mirror_zfs/lib/libspl/libspl.c
Rob Norris 4d451bae8a libspl: hide global data objects
Currently libspl is a static archive that is linked into multiple shared
objects, which then re-export its symbols. We intend to fix this soon.

For the moment though, most programs shipped with OpenZFS depend on two
or more of these shared objects, and see the same symbols twice. For
functions this is not a problem, as they do not have any mutable state
and so the linker can simply select the first one and use that for all.

For global data objects however, each shared object will have direct
(non-relocatable) references to its own instance of the symbol, such
that changes on one will not necessarily be seen by the other. While
this shouldn't be a problem in practice as these reexported interfaces
are not supposed to be used, they are technically undefined behaviour in
C (C17 6.9.2) and are reported by ASAN as a violation of C++'s "One
Definition Rule".

To fix this, we hide these globals inside their compilation units, and
add access functions and macros as appropriate to preserve the existing
API (though not ABI).

Sponsored-by: https://despairlabs.com/sponsor/
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes #17861
2025-11-12 10:04:22 -08:00

68 lines
1.6 KiB
C

// SPDX-License-Identifier: CDDL-1.0
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or https://opensource.org/licenses/CDDL-1.0.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2018 by Delphix. All rights reserved.
* Copyright (c) 2016 Actifio, Inc. All rights reserved.
* Copyright (c) 2025, Klara, Inc.
* Copyright (c) 2025, Rob Norris <robn@despairlabs.com>
*/
#include <libspl.h>
#include <assert.h>
#include <unistd.h>
#include <sys/misc.h>
#include <sys/systm.h>
#include <sys/utsname.h>
#include "libspl_impl.h"
static uint64_t hw_physmem = 0;
static struct utsname hw_utsname = {};
uint64_t
libspl_physmem(void)
{
return (hw_physmem);
}
utsname_t *
utsname(void)
{
return (&hw_utsname);
}
void
libspl_init(void)
{
hw_physmem = sysconf(_SC_PHYS_PAGES);
VERIFY0(uname(&hw_utsname));
random_init();
}
void
libspl_fini(void)
{
random_fini();
}