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Sourcecode: postgresql-8.4 version File versions

insert_username.c

/*
 * insert_username.c
 * $Modified: Thu Oct 16 08:13:42 1997 by brook $
 * $PostgreSQL: pgsql/contrib/spi/insert_username.c,v 1.17 2009/01/07 13:44:36 tgl Exp $
 *
 * insert user name in response to a trigger
 * usage:  insert_username (column_name)
 */
#include "postgres.h"

#include "catalog/pg_type.h"
#include "commands/trigger.h"
#include "executor/spi.h"
#include "miscadmin.h"
#include "utils/builtins.h"

PG_MODULE_MAGIC;

extern Datum insert_username(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(insert_username);

Datum
insert_username(PG_FUNCTION_ARGS)
{
      TriggerData *trigdata = (TriggerData *) fcinfo->context;
      Trigger    *trigger;          /* to get trigger name */
      int               nargs;                  /* # of arguments */
      Datum       newval;                 /* new value of column */
      char    **args;               /* arguments */
      char     *relname;            /* triggered relation name */
      Relation    rel;              /* triggered relation */
      HeapTuple   rettuple = NULL;
      TupleDesc   tupdesc;          /* tuple description */
      int               attnum;

      /* sanity checks from autoinc.c */
      if (!CALLED_AS_TRIGGER(fcinfo))
            /* internal error */
            elog(ERROR, "insert_username: not fired by trigger manager");
      if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
            /* internal error */
            elog(ERROR, "insert_username: cannot process STATEMENT events");
      if (TRIGGER_FIRED_AFTER(trigdata->tg_event))
            /* internal error */
            elog(ERROR, "insert_username: must be fired before event");

      if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
            rettuple = trigdata->tg_trigtuple;
      else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
            rettuple = trigdata->tg_newtuple;
      else
            /* internal error */
            elog(ERROR, "insert_username: cannot process DELETE events");

      rel = trigdata->tg_relation;
      relname = SPI_getrelname(rel);

      trigger = trigdata->tg_trigger;

      nargs = trigger->tgnargs;
      if (nargs != 1)
            /* internal error */
            elog(ERROR, "insert_username (%s): one argument was expected", relname);

      args = trigger->tgargs;
      tupdesc = rel->rd_att;

      attnum = SPI_fnumber(tupdesc, args[0]);

      if (attnum < 0)
            ereport(ERROR,
                        (errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
                         errmsg("\"%s\" has no attribute \"%s\"", relname, args[0])));

      if (SPI_gettypeid(tupdesc, attnum) != TEXTOID)
            ereport(ERROR,
                        (errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
                         errmsg("attribute \"%s\" of \"%s\" must be type TEXT",
                                    args[0], relname)));

      /* create fields containing name */
      newval = CStringGetTextDatum(GetUserNameFromId(GetUserId()));

      /* construct new tuple */
      rettuple = SPI_modifytuple(rel, rettuple, 1, &attnum, &newval, NULL);
      if (rettuple == NULL)
            /* internal error */
            elog(ERROR, "insert_username (\"%s\"): %d returned by SPI_modifytuple",
                   relname, SPI_result);

      pfree(relname);

      return PointerGetDatum(rettuple);
}

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