The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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sys/kern/kern_acct.c

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    1 /*      $NetBSD: kern_acct.c,v 1.56 2004/03/23 13:22:03 junyoung Exp $  */
    2 
    3 /*-
    4  * Copyright (c) 1982, 1986, 1989, 1993
    5  *      The Regents of the University of California.  All rights reserved.
    6  * (c) UNIX System Laboratories, Inc.
    7  * All or some portions of this file are derived from material licensed
    8  * to the University of California by American Telephone and Telegraph
    9  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   10  * the permission of UNIX System Laboratories, Inc.
   11  *
   12  * Redistribution and use in source and binary forms, with or without
   13  * modification, are permitted provided that the following conditions
   14  * are met:
   15  * 1. Redistributions of source code must retain the above copyright
   16  *    notice, this list of conditions and the following disclaimer.
   17  * 2. Redistributions in binary form must reproduce the above copyright
   18  *    notice, this list of conditions and the following disclaimer in the
   19  *    documentation and/or other materials provided with the distribution.
   20  * 3. Neither the name of the University nor the names of its contributors
   21  *    may be used to endorse or promote products derived from this software
   22  *    without specific prior written permission.
   23  *
   24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   34  * SUCH DAMAGE.
   35  *
   36  *      @(#)kern_acct.c 8.8 (Berkeley) 5/14/95
   37  */
   38 
   39 /*-
   40  * Copyright (c) 1994 Christopher G. Demetriou
   41  *
   42  * Redistribution and use in source and binary forms, with or without
   43  * modification, are permitted provided that the following conditions
   44  * are met:
   45  * 1. Redistributions of source code must retain the above copyright
   46  *    notice, this list of conditions and the following disclaimer.
   47  * 2. Redistributions in binary form must reproduce the above copyright
   48  *    notice, this list of conditions and the following disclaimer in the
   49  *    documentation and/or other materials provided with the distribution.
   50  * 3. All advertising materials mentioning features or use of this software
   51  *    must display the following acknowledgement:
   52  *      This product includes software developed by the University of
   53  *      California, Berkeley and its contributors.
   54  * 4. Neither the name of the University nor the names of its contributors
   55  *    may be used to endorse or promote products derived from this software
   56  *    without specific prior written permission.
   57  *
   58  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   59  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   60  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   61  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   62  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   63  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   64  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   65  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   66  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   67  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   68  * SUCH DAMAGE.
   69  *
   70  *      @(#)kern_acct.c 8.8 (Berkeley) 5/14/95
   71  */
   72 
   73 #include <sys/cdefs.h>
   74 __KERNEL_RCSID(0, "$NetBSD: kern_acct.c,v 1.56 2004/03/23 13:22:03 junyoung Exp $");
   75 
   76 #include <sys/param.h>
   77 #include <sys/systm.h>
   78 #include <sys/proc.h>
   79 #include <sys/mount.h>
   80 #include <sys/vnode.h>
   81 #include <sys/file.h>
   82 #include <sys/syslog.h>
   83 #include <sys/kernel.h>
   84 #include <sys/kthread.h>
   85 #include <sys/lock.h>
   86 #include <sys/malloc.h>
   87 #include <sys/namei.h>
   88 #include <sys/errno.h>
   89 #include <sys/acct.h>
   90 #include <sys/resourcevar.h>
   91 #include <sys/ioctl.h>
   92 #include <sys/tty.h>
   93 
   94 #include <sys/sa.h>
   95 #include <sys/syscallargs.h>
   96 
   97 /*
   98  * The routines implemented in this file are described in:
   99  *      Leffler, et al.: The Design and Implementation of the 4.3BSD
  100  *          UNIX Operating System (Addison Welley, 1989)
  101  * on pages 62-63.
  102  *
  103  * Arguably, to simplify accounting operations, this mechanism should
  104  * be replaced by one in which an accounting log file (similar to /dev/klog)
  105  * is read by a user process, etc.  However, that has its own problems.
  106  */
  107 
  108 /*
  109  * The global accounting state and related data.  Gain the lock before
  110  * accessing these variables.
