kernel/sys.c

/* */
This source file includes following definitions.
proc_sel
sys_setpriority
sys_getpriority
sys_profil
sys_ftime
sys_break
sys_stty
sys_gtty
sys_prof
save_v86_state
mark_screen_rdonly
sys_vm86
sys_reboot
ctrl_alt_del
sys_setregid
sys_setgid
sys_acct
sys_phys
sys_lock
sys_mpx
sys_ulimit
sys_time
sys_setreuid
sys_setuid
sys_stime
sys_times
sys_brk
sys_setpgid
sys_getpgrp
sys_setsid
sys_getgroups
sys_setgroups
in_group_p
sys_newuname
sys_uname
sys_sethostname
sys_getrlimit
sys_setrlimit
getrusage
sys_getrusage
sys_gettimeofday
sys_settimeofday
adjust_clock
sys_umask
   1 /*
   2  *  linux/kernel/sys.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 #include <linux/errno.h>
   8 #include <linux/sched.h>
   9 #include <linux/tty.h>
  10 #include <linux/kernel.h>
  11 #include <linux/config.h>
  12 #include <linux/times.h>
  13 #include <linux/utsname.h>
  14 #include <linux/param.h>
  15 #include <linux/resource.h>
  16 #include <linux/signal.h>
  17 #include <linux/string.h>
  18 #include <linux/ptrace.h>
  19 
  20 #include <asm/segment.h>
  21 
  22 /*
  23  * this indicates wether you can reboot with ctrl-alt-del: the default is yes
  24  */
  25 static int C_A_D = 1;
  26 
  27 /* 
  28  * The timezone where the local system is located.  Used as a default by some
  29  * programs who obtain this value by using gettimeofday.
  30  */
  31 struct timezone sys_tz = { 0, 0};
  32 
  33 extern int session_of_pgrp(int pgrp);
  34 
  35 #define PZERO   15
  36 
  37 static int proc_sel(struct task_struct *p, int which, int who)
     /*  */
  38 {
  39         switch (which) {
  40                 case PRIO_PROCESS:
  41                         if (!who && p == current)
  42                                 return 1;
  43                         return(p->pid == who);
  44                 case PRIO_PGRP:
  45                         if (!who)
  46                                 who = current->pgrp;
  47                         return(p->pgrp == who);
  48                 case PRIO_USER:
  49                         if (!who)
  50                                 who = current->uid;
  51                         return(p->uid == who);
  52         }
  53         return 0;
  54 }
  55 
  56 int sys_setpriority(int which, int who, int niceval)
     /*  */
  57 {
  58         struct task_struct **p;
  59         int error = ESRCH;
  60         int priority;
  61 
  62         if (which > 2 || which < 0)
  63                 return -EINVAL;
  64 
  65         if ((priority = PZERO - niceval) <= 0)
  66                 priority = 1;
  67 
  68         for(p = &LAST_TASK; p > &FIRST_TASK; --p) {
  69                 if (!*p || !proc_sel(*p, which, who))
  70                         continue;
  71                 if ((*p)->uid != current->euid &&
  72                         (*p)->uid != current->uid && !suser()) {
  73                         error = EPERM;
  74                         continue;
  75                 }
  76                 if (error == ESRCH)
  77                         error = 0;
  78                 if (priority > (*p)->priority && !suser())
  79                         error = EACCES;
  80                 else
  81                         (*p)->priority = priority;
  82         }
  83         return -error;
  84 }
  85 
  86 int sys_getpriority(int which, int who)
     /*  */
  87 {
  88         struct task_struct **p;
  89         int max_prio = 0;
  90 
  91         if (which > 2 || which < 0)
  92                 return -EINVAL;
  93 
  94         for(p = &LAST_TASK; p > &FIRST_TASK; --p) {
  95                 if (!*p || !proc_sel(*p, which, who))
  96                         continue;
  97                 if ((*p)->priority > max_prio)
  98                         max_prio = (*p)->priority;
