93 lines
2.5 KiB
C
93 lines
2.5 KiB
C
/*
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* contrib/spi/insert_username.c
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*
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* insert user name in response to a trigger
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* usage: insert_username (column_name)
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*/
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#include "postgres.h"
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#include "access/htup_details.h"
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#include "catalog/pg_type.h"
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#include "commands/trigger.h"
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#include "executor/spi.h"
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#include "miscadmin.h"
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#include "utils/builtins.h"
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#include "utils/rel.h"
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PG_MODULE_MAGIC;
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PG_FUNCTION_INFO_V1(insert_username);
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Datum
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insert_username(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 arguments */
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Datum newval; /* new value of column */
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bool newnull; /* null flag */
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char **args; /* arguments */
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char *relname; /* triggered relation name */
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Relation rel; /* triggered relation */
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HeapTuple rettuple = NULL;
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TupleDesc tupdesc; /* tuple description */
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int attnum;
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/* sanity checks from autoinc.c */
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if (!CALLED_AS_TRIGGER(fcinfo))
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/* internal error */
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elog(ERROR, "insert_username: not fired by trigger manager");
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if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
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/* internal error */
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elog(ERROR, "insert_username: must be fired for row");
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if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
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/* internal error */
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elog(ERROR, "insert_username: must be fired before event");
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if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
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rettuple = trigdata->tg_trigtuple;
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else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
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rettuple = trigdata->tg_newtuple;
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else
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/* internal error */
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elog(ERROR, "insert_username: cannot process DELETE events");
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rel = trigdata->tg_relation;
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relname = SPI_getrelname(rel);
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trigger = trigdata->tg_trigger;
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nargs = trigger->tgnargs;
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if (nargs != 1)
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/* internal error */
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elog(ERROR, "insert_username (%s): one argument was expected", relname);
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args = trigger->tgargs;
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tupdesc = rel->rd_att;
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attnum = SPI_fnumber(tupdesc, args[0]);
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if (attnum <= 0)
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ereport(ERROR,
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(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
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errmsg("\"%s\" has no attribute \"%s\"", relname, args[0])));
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if (SPI_gettypeid(tupdesc, attnum) != TEXTOID)
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ereport(ERROR,
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(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
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errmsg("attribute \"%s\" of \"%s\" must be type TEXT",
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args[0], relname)));
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/* create fields containing name */
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newval = CStringGetTextDatum(GetUserNameFromId(GetUserId(), false));
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newnull = false;
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/* construct new tuple */
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rettuple = heap_modify_tuple_by_cols(rettuple, tupdesc,
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1, &attnum, &newval, &newnull);
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pfree(relname);
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return PointerGetDatum(rettuple);
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}
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