freebsd-dev/lib/libc/gen/sysctlbyname.c
Stefan Eßer af7d105379 sysctlbyname(): restore access to user variables
The optimization of sysctlbyname() in commit d05b53e0ba had the
side-effect of not going through the fix-up for the user.* variables
in the previously called sysctl() function.

This lead to 0 or an empty strings being returned by sysctlbyname()
for all user.* variables.

An alternate implementation would store the user variables in the
kernel during system start-up. That would allow to remove the fix-up
code in the C library that is currently required to provide the actual
values.

This update restores the previous code path for the user.* variables
and keeps the performance optimization intact for all other variables.

Approved by:	mjg
Reviewed by:	kaktus
Differential Revision:	https://reviews.freebsd.org/D34171
2022-02-09 23:10:31 +01:00

58 lines
2.0 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright 2019 Pawel Biernacki, Mysterious Code Ltd.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/sysctl.h>
#include <string.h>
extern int __sysctlbyname(const char *name, size_t namelen, void *oldp,
size_t *oldlenp, const void *newp, size_t newlen);
int
sysctlbyname(const char *name, void *oldp, size_t *oldlenp,
const void *newp, size_t newlen)
{
size_t len;
int oid[2];
if (__predict_true(strncmp(name, "user.", 5) != 0)) {
len = strlen(name);
return (__sysctlbyname(name, len, oldp, oldlenp, newp,
newlen));
} else {
len = nitems(oid);
if (sysctlnametomib(name, oid, &len) == -1)
return (-1);
return (sysctl(oid, (u_int)len, oldp, oldlenp, newp,
newlen));
}
}