  111  */
  112 enum {
  113         ACCT_STOP,
  114         ACCT_ACTIVE,
  115         ACCT_SUSPENDED
  116 } acct_state;                           /* The current accounting state. */
  117 struct vnode *acct_vp;                  /* Accounting vnode pointer. */
  118 struct ucred *acct_ucred;               /* Credential of accounting file
  119                                            owner (i.e root).  Used when
  120                                            accounting file i/o.  */
  121 struct proc *acct_dkwatcher;            /* Free disk space checker. */
  122 
  123 /*
  124  * Lock to serialize system calls and kernel threads.
  125  */
  126 struct  lock acct_lock;
  127 #define ACCT_LOCK()                                             \
  128 do {                                                            \
  129         (void) lockmgr(&acct_lock, LK_EXCLUSIVE, NULL);         \
  130 } while (/* CONSTCOND */0)
  131 #define ACCT_UNLOCK()                                           \
  132 do {                                                            \
  133         (void) lockmgr(&acct_lock, LK_RELEASE, NULL);           \
  134 } while (/* CONSTCOND */0)
  135 
  136 /*
  137  * Internal accounting functions.
  138  * The former's operation is described in Leffler, et al., and the latter
  139  * was provided by UCB with the 4.4BSD-Lite release
  140  */
  141 comp_t  encode_comp_t(u_long, u_long);
  142 void    acctwatch(void *);
  143 void    acct_stop(void);
  144 int     acct_chkfree(void);
  145 
  146 /*
  147  * Values associated with enabling and disabling accounting
  148  */
  149 int     acctsuspend = 2;        /* stop accounting when < 2% free space left */
  150 int     acctresume = 4;         /* resume when free space risen to > 4% */
  151 int     acctchkfreq = 15;       /* frequency (in seconds) to check space */
  152 
  153 void
  154 acct_init()
  155 {
  156 
  157         acct_state = ACCT_STOP;
  158         acct_vp = NULLVP;
  159         acct_ucred = NULL;
  160         lockinit(&acct_lock, PWAIT, "acctlk", 0, 0);
  161 }
  162 
  163 void
  164 acct_stop()
  165 {
  166         int error;
  167 
  168         if (acct_vp != NULLVP && acct_vp->v_type != VBAD) {
  169                 error = vn_close(acct_vp, FWRITE, acct_ucred, NULL);
  170 #ifdef DIAGNOSTIC
  171                 if (error != 0)
  172                         printf("acct_stop: failed to close, errno = %d\n",
  173                             error);
  174 #endif
  175                 acct_vp = NULLVP;
  176         }
  177         if (acct_ucred != NULL) {
  178                 crfree(acct_ucred);
  179                 acct_ucred = NULL;
  180         }
  181         acct_state = ACCT_STOP;
  182 }
  183 
  184 int
  185 acct_chkfree()
  186 {
  187         int error;
  188         struct statfs sb;
  189 
  190         error = VFS_STATFS(acct_vp->v_mount, &sb, NULL);
  191         if (error != 0)
  192                 return (error);
  193 
  194         switch (acct_state) {
  195         case ACCT_SUSPENDED:
  196                 if (sb.f_bavail > acctresume * sb.f_blocks / 100) {
  197                         acct_state = ACCT_ACTIVE;
  198                         log(LOG_NOTICE, "Accounting resumed\n");
  199                 }
  200                 break;
  201         case ACCT_ACTIVE:
  202                 if (sb.f_bavail <= acctsuspend * sb.f_blocks / 100) {
  203                         acct_state = ACCT_SUSPENDED;
  204                         log(LOG_NOTICE, "Accounting suspended\n");
  205                 }
  206                 break;
  207         case ACCT_STOP:
  208                 break;
  209         }
  210         return (0);
  211 }
  212 
  213 /*
  214  * Accounting system call.  Written based on the specification and
  215  * previous implementation done by Mark Tinguely.
  216  */
  217 int
  218 sys_acct(l, v, retval)
  219         struct lwp *l;
  220         void *v;
  221         register_t *retval;
  222 {
  223         struct sys_acct_args /* {
  224                 syscallarg(const char *) path;
  225         } */ *uap = v;
  226         struct nameidata nd;
  227         int error;
  228         struct proc *p = l->l_proc;
  229 
  230         /* Make sure that the caller is root. */
  231         if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
  232                 return (error);
  233 
  234         /*
  235          * If accounting is to be started to a file, open that file for
  236          * writing and make sure it's a 'normal'.
