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postgresql/contrib/dblink/dblink.c
Robert Haas 568d4138c6 Use an MVCC snapshot, rather than SnapshotNow, for catalog scans. 
SnapshotNow scans have the undesirable property that, in the face of
concurrent updates, the scan can fail to see either the old or the new
versions of the row.  In many cases, we work around this by requiring
DDL operations to hold AccessExclusiveLock on the object being
modified; in some cases, the existing locking is inadequate and random
failures occur as a result.  This commit doesn't change anything
related to locking, but will hopefully pave the way to allowing lock
strength reductions in the future.

The major issue has held us back from making this change in the past
is that taking an MVCC snapshot is significantly more expensive than
using a static special snapshot such as SnapshotNow.  However, testing
of various worst-case scenarios reveals that this problem is not
severe except under fairly extreme workloads.  To mitigate those
problems, we avoid retaking the MVCC snapshot for each new scan;
instead, we take a new snapshot only when invalidation messages have
been processed.  The catcache machinery already requires that
invalidation messages be sent before releasing the related heavyweight
lock; else other backends might rely on locally-cached data rather
than scanning the catalog at all.  Thus, making snapshot reuse
dependent on the same guarantees shouldn't break anything that wasn't
already subtly broken.

Patch by me.  Review by Michael Paquier and Andres Freund.
2013-07-02 09:47:01 -04:00

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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) 2001-2013, 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 "libpq-fe.h"
#include "access/htup_details.h"
#include "access/reloptions.h"
#include "catalog/indexing.h"
#include "catalog/namespace.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 "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/tqual.h"
#include "dblink.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(storeInfo *sinfo, PGconn *conn, const char *sql);
static void storeRow(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 *numatts);
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 void dblink_security_check(PGconn *conn, remoteConn *rconn);
static void dblink_res_error(const char *conname, PGresult *res, const char *dblink_context_msg, bool fail);
static char *get_connect_string(const char *servername);
static char *escape_param_str(const char *from);
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;
/*
* 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
/* general utility */
#define xpfree(var_) \
do { \
if (var_ != NULL) \
{ \
pfree(var_); \
var_ = NULL; \
} \
} while (0)
#define xpstrdup(var_c, var_) \
do { \
if (var_ != NULL) \
var_c = pstrdup(var_); \
else \
var_c = NULL; \
} while (0)
#define DBLINK_RES_INTERNALERROR(p2) \
do { \
msg = pstrdup(PQerrorMessage(conn)); \
if (res) \
PQclear(res); \
elog(ERROR, "%s: %s", p2, msg); \
} while (0)
#define DBLINK_CONN_NOT_AVAIL \
do { \
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"))); \
} while (0)
#define DBLINK_GET_CONN \
do { \
char *conname_or_str = text_to_cstring(PG_GETARG_TEXT_PP(0)); \
rconn = getConnectionByName(conname_or_str); \
if (rconn) \
{ \
conn = rconn->conn; \
conname = conname_or_str; \
} \
else \
{ \
connstr = get_connect_string(conname_or_str); \
if (connstr == NULL) \
{ \
connstr = conname_or_str; \
} \
dblink_connstr_check(connstr); \
conn = PQconnectdb(connstr); \
if (PQstatus(conn) == CONNECTION_BAD) \
{ \
msg = pstrdup(PQerrorMessage(conn)); \
PQfinish(conn); \
ereport(ERROR, \
(errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION), \
errmsg("could not establish connection"), \
errdetail_internal("%s", msg))); \
} \
dblink_security_check(conn, rconn); \
PQsetClientEncoding(conn, GetDatabaseEncodingName()); \
freeconn = true; \
} \
} while (0)
#define DBLINK_GET_NAMED_CONN \
do { \
conname = text_to_cstring(PG_GETARG_TEXT_PP(0)); \
rconn = getConnectionByName(conname); \
if (rconn) \
conn = rconn->conn; \
else \
DBLINK_CONN_NOT_AVAIL; \
} while (0)
#define DBLINK_INIT \
do { \
if (!pconn) \
{ \
pconn = (remoteConn *) MemoryContextAlloc(TopMemoryContext, sizeof(remoteConn)); \
pconn->conn = NULL; \
pconn->openCursorCount = 0; \
pconn->newXactForCursor = FALSE; \
} \
} while (0)
/*
* 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));
/* 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);
conn = PQconnectdb(connstr);
if (PQstatus(conn) == CONNECTION_BAD)
{
msg = pstrdup(PQerrorMessage(conn));
