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/*
* PostgreSQL type definitions for managed LargeObjects.
*
* $Header: /cvsroot/pgsql/contrib/lo/lo.c,v 1.8 2001/03/22 03:59:09 momjian Exp $
*
*/
#include "postgres.h"
/* Required for largeobjects */
#include "libpq/libpq-fs.h"
#include "libpq/be-fsstubs.h"
/* Required for SPI */
#include "executor/spi.h"
/* Required for triggers */
#include "commands/trigger.h"
#define atooid(x) ((Oid) strtoul((x), NULL, 10))
/*
* This is the internal storage format for managed large objects
*
*/
typedef Oid Blob;
/*
* Various forward declarations:
*/
Blob *lo_in(char *str); /* Create from String */
char *lo_out(Blob * addr);/* Output oid as String */
Oid lo_oid(Blob * addr);/* Return oid as an oid */
Blob *lo(Oid oid); /* Return Blob based on oid */
Datum lo_manage(PG_FUNCTION_ARGS); /* Trigger handler */
/*
* This creates a large object, and sets its OID to the value in the
* supplied string.
*
* If the string is empty, then a new LargeObject is created, and its oid
* is placed in the resulting lo.
*/
Blob *
lo_in(char *str)
{
Blob *result;
Oid oid;
int count;
if (strlen(str) > 0)
{
count = sscanf(str, "%u", &oid);
if (count < 1)
elog(ERROR, "lo_in: error in parsing \"%s\"", str);
if (oid == InvalidOid)
elog(ERROR, "lo_in: illegal oid \"%s\"", str);
}
else
{
/*
* There is no Oid passed, so create a new one
*/
oid = DatumGetObjectId(DirectFunctionCall1(lo_creat,
Int32GetDatum(INV_READ | INV_WRITE)));
if (oid == InvalidOid)
elog(ERROR, "lo_in: InvalidOid returned from lo_creat");
}
result = (Blob *) palloc(sizeof(Blob));
*result = oid;
return (result);
}
/*
* This simply outputs the Oid of the Blob as a string.
*/
char *
lo_out(Blob * addr)
{
char *result;
if (addr == NULL)
return (NULL);
result = (char *) palloc(32);
sprintf(result, "%u", *addr);
return (result);
}
/*
* This function converts Blob to oid.
*
* eg: select lo_export(raster::oid,'/path/file') from table;
*
*/
Oid
lo_oid(Blob * addr)
{
if (addr == NULL)
return InvalidOid;
return (Oid) (*addr);
}
/*
* This function is used so we can convert oid's to lo's
*
* ie: insert into table values(lo_import('/path/file')::lo);
*
*/
Blob *
lo(Oid oid)
{
Blob *result = (Blob *) palloc(sizeof(Blob));
*result = oid;
return (result);
}
/*
* This handles the trigger that protects us from orphaned large objects
*/
PG_FUNCTION_INFO_V1(lo_manage);
Datum
lo_manage(PG_FUNCTION_ARGS)
{
TriggerData *trigdata = (TriggerData *) fcinfo->context;
int attnum; /* attribute number to monitor */
char **args; /* Args containing attr name */
TupleDesc tupdesc; /* Tuple Descriptor */
HeapTuple rettuple; /* Tuple to be returned */
bool isdelete; /* are we deleting? */
HeapTuple newtuple = NULL;/* The new value for tuple */
HeapTuple trigtuple; /* The original value of tuple */
if (!CALLED_AS_TRIGGER(fcinfo))
elog(ERROR, "lo: not fired by trigger manager");
/*
* Fetch some values from trigdata
*/
newtuple = trigdata->tg_newtuple;
trigtuple = trigdata->tg_trigtuple;
tupdesc = trigdata->tg_relation->rd_att;
args = trigdata->tg_trigger->tgargs;
/* tuple to return to Executor */
if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
rettuple = newtuple;
else
rettuple = trigtuple;
/* Are we deleting the row? */
isdelete = TRIGGER_FIRED_BY_DELETE(trigdata->tg_event);
/* Get the column were interested in */
attnum = SPI_fnumber(tupdesc, args[0]);
/*
* Handle updates
*
* Here, if the value of the monitored attribute changes, then the large
* object associated with the original value is unlinked.
*/
if (newtuple != NULL)
{
char *orig = SPI_getvalue(trigtuple, tupdesc, attnum);
char *newv = SPI_getvalue(newtuple, tupdesc, attnum);
if ((orig != newv && (orig == NULL || newv == NULL)) || (orig != NULL && newv != NULL && strcmp(orig, newv)))
DirectFunctionCall1(lo_unlink,
ObjectIdGetDatum(atooid(orig)));
if (newv)
pfree(newv);
if (orig)
pfree(orig);
}
/*
* Handle deleting of rows
*
* Here, we unlink the large object associated with the managed attribute
*
*/
if (isdelete)
{
char *orig = SPI_getvalue(trigtuple, tupdesc, attnum);
if (orig != NULL)
{
DirectFunctionCall1(lo_unlink,
ObjectIdGetDatum(atooid(orig)));
pfree(orig);
}
}
return PointerGetDatum(rettuple);
}
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