  237          */
  238         if (SCARG(uap, path) != NULL) {
  239                 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, SCARG(uap, path),
  240                     p);
  241                 if ((error = vn_open(&nd, FWRITE|O_APPEND, 0)) != 0)
  242                         return (error);
  243                 VOP_UNLOCK(nd.ni_vp, 0);
  244                 if (nd.ni_vp->v_type != VREG) {
  245                         vn_close(nd.ni_vp, FWRITE, p->p_ucred, p);
  246                         return (EACCES);
  247                 }
  248         }
  249 
  250         ACCT_LOCK();
  251 
  252         /*
  253          * If accounting was previously enabled, kill the old space-watcher,
  254          * free credential for accounting file i/o,
  255          * ... (and, if no new file was specified, leave).
  256          */
  257         acct_stop();
  258         if (SCARG(uap, path) == NULL)
  259                 goto out;
  260 
  261         /*
  262          * Save the new accounting file vnode and credential,
  263          * and schedule the new free space watcher.
  264          */
  265         acct_state = ACCT_ACTIVE;
  266         acct_vp = nd.ni_vp;
  267         acct_ucred = p->p_ucred;
  268         crhold(acct_ucred);
  269 
  270         error = acct_chkfree();         /* Initial guess. */
  271         if (error != 0) {
  272                 acct_stop();
  273                 goto out;
  274         }
  275 
  276         if (acct_dkwatcher == NULL) {
  277                 error = kthread_create1(acctwatch, NULL, &acct_dkwatcher,
  278                     "acctwatch");
  279                 if (error != 0)
  280                         acct_stop();
  281         }
  282 
  283  out:
  284         ACCT_UNLOCK();
  285         return (error);
  286 }
  287 
  288 /*
  289  * Write out process accounting information, on process exit.
  290  * Data to be written out is specified in Leffler, et al.
  291  * and are enumerated below.  (They're also noted in the system
  292  * "acct.h" header file.)
  293  */
  294 int
  295 acct_process(p)
  296         struct proc *p;
  297 {
  298         struct acct acct;
  299         struct rusage *r;
  300         struct timeval ut, st, tmp;
  301         int s, t, error = 0;
  302         struct plimit *oplim = NULL;
  303 
  304         ACCT_LOCK();
  305 
  306         /* If accounting isn't enabled, don't bother */
  307         if (acct_state != ACCT_ACTIVE)
  308                 goto out;
  309 
  310         /*
  311          * Raise the file limit so that accounting can't be stopped by
  312          * the user.
  313          *
  314          * XXX We should think about the CPU limit, too.
  315          */
  316         if (p->p_limit->p_refcnt > 1) {
  317                 oplim = p->p_limit;
  318                 p->p_limit = limcopy(p->p_limit);
  319         }
  320         p->p_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
  321 
  322         /*
  323          * Get process accounting information.
  324          */
  325 
  326         /* (1) The name of the command that ran */
  327         memcpy(acct.ac_comm, p->p_comm, sizeof(acct.ac_comm));
  328 
  329         /* (2) The amount of user and system time that was used */
  330         calcru(p, &ut, &st, NULL);
  331         acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_usec);
  332         acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_usec);
  333 
  334         /* (3) The elapsed time the commmand ran (and its starting time) */
  335         acct.ac_btime = p->p_stats->p_start.tv_sec;
  336         s = splclock();
  337         timersub(&time, &p->p_stats->p_start, &tmp);
  338         splx(s);
  339         acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);
  340 
  341         /* (4) The average amount of memory used */
  342         r = &p->p_stats->p_ru;
  343         timeradd(&ut, &st, &tmp);
  344         t = tmp.tv_sec * hz + tmp.tv_usec / tick;
  345         if (t)
  346                 acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
  347         else
  348                 acct.ac_mem = 0;
  349 
  350         /* (5) The number of disk I/O operations done */
  351         acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
  352 
  353         /* (6) The UID and GID of the process */
  354         acct.ac_uid = p->p_cred->p_ruid;
  355         acct.ac_gid = p->p_cred->p_rgid;
  356 
  357         /* (7) The terminal from which the process was started */
  358         if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
  359                 acct.ac_tty = p->p_pgrp->pg_session->s_ttyp->t_dev;
  360         else
  361                 acct.ac_tty = NODEV;
  362 
  363         /* (8) The boolean flags that tell how the process terminated, etc. */
  364         acct.ac_flag = p->p_acflag;
  365 
  366         /*
  367          * Now, just write the accounting information to the file.
