plpython.c

PostgreSQL7.4.6 for Linux

/**********************************************************************
 * plpython.c - python as a procedural language for PostgreSQL
 *
 * This software is copyright by Andrew Bosma
 * but is really shameless cribbed from pltcl.c by Jan Weick, and
 * plperl.c by Mark Hollomon.
 *
 * The author hereby grants permission to use, copy, modify,
 * distribute, and license this software and its documentation for any
 * purpose, provided that existing copyright notices are retained in
 * all copies and that this notice is included verbatim in any
 * distributions. No written agreement, license, or royalty fee is
 * required for any of the authorized uses.  Modifications to this
 * software may be copyrighted by their author and need not follow the
 * licensing terms described here, provided that the new terms are
 * clearly indicated on the first page of each file where they apply.
 *
 * IN NO EVENT SHALL THE AUTHOR OR DISTRIBUTORS BE LIABLE TO ANY PARTY
 * FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 * ARISING OUT OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, OR ANY
 * DERIVATIVES THEREOF, EVEN IF THE AUTHOR HAVE BEEN ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * THE AUTHOR AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND
 * NON-INFRINGEMENT.  THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS,
 * AND THE AUTHOR AND DISTRIBUTORS HAVE NO OBLIGATION TO PROVIDE
 * MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 *
 * IDENTIFICATION
 *	$Header: /cvsroot/pgsql/src/pl/plpython/plpython.c,v 1.41.2.1 2004/01/04 00:14:55 momjian Exp $
 *
 *********************************************************************
 */

#include "postgres.h"

/* system stuff
 */
#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <setjmp.h>

/* postgreSQL stuff
 */
#include "access/heapam.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "commands/trigger.h"
#include "executor/spi.h"
#include "fmgr.h"
#include "nodes/makefuncs.h"
#include "parser/parse_type.h"
#include "tcop/tcopprot.h"
#include "utils/syscache.h"

#include <Python.h>
#include <compile.h>
#include <eval.h>
#include "plpython.h"

/* convert Postgresql Datum or tuple into a PyObject.
 * input to Python.  Tuples are converted to dictionary
 * objects.
 */

typedef PyObject *(*PLyDatumToObFunc) (const char *);

typedef struct PLyDatumToOb
{
	PLyDatumToObFunc func;
	FmgrInfo	typfunc;
	Oid			typelem;
	bool		typbyval;
}	PLyDatumToOb;

typedef struct PLyTupleToOb
{
	PLyDatumToOb *atts;
	int			natts;
}	PLyTupleToOb;

typedef union PLyTypeInput
{
	PLyDatumToOb d;
	PLyTupleToOb r;
}	PLyTypeInput;

/* convert PyObject to a Postgresql Datum or tuple.
 * output from Python
 */
typedef struct PLyObToDatum
{
	FmgrInfo	typfunc;
	Oid			typelem;
	bool		typbyval;
}	PLyObToDatum;

typedef struct PLyObToTuple
{
	PLyObToDatum *atts;
	int			natts;
}	PLyObToTuple;

typedef union PLyTypeOutput
{
	PLyObToDatum d;
	PLyObToTuple r;
}	PLyTypeOutput;

/* all we need to move Postgresql data to Python objects,
 * and vis versa
 */
typedef struct PLyTypeInfo
{
	PLyTypeInput in;
	PLyTypeOutput out;
	int			is_rel;
}	PLyTypeInfo;


/* cached procedure data
 */
typedef struct PLyProcedure
{
	char	   *proname;		/* SQL name of procedure */
	char	   *pyname;			/* Python name of procedure */
	TransactionId fn_xmin;
	CommandId	fn_cmin;
	PLyTypeInfo result;			/* also used to store info for trigger
								 * tuple type */
	PLyTypeInfo args[FUNC_MAX_ARGS];
	int			nargs;
	PyObject   *code;			/* compiled procedure code */
	PyObject   *statics;		/* data saved across calls, local scope */
	PyObject   *globals;		/* data saved across calls, global score */
	PyObject   *me;				/* PyCObject containing pointer to this
								 * PLyProcedure */
}	PLyProcedure;