PQfinish(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);
/* attempt to set client encoding to match server encoding */
PQsetClientEncoding(conn, GetDatabaseEncodingName());
if (connname)
{
rconn->conn = conn;
createNewConnection(connname, rconn);
}
else
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;
PQfinish(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)
{
char *msg;
PGresult *res = NULL;
PGconn *conn = NULL;
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;
else
conn = rconn->conn;
/* If we are not in a transaction, start one */
if (PQtransactionStatus(conn) == PQTRANS_IDLE)
{
res = PQexec(conn, "BEGIN");
if (PQresultStatus(res) != PGRES_COMMAND_OK)
DBLINK_RES_INTERNALERROR("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 = PQexec(conn, buf.data);
if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
{
dblink_res_error(conname, res, "could not open cursor", fail);
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 = NULL;
PGresult *res = NULL;
char *curname = NULL;
char *conname = NULL;
StringInfoData buf;
char *msg;
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;
else
conn = rconn->conn;
appendStringInfo(&buf, "CLOSE %s", curname);
/* close the cursor */
res = PQexec(conn, buf.data);
if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
{
dblink_res_error(conname, res, "could not close cursor", fail);
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 = PQexec(conn, "COMMIT");
if (PQresultStatus(res) != PGRES_COMMAND_OK)
DBLINK_RES_INTERNALERROR("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;
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 = PQexec(conn, buf.data);
if (!res ||
(PQresultStatus(res) != PGRES_COMMAND_OK &&
PQresultStatus(res) != PGRES_TUPLES_OK))
{
dblink_res_error(conname, res, "could not fetch from cursor", fail);
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)
{
char *conname = NULL;
PGconn *conn = NULL;
char *sql = NULL;
remoteConn *rconn = NULL;
int retval;
if (PG_NARGS() == 2)
{
DBLINK_GET_NAMED_CONN;
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", 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 *msg;
char *connstr = NULL;
char *sql = NULL;
char *conname = NULL;
remoteConn *rconn = NULL;
bool fail = true; /* default to backward compatible */
if (!is_async)
{
if (PG_NARGS() == 3)
{
/* text,text,bool */
DBLINK_GET_CONN;
sql = text_to_cstring(PG_GETARG_TEXT_PP(1));
fail = PG_GETARG_BOOL(2);
}
else if (PG_NARGS() == 2)
{
/* text,text or text,bool */
if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
{
conn = pconn->conn;
sql = text_to_cstring(PG_GETARG_TEXT_PP(0));
fail = PG_GETARG_BOOL(1);
}
else
{
DBLINK_GET_CONN;
sql = text_to_cstring(PG_GETARG_TEXT_PP(1));
}
}
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 */
if (PG_NARGS() == 2)
{
/* text,bool */
DBLINK_GET_NAMED_CONN;
fail = PG_GETARG_BOOL(1);
}
else if (PG_NARGS() == 1)
{
/* text */
DBLINK_GET_NAMED_CONN;
}
else
/* shouldn't happen */
elog(ERROR, "wrong number of arguments");
}
if (!conn)
DBLINK_CONN_NOT_AVAIL;
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 = PQgetResult(conn);
/* 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(conname, res, "could not execute query",
fail);
/* if fail isn't set, we'll return an empty query result */
}
else
{
materializeResult(fcinfo, conn, res);
}
}
}
}
PG_CATCH();
{
/* if needed, close the connection to the database */
if (freeconn)
PQfinish(conn);
PG_RE_THROW();
}
PG_END_TRY();
/* if needed, close the connection to the database */
if (freeconn)
PQfinish(conn);
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, false);
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 = (char **) palloc(nfields * sizeof(char *));
/* 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);
/* clean up and return the tuplestore */
tuplestore_donestoring(tupstore);
}
PQclear(res);
}
PG_CATCH();
{
/* be sure to release the libpq result */
PQclear(res);
PG_RE_THROW();
}
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;
storeInfo sinfo;
/* prepTuplestoreResult must have been called previously */
Assert(rsinfo->returnMode == SFRM_Materialize);
/* initialize storeInfo to empty */
memset(&sinfo, 0, sizeof(sinfo));
sinfo.fcinfo = fcinfo;
PG_TRY();
{
/* 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(conname, res1, "could not execute query", fail);
/* 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, false);
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;
}
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 = PQgetResult(conn)) != NULL)
PQclear(res);
PG_RE_THROW();
}
PG_END_TRY();
}
/*
* Execute query, and send any result rows to sinfo->tuplestore.
