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postgresql/contrib/dblink/dblink.c
Alvaro Herrera 2466d6654f
libpq-be-fe-helpers.h: wrap new cancel APIs 
Commit 61461a300c introduced new functions to libpq for cancelling
queries.  This commit introduces a helper function that backend-side
libraries and extensions can use to invoke those.  This function takes a
timeout and can itself be interrupted while it is waiting for a cancel
request to be sent and processed, instead of being blocked.

This replaces the usage of the old functions in postgres_fdw and dblink.

Finally, it also adds some test coverage for the cancel support in
postgres_fdw.

Author: Jelte Fennema-Nio <postgres@jeltef.nl>
Discussion: https://postgr.es/m/CAGECzQT_VgOWWENUqvUV9xQmbaCyXjtRRAYO8W07oqashk_N+g@mail.gmail.com
2024-03-28 11:31:03 +01:00

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/*
* dblink.c
*
* Functions returning results from a remote database
*
* Joe Conway <mail@joeconway.com>
* And contributors:
* Darko Prenosil <Darko.Prenosil@finteh.hr>
* Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
*
* contrib/dblink/dblink.c
* Copyright (c) 2001-2024, PostgreSQL Global Development Group
* ALL RIGHTS RESERVED;
*
* Permission to use, copy, modify, and distribute this software and its
* documentation for any purpose, without fee, and without a written agreement
* is hereby granted, provided that the above copyright notice and this
* paragraph and the following two paragraphs appear in all copies.
*
* IN NO EVENT SHALL THE AUTHOR OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
* DOCUMENTATION, EVEN IF THE AUTHOR OR DISTRIBUTORS HAVE BEEN ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* THE AUTHOR AND DISTRIBUTORS SPECIFICALLY DISCLAIMS ANY WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE AUTHOR AND DISTRIBUTORS HAS NO OBLIGATIONS TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
*/
#include "postgres.h"
#include <limits.h>
#include "access/htup_details.h"
#include "access/relation.h"
#include "access/reloptions.h"
#include "access/table.h"
#include "catalog/namespace.h"
#include "catalog/pg_foreign_data_wrapper.h"
#include "catalog/pg_foreign_server.h"
#include "catalog/pg_type.h"
#include "catalog/pg_user_mapping.h"
#include "executor/spi.h"
#include "foreign/foreign.h"
#include "funcapi.h"
#include "lib/stringinfo.h"
#include "libpq-fe.h"
#include "libpq/libpq-be.h"
#include "libpq/libpq-be-fe-helpers.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "parser/scansup.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/varlena.h"
#include "utils/wait_event.h"
PG_MODULE_MAGIC;
typedef struct remoteConn
{
PGconn *conn; /* Hold the remote connection */
int openCursorCount; /* The number of open cursors */
bool newXactForCursor; /* Opened a transaction for a cursor */
} remoteConn;
typedef struct storeInfo
{
FunctionCallInfo fcinfo;
Tuplestorestate *tuplestore;
AttInMetadata *attinmeta;
MemoryContext tmpcontext;
char **cstrs;
/* temp storage for results to avoid leaks on exception */
PGresult *last_res;
PGresult *cur_res;
} storeInfo;
/*
* Internal declarations
*/
static Datum dblink_record_internal(FunctionCallInfo fcinfo, bool is_async);
static void prepTuplestoreResult(FunctionCallInfo fcinfo);
static void materializeResult(FunctionCallInfo fcinfo, PGconn *conn,
PGresult *res);
static void materializeQueryResult(FunctionCallInfo fcinfo,
PGconn *conn,
const char *conname,
const char *sql,
bool fail);
static PGresult *storeQueryResult(volatile storeInfo *sinfo, PGconn *conn, const char *sql);
static void storeRow(volatile storeInfo *sinfo, PGresult *res, bool first);
static remoteConn *getConnectionByName(const char *name);
static HTAB *createConnHash(void);
static void createNewConnection(const char *name, remoteConn *rconn);
static void deleteConnection(const char *name);
static char **get_pkey_attnames(Relation rel, int16 *indnkeyatts);
static char **get_text_array_contents(ArrayType *array, int *numitems);
static char *get_sql_insert(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals, char **tgt_pkattvals);
static char *get_sql_delete(Relation rel, int *pkattnums, int pknumatts, char **tgt_pkattvals);
static char *get_sql_update(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals, char **tgt_pkattvals);
static char *quote_ident_cstr(char *rawstr);
static int get_attnum_pk_pos(int *pkattnums, int pknumatts, int key);
static HeapTuple get_tuple_of_interest(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals);
static Relation get_rel_from_relname(text *relname_text, LOCKMODE lockmode, AclMode aclmode);
static char *generate_relation_name(Relation rel);
static void dblink_connstr_check(const char *connstr);
static bool dblink_connstr_has_pw(const char *connstr);
static void dblink_security_check(PGconn *conn, remoteConn *rconn, const char *connstr);
static void dblink_res_error(PGconn *conn, const char *conname, PGresult *res,
bool fail, const char *fmt,...) pg_attribute_printf(5, 6);
static char *get_connect_string(const char *servername);
static char *escape_param_str(const char *str);
static void validate_pkattnums(Relation rel,
int2vector *pkattnums_arg, int32 pknumatts_arg,
int **pkattnums, int *pknumatts);
static bool is_valid_dblink_option(const PQconninfoOption *options,
const char *option, Oid context);
static int applyRemoteGucs(PGconn *conn);
static void restoreLocalGucs(int nestlevel);
/* Global */
static remoteConn *pconn = NULL;
static HTAB *remoteConnHash = NULL;
/* custom wait event values, retrieved from shared memory */
static uint32 dblink_we_connect = 0;
static uint32 dblink_we_get_conn = 0;
static uint32 dblink_we_get_result = 0;
/*
* Following is list that holds multiple remote connections.
* Calling convention of each dblink function changes to accept
* connection name as the first parameter. The connection list is
* much like ecpg e.g. a mapping between a name and a PGconn object.
*/
typedef struct remoteConnHashEnt
{
char name[NAMEDATALEN];
remoteConn *rconn;
} remoteConnHashEnt;
/* initial number of connection hashes */
#define NUMCONN 16
static char *
xpstrdup(const char *in)
{
if (in == NULL)
return NULL;
return pstrdup(in);
}
static void
pg_attribute_noreturn()
dblink_res_internalerror(PGconn *conn, PGresult *res, const char *p2)
{
char *msg = pchomp(PQerrorMessage(conn));
PQclear(res);
elog(ERROR, "%s: %s", p2, msg);
}
static void
pg_attribute_noreturn()
dblink_conn_not_avail(const char *conname)
{
if (conname)
ereport(ERROR,
(errcode(ERRCODE_CONNECTION_DOES_NOT_EXIST),
errmsg("connection \"%s\" not available", conname)));
else
ereport(ERROR,
(errcode(ERRCODE_CONNECTION_DOES_NOT_EXIST),
errmsg("connection not available")));
}
static void
dblink_get_conn(char *conname_or_str,
PGconn *volatile *conn_p, char **conname_p, volatile bool *freeconn_p)
{
remoteConn *rconn = getConnectionByName(conname_or_str);
PGconn *conn;
char *conname;
bool freeconn;
if (rconn)
{
conn = rconn->conn;
conname = conname_or_str;
freeconn = false;
}
else
{
const char *connstr;
connstr = get_connect_string(conname_or_str);
if (connstr == NULL)
connstr = conname_or_str;
dblink_connstr_check(connstr);
/* first time, allocate or get the custom wait event */
if (dblink_we_get_conn == 0)
dblink_we_get_conn = WaitEventExtensionNew("DblinkGetConnect");
/* OK to make connection */
conn = libpqsrv_connect(connstr, dblink_we_get_conn);
if (PQstatus(conn) == CONNECTION_BAD)
{
char *msg = pchomp(PQerrorMessage(conn));
libpqsrv_disconnect(conn);
ereport(ERROR,
(errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION),
errmsg("could not establish connection"),
errdetail_internal("%s", msg)));
}
dblink_security_check(conn, rconn, connstr);
if (PQclientEncoding(conn) != GetDatabaseEncoding())
PQsetClientEncoding(conn, GetDatabaseEncodingName());
freeconn = true;
conname = NULL;
}
*conn_p = conn;
*conname_p = conname;
*freeconn_p = freeconn;
}
static PGconn *
dblink_get_named_conn(const char *conname)
{
remoteConn *rconn = getConnectionByName(conname);
if (rconn)
return rconn->conn;
dblink_conn_not_avail(conname);
return NULL; /* keep compiler quiet */
}
static void
dblink_init(void)
{
if (!pconn)
{
if (dblink_we_get_result == 0)
dblink_we_get_result = WaitEventExtensionNew("DblinkGetResult");
pconn = (remoteConn *) MemoryContextAlloc(TopMemoryContext, sizeof(remoteConn));
pconn->conn = NULL;
pconn->openCursorCount = 0;
pconn->newXactForCursor = false;
}
}
/*
* Create a persistent connection to another database
*/
PG_FUNCTION_INFO_V1(dblink_connect);
Datum
dblink_connect(PG_FUNCTION_ARGS)
{
char *conname_or_str = NULL;
char *connstr = NULL;
char *connname = NULL;
char *msg;
PGconn *conn = NULL;
remoteConn *rconn = NULL;
dblink_init();
if (PG_NARGS() == 2)
{
conname_or_str = text_to_cstring(PG_GETARG_TEXT_PP(1));
connname = text_to_cstring(PG_GETARG_TEXT_PP(0));
}
else if (PG_NARGS() == 1)
conname_or_str = text_to_cstring(PG_GETARG_TEXT_PP(0));
if (connname)
{
rconn = (remoteConn *) MemoryContextAlloc(TopMemoryContext,
sizeof(remoteConn));
rconn->conn = NULL;
rconn->openCursorCount = 0;
rconn->newXactForCursor = false;
}
/* first check for valid foreign data server */
connstr = get_connect_string(conname_or_str);
if (connstr == NULL)
connstr = conname_or_str;
/* check password in connection string if not superuser */
dblink_connstr_check(connstr);
/* first time, allocate or get the custom wait event */
if (dblink_we_connect == 0)
dblink_we_connect = WaitEventExtensionNew("DblinkConnect");
/* OK to make connection */
conn = libpqsrv_connect(connstr, dblink_we_connect);
if (PQstatus(conn) == CONNECTION_BAD)
{
msg = pchomp(PQerrorMessage(conn));
libpqsrv_disconnect(conn);
if (rconn)
pfree(rconn);
ereport(ERROR,
(errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION),
errmsg("could not establish connection"),
errdetail_internal("%s", msg)));
}
/* check password actually used if not superuser */
dblink_security_check(conn, rconn, connstr);
/* attempt to set client encoding to match server encoding, if needed */
if (PQclientEncoding(conn) != GetDatabaseEncoding())