  99         }
 100         return(max_prio ? max_prio : -ESRCH);
 101 }
 102 
 103 int sys_profil()
     /*  */
 104 {
 105         return -ENOSYS;
 106 }
 107 
 108 int sys_ftime()
     /*  */
 109 {
 110         return -ENOSYS;
 111 }
 112 
 113 int sys_break()
     /*  */
 114 {
 115         return -ENOSYS;
 116 }
 117 
 118 int sys_stty()
     /*  */
 119 {
 120         return -ENOSYS;
 121 }
 122 
 123 int sys_gtty()
     /*  */
 124 {
 125         return -ENOSYS;
 126 }
 127 
 128 int sys_prof()
     /*  */
 129 {
 130         return -ENOSYS;
 131 }
 132 
 133 unsigned long save_v86_state(int signr,struct vm86_regs * regs)
     /*  */
 134 {
 135         unsigned long stack;
 136 
 137         if (!current->vm86_info) {
 138                 printk("no vm86_info: BAD\n");
 139                 do_exit(SIGSEGV);
 140         }
 141         memcpy_tofs(&(current->vm86_info->regs),regs,sizeof(*regs));
 142         put_fs_long(current->screen_bitmap,&(current->vm86_info->screen_bitmap));
 143         stack = current->tss.esp0;
 144         current->tss.esp0 = current->saved_kernel_stack;
 145         current->saved_kernel_stack = 0;
 146         return stack;
 147 }
 148 
 149 static void mark_screen_rdonly(struct task_struct * tsk)
     /*  */
 150 {
 151         unsigned long tmp;
 152         unsigned long *pg_table;
 153 
 154         if (tmp = tsk->tss.cr3) {
 155                 tmp = *(unsigned long *) tmp;
 156                 if (tmp & PAGE_PRESENT) {
 157                         tmp &= 0xfffff000;
 158                         pg_table = (0xA0000 >> PAGE_SHIFT) + (unsigned long *) tmp;
 159                         tmp = 32;
 160                         while (tmp--) {
 161                                 if (PAGE_PRESENT & *pg_table)
 162                                         *pg_table &= ~PAGE_RW;
 163                                 pg_table++;
 164                         }
 165                 }
 166         }
 167 }
 168 
 169 int sys_vm86(struct vm86_struct * v86)
     /*  */
 170 {
 171         struct vm86_struct info;
 172         struct pt_regs * pt_regs = (struct pt_regs *) &v86;
 173 
 174         if (current->saved_kernel_stack)
 175                 return -EPERM;
 176         memcpy_fromfs(&info,v86,sizeof(info));
 177 /*
 178  * make sure the vm86() system call doesn't try to do anything silly
 179  */
 180         info.regs.__null_ds = 0;
 181         info.regs.__null_es = 0;
 182         info.regs.__null_fs = 0;
 183         info.regs.__null_gs = 0;
 184 /*
 185  * The eflags register is also special: we cannot trust that the user
 186  * has set it up safely, so this makes sure interrupt etc flags are
 187  * inherited from protected mode.
 188  */
 189         info.regs.eflags &= 0x00000dd5;
 190         info.regs.eflags |= 0xfffff22a & pt_regs->eflags;
 191         info.regs.eflags |= VM_MASK;
 192         current->saved_kernel_stack = current->tss.esp0;
 193         current->tss.esp0 = (unsigned long) pt_regs;
 194         current->vm86_info = v86;
 195         current->screen_bitmap = info.screen_bitmap;
 196         if (info.flags & VM86_SCREEN_BITMAP)
 197                 mark_screen_rdonly(current);
 198         __asm__ __volatile__("movl %0,%%esp\n\t"
 199                 "pushl $ret_from_sys_call\n\t"
 200                 "ret"::"g" ((long) &(info.regs)),"a" (info.regs.eax));
 201         return 0;
 202 }
 203 
 204 extern void hard_reset_now(void);
 205 
 206 /*
 207  * Reboot system call: for obvious reasons only root may call it,
 208  * and even root needs to set up some magic numbers in the registers
 209  * so that some mistake won't make this reboot the whole machine.
 210  * You can also set the meaning of the ctrl-alt-del-key here.
