Fix SetClientEncoding() to maintain a cache of previously selected encoding
conversion functions. This allows transaction rollback to revert to a previous client_encoding setting without doing fresh catalog lookups. I believe that this explains and fixes the recent report of "failed to commit client_encoding" failures. This bug is present in 8.3.x, but it doesn't seem prudent to back-patch the fix, at least not till it's had some time for field testing in HEAD. In passing, remove SetDefaultClientEncoding(), which was used nowhere.
This commit is contained in:
Tom Lane
parent
33e7eac37c
commit
c26ffb1ead
@ -1,10 +1,10 @@
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/*
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* This file contains public functions for conversion between
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* client encoding and server internal encoding.
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* (currently mule internal code (mic) is used)
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* client encoding and server (database) encoding.
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*
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* Tatsuo Ishii
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*
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* $PostgreSQL: pgsql/src/backend/utils/mb/mbutils.c,v 1.82 2009/03/09 00:01:32 alvherre Exp $
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* $PostgreSQL: pgsql/src/backend/utils/mb/mbutils.c,v 1.83 2009/04/02 17:30:53 tgl Exp $
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*/
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#include "postgres.h"
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@ -28,23 +28,37 @@
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#define MAX_CONVERSION_GROWTH 4
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/*
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* We handle for actual FE and BE encoding setting encoding-identificator
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* and encoding-name too. It prevent searching and conversion from encoding
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* to encoding name in getdatabaseencoding() and other routines.
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* We maintain a simple linked list caching the fmgr lookup info for the
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* currently selected conversion functions, as well as any that have been
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* selected previously in the current session. (We remember previous
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* settings because we must be able to restore a previous setting during
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* transaction rollback, without doing any fresh catalog accesses.)
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*
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* Since we'll never release this data, we just keep it in TopMemoryContext.
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*/
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typedef struct ConvProcInfo
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{
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int s_encoding; /* server and client encoding IDs */
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int c_encoding;
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FmgrInfo to_server_info; /* lookup info for conversion procs */
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FmgrInfo to_client_info;
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} ConvProcInfo;
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static List *ConvProcList = NIL; /* List of ConvProcInfo */
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/*
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* These variables point to the currently active conversion functions,
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* or are NULL when no conversion is needed.
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*/
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static FmgrInfo *ToServerConvProc = NULL;
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static FmgrInfo *ToClientConvProc = NULL;
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/*
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* These variables track the currently selected FE and BE encodings.
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*/
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static pg_enc2name *ClientEncoding = &pg_enc2name_tbl[PG_SQL_ASCII];
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static pg_enc2name *DatabaseEncoding = &pg_enc2name_tbl[PG_SQL_ASCII];
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/*
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* Caches for conversion function info. These values are allocated in
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* MbProcContext. That context is a child of TopMemoryContext,
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* which allows these values to survive across transactions. See
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* SetClientEncoding() for more details.
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*/
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static MemoryContext MbProcContext = NULL;
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static FmgrInfo *ToServerConvProc = NULL;
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static FmgrInfo *ToClientConvProc = NULL;
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/*
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* During backend startup we can't set client encoding because we (a)
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* can't look up the conversion functions, and (b) may not know the database
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@ -70,11 +84,7 @@ int
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SetClientEncoding(int encoding, bool doit)
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{
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int current_server_encoding;
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Oid to_server_proc,
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to_client_proc;
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FmgrInfo *to_server;
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FmgrInfo *to_client;
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MemoryContext oldcontext;
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ListCell *lc;
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if (!PG_VALID_FE_ENCODING(encoding))
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return -1;
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@ -101,79 +111,117 @@ SetClientEncoding(int encoding, bool doit)
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ClientEncoding = &pg_enc2name_tbl[encoding];
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ToServerConvProc = NULL;
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ToClientConvProc = NULL;
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if (MbProcContext)
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MemoryContextReset(MbProcContext);
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}
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return 0;
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}
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/*
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* If we're not inside a transaction then we can't do catalog lookups, so
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* fail. After backend startup, this could only happen if we are
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* re-reading postgresql.conf due to SIGHUP --- so basically this just
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* constrains the ability to change client_encoding on the fly from
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* postgresql.conf. Which would probably be a stupid thing to do anyway.
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*/
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if (!IsTransactionState())
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return -1;
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/*
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* Look up the conversion functions.
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*/
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to_server_proc = FindDefaultConversionProc(encoding,
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current_server_encoding);
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if (!OidIsValid(to_server_proc))
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return -1;
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to_client_proc = FindDefaultConversionProc(current_server_encoding,
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encoding);
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if (!OidIsValid(to_client_proc))
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return -1;
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/*
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* Done if not wanting to actually apply setting.
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*/
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if (!doit)
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return 0;
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/* Before loading the new fmgr info, remove the old info, if any */
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ToServerConvProc = NULL;
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ToClientConvProc = NULL;
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if (MbProcContext != NULL)
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if (IsTransactionState())
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{
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MemoryContextReset(MbProcContext);
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/*
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* If we're in a live transaction, it's safe to access the catalogs,
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* so look up the functions. We repeat the lookup even if the info
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* is already cached, so that we can react to changes in the contents
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* of pg_conversion.
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*/
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Oid to_server_proc,
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to_client_proc;
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ConvProcInfo *convinfo;
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MemoryContext oldcontext;
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to_server_proc = FindDefaultConversionProc(encoding,
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current_server_encoding);
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if (!OidIsValid(to_server_proc))
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return -1;
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to_client_proc = FindDefaultConversionProc(current_server_encoding,
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encoding);
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if (!OidIsValid(to_client_proc))
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return -1;
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/*
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* Done if not wanting to actually apply setting.
