/* * linux/kernel/sys.c * * (C) 1991 Linus Torvalds */
#include <errno.h>
#include <linux/sched.h> #include <linux/tty.h> #include <linux/kernel.h> #include <asm/segment.h> #include <sys/times.h> #include <sys/utsname.h> //返回ENOSYS的函数,表明本系统版本还没有实现的函数
int sys_ftime()//返回时间日期
{ return -ENOSYS; }
int sys_break()//
{ return -ENOSYS; }
int sys_ptrace()//当前进程对子进程进行调试
{ return -ENOSYS; }
int sys_stty()//修改并打引终端行设置
{ return -ENOSYS; }
int sys_gtty()//取得终端行信息
{ return -ENOSYS; }
int sys_rename()//修改文件名
{ return -ENOSYS; }
int sys_prof()//程序执行时间区域。
{ return -ENOSYS; }
int sys_setregid(int rgid, int egid)//设置当前任务的实际以及有效组ID
{ if (rgid>0) { if ((current->gid == rgid) || suser())//是否为超级用户
current->gid = rgid; else return(-EPERM); } if (egid>0) { if ((current->gid == egid) || (current->egid == egid) || (current->sgid == egid) || suser())//是否为超级用户
current->egid = egid; else return(-EPERM); } return 0; }
int sys_setgid(int gid)//设置进程组号
{ return(sys_setregid(gid, gid)); }
int sys_acct()//打开关闭进程记帐功能
{ return -ENOSYS; }
int sys_phys()//映射任意物理内存到进程的虚拟空间
{ return -ENOSYS; }
int sys_lock()//
{ return -ENOSYS; }
int sys_mpx()//
{ return -ENOSYS; }
int sys_ulimit()//
{ return -ENOSYS; }
int sys_time(long * tloc)//取当前时间,从1970年1月1日0点0分0秒开始
{ int i;
i = CURRENT_TIME; if (tloc) { verify_area(tloc,4);//验证内存容量
put_fs_long(i,(unsigned long *)tloc);//存入数据 段tloc中
} return i; }
/* * Unprivileged users may change the real user id to the effective uid * or vice versa. */ int sys_setreuid(int ruid, int euid)//设置进程的实际以及有效的用户ID
{ int old_ruid = current->uid; if (ruid>0) { if ((current->euid==ruid) || (old_ruid == ruid) || suser())//超级用户
current->uid = ruid; else return(-EPERM); } if (euid>0) { if ((old_ruid == euid) || (current->euid == euid) || suser())//超级用户
current->euid = euid; else { current->uid = old_ruid; return(-EPERM); } } return 0; }
int sys_setuid(int uid)//设置用户ID
{ return(sys_setreuid(uid, uid)); }
int sys_stime(long * tptr)//设置系统开机时间,参数tptr为从1970年1月1日0点0分0秒开始的时间值
{ if (!suser()) return -EPERM; startup_time = get_fs_long((unsigned long *)tptr) - jiffies/HZ;//当前时间值减去系统运行的时间值,也就是系统开机的霎时间值,其中HZ=100,为系统运行频率
return 0; }
int sys_times(struct tms * tbuf)//取得当前任务运行时间统计值
{ if (tbuf) { verify_area(tbuf,sizeof *tbuf); put_fs_long(current->utime,(unsigned long *)&tbuf->tms_utime);//用户运行时间
put_fs_long(current->stime,(unsigned long *)&tbuf->tms_stime);//内核运行时间
put_fs_long(current->cutime,(unsigned long *)&tbuf->tms_cutime);//子进程用户运行时间
put_fs_long(current->cstime,(unsigned long *)&tbuf->tms_cstime);//子进程内核运行时间
} return jiffies; }
int sys_brk(unsigned long end_data_seg)//修改数据段长度
{ if (end_data_seg >= current->end_code && end_data_seg < current->start_stack - 16384) current->brk = end_data_seg; return current->brk; }
/* * This needs some heave checking ... * I just haven't get the stomach for it. I also don't fully * understand sessions/pgrp etc. Let somebody who does explain it. */ int sys_setpgid(int pid, int pgid)//设置进程组ID
{ int i;
if (!pid) pid = current->pid; if (!pgid) pgid = current->pid; for (i=0 ; i<NR_TASKS ; i++) if (task[i] && task[i]->pid==pid) { if (task[i]->leader) return -EPERM; if (task[i]->session != current->session) return -EPERM; task[i]->pgrp = pgid; return 0; } return -ESRCH; }
int sys_getpgrp(void)//返回当前进程 的进程组号
{ return current->pgrp; }
int sys_setsid(void)//创建一个会 话
{ if (current->leader && !suser()) return -EPERM; current->leader = 1; current->session = current->pgrp = current->pid;//会话号==组号==进程号
current->tty = -1; return current->pgrp; }
int sys_uname(struct utsname * name)//取得系统相关信息
{ static struct utsname thisname = { "linux .0","nodename","release ","version ","machine " }; int i;
if (!name) return -ERROR; verify_area(name,sizeof *name);//验证内存空间
for(i=0;i<sizeof *name;i++) put_fs_byte(((char *) &thisname)[i],i+(char *) name);//将utsname 中的信息逐字节复制到用户缓冲区中
return 0; }
int sys_umask(int mask)//设置当前进程文件属性屏蔽码
{ int old = current->umask;
current->umask = mask & 0777; return (old); }
int sys_newfuction(void) {
}
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