xref: /netbsd-src/sys/kern/subr_prf.c (revision 53b02e147d4ed531c0d2a5ca9b3e8026ba3e99b5)
1 /*	$NetBSD: subr_prf.c,v 1.186 2021/03/10 13:27:51 simonb Exp $	*/
2 
3 /*-
4  * Copyright (c) 1986, 1988, 1991, 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  *	@(#)subr_prf.c	8.4 (Berkeley) 5/4/95
37  */
38 
39 #include <sys/cdefs.h>
40 __KERNEL_RCSID(0, "$NetBSD: subr_prf.c,v 1.186 2021/03/10 13:27:51 simonb Exp $");
41 
42 #ifdef _KERNEL_OPT
43 #include "opt_ddb.h"
44 #include "opt_kgdb.h"
45 #include "opt_dump.h"
46 #include "opt_rnd_printf.h"
47 #endif
48 
49 #include <sys/param.h>
50 #include <sys/stdint.h>
51 #include <sys/systm.h>
52 #include <sys/buf.h>
53 #include <sys/device.h>
54 #include <sys/reboot.h>
55 #include <sys/msgbuf.h>
56 #include <sys/proc.h>
57 #include <sys/ioctl.h>
58 #include <sys/vnode.h>
59 #include <sys/file.h>
60 #include <sys/tty.h>
61 #include <sys/tprintf.h>
62 #include <sys/spldebug.h>
63 #include <sys/syslog.h>
64 #include <sys/kprintf.h>
65 #include <sys/atomic.h>
66 #include <sys/kernel.h>
67 #include <sys/cpu.h>
68 #include <sys/rndsource.h>
69 #include <sys/kmem.h>
70 
71 #include <dev/cons.h>
72 
73 #include <net/if.h>
74 
75 static kmutex_t kprintf_mtx;
76 static bool kprintf_inited = false;
77 
78 #ifdef KGDB
79 #include <sys/kgdb.h>
80 #endif
81 
82 #ifdef DDB
83 #include <ddb/ddbvar.h>		/* db_panic */
84 #include <ddb/db_output.h>	/* db_printf, db_putchar prototypes */
85 #endif
86 
87 
88 /*
89  * defines
90  */
91 #define KLOG_PRI	0x80000000
92 
93 
94 /*
95  * local prototypes
96  */
97 
98 static void	 putchar(int, int, struct tty *);
99 
100 
101 /*
102  * globals
103  */
104 
105 extern	struct tty *constty;	/* pointer to console "window" tty */
106 extern	int log_open;	/* subr_log: is /dev/klog open? */
107 const	char *panicstr; /* arg to first call to panic (used as a flag
108 			   to indicate that panic has already been called). */
109 struct cpu_info *paniccpu;	/* cpu that first paniced */
110 long	panicstart, panicend;	/* position in the msgbuf of the start and
111 				   end of the formatted panicstr. */
112 int	doing_shutdown;	/* set to indicate shutdown in progress */
113 
114 #ifdef RND_PRINTF
115 static krndsource_t	rnd_printf_source;
116 #endif
117 
118 #ifndef	DUMP_ON_PANIC
119 #define	DUMP_ON_PANIC	1
120 #endif
121 int	dumponpanic = DUMP_ON_PANIC;
122 
123 /*
124  * v_putc: routine to putc on virtual console
125  *
126  * the v_putc pointer can be used to redirect the console cnputc elsewhere
127  * [e.g. to a "virtual console"].
128  */
129 
130 void (*v_putc)(int) = cnputc;	/* start with cnputc (normal cons) */
131 void (*v_flush)(void) = cnflush;	/* start with cnflush (normal cons) */
132 
133 const char hexdigits[] = "0123456789abcdef";
134 const char HEXDIGITS[] = "0123456789ABCDEF";
135 
136 
137 /*
138  * functions
139  */
140 
141 /*
142  * Locking is inited fairly early in MI bootstrap.  Before that
143  * prints are done unlocked.  But that doesn't really matter,
144  * since nothing can preempt us before interrupts are enabled.
145  */
146 void
147 kprintf_init(void)
148 {
149 
150 	KASSERT(!kprintf_inited && cold); /* not foolproof, but ... */
151 	mutex_init(&kprintf_mtx, MUTEX_DEFAULT, IPL_HIGH);
152 #ifdef RND_PRINTF
153 	rnd_attach_source(&rnd_printf_source, "printf", RND_TYPE_UNKNOWN,
154 	    RND_FLAG_COLLECT_TIME|RND_FLAG_COLLECT_VALUE);
155 #endif
156 	kprintf_inited = true;
157 }
158 
159 void
160 kprintf_lock(void)
161 {
162 
163 	if (__predict_true(kprintf_inited))
164 		mutex_enter(&kprintf_mtx);
165 }
166 
167 void
168 kprintf_unlock(void)
169 {
170 
171 	if (__predict_true(kprintf_inited)) {
172 		/* assert kprintf wasn't somehow inited while we were in */
173 		KASSERT(mutex_owned(&kprintf_mtx));
174 		mutex_exit(&kprintf_mtx);
175 	}
176 }
177 
178 /*
179  * twiddle: spin a little propellor on the console.
180  */
181 
182 void
183 twiddle(void)
184 {
185 	static const char twiddle_chars[] = "|/-\\";
186 	static int pos;
187 
188 	kprintf_lock();
189 
190 	putchar(twiddle_chars[pos++ & 3], TOCONS|NOTSTAMP, NULL);
191 	putchar('\b', TOCONS|NOTSTAMP, NULL);
192 
193 	kprintf_unlock();
194 }
195 
196 /*
197  * panic: handle an unresolvable fatal error
198  *
199  * prints "panic: <message>" and reboots.   if called twice (i.e. recursive
200  * call) we avoid trying to dump and just reboot (to avoid recursive panics).
201  */
202 
203 void
204 panic(const char *fmt, ...)
205 {
206 	va_list ap;
207 
208 	va_start(ap, fmt);
209 	vpanic(fmt, ap);
210 	va_end(ap);
211 }
212 
213 void
214 vpanic(const char *fmt, va_list ap)
215 {
216 	CPU_INFO_ITERATOR cii;
217 	struct cpu_info *ci, *oci;
218 	int bootopt;
219 	static char scratchstr[384]; /* stores panic message */
220 
221 	spldebug_stop();
222 
223 	if (lwp0.l_cpu && curlwp) {
224 		/*
225 		 * Disable preemption.  If already panicing on another CPU, sit
226 		 * here and spin until the system is rebooted.  Allow the CPU that
227 		 * first paniced to panic again.
