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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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_acct.c

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    1 /*-
    2  * Copyright (c) 1994 Christopher G. Demetriou
    3  * Copyright (c) 1982, 1986, 1989, 1993
    4  *      The Regents of the University of California.  All rights reserved.
    5  * (c) UNIX System Laboratories, Inc.
    6  * All or some portions of this file are derived from material licensed
    7  * to the University of California by American Telephone and Telegraph
    8  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
    9  * the permission of UNIX System Laboratories, Inc.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  * 3. All advertising materials mentioning features or use of this software
   20  *    must display the following acknowledgement:
   21  *      This product includes software developed by the University of
   22  *      California, Berkeley and its contributors.
   23  * 4. Neither the name of the University nor the names of its contributors
   24  *    may be used to endorse or promote products derived from this software
   25  *    without specific prior written permission.
   26  *
   27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   37  * SUCH DAMAGE.
   38  *
   39  *      @(#)kern_acct.c 8.1 (Berkeley) 6/14/93
   40  * $FreeBSD$
   41  */
   42 
   43 #include <sys/param.h>
   44 #include <sys/systm.h>
   45 #include <sys/sysproto.h>
   46 #include <sys/proc.h>
   47 #include <sys/mount.h>
   48 #include <sys/vnode.h>
   49 #include <sys/fcntl.h>
   50 #include <sys/syslog.h>
   51 #include <sys/kernel.h>
   52 #include <sys/sysent.h>
   53 #include <sys/sysctl.h>
   54 #include <sys/namei.h>
   55 #include <sys/acct.h>
   56 #include <sys/resourcevar.h>
   57 #include <sys/tty.h>
   58 
   59 /*
   60  * The routines implemented in this file are described in:
   61  *      Leffler, et al.: The Design and Implementation of the 4.3BSD
   62  *          UNIX Operating System (Addison Welley, 1989)
   63  * on pages 62-63.
   64  *
   65  * Arguably, to simplify accounting operations, this mechanism should
   66  * be replaced by one in which an accounting log file (similar to /dev/klog)
   67  * is read by a user process, etc.  However, that has its own problems.
   68  */
   69 
   70 /*
   71  * Internal accounting functions.
   72  * The former's operation is described in Leffler, et al., and the latter
   73  * was provided by UCB with the 4.4BSD-Lite release
   74  */
   75 static comp_t   encode_comp_t __P((u_long, u_long));
   76 static void     acctwatch __P((void *));
   77 
   78 /*
   79  * Accounting callout handle used for periodic scheduling of
   80  * acctwatch.
   81  */
   82 static struct   callout_handle acctwatch_handle
   83     = CALLOUT_HANDLE_INITIALIZER(&acctwatch_handle);
   84 
   85 /*
   86  * Accounting vnode pointer, and saved vnode pointer.
   87  */
   88 static struct   vnode *acctp;
   89 static struct   vnode *savacctp;
   90 
   91 /*
   92  * Values associated with enabling and disabling accounting
   93  */
   94 static int acctsuspend = 2;     /* stop accounting when < 2% free space left */
   95 SYSCTL_INT(_kern, OID_AUTO, acct_suspend, CTLFLAG_RW,
   96         &acctsuspend, 0, "");
   97 
   98 static int acctresume = 4;      /* resume when free space risen to > 4% */
   99 SYSCTL_INT(_kern, OID_AUTO, acct_resume, CTLFLAG_RW,
  100         &acctresume, 0, "");
  101 
  102 static int acctchkfreq = 15;    /* frequency (in seconds) to check space */
  103 SYSCTL_INT(_kern, OID_AUTO, acct_chkfreq, CTLFLAG_RW,
  104         &acctchkfreq, 0, "");
  105 
  106 /*
  107  * Accounting system call.  Written based on the specification and
  108  * previous implementation done by Mark Tinguely.