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*/
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if (!doit)
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return 0;
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/*
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* Load the fmgr info into TopMemoryContext (could still fail here)
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*/
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convinfo = (ConvProcInfo *) MemoryContextAlloc(TopMemoryContext,
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sizeof(ConvProcInfo));
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convinfo->s_encoding = current_server_encoding;
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convinfo->c_encoding = encoding;
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fmgr_info_cxt(to_server_proc, &convinfo->to_server_info,
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TopMemoryContext);
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fmgr_info_cxt(to_client_proc, &convinfo->to_client_info,
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TopMemoryContext);
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/* Attach new info to head of list */
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oldcontext = MemoryContextSwitchTo(TopMemoryContext);
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ConvProcList = lcons(convinfo, ConvProcList);
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MemoryContextSwitchTo(oldcontext);
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/*
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* Everything is okay, so apply the setting.
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*/
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ClientEncoding = &pg_enc2name_tbl[encoding];
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ToServerConvProc = &convinfo->to_server_info;
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ToClientConvProc = &convinfo->to_client_info;
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/*
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* Remove any older entry for the same encoding pair (this is just
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* to avoid memory leakage).
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*/
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foreach(lc, ConvProcList)
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{
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ConvProcInfo *oldinfo = (ConvProcInfo *) lfirst(lc);
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if (oldinfo == convinfo)
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continue;
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if (oldinfo->s_encoding == convinfo->s_encoding &&
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oldinfo->c_encoding == convinfo->c_encoding)
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{
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ConvProcList = list_delete_ptr(ConvProcList, oldinfo);
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pfree(oldinfo);
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break; /* need not look further */
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}
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}
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return 0; /* success */
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}
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else
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{
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/*
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* This is the first time through, so create the context. Make it a
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* child of TopMemoryContext so that these values survive across
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* transactions.
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* If we're not in a live transaction, the only thing we can do
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* is restore a previous setting using the cache. This covers all
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* transaction-rollback cases. The only case it might not work for
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* is trying to change client_encoding on the fly by editing
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* postgresql.conf and SIGHUP'ing. Which would probably be a stupid
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* thing to do anyway.
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*/
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MbProcContext = AllocSetContextCreate(TopMemoryContext,
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"MbProcContext",
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ALLOCSET_SMALL_MINSIZE,
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ALLOCSET_SMALL_INITSIZE,
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ALLOCSET_SMALL_MAXSIZE);
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foreach(lc, ConvProcList)
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{
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ConvProcInfo *oldinfo = (ConvProcInfo *) lfirst(lc);
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if (oldinfo->s_encoding == current_server_encoding &&
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oldinfo->c_encoding == encoding)
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{
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if (doit)
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{
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ClientEncoding = &pg_enc2name_tbl[encoding];
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ToServerConvProc = &oldinfo->to_server_info;
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ToClientConvProc = &oldinfo->to_client_info;
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}
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return 0;
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}
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}
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return -1; /* it's not cached, so fail */
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}
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/* Load the fmgr info into MbProcContext */
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oldcontext = MemoryContextSwitchTo(MbProcContext);
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to_server = palloc(sizeof(FmgrInfo));
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to_client = palloc(sizeof(FmgrInfo));
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fmgr_info(to_server_proc, to_server);
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fmgr_info(to_client_proc, to_client);
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MemoryContextSwitchTo(oldcontext);
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ClientEncoding = &pg_enc2name_tbl[encoding];
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ToServerConvProc = to_server;
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ToClientConvProc = to_client;
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return 0;
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}
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/*
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* Initialize client encoding if necessary.
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* called from InitPostgres() once during backend starting up.
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* called from InitPostgres() once during backend startup.
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*/
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void
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InitializeClientEncoding(void)
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@ -196,7 +244,8 @@ InitializeClientEncoding(void)
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}
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/*
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* returns the current client encoding */
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* returns the current client encoding
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*/
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int
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pg_get_client_encoding(void)
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{
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@ -511,10 +560,9 @@ pg_server_to_client(const char *s, int len)
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/*
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* Perform default encoding conversion using cached FmgrInfo. Since
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* this function does not access database at all, it is safe to call
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* outside transactions. Explicit setting client encoding required
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* before calling this function. Otherwise no conversion is
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* performed.
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*/
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* outside transactions. If the conversion has not been set up by
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* SetClientEncoding(), no conversion is performed.
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*/
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static char *
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perform_default_encoding_conversion(const char *src, int len, bool is_client_to_server)
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{
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@ -919,12 +967,6 @@ pg_bind_textdomain_codeset(const char *domainname, int encoding)
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#endif
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}
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void
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SetDefaultClientEncoding(void)
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{
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ClientEncoding = &pg_enc2name_tbl[GetDatabaseEncoding()];
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}
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int
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GetDatabaseEncoding(void)
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{
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@ -6,7 +6,7 @@
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* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/mb/pg_wchar.h,v 1.87 2009/03/09 00:01:32 alvherre Exp $
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* $PostgreSQL: pgsql/src/include/mb/pg_wchar.h,v 1.88 2009/04/02 17:30:53 tgl Exp $
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*
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* NOTES
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* This is used both by the backend and by libpq, but should not be
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@ -383,7 +383,6 @@ extern size_t wchar2char(char *to, const wchar_t *from, size_t tolen);
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extern size_t char2wchar(wchar_t *to, size_t tolen, const char *from, size_t fromlen);
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#endif
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extern void SetDefaultClientEncoding(void);
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extern int SetClientEncoding(int encoding, bool doit);
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extern void InitializeClientEncoding(void);
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extern int pg_get_client_encoding(void);
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