system.c

上一个上传的有问题,这个是好的。visopsys包括系统内核和GUI的全部SOURCE code ,还包括一些基本的docs文档。里面src子目录对应所有SOURCE code.对于想研究操作系统的朋

//
//  Visopsys
//  Copyright (C) 1998-2007 J. Andrew McLaughlin
// 
//  This program is free software; you can redistribute it and/or modify it
//  under the terms of the GNU General Public License as published by the Free
//  Software Foundation; either version 2 of the License, or (at your option)
//  any later version.
// 
//  This program is distributed in the hope that it will be useful, but
//  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
//  or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
//  for more details.
//  
//  You should have received a copy of the GNU General Public License along
//  with this program; if not, write to the Free Software Foundation, Inc.,
//  59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
//  system.c
//

// This is the standard "system" function, as found in standard C libraries.
// Unlike UNIX it does not execute a shell program to run the command, but
// rather passes the command and arguments straight to the kernel's loader.

#include <stdlib.h>
#include <sys/api.h>
#include <errno.h>


int system(const char *command)
{
  int status = 0;
  int privilege = 0;

  // Check params
  if (command == NULL)
    return (status = ERR_NULLPARAMETER);

  if (visopsys_in_kernel)
    return (errno = ERR_BUG);

  // What is my privilege level?
  privilege = multitaskerGetProcessPrivilege(multitaskerGetCurrentProcessId());
  if (privilege < 0)
    return (status = privilege);

  // Try to execute the command
  status = loaderLoadAndExec(command, privilege, 1 /* block */);

  return (status);
}