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

     /*      $NetBSD: kern_acct.c,v 1.60 2004/12/13 08:46:43 yamt Exp $      */
     
     /*-
      * Copyright (c) 1982, 1986, 1989, 1993
      *      The Regents of the University of California.  All rights reserved.
      * (c) UNIX System Laboratories, Inc.
      * All or some portions of this file are derived from material licensed
      * to the University of California by American Telephone and Telegraph
      * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     * the permission of UNIX System Laboratories, Inc.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)kern_acct.c 8.8 (Berkeley) 5/14/95
     */
    
    /*-
     * Copyright (c) 1994 Christopher G. Demetriou
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)kern_acct.c 8.8 (Berkeley) 5/14/95
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: kern_acct.c,v 1.60 2004/12/13 08:46:43 yamt Exp $");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/proc.h>
    #include <sys/mount.h>
    #include <sys/vnode.h>
    #include <sys/file.h>
    #include <sys/syslog.h>
    #include <sys/kernel.h>
    #include <sys/kthread.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/namei.h>
    #include <sys/errno.h>
    #include <sys/acct.h>
    #include <sys/resourcevar.h>
    #include <sys/ioctl.h>
    #include <sys/tty.h>
    
    #include <sys/sa.h>
    #include <sys/syscallargs.h>
    
    /*
     * The routines implemented in this file are described in:
     *      Leffler, et al.: The Design and Implementation of the 4.3BSD
    *          UNIX Operating System (Addison Welley, 1989)
    * on pages 62-63.
    *
    * Arguably, to simplify accounting operations, this mechanism should
    * be replaced by one in which an accounting log file (similar to /dev/klog)
    * is read by a user process, etc.  However, that has its own problems.
    */
   
   /*
    * The global accounting state and related data.  Gain the lock before
    * accessing these variables.
    */
   enum {
           ACCT_STOP,
           ACCT_ACTIVE,
           ACCT_SUSPENDED
   } acct_state;                           /* The current accounting state. */
   struct vnode *acct_vp;                  /* Accounting vnode pointer. */
   struct ucred *acct_ucred;               /* Credential of accounting file
                                              owner (i.e root).  Used when
                                              accounting file i/o.  */
   struct proc *acct_dkwatcher;            /* Free disk space checker. */
   
   /*
    * Lock to serialize system calls and kernel threads.
    */
   struct  lock acct_lock;
   #define ACCT_LOCK()                                             \
   do {                                                            \
           (void) lockmgr(&acct_lock, LK_EXCLUSIVE, NULL);         \
   } while (/* CONSTCOND */0)
   #define ACCT_UNLOCK()                                           \
   do {                                                            \
           (void) lockmgr(&acct_lock, LK_RELEASE, NULL);           \
   } while (/* CONSTCOND */0)
   
   /*
    * Internal accounting functions.
    * The former's operation is described in Leffler, et al., and the latter
    * was provided by UCB with the 4.4BSD-Lite release
    */
   comp_t  encode_comp_t(u_long, u_long);
   void    acctwatch(void *);
   void    acct_stop(void);
   int     acct_chkfree(void);
   
   /*
    * Values associated with enabling and disabling accounting
    */
   int     acctsuspend = 2;        /* stop accounting when < 2% free space left */
   int     acctresume = 4;         /* resume when free space risen to > 4% */
   int     acctchkfreq = 15;       /* frequency (in seconds) to check space */
   
   void
   acct_init()
   {
   
           acct_state = ACCT_STOP;
           acct_vp = NULLVP;
           acct_ucred = NULL;
           lockinit(&acct_lock, PWAIT, "acctlk", 0, 0);
   }
   
   void
   acct_stop()
   {
           int error;
   
           if (acct_vp != NULLVP && acct_vp->v_type != VBAD) {
                   error = vn_close(acct_vp, FWRITE, acct_ucred, NULL);
   #ifdef DIAGNOSTIC
                   if (error != 0)
                           printf("acct_stop: failed to close, errno = %d\n",
                               error);
   #endif
                   acct_vp = NULLVP;
           }
           if (acct_ucred != NULL) {
                   crfree(acct_ucred);
                   acct_ucred = NULL;
           }
           acct_state = ACCT_STOP;
   }
   
   int
   acct_chkfree()
   {
           int error;
           struct statvfs sb;
           int64_t bavail;
   
           error = VFS_STATVFS(acct_vp->v_mount, &sb, NULL);
           if (error != 0)
                   return (error);
   
           bavail = sb.f_bfree - sb.f_bresvd;
   
           switch (acct_state) {
           case ACCT_SUSPENDED:
                   if (bavail > acctresume * sb.f_blocks / 100) {
                           acct_state = ACCT_ACTIVE;
                           log(LOG_NOTICE, "Accounting resumed\n");
                   }
                   break;
           case ACCT_ACTIVE:
                   if (bavail <= acctsuspend * sb.f_blocks / 100) {
                           acct_state = ACCT_SUSPENDED;
                           log(LOG_NOTICE, "Accounting suspended\n");
                   }
                   break;
           case ACCT_STOP:
                   break;
           }
           return (0);
   }
   
