greenplumn superuser 源码
greenplumn superuser 代码
文件路径：/src/backend/utils/misc/superuser.c
/*-------------------------------------------------------------------------
*
* superuser.c
* The superuser() function. Determines if user has superuser privilege.
*
* All code should use either of these two functions to find out
* whether a given user is a superuser, rather than examining
* pg_authid.rolsuper directly, so that the escape hatch built in for
* the single-user case works.
*
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/utils/misc/superuser.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/htup_details.h"
#include "catalog/pg_authid.h"
#include "utils/inval.h"
#include "utils/syscache.h"
#include "storage/proc.h"
#include "miscadmin.h"
/*
* In common cases the same roleid (ie, the session or current ID) will
* be queried repeatedly. So we maintain a simple one-entry cache for
* the status of the last requested roleid. The cache can be flushed
* at need by watching for cache update events on pg_authid.
*/
static Oid last_roleid = InvalidOid; /* InvalidOid == cache not valid */
static bool last_roleid_is_super = false;
static bool roleid_callback_registered = false;
static void RoleidCallback(Datum arg, int cacheid, uint32 hashvalue);
/*
* The Postgres user running this command has Postgres superuser privileges
*/
bool
superuser(void)
{
return superuser_arg(GetUserId());
}
/*
* Is my role id a super user.
*/
bool
procRoleIsSuperuser(void)
{
return superuser_arg(MyProc->roleId);
}
/*
* The specified role has Postgres superuser privileges
*/
bool
superuser_arg(Oid roleid)
{
bool result;
HeapTuple rtup;
/* Quick out for cache hit */
if (OidIsValid(last_roleid) && last_roleid == roleid)
return last_roleid_is_super;
/* Special escape path in case you deleted all your users. */
if (!IsUnderPostmaster && roleid == BOOTSTRAP_SUPERUSERID)
return true;
/* OK, look up the information in pg_authid */
rtup = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid));
if (HeapTupleIsValid(rtup))
{
result = ((Form_pg_authid) GETSTRUCT(rtup))->rolsuper;
ReleaseSysCache(rtup);
}
else
{
/* Report "not superuser" for invalid roleids */
result = false;
}
/* If first time through, set up callback for cache flushes */
if (!roleid_callback_registered)
{
CacheRegisterSyscacheCallback(AUTHOID,
RoleidCallback,
(Datum) 0);
roleid_callback_registered = true;
}
/* Cache the result for next time */
last_roleid = roleid;
last_roleid_is_super = result;
return result;
}
/*
* RoleidCallback
* Syscache inval callback function
*/
static void
RoleidCallback(Datum arg, int cacheid, uint32 hashvalue)
{
/* Invalidate our local cache in case role's superuserness changed */
last_roleid = InvalidOid;
}
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