PQsetClientEncoding(conn, GetDatabaseEncodingName());
if (connname)
{
rconn->conn = conn;
createNewConnection(connname, rconn);
}
else
{
if (pconn->conn)
libpqsrv_disconnect(pconn->conn);
pconn->conn = conn;
}
PG_RETURN_TEXT_P(cstring_to_text("OK"));
}
/*
* Clear a persistent connection to another database
*/
PG_FUNCTION_INFO_V1(dblink_disconnect);
Datum
dblink_disconnect(PG_FUNCTION_ARGS)
{
char *conname = NULL;
remoteConn *rconn = NULL;
PGconn *conn = NULL;
dblink_init();
if (PG_NARGS() == 1)
{
conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
rconn = getConnectionByName(conname);
if (rconn)
conn = rconn->conn;
}
else
conn = pconn->conn;
if (!conn)
dblink_conn_not_avail(conname);
libpqsrv_disconnect(conn);
if (rconn)
{
deleteConnection(conname);
pfree(rconn);
}
else
pconn->conn = NULL;
PG_RETURN_TEXT_P(cstring_to_text("OK"));
}
/*
* opens a cursor using a persistent connection
*/
PG_FUNCTION_INFO_V1(dblink_open);
Datum
dblink_open(PG_FUNCTION_ARGS)
{
PGresult *res = NULL;
PGconn *conn;
char *curname = NULL;
char *sql = NULL;
char *conname = NULL;
StringInfoData buf;
remoteConn *rconn = NULL;
bool fail = true; /* default to backward compatible behavior */
dblink_init();
initStringInfo(&buf);
if (PG_NARGS() == 2)
{
/* text,text */
curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
sql = text_to_cstring(PG_GETARG_TEXT_PP(1));
rconn = pconn;
}
else if (PG_NARGS() == 3)
{
/* might be text,text,text or text,text,bool */
if (get_fn_expr_argtype(fcinfo->flinfo, 2) == BOOLOID)
{
curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
sql = text_to_cstring(PG_GETARG_TEXT_PP(1));
fail = PG_GETARG_BOOL(2);
rconn = pconn;
}
else
{
conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
sql = text_to_cstring(PG_GETARG_TEXT_PP(2));
rconn = getConnectionByName(conname);
}
}
else if (PG_NARGS() == 4)
{
/* text,text,text,bool */
conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
sql = text_to_cstring(PG_GETARG_TEXT_PP(2));
fail = PG_GETARG_BOOL(3);
rconn = getConnectionByName(conname);
}
if (!rconn || !rconn->conn)
dblink_conn_not_avail(conname);
conn = rconn->conn;
/* If we are not in a transaction, start one */
if (PQtransactionStatus(conn) == PQTRANS_IDLE)
{
res = libpqsrv_exec(conn, "BEGIN", dblink_we_get_result);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
dblink_res_internalerror(conn, res, "begin error");
PQclear(res);
rconn->newXactForCursor = true;
/*
* Since transaction state was IDLE, we force cursor count to
* initially be 0. This is needed as a previous ABORT might have wiped
* out our transaction without maintaining the cursor count for us.
*/
rconn->openCursorCount = 0;
}
/* if we started a transaction, increment cursor count */
if (rconn->newXactForCursor)
(rconn->openCursorCount)++;
appendStringInfo(&buf, "DECLARE %s CURSOR FOR %s", curname, sql);
res = libpqsrv_exec(conn, buf.data, dblink_we_get_result);
if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
{
dblink_res_error(conn, conname, res, fail,
"while opening cursor \"%s\"", curname);
PG_RETURN_TEXT_P(cstring_to_text("ERROR"));
}
PQclear(res);
PG_RETURN_TEXT_P(cstring_to_text("OK"));
}
/*
* closes a cursor
*/
PG_FUNCTION_INFO_V1(dblink_close);
Datum
dblink_close(PG_FUNCTION_ARGS)
{
PGconn *conn;
PGresult *res = NULL;
char *curname = NULL;
char *conname = NULL;
StringInfoData buf;
remoteConn *rconn = NULL;
bool fail = true; /* default to backward compatible behavior */
dblink_init();
initStringInfo(&buf);
if (PG_NARGS() == 1)
{
/* text */
curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
rconn = pconn;
}
else if (PG_NARGS() == 2)
{
/* might be text,text or text,bool */
if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
{
curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
fail = PG_GETARG_BOOL(1);
rconn = pconn;
}
else
{
conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
rconn = getConnectionByName(conname);
}
}
if (PG_NARGS() == 3)
{
/* text,text,bool */
conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
fail = PG_GETARG_BOOL(2);
rconn = getConnectionByName(conname);
}
if (!rconn || !rconn->conn)
dblink_conn_not_avail(conname);
conn = rconn->conn;
appendStringInfo(&buf, "CLOSE %s", curname);
/* close the cursor */
res = libpqsrv_exec(conn, buf.data, dblink_we_get_result);
if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
{
dblink_res_error(conn, conname, res, fail,
"while closing cursor \"%s\"", curname);
PG_RETURN_TEXT_P(cstring_to_text("ERROR"));
}
PQclear(res);
/* if we started a transaction, decrement cursor count */
if (rconn->newXactForCursor)
{
(rconn->openCursorCount)--;
/* if count is zero, commit the transaction */
if (rconn->openCursorCount == 0)
{
rconn->newXactForCursor = false;
res = libpqsrv_exec(conn, "COMMIT", dblink_we_get_result);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
dblink_res_internalerror(conn, res, "commit error");
PQclear(res);
}
}
PG_RETURN_TEXT_P(cstring_to_text("OK"));
}
/*
* Fetch results from an open cursor
*/
PG_FUNCTION_INFO_V1(dblink_fetch);
Datum
dblink_fetch(PG_FUNCTION_ARGS)
{
PGresult *res = NULL;
char *conname = NULL;
remoteConn *rconn = NULL;
PGconn *conn = NULL;
StringInfoData buf;
char *curname = NULL;
int howmany = 0;
bool fail = true; /* default to backward compatible */
prepTuplestoreResult(fcinfo);
dblink_init();
if (PG_NARGS() == 4)
{
/* text,text,int,bool */
conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
howmany = PG_GETARG_INT32(2);
fail = PG_GETARG_BOOL(3);
rconn = getConnectionByName(conname);
if (rconn)
conn = rconn->conn;
}
else if (PG_NARGS() == 3)
{
/* text,text,int or text,int,bool */
if (get_fn_expr_argtype(fcinfo->flinfo, 2) == BOOLOID)
{
curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
howmany = PG_GETARG_INT32(1);
fail = PG_GETARG_BOOL(2);
conn = pconn->conn;
}
else
{
conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
howmany = PG_GETARG_INT32(2);
rconn = getConnectionByName(conname);
if (rconn)
conn = rconn->conn;
}
}
else if (PG_NARGS() == 2)
{
/* text,int */
curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
howmany = PG_GETARG_INT32(1);
conn = pconn->conn;
}
if (!conn)
dblink_conn_not_avail(conname);
initStringInfo(&buf);
appendStringInfo(&buf, "FETCH %d FROM %s", howmany, curname);
/*
* Try to execute the query. Note that since libpq uses malloc, the
* PGresult will be long-lived even though we are still in a short-lived
* memory context.
*/
res = libpqsrv_exec(conn, buf.data, dblink_we_get_result);
if (!res ||
(PQresultStatus(res) != PGRES_COMMAND_OK &&
PQresultStatus(res) != PGRES_TUPLES_OK))
{
dblink_res_error(conn, conname, res, fail,
"while fetching from cursor \"%s\"", curname);
return (Datum) 0;
}
else if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
/* cursor does not exist - closed already or bad name */
PQclear(res);
ereport(ERROR,
(errcode(ERRCODE_INVALID_CURSOR_NAME),
errmsg("cursor \"%s\" does not exist", curname)));
}
materializeResult(fcinfo, conn, res);
return (Datum) 0;
}
/*
* Note: this is the new preferred version of dblink
*/
PG_FUNCTION_INFO_V1(dblink_record);
Datum
dblink_record(PG_FUNCTION_ARGS)
{
return dblink_record_internal(fcinfo, false);
}
PG_FUNCTION_INFO_V1(dblink_send_query);
Datum
dblink_send_query(PG_FUNCTION_ARGS)
{
PGconn *conn;
char *sql;
int retval;
if (PG_NARGS() == 2)
{
conn = dblink_get_named_conn(text_to_cstring(PG_GETARG_TEXT_PP(0)));
sql = text_to_cstring(PG_GETARG_TEXT_PP(1));
}
else
/* shouldn't happen */
elog(ERROR, "wrong number of arguments");
/* async query send */
retval = PQsendQuery(conn, sql);
if (retval != 1)
elog(NOTICE, "could not send query: %s", pchomp(PQerrorMessage(conn)));
PG_RETURN_INT32(retval);
}
PG_FUNCTION_INFO_V1(dblink_get_result);
Datum
dblink_get_result(PG_FUNCTION_ARGS)
{
return dblink_record_internal(fcinfo, true);
}
static Datum
dblink_record_internal(FunctionCallInfo fcinfo, bool is_async)
{
PGconn *volatile conn = NULL;
volatile bool freeconn = false;
prepTuplestoreResult(fcinfo);
dblink_init();
PG_TRY();
{
char *sql = NULL;
char *conname = NULL;
bool fail = true; /* default to backward compatible */
if (!is_async)
{
if (PG_NARGS() == 3)
{
/* text,text,bool */
conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
sql = text_to_cstring(PG_GETARG_TEXT_PP(1));
fail = PG_GETARG_BOOL(2);
dblink_get_conn(conname, &conn, &conname, &freeconn);
}
else if (PG_NARGS() == 2)
{
/* text,text or text,bool */
if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
{
sql = text_to_cstring(PG_GETARG_TEXT_PP(0));
fail = PG_GETARG_BOOL(1);
conn = pconn->conn;
}
else
{
conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
sql = text_to_cstring(PG_GETARG_TEXT_PP(1));
dblink_get_conn(conname, &conn, &conname, &freeconn);
}
}
else if (PG_NARGS() == 1)
{
/* text */
conn = pconn->conn;
sql = text_to_cstring(PG_GETARG_TEXT_PP(0));
}
else
/* shouldn't happen */
elog(ERROR, "wrong number of arguments");
}
else /* is_async */
{
/* get async result */
conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
if (PG_NARGS() == 2)
{
/* text,bool */
fail = PG_GETARG_BOOL(1);
conn = dblink_get_named_conn(conname);
}
else if (PG_NARGS() == 1)
{
/* text */
conn = dblink_get_named_conn(conname);
}
else
/* shouldn't happen */
elog(ERROR, "wrong number of arguments");
}
if (!conn)
dblink_conn_not_avail(conname);
if (!is_async)
{
/* synchronous query, use efficient tuple collection method */
materializeQueryResult(fcinfo, conn, conname, sql, fail);
}
else
{
/* async result retrieval, do it the old way */
PGresult *res = libpqsrv_get_result(conn, dblink_we_get_result);
/* NULL means we're all done with the async results */
if (res)
{
if (PQresultStatus(res) != PGRES_COMMAND_OK &&
PQresultStatus(res) != PGRES_TUPLES_OK)
{
dblink_res_error(conn, conname, res, fail,
"while executing query");
/* if fail isn't set, we'll return an empty query result */
}
else
{
materializeResult(fcinfo, conn, res);
}
}
}
}
PG_FINALLY();
{
/* if needed, close the connection to the database */
if (freeconn)
libpqsrv_disconnect(conn);
}
PG_END_TRY();
return (Datum) 0;
}
/*
* Verify function caller can handle a tuplestore result, and set up for that.