/* Python objects.
 */
typedef struct PLyPlanObject
{
	PyObject_HEAD
	void	   *plan;			/* return of an SPI_saveplan */
	int			nargs;
	Oid		   *types;
	Datum	   *values;
	PLyTypeInfo *args;
}	PLyPlanObject;

typedef struct PLyResultObject
{
	PyObject_HEAD
	/* HeapTuple *tuples; */
	PyObject   *nrows;			/* number of rows returned by query */
	PyObject   *rows;			/* data rows, or None if no data returned */
	PyObject   *status;			/* query status, SPI_OK_*, or SPI_ERR_* */
}	PLyResultObject;


/* function declarations
 */

/* Two exported functions: first is the magic telling Postgresql
 * what function call interface it implements. Second allows
 * preinitialization of the interpreter during postmaster startup.
 */
Datum		plpython_call_handler(PG_FUNCTION_ARGS);
void		plpython_init(void);

PG_FUNCTION_INFO_V1(plpython_call_handler);

/* most of the remaining of the declarations, all static
 */

/* these should only be called once at the first call
 * of plpython_call_handler.  initialize the python interpreter
 * and global data.
 */
static void PLy_init_all(void);
static void PLy_init_interp(void);
static void PLy_init_plpy(void);

/* error handler.  collects the current Python exception, if any,
 * and appends it to the error and sends it to elog
 */
static void PLy_elog(int, const char *,...);

/* call PyErr_SetString with a vprint interface
 */
static void
PLy_exception_set(PyObject *, const char *,...)
__attribute__((format(printf, 2, 3)));

/* Get the innermost python procedure called from the backend.
 */
static char *PLy_procedure_name(PLyProcedure *);

/* some utility functions
 */
static void *PLy_malloc(size_t);
static void *PLy_realloc(void *, size_t);
static void PLy_free(void *);

/* sub handlers for functions and triggers
 */
static Datum PLy_function_handler(FunctionCallInfo fcinfo, PLyProcedure *);
static HeapTuple PLy_trigger_handler(FunctionCallInfo fcinfo, PLyProcedure *);

static PyObject *PLy_function_build_args(FunctionCallInfo fcinfo, PLyProcedure *);
static PyObject *PLy_trigger_build_args(FunctionCallInfo fcinfo, PLyProcedure *,
					   HeapTuple *);
static HeapTuple PLy_modify_tuple(PLyProcedure *, PyObject *,
				 TriggerData *, HeapTuple);

static PyObject *PLy_procedure_call(PLyProcedure *, char *, PyObject *);

static PLyProcedure *PLy_procedure_get(FunctionCallInfo fcinfo,
									   Oid tgreloid);

static PLyProcedure *PLy_procedure_create(FunctionCallInfo fcinfo,
					 Oid tgreloid,
					 HeapTuple procTup, char *key);

static void PLy_procedure_compile(PLyProcedure *, const char *);
static char *PLy_procedure_munge_source(const char *, const char *);
static void PLy_procedure_delete(PLyProcedure *);

static void PLy_typeinfo_init(PLyTypeInfo *);
static void PLy_typeinfo_dealloc(PLyTypeInfo *);
static void PLy_output_datum_func(PLyTypeInfo *, Form_pg_type);
static void PLy_output_datum_func2(PLyObToDatum *, Form_pg_type);
static void PLy_input_datum_func(PLyTypeInfo *, Oid, Form_pg_type);
static void PLy_input_datum_func2(PLyDatumToOb *, Oid, Form_pg_type);
static void PLy_output_tuple_funcs(PLyTypeInfo *, TupleDesc);
static void PLy_input_tuple_funcs(PLyTypeInfo *, TupleDesc);

/* conversion functions
 */
static PyObject *PLyDict_FromTuple(PLyTypeInfo *, HeapTuple, TupleDesc);
static PyObject *PLyBool_FromString(const char *);
static PyObject *PLyFloat_FromString(const char *);
static PyObject *PLyInt_FromString(const char *);
static PyObject *PLyLong_FromString(const char *);
static PyObject *PLyString_FromString(const char *);


/* global data
 */
static int	PLy_first_call = 1;
static volatile int PLy_call_level = 0;

/*
 * Last function called by postgres backend
 */
static PLyProcedure *PLy_last_procedure = NULL;

/* this gets modified in plpython_call_handler and PLy_elog.
 * test it any old where, but do NOT modify it anywhere except
 * those two functions
 */
static volatile int PLy_restart_in_progress = 0;

static PyObject *PLy_interp_globals = NULL;
static PyObject *PLy_interp_safe_globals = NULL;
static PyObject *PLy_procedure_cache = NULL;

