Hi,
On Mon, Mar 17, 2025 at 4:48 PM Steven Niu <niush...@gmail.com> wrote:
>
> 1. namespace.c, if relation->schemaname is pg_temp but myTempNamespace
> isn't set, the error information might be misleading. Consider checking
> OidIsValid(myTempNamespace) first.
Could you please clarify exactly which place in the code we are
talking about? I think we handle this case in the
LookupExplicitNamespace call (with all appropriate error information).
>
> 2."you have not any temporary relations" --> "you have no any temporary
> relations"
I am not an English speaker, but it seems that "have not" would be
more correct. Someone has to judge us :)
>
> 3. Regarding to the code "strncmp(nspname, "pg_temp", 7)", is it ok when
> the nspname contains something like "pg_temp_1234"? I think we should
> use strcmp instead of strncmp for exact matching.
Great catch! I'll fix it. Please, see v3 patch.
--
Best regards,
Daniil Davydov
From 74dc11678c55eb80ad48ad44fc77d770620ea0a7 Mon Sep 17 00:00:00 2001
From: Daniil Davidov <d.davy...@postgrespro.ru>
Date: Mon, 17 Mar 2025 15:43:15 +0700
Subject: [PATCH v3] Fix accessing other sessions temp tables
---
src/backend/catalog/namespace.c | 71 +++++++++++++++++++--------------
src/backend/nodes/makefuncs.c | 6 ++-
src/backend/parser/gram.y | 11 ++++-
3 files changed, 57 insertions(+), 31 deletions(-)
diff --git a/src/backend/catalog/namespace.c b/src/backend/catalog/namespace.c
index d97d632a7ef..b19c496a0ec 100644
--- a/src/backend/catalog/namespace.c
+++ b/src/backend/catalog/namespace.c
@@ -499,28 +499,40 @@ RangeVarGetRelidExtended(const RangeVar *relation, LOCKMODE lockmode,
*/
if (relation->relpersistence == RELPERSISTENCE_TEMP)
{
- if (!OidIsValid(myTempNamespace))
- relId = InvalidOid; /* this probably can't happen? */
- else
- {
- if (relation->schemaname)
- {
- Oid namespaceId;
+ Oid namespaceId;
- namespaceId = LookupExplicitNamespace(relation->schemaname, missing_ok);
+ if (relation->schemaname)
+ {
+ namespaceId = LookupExplicitNamespace(relation->schemaname, missing_ok);
+ if (namespaceId != myTempNamespace)
+ {
/*
- * For missing_ok, allow a non-existent schema name to
- * return InvalidOid.
+ * We don't allow users to access temp tables of other
+ * sessions (consider adding GUC for to allow to DROP such
+ * tables?).
*/
- if (namespaceId != myTempNamespace)
- ereport(ERROR,
- (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
- errmsg("temporary tables cannot specify a schema name")));
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("could not access temporary relations of other sessions")));
}
+ }
+ else
+ {
+ namespaceId = myTempNamespace;
- relId = get_relname_relid(relation->relname, myTempNamespace);
+ /*
+ * If this table was recognized as temporary, it means that we
+ * found it because backend's temporary namespace was specified
+ * in search_path. Thus, MyTempNamespace must contain valid oid.
+ */
+ Assert(OidIsValid(namespaceId));
}
+
+ if (missing_ok && !OidIsValid(namespaceId))
+ relId = InvalidOid;
+ else
+ relId = get_relname_relid(relation->relname, namespaceId);
}
else if (relation->schemaname)
{
@@ -3387,17 +3399,18 @@ LookupExplicitNamespace(const char *nspname, bool missing_ok)
Oid namespaceId;
AclResult aclresult;
- /* check for pg_temp alias */
+ /*
+ * If namespace specified in 'pg_temp' format (without owner backend id
+ * specification), we assume that this is our temporary namespace.
+ */
if (strcmp(nspname, "pg_temp") == 0)
{
- if (OidIsValid(myTempNamespace))
- return myTempNamespace;
+ if (!OidIsValid(myTempNamespace))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_SCHEMA_NAME),
+ errmsg("pg_temp was specified, but you have not any temporary relations")));
- /*
- * Since this is used only for looking up existing objects, there is
- * no point in trying to initialize the temp namespace here; and doing
- * so might create problems for some callers --- just fall through.
- */
+ return myTempNamespace;
}
namespaceId = get_namespace_oid(nspname, missing_ok);
@@ -3553,21 +3566,19 @@ get_namespace_oid(const char *nspname, bool missing_ok)
RangeVar *
makeRangeVarFromNameList(const List *names)
{
- RangeVar *rel = makeRangeVar(NULL, NULL, -1);
+ RangeVar *rel;
switch (list_length(names))
{
case 1:
- rel->relname = strVal(linitial(names));
+ rel = makeRangeVar(NULL, strVal(linitial(names)), -1);
break;
case 2:
- rel->schemaname = strVal(linitial(names));
- rel->relname = strVal(lsecond(names));
+ rel = makeRangeVar(strVal(linitial(names)), strVal(lsecond(names)), -1);
break;
case 3:
+ rel = makeRangeVar(strVal(lsecond(names)), strVal(lthird(names)), -1);
rel->catalogname = strVal(linitial(names));
- rel->schemaname = strVal(lsecond(names));
- rel->relname = strVal(lthird(names));
break;
default:
ereport(ERROR,
@@ -3774,6 +3785,8 @@ GetTempNamespaceProcNumber(Oid namespaceId)
return INVALID_PROC_NUMBER; /* no such namespace? */
if (strncmp(nspname, "pg_temp_", 8) == 0)
result = atoi(nspname + 8);
+ else if (strcmp(nspname, "pg_temp") == 0)
+ result = MyProcNumber;
else if (strncmp(nspname, "pg_toast_temp_", 14) == 0)
result = atoi(nspname + 14);
else
diff --git a/src/backend/nodes/makefuncs.c b/src/backend/nodes/makefuncs.c
index e2d9e9be41a..62edf24b5c2 100644
--- a/src/backend/nodes/makefuncs.c
+++ b/src/backend/nodes/makefuncs.c
@@ -478,10 +478,14 @@ makeRangeVar(char *schemaname, char *relname, int location)
r->schemaname = schemaname;
r->relname = relname;
r->inh = true;
- r->relpersistence = RELPERSISTENCE_PERMANENT;
r->alias = NULL;
r->location = location;
+ if (r->schemaname && strncmp(r->schemaname, "pg_temp", 7) == 0)
+ r->relpersistence = RELPERSISTENCE_TEMP;
+ else
+ r->relpersistence = RELPERSISTENCE_PERMANENT;
+
return r;
}
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 271ae26cbaf..f68948d475c 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -19424,7 +19424,11 @@ makeRangeVarFromAnyName(List *names, int position, core_yyscan_t yyscanner)
break;
}
- r->relpersistence = RELPERSISTENCE_PERMANENT;
+ if (r->schemaname && strncmp(r->schemaname, "pg_temp", 7) == 0)
+ r->relpersistence = RELPERSISTENCE_TEMP;
+ else
+ r->relpersistence = RELPERSISTENCE_PERMANENT;
+
r->location = position;
return r;
@@ -19464,6 +19468,11 @@ makeRangeVarFromQualifiedName(char *name, List *namelist, int location,
break;
}
+ if (r->schemaname && strncmp(r->schemaname, "pg_temp", 7) == 0)
+ r->relpersistence = RELPERSISTENCE_TEMP;
+ else
+ r->relpersistence = RELPERSISTENCE_PERMANENT;
+
return r;
}
--
2.43.0