 211  *
 212  * reboot doesn't sync: do that yourself before calling this.
 213  */
 214 int sys_reboot(int magic, int magic_too, int flag)
     /*  */
 215 {
 216         if (!suser())
 217                 return -EPERM;
 218         if (magic != 0xfee1dead || magic_too != 672274793)
 219                 return -EINVAL;
 220         if (flag == 0x01234567)
 221                 hard_reset_now();
 222         else if (flag == 0x89ABCDEF)
 223                 C_A_D = 1;
 224         else if (!flag)
 225                 C_A_D = 0;
 226         else
 227                 return -EINVAL;
 228         return (0);
 229 }
 230 
 231 /*
 232  * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
 233  * As it's called within an interrupt, it may NOT sync: the only choice
 234  * is wether to reboot at once, or just ignore the ctrl-alt-del.
 235  */
 236 void ctrl_alt_del(void)
     /*  */
 237 {
 238         if (C_A_D)
 239                 hard_reset_now();
 240         else
 241                 send_sig(SIGINT,task[1],1);
 242 }
 243         
 244 
 245 /*
 246  * This is done BSD-style, with no consideration of the saved gid, except
 247  * that if you set the effective gid, it sets the saved gid too.  This 
 248  * makes it possible for a setgid program to completely drop its privileges,
 249  * which is often a useful assertion to make when you are doing a security
 250  * audit over a program.
 251  *
 252  * The general idea is that a program which uses just setregid() will be
 253  * 100% compatible with BSD.  A program which uses just setgid() will be
 254  * 100% compatible with POSIX w/ Saved ID's. 
 255  */
 256 int sys_setregid(gid_t rgid, gid_t egid)
     /*  */
 257 {
 258         if (rgid != (gid_t) -1) {
 259                 if ((current->gid == rgid) || 
 260                     suser())
 261                         current->gid = rgid;
 262                 else
 263                         return(-EPERM);
 264         }
 265         if (egid != (gid_t) -1) {
 266                 if ((current->gid == egid) ||
 267                     (current->egid == egid) ||
 268                     suser()) {
 269                         current->egid = egid;
 270                         current->sgid = egid;
 271                 } else
 272                         return(-EPERM);
 273         }
 274         return 0;
 275 }
 276 
 277 /*
 278  * setgid() is implemeneted like SysV w/ SAVED_IDS 
 279  */
 280 int sys_setgid(gid_t gid)
     /*  */
 281 {
 282         if (suser())
 283                 current->gid = current->egid = current->sgid = gid;
 284         else if ((gid == current->gid) || (gid == current->sgid))
 285                 current->egid = gid;
 286         else
 287                 return -EPERM;
 288         return 0;
 289 }
 290 
 291 int sys_acct()
     /*  */
 292 {
 293         return -ENOSYS;
 294 }
 295 
 296 int sys_phys()
     /*  */
 297 {
 298         return -ENOSYS;
 299 }
 300 
 301 int sys_lock()
     /*  */
 302 {
 303         return -ENOSYS;
 304 }
 305 
 306 int sys_mpx()
     /*  */
 307 {
 308         return -ENOSYS;
 309 }
 310 
 311 int sys_ulimit()
     /*  */
 312 {
 313         return -ENOSYS;
 314 }
 315 
 316 int sys_time(long * tloc)
     /*  */
 317 {
 318         int i;
 319 
 320         i = CURRENT_TIME;
 321         if (tloc) {
 322                 verify_area(tloc,4);
 323                 put_fs_long(i,(unsigned long *)tloc);
 324         }
 325         return i;
 326 }
 327 
 328 /*
 329  * Unprivileged users may change the real user id to the effective uid
 330  * or vice versa.  (BSD-style)
 331  *
 332  * When you set the effective uid, it sets the saved uid too.  This 
 333  * makes it possible for a setuid program to completely drop its privileges,
 334  * which is often a useful assertion to make when you are doing a security
 335  * audit over a program.
