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Orphaning that occurs with JDBC & ODBC. Contents: contrib/lo/Makefile contrib/lo/README contrib/lo/lo.c contrib/lo/lo.sql.in These are just test stuff - not essential contrib/lo/test.sql contrib/lo/drop.sql Peter Mount
214 lines
4.3 KiB
C
214 lines
4.3 KiB
C
/*
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* PostgreSQL type definitions for managed LargeObjects.
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*
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* $Id: lo.c,v 1.1 1998/06/16 07:07:11 momjian Exp $
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*
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*/
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#include <stdio.h>
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#include <postgres.h>
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#include <utils/palloc.h>
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/* Required for largeobjects */
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#include <libpq/libpq-fs.h>
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#include <libpq/be-fsstubs.h>
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/* Required for SPI */
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#include <executor/spi.h>
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/* Required for triggers */
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#include <commands/trigger.h>
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/* required for tolower() */
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/*
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* This is the internal storage format for managed large objects
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*
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*/
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typedef Oid Blob;
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/*
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* Various forward declarations:
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*/
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Blob *lo_in(char *str); /* Create from String */
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char *lo_out(Blob * addr); /* Output oid as String */
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Oid lo_oid(Blob * addr); /* Return oid as an oid */
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Blob *lo(Oid oid); /* Return Blob based on oid */
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HeapTuple lo_manage(void); /* Trigger handler */
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/*
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* This creates a large object, and set's its OID to the value in the
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* supplied string.
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*
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* If the string is empty, then a new LargeObject is created, and its oid
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* is placed in the resulting lo.
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*/
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Blob *
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lo_in(char *str)
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{
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Blob *result;
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Oid oid;
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int count;
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if (strlen(str) > 0)
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{
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count = sscanf(str, "%d", &oid);
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if (count < 1)
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{
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elog(ERROR, "lo_in: error in parsing \"%s\"", str);
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return (NULL);
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}
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if(oid < 0)
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{
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elog(ERROR, "lo_in: illegal oid \"%s\"", str);
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return (NULL);
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}
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}
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else
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{
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/*
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* There is no Oid passed, so create a new one
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*/
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oid = lo_creat(INV_READ|INV_WRITE);
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if(oid == InvalidOid)
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{
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elog(ERROR,"lo_in: InvalidOid returned from lo_creat");
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return (NULL);
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}
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}
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result = (Blob *) palloc(sizeof(Blob));
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*result = oid;
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return (result);
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}
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/*
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* This simply outputs the Oid of the Blob as a string.
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*/
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char *
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lo_out(Blob * addr)
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{
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char *result;
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if (addr == NULL)
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return (NULL);
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result = (char *) palloc(32);
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sprintf(result,"%d",*addr);
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return (result);
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}
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/*
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* This function converts Blob to oid.
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*
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* eg: select lo_export(raster::oid,'/path/file') from table;
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*
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*/
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Oid
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lo_oid(Blob * addr)
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{
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if(addr == NULL)
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return InvalidOid;
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return (Oid)(*addr);
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}
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/*
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* This function is used so we can convert oid's to lo's
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*
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* ie: insert into table values(lo_import('/path/file')::lo);
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*
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*/
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Blob *
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lo(Oid oid)
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{
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Blob *result = (Blob *) palloc(sizeof(Blob));
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*result = oid;
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return (result);
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}
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/*
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* This handles the trigger that protects us from orphaned large objects
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*/
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HeapTuple
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lo_manage(void)
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{
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int attnum; /* attribute number to monitor */
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char **args; /* Args containing attr name */
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TupleDesc tupdesc; /* Tuple Descriptor */
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HeapTuple rettuple; /* Tuple to be returned */
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bool isdelete; /* are we deleting? */
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HeapTuple newtuple=NULL; /* The new value for tuple */
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HeapTuple trigtuple; /* The original value of tuple */
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if (!CurrentTriggerData)
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elog(ERROR, "lo: triggers are not initialized");
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/*
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* Fetch some values from CurrentTriggerData
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*/
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newtuple = CurrentTriggerData->tg_newtuple;
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trigtuple = CurrentTriggerData->tg_trigtuple;
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tupdesc = CurrentTriggerData->tg_relation->rd_att;
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args = CurrentTriggerData->tg_trigger->tgargs;
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/* tuple to return to Executor */
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if (TRIGGER_FIRED_BY_UPDATE(CurrentTriggerData->tg_event))
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rettuple = newtuple;
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else
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rettuple = trigtuple;
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/* Are we deleting the row? */
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isdelete = TRIGGER_FIRED_BY_DELETE(CurrentTriggerData->tg_event);
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/* Were done with it */
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CurrentTriggerData = NULL;
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/* Get the column were interested in */
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attnum = SPI_fnumber(tupdesc,args[0]);
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/*
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* Handle updates
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*
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* Here, if the value of the monitored attribute changes, then the
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* large object associated with the original value is unlinked.
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*/
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if(newtuple!=NULL) {
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char *orig = SPI_getvalue(trigtuple,tupdesc,attnum);
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char *newv = SPI_getvalue(newtuple,tupdesc,attnum);
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if((orig != newv && (orig==NULL || newv==NULL)) || (orig!=NULL && newv!=NULL && strcmp(orig,newv)))
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lo_unlink(atoi(orig));
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if(newv)
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pfree(newv);
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if(orig)
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pfree(orig);
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}
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/*
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* Handle deleting of rows
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*
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* Here, we unlink the large object associated with the managed attribute
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*
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*/
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if(isdelete) {
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char *orig = SPI_getvalue(trigtuple,tupdesc,attnum);
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if(orig != NULL) {
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lo_unlink(atoi(orig));
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pfree(orig);
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}
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}
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return (rettuple);
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}
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