   /*
    * Accounting system call.  Written based on the specification and
    * previous implementation done by Mark Tinguely.
    */
   int
   sys_acct(l, v, retval)
           struct lwp *l;
           void *v;
           register_t *retval;
   {
           struct sys_acct_args /* {
                   syscallarg(const char *) path;
           } */ *uap = v;
           struct nameidata nd;
           int error;
           struct proc *p = l->l_proc;
   
           /* Make sure that the caller is root. */
           if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
                   return (error);
   
           /*
            * If accounting is to be started to a file, open that file for
            * writing and make sure it's a 'normal'.
            */
           if (SCARG(uap, path) != NULL) {
                   struct vattr va;
                   size_t pad;
                   NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, SCARG(uap, path),
                       p);
                   if ((error = vn_open(&nd, FWRITE|O_APPEND, 0)) != 0)
                           return (error);
                   if (nd.ni_vp->v_type != VREG) {
                           VOP_UNLOCK(nd.ni_vp, 0);
                           error = EACCES;
                           goto bad;
                   }
                   if ((error = VOP_GETATTR(nd.ni_vp, &va, p->p_ucred, p)) != 0) {
                           VOP_UNLOCK(nd.ni_vp, 0);
                           goto bad;
                   }
   
                   if ((pad = (va.va_size % sizeof(struct acct))) != 0) {
                           u_quad_t size = va.va_size - pad;
   #ifdef DIAGNOSTIC
                           printf("Size of accounting file not a multiple of "
                               "%lu - incomplete record truncated\n",
                               (unsigned long)sizeof(struct acct));
   #endif
                           VATTR_NULL(&va);
                           va.va_size = size;
                           error = VOP_SETATTR(nd.ni_vp, &va, p->p_ucred, p);
                           if (error != 0) {
                                   VOP_UNLOCK(nd.ni_vp, 0);
                                   goto bad;
                           }
                   }
                   VOP_UNLOCK(nd.ni_vp, 0);
           }
   
           ACCT_LOCK();
   
           /*
            * If accounting was previously enabled, kill the old space-watcher,
            * free credential for accounting file i/o,
            * ... (and, if no new file was specified, leave).
            */
           acct_stop();
           if (SCARG(uap, path) == NULL)
                   goto out;
   
           /*
            * Save the new accounting file vnode and credential,
            * and schedule the new free space watcher.
            */
           acct_state = ACCT_ACTIVE;
           acct_vp = nd.ni_vp;
           acct_ucred = p->p_ucred;
           crhold(acct_ucred);
   
           error = acct_chkfree();         /* Initial guess. */
           if (error != 0) {
                   acct_stop();
                   goto out;
           }
   
           if (acct_dkwatcher == NULL) {
                   error = kthread_create1(acctwatch, NULL, &acct_dkwatcher,
                       "acctwatch");
                   if (error != 0)
                           acct_stop();
           }
   
    out:
           ACCT_UNLOCK();
           return (error);
    bad:
           vn_close(nd.ni_vp, FWRITE, p->p_ucred, p);
           return error;
   }
   
   /*
    * Write out process accounting information, on process exit.
    * Data to be written out is specified in Leffler, et al.
    * and are enumerated below.  (They're also noted in the system
    * "acct.h" header file.)
    */
   int
   acct_process(p)
           struct proc *p;
   {
           struct acct acct;
           struct rusage *r;
           struct timeval ut, st, tmp;
           int s, t, error = 0;
           struct plimit *oplim = NULL;
   
           ACCT_LOCK();
   
           /* If accounting isn't enabled, don't bother */
           if (acct_state != ACCT_ACTIVE)
                   goto out;
   
           /*
            * Raise the file limit so that accounting can't be stopped by
            * the user.
            *
            * XXX We should think about the CPU limit, too.
            */
           if (p->p_limit->p_refcnt > 1) {
                   oplim = p->p_limit;
                   p->p_limit = limcopy(p->p_limit);
           }
           p->p_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
   