  109  */
  110 int
  111 acct(a1, uap)
  112         struct proc *a1;
  113         struct acct_args /* {
  114                 syscallarg(char *) path;
  115         } */ *uap;
  116 {
  117         struct proc *p = curproc;       /* XXX */
  118         struct nameidata nd;
  119         int error;
  120 
  121         /* Make sure that the caller is root. */
  122         error = suser(p->p_ucred, &p->p_acflag);
  123         if (error)
  124                 return (error);
  125 
  126         /*
  127          * If accounting is to be started to a file, open that file for
  128          * writing and make sure it's a 'normal'.
  129          */
  130         if (SCARG(uap, path) != NULL) {
  131                 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, SCARG(uap, path),
  132                        p);
  133                 error = vn_open(&nd, FWRITE, 0);
  134                 if (error)
  135                         return (error);
  136                 VOP_UNLOCK(nd.ni_vp, 0, p);
  137                 if (nd.ni_vp->v_type != VREG) {
  138                         vn_close(nd.ni_vp, FWRITE, p->p_ucred, p);
  139                         return (EACCES);
  140                 }
  141         }
  142 
  143         /*
  144          * If accounting was previously enabled, kill the old space-watcher,
  145          * close the file, and (if no new file was specified, leave).
  146          */
  147         if (acctp != NULLVP || savacctp != NULLVP) {
  148                 untimeout(acctwatch, NULL, acctwatch_handle);
  149                 error = vn_close((acctp != NULLVP ? acctp : savacctp), FWRITE,
  150                     p->p_ucred, p);
  151                 acctp = savacctp = NULLVP;
  152         }
  153         if (SCARG(uap, path) == NULL)
  154                 return (error);
  155 
  156         /*
  157          * Save the new accounting file vnode, and schedule the new
  158          * free space watcher.
  159          */
  160         acctp = nd.ni_vp;
  161         acctwatch(NULL);
  162         return (error);
  163 }
  164 
  165 /*
  166  * Write out process accounting information, on process exit.
  167  * Data to be written out is specified in Leffler, et al.
  168  * and are enumerated below.  (They're also noted in the system
  169  * "acct.h" header file.)
  170  */
  171 
  172 int
  173 acct_process(p)
  174         struct proc *p;
  175 {
  176         struct acct acct;
  177         struct rusage *r;
  178         struct timeval ut, st, tmp;
  179         int t;
  180         struct vnode *vp;
  181 
  182         /* If accounting isn't enabled, don't bother */
  183         vp = acctp;
  184         if (vp == NULLVP)
  185                 return (0);
  186 
  187         /*
  188          * Get process accounting information.
  189          */
  190 
  191         /* (1) The name of the command that ran */
  192         bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm);
  193 
  194         /* (2) The amount of user and system time that was used */
  195         calcru(p, &ut, &st, NULL);
  196         acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_usec);
  197         acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_usec);
  198 
  199         /* (3) The elapsed time the commmand ran (and its starting time) */
  200         acct.ac_btime = p->p_stats->p_start.tv_sec;
  201         microtime(&tmp);
  202         timevalsub(&tmp, &p->p_stats->p_start);
  203         acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);
  204 
  205         /* (4) The average amount of memory used */
  206         r = &p->p_stats->p_ru;
  207         tmp = ut;
  208         timevaladd(&tmp, &st);
  209         t = tmp.tv_sec * hz + tmp.tv_usec / tick;
  210         if (t)
  211                 acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
  212         else
  213                 acct.ac_mem = 0;
  214 
  215         /* (5) The number of disk I/O operations done */
  216         acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
  217 
  218         /* (6) The UID and GID of the process */
  219         acct.ac_uid = p->p_cred->p_ruid;
  220         acct.ac_gid = p->p_cred->p_rgid;
  221 
  222         /* (7) The terminal from which the process was started */
  223         if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
  224                 acct.ac_tty = p->p_pgrp->pg_session->s_ttyp->t_dev;
  225         else
  226                 acct.ac_tty = NODEV;
  227 
  228         /* (8) The boolean flags that tell how the process terminated, etc. */
  229         acct.ac_flag = p->p_acflag;
  230 
  231         /*
  232          * Eliminate any file size rlimit.
