltcl_current_fcinfo;

	/************************************************************
	 * Check call syntax
	 ************************************************************/
	if (argc != 1)
	{
		Tcl_SetResult(interp, "syntax error - 'return_null'", TCL_VOLATILE);
		return TCL_ERROR;
	}

	/************************************************************
	 * Check that we're called as a normal function
	 ************************************************************/
	if (fcinfo == NULL)
	{
		Tcl_SetResult(interp, "return_null cannot be used in triggers",
					  TCL_VOLATILE);
		return TCL_ERROR;
	}

	/************************************************************
	 * Set the NULL return flag and cause Tcl to return from the
	 * procedure.
	 ************************************************************/
	fcinfo->isnull = true;

	return TCL_RETURN;
}


/*----------
 * Support for running SPI operations inside subtransactions
 *
 * Intended usage pattern is:
 *
 *	MemoryContext oldcontext = CurrentMemoryContext;
 *	ResourceOwner oldowner = CurrentResourceOwner;
 *
 *	...
 *	pltcl_subtrans_begin(oldcontext, oldowner);
 *	PG_TRY();
 *	{
 *		do something risky;
 *		pltcl_subtrans_commit(oldcontext, oldowner);
 *	}
 *	PG_CATCH();
 *	{
 *		pltcl_subtrans_abort(interp, oldcontext, oldowner);
 *		return TCL_ERROR;
 *	}
 *	PG_END_TRY();
 *	return TCL_OK;
 *----------
 */
static void
pltcl_subtrans_begin(MemoryContext oldcontext, ResourceOwner oldowner)
{
	BeginInternalSubTransaction(NULL);

	/* Want to run inside function's memory context */
	MemoryContextSwitchTo(oldcontext);
}

static void
pltcl_subtrans_commit(MemoryContext oldcontext, ResourceOwner oldowner)
{
	/* Commit the inner transaction, return to outer xact context */
	ReleaseCurrentSubTransaction();
	MemoryContextSwitchTo(oldcontext);
	CurrentResourceOwner = oldowner;

	/*
	 * AtEOSubXact_SPI() should not have popped any SPI context, but just in
	 * case it did, make sure we remain connected.
	 */
	SPI_restore_connection();
}

static void
pltcl_subtrans_abort(Tcl_Interp *interp,
					 MemoryContext oldcontext, ResourceOwner oldowner)
{
	ErrorData  *edata;

	/* Save error info */
	MemoryContextSwitchTo(oldcontext);
	edata = CopyErrorData();
	FlushErrorState();

	/* Abort the inner transaction */
	RollbackAndReleaseCurrentSubTransaction();
	MemoryContextSwitchTo(oldcontext);
	CurrentResourceOwner = oldowner;

	/*
	 * If AtEOSubXact_SPI() popped any SPI context of the subxact, it will
	 * have left us in a disconnected state.  We need this hack to return to
	 * connected state.
	 */
	SPI_restore_connection();

	/* Pass the error message to Tcl */
	Tcl_SetResult(interp, edata->message, TCL_VOLATILE);
	FreeErrorData(edata);
}


/**********************************************************************
 * pltcl_SPI_execute()		- The builtin SPI_execute command
 *				  for the Tcl interpreter
 **********************************************************************/
static int
pltcl_SPI_execute(ClientData cdata, Tcl_Interp *interp,
				  int argc, CONST84 char *argv[])
{
	int			my_rc;
	int			spi_rc;
	int			query_idx;
	int			i;
	int			count = 0;
	CONST84 char *volatile arrayname = NULL;
	CONST84 char *volatile loop_body = NULL;
	MemoryContext oldcontext = CurrentMemoryContext;
	ResourceOwner oldowner = CurrentResourceOwner;

	char	   *usage = "syntax error - 'SPI_exec "
	"?-count n? "
	"?-array name? query ?loop body?";

