Annotation of sys/kern/kern_acct.c, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: kern_acct.c,v 1.21 2007/04/12 22:14:15 tedu Exp $ */
2: /* $NetBSD: kern_acct.c,v 1.42 1996/02/04 02:15:12 christos Exp $ */
3:
4: /*-
5: * Copyright (c) 1994 Christopher G. Demetriou
6: * Copyright (c) 1982, 1986, 1989, 1993
7: * The Regents of the University of California. All rights reserved.
8: * (c) UNIX System Laboratories, Inc.
9: * All or some portions of this file are derived from material licensed
10: * to the University of California by American Telephone and Telegraph
11: * Co. or Unix System Laboratories, Inc. and are reproduced herein with
12: * the permission of UNIX System Laboratories, Inc.
13: *
14: * Redistribution and use in source and binary forms, with or without
15: * modification, are permitted provided that the following conditions
16: * are met:
17: * 1. Redistributions of source code must retain the above copyright
18: * notice, this list of conditions and the following disclaimer.
19: * 2. Redistributions in binary form must reproduce the above copyright
20: * notice, this list of conditions and the following disclaimer in the
21: * documentation and/or other materials provided with the distribution.
22: * 3. Neither the name of the University nor the names of its contributors
23: * may be used to endorse or promote products derived from this software
24: * without specific prior written permission.
25: *
26: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36: * SUCH DAMAGE.
37: *
38: * @(#)kern_acct.c 8.1 (Berkeley) 6/14/93
39: */
40:
41: #include <sys/param.h>
42: #include <sys/systm.h>
43: #include <sys/proc.h>
44: #include <sys/mount.h>
45: #include <sys/vnode.h>
46: #include <sys/file.h>
47: #include <sys/syslog.h>
48: #include <sys/kernel.h>
49: #include <sys/namei.h>
50: #include <sys/errno.h>
51: #include <sys/acct.h>
52: #include <sys/resourcevar.h>
53: #include <sys/ioctl.h>
54: #include <sys/tty.h>
55: #include <sys/kthread.h>
56:
57: #include <sys/syscallargs.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: */
73: comp_t encode_comp_t(u_long, u_long);
74: int acct_start(void);
75: void acct_thread(void *);
76: void acct_shutdown(void);
77:
78: /*
79: * Accounting vnode pointer, and saved vnode pointer.
80: */
81: struct vnode *acctp;
82: struct vnode *savacctp;
83:
84: /*
85: * Values associated with enabling and disabling accounting
86: */
87: int acctsuspend = 2; /* stop accounting when < 2% free space left */
88: int acctresume = 4; /* resume when free space risen to > 4% */
89: int acctchkfreq = 15; /* frequency (in seconds) to check space */
90:
91: struct proc *acct_proc;
92:
93: /*
94: * Accounting system call. Written based on the specification and
95: * previous implementation done by Mark Tinguely.
96: */
97: int
98: sys_acct(struct proc *p, void *v, register_t *retval)
99: {
100: struct sys_acct_args /* {
101: syscallarg(const char *) path;
102: } */ *uap = v;
103: struct nameidata nd;
104: int error;
105:
106: /* Make sure that the caller is root. */
107: if ((error = suser(p, 0)) != 0)
108: return (error);
109:
110: /*
111: * If accounting is to be started to a file, open that file for
112: * writing and make sure it's 'normal'.
113: */
114: if (SCARG(uap, path) != NULL) {
115: NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, SCARG(uap, path),
116: p);
117: if ((error = vn_open(&nd, FWRITE|O_APPEND, 0)) != 0)
118: return (error);
119: VOP_UNLOCK(nd.ni_vp, 0, p);
120: if (nd.ni_vp->v_type != VREG) {
121: vn_close(nd.ni_vp, FWRITE, p->p_ucred, p);
122: return (EACCES);
123: }
124: }
125:
126: /*
127: * If accounting was previously enabled, kill the old space-watcher,
128: * close the file, and (if no new file was specified, leave).
129: */
130: if (acctp != NULL || savacctp != NULL) {
131: wakeup(&acct_proc);
132: error = vn_close((acctp != NULL ? acctp : savacctp), FWRITE,
133: p->p_ucred, p);
134: acctp = savacctp = NULL;
135: }
136: if (SCARG(uap, path) == NULL)
137: return (0);
138:
139: /*
140: * Save the new accounting file vnode, and schedule the new
141: * free space watcher.
142: */
143: acctp = nd.ni_vp;
144: if ((error = acct_start()) != 0) {
145: acctp = NULL;
146: (void)vn_close(nd.ni_vp, FWRITE, p->p_ucred, p);
147: return (error);
148: }
149: return (0);
150: }
151:
152: /*
153: * Write out process accounting information, on process exit.
154: * Data to be written out is specified in Leffler, et al.
155: * and are enumerated below. (They're also noted in the system
156: * "acct.h" header file.)
157: */
158: int
159: acct_process(struct proc *p)
160: {
161: struct acct acct;
162: struct rusage *r;
163: struct timeval ut, st, tmp;
164: int t;
165: struct vnode *vp;
166: struct plimit *oplim = NULL;
167: int error;
168:
169: /* If accounting isn't enabled, don't bother */
170: vp = acctp;
171: if (vp == NULL)
172: return (0);
173:
174: /*
175: * Raise the file limit so that accounting can't be stopped by the
176: * user. (XXX - we should think about the cpu limit too).
