More cleanups for the recent large object permissions patch.

Rewrite or adjust various comments for clarity.  Remove one bogus comment that
doesn't reflect what the code actually does.  Improve the description of the
lo_compat_privileges option.

diff --git a/src/backend/catalog/aclchk.c b/src/backend/catalog/aclchk.c
index 809df7a573b9a240d38679f43032e2fdcf8bcbe5..b0aea415d2a830b65424ef07b6f802a28a0e63f2 100644 (file)
--- a/src/backend/catalog/aclchk.c
+++ b/src/backend/catalog/aclchk.c
@@ -4261,9 +4261,8 @@ pg_language_ownercheck(Oid lan_oid, Oid roleid)
 /*
  * Ownership check for a largeobject (specified by OID)
  *
- * Note that we have no candidate to call this routine with a certain
- * snapshot except for SnapshotNow, so we don't provide an interface
- * with _snapshot() version now.
+ * This is only used for operations like ALTER LARGE OBJECT that are always
+ * relative to SnapshotNow.
  */
 bool
 pg_largeobject_ownercheck(Oid lobj_oid, Oid roleid)

diff --git a/src/backend/catalog/pg_largeobject.c b/src/backend/catalog/pg_largeobject.c
index ada5b8829a5b902b448daafb88de1801d1e095ec..dfbf350d52ff8964405ebea79ca573d3ee577ef4 100644 (file)
--- a/src/backend/catalog/pg_largeobject.c
+++ b/src/backend/catalog/pg_largeobject.c
@@ -79,10 +79,8 @@ LargeObjectCreate(Oid loid)
 }
 
 /*
- * Drop a large object having the given LO identifier.
- *
- * When we drop a large object, it is necessary to drop both of metadata
- * and data pages in same time.
+ * Drop a large object having the given LO identifier.  Both the data pages
+ * and metadata must be dropped.
  */
 void
 LargeObjectDrop(Oid loid)
@@ -191,13 +189,12 @@ LargeObjectAlterOwner(Oid loid, Oid newOwnerId)
        if (!superuser())
        {
            /*
-            * The 'lo_compat_privileges' is not checked here, because we
-            * don't have any access control features in the 8.4.x series
-            * or earlier release.
-            * So, it is not a place we can define a compatible behavior.
+            * lo_compat_privileges is not checked here, because ALTER
+            * LARGE OBJECT ... OWNER did not exist at all prior to
+            * PostgreSQL 8.5.
+            *
+            * We must be the owner of the existing object.
             */
-
-           /* Otherwise, must be owner of the existing object */
            if (!pg_largeobject_ownercheck(loid, GetUserId()))
                ereport(ERROR,
                        (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
@@ -251,9 +248,8 @@ LargeObjectAlterOwner(Oid loid, Oid newOwnerId)
 /*
  * LargeObjectExists
  *
- * Currently, we don't use system cache to contain metadata of
- * large objects, because massive number of large objects can
- * consume not a small amount of process local memory.
+ * We don't use the system cache to for large object metadata, for fear of
+ * using too much local memory.
  *
  * Note that LargeObjectExists always scans the system catalog
  * with SnapshotNow, so it is unavailable to use to check

diff --git a/src/backend/commands/comment.c b/src/backend/commands/comment.c
index 8f8ecc781d903de1cdd3e72e6f80d72178305d32..ece2a307bf00a79e04c302c367fe06dd060b0ab7 100644 (file)
--- a/src/backend/commands/comment.c
+++ b/src/backend/commands/comment.c
@@ -1449,7 +1449,7 @@ CommentLargeObject(List *qualname, char *comment)
     *
     * See the comment in the inv_create() which describes
     * the reason why LargeObjectRelationId is used instead
-    * of the LargeObjectMetadataRelationId.
+    * of LargeObjectMetadataRelationId.
     */
    CreateComments(loid, LargeObjectRelationId, 0, comment);
 }

diff --git a/src/backend/utils/adt/acl.c b/src/backend/utils/adt/acl.c
index d57707f04bd8a9e5f29f889cdd3268b0f3e2b485..7e61eae57758f635a345b52e4b4c1f42b0abdfba 100644 (file)
--- a/src/backend/utils/adt/acl.c
+++ b/src/backend/utils/adt/acl.c
@@ -765,7 +765,6 @@ acldefault(GrantObjectType objtype, Oid ownerId)
            owner_default = ACL_ALL_RIGHTS_LANGUAGE;
            break;
        case ACL_OBJECT_LARGEOBJECT:
-           /* Grant SELECT,UPDATE by default, for now */
            world_default = ACL_NO_RIGHTS;
            owner_default = ACL_ALL_RIGHTS_LARGEOBJECT;
            break;

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 0376b164377f0f11d1771ff22b6b5a73a6e88dd9..b5307201ed8e37fad14b26402dbdc765dc4f4a8e 100644 (file)
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -1243,9 +1243,9 @@ static struct config_bool ConfigureNamesBool[] =
 
    {
        {"lo_compat_privileges", PGC_SUSET, COMPAT_OPTIONS_PREVIOUS,
-           gettext_noop("Enables backward compatibility in privilege checks on large objects"),
-           gettext_noop("When turned on, privilege checks on large objects perform "
-                        "with backward compatibility as 8.4.x or earlier releases.")
+           gettext_noop("Enables backward compatibility mode for privilege checks on large objects"),
+           gettext_noop("Skips privilege checks when reading or modifying large objects, "
+                        "for compatibility with PostgreSQL releases prior to 8.5.")
        },
        &lo_compat_privileges,
        false, NULL, NULL