*
* Note: if the caller returns without actually creating a tuplestore, the
* executor will treat the function result as an empty set.
*/
static void
prepTuplestoreResult(FunctionCallInfo fcinfo)
{
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
/* check to see if query supports us returning a tuplestore */
if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("set-valued function called in context that cannot accept a set")));
if (!(rsinfo->allowedModes & SFRM_Materialize))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("materialize mode required, but it is not allowed in this context")));
/* let the executor know we're sending back a tuplestore */
rsinfo->returnMode = SFRM_Materialize;
/* caller must fill these to return a non-empty result */
rsinfo->setResult = NULL;
rsinfo->setDesc = NULL;
}
/*
* Copy the contents of the PGresult into a tuplestore to be returned
* as the result of the current function.
* The PGresult will be released in this function.
*/
static void
materializeResult(FunctionCallInfo fcinfo, PGconn *conn, PGresult *res)
{
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
/* prepTuplestoreResult must have been called previously */
Assert(rsinfo->returnMode == SFRM_Materialize);
PG_TRY();
{
TupleDesc tupdesc;
bool is_sql_cmd;
int ntuples;
int nfields;
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
is_sql_cmd = true;
/*
* need a tuple descriptor representing one TEXT column to return
* the command status string as our result tuple
*/
tupdesc = CreateTemplateTupleDesc(1);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
TEXTOID, -1, 0);
ntuples = 1;
nfields = 1;
}
else
{
Assert(PQresultStatus(res) == PGRES_TUPLES_OK);
is_sql_cmd = false;
/* get a tuple descriptor for our result type */
switch (get_call_result_type(fcinfo, NULL, &tupdesc))
{
case TYPEFUNC_COMPOSITE:
/* success */
break;
case TYPEFUNC_RECORD:
/* failed to determine actual type of RECORD */
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("function returning record called in context "
"that cannot accept type record")));
break;
default:
/* result type isn't composite */
elog(ERROR, "return type must be a row type");
break;
}
/* make sure we have a persistent copy of the tupdesc */
tupdesc = CreateTupleDescCopy(tupdesc);
ntuples = PQntuples(res);
nfields = PQnfields(res);
}
/*
* check result and tuple descriptor have the same number of columns
*/
if (nfields != tupdesc->natts)
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("remote query result rowtype does not match "
"the specified FROM clause rowtype")));
if (ntuples > 0)
{
AttInMetadata *attinmeta;
int nestlevel = -1;
Tuplestorestate *tupstore;
MemoryContext oldcontext;
int row;
char **values;
attinmeta = TupleDescGetAttInMetadata(tupdesc);
/* Set GUCs to ensure we read GUC-sensitive data types correctly */
if (!is_sql_cmd)
nestlevel = applyRemoteGucs(conn);
oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
tupstore = tuplestore_begin_heap(true, false, work_mem);
rsinfo->setResult = tupstore;
rsinfo->setDesc = tupdesc;
MemoryContextSwitchTo(oldcontext);
values = palloc_array(char *, nfields);
/* put all tuples into the tuplestore */
for (row = 0; row < ntuples; row++)
{
HeapTuple tuple;
if (!is_sql_cmd)
{
int i;
for (i = 0; i < nfields; i++)
{
if (PQgetisnull(res, row, i))
values[i] = NULL;
else
values[i] = PQgetvalue(res, row, i);
}
}
else
{
values[0] = PQcmdStatus(res);
}
/* build the tuple and put it into the tuplestore. */
tuple = BuildTupleFromCStrings(attinmeta, values);
tuplestore_puttuple(tupstore, tuple);
}
/* clean up GUC settings, if we changed any */
restoreLocalGucs(nestlevel);
}
}
PG_FINALLY();
{
/* be sure to release the libpq result */
PQclear(res);
}
PG_END_TRY();
}
/*
* Execute the given SQL command and store its results into a tuplestore
* to be returned as the result of the current function.
*
* This is equivalent to PQexec followed by materializeResult, but we make
* use of libpq's single-row mode to avoid accumulating the whole result
* inside libpq before it gets transferred to the tuplestore.
*/
static void
materializeQueryResult(FunctionCallInfo fcinfo,
PGconn *conn,
const char *conname,
const char *sql,
bool fail)
{
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
PGresult *volatile res = NULL;
volatile storeInfo sinfo = {0};
/* prepTuplestoreResult must have been called previously */
Assert(rsinfo->returnMode == SFRM_Materialize);
sinfo.fcinfo = fcinfo;
PG_TRY();
{
/* Create short-lived memory context for data conversions */
sinfo.tmpcontext = AllocSetContextCreate(CurrentMemoryContext,
"dblink temporary context",
ALLOCSET_DEFAULT_SIZES);
/* execute query, collecting any tuples into the tuplestore */
res = storeQueryResult(&sinfo, conn, sql);
if (!res ||
(PQresultStatus(res) != PGRES_COMMAND_OK &&
PQresultStatus(res) != PGRES_TUPLES_OK))
{
/*
* dblink_res_error will clear the passed PGresult, so we need
* this ugly dance to avoid doing so twice during error exit
*/
PGresult *res1 = res;
res = NULL;
dblink_res_error(conn, conname, res1, fail,
"while executing query");
/* if fail isn't set, we'll return an empty query result */
}
else if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
/*
* storeRow didn't get called, so we need to convert the command
* status string to a tuple manually
*/
TupleDesc tupdesc;
AttInMetadata *attinmeta;
Tuplestorestate *tupstore;
HeapTuple tuple;
char *values[1];
MemoryContext oldcontext;
/*
* need a tuple descriptor representing one TEXT column to return
* the command status string as our result tuple
*/
tupdesc = CreateTemplateTupleDesc(1);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
TEXTOID, -1, 0);
attinmeta = TupleDescGetAttInMetadata(tupdesc);
oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
tupstore = tuplestore_begin_heap(true, false, work_mem);
rsinfo->setResult = tupstore;
rsinfo->setDesc = tupdesc;
MemoryContextSwitchTo(oldcontext);
values[0] = PQcmdStatus(res);
/* build the tuple and put it into the tuplestore. */
tuple = BuildTupleFromCStrings(attinmeta, values);
tuplestore_puttuple(tupstore, tuple);
PQclear(res);
res = NULL;
}
else
{
Assert(PQresultStatus(res) == PGRES_TUPLES_OK);
/* storeRow should have created a tuplestore */
Assert(rsinfo->setResult != NULL);
PQclear(res);
res = NULL;
}
/* clean up data conversion short-lived memory context */
if (sinfo.tmpcontext != NULL)
MemoryContextDelete(sinfo.tmpcontext);
sinfo.tmpcontext = NULL;
PQclear(sinfo.last_res);
sinfo.last_res = NULL;
PQclear(sinfo.cur_res);
sinfo.cur_res = NULL;
}
PG_CATCH();
{
/* be sure to release any libpq result we collected */
PQclear(res);
PQclear(sinfo.last_res);
PQclear(sinfo.cur_res);
/* and clear out any pending data in libpq */
while ((res = libpqsrv_get_result(conn, dblink_we_get_result)) !=
NULL)
PQclear(res);
PG_RE_THROW();
}
PG_END_TRY();
}
/*
* Execute query, and send any result rows to sinfo->tuplestore.
*/
static PGresult *
storeQueryResult(volatile storeInfo *sinfo, PGconn *conn, const char *sql)
{
bool first = true;
int nestlevel = -1;
PGresult *res;
if (!PQsendQuery(conn, sql))
elog(ERROR, "could not send query: %s", pchomp(PQerrorMessage(conn)));
if (!PQsetSingleRowMode(conn)) /* shouldn't fail */
elog(ERROR, "failed to set single-row mode for dblink query");
for (;;)
{
CHECK_FOR_INTERRUPTS();
sinfo->cur_res = libpqsrv_get_result(conn, dblink_we_get_result);
if (!sinfo->cur_res)
break;
if (PQresultStatus(sinfo->cur_res) == PGRES_SINGLE_TUPLE)
{
/* got one row from possibly-bigger resultset */
/*
* Set GUCs to ensure we read GUC-sensitive data types correctly.