*/
static PGresult *
storeQueryResult(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", 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 = PQgetResult(conn);
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(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 = (char **) palloc(nfields * sizeof(char *));
/* Create short-lived memory context for data conversions */
if (!sinfo->tmpcontext)
sinfo->tmpcontext =
AllocSetContextCreate(CurrentMemoryContext,
"dblink temporary context",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
}
/* 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_ARRAYTYPE_P(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)
{
char *conname = NULL;
PGconn *conn = NULL;
remoteConn *rconn = NULL;
DBLINK_INIT;
DBLINK_GET_NAMED_CONN;
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)
{
int res = 0;
char *conname = NULL;
PGconn *conn = NULL;
remoteConn *rconn = NULL;
PGcancel *cancel;
char errbuf[256];
DBLINK_INIT;
DBLINK_GET_NAMED_CONN;
cancel = PQgetCancel(conn);
res = PQcancel(cancel, errbuf, 256);
PQfreeCancel(cancel);
if (res == 1)
PG_RETURN_TEXT_P(cstring_to_text("OK"));
else
PG_RETURN_TEXT_P(cstring_to_text(errbuf));
}
/*
* 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;
char *conname = NULL;
PGconn *conn = NULL;
remoteConn *rconn = NULL;
DBLINK_INIT;
DBLINK_GET_NAMED_CONN;
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(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();
{
char *msg;
PGresult *res = NULL;
char *connstr = NULL;
char *sql = NULL;
char *conname = NULL;
remoteConn *rconn = NULL;
bool fail = true; /* default to backward compatible behavior */
if (PG_NARGS() == 3)
{
/* must be text,text,bool */
DBLINK_GET_CONN;
sql = text_to_cstring(PG_GETARG_TEXT_PP(1));
fail = PG_GETARG_BOOL(2);
}
else if (PG_NARGS() == 2)
{
/* might be text,text or text,bool */
if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
{
conn = pconn->conn;
sql = text_to_cstring(PG_GETARG_TEXT_PP(0));
fail = PG_GETARG_BOOL(1);
}
else
{
DBLINK_GET_CONN;
sql = text_to_cstring(PG_GETARG_TEXT_PP(1));
}
}
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;
res = PQexec(conn, sql);
if (!res ||
(PQresultStatus(res) != PGRES_COMMAND_OK &&
PQresultStatus(res) != PGRES_TUPLES_OK))
{
dblink_res_error(conname, res, "could not execute command", fail);
/*
* 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_CATCH();
{
/* if needed, close the connection to the database */
if (freeconn)
PQfinish(conn);
PG_RE_THROW();
}
PG_END_TRY();
/* if needed, close the connection to the database */
if (freeconn)
PQfinish(conn);
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 numatts;
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_P(0), AccessShareLock, ACL_SELECT);
/* get the array of attnums */
results = get_pkey_attnames(rel, &numatts);
relation_close(rel, AccessShareLock);
/*
* need a tuple descriptor representing one INT and one TEXT column
*/
tupdesc = CreateTemplateTupleDesc(2, false);
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) && (numatts > 0))
{
funcctx->max_calls = numatts;
/* 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 = (char **) palloc(2 * sizeof(char *));
values[0] = (char *) palloc(12); /* sign, 10 digits, '\0' */
sprintf(values[0], "%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_P(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_P(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_P(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)
{
char *conname = NULL;
PGconn *conn = NULL;
remoteConn *rconn = NULL;
PGnotify *notify;
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
TupleDesc tupdesc;
Tuplestorestate *tupstore;
MemoryContext per_query_ctx;
MemoryContext oldcontext;
prepTuplestoreResult(fcinfo);
DBLINK_INIT;
if (PG_NARGS() == 1)
DBLINK_GET_NAMED_CONN;
else
conn = pconn->conn;
/* create the tuplestore in per-query memory */
per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
oldcontext = MemoryContextSwitchTo(per_query_ctx);
tupdesc = CreateTemplateTupleDesc(DBLINK_NOTIFY_COLS, false);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "notify_name",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "be_pid",
INT4OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 3, "extra",
TEXTOID, -1, 0);
tupstore = tuplestore_begin_heap(true, false, work_mem);
rsinfo->setResult = tupstore;
rsinfo->setDesc = tupdesc;
MemoryContextSwitchTo(oldcontext);
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(tupstore, tupdesc, values, nulls);
PQfreemem(notify);
PQconsumeInput(conn);
}
/* clean up and return the tuplestore */
tuplestore_donestoring(tupstore);
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 list of valid options
* for the context.