228 		 */
229 		kpreempt_disable();
230 		ci = curcpu();
231 		oci = atomic_cas_ptr((void *)&paniccpu, NULL, ci);
232 		if (oci != NULL && oci != ci) {
233 			/* Give interrupts a chance to try and prevent deadlock. */
234 			for (;;) {
235 #ifndef _RUMPKERNEL /* XXXpooka: temporary build fix, see kern/40505 */
236 				DELAY(10);
237 #endif /* _RUMPKERNEL */
238 			}
239 		}
240 
241 		/*
242 		 * Convert the current thread to a bound thread and prevent all
243 		 * CPUs from scheduling unbound jobs.  Do so without taking any
244 		 * locks.
245 		 */
246 		curlwp->l_pflag |= LP_BOUND;
247 		for (CPU_INFO_FOREACH(cii, ci)) {
248 			ci->ci_schedstate.spc_flags |= SPCF_OFFLINE;
249 		}
250 	}
251 
252 	bootopt = RB_AUTOBOOT | RB_NOSYNC;
253 	if (!doing_shutdown) {
254 		if (dumponpanic)
255 			bootopt |= RB_DUMP;
256 	} else
257 		printf("Skipping crash dump on recursive panic\n");
258 
259 	doing_shutdown = 1;
260 
261 	if (logenabled(msgbufp))
262 		panicstart = msgbufp->msg_bufx;
263 
264 	printf("panic: ");
265 	if (panicstr == NULL) {
266 		/* first time in panic - store fmt first for precaution */
267 		panicstr = fmt;
268 
269 		vsnprintf(scratchstr, sizeof(scratchstr), fmt, ap);
270 		printf("%s", scratchstr);
271 		panicstr = scratchstr;
272 	} else {
273 		vprintf(fmt, ap);
274 	}
275 	printf("\n");
276 
277 	if (logenabled(msgbufp))
278 		panicend = msgbufp->msg_bufx;
279 
280 #ifdef KGDB
281 	kgdb_panic();
282 #endif
283 #ifdef KADB
284 	if (boothowto & RB_KDB)
285 		kdbpanic();
286 #endif
287 #ifdef DDB
288 	db_panic();
289 #endif
290 	kern_reboot(bootopt, NULL);
291 }
292 
293 /*
294  * kernel logging functions: log, logpri, addlog
295  */
296 
297 /*
298  * log: write to the log buffer
299  *
300  * => will not sleep [so safe to call from interrupt]
301  * => will log to console if /dev/klog isn't open
302  */
303 
304 void
305 log(int level, const char *fmt, ...)
306 {
307 	va_list ap;
308 
309 	kprintf_lock();
310 
311 	klogpri(level);		/* log the level first */
312 	va_start(ap, fmt);
313 	kprintf(fmt, TOLOG, NULL, NULL, ap);
314 	va_end(ap);
315 	if (!log_open) {
316 		va_start(ap, fmt);
317 		kprintf(fmt, TOCONS, NULL, NULL, ap);
318 		va_end(ap);
319 	}
320 
321 	kprintf_unlock();
322 
323 	logwakeup();		/* wake up anyone waiting for log msgs */
324 }
325 
326 /*
327  * vlog: write to the log buffer [already have va_list]
328  */
329 
330 void
331 vlog(int level, const char *fmt, va_list ap)
332 {
333 	va_list cap;
334 
335 	va_copy(cap, ap);
336 	kprintf_lock();
337 
338 	klogpri(level);		/* log the level first */
339 	kprintf(fmt, TOLOG, NULL, NULL, ap);
340 	if (!log_open)
341 		kprintf(fmt, TOCONS, NULL, NULL, cap);
342 
343 	kprintf_unlock();
344 	va_end(cap);
345 
346 	logwakeup();		/* wake up anyone waiting for log msgs */
347 }
348 
349 /*
350  * logpri: log the priority level to the klog
351  */
352 
353 void
354 logpri(int level)
355 {
356 
357 	kprintf_lock();
358 	klogpri(level);
359 	kprintf_unlock();
360 }
361 
362 /*
363  * Note: we must be in the mutex here!
364  */
365 void
366 klogpri(int level)
367 {
368 	KASSERT((level & KLOG_PRI) == 0);
369 
370 	putchar(level | KLOG_PRI, TOLOG, NULL);
371 }
372 
373 /*
374  * addlog: add info to previous log message
375  */
376 
377 void
378 addlog(const char *fmt, ...)
379 {
380 	va_list ap;
381 
382 	kprintf_lock();
383 
384 	va_start(ap, fmt);
385 	kprintf(fmt, TOLOG, NULL, NULL, ap);
386 	va_end(ap);
387 	if (!log_open) {
388 		va_start(ap, fmt);
389 		kprintf(fmt, TOCONS, NULL, NULL, ap);
390 		va_end(ap);
391 	}
392 
393 	kprintf_unlock();
394 
395 	logwakeup();
396 }
397 
398 static void
399 putone(int c, int flags, struct tty *tp)
400 {
401 	if (panicstr)
402 		constty = NULL;
403 
404 	if ((flags & TOCONS) && tp == NULL && constty) {
405 		tp = constty;
406 		flags |= TOTTY;
407 	}
408 	if ((flags & TOTTY) && tp &&
409 	    tputchar(c, flags, tp) < 0 &&
410 	    (flags & TOCONS) && tp == constty)
411 		constty = NULL;
412 	if ((flags & TOLOG) &&
413 	    c != '\0' && c != '\r' && c != 0177)
414 	    	logputchar(c);
415 	if ((flags & TOCONS) && constty == NULL && c != '\0')
416 		(*v_putc)(c);
417 }
418 
419 static void
420 putlogpri(int level)
421 {
422 	char *p;
423 	char snbuf[KPRINTF_BUFSIZE];
424 
425 	putone('<', TOLOG, NULL);
426 	snprintf(snbuf, sizeof(snbuf), "%d", level);
427 	for (p = snbuf ; *p ; p++)
428 		putone(*p, TOLOG, NULL);
429 	putone('>', TOLOG, NULL);
430 }
431 
432 #ifndef KLOG_NOTIMESTAMP
433 static int needtstamp = 1;
434 int log_ts_prec = 7;
435 
436 static void
437 addtstamp(int flags, struct tty *tp)
438 {
439 	char buf[64];
440 	struct timespec ts;
441 	int n, prec;
442 	long fsec;
443 
444 	prec = log_ts_prec;
445 	if (prec < 0) {
446 		prec = 0;
447 		log_ts_prec = prec;
448 	} else if (prec > 9) {
449 		prec = 9;
450 		log_ts_prec = prec;
451 	}
452 
453 	getnanouptime(&ts);
454 
455 	for (n = prec, fsec = ts.tv_nsec; n < 8; n++)
456 		fsec /= 10;
457 	if (n < 9)
458 		fsec = (fsec / 10) + ((fsec % 10) >= 5);
459 
460 	n = snprintf(buf, sizeof(buf), "[% 4jd.%.*ld] ",
461 	    (intmax_t)ts.tv_sec, prec, fsec);
462 
463 	for (int i = 0; i < n; i++)
464 		putone(buf[i], flags, tp);
465 }
466 #endif
467 
468 /*
469  * putchar: print a single character on console or user terminal.
