mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-12-27 08:39:28 +08:00
fd262dac8c
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
112 lines
2.9 KiB
C
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);
|
|
}
|