 336  *
 337  * The general idea is that a program which uses just setreuid() will be
 338  * 100% compatible with BSD.  A program which uses just setuid() will be
 339  * 100% compatible with POSIX w/ Saved ID's. 
 340  */
 341 int sys_setreuid(uid_t ruid, uid_t euid)
     /*  */
 342 {
 343         int old_ruid = current->uid;
 344         
 345         if (ruid != (uid_t) -1) {
 346                 if ((current->euid==ruid) ||
 347                     (old_ruid == ruid) ||
 348                     suser())
 349                         current->uid = ruid;
 350                 else
 351                         return(-EPERM);
 352         }
 353         if (euid != (uid_t) -1) {
 354                 if ((old_ruid == euid) ||
 355                     (current->euid == euid) ||
 356                     suser()) {
 357                         current->euid = euid;
 358                         current->suid = euid;
 359                 } else {
 360                         current->uid = old_ruid;
 361                         return(-EPERM);
 362                 }
 363         }
 364         return 0;
 365 }
 366 
 367 /*
 368  * setuid() is implemeneted like SysV w/ SAVED_IDS 
 369  * 
 370  * Note that SAVED_ID's is deficient in that a setuid root program
 371  * like sendmail, for example, cannot set its uid to be a normal 
 372  * user and then switch back, because if you're root, setuid() sets
 373  * the saved uid too.  If you don't like this, blame the bright people
 374  * in the POSIX commmittee and/or USG.  Note that the BSD-style setreuid()
 375  * will allow a root program to temporarily drop privileges and be able to
 376  * regain them by swapping the real and effective uid.  
 377  */
 378 int sys_setuid(uid_t uid)
     /*  */
 379 {
 380         if (suser())
 381                 current->uid = current->euid = current->suid = uid;
 382         else if ((uid == current->uid) || (uid == current->suid))
 383                 current->euid = uid;
 384         else
 385                 return -EPERM;
 386         return(0);
 387 }
 388 
 389 int sys_stime(long * tptr)
     /*  */
 390 {
 391         if (!suser())
 392                 return -EPERM;
 393         startup_time = get_fs_long((unsigned long *)tptr) - jiffies/HZ;
 394         jiffies_offset = 0;
 395         return 0;
 396 }
 397 
 398 int sys_times(struct tms * tbuf)
     /*  */
 399 {
 400         if (tbuf) {
 401                 verify_area(tbuf,sizeof *tbuf);
 402                 put_fs_long(current->utime,(unsigned long *)&tbuf->tms_utime);
 403                 put_fs_long(current->stime,(unsigned long *)&tbuf->tms_stime);
 404                 put_fs_long(current->cutime,(unsigned long *)&tbuf->tms_cutime);
 405                 put_fs_long(current->cstime,(unsigned long *)&tbuf->tms_cstime);
 406         }
 407         return jiffies;
 408 }
 409 
 410 int sys_brk(unsigned long end_data_seg)
     /*  */
 411 {
 412         if (end_data_seg >= current->end_code &&
 413             end_data_seg < current->start_stack - 16384)
 414                 current->brk = end_data_seg;
 415         return current->brk;
 416 }
 417 
 418 /*
 419  * This needs some heave checking ...
 420  * I just haven't get the stomach for it. I also don't fully
 421  * understand sessions/pgrp etc. Let somebody who does explain it.