* We shouldn't do this until we have a row in hand, to ensure
* libpq has seen any earlier ParameterStatus protocol messages.
*/
if (first && nestlevel < 0)
nestlevel = applyRemoteGucs(conn);
storeRow(sinfo, sinfo->cur_res, first);
PQclear(sinfo->cur_res);
sinfo->cur_res = NULL;
first = false;
}
else
{
/* if empty resultset, fill tuplestore header */
if (first && PQresultStatus(sinfo->cur_res) == PGRES_TUPLES_OK)
storeRow(sinfo, sinfo->cur_res, first);
/* store completed result at last_res */
PQclear(sinfo->last_res);
sinfo->last_res = sinfo->cur_res;
sinfo->cur_res = NULL;
first = true;
}
}
/* clean up GUC settings, if we changed any */
restoreLocalGucs(nestlevel);
/* return last_res */
res = sinfo->last_res;
sinfo->last_res = NULL;
return res;
}
/*
* Send single row to sinfo->tuplestore.
*
* If "first" is true, create the tuplestore using PGresult's metadata
* (in this case the PGresult might contain either zero or one row).
*/
static void
storeRow(volatile storeInfo *sinfo, PGresult *res, bool first)
{
int nfields = PQnfields(res);
HeapTuple tuple;
int i;
MemoryContext oldcontext;
if (first)
{
/* Prepare for new result set */
ReturnSetInfo *rsinfo = (ReturnSetInfo *) sinfo->fcinfo->resultinfo;
TupleDesc tupdesc;
/*
* It's possible to get more than one result set if the query string
* contained multiple SQL commands. In that case, we follow PQexec's
* traditional behavior of throwing away all but the last result.
*/
if (sinfo->tuplestore)
tuplestore_end(sinfo->tuplestore);
sinfo->tuplestore = NULL;
/* get a tuple descriptor for our result type */
switch (get_call_result_type(sinfo->fcinfo, NULL, &tupdesc))
{
case TYPEFUNC_COMPOSITE:
/* success */
break;
case TYPEFUNC_RECORD:
/* failed to determine actual type of RECORD */
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("function returning record called in context "
"that cannot accept type record")));
break;
default:
/* result type isn't composite */
elog(ERROR, "return type must be a row type");
break;
}
/* make sure we have a persistent copy of the tupdesc */
tupdesc = CreateTupleDescCopy(tupdesc);
/* check result and tuple descriptor have the same number of columns */
if (nfields != tupdesc->natts)
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("remote query result rowtype does not match "
"the specified FROM clause rowtype")));
/* Prepare attinmeta for later data conversions */
sinfo->attinmeta = TupleDescGetAttInMetadata(tupdesc);
/* Create a new, empty tuplestore */
oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
sinfo->tuplestore = tuplestore_begin_heap(true, false, work_mem);
rsinfo->setResult = sinfo->tuplestore;
rsinfo->setDesc = tupdesc;
MemoryContextSwitchTo(oldcontext);
/* Done if empty resultset */
if (PQntuples(res) == 0)
return;
/*
* Set up sufficiently-wide string pointers array; this won't change
* in size so it's easy to preallocate.
*/
if (sinfo->cstrs)
pfree(sinfo->cstrs);
sinfo->cstrs = palloc_array(char *, nfields);
}
/* Should have a single-row result if we get here */
Assert(PQntuples(res) == 1);
/*
* Do the following work in a temp context that we reset after each tuple.
* This cleans up not only the data we have direct access to, but any
* cruft the I/O functions might leak.
*/
oldcontext = MemoryContextSwitchTo(sinfo->tmpcontext);
/*
* Fill cstrs with null-terminated strings of column values.
*/
for (i = 0; i < nfields; i++)
{
if (PQgetisnull(res, 0, i))
sinfo->cstrs[i] = NULL;
else
sinfo->cstrs[i] = PQgetvalue(res, 0, i);
}
/* Convert row to a tuple, and add it to the tuplestore */
tuple = BuildTupleFromCStrings(sinfo->attinmeta, sinfo->cstrs);
tuplestore_puttuple(sinfo->tuplestore, tuple);
/* Clean up */
MemoryContextSwitchTo(oldcontext);
MemoryContextReset(sinfo->tmpcontext);
}
/*
* List all open dblink connections by name.
* Returns an array of all connection names.
* Takes no params
*/
PG_FUNCTION_INFO_V1(dblink_get_connections);
Datum
dblink_get_connections(PG_FUNCTION_ARGS)
{
HASH_SEQ_STATUS status;
remoteConnHashEnt *hentry;
ArrayBuildState *astate = NULL;
if (remoteConnHash)
{
hash_seq_init(&status, remoteConnHash);
while ((hentry = (remoteConnHashEnt *) hash_seq_search(&status)) != NULL)
{
/* stash away current value */
astate = accumArrayResult(astate,
CStringGetTextDatum(hentry->name),
false, TEXTOID, CurrentMemoryContext);
}
}
if (astate)
PG_RETURN_DATUM(makeArrayResult(astate,
CurrentMemoryContext));
else
PG_RETURN_NULL();
}
/*
* Checks if a given remote connection is busy
*
* Returns 1 if the connection is busy, 0 otherwise
* Params:
* text connection_name - name of the connection to check
*
*/
PG_FUNCTION_INFO_V1(dblink_is_busy);
Datum
dblink_is_busy(PG_FUNCTION_ARGS)
{
PGconn *conn;
dblink_init();
conn = dblink_get_named_conn(text_to_cstring(PG_GETARG_TEXT_PP(0)));
PQconsumeInput(conn);
PG_RETURN_INT32(PQisBusy(conn));
}
/*
* Cancels a running request on a connection
*
* Returns text:
* "OK" if the cancel request has been sent correctly,
* an error message otherwise
*
* Params:
* text connection_name - name of the connection to check
*
*/
PG_FUNCTION_INFO_V1(dblink_cancel_query);
Datum
dblink_cancel_query(PG_FUNCTION_ARGS)
{
PGconn *conn;
char *msg;
TimestampTz endtime;
dblink_init();
conn = dblink_get_named_conn(text_to_cstring(PG_GETARG_TEXT_PP(0)));
endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
30000);
msg = libpqsrv_cancel(conn, endtime);
if (msg == NULL)
msg = "OK";
PG_RETURN_TEXT_P(cstring_to_text(msg));
}
/*
* Get error message from a connection
*
* Returns text:
* "OK" if no error, an error message otherwise
*
* Params:
* text connection_name - name of the connection to check
*
*/
PG_FUNCTION_INFO_V1(dblink_error_message);
Datum
dblink_error_message(PG_FUNCTION_ARGS)
{
char *msg;
PGconn *conn;
dblink_init();
conn = dblink_get_named_conn(text_to_cstring(PG_GETARG_TEXT_PP(0)));
msg = PQerrorMessage(conn);
if (msg == NULL || msg[0] == '\0')
PG_RETURN_TEXT_P(cstring_to_text("OK"));
else
PG_RETURN_TEXT_P(cstring_to_text(pchomp(msg)));
}
/*
* Execute an SQL non-SELECT command
*/
PG_FUNCTION_INFO_V1(dblink_exec);
Datum
dblink_exec(PG_FUNCTION_ARGS)
{
text *volatile sql_cmd_status = NULL;
PGconn *volatile conn = NULL;
volatile bool freeconn = false;
dblink_init();
PG_TRY();
{
PGresult *res = NULL;
char *sql = NULL;
char *conname = NULL;
bool fail = true; /* default to backward compatible behavior */
if (PG_NARGS() == 3)
{
/* must be text,text,bool */
conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
sql = text_to_cstring(PG_GETARG_TEXT_PP(1));
fail = PG_GETARG_BOOL(2);
dblink_get_conn(conname, &conn, &conname, &freeconn);
}
else if (PG_NARGS() == 2)
{
/* might be text,text or text,bool */
if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
{
sql = text_to_cstring(PG_GETARG_TEXT_PP(0));
fail = PG_GETARG_BOOL(1);
conn = pconn->conn;
}
else
{
conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
sql = text_to_cstring(PG_GETARG_TEXT_PP(1));
dblink_get_conn(conname, &conn, &conname, &freeconn);
}
}
else if (PG_NARGS() == 1)
{
/* must be single text argument */
conn = pconn->conn;
sql = text_to_cstring(PG_GETARG_TEXT_PP(0));
}
else
/* shouldn't happen */
elog(ERROR, "wrong number of arguments");
if (!conn)
dblink_conn_not_avail(conname);
res = libpqsrv_exec(conn, sql, dblink_we_get_result);
if (!res ||
(PQresultStatus(res) != PGRES_COMMAND_OK &&
PQresultStatus(res) != PGRES_TUPLES_OK))
{
dblink_res_error(conn, conname, res, fail,
"while executing command");
/*
* and save a copy of the command status string to return as our
* result tuple
*/
sql_cmd_status = cstring_to_text("ERROR");
}
else if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
/*
* and save a copy of the command status string to return as our
* result tuple
*/
sql_cmd_status = cstring_to_text(PQcmdStatus(res));
PQclear(res);
}
else
{
PQclear(res);
ereport(ERROR,
(errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
errmsg("statement returning results not allowed")));
}
}
PG_FINALLY();
{
/* if needed, close the connection to the database */
if (freeconn)
libpqsrv_disconnect(conn);
}
PG_END_TRY();
PG_RETURN_TEXT_P(sql_cmd_status);
}
/*
* dblink_get_pkey
*
* Return list of primary key fields for the supplied relation,
* or NULL if none exists.
