Обсуждение: Can't replace default converter.

Hello!

There is a database in KOI8-R encoding. And we have a client who is 
querying the database:
set client_encoding TO 'ALT'
and then he write some data into the database.
I have a problem with some symbols which exists in ALT encoding and 
which are absent in KOI8-R encoding. As result, during inserting strings 
with such symbols postgresql returns an error, for example:
ERROR: character 0xfc of encoding "ALT" has no equivalent in 
"MULE_INTERNAL"
I've decided to write my own converter, so here is my code:

[code]

#include <postgres.h>
#include <fmgr.h>


#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif

PG_FUNCTION_INFO_V1(fix_alt_to_koi8r);
PG_FUNCTION_INFO_V1(fix_koi8r_to_alt);

Datum
fix_alt_to_koi8r(PG_FUNCTION_ARGS)
{      elog(NOTICE,"ALT_TO_KOI8");   unsigned char *src  = PG_GETARG_CSTRING(*2*);   unsigned char *dest =
PG_GETARG_CSTRING(*3*);  int        len = PG_GETARG_INT32(*4*);
 
   Assert(PG_GETARG_INT32(*0*) == PG_ALT);   Assert(PG_GETARG_INT32(*1*) == PG_KOI8R);   Assert(len >= *0*);


      static const unsigned char convert866toKOI8[] = {              
*0*,*1*,*2*,*3*,*4*,*5*,*6*,*7*,*8*,*9*,*10*,*11*,*12*,*13*,*14*,*15*,              
*16*,*17*,*18*,*19*,*20*,*21*,*22*,*23*,*24*,*25*,*26*,*27*,*28*,*29*,*30*,*31*, 
              
*32*,*33*,*34*,*35*,*36*,*37*,*38*,*39*,*40*,*41*,*42*,*43*,*44*,*45*,*46*,*47*, 
              
*48*,*49*,*50*,*51*,*52*,*53*,*54*,*55*,*56*,*57*,*58*,*59*,*60*,*61*,*62*,*63*, 
              
*64*,*65*,*66*,*67*,*68*,*69*,*70*,*71*,*72*,*73*,*74*,*75*,*76*,*77*,*78*,*79*, 
              
*80*,*81*,*82*,*83*,*84*,*85*,*86*,*87*,*88*,*89*,*90*,*91*,*92*,*93*,*94*,*95*, 
              
*96*,*97*,*98*,*99*,*100*,*101*,*102*,*103*,*104*,*105*,*106*,*107*,*108*,*109*,*110*,*111*, 
              
*112*,*113*,*114*,*115*,*116*,*117*,*118*,*119*,*120*,*121*,*122*,*123*,*124*,*125*,*126*,*127*, 
              
*225*,*226*,*247*,*231*,*228*,*229*,*246*,*250*,*233*,*234*,*235*,*236*,*237*,*238*,*239*,*240*, 
              
*242*,*243*,*244*,*245*,*230*,*232*,*227*,*254*,*251*,*253*,*255*,*249*,*248*,*252*,*224*,*241*, 
              
*193*,*194*,*215*,*199*,*196*,*197*,*214*,*218*,*201*,*202*,*203*,*204*,*205*,*206*,*207*,*208*, 
              
*210*,*211*,*212*,*213*,*198*,*200*,*195*,*222*,*219*,*221*,*223*,*217*,*216*,*220*,*192*,*209*, 
              
*180*,*164*,*183*,*167*,*196*,*197*,*198*,*199*,*200*,*201*,*202*,*203*,*204*,*205*,*206*,*207*, 
              
*208*,*209*,*210*,*211*,*212*,*213*,*214*,*215*,*216*,*217*,*218*,*219*,*220*,*221*,*222*,*223*, 
              
*210*,*211*,*212*,*213*,*198*,*200*,*195*,*222*,*219*,*221*,*223*,*217*,*216*,*220*,*192*,*209*, 
          
*179*,*241*,*242*,*243*,*244*,*245*,*246*,*247*,*248*,*249*,*250*,*251*,*252*,*253*,*254*,*255* 
      };


   while(len){       *dest = convert866toKOI8[(unsigned char)(*src)];       ++src;       ++dest;       --len;   }
   PG_RETURN_VOID();
}



Datum
fix_koi8r_to_alt(PG_FUNCTION_ARGS)
{      elog(NOTICE,"KOI8_TO_ALT");   unsigned char *src  = PG_GETARG_CSTRING(*2*);   unsigned char *dest =
PG_GETARG_CSTRING(*3*);  int        len = PG_GETARG_INT32(*4*);
 
   Assert(PG_GETARG_INT32(*0*) == PG_KOI8R);   Assert(PG_GETARG_INT32(*1*) == PG_ALT);   Assert(len >= *0*);


      static const unsigned char KOI8to866[] = {          
*0*,*1*,*2*,*3*,*4*,*5*,*6*,*7*,*8*,*9*,*10*,*11*,*12*,*13*,*14*,*15*,          
*16*,*17*,*18*,*19*,*20*,*21*,*22*,*23*,*24*,*25*,*26*,*27*,*28*,*29*,*30*,*31*, 
          
*32*,*33*,*34*,*35*,*36*,*37*,*38*,*39*,*40*,*41*,*42*,*43*,*44*,*45*,*46*,*47*, 
          
*48*,*49*,*50*,*51*,*52*,*53*,*54*,*55*,*56*,*57*,*58*,*59*,*60*,*61*,*62*,*63*, 
          
*64*,*65*,*66*,*67*,*68*,*69*,*70*,*71*,*72*,*73*,*74*,*75*,*76*,*77*,*78*,*79*, 
          
*80*,*81*,*82*,*83*,*84*,*85*,*86*,*87*,*88*,*89*,*90*,*91*,*92*,*93*,*94*,*95*, 
          
*96*,*97*,*98*,*99*,*100*,*101*,*102*,*103*,*104*,*105*,*106*,*107*,*108*,*109*,*110*,*111*, 
          