/* Python exceptions
 */
static PyObject *PLy_exc_error = NULL;
static PyObject *PLy_exc_fatal = NULL;
static PyObject *PLy_exc_spi_error = NULL;

/* some globals for the python module
 */
static char PLy_plan_doc[] = {
	"Store a PostgreSQL plan"
};

static char PLy_result_doc[] = {
	"Results of a PostgreSQL query"
};


#if DEBUG_EXC
volatile int exc_save_calls = 0;
volatile int exc_restore_calls = 0;
volatile int func_enter_calls = 0;
volatile int func_leave_calls = 0;
#endif

/*
 * the function definitions
 */

/*
 * This routine is a crock, and so is everyplace that calls it.  The problem
 * is that the cached form of plpython functions/queries is allocated permanently
 * (mostly via malloc()) and never released until backend exit.  Subsidiary
 * data structures such as fmgr info records therefore must live forever
 * as well.  A better implementation would store all this stuff in a per-
 * function memory context that could be reclaimed at need.  In the meantime,
 * fmgr_info_cxt must be called specifying TopMemoryContext so that whatever
 * it might allocate, and whatever the eventual function might allocate using
 * fn_mcxt, will live forever too.
 */
static void
perm_fmgr_info(Oid functionId, FmgrInfo *finfo)
{
	fmgr_info_cxt(functionId, finfo, TopMemoryContext);
}

Datum
plpython_call_handler(PG_FUNCTION_ARGS)
{
	DECLARE_EXC();
	Datum		retval;
	PLyProcedure *volatile proc = NULL;

	enter();

	PLy_init_all();

	if (SPI_connect() != SPI_OK_CONNECT)
		elog(ERROR, "could not connect to SPI manager");

	CALL_LEVEL_INC();

	SAVE_EXC();
	if (TRAP_EXC())
	{
		RESTORE_EXC();
		CALL_LEVEL_DEC();
		if (PLy_call_level == 0)
		{
			PLy_restart_in_progress = 0;
			PyErr_Clear();
		}
		else
			PLy_restart_in_progress += 1;
		if (proc)
		{
			/* note: Py_DECREF needs braces around it, as of 2003/08 */
			Py_DECREF(proc->me);
		}
		RERAISE_EXC();
	}

	/*
	 * elog(DEBUG3, "PLy_restart_in_progress is %d",
	 * PLy_restart_in_progress);
	 */

	if (CALLED_AS_TRIGGER(fcinfo))
	{
		TriggerData *tdata = (TriggerData *) fcinfo->context;
		HeapTuple	trv;

		proc = PLy_procedure_get(fcinfo,
								 RelationGetRelid(tdata->tg_relation));
		trv = PLy_trigger_handler(fcinfo, proc);
		retval = PointerGetDatum(trv);
	}
	else
	{
		proc = PLy_procedure_get(fcinfo, InvalidOid);
		retval = PLy_function_handler(fcinfo, proc);
	}

	CALL_LEVEL_DEC();
	RESTORE_EXC();

	Py_DECREF(proc->me);
	refc(proc->me);

	return retval;
}

/* trigger and function sub handlers
 *
 * the python function is expected to return Py_None if the tuple is
 * acceptable and unmodified.  Otherwise it should return a PyString
 * object who's value is SKIP, or MODIFY.  SKIP means don't perform
 * this action.  MODIFY means the tuple has been modified, so update
 * tuple and perform action.  SKIP and MODIFY assume the trigger fires
 * BEFORE the event and is ROW level.  postgres expects the function
 * to take no arguments and return an argument of type trigger.
 */
HeapTuple
PLy_trigger_handler(FunctionCallInfo fcinfo, PLyProcedure * proc)
{
	DECLARE_EXC();
	HeapTuple	rv = NULL;
	PyObject   *volatile plargs = NULL;
	PyObject   *volatile plrv = NULL;

	enter();

	SAVE_EXC();
	if (TRAP_EXC())
	{
		RESTORE_EXC();

		Py_XDECREF(plargs);
		Py_XDECREF(plrv);

		RERAISE_EXC();
	}

	plargs = PLy_trigger_build_args(fcinfo, proc, &rv);
	plrv = PLy_procedure_call(proc, "TD", plargs);