 422  *
 423  * OK, I think I have the protection semantics right.... this is really
 424  * only important on a multi-user system anyway, to make sure one user
 425  * can't send a signal to a process owned by another.  -TYT, 12/12/91
 426  */
 427 int sys_setpgid(pid_t pid, pid_t pgid)
     /*  */
 428 {
 429         int i; 
 430 
 431         if (!pid)
 432                 pid = current->pid;
 433         if (!pgid)
 434                 pgid = current->pid;
 435         if (pgid < 0)
 436                 return -EINVAL;
 437         for (i=0 ; i<NR_TASKS ; i++)
 438                 if (task[i] && (task[i]->pid == pid) &&
 439                     ((task[i]->p_pptr == current) || 
 440                      (task[i] == current))) {
 441                         if (task[i]->leader)
 442                                 return -EPERM;
 443                         if ((task[i]->session != current->session) ||
 444                             ((pgid != pid) && 
 445                              (session_of_pgrp(pgid) != current->session)))
 446                                 return -EPERM;
 447                         task[i]->pgrp = pgid;
 448                         return 0;
 449                 }
 450         return -ESRCH;
 451 }
 452 
 453 int sys_getpgrp(void)
     /*  */
 454 {
 455         return current->pgrp;
 456 }
 457 
 458 int sys_setsid(void)
     /*  */
 459 {
 460         if (current->leader && !suser())
 461                 return -EPERM;
 462         current->leader = 1;
 463         current->session = current->pgrp = current->pid;
 464         current->tty = -1;
 465         return current->pgrp;
 466 }
 467 
 468 /*
 469  * Supplementary group ID's
 470  */
 471 int sys_getgroups(int gidsetsize, gid_t *grouplist)
     /*  */
 472 {
 473         int     i;
 474 
 475         if (gidsetsize)
 476                 verify_area(grouplist, sizeof(gid_t) * gidsetsize);
 477 
 478         for (i = 0; (i < NGROUPS) && (current->groups[i] != NOGROUP);
 479              i++, grouplist++) {
 480                 if (gidsetsize) {
 481                         if (i >= gidsetsize)
 482                                 return -EINVAL;
 483                         put_fs_word(current->groups[i], (short *) grouplist);
 484                 }
 485         }
 486         return(i);
 487 }
 488 
 489 int sys_setgroups(int gidsetsize, gid_t *grouplist)
     /*  */
 490 {
 491         int     i;
 492 
 493         if (!suser())
 494                 return -EPERM;
 495         if (gidsetsize > NGROUPS)
 496                 return -EINVAL;
 497         for (i = 0; i < gidsetsize; i++, grouplist++) {
 498                 current->groups[i] = get_fs_word((unsigned short *) grouplist);
 499         }
 500         if (i < NGROUPS)
 501                 current->groups[i] = NOGROUP;
 502         return 0;
 503 }
 504 
 505 int in_group_p(gid_t grp)
     /*  */
 506 {
 507         int     i;
 508 
 509         if (grp == current->egid)
 510                 return 1;
 511 
 512         for (i = 0; i < NGROUPS; i++) {
 513                 if (current->groups[i] == NOGROUP)
 514                         break;
 515                 if (current->groups[i] == grp)
 516                         return 1;
 517         }
 518         return 0;
 519 }
 520 
 521 int sys_newuname(struct new_utsname * name)
     /*  */
 522 {
 523         if (!name)
 524                 return -EFAULT;
 525         verify_area(name, sizeof *name);
 526         memcpy_tofs(name,&system_utsname,sizeof *name);
 527         return 0;
 528 }
 529 
 530 int sys_uname(struct old_utsname * name)
     /*  */
 531 {
 532         if (!name)
 533                 return -EINVAL;
 534         verify_area(name,sizeof *name);
 535         memcpy_tofs(&name->sysname,&system_utsname.sysname,__OLD_UTS_LEN);
 536         put_fs_byte(0,name->sysname+__OLD_UTS_LEN);
 537         memcpy_tofs(&name->nodename,&system_utsname.nodename,__OLD_UTS_LEN);
 538         put_fs_byte(0,name->nodename+__OLD_UTS_LEN);
 539         memcpy_tofs(&name->release,&system_utsname.release,__OLD_UTS_LEN);
