postgres/src/pl/plpython/plpy_main.c

/*
 * PL/Python main entry points
 *
 * src/pl/plpython/plpy_main.c
 */

#include "postgres.h"

#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "commands/trigger.h"
#include "executor/spi.h"
#include "miscadmin.h"
#include "utils/guc.h"
#include "utils/syscache.h"

#include "plpython.h"

#include "plpy_main.h"

#include "plpy_elog.h"
#include "plpy_exec.h"
#include "plpy_plpymodule.h"
#include "plpy_procedure.h"
#include "plpy_subxactobject.h"


/*
 * exported functions
 */

#if PY_MAJOR_VERSION >= 3
/* Use separate names to avoid clash in pg_pltemplate */
#define plpython_validator plpython3_validator
#define plpython_call_handler plpython3_call_handler
#define plpython_inline_handler plpython3_inline_handler
#endif

extern void _PG_init(void);
extern Datum plpython_validator(PG_FUNCTION_ARGS);
extern Datum plpython_call_handler(PG_FUNCTION_ARGS);
extern Datum plpython_inline_handler(PG_FUNCTION_ARGS);

#if PY_MAJOR_VERSION < 3
/* Define aliases plpython2_call_handler etc */
extern Datum plpython2_validator(PG_FUNCTION_ARGS);
extern Datum plpython2_call_handler(PG_FUNCTION_ARGS);
extern Datum plpython2_inline_handler(PG_FUNCTION_ARGS);
#endif

PG_MODULE_MAGIC;

PG_FUNCTION_INFO_V1(plpython_validator);
PG_FUNCTION_INFO_V1(plpython_call_handler);
PG_FUNCTION_INFO_V1(plpython_inline_handler);

#if PY_MAJOR_VERSION < 3
PG_FUNCTION_INFO_V1(plpython2_validator);
PG_FUNCTION_INFO_V1(plpython2_call_handler);
PG_FUNCTION_INFO_V1(plpython2_inline_handler);
#endif


static bool PLy_procedure_is_trigger(Form_pg_proc procStruct);
static void plpython_error_callback(void *arg);
static void plpython_inline_error_callback(void *arg);
static void PLy_init_interp(void);

static const int plpython_python_version = PY_MAJOR_VERSION;

/* initialize global variables */
PyObject *PLy_interp_globals = NULL;


void
_PG_init(void)
{
	/* Be sure we do initialization only once (should be redundant now) */
	static bool inited = false;
	const int **version_ptr;

	if (inited)
		return;

	/* Be sure we don't run Python 2 and 3 in the same session (might crash) */
	version_ptr = (const int **) find_rendezvous_variable("plpython_python_version");
	if (!(*version_ptr))
		*version_ptr = &plpython_python_version;
	else
	{
		if (**version_ptr != plpython_python_version)
			ereport(FATAL,
					(errmsg("Python major version mismatch in session"),
					 errdetail("This session has previously used Python major version %d, and it is now attempting to use Python major version %d.",
							   **version_ptr, plpython_python_version),
					 errhint("Start a new session to use a different Python major version.")));
	}

	pg_bindtextdomain(TEXTDOMAIN);

#if PY_MAJOR_VERSION >= 3
	PyImport_AppendInittab("plpy", PyInit_plpy);
#endif
	Py_Initialize();
#if PY_MAJOR_VERSION >= 3
	PyImport_ImportModule("plpy");
#endif
	PLy_init_interp();
	PLy_init_plpy();
	if (PyErr_Occurred())
		PLy_elog(FATAL, "untrapped error in initialization");

	init_procedure_caches();

	explicit_subtransactions = NIL;

	inited = true;
}

/*
 * This should only be called once from _PG_init. Initialize the Python
 * interpreter and global data.
 */
void
PLy_init_interp(void)
{
	static PyObject *PLy_interp_safe_globals = NULL;
	PyObject   *mainmod;

	mainmod = PyImport_AddModule("__main__");
	if (mainmod == NULL || PyErr_Occurred())
		PLy_elog(ERROR, "could not import \"__main__\" module");
	Py_INCREF(mainmod);
	PLy_interp_globals = PyModule_GetDict(mainmod);
	PLy_interp_safe_globals = PyDict_New();
	PyDict_SetItemString(PLy_interp_globals, "GD", PLy_interp_safe_globals);
	Py_DECREF(mainmod);
	if (PLy_interp_globals == NULL || PyErr_Occurred())
		PLy_elog(ERROR, "could not initialize globals");
}

Datum
plpython_validator(PG_FUNCTION_ARGS)
{
	Oid			funcoid = PG_GETARG_OID(0);
	HeapTuple	tuple;
	Form_pg_proc procStruct;
	bool		is_trigger;

	if (!check_function_bodies)
	{
		PG_RETURN_VOID();
	}

	/* Get the new function's pg_proc entry */
	tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcoid));
	if (!HeapTupleIsValid(tuple))
		elog(ERROR, "cache lookup failed for function %u", funcoid);
	procStruct = (Form_pg_proc) GETSTRUCT(tuple);

	is_trigger = PLy_procedure_is_trigger(procStruct);

