C++ PG_RETURN_NULL函数代码示例

Datum x509_get_version(PG_FUNCTION_ARGS) {
	bytea *raw;
	X509 *cert;
	int version;

	// check for null value.
	raw = PG_GETARG_BYTEA_P(0);
	if (raw == NULL || VARSIZE(raw) == VARHDRSZ) {
		PG_RETURN_NULL();
	}

	cert = x509_from_bytea(raw);
	if (cert == NULL) {
		ereport(ERROR,
				(errcode(ERRCODE_DATA_CORRUPTED), errmsg(
						"unable to decode X509 record")));
	}

	version = X509_get_version(cert);
	X509_free(cert);

	PG_RETURN_INT32(version);
}

Datum
pg_stat_get_backend_wait_event_type(PG_FUNCTION_ARGS)
{
	int32		beid = PG_GETARG_INT32(0);
	PgBackendStatus *beentry;
	PGPROC	   *proc;
	const char *wait_event_type;

	if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
		wait_event_type = "<backend information not available>";
	else if (!has_privs_of_role(GetUserId(), beentry->st_userid))
		wait_event_type = "<insufficient privilege>";
	else
	{
		proc = BackendPidGetProc(beentry->st_procpid);
		wait_event_type = pgstat_get_wait_event_type(proc->wait_event_info);
	}

	if (!wait_event_type)
		PG_RETURN_NULL();

	PG_RETURN_TEXT_P(cstring_to_text(wait_event_type));
}

Datum
fetchval(PG_FUNCTION_ARGS)
{
	HStore	   *hs = PG_GETARG_HS(0);
	text	   *key = PG_GETARG_TEXT_P(1);
	HEntry	   *entry;
	text	   *out;

	if ((entry = findkey(hs, VARDATA(key), VARSIZE(key) - VARHDRSZ)) == NULL || entry->valisnull)
	{
		PG_FREE_IF_COPY(hs, 0);
		PG_FREE_IF_COPY(key, 1);
		PG_RETURN_NULL();
	}

	out = palloc(VARHDRSZ + entry->vallen);
	memcpy(VARDATA(out), STRPTR(hs) + entry->pos + entry->keylen, entry->vallen);
	SET_VARSIZE(out, VARHDRSZ + entry->vallen);

	PG_FREE_IF_COPY(hs, 0);
	PG_FREE_IF_COPY(key, 1);
	PG_RETURN_POINTER(out);
}

Datum
lexize_bycurrent(PG_FUNCTION_ARGS)
{
	Datum		res;

	SET_FUNCOID();
	if (currect_dictionary_id == 0)
		ereport(ERROR,
				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
				 errmsg("no currect dictionary"),
				 errhint("Execute select set_curdict().")));

	res = DirectFunctionCall3(
							  lexize,
							  ObjectIdGetDatum(currect_dictionary_id),
							  PG_GETARG_DATUM(0),
							  (Datum) 0
		);
	if (res)
		PG_RETURN_DATUM(res);
	else
		PG_RETURN_NULL();
}

/*
 * SQL function: format_type(type_oid, typemod)
 *
 * `type_oid' is from pg_type.oid, `typemod' is from
 * pg_attribute.atttypmod. This function will get the type name and
 * format it and the modifier to canonical SQL format, if the type is
 * a standard type. Otherwise you just get pg_type.typname back,
 * double quoted if it contains funny characters or matches a keyword.
 *
 * If typemod is NULL then we are formatting a type name in a context where
 * no typemod is available, eg a function argument or result type.	This
 * yields a slightly different result from specifying typemod = -1 in some
 * cases.  Given typemod = -1 we feel compelled to produce an output that
 * the parser will interpret as having typemod -1, so that pg_dump will
 * produce CREATE TABLE commands that recreate the original state.	But
 * given NULL typemod, we assume that the parser's interpretation of
 * typemod doesn't matter, and so we are willing to output a slightly
 * "prettier" representation of the same type.	For example, type = bpchar
 * and typemod = NULL gets you "character", whereas typemod = -1 gets you
 * "bpchar" --- the former will be interpreted as character(1) by the
 * parser, which does not yield typemod -1.
 *
 * XXX encoding a meaning in typemod = NULL is ugly; it'd have been
 * cleaner to make two functions of one and two arguments respectively.
 * Not worth changing it now, however.
 */
Datum
format_type(PG_FUNCTION_ARGS)
{
	Oid			type_oid;
	int32		typemod;
	char	   *result;

