postgresql/contrib/noupdate/noup.c
Bruce Momjian fd262dac8c > Sure send it in, we can put it in contrib. > > > > > I wrote a
real small function to revoke update on a column. The function >
> doesn't do anything > > fancy like checking user ids.  > > > >
I copied most of it from the refint.c in the contrib directory.
> > > > Should I post this somewhere? It really isn't very big.
> >

Here it is...

--
		| Email - rick@rpacorp.com
Rick Poleshuck  | Voice - (908) 653-1070      Fax - (908) 653-0265
		| Mail  - RPA Corporation |       - 308 Elizabeth
		Avenue, Cranford, New Jersey  07016
1998-06-16 17:53:44 +00:00

112 lines
2.9 KiB
C

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