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-rw-r--r--src/backend/libpq/be-fsstubs.c46
-rw-r--r--src/backend/storage/large_object/inv_api.c131
2 files changed, 115 insertions, 62 deletions
diff --git a/src/backend/libpq/be-fsstubs.c b/src/backend/libpq/be-fsstubs.c
index f600e140e78..016884e425f 100644
--- a/src/backend/libpq/be-fsstubs.c
+++ b/src/backend/libpq/be-fsstubs.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/libpq/be-fsstubs.c,v 1.77 2004/12/31 21:59:50 pgsql Exp $
+ * $PostgreSQL: pgsql/src/backend/libpq/be-fsstubs.c,v 1.78 2005/06/13 02:26:48 tgl Exp $
*
* NOTES
* This should be moved to a more appropriate place. It is here
@@ -195,6 +195,12 @@ lo_write(int fd, char *buf, int len)
return -1;
}
+ if ((cookies[fd]->flags & IFS_WRLOCK) == 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("large object descriptor %d was not opened for writing",
+ fd)));
+
Assert(fscxt != NULL);
currentContext = MemoryContextSwitchTo(fscxt);
@@ -236,26 +242,33 @@ lo_lseek(PG_FUNCTION_ARGS)
Datum
lo_creat(PG_FUNCTION_ARGS)
{
- int32 mode = PG_GETARG_INT32(0);
- LargeObjectDesc *lobjDesc;
- MemoryContext currentContext;
Oid lobjId;
+ MemoryContext currentContext;
+ /* do we actually need fscxt for this? */
CreateFSContext();
currentContext = MemoryContextSwitchTo(fscxt);
- lobjDesc = inv_create(mode);
+ lobjId = inv_create(InvalidOid);
- if (lobjDesc == NULL)
- {
- MemoryContextSwitchTo(currentContext);
- PG_RETURN_OID(InvalidOid);
- }
+ MemoryContextSwitchTo(currentContext);
+
+ PG_RETURN_OID(lobjId);
+}
+
+Datum
+lo_create(PG_FUNCTION_ARGS)
+{
+ Oid lobjId = PG_GETARG_OID(0);
+ MemoryContext currentContext;
- lobjId = lobjDesc->id;
+ /* do we actually need fscxt for this? */
+ CreateFSContext();
+
+ currentContext = MemoryContextSwitchTo(fscxt);
- inv_close(lobjDesc);
+ lobjId = inv_create(lobjId);
MemoryContextSwitchTo(currentContext);
@@ -403,12 +416,13 @@ lo_import(PG_FUNCTION_ARGS)
/*
* create an inversion object
*/
- lobj = inv_create(INV_READ | INV_WRITE);
- lobjOid = lobj->id;
+ lobjOid = inv_create(InvalidOid);
/*
- * read in from the filesystem and write to the inversion file
+ * read in from the filesystem and write to the inversion object
*/
+ lobj = inv_open(lobjOid, INV_WRITE);
+
while ((nbytes = FileRead(fd, buf, BUFSIZE)) > 0)
{
tmp = inv_write(lobj, buf, nbytes);
@@ -421,8 +435,8 @@ lo_import(PG_FUNCTION_ARGS)
errmsg("could not read server file \"%s\": %m",
fnamebuf)));
- FileClose(fd);
inv_close(lobj);
+ FileClose(fd);
PG_RETURN_OID(lobjOid);
}
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index 299e0756d1f..38734a5f9c3 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/large_object/inv_api.c,v 1.110 2005/04/14 20:03:25 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/large_object/inv_api.c,v 1.111 2005/06/13 02:26:49 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -114,6 +114,42 @@ close_lo_relation(bool isCommit)
}
+/*
+ * Same as pg_largeobject.c's LargeObjectExists(), except snapshot to
+ * read with can be specified.
+ */
+static bool
+myLargeObjectExists(Oid loid, Snapshot snapshot)
+{
+ bool retval = false;
+ Relation pg_largeobject;
+ ScanKeyData skey[1];
+ SysScanDesc sd;
+
+ /*
+ * See if we can find any tuples belonging to the specified LO
+ */
+ ScanKeyInit(&skey[0],
+ Anum_pg_largeobject_loid,
+ BTEqualStrategyNumber, F_OIDEQ,
+ ObjectIdGetDatum(loid));
+
+ pg_largeobject = heap_open(LargeObjectRelationId, AccessShareLock);
+
+ sd = systable_beginscan(pg_largeobject, LargeObjectLOidPNIndexId, true,
+ snapshot, 1, skey);
+
+ if (systable_getnext(sd) != NULL)
+ retval = true;
+
+ systable_endscan(sd);
+
+ heap_close(pg_largeobject, AccessShareLock);
+
+ return retval;
+}
+
+
static int32
getbytealen(bytea *data)
{
@@ -125,58 +161,44 @@ getbytealen(bytea *data)
/*
- * inv_create -- create a new large object.
+ * inv_create -- create a new large object
*
- * Arguments:
- * flags
+ * Arguments:
+ * lobjId - OID to use for new large object, or InvalidOid to pick one
*
- * Returns:
- * large object descriptor, appropriately filled in.