	/* Since this function is not strict, we must test for null args */
	if (PG_ARGISNULL(0))
		PG_RETURN_NULL();

	type_oid = PG_GETARG_OID(0);

	if (PG_ARGISNULL(1))
		result = format_type_internal(type_oid, -1, false, true);
	else
	{
		typemod = PG_GETARG_INT32(1);
		result = format_type_internal(type_oid, typemod, true, true);
	}

	PG_RETURN_TEXT_P(cstring_to_text(result));
}

Datum LWGEOM_x_point(PG_FUNCTION_ARGS)
{
	GSERIALIZED *geom;
	LWGEOM *lwgeom;
	LWPOINT *point = NULL;
	POINT2D p;

	geom = (GSERIALIZED *)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));

	if ( gserialized_get_type(geom) != POINTTYPE )
		lwerror("Argument to X() must be a point");

	lwgeom = lwgeom_from_gserialized(geom);
	point = lwgeom_as_lwpoint(lwgeom);
	
	if ( lwgeom_is_empty(lwgeom) )
		PG_RETURN_NULL();

	getPoint2d_p(point->point, 0, &p);

	PG_FREE_IF_COPY(geom, 0);
	PG_RETURN_FLOAT8(p.x);
}

Datum LWGEOM_line_desegmentize(PG_FUNCTION_ARGS)
{
	GSERIALIZED *geom = PG_GETARG_GSERIALIZED_P(0);
	GSERIALIZED *ret;
	LWGEOM *igeom = NULL, *ogeom = NULL;

	POSTGIS_DEBUG(2, "LWGEOM_line_desegmentize.");

	igeom = lwgeom_from_gserialized(geom);
	ogeom = lwgeom_unstroke(igeom);
	lwgeom_free(igeom);

	if (ogeom == NULL)
	{
		PG_FREE_IF_COPY(geom, 0);
		PG_RETURN_NULL();
	}

	ret = geometry_serialize(ogeom);
	lwgeom_free(ogeom);
	PG_FREE_IF_COPY(geom, 0);
	PG_RETURN_POINTER(ret);
}

PGDLLEXPORT
Datum
hello( PG_FUNCTION_ARGS )
{
   // variable declarations
   char greet[] = "Hello, ";
   text *towhom;
   int greetlen;
   int towhomlen;
   text *greeting;
   int  greeting_size;

   // Get arguments.  If we declare our function as STRICT, then
   // this check is superfluous.
   if(PG_ARGISNULL(0)) {
      PG_RETURN_NULL();
   }
   towhom = PG_GETARG_TEXT_P(0);

   // Calculate string sizes.
    greetlen = strlen(greet);  
   towhomlen = VARSIZE(towhom)-VARHDRSZ;

   // Allocate memory and set data structure size.
   greeting = (text *)palloc( greetlen + towhomlen );
   //VARATT_SIZEP( greeting ) = greetlen + towhomlen  + VARHDRSZ;//postgres 7.4
   greeting_size=greetlen+towhomlen+VARHDRSZ;
   SET_VARSIZE(greeting,greeting_size);

   // Construct greeting string.
   strncpy( VARDATA(greeting), greet, greetlen );
   strncpy( VARDATA(greeting) + greetlen,
            VARDATA(towhom),
            towhomlen );

