tmux-mem-cpu-load/common/getsysctl.h

/*
 * Copyright 2012 Matthew McCormick
 * Copyright 2013 Justin Crawford <Justasic@gmail.com>
 * Copyright 2015 Pawel 'l0ner' Soltys
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// Based on: github.com/freebsd/freebsd/blob/master/usr.bin/top/machine.c
// Based on: Apple.cpp for load_string/mem_string and apple's documentation

#ifndef BSD_METER_COMMON_H_
#define BSD_METER_COMMON_H_

#include <iostream>
#include <cerrno>
#include <sys/sysctl.h>
#include <sys/types.h>
#include <cstdlib>  //exit()
#include <string.h> //strerror()

#define GETSYSCTL(name, var) getsysctl(name, &(var), sizeof(var))
static inline void getsysctl( const char *name, void *ptr, size_t len )
{
  size_t nlen = len;

  if( sysctlbyname( name, ptr, &nlen, NULL, 0 ) == -1 )
  {
    std::cerr << "sysctl(" << name << "...) failed: " << strerror( errno )
      << std::endl;
    exit( EXIT_FAILURE );
  }

  if( nlen != len )
  {
    std::cerr << "sysctl(" << name << "...) expected " 
      << static_cast<unsigned long>( len ) << " bytes, got "
      << static_cast<unsigned long>( nlen ) << " bytes\n";
    //exit( 23 );
  }
}

#endif