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  • Committer: alvherre
  • Date: 2005-12-16 21:24:52 UTC
  • Revision ID: svn-v4:db760fc0-0f08-0410-9d63-cc6633f64896:trunk:1
Initial import of the REL8_0_3 sources from the Pgsql CVS repository.

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contrib/noupdate/noup.c
 
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/*
 
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 * noup.c --    functions to remove update permission from a column
 
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 */
 
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#include "executor/spi.h"               /* this is what you need to work with SPI */
 
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#include "commands/trigger.h"   /* -"- and triggers */
 
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#include <ctype.h>                              /* tolower () */
 
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extern Datum noup(PG_FUNCTION_ARGS);
 
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/*
 
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 * noup () -- revoke permission on column
 
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 *
 
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 * Though it's called without args You have to specify referenced
 
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 * table/column while creating trigger:
 
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 * EXECUTE PROCEDURE noup ('col').
 
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 */
 
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PG_FUNCTION_INFO_V1(noup);
 
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Datum
 
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noup(PG_FUNCTION_ARGS)
 
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{
 
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        TriggerData *trigdata = (TriggerData *) fcinfo->context;
 
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        Trigger    *trigger;            /* to get trigger name */
 
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        int                     nargs;                  /* # of args specified in CREATE TRIGGER */
 
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        char      **args;                       /* arguments: column names and table name */
 
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        int                     nkeys;                  /* # of key columns (= nargs / 2) */
 
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        Datum      *kvals;                      /* key values */
 
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        Relation        rel;                    /* triggered relation */
 
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        HeapTuple       tuple = NULL;   /* tuple to return */
 
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        TupleDesc       tupdesc;                /* tuple description */
 
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        bool            isnull;                 /* to know is some column NULL or not */
 
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        int                     ret;
 
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        int                     i;
 
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        /*
 
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         * Some checks first...
 
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         */
 
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        /* Called by trigger manager ? */
 
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        if (!CALLED_AS_TRIGGER(fcinfo))
 
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                /* internal error */
 
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                elog(ERROR, "noup: not fired by trigger manager");
 
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        /* Should be called for ROW trigger */
 
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        if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
 
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                /* internal error */
 
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                elog(ERROR, "noup: can't process STATEMENT events");
 
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        /* Should not be called for INSERT */
 
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        if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
 
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                /* internal error */
 
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                elog(ERROR, "noup: can't process INSERT events");
 
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        /* Should not be called for DELETE */
 
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        else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
 
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                /* internal error */
 
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                elog(ERROR, "noup: can't process DELETE events");
 
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        /* check new Tuple */
 
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        tuple = trigdata->tg_newtuple;
 
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        trigger = trigdata->tg_trigger;
 
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        nargs = trigger->tgnargs;
 
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        args = trigger->tgargs;
 
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        nkeys = nargs;
 
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        rel = trigdata->tg_relation;
 
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        tupdesc = rel->rd_att;
 
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        /* Connect to SPI manager */
 
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        if ((ret = SPI_connect()) < 0)
 
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                /* internal error */
 
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                elog(ERROR, "noup: SPI_connect returned %d", ret);
 
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        /*
 
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         * We use SPI plan preparation feature, so allocate space to place key
 
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         * values.
 
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         */
 
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        kvals = (Datum *) palloc(nkeys * sizeof(Datum));
 
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        /* For each column in key ... */
 
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        for (i = 0; i < nkeys; i++)
 
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        {
 
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                /* get index of column in tuple */
 
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                int                     fnumber = SPI_fnumber(tupdesc, args[i]);
 
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                /* Bad guys may give us un-existing column in CREATE TRIGGER */
 
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                if (fnumber < 0)
 
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                        /* internal error */
 
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                        elog(ERROR, "noup: there is no attribute %s in relation %s",
 
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                                 args[i], SPI_getrelname(rel));
 
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                /* Well, get binary (in internal format) value of column */
 
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                kvals[i] = SPI_getbinval(tuple, tupdesc, fnumber, &isnull);
 
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                /*
 
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                 * If it's NOT NULL then cancel update
 
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                 */
 
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                if (!isnull)
 
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                {
 
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                        elog(WARNING, "%s: update not allowed", args[i]);
 
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                        SPI_finish();
 
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                        return PointerGetDatum(NULL);
 
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                }
 
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        }
 
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        SPI_finish();
 
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        return PointerGetDatum(tuple);
 
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}