177: */
178: if (p->p_p->ps_limit->p_refcnt > 1) {
179: oplim = p->p_p->ps_limit;
180: p->p_p->ps_limit = limcopy(p->p_p->ps_limit);
181: }
182: p->p_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
183:
184: /*
185: * Get process accounting information.
186: */
187:
188: /* (1) The name of the command that ran */
189: bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm);
190:
191: /* (2) The amount of user and system time that was used */
192: calcru(p, &ut, &st, NULL);
193: acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_usec);
194: acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_usec);
195:
196: /* (3) The elapsed time the commmand ran (and its starting time) */
197: acct.ac_btime = p->p_stats->p_start.tv_sec;
198: getmicrotime(&tmp);
199: timersub(&tmp, &p->p_stats->p_start, &tmp);
200: acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);
201:
202: /* (4) The average amount of memory used */
203: r = &p->p_stats->p_ru;
204: timeradd(&ut, &st, &tmp);
205: t = tmp.tv_sec * hz + tmp.tv_usec / tick;
206: if (t)
207: acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
208: else
209: acct.ac_mem = 0;
210:
211: /* (5) The number of disk I/O operations done */
212: acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
213:
214: /* (6) The UID and GID of the process */
215: acct.ac_uid = p->p_cred->p_ruid;
216: acct.ac_gid = p->p_cred->p_rgid;
217:
218: /* (7) The terminal from which the process was started */
219: if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
220: acct.ac_tty = p->p_pgrp->pg_session->s_ttyp->t_dev;
221: else
222: acct.ac_tty = NODEV;
223:
224: /* (8) The boolean flags that tell how the process terminated, etc. */
225: acct.ac_flag = p->p_acflag;
226:
227: /*
228: * Now, just write the accounting information to the file.
229: */
230: error = vn_rdwr(UIO_WRITE, vp, (caddr_t)&acct, sizeof (acct),
231: (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, p->p_ucred, NULL, p);
232:
233: if (oplim) {
234: limfree(p->p_p->ps_limit);
235: p->p_p->ps_limit = oplim;
236: }
237:
238: return error;
239: }
240:
241: /*
242: * Encode_comp_t converts from ticks in seconds and microseconds
243: * to ticks in 1/AHZ seconds. The encoding is described in
244: * Leffler, et al., on page 63.
245: */
246:
247: #define MANTSIZE 13 /* 13 bit mantissa. */
248: #define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
249: #define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */
250:
251: comp_t
252: encode_comp_t(u_long s, u_long us)
253: {
254: int exp, rnd;
255:
256: exp = 0;
257: rnd = 0;
258: s *= AHZ;
259: s += us / (1000000 / AHZ); /* Maximize precision. */
260:
261: while (s > MAXFRACT) {
262: rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
263: s >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */
264: exp++;
265: }
266:
267: /* If we need to round up, do it (and handle overflow correctly). */
268: if (rnd && (++s > MAXFRACT)) {
269: s >>= EXPSIZE;
270: exp++;
271: }
272:
273: /* Clean it up and polish it off. */
274: exp <<= MANTSIZE; /* Shift the exponent into place */
275: exp += s; /* and add on the mantissa. */
276: return (exp);
277: }
278:
279: int
280: acct_start(void)
281: {
282: /* Already running. */
283: if (acct_proc != NULL)
284: return (0);
285:
286: return (kthread_create(acct_thread, NULL, &acct_proc, "acct"));
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: void
297: acct_thread(void *arg)
298: {
299: struct statfs sb;
300: struct proc *p = curproc;
301:
302: for (;;) {
303: if (savacctp != NULL) {
304: if (savacctp->v_type == VBAD) {
305: (void) vn_close(savacctp, FWRITE, NOCRED, p);
306: savacctp = NULL;
307: break;
308: }
309: (void)VFS_STATFS(savacctp->v_mount, &sb, (struct proc *)0);
310: if (sb.f_bavail > acctresume * sb.f_blocks / 100) {
311: acctp = savacctp;
312: savacctp = NULL;
313: log(LOG_NOTICE, "Accounting resumed\n");
314: }
315: } else if (acctp != NULL) {
316: if (acctp->v_type == VBAD) {
317: (void) vn_close(acctp, FWRITE, NOCRED, p);
318: acctp = NULL;
319: break;
320: }
321: (void)VFS_STATFS(acctp->v_mount, &sb, (struct proc *)0);
322: if (sb.f_bavail <= acctsuspend * sb.f_blocks / 100) {
323: savacctp = acctp;
324: acctp = NULL;
325: log(LOG_NOTICE, "Accounting suspended\n");
326: }
327: } else {
328: break;
329: }
330: tsleep(&acct_proc, PPAUSE, "acct", acctchkfreq *hz);
331: }
332: acct_proc = NULL;
333: kthread_exit(0);
334: }
335:
336: void
337: acct_shutdown(void)
338: {
339:
340: struct proc *p = curproc;
341:
342: if (acctp != NULL || savacctp != NULL) {
343: vn_close((acctp != NULL ? acctp : savacctp), FWRITE,
344: NOCRED, p);
345: acctp = savacctp = NULL;
346: }
347: }
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