  233          */
  234         if (p->p_limit->p_refcnt > 1 &&
  235             (p->p_limit->p_lflags & PL_SHAREMOD) == 0) {
  236                 p->p_limit->p_refcnt--;
  237                 p->p_limit = limcopy(p->p_limit);
  238         } 
  239         p->p_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
  240 
  241         /*
  242          * Write the accounting information to the file.
  243          */
  244         VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
  245         return (vn_rdwr(UIO_WRITE, vp, (caddr_t)&acct, sizeof (acct),
  246             (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, p->p_ucred,
  247             (int *)0, p));
  248 }
  249 
  250 /*
  251  * Encode_comp_t converts from ticks in seconds and microseconds
  252  * to ticks in 1/AHZ seconds.  The encoding is described in
  253  * Leffler, et al., on page 63.
  254  */
  255 
  256 #define MANTSIZE        13                      /* 13 bit mantissa. */
  257 #define EXPSIZE         3                       /* Base 8 (3 bit) exponent. */
  258 #define MAXFRACT        ((1 << MANTSIZE) - 1)   /* Maximum fractional value. */
  259 
  260 static comp_t
  261 encode_comp_t(s, us)
  262         u_long s, us;
  263 {
  264         int exp, rnd;
  265 
  266         exp = 0;
  267         rnd = 0;
  268         s *= AHZ;
  269         s += us / (1000000 / AHZ);      /* Maximize precision. */
  270 
  271         while (s > MAXFRACT) {
  272         rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
  273                 s >>= EXPSIZE;          /* Base 8 exponent == 3 bit shift. */
  274                 exp++;
  275         }
  276 
  277         /* If we need to round up, do it (and handle overflow correctly). */
  278         if (rnd && (++s > MAXFRACT)) {
  279                 s >>= EXPSIZE;
  280                 exp++;
  281         }
  282 
  283         /* Clean it up and polish it off. */
  284         exp <<= MANTSIZE;               /* Shift the exponent into place */
  285         exp += s;                       /* and add on the mantissa. */
  286         return (exp);
  287 }
  288 
  289 /*
  290  * Periodically check the file system to see if accounting
  291  * should be turned on or off.  Beware the case where the vnode
  292  * has been vgone()'d out from underneath us, e.g. when the file
  293  * system containing the accounting file has been forcibly unmounted.
  294  */
  295 /* ARGSUSED */
  296 static void
  297 acctwatch(a)
  298         void *a;
  299 {
  300         struct statfs sb;
  301 
  302         if (savacctp != NULLVP) {
  303                 if (savacctp->v_type == VBAD) {
  304                         (void) vn_close(savacctp, FWRITE, NOCRED, NULL);
  305                         savacctp = NULLVP;
  306                         return;
  307                 }
  308                 (void)VFS_STATFS(savacctp->v_mount, &sb, (struct proc *)0);
  309                 if (sb.f_bavail > acctresume * sb.f_blocks / 100) {
  310                         acctp = savacctp;
  311                         savacctp = NULLVP;
  312                         log(LOG_NOTICE, "Accounting resumed\n");
  313                 }
  314         } else {
  315                 if (acctp == NULLVP)
  316                         return;
  317                 if (acctp->v_type == VBAD) {
  318                         (void) vn_close(acctp, FWRITE, NOCRED, NULL);
  319                         acctp = NULLVP;
  320                         return;
  321                 }
  322                 (void)VFS_STATFS(acctp->v_mount, &sb, (struct proc *)0);
  323                 if (sb.f_bavail <= acctsuspend * sb.f_blocks / 100) {
  324                         savacctp = acctp;
  325                         acctp = NULLVP;
  326                         log(LOG_NOTICE, "Accounting suspended\n");
  327                 }
  328         }
  329         acctwatch_handle = timeout(acctwatch, NULL, acctchkfreq * hz);
  330 }

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