470  *
471  * => if console, then the last MSGBUFS chars are saved in msgbuf
472  *	for inspection later (e.g. dmesg/syslog)
473  * => we must already be in the mutex!
474  */
475 static void
476 putchar(int c, int flags, struct tty *tp)
477 {
478 	if (c & KLOG_PRI) {
479 		putlogpri(c & ~KLOG_PRI);
480 		return;
481 	}
482 
483 #ifndef KLOG_NOTIMESTAMP
484 	if (c != '\0' && c != '\n' && needtstamp && (flags & NOTSTAMP) == 0) {
485 		addtstamp(flags, tp);
486 		needtstamp = 0;
487 	}
488 
489 	if (c == '\n')
490 		needtstamp = 1;
491 #endif
492 	putone(c, flags, tp);
493 
494 #ifdef DDB
495 	if (flags & TODDB) {
496 		db_putchar(c);
497 		return;
498 	}
499 #endif
500 
501 #ifdef RND_PRINTF
502 	if (__predict_true(kprintf_inited)) {
503 		unsigned char ch = c;
504 		rnd_add_data(&rnd_printf_source, &ch, 1, 0);
505 	}
506 #endif
507 }
508 
509 /*
510  * tablefull: warn that a system table is full
511  */
512 
513 void
514 tablefull(const char *tab, const char *hint)
515 {
516 	if (hint)
517 		log(LOG_ERR, "%s: table is full - %s\n", tab, hint);
518 	else
519 		log(LOG_ERR, "%s: table is full\n", tab);
520 }
521 
522 
523 /*
524  * uprintf: print to the controlling tty of the current process
525  *
526  * => we may block if the tty queue is full
527  * => no message is printed if the queue doesn't clear in a reasonable
528  *	time
529  */
530 
531 void
532 uprintf(const char *fmt, ...)
533 {
534 	struct proc *p = curproc;
535 	va_list ap;
536 
537 	/* mutex_enter(&proc_lock); XXXSMP */
538 
539 	if (p->p_lflag & PL_CONTROLT && p->p_session->s_ttyvp) {
540 		/* No mutex needed; going to process TTY. */
541 		va_start(ap, fmt);
542 		kprintf(fmt, TOTTY, p->p_session->s_ttyp, NULL, ap);
543 		va_end(ap);
544 	}
545 
546 	/* mutex_exit(&proc_lock); XXXSMP */
547 }
548 
549 void
550 uprintf_locked(const char *fmt, ...)
551 {
552 	struct proc *p = curproc;
553 	va_list ap;
554 
555 	if (p->p_lflag & PL_CONTROLT && p->p_session->s_ttyvp) {
556 		/* No mutex needed; going to process TTY. */
557 		va_start(ap, fmt);
558 		kprintf(fmt, TOTTY, p->p_session->s_ttyp, NULL, ap);
559 		va_end(ap);
560 	}
561 }
562 
563 /*
564  * tprintf functions: used to send messages to a specific process
565  *
566  * usage:
567  *   get a tpr_t handle on a process "p" by using "tprintf_open(p)"
568  *   use the handle when calling "tprintf"
569  *   when done, do a "tprintf_close" to drop the handle
570  */
571 
572 /*
573  * tprintf_open: get a tprintf handle on a process "p"
574  *
575  * => returns NULL if process can't be printed to
576  */
577 
578 tpr_t
579 tprintf_open(struct proc *p)
580 {
581 	tpr_t cookie;
582 
583 	cookie = NULL;
584 
585 	mutex_enter(&proc_lock);
586 	if (p->p_lflag & PL_CONTROLT && p->p_session->s_ttyvp) {
587 		proc_sesshold(p->p_session);
588 		cookie = (tpr_t)p->p_session;
589 	}
590 	mutex_exit(&proc_lock);
591 
592 	return cookie;
593 }
594 
595 /*
596  * tprintf_close: dispose of a tprintf handle obtained with tprintf_open
597  */
598 
599 void
600 tprintf_close(tpr_t sess)
601 {
602 
603 	if (sess) {
604 		mutex_enter(&proc_lock);
605 		/* Releases proc_lock. */
606 		proc_sessrele((struct session *)sess);
607 	}
608 }
609 
610 /*
611  * tprintf: given tprintf handle to a process [obtained with tprintf_open],
612  * send a message to the controlling tty for that process.
613  *
614  * => also sends message to /dev/klog
615  */
616 void
617 tprintf(tpr_t tpr, const char *fmt, ...)
618 {
619 	struct session *sess = (struct session *)tpr;
620 	struct tty *tp = NULL;
621 	int flags = TOLOG;
622 	va_list ap;
623 
624 	/* mutex_enter(&proc_lock); XXXSMP */
625 	if (sess && sess->s_ttyvp && ttycheckoutq(sess->s_ttyp, 0)) {
626 		flags |= TOTTY;
627 		tp = sess->s_ttyp;
628 	}
629 
630 	kprintf_lock();
631 
632 	klogpri(LOG_INFO);
633 	va_start(ap, fmt);
634 	kprintf(fmt, flags, tp, NULL, ap);
635 	va_end(ap);
636 
637 	kprintf_unlock();
638 	/* mutex_exit(&proc_lock);	XXXSMP */
639 
640 	logwakeup();
641 }
642 
643 
644 /*
645  * ttyprintf: send a message to a specific tty
646  *
647  * => should be used only by tty driver or anything that knows the
648  *    underlying tty will not be revoked(2)'d away.  [otherwise,
649  *    use tprintf]
650  */
651 void
652 ttyprintf(struct tty *tp, const char *fmt, ...)
