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/*
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* linux/kernel/sys.c
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*
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* (C) 1991 Linus Torvalds
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*/
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#include <errno.h>
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#include <linux/sched.h> //调度程序头文件。定义了任务结构task_struct,任务0的数据,
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//还有一些有关描述符参数设置和获取的嵌入式汇编函数宏语言
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#include <linux/tty.h>
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#include <linux/kernel.h> //内核头文件
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#include <asm/segment.h>
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#include <sys/times.h>
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#include <sys/utsname.h> //系统名称结构头文件
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#include <fcntl.h>
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int sys_ftime()
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{
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return -ENOSYS;
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}
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int sys_break()
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{
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return -ENOSYS;
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}
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int sys_ptrace()
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{
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return -ENOSYS;
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}
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int sys_stty()
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{
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return -ENOSYS;
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}
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int sys_gtty()
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{
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return -ENOSYS;
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}
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int sys_rename()
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{
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return -ENOSYS;
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}
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int sys_prof()
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{
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return -ENOSYS;
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}
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int sys_setregid(int rgid, int egid)
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{
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if (rgid>0) {
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if ((current->gid == rgid) ||
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suser())
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current->gid = rgid;
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else
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return(-EPERM);
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}
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if (egid>0) {
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if ((current->gid == egid) ||
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(current->egid == egid) ||
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suser()) {
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current->egid = egid;
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current->sgid = egid;
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} else
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return(-EPERM);
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}
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return 0;
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}
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//设置进程组号
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int sys_setgid(int gid)
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{
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/* return(sys_setregid(gid, gid)); */
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if (suser())
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current->gid = current->egid = current->sgid = gid;
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else if ((gid == current->gid) || (gid == current->sgid))
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current->egid = gid;
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else
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return -EPERM;
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return 0;
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}
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int sys_acct()
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{
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return -ENOSYS;
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}
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int sys_phys()
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{
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return -ENOSYS;
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}
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int sys_lock()
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{
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return -ENOSYS;
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}
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int sys_mpx()
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{
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return -ENOSYS;
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}
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int sys_ulimit()
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{
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return -ENOSYS;
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}
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//返回从1970年1月1号 开始记时的时间值(s)
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int sys_time(long * tloc)
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{
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int i;
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i = CURRENT_TIME;
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if (tloc) {
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verify_area(tloc,4);
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put_fs_long(i,(unsigned long *)tloc); //把时间值存储到用户空间
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//段寄存器fs被默认地指向用户数据空间，因此此函数可利用fs段寄存器来访问用户空间中的值
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}
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return i;
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}
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/*
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* Unprivileged users may change the real user id to the effective uid
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* or vice versa.
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*/
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int sys_setreuid(int ruid, int euid)
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{
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int old_ruid = current->uid;
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if (ruid>0) {
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if ((current->euid==ruid) ||
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(old_ruid == ruid) ||
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suser())
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current->uid = ruid;
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else
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return(-EPERM);
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}
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if (euid>0) {
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if ((old_ruid == euid) ||
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(current->euid == euid) ||
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suser()) {
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current->euid = euid;
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current->suid = euid;
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} else {
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current->uid = old_ruid;
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return(-EPERM);
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}
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}
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return 0;
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}
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int sys_setuid(int uid)
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{
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/* return(sys_setreuid(uid, uid)); */
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if (suser())
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current->uid = current->euid = current->suid = uid;
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else if ((uid == current->uid) || (uid == current->suid))
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current->euid = uid;
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else
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return -EPERM;
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return(0);
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}
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int sys_stime(long * tptr)
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{
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if (!suser())
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return -EPERM;
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startup_time = get_fs_long((unsigned long *)tptr) - jiffies/HZ;
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return 0;
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}
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//获取当前任务运行时间统计值
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int sys_times(struct tms * tbuf)
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{
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if (tbuf) {
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verify_area(tbuf,sizeof *tbuf);
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put_fs_long(current->utime,(unsigned long *)&tbuf->tms_utime);
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put_fs_long(current->stime,(unsigned long *)&tbuf->tms_stime);
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put_fs_long(current->cutime,(unsigned long *)&tbuf->tms_cutime);
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put_fs_long(current->cstime,(unsigned long *)&tbuf->tms_cstime);
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}
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return jiffies;
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}
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//设置程序在内存中的末端位置
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int sys_brk(unsigned long end_data_seg)
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{
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//如果参数值大于代码结尾，并且小于（堆栈-16kb），则设置新数据段结尾值
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if (end_data_seg >= current->end_code &&
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end_data_seg < current->start_stack - 16384)
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current->brk = end_data_seg;
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return current->brk;
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}
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/*
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* This needs some heave checking ...
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* I just haven't get the stomach for it. I also don't fully
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* understand sessions/pgrp etc. Let somebody who does explain it.