*/
StringInfoData buf;
const PQconninfoOption *opt;
initStringInfo(&buf);
for (opt = options; opt->keyword; opt++)
{
if (is_valid_dblink_option(options, opt->keyword, context))
appendStringInfo(&buf, "%s%s",
(buf.len > 0) ? ", " : "",
opt->keyword);
}
ereport(ERROR,
(errcode(ERRCODE_FDW_OPTION_NAME_NOT_FOUND),
errmsg("invalid option \"%s\"", def->defname),
errhint("Valid options in this context are: %s",
buf.data)));
}
}
PG_RETURN_VOID();
}
/*************************************************************
* internal functions
*/
/*
* get_pkey_attnames
*
* Get the primary key attnames for the given relation.
* Return NULL, and set numatts = 0, if no primary key exists.
*/
static char **
get_pkey_attnames(Relation rel, int16 *numatts)
{
Relation indexRelation;
ScanKeyData skey;
SysScanDesc scan;
HeapTuple indexTuple;
int i;
char **result = NULL;
TupleDesc tupdesc;
/* initialize numatts to 0 in case no primary key exists */
*numatts = 0;
tupdesc = rel->rd_att;
/* Prepare to scan pg_index for entries having indrelid = this rel. */
indexRelation = heap_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)
{
*numatts = index->indnatts;
if (*numatts > 0)
{
result = (char **) palloc(*numatts * sizeof(char *));
for (i = 0; i < *numatts; i++)
result[i] = SPI_fname(tupdesc, index->indkey.values[i]);
}
break;
}
}
systable_endscan(scan);
heap_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 = (char **) palloc(nitems * sizeof(char *));
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++)
{
if (tupdesc->attrs[i]->attisdropped)
continue;
if (needComma)
appendStringInfo(&buf, ",");
appendStringInfoString(&buf,
quote_ident_cstr(NameStr(tupdesc->attrs[i]->attname)));
needComma = true;
}
appendStringInfo(&buf, ") VALUES(");
/*
* Note: i is physical column number (counting from 0).
*/
needComma = false;
for (i = 0; i < natts; i++)
{
if (tupdesc->attrs[i]->attisdropped)
continue;
if (needComma)
appendStringInfo(&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
appendStringInfo(&buf, "NULL");
needComma = true;
}
appendStringInfo(&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];
if (i > 0)
appendStringInfo(&buf, " AND ");
appendStringInfoString(&buf,
quote_ident_cstr(NameStr(tupdesc->attrs[pkattnum]->attname)));
if (tgt_pkattvals[i] != NULL)
appendStringInfo(&buf, " = %s",
quote_literal_cstr(tgt_pkattvals[i]));
else
appendStringInfo(&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++)
{
if (tupdesc->attrs[i]->attisdropped)
continue;
if (needComma)
appendStringInfo(&buf, ", ");
appendStringInfo(&buf, "%s = ",
quote_ident_cstr(NameStr(tupdesc->attrs[i]->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;
}
appendStringInfo(&buf, " WHERE ");
for (i = 0; i < pknumatts; i++)
{
int pkattnum = pkattnums[i];
if (i > 0)
appendStringInfo(&buf, " AND ");
appendStringInfo(&buf, "%s",
quote_ident_cstr(NameStr(tupdesc->attrs[pkattnum]->attname)));
val = tgt_pkattvals[i];
if (val != NULL)
appendStringInfo(&buf, " = %s", quote_literal_cstr(val));
else
appendStringInfo(&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 = DatumGetTextP(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++)
{
if (i > 0)
appendStringInfoString(&buf, ", ");
if (tupdesc->attrs[i]->attisdropped)
appendStringInfoString(&buf, "NULL");
else
appendStringInfoString(&buf,
quote_ident_cstr(NameStr(tupdesc->attrs[i]->attname)));
}
appendStringInfo(&buf, " FROM %s WHERE ", relname);
for (i = 0; i < pknumatts; i++)
{
int pkattnum = pkattnums[i];
if (i > 0)
appendStringInfo(&buf, " AND ");
appendStringInfoString(&buf,
quote_ident_cstr(NameStr(tupdesc->attrs[pkattnum]->attname)));
if (src_pkattvals[i] != NULL)
appendStringInfo(&buf, " = %s",
quote_literal_cstr(src_pkattvals[i]));
else
