freebsd-dev/lib/libutil/kinfo_getproc.c
Ed Maste 904c148f1c libutil: eliminate one syscall from kinfo_getproc
Previously we invoked the sysctl with a NULL buffer to query the size,
allocated a buffer, then invoked it again to fetch the data.

As we only handle the case where the sysctl provides data of the
expected size we can just allocate a correctly-sized buffer to begin
with.

Reported by:	Thomas Hurst via Twitter
Reviewed by:	kevans
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D35140
2022-05-06 20:06:09 -04:00

72 lines
2.1 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2009 Ulf Lilleengen
* All rights reserved.
*
* 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.
*
* $FreeBSD$
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/sysctl.h>
#include <sys/user.h>
#include <stdlib.h>
#include <string.h>
#include "libutil.h"
struct kinfo_proc *
kinfo_getproc(pid_t pid)
{
struct kinfo_proc *kipp;
int mib[4];
size_t len;
len = sizeof(*kipp);
kipp = malloc(len);
if (kipp == NULL)
return (NULL);
mib[0] = CTL_KERN;
mib[1] = KERN_PROC;
mib[2] = KERN_PROC_PID;
mib[3] = pid;
if (sysctl(mib, nitems(mib), kipp, &len, NULL, 0) < 0)
goto bad;
if (len != sizeof(*kipp))
goto bad;
if (kipp->ki_structsize != sizeof(*kipp))
goto bad;
if (kipp->ki_pid != pid)
goto bad;
return (kipp);
bad:
free(kipp);
return (NULL);
}