 540         put_fs_byte(0,name->release+__OLD_UTS_LEN);
 541         memcpy_tofs(&name->version,&system_utsname.version,__OLD_UTS_LEN);
 542         put_fs_byte(0,name->version+__OLD_UTS_LEN);
 543         memcpy_tofs(&name->machine,&system_utsname.machine,__OLD_UTS_LEN);
 544         put_fs_byte(0,name->machine+__OLD_UTS_LEN);
 545         return 0;
 546 }
 547 
 548 /*
 549  * Only sethostname; gethostname can be implemented by calling uname()
 550  */
 551 int sys_sethostname(char *name, int len)
     /*  */
 552 {
 553         int     i;
 554         
 555         if (!suser())
 556                 return -EPERM;
 557         if (len > __NEW_UTS_LEN)
 558                 return -EINVAL;
 559         for (i=0; i < len; i++) {
 560                 if ((system_utsname.nodename[i] = get_fs_byte(name+i)) == 0)
 561                         return 0;
 562         }
 563         system_utsname.nodename[i] = 0;
 564         return 0;
 565 }
 566 
 567 int sys_getrlimit(unsigned int resource, struct rlimit *rlim)
     /*  */
 568 {
 569         if (resource >= RLIM_NLIMITS)
 570                 return -EINVAL;
 571         verify_area(rlim,sizeof *rlim);
 572         put_fs_long(current->rlim[resource].rlim_cur, 
 573                     (unsigned long *) rlim);
 574         put_fs_long(current->rlim[resource].rlim_max, 
 575                     ((unsigned long *) rlim)+1);
 576         return 0;       
 577 }
 578 
 579 int sys_setrlimit(unsigned int resource, struct rlimit *rlim)
     /*  */
 580 {
 581         struct rlimit new, *old;
 582 
 583         if (resource >= RLIM_NLIMITS)
 584                 return -EINVAL;
 585         old = current->rlim + resource;
 586         new.rlim_cur = get_fs_long((unsigned long *) rlim);
 587         new.rlim_max = get_fs_long(((unsigned long *) rlim)+1);
 588         if (((new.rlim_cur > old->rlim_max) ||
 589              (new.rlim_max > old->rlim_max)) &&
 590             !suser())
 591                 return -EPERM;
 592         *old = new;
 593         return 0;
 594 }
 595 
 596 /*
 597  * It would make sense to put struct rusuage in the task_struct,
 598  * except that would make the task_struct be *really big*.  After
 599  * task_struct gets moved into malloc'ed memory, it would
 600  * make sense to do this.  It will make moving the rest of the information
 601  * a lot simpler!  (Which we're not doing right now because we're not
 602  * measuring them yet).
 603  */
 604 void getrusage(struct task_struct *p, int who, struct rusage *ru)
     /*  */
 605 {
 606         struct rusage r;
 607         unsigned long   *lp, *lpend, *dest;
 608 
 609         verify_area(ru, sizeof *ru);
 610         memset((char *) &r, 0, sizeof(r));
 611         switch (who) {
 612                 case RUSAGE_SELF:
 613                         r.ru_utime.tv_sec = CT_TO_SECS(p->utime);
 614                         r.ru_utime.tv_usec = CT_TO_USECS(p->utime);
 615                         r.ru_stime.tv_sec = CT_TO_SECS(p->stime);
 616                         r.ru_stime.tv_usec = CT_TO_USECS(p->stime);
 617                         r.ru_minflt = p->min_flt;
 618                         r.ru_majflt = p->maj_flt;
 619                         break;
 620                 case RUSAGE_CHILDREN:
 621                         r.ru_utime.tv_sec = CT_TO_SECS(p->cutime);
 622                         r.ru_utime.tv_usec = CT_TO_USECS(p->cutime);
 623                         r.ru_stime.tv_sec = CT_TO_SECS(p->cstime);
 624                         r.ru_stime.tv_usec = CT_TO_USECS(p->cstime);
 625                         r.ru_minflt = p->cmin_flt;
 626                         r.ru_majflt = p->cmaj_flt;
 627                         break;
 628                 default:
 629                         r.ru_utime.tv_sec = CT_TO_SECS(p->utime + p->cutime);
 630                         r.ru_utime.tv_usec = CT_TO_USECS(p->utime + p->cutime);
 631                         r.ru_stime.tv_sec = CT_TO_SECS(p->stime + p->cstime);
 632                         r.ru_stime.tv_usec = CT_TO_USECS(p->stime + p->cstime);