	/************************************************************
	 * Check the call syntax and get the options
	 ************************************************************/
	if (argc < 2)
	{
		Tcl_SetResult(interp, usage, TCL_VOLATILE);
		return TCL_ERROR;
	}

	i = 1;
	while (i < argc)
	{
		if (strcmp(argv[i], "-array") == 0)
		{
			if (++i >= argc)
			{
				Tcl_SetResult(interp, usage, TCL_VOLATILE);
				return TCL_ERROR;
			}
			arrayname = argv[i++];
			continue;
		}

		if (strcmp(argv[i], "-count") == 0)
		{
			if (++i >= argc)
			{
				Tcl_SetResult(interp, usage, TCL_VOLATILE);
				return TCL_ERROR;
			}
			if (Tcl_GetInt(interp, argv[i++], &count) != TCL_OK)
				return TCL_ERROR;
			continue;
		}

		break;
	}

	query_idx = i;
	if (query_idx >= argc || query_idx + 2 < argc)
	{
		Tcl_SetResult(interp, usage, TCL_VOLATILE);
		return TCL_ERROR;
	}
	if (query_idx + 1 < argc)
		loop_body = argv[query_idx + 1];

	/************************************************************
	 * Execute the query inside a sub-transaction, so we can cope with
	 * errors sanely
	 ************************************************************/

	pltcl_subtrans_begin(oldcontext, oldowner);

	PG_TRY();
	{
		UTF_BEGIN;
		spi_rc = SPI_execute(UTF_U2E(argv[query_idx]),
							 pltcl_current_prodesc->fn_readonly, count);
		UTF_END;

		my_rc = pltcl_process_SPI_result(interp,
										 arrayname,
										 loop_body,
										 spi_rc,
										 SPI_tuptable,
										 SPI_processed);

		pltcl_subtrans_commit(oldcontext, oldowner);
	}
	PG_CATCH();
	{
		pltcl_subtrans_abort(interp, oldcontext, oldowner);
		return TCL_ERROR;
	}
	PG_END_TRY();

	return my_rc;
}

/*
 * Process the result from SPI_execute or SPI_execute_plan
 *
 * Shared code between pltcl_SPI_execute and pltcl_SPI_execute_plan
 */
static int
pltcl_process_SPI_result(Tcl_Interp *interp,
						 CONST84 char *arrayname,
						 CONST84 char *loop_body,
						 int spi_rc,
						 SPITupleTable *tuptable,
						 int ntuples)
{
	int			my_rc = TCL_OK;
	char		buf[64];
	int			i;
	int			loop_rc;
	HeapTuple  *tuples;
	TupleDesc	tupdesc;

	switch (spi_rc)
	{
		case SPI_OK_UTILITY:
			Tcl_SetResult(interp, "0", TCL_VOLATILE);
			break;

		case SPI_OK_SELINTO:
		case SPI_OK_INSERT:
		case SPI_OK_DELETE:
		case SPI_OK_UPDATE:
			snprintf(buf, sizeof(buf), "%d", ntuples);
			Tcl_SetResult(interp, buf, TCL_VOLATILE);
			break;

		case SPI_OK_SELECT:

			/*
			 * Process the tuples we got
			 */
			tuples = tuptable->vals;
			tupdesc = tuptable->tupdesc;

			if (loop_body == NULL)
			{
				/*
				 * If there is no loop body given, just set the variables from
				 * the first tuple (if any)
				 */
				if (ntuples > 0)
					pltcl_set_tuple_values(interp, arrayname, 0,
										   tuples[0], tupdesc);
			}
			else
			{
				/*
				 * There is a loop body - process all tuples and evaluate the
				 * body on each
				 */
				for (i = 0; i < ntuples; i++)
				{
					pltcl_set_tuple_values(interp, arrayname, i,
										   tuples[i], tupdesc);

					loop_rc = Tcl_Eval(interp, loop_body);

					if (loop_rc == TCL_OK)
						continue;
					if (loop_rc == TCL_CONTINUE)
						continue;
					if (loop_rc == TCL_RETURN)
					{
						my_rc = TCL_RETURN;
						break;
					}
					if (loop_rc == TCL_BREAK)
						break;
					my_rc = TCL_ERROR;
					break;
				}
			}

			if (my_rc == TCL_OK)
			{
				snprintf(buf, sizeof(buf), "%d", ntuples);
				Tcl_SetResult(interp, buf, TCL_VOLATILE);
			}
			break;

		default:
			Tcl_AppendResult(interp, "pltcl: SPI_execute failed: ",
							 SPI_result_code_string(spi_rc), NULL);
			my_rc = TCL_ERROR;
			break;
	}