           /*
            * Get process accounting information.
            */
   
           /* (1) The name of the command that ran */
           memcpy(acct.ac_comm, p->p_comm, sizeof(acct.ac_comm));
   
           /* (2) The amount of user and system time that was used */
           calcru(p, &ut, &st, NULL);
           acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_usec);
           acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_usec);
   
           /* (3) The elapsed time the commmand ran (and its starting time) */
           acct.ac_btime = p->p_stats->p_start.tv_sec;
           s = splclock();
           timersub(&time, &p->p_stats->p_start, &tmp);
           splx(s);
           acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);
   
           /* (4) The average amount of memory used */
           r = &p->p_stats->p_ru;
           timeradd(&ut, &st, &tmp);
           t = tmp.tv_sec * hz + tmp.tv_usec / tick;
           if (t)
                   acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
           else
                   acct.ac_mem = 0;
   
           /* (5) The number of disk I/O operations done */
           acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
   
           /* (6) The UID and GID of the process */
           acct.ac_uid = p->p_cred->p_ruid;
           acct.ac_gid = p->p_cred->p_rgid;
   
           /* (7) The terminal from which the process was started */
           if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
                   acct.ac_tty = p->p_pgrp->pg_session->s_ttyp->t_dev;
           else
                   acct.ac_tty = NODEV;
   
           /* (8) The boolean flags that tell how the process terminated, etc. */
           acct.ac_flag = p->p_acflag;
   
           /*
            * Now, just write the accounting information to the file.
            */
           VOP_LEASE(acct_vp, p, p->p_ucred, LEASE_WRITE);
           error = vn_rdwr(UIO_WRITE, acct_vp, (caddr_t)&acct,
               sizeof(acct), (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT,
               acct_ucred, NULL, NULL);
           if (error != 0)
                   log(LOG_ERR, "Accounting: write failed %d\n", error);
   
           if (oplim) {
                   limfree(p->p_limit);
                   p->p_limit = oplim;
           }
   
    out:
           ACCT_UNLOCK();
           return (error);
   }
   
   /*
    * Encode_comp_t converts from ticks in seconds and microseconds
    * to ticks in 1/AHZ seconds.  The encoding is described in
    * Leffler, et al., on page 63.
    */
   
   #define MANTSIZE        13                      /* 13 bit mantissa. */
   #define EXPSIZE         3                       /* Base 8 (3 bit) exponent. */
   #define MAXFRACT        ((1 << MANTSIZE) - 1)   /* Maximum fractional value. */
   
   comp_t
   encode_comp_t(s, us)
           u_long s, us;
   {
           int exp, rnd;
   
           exp = 0;
           rnd = 0;
           s *= AHZ;
           s += us / (1000000 / AHZ);      /* Maximize precision. */
   
           while (s > MAXFRACT) {
           rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
                   s >>= EXPSIZE;          /* Base 8 exponent == 3 bit shift. */
                   exp++;
           }
   
           /* If we need to round up, do it (and handle overflow correctly). */
           if (rnd && (++s > MAXFRACT)) {
                   s >>= EXPSIZE;
                   exp++;
           }
   
           /* Clean it up and polish it off. */
           exp <<= MANTSIZE;               /* Shift the exponent into place */
           exp += s;                       /* and add on the mantissa. */
           return (exp);
   }
   
   /*
    * Periodically check the file system to see if accounting
    * should be turned on or off.  Beware the case where the vnode
    * has been vgone()'d out from underneath us, e.g. when the file
    * system containing the accounting file has been forcibly unmounted.
    */
   void
   acctwatch(arg)
           void *arg;
   {
           int error;
   
           log(LOG_NOTICE, "Accounting started\n");
           ACCT_LOCK();
           while (acct_state != ACCT_STOP) {
                   if (acct_vp->v_type == VBAD) {
                           log(LOG_NOTICE, "Accounting terminated\n");
                           acct_stop();
                           continue;
                   }
   
                   error = acct_chkfree();
   #ifdef DIAGNOSTIC
                   if (error != 0)
                           printf("acctwatch: failed to statvfs, error = %d\n",
                               error);
   #endif
   
                   ACCT_UNLOCK();
                   error = tsleep(acctwatch, PSWP, "actwat", acctchkfreq * hz);
                   ACCT_LOCK();
   #ifdef DIAGNOSTIC
                   if (error != 0 && error != EWOULDBLOCK)
                           printf("acctwatch: sleep error %d\n", error);
   #endif
           }
           acct_dkwatcher = NULL;
           ACCT_UNLOCK();
   
           kthread_exit(0);
   }

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