653 {
654 	va_list ap;
655 
656 	/* No mutex needed; going to process TTY. */
657 	va_start(ap, fmt);
658 	kprintf(fmt, TOTTY, tp, NULL, ap);
659 	va_end(ap);
660 }
661 
662 #ifdef DDB
663 
664 /*
665  * db_printf: printf for DDB (via db_putchar)
666  */
667 
668 void
669 db_printf(const char *fmt, ...)
670 {
671 	va_list ap;
672 
673 	/* No mutex needed; DDB pauses all processors. */
674 	va_start(ap, fmt);
675 	kprintf(fmt, TODDB, NULL, NULL, ap);
676 	va_end(ap);
677 
678 	if (db_tee_msgbuf) {
679 		va_start(ap, fmt);
680 		kprintf(fmt, TOLOG, NULL, NULL, ap);
681 		va_end(ap);
682 	}
683 }
684 
685 void
686 db_vprintf(const char *fmt, va_list ap)
687 {
688 	va_list cap;
689 
690 	va_copy(cap, ap);
691 	/* No mutex needed; DDB pauses all processors. */
692 	kprintf(fmt, TODDB, NULL, NULL, ap);
693 	if (db_tee_msgbuf)
694 		kprintf(fmt, TOLOG, NULL, NULL, cap);
695 	va_end(cap);
696 }
697 
698 #endif /* DDB */
699 
700 static void
701 kprintf_internal(const char *fmt, int oflags, void *vp, char *sbuf, ...)
702 {
703 	va_list ap;
704 
705 	va_start(ap, sbuf);
706 	(void)kprintf(fmt, oflags, vp, sbuf, ap);
707 	va_end(ap);
708 }
709 
710 /*
711  * Device autoconfiguration printf routines.  These change their
712  * behavior based on the AB_* flags in boothowto.  If AB_SILENT
713  * is set, messages never go to the console (but they still always
714  * go to the log).  AB_VERBOSE overrides AB_SILENT.
715  */
716 
717 /*
718  * aprint_normal: Send to console unless AB_QUIET.  Always goes
719  * to the log.
720  */
721 static void
722 aprint_normal_internal(const char *prefix, const char *fmt, va_list ap)
723 {
724 	int flags = TOLOG;
725 
726 	if ((boothowto & (AB_SILENT|AB_QUIET)) == 0 ||
727 	    (boothowto & AB_VERBOSE) != 0)
728 		flags |= TOCONS;
729 
730 	kprintf_lock();
731 
732 	if (prefix)
733 		kprintf_internal("%s: ", flags, NULL, NULL, prefix);
734 	kprintf(fmt, flags, NULL, NULL, ap);
735 
736 	kprintf_unlock();
737 
738 	if (!panicstr)
739 		logwakeup();
740 }
741 
742 void
743 aprint_normal(const char *fmt, ...)
744 {
745 	va_list ap;
746 
747 	va_start(ap, fmt);
748 	aprint_normal_internal(NULL, fmt, ap);
749 	va_end(ap);
750 }
751 
752 void
753 aprint_normal_dev(device_t dv, const char *fmt, ...)
754 {
755 	va_list ap;
756 
757 	KASSERT(dv != NULL);
758 
759 	va_start(ap, fmt);
760 	aprint_normal_internal(device_xname(dv), fmt, ap);
761 	va_end(ap);
762 }
763 
764 void
765 aprint_normal_ifnet(struct ifnet *ifp, const char *fmt, ...)
766 {
767 	va_list ap;
768 
769 	KASSERT(ifp != NULL);
770 
771 	va_start(ap, fmt);
772 	aprint_normal_internal(ifp->if_xname, fmt, ap);
773 	va_end(ap);
774 }
775 
776 /*
777  * aprint_error: Send to console unless AB_QUIET.  Always goes
778  * to the log.  Also counts the number of times called so other
779  * parts of the kernel can report the number of errors during a
780  * given phase of system startup.
781  */
782 static int aprint_error_count;
783 
784 int
785 aprint_get_error_count(void)
786 {
787 	int count;
788 
789 	kprintf_lock();
790 
791 	count = aprint_error_count;
792 	aprint_error_count = 0;
793 
794 	kprintf_unlock();
795 
796 	return (count);
797 }
798 
799 static void
800 aprint_error_internal(const char *prefix, const char *fmt, va_list ap)
801 {
802 	int flags = TOLOG;
803 
804 	if ((boothowto & (AB_SILENT|AB_QUIET)) == 0 ||
805 	    (boothowto & AB_VERBOSE) != 0)
806 		flags |= TOCONS;
807 
808 	kprintf_lock();
809 
810 	aprint_error_count++;
811 
812 	if (prefix)
813 		kprintf_internal("%s: ", flags, NULL, NULL, prefix);
814 	kprintf_internal("autoconfiguration error: ", TOLOG, NULL, NULL);
815 	kprintf(fmt, flags, NULL, NULL, ap);
816 
817 	kprintf_unlock();
818 
819 	if (!panicstr)
820 		logwakeup();
821 }
822 
823 void
824 aprint_error(const char *fmt, ...)
825 {
826 	va_list ap;
827 
828 	va_start(ap, fmt);
829 	aprint_error_internal(NULL, fmt, ap);
830 	va_end(ap);
831 }
832 
833 void
834 aprint_error_dev(device_t dv, const char *fmt, ...)
835 {
836 	va_list ap;
837 
838 	KASSERT(dv != NULL);
839 
840 	va_start(ap, fmt);
841 	aprint_error_internal(device_xname(dv), fmt, ap);
842 	va_end(ap);
843 }
844 
845 void
846 aprint_error_ifnet(struct ifnet *ifp, const char *fmt, ...)
847 {
848 	va_list ap;
849 
850 	KASSERT(ifp != NULL);
851 
852 	va_start(ap, fmt);
853 	aprint_error_internal(ifp->if_xname, fmt, ap);
854 	va_end(ap);
855 }
856 
857 /*
858  * aprint_naive: Send to console only if AB_QUIET.  Never goes
859  * to the log.