   PG_RETURN_TEXT_P( greeting );
}

/*
 * Read a section of a file, returning it as text
 */
Datum
pg_read_file(PG_FUNCTION_ARGS)
{
	text	   *filename_t = PG_GETARG_TEXT_PP(0);
	int64		seek_offset = 0;
	int64		bytes_to_read = -1;
	bool		missing_ok = false;
	char	   *filename;
	text	   *result;

	if (!superuser())
		ereport(ERROR,
				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
				 (errmsg("must be superuser to read files"))));

	/* handle optional arguments */
	if (PG_NARGS() >= 3)
	{
		seek_offset = PG_GETARG_INT64(1);
		bytes_to_read = PG_GETARG_INT64(2);

		if (bytes_to_read < 0)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
					 errmsg("requested length cannot be negative")));
	}
	if (PG_NARGS() >= 4)
		missing_ok = PG_GETARG_BOOL(3);

	filename = convert_and_check_filename(filename_t);

	result = read_text_file(filename, seek_offset, bytes_to_read, missing_ok);
	if (result)
		PG_RETURN_TEXT_P(result);
	else
		PG_RETURN_NULL();
}

Datum pcpatch_in(PG_FUNCTION_ARGS)
{
	char *str = PG_GETARG_CSTRING(0);
	/* Datum geog_oid = PG_GETARG_OID(1); Not needed. */
	uint32 typmod = 0, pcid = 0;
	PCPATCH *patch;
	SERIALIZED_PATCH *serpatch = NULL;

	if ( (PG_NARGS()>2) && (!PG_ARGISNULL(2)) )
	{
		typmod = PG_GETARG_INT32(2);
		pcid = pcid_from_typmod(typmod);
	}

	/* Empty string. */
	if ( str[0] == '\0' )
	{
		ereport(ERROR,(errmsg("pcpatch parse error - empty string")));
	}

	/* Binary or text form? Let's find out. */
	if ( str[0] == '0' )
	{
		/* Hex-encoded binary */
		patch = pc_patch_from_hexwkb(str, strlen(str), fcinfo);
		pcid_consistent(patch->schema->pcid, pcid);
		serpatch = pc_patch_serialize(patch, NULL);
		pc_patch_free(patch);
	}
	else
	{
		ereport(ERROR,(errmsg("parse error - support for text format not yet implemented")));
	}

	if ( serpatch ) PG_RETURN_POINTER(serpatch);
	else PG_RETURN_NULL();
}

Datum
linterp_int32(PG_FUNCTION_ARGS)
{
	float8 y0;
	float8 y1;
	float8 p;
	float8 r;
	int32 result;
	bool eq_bounds = false;
	bool eq_abscissas = false;
	
	/* Common */
	p = linterp_abscissa(fcinfo, &eq_bounds, &eq_abscissas);
	
	/* Ordinate type specific code*/
	y0 = (float8)PG_GETARG_INT32(2);
	y1 = (float8)PG_GETARG_INT32(4);
	
	if ( eq_bounds )
	{
		if ( eq_abscissas && y0 == y1 )
			r = y0;
		else 
			PG_RETURN_NULL();
	}
	else 
	{
		r = round(y0+p*(y1-y0));
		if ( r < INT_MIN || r > INT_MAX )
			ereport(ERROR,
					(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
					 errmsg("value \"%f\" is out of range for type integer", r)));
	}
	
	result = (int32)r;
	PG_RETURN_INT32(result);
}

Datum
xpath_string(PG_FUNCTION_ARGS)
{
	text	   *document = PG_GETARG_TEXT_P(0);
	text	   *xpathsupp = PG_GETARG_TEXT_P(1);		/* XPath expression */
	xmlChar    *xpath;
	int32		pathsize;
	text	   *xpres;
	xmlXPathObjectPtr res;
	xpath_workspace workspace;

	pathsize = VARSIZE(xpathsupp) - VARHDRSZ;