*/
PG_FUNCTION_INFO_V1(dblink_get_pkey);
Datum
dblink_get_pkey(PG_FUNCTION_ARGS)
{
int16 indnkeyatts;
char **results;
FuncCallContext *funcctx;
int32 call_cntr;
int32 max_calls;
AttInMetadata *attinmeta;
MemoryContext oldcontext;
/* stuff done only on the first call of the function */
if (SRF_IS_FIRSTCALL())
{
Relation rel;
TupleDesc tupdesc;
/* create a function context for cross-call persistence */
funcctx = SRF_FIRSTCALL_INIT();
/*
* switch to memory context appropriate for multiple function calls
*/
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
/* open target relation */
rel = get_rel_from_relname(PG_GETARG_TEXT_PP(0), AccessShareLock, ACL_SELECT);
/* get the array of attnums */
results = get_pkey_attnames(rel, &indnkeyatts);
relation_close(rel, AccessShareLock);
/*
* need a tuple descriptor representing one INT and one TEXT column
*/
tupdesc = CreateTemplateTupleDesc(2);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "position",
INT4OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "colname",
TEXTOID, -1, 0);
/*
* Generate attribute metadata needed later to produce tuples from raw
* C strings
*/
attinmeta = TupleDescGetAttInMetadata(tupdesc);
funcctx->attinmeta = attinmeta;
if ((results != NULL) && (indnkeyatts > 0))
{
funcctx->max_calls = indnkeyatts;
/* got results, keep track of them */
funcctx->user_fctx = results;
}
else
{
/* fast track when no results */
MemoryContextSwitchTo(oldcontext);
SRF_RETURN_DONE(funcctx);
}
MemoryContextSwitchTo(oldcontext);
}
/* stuff done on every call of the function */
funcctx = SRF_PERCALL_SETUP();
/*
* initialize per-call variables
*/
call_cntr = funcctx->call_cntr;
max_calls = funcctx->max_calls;
results = (char **) funcctx->user_fctx;
attinmeta = funcctx->attinmeta;
if (call_cntr < max_calls) /* do when there is more left to send */
{
char **values;
HeapTuple tuple;
Datum result;
values = palloc_array(char *, 2);
values[0] = psprintf("%d", call_cntr + 1);
values[1] = results[call_cntr];
/* build the tuple */
tuple = BuildTupleFromCStrings(attinmeta, values);
/* make the tuple into a datum */
result = HeapTupleGetDatum(tuple);
SRF_RETURN_NEXT(funcctx, result);
}
else
{
/* do when there is no more left */
SRF_RETURN_DONE(funcctx);
}
}
/*
* dblink_build_sql_insert
*
* Used to generate an SQL insert statement
* based on an existing tuple in a local relation.
* This is useful for selectively replicating data
* to another server via dblink.
*
* API:
* <relname> - name of local table of interest
* <pkattnums> - an int2vector of attnums which will be used
* to identify the local tuple of interest
* <pknumatts> - number of attnums in pkattnums
* <src_pkattvals_arry> - text array of key values which will be used
* to identify the local tuple of interest
* <tgt_pkattvals_arry> - text array of key values which will be used
* to build the string for execution remotely. These are substituted
* for their counterparts in src_pkattvals_arry
*/
PG_FUNCTION_INFO_V1(dblink_build_sql_insert);
Datum
dblink_build_sql_insert(PG_FUNCTION_ARGS)
{
text *relname_text = PG_GETARG_TEXT_PP(0);
int2vector *pkattnums_arg = (int2vector *) PG_GETARG_POINTER(1);
int32 pknumatts_arg = PG_GETARG_INT32(2);
ArrayType *src_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(3);
ArrayType *tgt_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(4);
Relation rel;
int *pkattnums;
int pknumatts;
char **src_pkattvals;
char **tgt_pkattvals;
int src_nitems;
int tgt_nitems;
char *sql;
/*
* Open target relation.
*/
rel = get_rel_from_relname(relname_text, AccessShareLock, ACL_SELECT);
/*
* Process pkattnums argument.
*/
validate_pkattnums(rel, pkattnums_arg, pknumatts_arg,
&pkattnums, &pknumatts);
/*
* Source array is made up of key values that will be used to locate the
* tuple of interest from the local system.
*/
src_pkattvals = get_text_array_contents(src_pkattvals_arry, &src_nitems);
/*
* There should be one source array key value for each key attnum
*/
if (src_nitems != pknumatts)
ereport(ERROR,
(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
errmsg("source key array length must match number of key attributes")));
/*
* Target array is made up of key values that will be used to build the
* SQL string for use on the remote system.
*/
tgt_pkattvals = get_text_array_contents(tgt_pkattvals_arry, &tgt_nitems);
/*
* There should be one target array key value for each key attnum
*/
if (tgt_nitems != pknumatts)
ereport(ERROR,
(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
errmsg("target key array length must match number of key attributes")));
/*
* Prep work is finally done. Go get the SQL string.
*/
sql = get_sql_insert(rel, pkattnums, pknumatts, src_pkattvals, tgt_pkattvals);
/*
* Now we can close the relation.
*/
relation_close(rel, AccessShareLock);
/*
* And send it
*/
PG_RETURN_TEXT_P(cstring_to_text(sql));
}
/*
* dblink_build_sql_delete
*
* Used to generate an SQL delete statement.
* This is useful for selectively replicating a
* delete to another server via dblink.
*
* API:
* <relname> - name of remote table of interest
* <pkattnums> - an int2vector of attnums which will be used
* to identify the remote tuple of interest
* <pknumatts> - number of attnums in pkattnums
* <tgt_pkattvals_arry> - text array of key values which will be used
* to build the string for execution remotely.
*/
PG_FUNCTION_INFO_V1(dblink_build_sql_delete);
Datum
dblink_build_sql_delete(PG_FUNCTION_ARGS)
{
text *relname_text = PG_GETARG_TEXT_PP(0);
int2vector *pkattnums_arg = (int2vector *) PG_GETARG_POINTER(1);
int32 pknumatts_arg = PG_GETARG_INT32(2);
ArrayType *tgt_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(3);
Relation rel;
int *pkattnums;
int pknumatts;
char **tgt_pkattvals;
int tgt_nitems;
char *sql;
/*
* Open target relation.
*/
rel = get_rel_from_relname(relname_text, AccessShareLock, ACL_SELECT);
/*
* Process pkattnums argument.
*/
validate_pkattnums(rel, pkattnums_arg, pknumatts_arg,
&pkattnums, &pknumatts);
/*
* Target array is made up of key values that will be used to build the
* SQL string for use on the remote system.
*/
tgt_pkattvals = get_text_array_contents(tgt_pkattvals_arry, &tgt_nitems);
/*
* There should be one target array key value for each key attnum
*/
if (tgt_nitems != pknumatts)
ereport(ERROR,
(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
errmsg("target key array length must match number of key attributes")));
/*
* Prep work is finally done. Go get the SQL string.
*/
sql = get_sql_delete(rel, pkattnums, pknumatts, tgt_pkattvals);
/*
* Now we can close the relation.
*/
relation_close(rel, AccessShareLock);
/*
* And send it
*/
PG_RETURN_TEXT_P(cstring_to_text(sql));
}
/*
* dblink_build_sql_update
*
* Used to generate an SQL update statement
* based on an existing tuple in a local relation.
* This is useful for selectively replicating data
* to another server via dblink.
*
* API:
* <relname> - name of local table of interest
* <pkattnums> - an int2vector of attnums which will be used
* to identify the local tuple of interest
* <pknumatts> - number of attnums in pkattnums
* <src_pkattvals_arry> - text array of key values which will be used
* to identify the local tuple of interest
* <tgt_pkattvals_arry> - text array of key values which will be used
* to build the string for execution remotely. These are substituted
* for their counterparts in src_pkattvals_arry
*/
PG_FUNCTION_INFO_V1(dblink_build_sql_update);
Datum
dblink_build_sql_update(PG_FUNCTION_ARGS)
{
text *relname_text = PG_GETARG_TEXT_PP(0);
int2vector *pkattnums_arg = (int2vector *) PG_GETARG_POINTER(1);
int32 pknumatts_arg = PG_GETARG_INT32(2);
ArrayType *src_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(3);
ArrayType *tgt_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(4);
Relation rel;
int *pkattnums;
int pknumatts;
char **src_pkattvals;
char **tgt_pkattvals;
int src_nitems;
int tgt_nitems;
char *sql;
/*
* Open target relation.
*/
rel = get_rel_from_relname(relname_text, AccessShareLock, ACL_SELECT);
/*
* Process pkattnums argument.
*/
validate_pkattnums(rel, pkattnums_arg, pknumatts_arg,
&pkattnums, &pknumatts);
/*
* Source array is made up of key values that will be used to locate the
* tuple of interest from the local system.
*/
src_pkattvals = get_text_array_contents(src_pkattvals_arry, &src_nitems);
/*
* There should be one source array key value for each key attnum
*/
if (src_nitems != pknumatts)
ereport(ERROR,
(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
errmsg("source key array length must match number of key attributes")));
/*
* Target array is made up of key values that will be used to build the
* SQL string for use on the remote system.
*/
tgt_pkattvals = get_text_array_contents(tgt_pkattvals_arry, &tgt_nitems);
/*
* There should be one target array key value for each key attnum
*/
if (tgt_nitems != pknumatts)
ereport(ERROR,
(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
errmsg("target key array length must match number of key attributes")));
/*
* Prep work is finally done. Go get the SQL string.
*/
sql = get_sql_update(rel, pkattnums, pknumatts, src_pkattvals, tgt_pkattvals);
/*
* Now we can close the relation.
*/
relation_close(rel, AccessShareLock);
/*
* And send it
*/
PG_RETURN_TEXT_P(cstring_to_text(sql));
}
/*
* dblink_current_query
* return the current query string
* to allow its use in (among other things)
* rewrite rules
*/
PG_FUNCTION_INFO_V1(dblink_current_query);
Datum
dblink_current_query(PG_FUNCTION_ARGS)
{
/* This is now just an alias for the built-in function current_query() */
PG_RETURN_DATUM(current_query(fcinfo));
}
/*
* Retrieve async notifications for a connection.
*
* Returns a setof record of notifications, or an empty set if none received.
* Can optionally take a named connection as parameter, but uses the unnamed
* connection per default.