860  */
861 static void
862 aprint_naive_internal(const char *prefix, const char *fmt, va_list ap)
863 {
864 	if ((boothowto & (AB_QUIET|AB_SILENT|AB_VERBOSE)) != AB_QUIET)
865 		return;
866 
867 	kprintf_lock();
868 
869 	if (prefix)
870 		kprintf_internal("%s: ", TOCONS, NULL, NULL, prefix);
871 	kprintf(fmt, TOCONS, NULL, NULL, ap);
872 
873 	kprintf_unlock();
874 }
875 
876 void
877 aprint_naive(const char *fmt, ...)
878 {
879 	va_list ap;
880 
881 	va_start(ap, fmt);
882 	aprint_naive_internal(NULL, fmt, ap);
883 	va_end(ap);
884 }
885 
886 void
887 aprint_naive_dev(device_t dv, const char *fmt, ...)
888 {
889 	va_list ap;
890 
891 	KASSERT(dv != NULL);
892 
893 	va_start(ap, fmt);
894 	aprint_naive_internal(device_xname(dv), fmt, ap);
895 	va_end(ap);
896 }
897 
898 void
899 aprint_naive_ifnet(struct ifnet *ifp, const char *fmt, ...)
900 {
901 	va_list ap;
902 
903 	KASSERT(ifp != NULL);
904 
905 	va_start(ap, fmt);
906 	aprint_naive_internal(ifp->if_xname, fmt, ap);
907 	va_end(ap);
908 }
909 
910 /*
911  * aprint_verbose: Send to console only if AB_VERBOSE.  Always
912  * goes to the log.
913  */
914 static void
915 aprint_verbose_internal(const char *prefix, const char *fmt, va_list ap)
916 {
917 	int flags = TOLOG;
918 
919 	if (boothowto & AB_VERBOSE)
920 		flags |= TOCONS;
921 
922 	kprintf_lock();
923 
924 	if (prefix)
925 		kprintf_internal("%s: ", flags, NULL, NULL, prefix);
926 	kprintf(fmt, flags, NULL, NULL, ap);
927 
928 	kprintf_unlock();
929 
930 	if (!panicstr)
931 		logwakeup();
932 }
933 
934 void
935 aprint_verbose(const char *fmt, ...)
936 {
937 	va_list ap;
938 
939 	va_start(ap, fmt);
940 	aprint_verbose_internal(NULL, fmt, ap);
941 	va_end(ap);
942 }
943 
944 void
945 aprint_verbose_dev(device_t dv, const char *fmt, ...)
946 {
947 	va_list ap;
948 
949 	KASSERT(dv != NULL);
950 
951 	va_start(ap, fmt);
952 	aprint_verbose_internal(device_xname(dv), fmt, ap);
953 	va_end(ap);
954 }
955 
956 void
957 aprint_verbose_ifnet(struct ifnet *ifp, const char *fmt, ...)
958 {
959 	va_list ap;
960 
961 	KASSERT(ifp != NULL);
962 
963 	va_start(ap, fmt);
964 	aprint_verbose_internal(ifp->if_xname, fmt, ap);
965 	va_end(ap);
966 }
967 
968 /*
969  * aprint_debug: Send to console and log only if AB_DEBUG.
970  */
971 static void
972 aprint_debug_internal(const char *prefix, const char *fmt, va_list ap)
973 {
974 	if ((boothowto & AB_DEBUG) == 0)
975 		return;
976 
977 	kprintf_lock();
978 
979 	if (prefix)
980 		kprintf_internal("%s: ", TOCONS | TOLOG, NULL, NULL, prefix);
981 	kprintf(fmt, TOCONS | TOLOG, NULL, NULL, ap);
982 
983 	kprintf_unlock();
984 }
985 
986 void
987 aprint_debug(const char *fmt, ...)
988 {
989 	va_list ap;
990 
991 	va_start(ap, fmt);
992 	aprint_debug_internal(NULL, fmt, ap);
993 	va_end(ap);
994 }
995 
996 void
997 aprint_debug_dev(device_t dv, const char *fmt, ...)
998 {
999 	va_list ap;
1000 
1001 	KASSERT(dv != NULL);
1002 
1003 	va_start(ap, fmt);
1004 	aprint_debug_internal(device_xname(dv), fmt, ap);
1005 	va_end(ap);
1006 }
1007 
1008 void
1009 aprint_debug_ifnet(struct ifnet *ifp, const char *fmt, ...)
1010 {
1011 	va_list ap;
1012 
1013 	KASSERT(ifp != NULL);
1014 
1015 	va_start(ap, fmt);
1016 	aprint_debug_internal(ifp->if_xname, fmt, ap);
1017 	va_end(ap);
1018 }
1019 
1020 void
1021 vprintf_flags(int flags, const char *fmt, va_list ap)
1022 {
1023 	kprintf_lock();
1024 	kprintf(fmt, flags, NULL, NULL, ap);
1025 	kprintf_unlock();
1026 }
1027 
1028 void
1029 printf_flags(int flags, const char *fmt, ...)
1030 {
1031 	va_list ap;
1032 
1033 	va_start(ap, fmt);
1034 	vprintf_flags(flags, fmt, ap);
1035 	va_end(ap);
1036 }
1037 
1038 void
1039 printf_tolog(const char *fmt, ...)
1040 {
1041 	va_list ap;
1042 
1043 	va_start(ap, fmt);
1044 	vprintf_flags(TOLOG, fmt, ap);
1045 	va_end(ap);
1046 }
1047 
1048 /*
1049  * printf_nolog: Like printf(), but does not send message to the log.
1050  */
1051 
1052 void
1053 printf_nolog(const char *fmt, ...)
1054 {
1055 	va_list ap;
1056 
1057 	va_start(ap, fmt);
1058 	vprintf_flags(TOCONS, fmt, ap);
1059 	va_end(ap);
1060 }
1061 
1062 /*
1063  * printf_nostamp: Like printf(), but does not prepend a timestamp.
1064  */
1065 
1066 void
1067 printf_nostamp(const char *fmt, ...)
1068 {
1069 	va_list ap;
1070 
1071 	va_start(ap, fmt);
1072 	vprintf_flags(TOCONS|NOTSTAMP, fmt, ap);
1073 	va_end(ap);
1074 }
1075 
1076 /*
1077  * normal kernel printf functions: printf, vprintf, snprintf, vsnprintf
1078  */
1079 
1080 /*
1081  * printf: print a message to the console and the log
1082  */
1083 void
1084 printf(const char *fmt, ...)
