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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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#define __LIBRARY__
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#include <linux/sched.h>
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#include <linux/tty.h>
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#include <linux/kernel.h>
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#include <asm/segment.h>
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#include <sys/times.h>
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#include <sys/utsname.h>
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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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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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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);
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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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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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int sys_brk(unsigned long end_data_seg)
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{
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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);
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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(int * pipefd,int flags)
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{
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sys_pipe(pipefd);
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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);//收到SIGALRM信号，则忽略，啥也不干
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sys_alarm(seconds);//设定一个时长为seconds秒的闹钟
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/*
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系统调用pause函数，来暂停当前进程，当前进程进入睡眠状态。
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直到接收到信号且信号函数成功返回，pause函数才会返回，而且返回值为-1。
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*/
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sys_pause();
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return 0;
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}
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#define NAME_MAX 255
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struct linux_dirent { //专为输出的目录项结构
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long d_ino;
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off_t d_off;
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unsigned short d_reclen;
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char d_name[NAME_MAX+1];
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};
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int sys_getdents(unsigned int fd, struct dirent *dirp, unsigned int count)
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{
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//初始化
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struct file *file; //文件结构
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struct m_inode *inode; //索引节点结构inode
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struct buffer_head *bufhd; //缓冲块头结构
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struct dir_entry *d_entry; //目录项结构(内存)
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int linux_dirent_size = sizeof(struct linux_dirent);
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int dir_entry_size = sizeof(struct dir_entry);
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int l = 0;//l为已读linux_dirent总字节数
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int d = 0;//d为已读页表项的总字节数
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int i;
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//检查参数合法性
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if(fd >= NR_OPEN) return -1; //目录的文件描述符错误
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if(count < linux_dirent_size) return -1;//写入的字节数不足一个linux_dirent
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file = current->filp[fd];
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if(!file) return -1; //没读到目录文件
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//读目录
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inode = file->f_inode; //目录的索引节点
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struct linux_dirent *dirp_tmp; //专为输出的目录项结构,为dirp的赋值而开
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dirp_tmp = (struct dirent *)malloc(linux_dirent_size);
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char * buf; //为dirp的赋值而开，大小为一个linux_dirent
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buf = (char*)malloc(linux_dirent_size);
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bufhd = bread(inode->i_dev , inode->i_zone[0]);//读出目录索引节点中的第一个数据块的内容
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for( ; d < inode->i_size ; d += dir_entry_size)
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{
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if(l >= count - linux_dirent_size) return l;//dirp已经满了，返回读取的字节数
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//bufhd->b_data 是char*类型的指针(char为一字节)，因此+d可以到这个目录项
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d_entry = (struct dir_entry *)(bufhd->b_data + d);
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//读到了目录的最后一项，则返回0
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if(!d_entry->inode) return 0;
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//将目录项信息从dir_entry转移到dirp_tmp //d_entry(dir_entry)----->dirp_tmp(linux_dirent)
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dirp_tmp->d_ino = d_entry->inode;
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dirp_tmp->d_off = 0;
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dirp_tmp->d_reclen = linux_dirent_size;
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strcpy(dirp_tmp->d_name,dir_entry->name);
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//将dirp_tmp的信息转化成char类型并存到buf //dirp_tmp(linux_dirent)--->buf(char)
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memcpy(buf,dirp_tmp,linux_dirent_size);
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//利用put_fs_byte将buf(在核心数据段)逐字节存入dirp(在用户数据段，段基址在fs，即fs:[addr])
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for(i=0 ; i < linux_dirent_size ; i++){ //buf(char)--->dirp数组(linux_dirent)
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put_fs_byte(*(buf+i), ((char*)dirp)+i+l);
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}
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l += linux_dirent_size;
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}
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}
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char * sys_getcwd(char * buf, size_t size){
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}
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int sys_execve2(){};
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long sys_mmap(void *start, size_t len, int prot, int flags,
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int fd, off_t off){}
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int sys_munmap(void * start, size_t len){}
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int sys_clone(int (*fn)(void *), void *child_stack, int flags, void *arg){}
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