*
*/
#define DBLINK_NOTIFY_COLS 3
PG_FUNCTION_INFO_V1(dblink_get_notify);
Datum
dblink_get_notify(PG_FUNCTION_ARGS)
{
PGconn *conn;
PGnotify *notify;
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
dblink_init();
if (PG_NARGS() == 1)
conn = dblink_get_named_conn(text_to_cstring(PG_GETARG_TEXT_PP(0)));
else
conn = pconn->conn;
InitMaterializedSRF(fcinfo, 0);
PQconsumeInput(conn);
while ((notify = PQnotifies(conn)) != NULL)
{
Datum values[DBLINK_NOTIFY_COLS];
bool nulls[DBLINK_NOTIFY_COLS];
memset(values, 0, sizeof(values));
memset(nulls, 0, sizeof(nulls));
if (notify->relname != NULL)
values[0] = CStringGetTextDatum(notify->relname);
else
nulls[0] = true;
values[1] = Int32GetDatum(notify->be_pid);
if (notify->extra != NULL)
values[2] = CStringGetTextDatum(notify->extra);
else
nulls[2] = true;
tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
PQfreemem(notify);
PQconsumeInput(conn);
}
return (Datum) 0;
}
/*
* Validate the options given to a dblink foreign server or user mapping.
* Raise an error if any option is invalid.
*
* We just check the names of options here, so semantic errors in options,
* such as invalid numeric format, will be detected at the attempt to connect.
*/
PG_FUNCTION_INFO_V1(dblink_fdw_validator);
Datum
dblink_fdw_validator(PG_FUNCTION_ARGS)
{
List *options_list = untransformRelOptions(PG_GETARG_DATUM(0));
Oid context = PG_GETARG_OID(1);
ListCell *cell;
static const PQconninfoOption *options = NULL;
/*
* Get list of valid libpq options.
*
* To avoid unnecessary work, we get the list once and use it throughout
* the lifetime of this backend process. We don't need to care about
* memory context issues, because PQconndefaults allocates with malloc.
*/
if (!options)
{
options = PQconndefaults();
if (!options) /* assume reason for failure is OOM */
ereport(ERROR,
(errcode(ERRCODE_FDW_OUT_OF_MEMORY),
errmsg("out of memory"),
errdetail("Could not get libpq's default connection options.")));
}
/* Validate each supplied option. */
foreach(cell, options_list)
{
DefElem *def = (DefElem *) lfirst(cell);
if (!is_valid_dblink_option(options, def->defname, context))
{
/*
* Unknown option, or invalid option for the context specified, so
* complain about it. Provide a hint with a valid option that
* looks similar, if there is one.
*/
const PQconninfoOption *opt;
const char *closest_match;
ClosestMatchState match_state;
bool has_valid_options = false;
initClosestMatch(&match_state, def->defname, 4);
for (opt = options; opt->keyword; opt++)
{
if (is_valid_dblink_option(options, opt->keyword, context))
{
has_valid_options = true;
updateClosestMatch(&match_state, opt->keyword);
}
}
closest_match = getClosestMatch(&match_state);
ereport(ERROR,
(errcode(ERRCODE_FDW_OPTION_NAME_NOT_FOUND),
errmsg("invalid option \"%s\"", def->defname),
has_valid_options ? closest_match ?
errhint("Perhaps you meant the option \"%s\".",
closest_match) : 0 :
errhint("There are no valid options in this context.")));
}
}
PG_RETURN_VOID();
}
/*************************************************************
* internal functions
*/
/*
* get_pkey_attnames
*
* Get the primary key attnames for the given relation.
* Return NULL, and set indnkeyatts = 0, if no primary key exists.
*/
static char **
get_pkey_attnames(Relation rel, int16 *indnkeyatts)
{
Relation indexRelation;
ScanKeyData skey;
SysScanDesc scan;
HeapTuple indexTuple;
int i;
char **result = NULL;
TupleDesc tupdesc;
/* initialize indnkeyatts to 0 in case no primary key exists */
*indnkeyatts = 0;
tupdesc = rel->rd_att;
/* Prepare to scan pg_index for entries having indrelid = this rel. */
indexRelation = table_open(IndexRelationId, AccessShareLock);
ScanKeyInit(&skey,
Anum_pg_index_indrelid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(RelationGetRelid(rel)));
scan = systable_beginscan(indexRelation, IndexIndrelidIndexId, true,
NULL, 1, &skey);
while (HeapTupleIsValid(indexTuple = systable_getnext(scan)))
{
Form_pg_index index = (Form_pg_index) GETSTRUCT(indexTuple);
/* we're only interested if it is the primary key */
if (index->indisprimary)
{
*indnkeyatts = index->indnkeyatts;
if (*indnkeyatts > 0)
{
result = palloc_array(char *, *indnkeyatts);
for (i = 0; i < *indnkeyatts; i++)
result[i] = SPI_fname(tupdesc, index->indkey.values[i]);
}
break;
}
}
systable_endscan(scan);
table_close(indexRelation, AccessShareLock);
return result;
}
/*
* Deconstruct a text[] into C-strings (note any NULL elements will be
* returned as NULL pointers)
*/
static char **
get_text_array_contents(ArrayType *array, int *numitems)
{
int ndim = ARR_NDIM(array);
int *dims = ARR_DIMS(array);
int nitems;
int16 typlen;
bool typbyval;
char typalign;
char **values;
char *ptr;
bits8 *bitmap;
int bitmask;
int i;
Assert(ARR_ELEMTYPE(array) == TEXTOID);
*numitems = nitems = ArrayGetNItems(ndim, dims);
get_typlenbyvalalign(ARR_ELEMTYPE(array),
&typlen, &typbyval, &typalign);
values = palloc_array(char *, nitems);
ptr = ARR_DATA_PTR(array);
bitmap = ARR_NULLBITMAP(array);
bitmask = 1;
for (i = 0; i < nitems; i++)
{
if (bitmap && (*bitmap & bitmask) == 0)
{
values[i] = NULL;
}
else
{
values[i] = TextDatumGetCString(PointerGetDatum(ptr));
ptr = att_addlength_pointer(ptr, typlen, ptr);
ptr = (char *) att_align_nominal(ptr, typalign);
}
/* advance bitmap pointer if any */
if (bitmap)
{
bitmask <<= 1;
if (bitmask == 0x100)
{
bitmap++;
bitmask = 1;
}
}
}
return values;
}
static char *
get_sql_insert(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals, char **tgt_pkattvals)
{
char *relname;
HeapTuple tuple;
TupleDesc tupdesc;
int natts;
StringInfoData buf;
char *val;
int key;
int i;
bool needComma;
initStringInfo(&buf);
/* get relation name including any needed schema prefix and quoting */
relname = generate_relation_name(rel);
tupdesc = rel->rd_att;
natts = tupdesc->natts;
tuple = get_tuple_of_interest(rel, pkattnums, pknumatts, src_pkattvals);
if (!tuple)
ereport(ERROR,
(errcode(ERRCODE_CARDINALITY_VIOLATION),
errmsg("source row not found")));
appendStringInfo(&buf, "INSERT INTO %s(", relname);
needComma = false;
for (i = 0; i < natts; i++)
{
Form_pg_attribute att = TupleDescAttr(tupdesc, i);
if (att->attisdropped)
continue;
if (needComma)
appendStringInfoChar(&buf, ',');
appendStringInfoString(&buf,
quote_ident_cstr(NameStr(att->attname)));
needComma = true;
}
appendStringInfoString(&buf, ") VALUES(");
/*
* Note: i is physical column number (counting from 0).
*/
needComma = false;
for (i = 0; i < natts; i++)
{
if (TupleDescAttr(tupdesc, i)->attisdropped)
continue;
if (needComma)
appendStringInfoChar(&buf, ',');
key = get_attnum_pk_pos(pkattnums, pknumatts, i);
if (key >= 0)
val = tgt_pkattvals[key] ? pstrdup(tgt_pkattvals[key]) : NULL;
else
val = SPI_getvalue(tuple, tupdesc, i + 1);
if (val != NULL)
{
appendStringInfoString(&buf, quote_literal_cstr(val));
pfree(val);
}
else
appendStringInfoString(&buf, "NULL");
needComma = true;
}
appendStringInfoChar(&buf, ')');
return buf.data;
}
static char *
get_sql_delete(Relation rel, int *pkattnums, int pknumatts, char **tgt_pkattvals)
{
char *relname;
TupleDesc tupdesc;
StringInfoData buf;
int i;
initStringInfo(&buf);
/* get relation name including any needed schema prefix and quoting */
relname = generate_relation_name(rel);
tupdesc = rel->rd_att;
appendStringInfo(&buf, "DELETE FROM %s WHERE ", relname);
for (i = 0; i < pknumatts; i++)
{
int pkattnum = pkattnums[i];
Form_pg_attribute attr = TupleDescAttr(tupdesc, pkattnum);
if (i > 0)
appendStringInfoString(&buf, " AND ");
appendStringInfoString(&buf,
quote_ident_cstr(NameStr(attr->attname)));
if (tgt_pkattvals[i] != NULL)
appendStringInfo(&buf, " = %s",
quote_literal_cstr(tgt_pkattvals[i]));
else
appendStringInfoString(&buf, " IS NULL");
}
return buf.data;
}
static char *
get_sql_update(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals, char **tgt_pkattvals)
{
char *relname;
HeapTuple tuple;
TupleDesc tupdesc;
int natts;
StringInfoData buf;
char *val;
int key;
int i;
bool needComma;
initStringInfo(&buf);
/* get relation name including any needed schema prefix and quoting */
relname = generate_relation_name(rel);
tupdesc = rel->rd_att;
natts = tupdesc->natts;
tuple = get_tuple_of_interest(rel, pkattnums, pknumatts, src_pkattvals);
if (!tuple)
ereport(ERROR,
(errcode(ERRCODE_CARDINALITY_VIOLATION),
errmsg("source row not found")));
appendStringInfo(&buf, "UPDATE %s SET ", relname);
/*
* Note: i is physical column number (counting from 0).
*/
needComma = false;
for (i = 0; i < natts; i++)
{
Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
if (attr->attisdropped)
continue;
if (needComma)
appendStringInfoString(&buf, ", ");
appendStringInfo(&buf, "%s = ",
quote_ident_cstr(NameStr(attr->attname)));
key = get_attnum_pk_pos(pkattnums, pknumatts, i);
if (key >= 0)
val = tgt_pkattvals[key] ? pstrdup(tgt_pkattvals[key]) : NULL;
else
val = SPI_getvalue(tuple, tupdesc, i + 1);
if (val != NULL)
{
appendStringInfoString(&buf, quote_literal_cstr(val));
pfree(val);
}
else
appendStringInfoString(&buf, "NULL");
needComma = true;
}
appendStringInfoString(&buf, " WHERE ");
for (i = 0; i < pknumatts; i++)
{
int pkattnum = pkattnums[i];
Form_pg_attribute attr = TupleDescAttr(tupdesc, pkattnum);
if (i > 0)
appendStringInfoString(&buf, " AND ");
appendStringInfoString(&buf,
quote_ident_cstr(NameStr(attr->attname)));
val = tgt_pkattvals[i];
if (val != NULL)
appendStringInfo(&buf, " = %s", quote_literal_cstr(val));
else
appendStringInfoString(&buf, " IS NULL");
}
return buf.data;
}
/*
* Return a properly quoted identifier.