1085 {
1086 	va_list ap;
1087 
1088 	va_start(ap, fmt);
1089 	vprintf_flags(TOCONS | TOLOG, fmt, ap);
1090 	va_end(ap);
1091 }
1092 
1093 /*
1094  * vprintf: print a message to the console and the log [already have
1095  *	va_list]
1096  */
1097 
1098 void
1099 vprintf(const char *fmt, va_list ap)
1100 {
1101 	vprintf_flags(TOCONS | TOLOG, fmt, ap);
1102 
1103 	if (!panicstr)
1104 		logwakeup();
1105 }
1106 
1107 /*
1108  * snprintf: print a message to a buffer
1109  */
1110 int
1111 snprintf(char *bf, size_t size, const char *fmt, ...)
1112 {
1113 	int retval;
1114 	va_list ap;
1115 
1116 	va_start(ap, fmt);
1117 	retval = vsnprintf(bf, size, fmt, ap);
1118 	va_end(ap);
1119 
1120 	return retval;
1121 }
1122 
1123 /*
1124  * vsnprintf: print a message to a buffer [already have va_list]
1125  */
1126 int
1127 vsnprintf(char *bf, size_t size, const char *fmt, va_list ap)
1128 {
1129 	int retval;
1130 	char *p;
1131 
1132 	p = bf + size;
1133 	retval = kprintf(fmt, TOBUFONLY, &p, bf, ap);
1134 	if (bf && size > 0) {
1135 		/* nul terminate */
1136 		if (size <= (size_t)retval)
1137 			bf[size - 1] = '\0';
1138 		else
1139 			bf[retval] = '\0';
1140 	}
1141 	return retval;
1142 }
1143 
1144 int
1145 vasprintf(char **bf, const char *fmt, va_list ap)
1146 {
1147 	int retval;
1148 	va_list cap;
1149 
1150 	va_copy(cap, ap);
1151 	retval = kprintf(fmt, TOBUFONLY, NULL, NULL, cap) + 1;
1152 	va_end(cap);
1153 	*bf = kmem_alloc(retval, KM_SLEEP);
1154 	return vsnprintf(*bf, retval, fmt, ap);
1155 }
1156 
1157 /*
1158  * kprintf: scaled down version of printf(3).
1159  *
1160  * this version based on vfprintf() from libc which was derived from
1161  * software contributed to Berkeley by Chris Torek.
1162  *
1163  * NOTE: The kprintf mutex must be held if we're going TOBUF or TOCONS!
1164  */
1165 
1166 /*
1167  * macros for converting digits to letters and vice versa
1168  */
1169 #define	to_digit(c)	((c) - '0')
1170 #define is_digit(c)	((unsigned)to_digit(c) <= 9)
1171 #define	to_char(n)	((n) + '0')
1172 
1173 /*
1174  * flags used during conversion.
1175  */
1176 #define	ALT		0x001		/* alternate form */
1177 #define	HEXPREFIX	0x002		/* add 0x or 0X prefix */
1178 #define	LADJUST		0x004		/* left adjustment */
1179 #define	LONGDBL		0x008		/* long double; unimplemented */
1180 #define	LONGINT		0x010		/* long integer */
1181 #define	QUADINT		0x020		/* quad integer */
1182 #define	SHORTINT	0x040		/* short integer */
1183 #define	MAXINT		0x080		/* intmax_t */
1184 #define	PTRINT		0x100		/* intptr_t */
1185 #define	SIZEINT		0x200		/* size_t */
1186 #define	ZEROPAD		0x400		/* zero (as opposed to blank) pad */
1187 #define FPT		0x800		/* Floating point number */
1188 
1189 	/*
1190 	 * To extend shorts properly, we need both signed and unsigned
1191 	 * argument extraction methods.
1192 	 */
1193 #define	SARG() \
1194 	(flags&MAXINT ? va_arg(ap, intmax_t) : \
1195 	    flags&PTRINT ? va_arg(ap, intptr_t) : \
1196 	    flags&SIZEINT ? va_arg(ap, ssize_t) : /* XXX */ \
1197 	    flags&QUADINT ? va_arg(ap, quad_t) : \
1198 	    flags&LONGINT ? va_arg(ap, long) : \
1199 	    flags&SHORTINT ? (long)(short)va_arg(ap, int) : \
1200 	    (long)va_arg(ap, int))
1201 #define	UARG() \
1202 	(flags&MAXINT ? va_arg(ap, uintmax_t) : \
1203 	    flags&PTRINT ? va_arg(ap, uintptr_t) : \
1204 	    flags&SIZEINT ? va_arg(ap, size_t) : \
1205 	    flags&QUADINT ? va_arg(ap, u_quad_t) : \
1206 	    flags&LONGINT ? va_arg(ap, u_long) : \
1207 	    flags&SHORTINT ? (u_long)(u_short)va_arg(ap, int) : \
1208 	    (u_long)va_arg(ap, u_int))
1209 
1210 #define KPRINTF_PUTCHAR(C) {						\
1211 	if (oflags == TOBUFONLY) {					\
1212 		if (sbuf && ((vp == NULL) || (sbuf < tailp))) 		\
1213 			*sbuf++ = (C);					\
1214 	} else {							\
1215 		putchar((C), oflags, vp);				\
1216 	}								\
1217 }
1218 
1219 void
1220 device_printf(device_t dev, const char *fmt, ...)
1221 {
1222 	va_list ap;
1223 
1224 	va_start(ap, fmt);
1225 	printf("%s: ", device_xname(dev));
1226 	vprintf(fmt, ap);
1227 	va_end(ap);
1228 	return;
1229 }
1230 
1231 /*
1232  * Guts of kernel printf.  Note, we already expect to be in a mutex!
