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/*-------------------------------------------------------------------------
*
* conversioncmds.c
* conversion creation command support code
*
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/commands/conversioncmds.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/htup_details.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/pg_conversion.h"
#include "catalog/pg_type.h"
#include "commands/alter.h"
#include "commands/conversioncmds.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "parser/parse_func.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/syscache.h"
/*
* CREATE CONVERSION
*/
ObjectAddress
CreateConversionCommand(CreateConversionStmt *stmt)
{
Oid namespaceId;
char *conversion_name;
AclResult aclresult;
int from_encoding;
int to_encoding;
Oid funcoid;
const char *from_encoding_name = stmt->for_encoding_name;
const char *to_encoding_name = stmt->to_encoding_name;
List *func_name = stmt->func_name;
static const Oid funcargs[] = {INT4OID, INT4OID, CSTRINGOID, INTERNALOID, INT4OID, BOOLOID};
char result[1];
Datum funcresult;
/* Convert list of names to a name and namespace */
namespaceId = QualifiedNameGetCreationNamespace(stmt->conversion_name,
&conversion_name);
/* Check we have creation rights in target namespace */
aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(), ACL_CREATE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_SCHEMA,
get_namespace_name(namespaceId));
/* Check the encoding names */
from_encoding = pg_char_to_encoding(from_encoding_name);
if (from_encoding < 0)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("source encoding \"%s\" does not exist",
from_encoding_name)));
to_encoding = pg_char_to_encoding(to_encoding_name);
if (to_encoding < 0)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("destination encoding \"%s\" does not exist",
to_encoding_name)));
/*
* We consider conversions to or from SQL_ASCII to be meaningless. (If
* you wish to change this, note that pg_do_encoding_conversion() and its
* sister functions have hard-wired fast paths for any conversion in which
* the source or target encoding is SQL_ASCII, so that an encoding
* conversion function declared for such a case will never be used.)
*/
if (from_encoding == PG_SQL_ASCII || to_encoding == PG_SQL_ASCII)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("encoding conversion to or from \"SQL_ASCII\" is not supported")));
/*
* Check the existence of the conversion function. Function name could be
* a qualified name.
*/
funcoid = LookupFuncName(func_name, sizeof(funcargs) / sizeof(Oid),
funcargs, false);
/* Check it returns int4, else it's probably the wrong function */
if (get_func_rettype(funcoid) != INT4OID)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("encoding conversion function %s must return type %s",
NameListToString(func_name), "integer")));
/* Check we have EXECUTE rights for the function */
aclresult = pg_proc_aclcheck(funcoid, GetUserId(), ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_FUNCTION,
NameListToString(func_name));
/*
* Check that the conversion function is suitable for the requested source
* and target encodings. We do that by calling the function with an empty
* string; the conversion function should throw an error if it can't
* perform the requested conversion.
*/
funcresult = OidFunctionCall6(funcoid,
Int32GetDatum(from_encoding),
Int32GetDatum(to_encoding),
CStringGetDatum(""),
CStringGetDatum(result),
Int32GetDatum(0),
BoolGetDatum(false));
/*
* The function should return 0 for empty input. Might as well check that,
* too.
*/
if (DatumGetInt32(funcresult) != 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("encoding conversion function %s returned incorrect result for empty input",
NameListToString(func_name))));
/*
* All seem ok, go ahead (possible failure would be a duplicate conversion
* name)
*/
return ConversionCreate(conversion_name, namespaceId, GetUserId(),
from_encoding, to_encoding, funcoid, stmt->def);
}
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