* Uses quote_ident in quote.c
*/
static char *
quote_ident_cstr(char *rawstr)
{
text *rawstr_text;
text *result_text;
char *result;
rawstr_text = cstring_to_text(rawstr);
result_text = DatumGetTextPP(DirectFunctionCall1(quote_ident,
PointerGetDatum(rawstr_text)));
result = text_to_cstring(result_text);
return result;
}
static int
get_attnum_pk_pos(int *pkattnums, int pknumatts, int key)
{
int i;
/*
* Not likely a long list anyway, so just scan for the value
*/
for (i = 0; i < pknumatts; i++)
if (key == pkattnums[i])
return i;
return -1;
}
static HeapTuple
get_tuple_of_interest(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals)
{
char *relname;
TupleDesc tupdesc;
int natts;
StringInfoData buf;
int ret;
HeapTuple tuple;
int i;
/*
* Connect to SPI manager
*/
if ((ret = SPI_connect()) < 0)
/* internal error */
elog(ERROR, "SPI connect failure - returned %d", ret);
initStringInfo(&buf);
/* get relation name including any needed schema prefix and quoting */
relname = generate_relation_name(rel);
tupdesc = rel->rd_att;
natts = tupdesc->natts;
/*
* Build sql statement to look up tuple of interest, ie, the one matching
* src_pkattvals. We used to use "SELECT *" here, but it's simpler to
* generate a result tuple that matches the table's physical structure,
* with NULLs for any dropped columns. Otherwise we have to deal with two
* different tupdescs and everything's very confusing.
*/
appendStringInfoString(&buf, "SELECT ");
for (i = 0; i < natts; i++)
{
Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
if (i > 0)
appendStringInfoString(&buf, ", ");
if (attr->attisdropped)
appendStringInfoString(&buf, "NULL");
else
appendStringInfoString(&buf,
quote_ident_cstr(NameStr(attr->attname)));
}
appendStringInfo(&buf, " FROM %s WHERE ", relname);
for (i = 0; i < pknumatts; i++)
{
int pkattnum = pkattnums[i];
Form_pg_attribute attr = TupleDescAttr(tupdesc, pkattnum);
if (i > 0)
appendStringInfoString(&buf, " AND ");
appendStringInfoString(&buf,
quote_ident_cstr(NameStr(attr->attname)));
if (src_pkattvals[i] != NULL)
appendStringInfo(&buf, " = %s",
quote_literal_cstr(src_pkattvals[i]));
else
appendStringInfoString(&buf, " IS NULL");
}
/*
* Retrieve the desired tuple
*/
ret = SPI_exec(buf.data, 0);
pfree(buf.data);
/*
* Only allow one qualifying tuple
*/
if ((ret == SPI_OK_SELECT) && (SPI_processed > 1))
ereport(ERROR,
(errcode(ERRCODE_CARDINALITY_VIOLATION),
errmsg("source criteria matched more than one record")));
else if (ret == SPI_OK_SELECT && SPI_processed == 1)
{
SPITupleTable *tuptable = SPI_tuptable;
tuple = SPI_copytuple(tuptable->vals[0]);
SPI_finish();
return tuple;
}
else
{
/*
* no qualifying tuples
*/
SPI_finish();
return NULL;
}
/*
* never reached, but keep compiler quiet
*/
return NULL;
}
/*
* Open the relation named by relname_text, acquire specified type of lock,
* verify we have specified permissions.
* Caller must close rel when done with it.
*/
static Relation
get_rel_from_relname(text *relname_text, LOCKMODE lockmode, AclMode aclmode)
{
RangeVar *relvar;
Relation rel;
AclResult aclresult;
relvar = makeRangeVarFromNameList(textToQualifiedNameList(relname_text));
rel = table_openrv(relvar, lockmode);
aclresult = pg_class_aclcheck(RelationGetRelid(rel), GetUserId(),
aclmode);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, get_relkind_objtype(rel->rd_rel->relkind),
RelationGetRelationName(rel));
return rel;
}
/*
* generate_relation_name - copied from ruleutils.c
* Compute the name to display for a relation
*
* The result includes all necessary quoting and schema-prefixing.
*/
static char *
generate_relation_name(Relation rel)
{
char *nspname;
char *result;
/* Qualify the name if not visible in search path */
if (RelationIsVisible(RelationGetRelid(rel)))
nspname = NULL;
else
nspname = get_namespace_name(rel->rd_rel->relnamespace);
result = quote_qualified_identifier(nspname, RelationGetRelationName(rel));
return result;
}
static remoteConn *
getConnectionByName(const char *name)
{
remoteConnHashEnt *hentry;
char *key;
if (!remoteConnHash)
remoteConnHash = createConnHash();
key = pstrdup(name);
truncate_identifier(key, strlen(key), false);
hentry = (remoteConnHashEnt *) hash_search(remoteConnHash,
key, HASH_FIND, NULL);
if (hentry)
return hentry->rconn;
return NULL;
}
static HTAB *
createConnHash(void)
{
HASHCTL ctl;
ctl.keysize = NAMEDATALEN;
ctl.entrysize = sizeof(remoteConnHashEnt);
return hash_create("Remote Con hash", NUMCONN, &ctl,
HASH_ELEM | HASH_STRINGS);
}
static void
createNewConnection(const char *name, remoteConn *rconn)
{
remoteConnHashEnt *hentry;
bool found;
char *key;
if (!remoteConnHash)
remoteConnHash = createConnHash();
key = pstrdup(name);
truncate_identifier(key, strlen(key), true);
hentry = (remoteConnHashEnt *) hash_search(remoteConnHash, key,
HASH_ENTER, &found);
if (found)
{
libpqsrv_disconnect(rconn->conn);
pfree(rconn);
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("duplicate connection name")));
}
hentry->rconn = rconn;
}
static void
deleteConnection(const char *name)
{
remoteConnHashEnt *hentry;
bool found;
char *key;
if (!remoteConnHash)
remoteConnHash = createConnHash();
key = pstrdup(name);
truncate_identifier(key, strlen(key), false);
hentry = (remoteConnHashEnt *) hash_search(remoteConnHash,
key, HASH_REMOVE, &found);
if (!hentry)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("undefined connection name")));
}
/*
* We need to make sure that the connection made used credentials
* which were provided by the user, so check what credentials were
* used to connect and then make sure that they came from the user.
*/
static void
dblink_security_check(PGconn *conn, remoteConn *rconn, const char *connstr)
{
/* Superuser bypasses security check */
if (superuser())
return;
/* If password was used to connect, make sure it was one provided */
if (PQconnectionUsedPassword(conn) && dblink_connstr_has_pw(connstr))
return;
#ifdef ENABLE_GSS
/* If GSSAPI creds used to connect, make sure it was one delegated */
if (PQconnectionUsedGSSAPI(conn) && be_gssapi_get_delegation(MyProcPort))
return;
#endif
/* Otherwise, fail out */
libpqsrv_disconnect(conn);
if (rconn)
pfree(rconn);
ereport(ERROR,
(errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
errmsg("password or GSSAPI delegated credentials required"),
errdetail("Non-superusers may only connect using credentials they provide, eg: password in connection string or delegated GSSAPI credentials"),
errhint("Ensure provided credentials match target server's authentication method.")));
}
/*
* Function to check if the connection string includes an explicit
* password, needed to ensure that non-superuser password-based auth
* is using a provided password and not one picked up from the
* environment.
*/
static bool
dblink_connstr_has_pw(const char *connstr)
{
PQconninfoOption *options;
PQconninfoOption *option;
bool connstr_gives_password = false;
options = PQconninfoParse(connstr, NULL);
if (options)
{
for (option = options; option->keyword != NULL; option++)
{
if (strcmp(option->keyword, "password") == 0)
{
if (option->val != NULL && option->val[0] != '\0')
{
connstr_gives_password = true;
break;
}
}
}
PQconninfoFree(options);
}
return connstr_gives_password;
}
/*
* For non-superusers, insist that the connstr specify a password, except
* if GSSAPI credentials have been delegated (and we check that they are used
* for the connection in dblink_security_check later). This prevents a
* password or GSSAPI credentials from being picked up from .pgpass, a
* service file, the environment, etc. We don't want the postgres user's
* passwords or Kerberos credentials to be accessible to non-superusers.
*/
static void
dblink_connstr_check(const char *connstr)
{
if (superuser())
return;
if (dblink_connstr_has_pw(connstr))
return;
#ifdef ENABLE_GSS
if (be_gssapi_get_delegation(MyProcPort))
return;
#endif
ereport(ERROR,
(errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
errmsg("password or GSSAPI delegated credentials required"),
errdetail("Non-superusers must provide a password in the connection string or send delegated GSSAPI credentials.")));
}
/*
* Report an error received from the remote server
*
* res: the received error result (will be freed)
* fail: true for ERROR ereport, false for NOTICE
* fmt and following args: sprintf-style format and values for errcontext;
* the resulting string should be worded like "while <some action>"
*/
static void
dblink_res_error(PGconn *conn, const char *conname, PGresult *res,
bool fail, const char *fmt,...)