	/*
	 * Disconnect from SPI manager
	 */
	if (SPI_finish() != SPI_OK_FINISH)
		elog(ERROR, "SPI_finish failed");

	if (plrv == NULL)
		elog(FATAL, "PLy_procedure_call returned NULL");

	if (PLy_restart_in_progress)
		elog(FATAL, "restart in progress not expected");

	/*
	 * return of None means we're happy with the tuple
	 */
	if (plrv != Py_None)
	{
		char	   *srv;

		if (!PyString_Check(plrv))
			elog(ERROR, "expected trigger to return None or a String");

		srv = PyString_AsString(plrv);
		if (strcasecmp(srv, "SKIP") == 0)
			rv = NULL;
		else if (strcasecmp(srv, "MODIFY") == 0)
		{
			TriggerData *tdata = (TriggerData *) fcinfo->context;

			if ((TRIGGER_FIRED_BY_INSERT(tdata->tg_event)) ||
				(TRIGGER_FIRED_BY_UPDATE(tdata->tg_event)))
				rv = PLy_modify_tuple(proc, plargs, tdata, rv);
			else
				elog(WARNING, "ignoring modified tuple in DELETE trigger");
		}
		else if (strcasecmp(srv, "OK"))
		{
			/*
			 * hmmm, perhaps they only read the pltcl page, not a
			 * surprising thing since i've written no documentation, so
			 * accept a belated OK
			 */
			elog(ERROR, "expected return to be \"SKIP\" or \"MODIFY\"");
		}
	}

	Py_DECREF(plargs);
	Py_DECREF(plrv);

	RESTORE_EXC();

	return rv;
}

HeapTuple
PLy_modify_tuple(PLyProcedure * proc, PyObject * pltd, TriggerData *tdata,
				 HeapTuple otup)
{
	DECLARE_EXC();
	PyObject   *volatile plntup;
	PyObject   *volatile plkeys;
	PyObject   *volatile platt;
	PyObject   *volatile plval;
	PyObject   *volatile plstr;
	HeapTuple	rtup;
	int			natts,
				i,
				attn,
				atti;
	int		   *volatile modattrs;
	Datum	   *volatile modvalues;
	char	   *volatile modnulls;
	TupleDesc	tupdesc;

	plntup = plkeys = platt = plval = plstr = NULL;
	modattrs = NULL;
	modvalues = NULL;
	modnulls = NULL;

	enter();

	SAVE_EXC();
	if (TRAP_EXC())
	{
		RESTORE_EXC();

		Py_XDECREF(plntup);
		Py_XDECREF(plkeys);
		Py_XDECREF(platt);
		Py_XDECREF(plval);
		Py_XDECREF(plstr);

		if (modnulls)
			pfree(modnulls);
		if (modvalues)
			pfree(modvalues);
		if (modattrs)
			pfree(modattrs);

		RERAISE_EXC();
	}

	if ((plntup = PyDict_GetItemString(pltd, "new")) == NULL)
		elog(ERROR, "TD[\"new\"] deleted, unable to modify tuple");
	if (!PyDict_Check(plntup))
		elog(ERROR, "TD[\"new\"] is not a dictionary object");
	Py_INCREF(plntup);

	plkeys = PyDict_Keys(plntup);
	natts = PyList_Size(plkeys);

	/* +1 to avoid palloc(0) on empty tuple */
	modattrs = palloc(natts * sizeof(int) + 1);
	modvalues = palloc(natts * sizeof(Datum) + 1);
	modnulls = palloc(natts + 1);

	tupdesc = tdata->tg_relation->rd_att;

	for (i = 0; i < natts; i++)
	{
		char	   *src;

		platt = PyList_GetItem(plkeys, i);
		if (!PyString_Check(platt))
			elog(ERROR, "attribute name is not a string");
		attn = SPI_fnumber(tupdesc, PyString_AsString(platt));
		if (attn == SPI_ERROR_NOATTRIBUTE)
			elog(ERROR, "invalid attribute \"%s\" in tuple",
				 PyString_AsString(platt));
		atti = attn - 1;

		plval = PyDict_GetItem(plntup, platt);
		if (plval == NULL)
			elog(FATAL, "python interpreter is probably corrupted");

		Py_INCREF(plval);

		modattrs[i] = attn;