 633                         r.ru_minflt = p->min_flt + p->cmin_flt;
 634                         r.ru_majflt = p->maj_flt + p->cmaj_flt;
 635                         break;
 636         }
 637         lp = (unsigned long *) &r;
 638         lpend = (unsigned long *) (&r+1);
 639         dest = (unsigned long *) ru;
 640         for (; lp < lpend; lp++, dest++) 
 641                 put_fs_long(*lp, dest);
 642 }
 643 
 644 int sys_getrusage(int who, struct rusage *ru)
     /*  */
 645 {
 646         if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN)
 647                 return -EINVAL;
 648         getrusage(current, who, ru);
 649         return(0);
 650 }
 651 
 652 int sys_gettimeofday(struct timeval *tv, struct timezone *tz)
     /*  */
 653 {
 654         if (tv) {
 655                 verify_area(tv, sizeof *tv);
 656                 put_fs_long(startup_time + CT_TO_SECS(jiffies+jiffies_offset),
 657                             (unsigned long *) tv);
 658                 put_fs_long(CT_TO_USECS(jiffies+jiffies_offset), 
 659                             ((unsigned long *) tv)+1);
 660         }
 661         if (tz) {
 662                 verify_area(tz, sizeof *tz);
 663                 put_fs_long(sys_tz.tz_minuteswest, (unsigned long *) tz);
 664                 put_fs_long(sys_tz.tz_dsttime, ((unsigned long *) tz)+1);
 665         }
 666         return 0;
 667 }
 668 
 669 /*
 670  * The first time we set the timezone, we will warp the clock so that
 671  * it is ticking GMT time instead of local time.  Presumably, 
 672  * if someone is setting the timezone then we are running in an
 673  * environment where the programs understand about timezones.
 674  * This should be done at boot time in the /etc/rc script, as
 675  * soon as possible, so that the clock can be set right.  Otherwise,
 676  * various programs will get confused when the clock gets warped.
 677  */
 678 int sys_settimeofday(struct timeval *tv, struct timezone *tz)
     /*  */
 679 {
 680         static int      firsttime = 1;
 681         void            adjust_clock();
 682 
 683         if (!suser())
 684                 return -EPERM;
 685         if (tz) {
 686                 sys_tz.tz_minuteswest = get_fs_long((unsigned long *) tz);
 687                 sys_tz.tz_dsttime = get_fs_long(((unsigned long *) tz)+1);
 688                 if (firsttime) {
 689                         firsttime = 0;
 690                         if (!tv)
 691                                 adjust_clock();
 692                 }
 693         }
 694         if (tv) {
 695                 int sec, usec;
 696 
 697                 sec = get_fs_long((unsigned long *)tv);
 698                 usec = get_fs_long(((unsigned long *)tv)+1);
 699         
 700                 startup_time = sec - jiffies/HZ;
 701                 jiffies_offset = usec * HZ / 1000000 - jiffies%HZ;
 702         }
 703         return 0;
 704 }
 705 
 706 /*
 707  * Adjust the time obtained from the CMOS to be GMT time instead of
 708  * local time.
 709  * 
 710  * This is ugly, but preferable to the alternatives.  Otherwise we
 711  * would either need to write a program to do it in /etc/rc (and risk
 712  * confusion if the program gets run more than once; it would also be 
 713  * hard to make the program warp the clock precisely n hours)  or
 714  * compile in the timezone information into the kernel.  Bad, bad....
 715  *
 716  * XXX Currently does not adjust for daylight savings time.  May not
 717  * need to do anything, depending on how smart (dumb?) the BIOS
 718  * is.  Blast it all.... the best thing to do not depend on the CMOS
 719  * clock at all, but get the time via NTP or timed if you're on a 
 720  * network....                          - TYT, 1/1/92
 721  */
 722 void adjust_clock()
     /*  */
 723 {
 724         startup_time += sys_tz.tz_minuteswest*60;
 725 }
 726 
 727 int sys_umask(int mask)
     /*  */
 728 {
 729         int old = current->umask;
 730 
 731         current->umask = mask & 0777;
 732         return (old);
 733 }
 734
/* */
root/kernel/sys.c

DEFINITIONS