{
int level;
char *pg_diag_sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
char *pg_diag_message_primary = PQresultErrorField(res, PG_DIAG_MESSAGE_PRIMARY);
char *pg_diag_message_detail = PQresultErrorField(res, PG_DIAG_MESSAGE_DETAIL);
char *pg_diag_message_hint = PQresultErrorField(res, PG_DIAG_MESSAGE_HINT);
char *pg_diag_context = PQresultErrorField(res, PG_DIAG_CONTEXT);
int sqlstate;
char *message_primary;
char *message_detail;
char *message_hint;
char *message_context;
va_list ap;
char dblink_context_msg[512];
if (fail)
level = ERROR;
else
level = NOTICE;
if (pg_diag_sqlstate)
sqlstate = MAKE_SQLSTATE(pg_diag_sqlstate[0],
pg_diag_sqlstate[1],
pg_diag_sqlstate[2],
pg_diag_sqlstate[3],
pg_diag_sqlstate[4]);
else
sqlstate = ERRCODE_CONNECTION_FAILURE;
message_primary = xpstrdup(pg_diag_message_primary);
message_detail = xpstrdup(pg_diag_message_detail);
message_hint = xpstrdup(pg_diag_message_hint);
message_context = xpstrdup(pg_diag_context);
/*
* If we don't get a message from the PGresult, try the PGconn. This is
* needed because for connection-level failures, PQgetResult may just
* return NULL, not a PGresult at all.
*/
if (message_primary == NULL)
message_primary = pchomp(PQerrorMessage(conn));
/*
* Now that we've copied all the data we need out of the PGresult, it's
* safe to free it. We must do this to avoid PGresult leakage. We're
* leaking all the strings too, but those are in palloc'd memory that will
* get cleaned up eventually.
*/
PQclear(res);
/*
* Format the basic errcontext string. Below, we'll add on something
* about the connection name. That's a violation of the translatability
* guidelines about constructing error messages out of parts, but since
* there's no translation support for dblink, there's no need to worry
* about that (yet).
*/
va_start(ap, fmt);
vsnprintf(dblink_context_msg, sizeof(dblink_context_msg), fmt, ap);
va_end(ap);
ereport(level,
(errcode(sqlstate),
(message_primary != NULL && message_primary[0] != '\0') ?
errmsg_internal("%s", message_primary) :
errmsg("could not obtain message string for remote error"),
message_detail ? errdetail_internal("%s", message_detail) : 0,
message_hint ? errhint("%s", message_hint) : 0,
message_context ? (errcontext("%s", message_context)) : 0,
conname ?
(errcontext("%s on dblink connection named \"%s\"",
dblink_context_msg, conname)) :
(errcontext("%s on unnamed dblink connection",
dblink_context_msg))));
}
/*
* Obtain connection string for a foreign server
*/
static char *
get_connect_string(const char *servername)
{
ForeignServer *foreign_server = NULL;
UserMapping *user_mapping;
ListCell *cell;
StringInfoData buf;
ForeignDataWrapper *fdw;
AclResult aclresult;
char *srvname;
static const PQconninfoOption *options = NULL;
initStringInfo(&buf);
/*
* Get list of valid libpq options.
*
* To avoid unnecessary work, we get the list once and use it throughout
* the lifetime of this backend process. We don't need to care about
* memory context issues, because PQconndefaults allocates with malloc.
*/
if (!options)
{
options = PQconndefaults();
if (!options) /* assume reason for failure is OOM */
ereport(ERROR,
(errcode(ERRCODE_FDW_OUT_OF_MEMORY),
errmsg("out of memory"),
errdetail("Could not get libpq's default connection options.")));
}
/* first gather the server connstr options */
srvname = pstrdup(servername);
truncate_identifier(srvname, strlen(srvname), false);
foreign_server = GetForeignServerByName(srvname, true);
if (foreign_server)
{
Oid serverid = foreign_server->serverid;
Oid fdwid = foreign_server->fdwid;
Oid userid = GetUserId();
user_mapping = GetUserMapping(userid, serverid);
fdw = GetForeignDataWrapper(fdwid);
/* Check permissions, user must have usage on the server. */
aclresult = object_aclcheck(ForeignServerRelationId, serverid, userid, ACL_USAGE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_FOREIGN_SERVER, foreign_server->servername);
foreach(cell, fdw->options)
{
DefElem *def = lfirst(cell);
if (is_valid_dblink_option(options, def->defname, ForeignDataWrapperRelationId))
appendStringInfo(&buf, "%s='%s' ", def->defname,
escape_param_str(strVal(def->arg)));
}
foreach(cell, foreign_server->options)
{
DefElem *def = lfirst(cell);
if (is_valid_dblink_option(options, def->defname, ForeignServerRelationId))
appendStringInfo(&buf, "%s='%s' ", def->defname,
escape_param_str(strVal(def->arg)));
}
foreach(cell, user_mapping->options)
{
DefElem *def = lfirst(cell);
if (is_valid_dblink_option(options, def->defname, UserMappingRelationId))
appendStringInfo(&buf, "%s='%s' ", def->defname,
escape_param_str(strVal(def->arg)));
}
return buf.data;
}
else
return NULL;
}
/*
* Escaping libpq connect parameter strings.
*
* Replaces "'" with "\'" and "\" with "\\".
*/
static char *
escape_param_str(const char *str)
{
const char *cp;
StringInfoData buf;
initStringInfo(&buf);
for (cp = str; *cp; cp++)
{
if (*cp == '\\' || *cp == '\'')
appendStringInfoChar(&buf, '\\');
appendStringInfoChar(&buf, *cp);
}
return buf.data;
}
/*
* Validate the PK-attnums argument for dblink_build_sql_insert() and related
* functions, and translate to the internal representation.
*
* The user supplies an int2vector of 1-based logical attnums, plus a count
* argument (the need for the separate count argument is historical, but we
* still check it). We check that each attnum corresponds to a valid,
* non-dropped attribute of the rel. We do *not* prevent attnums from being
* listed twice, though the actual use-case for such things is dubious.
* Note that before Postgres 9.0, the user's attnums were interpreted as
* physical not logical column numbers; this was changed for future-proofing.
*
* The internal representation is a palloc'd int array of 0-based physical
* attnums.
*/
static void
validate_pkattnums(Relation rel,
int2vector *pkattnums_arg, int32 pknumatts_arg,
int **pkattnums, int *pknumatts)
{
TupleDesc tupdesc = rel->rd_att;
int natts = tupdesc->natts;
int i;
/* Don't take more array elements than there are */
pknumatts_arg = Min(pknumatts_arg, pkattnums_arg->dim1);
/* Must have at least one pk attnum selected */
if (pknumatts_arg <= 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("number of key attributes must be > 0")));
/* Allocate output array */
*pkattnums = palloc_array(int, pknumatts_arg);
*pknumatts = pknumatts_arg;
/* Validate attnums and convert to internal form */
for (i = 0; i < pknumatts_arg; i++)
{
int pkattnum = pkattnums_arg->values[i];
int lnum;
int j;
/* Can throw error immediately if out of range */
if (pkattnum <= 0 || pkattnum > natts)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid attribute number %d", pkattnum)));
/* Identify which physical column has this logical number */
lnum = 0;
for (j = 0; j < natts; j++)
{
/* dropped columns don't count */
if (TupleDescAttr(tupdesc, j)->attisdropped)
continue;
if (++lnum == pkattnum)
break;
}
if (j < natts)
(*pkattnums)[i] = j;
else
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid attribute number %d", pkattnum)));
}
}
/*
* Check if the specified connection option is valid.
*
* We basically allow whatever libpq thinks is an option, with these
* restrictions:
* debug options: disallowed
* "client_encoding": disallowed
* "user": valid only in USER MAPPING options
* secure options (eg password): valid only in USER MAPPING options
* others: valid only in FOREIGN SERVER options
*
* We disallow client_encoding because it would be overridden anyway via
* PQclientEncoding; allowing it to be specified would merely promote
* confusion.
*/
static bool
is_valid_dblink_option(const PQconninfoOption *options, const char *option,
Oid context)
{
const PQconninfoOption *opt;
/* Look up the option in libpq result */
for (opt = options; opt->keyword; opt++)
{
if (strcmp(opt->keyword, option) == 0)
break;
}
if (opt->keyword == NULL)
return false;
/* Disallow debug options (particularly "replication") */
if (strchr(opt->dispchar, 'D'))
return false;
/* Disallow "client_encoding" */
if (strcmp(opt->keyword, "client_encoding") == 0)
return false;
/*
* If the option is "user" or marked secure, it should be specified only
* in USER MAPPING. Others should be specified only in SERVER.
*/
if (strcmp(opt->keyword, "user") == 0 || strchr(opt->dispchar, '*'))
{
if (context != UserMappingRelationId)
return false;
}
else
{
if (context != ForeignServerRelationId)
return false;
}
return true;
}
/*
* Copy the remote session's values of GUCs that affect datatype I/O
* and apply them locally in a new GUC nesting level. Returns the new
* nestlevel (which is needed by restoreLocalGucs to undo the settings),
* or -1 if no new nestlevel was needed.
*
* We use the equivalent of a function SET option to allow the settings to
* persist only until the caller calls restoreLocalGucs. If an error is
* thrown in between, guc.c will take care of undoing the settings.
*/
static int
applyRemoteGucs(PGconn *conn)
{
static const char *const GUCsAffectingIO[] = {
"DateStyle",
"IntervalStyle"
};
int nestlevel = -1;
int i;
for (i = 0; i < lengthof(GUCsAffectingIO); i++)
{
const char *gucName = GUCsAffectingIO[i];
const char *remoteVal = PQparameterStatus(conn, gucName);
const char *localVal;
/*
* If the remote server is pre-8.4, it won't have IntervalStyle, but
* that's okay because its output format won't be ambiguous. So just
* skip the GUC if we don't get a value for it. (We might eventually
* need more complicated logic with remote-version checks here.)
*/
if (remoteVal == NULL)
continue;
/*
* Avoid GUC-setting overhead if the remote and local GUCs already
* have the same value.
*/
localVal = GetConfigOption(gucName, false, false);
Assert(localVal != NULL);
if (strcmp(remoteVal, localVal) == 0)
continue;
/* Create new GUC nest level if we didn't already */
if (nestlevel < 0)
nestlevel = NewGUCNestLevel();
/* Apply the option (this will throw error on failure) */
(void) set_config_option(gucName, remoteVal,
PGC_USERSET, PGC_S_SESSION,
GUC_ACTION_SAVE, true, 0, false);
}
return nestlevel;
}
/*
* Restore local GUCs after they have been overlaid with remote settings.
*/
static void
restoreLocalGucs(int nestlevel)
{
/* Do nothing if no new nestlevel was created */
if (nestlevel > 0)
AtEOXact_GUC(true, nestlevel);
}
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