*112*,*113*,*114*,*115*,*116*,*117*,*118*,*119*,*120*,*121*,*122*,*123*,*124*,*125*,*126*,*255*, 
          
*32*,*32*,*32*,*32*,*32*,*32*,*32*,*32*,*32*,*32*,*32*,*32*,*32*,*32*,*32*,*32*, 
          
*32*,*32*,*32*,*32*,*32*,*249*,*32*,*32*,*32*,*32*,*32*,*32*,*248*,*32*,*32*,*32*, 
          
*32*,*32*,*32*,*241*,*193*,*32*,*105*,*195*,*32*,*32*,*32*,*32*,*32*,*32*,*32*,*244*, 
          
*32*,*32*,*32*,*240*,*192*,*32*,*73*,*194*,*252*,*32*,*32*,*32*,*32*,*32*,*32*,*32*, 
          
*238*,*160*,*161*,*230*,*164*,*165*,*228*,*163*,*229*,*168*,*169*,*170*,*171*,*172*,*173*,*174*, 
          
*175*,*239*,*224*,*225*,*226*,*227*,*166*,*162*,*236*,*235*,*167*,*232*,*237*,*233*,*231*,*234*, 
          
*158*,*128*,*129*,*150*,*132*,*133*,*148*,*131*,*149*,*136*,*137*,*138*,*139*,*140*,*141*,*142*, 
          
*143*,*159*,*144*,*145*,*146*,*147*,*134*,*130*,*156*,*155*,*135*,*152*,*157*,*153*,*151*,*154*       };


   while(len){       *dest = KOI8to866[(unsigned char)(*src)];       ++src;       ++dest;       --len;   }
   PG_RETURN_VOID();

[/code]

I has copied this library into $libdir/funcs and I was trying to install 
the new converter instead of the old one,  in two directions alt->koi8 
and koi8->alt:

[code]

db_server=# CREATE FUNCTION 
fix_koi8r_to_alt(integer,integer,cstring,internal,integer) RETURNS 
integer AS '$libdir/funcs/fix_conv.so','fix_koi8r_to_alt' LANGUAGE C 
STRICT;
CREATE FUNCTION
db_server=# CREATE FUNCTION 
fix_alt_to_koi8r(integer,integer,cstring,internal,integer) RETURNS 
integer AS '$libdir/funcs/fix_conv.so','fix_alt_to_koi8r' LANGUAGE C 
STRICT;
CREATE FUNCTION
db_server=# CREATE DEFAULT CONVERSION koi2alt FOR 'KOI8' TO 'ALT' FROM 
fix_koi8r_to_alt;
CREATE CONVERSION
db_server=# CREATE DEFAULT CONVERSION alt2koi FOR 'ALT' TO 'KOI8' FROM 
fix_alt_to_koi8r;
CREATE CONVERSION
db_server=# set client_encoding to 'alt';

[/code]

I thought, that was all, but it was not. During the insert of 'bad' 
symbol in the test table i had the same error:
ERROR:  character 0xfc of encoding "ALT" has no equivalent in 
"MULE_INTERNAL"

I think that my conversion functions are not used. I saw in table 
pg_conversion:         conname           | connamespace | conowner | conforencoding | 
contoencoding |     conproc       | condefault         koi8_r_to_windows_866 |         *11* |        *1*    
|            *21*        |               *23*   |   koi8r_to_alt    | t          koi2alt               |         *2200*
    |          *1*  
 
|         *21*          |           *23*       | fix_koi8r_to_alt | t          windows_866_to_koi8_r         *11*
|   *1*     
 
|              *23*     |             *21*     | alt_to_koi8r      | t          alt2koi                    |
*2200*|        *1*    
 
|            *23*        |     *21*               | fix_alt_to_koi8r | t

and deleted two standard conversion functions:
[code]
db_server=# DROP CONVERSION koi8_r_to_windows_866;
DROP CONVERSION
db_server=# DROP CONVERSION windows_866_to_koi8_r;
DROP CONVERSION
[/code]

leaving only my own conversion functions.After this, when I'm trying to 
set the client encoding to ALT I got an error:

db_server=# set client_encoding to 'alt';
server closed the connection unexpectedly      This probably means the server terminated abnormally      before or
whileprocessing the request.
 
The connection to the server was lost. Attempting reset: Failed.
!> 

Is anyone can tell me what I'm doing wrong?
Thanks.

>      elog(NOTICE,"ALT_TO_KOI8");
>   unsigned char *src  = PG_GETARG_CSTRING(*2*);
>   unsigned char *dest = PG_GETARG_CSTRING(*3*);
>   int        len = PG_GETARG_INT32(*4*);

I don't think this is even valid C code?  Confused.

> Is anyone can tell me what I'm doing wrong?

select pg_backend_pid();
gdb -p $PID

...Robert

Roman <Roman_Khlystik@ukr.net> writes:
> db_server=# set client_encoding to 'alt';
> server closed the connection unexpectedly
>        This probably means the server terminated abnormally
>        before or while processing the request.
> The connection to the server was lost. Attempting reset: Failed.

> Is anyone can tell me what I'm doing wrong?

Two suggestions:

1. Use the latest release (from two weeks ago).  You are probably
tickling the bug that causes a failure in an output converter to
become an infinite recursion.

2. Don't try to replace the output converter.  You don't seem to
need that for your stated problem, and doing so exposes you to
problems in figuring out what's going wrong.

Also, yes, you will need to drop the system's conversion function
(or else mess with your search_path to make yours be found first).
        regards, tom lane