1233  */
1234 int
1235 kprintf(const char *fmt0, int oflags, void *vp, char *sbuf, va_list ap)
1236 {
1237 	const char *fmt;	/* format string */
1238 	int ch;			/* character from fmt */
1239 	int n;			/* handy integer (short term usage) */
1240 	char *cp;		/* handy char pointer (short term usage) */
1241 	int flags;		/* flags as above */
1242 	int ret;		/* return value accumulator */
1243 	int width;		/* width from format (%8d), or 0 */
1244 	int prec;		/* precision from format (%.3d), or -1 */
1245 	char sign;		/* sign prefix (' ', '+', '-', or \0) */
1246 
1247 	u_quad_t _uquad;	/* integer arguments %[diouxX] */
1248 	enum { OCT, DEC, HEX } base;/* base for [diouxX] conversion */
1249 	int dprec;		/* a copy of prec if [diouxX], 0 otherwise */
1250 	int realsz;		/* field size expanded by dprec */
1251 	int size;		/* size of converted field or string */
1252 	const char *xdigs;	/* digits for [xX] conversion */
1253 	char bf[KPRINTF_BUFSIZE]; /* space for %c, %[diouxX] */
1254 	char *tailp;		/* tail pointer for snprintf */
1255 
1256 	if (oflags == TOBUFONLY && (vp != NULL))
1257 		tailp = *(char **)vp;
1258 	else
1259 		tailp = NULL;
1260 
1261 	cp = NULL;	/* XXX: shutup gcc */
1262 	size = 0;	/* XXX: shutup gcc */
1263 
1264 	fmt = fmt0;
1265 	ret = 0;
1266 
1267 	xdigs = NULL;		/* XXX: shut up gcc warning */
1268 
1269 	/*
1270 	 * Scan the format for conversions (`%' character).
1271 	 */
1272 	for (;;) {
1273 		for (; *fmt != '%' && *fmt; fmt++) {
1274 			ret++;
1275 			KPRINTF_PUTCHAR(*fmt);
1276 		}
1277 		if (*fmt == 0)
1278 			goto done;
1279 
1280 		fmt++;		/* skip over '%' */
1281 
1282 		flags = 0;
1283 		dprec = 0;
1284 		width = 0;
1285 		prec = -1;
1286 		sign = '\0';
1287 
1288 rflag:		ch = *fmt++;
1289 reswitch:	switch (ch) {
1290 		case ' ':
1291 			/*
1292 			 * ``If the space and + flags both appear, the space
1293 			 * flag will be ignored.''
1294 			 *	-- ANSI X3J11
1295 			 */
1296 			if (!sign)
1297 				sign = ' ';
1298 			goto rflag;
1299 		case '#':
1300 			flags |= ALT;
1301 			goto rflag;
1302 		case '*':
1303 			/*
1304 			 * ``A negative field width argument is taken as a
1305 			 * - flag followed by a positive field width.''
1306 			 *	-- ANSI X3J11
1307 			 * They don't exclude field widths read from args.
1308 			 */
1309 			if ((width = va_arg(ap, int)) >= 0)
1310 				goto rflag;
1311 			width = -width;
1312 			/* FALLTHROUGH */
1313 		case '-':
1314 			flags |= LADJUST;
1315 			goto rflag;
1316 		case '+':
1317 			sign = '+';
1318 			goto rflag;
1319 		case '.':
1320 			if ((ch = *fmt++) == '*') {
1321 				n = va_arg(ap, int);
1322 				prec = n < 0 ? -1 : n;
1323 				goto rflag;
1324 			}
1325 			n = 0;
1326 			while (is_digit(ch)) {
1327 				n = 10 * n + to_digit(ch);
1328 				ch = *fmt++;
1329 			}
1330 			prec = n < 0 ? -1 : n;
1331 			goto reswitch;
1332 		case '0':
1333 			/*
1334 			 * ``Note that 0 is taken as a flag, not as the
1335 			 * beginning of a field width.''
1336 			 *	-- ANSI X3J11
1337 			 */
1338 			flags |= ZEROPAD;
1339 			goto rflag;
1340 		case '1': case '2': case '3': case '4':
1341 		case '5': case '6': case '7': case '8': case '9':
1342 			n = 0;
1343 			do {
1344 				n = 10 * n + to_digit(ch);
1345 				ch = *fmt++;
1346 			} while (is_digit(ch));
1347 			width = n;
1348 			goto reswitch;
1349 		case 'h':
1350 			flags |= SHORTINT;
1351 			goto rflag;
1352 		case 'j':
1353 			flags |= MAXINT;
1354 			goto rflag;
1355 		case 'l':
1356 			if (*fmt == 'l') {
1357 				fmt++;
1358 				flags |= QUADINT;
1359 			} else {
1360 				flags |= LONGINT;
1361 			}
1362 			goto rflag;
1363 		case 'q':
1364 			flags |= QUADINT;
1365 			goto rflag;
1366 		case 't':
1367 			flags |= PTRINT;
1368 			goto rflag;
1369 		case 'z':
1370 			flags |= SIZEINT;
1371 			goto rflag;
1372 		case 'c':
1373 			*(cp = bf) = va_arg(ap, int);
1374 			size = 1;
1375 			sign = '\0';
1376 			break;
1377 		case 'D':
1378 			flags |= LONGINT;
1379 			/*FALLTHROUGH*/
1380 		case 'd':
1381 		case 'i':
1382 			_uquad = SARG();
1383 			if ((quad_t)_uquad < 0) {
1384 				_uquad = -_uquad;
1385 				sign = '-';
1386 			}
1387 			base = DEC;
1388 			goto number;
1389 		case 'n':
1390 			/* no %n support in the kernel, consume and skip */
1391 			if (flags & MAXINT)
1392 				(void)va_arg(ap, intmax_t *);
1393 			else if (flags & PTRINT)
1394 				(void)va_arg(ap, intptr_t *);
1395 			else if (flags & SIZEINT)
1396 				(void)va_arg(ap, ssize_t *);
1397 			else if (flags & QUADINT)
1398 				(void)va_arg(ap, quad_t *);
1399 			else if (flags & LONGINT)
1400 				(void)va_arg(ap, long *);
1401 			else if (flags & SHORTINT)
1402 				(void)va_arg(ap, short *);
1403 			else
1404 				(void)va_arg(ap, int *);
1405 			continue;	/* no output */
1406 		case 'O':
1407 			flags |= LONGINT;
1408 			/*FALLTHROUGH*/
1409 		case 'o':
1410 			_uquad = UARG();
1411 			base = OCT;
1412 			goto nosign;
1413 		case 'p':
1414 			/*
1415 			 * ``The argument shall be a pointer to void.  The
1416 			 * value of the pointer is converted to a sequence
1417 			 * of printable characters, in an implementation-
1418 			 * defined manner.''