  368          */
  369         VOP_LEASE(acct_vp, p, p->p_ucred, LEASE_WRITE);
  370         error = vn_rdwr(UIO_WRITE, acct_vp, (caddr_t)&acct,
  371             sizeof(acct), (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT,
  372             acct_ucred, NULL, p);
  373         if (error != 0)
  374                 log(LOG_ERR, "Accounting: write failed %d\n", error);
  375 
  376         if (oplim) {
  377                 limfree(p->p_limit);
  378                 p->p_limit = oplim;
  379         }
  380 
  381  out:
  382         ACCT_UNLOCK();
  383         return (error);
  384 }
  385 
  386 /*
  387  * Encode_comp_t converts from ticks in seconds and microseconds
  388  * to ticks in 1/AHZ seconds.  The encoding is described in
  389  * Leffler, et al., on page 63.
  390  */
  391 
  392 #define MANTSIZE        13                      /* 13 bit mantissa. */
  393 #define EXPSIZE         3                       /* Base 8 (3 bit) exponent. */
  394 #define MAXFRACT        ((1 << MANTSIZE) - 1)   /* Maximum fractional value. */
  395 
  396 comp_t
  397 encode_comp_t(s, us)
  398         u_long s, us;
  399 {
  400         int exp, rnd;
  401 
  402         exp = 0;
  403         rnd = 0;
  404         s *= AHZ;
  405         s += us / (1000000 / AHZ);      /* Maximize precision. */
  406 
  407         while (s > MAXFRACT) {
  408         rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
  409                 s >>= EXPSIZE;          /* Base 8 exponent == 3 bit shift. */
  410                 exp++;
  411         }
  412 
  413         /* If we need to round up, do it (and handle overflow correctly). */
  414         if (rnd && (++s > MAXFRACT)) {
  415                 s >>= EXPSIZE;
  416                 exp++;
  417         }
  418 
  419         /* Clean it up and polish it off. */
  420         exp <<= MANTSIZE;               /* Shift the exponent into place */
  421         exp += s;                       /* and add on the mantissa. */
  422         return (exp);
  423 }
  424 
  425 /*
  426  * Periodically check the file system to see if accounting
  427  * should be turned on or off.  Beware the case where the vnode
  428  * has been vgone()'d out from underneath us, e.g. when the file
  429  * system containing the accounting file has been forcibly unmounted.
  430  */
  431 void
  432 acctwatch(arg)
  433         void *arg;
  434 {
  435         int error;
  436 
  437         log(LOG_NOTICE, "Accounting started\n");
  438         ACCT_LOCK();
  439         while (acct_state != ACCT_STOP) {
  440                 if (acct_vp->v_type == VBAD) {
  441                         log(LOG_NOTICE, "Accounting terminated\n");
  442                         acct_stop();
  443                         continue;
  444                 }
  445 
  446                 error = acct_chkfree();
  447 #ifdef DIAGNOSTIC
  448                 if (error != 0)
  449                         printf("acctwatch: failed to statfs, error = %d\n",
  450                             error);
  451 #endif
  452 
  453                 ACCT_UNLOCK();
  454                 error = tsleep(acctwatch, PSWP, "actwat", acctchkfreq * hz);
  455                 ACCT_LOCK();
  456 #ifdef DIAGNOSTIC
  457                 if (error != 0 && error != EWOULDBLOCK)
  458                         printf("acctwatch: sleep error %d\n", error);
  459 #endif
  460         }
  461         acct_dkwatcher = NULL;
  462         ACCT_UNLOCK();
  463 
  464         kthread_exit(0);
  465 }

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