appendStringInfo(&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 = heap_openrv(relvar, lockmode);
aclresult = pg_class_aclcheck(RelationGetRelid(rel), GetUserId(),
aclmode);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, ACL_KIND_CLASS,
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);
}
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)
{
PQfinish(rconn->conn);
pfree(rconn);
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("duplicate connection name")));
}
hentry->rconn = rconn;
strlcpy(hentry->name, name, sizeof(hentry->name));
}
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")));
}
static void
dblink_security_check(PGconn *conn, remoteConn *rconn)
{
if (!superuser())
{
if (!PQconnectionUsedPassword(conn))
{
PQfinish(conn);
if (rconn)
pfree(rconn);
ereport(ERROR,
(errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
errmsg("password is required"),
errdetail("Non-superuser cannot connect if the server does not request a password."),
errhint("Target server's authentication method must be changed.")));
}
}
}
/*
* For non-superusers, insist that the connstr specify a password. This
* prevents a password from being picked up from .pgpass, a service file,
* the environment, etc. We don't want the postgres user's passwords
* to be accessible to non-superusers.
*/
static void
dblink_connstr_check(const char *connstr)
{
if (!superuser())
{
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);
}
if (!connstr_gives_password)
ereport(ERROR,
(errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
errmsg("password is required"),
errdetail("Non-superusers must provide a password in the connection string.")));
}
}
static void
dblink_res_error(const char *conname, PGresult *res, const char *dblink_context_msg, bool fail)
{
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;
const char *dblink_context_conname = "unnamed";
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;
xpstrdup(message_primary, pg_diag_message_primary);
xpstrdup(message_detail, pg_diag_message_detail);
xpstrdup(message_hint, pg_diag_message_hint);
xpstrdup(message_context, pg_diag_context);
if (res)
PQclear(res);
if (conname)
dblink_context_conname = conname;
ereport(level,
(errcode(sqlstate),
message_primary ? errmsg_internal("%s", message_primary) :
errmsg("unknown error"),
message_detail ? errdetail_internal("%s", message_detail) : 0,
message_hint ? errhint("%s", message_hint) : 0,
message_context ? errcontext("%s", message_context) : 0,
errcontext("Error occurred on dblink connection named \"%s\": %s.",
dblink_context_conname, 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;
StringInfo buf = makeStringInfo();
ForeignDataWrapper *fdw;
AclResult aclresult;
char *srvname;
/* 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 = pg_foreign_server_aclcheck(serverid, userid, ACL_USAGE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, ACL_KIND_FOREIGN_SERVER, foreign_server->servername);
foreach(cell, fdw->options)
{
DefElem *def = lfirst(cell);
appendStringInfo(buf, "%s='%s' ", def->defname,
escape_param_str(strVal(def->arg)));
}
foreach(cell, foreign_server->options)
{
DefElem *def = lfirst(cell);
appendStringInfo(buf, "%s='%s' ", def->defname,
escape_param_str(strVal(def->arg)));
}
foreach(cell, user_mapping->options)
{
DefElem *def = lfirst(cell);
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;
StringInfo buf = makeStringInfo();
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 = (int *) palloc(pknumatts_arg * sizeof(int));
*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 (tupdesc->attrs[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);
}
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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