+ * Returns:
+ * OID of new object
+ *
+ * If lobjId is not InvalidOid, then an error occurs if the OID is already
+ * in use.
*/
-LargeObjectDesc *
-inv_create(int flags)
+Oid
+inv_create(Oid lobjId)
{
- Oid file_oid;
- LargeObjectDesc *retval;
-
/*
- * Allocate an OID to be the LO's identifier.
+ * Allocate an OID to be the LO's identifier, unless we were told
+ * what to use. In event of collision with an existing ID, loop
+ * to find a free one.
*/
- file_oid = newoid();
-
- /* Check for duplicate (shouldn't happen) */
- if (LargeObjectExists(file_oid))
- elog(ERROR, "large object %u already exists", file_oid);
+ if (!OidIsValid(lobjId))
+ {
+ do {
+ lobjId = newoid();
+ } while (LargeObjectExists(lobjId));
+ }
/*
* Create the LO by writing an empty first page for it in
- * pg_largeobject
+ * pg_largeobject (will fail if duplicate)
*/
- LargeObjectCreate(file_oid);
+ LargeObjectCreate(lobjId);
/*
- * Advance command counter so that new tuple will be seen by later
- * large-object operations in this transaction.
+ * Advance command counter to make new tuple visible to later operations.
*/
CommandCounterIncrement();
- /*
- * Prepare LargeObjectDesc data structure for accessing LO
- */
- retval = (LargeObjectDesc *) palloc(sizeof(LargeObjectDesc));
-
- retval->id = file_oid;
- retval->subid = GetCurrentSubTransactionId();
- retval->offset = 0;
-
- if (flags & INV_WRITE)
- retval->flags = IFS_WRLOCK | IFS_RDLOCK;
- else if (flags & INV_READ)
- retval->flags = IFS_RDLOCK;
- else
- elog(ERROR, "invalid flags: %d", flags);
-
- return retval;
+ return lobjId;
}
/*
@@ -190,11 +212,6 @@ inv_open(Oid lobjId, int flags)
{
LargeObjectDesc *retval;
- if (!LargeObjectExists(lobjId))
- ereport(ERROR,
- (errcode(ERRCODE_UNDEFINED_OBJECT),
- errmsg("large object %u does not exist", lobjId)));
-
retval = (LargeObjectDesc *) palloc(sizeof(LargeObjectDesc));
retval->id = lobjId;
@@ -202,12 +219,25 @@ inv_open(Oid lobjId, int flags)
retval->offset = 0;
if (flags & INV_WRITE)
+ {
+ retval->snapshot = SnapshotNow;
retval->flags = IFS_WRLOCK | IFS_RDLOCK;
+ }
else if (flags & INV_READ)
+ {
+ /* be sure to copy snap into fscxt */
+ retval->snapshot = CopySnapshot(ActiveSnapshot);
retval->flags = IFS_RDLOCK;
+ }
else
elog(ERROR, "invalid flags: %d", flags);
+ /* Can't use LargeObjectExists here because it always uses SnapshotNow */
+ if (!myLargeObjectExists(lobjId, retval->snapshot))
+ ereport(ERROR,
+ (errcode(ERRCODE_UNDEFINED_OBJECT),
+ errmsg("large object %u does not exist", lobjId)));
+
return retval;
}
@@ -218,6 +248,8 @@ void
inv_close(LargeObjectDesc *obj_desc)
{
Assert(PointerIsValid(obj_desc));
+ if (obj_desc->snapshot != SnapshotNow)
+ FreeSnapshot(obj_desc->snapshot);
pfree(obj_desc);
}
@@ -268,7 +300,7 @@ inv_getsize(LargeObjectDesc *obj_desc)
ObjectIdGetDatum(obj_desc->id));
sd = index_beginscan(lo_heap_r, lo_index_r,
- SnapshotNow, 1, skey);
+ obj_desc->snapshot, 1, skey);
/*
* Because the pg_largeobject index is on both loid and pageno, but we
@@ -379,7 +411,7 @@ inv_read(LargeObjectDesc *obj_desc, char *buf, int nbytes)
Int32GetDatum(pageno));
sd = index_beginscan(lo_heap_r, lo_index_r,
- SnapshotNow, 2, skey);
+ obj_desc->snapshot, 2, skey);
while ((tuple = index_getnext(sd, ForwardScanDirection)) != NULL)
{
@@ -470,6 +502,13 @@ inv_write(LargeObjectDesc *obj_desc, char *buf, int nbytes)
Assert(PointerIsValid(obj_desc));
Assert(buf != NULL);
+ /* enforce writability because snapshot is probably wrong otherwise */
+ if ((obj_desc->flags & IFS_WRLOCK) == 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("large object %u was not opened for writing",
+ obj_desc->id)));
+
if (nbytes <= 0)
return 0;
@@ -488,7 +527,7 @@ inv_write(LargeObjectDesc *obj_desc, char *buf, int nbytes)
Int32GetDatum(pageno));
sd = index_beginscan(lo_heap_r, lo_index_r,
- SnapshotNow, 2, skey);
+ obj_desc->snapshot, 2, skey);
oldtuple = NULL;
olddata = NULL;
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-31 01:11:21 +0000