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*/
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int sys_setpgid(int pid, int pgid)
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{
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int i;
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if (!pid)
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pid = current->pid;
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if (!pgid)
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pgid = current->pid;
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for (i=0 ; i<NR_TASKS ; i++)
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if (task[i] && task[i]->pid==pid) {
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if (task[i]->leader)
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return -EPERM;
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if (task[i]->session != current->session)
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return -EPERM;
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task[i]->pgrp = pgid;
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return 0;
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}
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return -ESRCH;
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}
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int sys_getpgrp(void)
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{
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return current->pgrp;
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}
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int sys_setsid(void)
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{
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if (current->leader && !suser())
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return -EPERM;
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current->leader = 1;
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current->session = current->pgrp = current->pid;
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current->tty = -1;
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return current->pgrp;
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}
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int sys_getgroups()
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{
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return -ENOSYS;
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}
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int sys_setgroups()
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{
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return -ENOSYS;
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}
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int sys_uname(struct utsname * name)
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{
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static struct utsname thisname = {
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"linux .0","nodename","release ","version ","machine "
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};
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int i;
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if (!name) return -ERROR;
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verify_area(name,sizeof *name);
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for(i=0;i<sizeof *name;i++)
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put_fs_byte(((char *) &thisname)[i],i+(char *) name); //用来访问用户程序的数据
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return 0;
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}
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int sys_sethostname()
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{
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return -ENOSYS;
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}
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int sys_getrlimit()
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{
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return -ENOSYS;
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}
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int sys_setrlimit()
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{
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return -ENOSYS;
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}
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int sys_getrusage()
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{
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return -ENOSYS;
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}
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int sys_gettimeofday()
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{
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return -ENOSYS;
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}
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int sys_settimeofday()
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{
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return -ENOSYS;
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}
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int sys_umask(int mask)
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{
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int old = current->umask;
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current->umask = mask & 0777;
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return (old);
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}
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int sys_pipe2(void){
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return 0;
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}
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int sys_sleep(unsigned int seconds){
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sys_signal(SIGALRM,SIG_IGN);
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sys_alarm(seconds);
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sys_pause();
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return 0;
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}
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int sys_execve2(){
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return 0;
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}
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/*获取目录的目录项*/
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/*fd指目录描述符，dirp指目录信息，count指目录信息大小*/
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int sys_getdents(unsigned int fd,struct linux_dirent *dirp,unsigned int count)
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{
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struct file *file;
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struct m_inode *inode;
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struct buffer_head *bh;
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struct dir_entry *de;
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struct linux_dirent *temp;
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char * buf;
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int i,len = 0,ret = 0;
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if(!count)return -1;
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if(fd>=NR_OPEN)return -1; /*fd超过进程最多打开文件数20*/
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file=current->filp[fd];
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if(!file)return -1;
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inode = file->f_inode;
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temp = (struct linux_dirent *)malloc(sizeof(struct linux_dirent)); //目录信息
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buf = (char*)malloc(sizeof(struct linux_dirent));
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bh = bread(inode->i_dev , inode->i_zone[0]); //读取指向的数据块
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for (;ret<inode->i_size;ret += sizeof(struct dir_entry)){
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if (len >= count-sizeof(struct linux_dirent))
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break; /* full */
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de = (struct dir_entry *)(bh->b_data + ret);/*de更新为当前目录项*/
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if (!de->inode )/*如果节点号为空，就退出*/
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continue;
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/*用temp保存当前目录项信息*/
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temp->d_ino = de->inode;
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temp->d_off = 0;
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temp->d_reclen = sizeof(struct linux_dirent);
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strcpy(temp->d_name,de->name);
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/*将数据写回到用户*/
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memcpy(buf, temp, sizeof(struct linux_dirent));
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for (i=0;i < sizeof(struct linux_dirent);i++){
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put_fs_byte(*(buf+i), ((char*)dirp)+len+i); //用来访问用户程序的数据
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}
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len += sizeof(struct linux_dirent);
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}
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return len;
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}
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//参考find_entry
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int sys_getcwd(char* buf,size_t size){
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struct buffer_head *bh;
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struct dir_entry*de,*p_de;
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unsigned current_depth = 0;
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struct m_inode* current_ino;
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struct m_inode* parent_ino;
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char* t_buf;
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int ret = 0;
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t_buf = (char*)malloc(256);
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strcpy(t_buf,"");
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buf = malloc(size);
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if(!buf)return -1;
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for(;;){
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current_ino = namei(".");
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parent_ino = namei("..");
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if(current_ino == parent_ino) //找到了根节点
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break;
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sys_chdir("..");
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//read_inode(current_ino); 这是个静态函数
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//buf[current_depth++] = read_inode(current_ino);//根据节点号，在当前目录查找文件read_inode
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bh = bread(parent_ino->i_dev,parent_ino->i_zone[0]);
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for(;ret<parent_ino->i_size;ret+=sizeof(struct dir_entry))
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{
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de = (struct dir_entry*)(bh->b_data + ret);
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if(!de->inode)break;
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if(de->inode == (current_ino->i_num)){
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memcpy(t_buf,de->name,NAME_LEN);
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current_depth += NAME_LEN;
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break;
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}
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}
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//current_depth++;
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}
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// int i = current_depth-1;
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// for(i;i >= 0;i--){
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// printk("/%s",buf[i]);
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// }
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// printk("%s\n",current_depth==0?"/":"");
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// //复制过来
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int i;
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for(i = 0;t_buf[i];i++){
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put_fs_byte(t_buf[i],buf+i);
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}
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return (int)buf;
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}
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