	/*
	 * We encapsulate the supplied path with "string()" = 8 chars + 1 for NUL
	 * at end
	 */
	/* We could try casting to string using the libxml function? */

	xpath = (xmlChar *) palloc(pathsize + 9);
	strncpy((char *) xpath, "string(", 7);
	memcpy((char *) (xpath + 7), VARDATA(xpathsupp), pathsize);
	xpath[pathsize + 7] = ')';
	xpath[pathsize + 8] = '\0';

	res = pgxml_xpath(document, xpath, &workspace);

	xpres = pgxml_result_to_text(res, NULL, NULL, NULL);

	cleanup_workspace(&workspace);

	pfree(xpath);

	if (xpres == NULL)
		PG_RETURN_NULL();
	PG_RETURN_TEXT_P(xpres);
}

Datum
xpath_string(PG_FUNCTION_ARGS)
{
	xmlChar    *xpath;
	int32		pathsize;
	text
			   *xpathsupp,
			   *xpres;

	/* PG_GETARG_TEXT_P(0) is document buffer */
	xpathsupp = PG_GETARG_TEXT_P(1);	/* XPath expression */

	pathsize = VARSIZE(xpathsupp) - VARHDRSZ;

	/*
	 * We encapsulate the supplied path with "string()" = 8 chars + 1 for NUL
	 * at end
	 */
	/* We could try casting to string using the libxml function? */

	xpath = (xmlChar *) palloc(pathsize + 9);
	memcpy((char *) (xpath + 7), VARDATA(xpathsupp), pathsize);
	strncpy((char *) xpath, "string(", 7);
	xpath[pathsize + 7] = ')';
	xpath[pathsize + 8] = '\0';

	xpres = pgxml_result_to_text(
								 pgxml_xpath(PG_GETARG_TEXT_P(0), xpath),
								 NULL, NULL, NULL);

	xmlCleanupParser();
	pfree(xpath);

	if (xpres == NULL)
		PG_RETURN_NULL();
	PG_RETURN_TEXT_P(xpres);
}

Datum
pgx_complex_near(PG_FUNCTION_ARGS) {
    double re[2];
    double im[2];
    double p, q;
    int i;

    // unwrap values.    
    for (i = 0; i < 2; i++) {
        HeapTupleHeader t = PG_GETARG_HEAPTUPLEHEADER(i);
        bool isnull[2];

        Datum dr = GetAttributeByName(t, "re", &isnull[0]);
        Datum di = GetAttributeByName(t, "im", &isnull[1]);

        // STRICT prevents the 'complex' value from being null but does
        // not prevent its components from being null.        
        if (isnull[0] || isnull[1]) {
            PG_RETURN_NULL();
        }
        
        re[i] = DatumGetFloat8(dr);
        im[i] = DatumGetFloat8(di);
    }

    // compute distance between points, distance of points from origin.
    p = hypot(re[0] - re[1], im[0] - im[1]);
    q = hypot(re[0], im[0]) + hypot(re[1], im[1]);
    
    if (q == 0) {
        PG_RETURN_BOOL(1);
    }
    
    // we consider the points 'near' each other if the distance between them is small
    // relative to the size of them. 
    PG_RETURN_BOOL(p / q < 1e-8); 
}

Datum
quantile_numeric_array(PG_FUNCTION_ARGS)
{
    
    int i, idx = 0;
    struct_numeric * data;
    Numeric * result;
    
    CHECK_AGG_CONTEXT("quantile_numeric_array", fcinfo);
    
    if (PG_ARGISNULL(0)) {
        PG_RETURN_NULL();
    }
    
    data = (struct_numeric*)PG_GETARG_POINTER(0);
    
    result = palloc(data->nquantiles * sizeof(Numeric));
    
    qsort(data->elements, data->next, sizeof(Numeric), &numeric_comparator);

    for (i = 0; i < data->nquantiles; i++) {
        
        if ((data->quantiles[i] > 0) && (data->quantiles[i] < 1)) {
            idx = (int)ceil(data->next * data->quantiles[i]) - 1;
        } else if (data->quantiles[i] <= 0) {
            idx = 0;
        } else if (data->quantiles[i] >= 1) {
            idx = data->next - 1;
        }
        
        result[i] = data->elements[idx];
        
    }

    return numeric_to_array(fcinfo, result, data->nquantiles);

}