	ReleaseSysCache(tuple);

	PLy_procedure_get(funcoid, is_trigger);

	PG_RETURN_VOID();
}

#if PY_MAJOR_VERSION < 3
Datum
plpython2_validator(PG_FUNCTION_ARGS)
{
	return plpython_validator(fcinfo);
}
#endif   /* PY_MAJOR_VERSION < 3 */

Datum
plpython_call_handler(PG_FUNCTION_ARGS)
{
	Datum		retval;
	PLyProcedure *save_curr_proc;
	ErrorContextCallback plerrcontext;

	if (SPI_connect() != SPI_OK_CONNECT)
		elog(ERROR, "SPI_connect failed");

	save_curr_proc = PLy_curr_procedure;

	/*
	 * Setup error traceback support for ereport()
	 */
	plerrcontext.callback = plpython_error_callback;
	plerrcontext.previous = error_context_stack;
	error_context_stack = &plerrcontext;

	PG_TRY();
	{
		PLyProcedure *proc;

		if (CALLED_AS_TRIGGER(fcinfo))
		{
			HeapTuple	trv;

			proc = PLy_procedure_get(fcinfo->flinfo->fn_oid, true);
			PLy_curr_procedure = proc;
			trv = PLy_exec_trigger(fcinfo, proc);
			retval = PointerGetDatum(trv);
		}
		else
		{
			proc = PLy_procedure_get(fcinfo->flinfo->fn_oid, false);
			PLy_curr_procedure = proc;
			retval = PLy_exec_function(fcinfo, proc);
		}
	}
	PG_CATCH();
	{
		PLy_curr_procedure = save_curr_proc;
		PyErr_Clear();
		PG_RE_THROW();
	}
	PG_END_TRY();

	/* Pop the error context stack */
	error_context_stack = plerrcontext.previous;

	PLy_curr_procedure = save_curr_proc;

	return retval;
}

#if PY_MAJOR_VERSION < 3
Datum
plpython2_call_handler(PG_FUNCTION_ARGS)
{
	return plpython_call_handler(fcinfo);
}
#endif   /* PY_MAJOR_VERSION < 3 */

Datum
plpython_inline_handler(PG_FUNCTION_ARGS)
{
	InlineCodeBlock *codeblock = (InlineCodeBlock *) DatumGetPointer(PG_GETARG_DATUM(0));
	FunctionCallInfoData fake_fcinfo;
	FmgrInfo	flinfo;
	PLyProcedure *save_curr_proc;
	PLyProcedure proc;
	ErrorContextCallback plerrcontext;

	if (SPI_connect() != SPI_OK_CONNECT)
		elog(ERROR, "SPI_connect failed");

	save_curr_proc = PLy_curr_procedure;

	/*
	 * Setup error traceback support for ereport()
	 */
	plerrcontext.callback = plpython_inline_error_callback;
	plerrcontext.previous = error_context_stack;
	error_context_stack = &plerrcontext;

	MemSet(&fake_fcinfo, 0, sizeof(fake_fcinfo));
	MemSet(&flinfo, 0, sizeof(flinfo));
	fake_fcinfo.flinfo = &flinfo;
	flinfo.fn_oid = InvalidOid;
	flinfo.fn_mcxt = CurrentMemoryContext;

	MemSet(&proc, 0, sizeof(PLyProcedure));
	proc.pyname = PLy_strdup("__plpython_inline_block");
	proc.result.out.d.typoid = VOIDOID;

	PG_TRY();
	{
		PLy_procedure_compile(&proc, codeblock->source_text);
		PLy_curr_procedure = &proc;
		PLy_exec_function(&fake_fcinfo, &proc);
	}
	PG_CATCH();
	{
		PLy_procedure_delete(&proc);
		PLy_curr_procedure = save_curr_proc;
		PyErr_Clear();
		PG_RE_THROW();
	}
	PG_END_TRY();

	PLy_procedure_delete(&proc);

	/* Pop the error context stack */
	error_context_stack = plerrcontext.previous;

	PLy_curr_procedure = save_curr_proc;

	PG_RETURN_VOID();
}

#if PY_MAJOR_VERSION < 3
Datum
plpython2_inline_handler(PG_FUNCTION_ARGS)
{
	return plpython_inline_handler(fcinfo);
}
#endif   /* PY_MAJOR_VERSION < 3 */

static bool PLy_procedure_is_trigger(Form_pg_proc procStruct)
{
	return (procStruct->prorettype == TRIGGEROID ||
			(procStruct->prorettype == OPAQUEOID &&
			 procStruct->pronargs == 0));
}

static void
plpython_error_callback(void *arg)
{
	if (PLy_curr_procedure)
		errcontext("PL/Python function \"%s\"",
				   PLy_procedure_name(PLy_curr_procedure));
}

static void
plpython_inline_error_callback(void *arg)
{
	errcontext("PL/Python anonymous code block");
}