1419 			 *	-- ANSI X3J11
1420 			 */
1421 			/* NOSTRICT */
1422 			_uquad = (u_long)va_arg(ap, void *);
1423 			base = HEX;
1424 			xdigs = hexdigits;
1425 			flags |= HEXPREFIX;
1426 			ch = 'x';
1427 			goto nosign;
1428 		case 's':
1429 			if ((cp = va_arg(ap, char *)) == NULL)
1430 				/*XXXUNCONST*/
1431 				cp = __UNCONST("(null)");
1432 			if (prec >= 0) {
1433 				/*
1434 				 * can't use strlen; can only look for the
1435 				 * NUL in the first `prec' characters, and
1436 				 * strlen() will go further.
1437 				 */
1438 				char *p = memchr(cp, 0, prec);
1439 
1440 				if (p != NULL) {
1441 					size = p - cp;
1442 					if (size > prec)
1443 						size = prec;
1444 				} else
1445 					size = prec;
1446 			} else
1447 				size = strlen(cp);
1448 			sign = '\0';
1449 			break;
1450 		case 'U':
1451 			flags |= LONGINT;
1452 			/*FALLTHROUGH*/
1453 		case 'u':
1454 			_uquad = UARG();
1455 			base = DEC;
1456 			goto nosign;
1457 		case 'X':
1458 			xdigs = HEXDIGITS;
1459 			goto hex;
1460 		case 'x':
1461 			xdigs = hexdigits;
1462 hex:			_uquad = UARG();
1463 			base = HEX;
1464 			/* leading 0x/X only if non-zero */
1465 			if (flags & ALT && _uquad != 0)
1466 				flags |= HEXPREFIX;
1467 
1468 			/* unsigned conversions */
1469 nosign:			sign = '\0';
1470 			/*
1471 			 * ``... diouXx conversions ... if a precision is
1472 			 * specified, the 0 flag will be ignored.''
1473 			 *	-- ANSI X3J11
1474 			 */
1475 number:			if ((dprec = prec) >= 0)
1476 				flags &= ~ZEROPAD;
1477 
1478 			/*
1479 			 * ``The result of converting a zero value with an
1480 			 * explicit precision of zero is no characters.''
1481 			 *	-- ANSI X3J11
1482 			 */
1483 			cp = bf + KPRINTF_BUFSIZE;
1484 			if (_uquad != 0 || prec != 0) {
1485 				/*
1486 				 * Unsigned mod is hard, and unsigned mod
1487 				 * by a constant is easier than that by
1488 				 * a variable; hence this switch.
1489 				 */
1490 				switch (base) {
1491 				case OCT:
1492 					do {
1493 						*--cp = to_char(_uquad & 7);
1494 						_uquad >>= 3;
1495 					} while (_uquad);
1496 					/* handle octal leading 0 */
1497 					if (flags & ALT && *cp != '0')
1498 						*--cp = '0';
1499 					break;
1500 
1501 				case DEC:
1502 					/* many numbers are 1 digit */
1503 					while (_uquad >= 10) {
1504 						*--cp = to_char(_uquad % 10);
1505 						_uquad /= 10;
1506 					}
1507 					*--cp = to_char(_uquad);
1508 					break;
1509 
1510 				case HEX:
1511 					do {
1512 						*--cp = xdigs[_uquad & 15];
1513 						_uquad >>= 4;
1514 					} while (_uquad);
1515 					break;
1516 
1517 				default:
1518 					/*XXXUNCONST*/
1519 					cp = __UNCONST("bug in kprintf: bad base");
1520 					size = strlen(cp);
1521 					goto skipsize;
1522 				}
1523 			}
1524 			size = bf + KPRINTF_BUFSIZE - cp;
1525 		skipsize:
1526 			break;
1527 		default:	/* "%?" prints ?, unless ? is NUL */
1528 			if (ch == '\0')
1529 				goto done;
1530 			/* pretend it was %c with argument ch */
1531 			cp = bf;
1532 			*cp = ch;
1533 			size = 1;
1534 			sign = '\0';
1535 			break;
1536 		}
1537 
1538 		/*
1539 		 * All reasonable formats wind up here.  At this point, `cp'
1540 		 * points to a string which (if not flags&LADJUST) should be
1541 		 * padded out to `width' places.  If flags&ZEROPAD, it should
1542 		 * first be prefixed by any sign or other prefix; otherwise,
1543 		 * it should be blank padded before the prefix is emitted.
1544 		 * After any left-hand padding and prefixing, emit zeroes
1545 		 * required by a decimal [diouxX] precision, then print the
1546 		 * string proper, then emit zeroes required by any leftover
1547 		 * floating precision; finally, if LADJUST, pad with blanks.
1548 		 *
1549 		 * Compute actual size, so we know how much to pad.
1550 		 * size excludes decimal prec; realsz includes it.
1551 		 */
1552 		realsz = dprec > size ? dprec : size;
1553 		if (sign)
1554 			realsz++;
1555 		else if (flags & HEXPREFIX)
1556 			realsz+= 2;
1557 
1558 		/* adjust ret */
1559 		ret += width > realsz ? width : realsz;
1560 
1561 		/* right-adjusting blank padding */
1562 		if ((flags & (LADJUST|ZEROPAD)) == 0) {
1563 			n = width - realsz;
1564 			while (n-- > 0)
1565 				KPRINTF_PUTCHAR(' ');
1566 		}
1567 
1568 		/* prefix */
1569 		if (sign) {
1570 			KPRINTF_PUTCHAR(sign);
1571 		} else if (flags & HEXPREFIX) {
1572 			KPRINTF_PUTCHAR('0');
1573 			KPRINTF_PUTCHAR(ch);
1574 		}
1575 
1576 		/* right-adjusting zero padding */
1577 		if ((flags & (LADJUST|ZEROPAD)) == ZEROPAD) {
1578 			n = width - realsz;
1579 			while (n-- > 0)
1580 				KPRINTF_PUTCHAR('0');
1581 		}
1582 
1583 		/* leading zeroes from decimal precision */
1584 		n = dprec - size;
1585 		while (n-- > 0)
1586 			KPRINTF_PUTCHAR('0');
1587 
1588 		/* the string or number proper */
1589 		for (; size--; cp++)
1590 			KPRINTF_PUTCHAR(*cp);
1591 		/* left-adjusting padding (always blank) */
1592 		if (flags & LADJUST) {
1593 			n = width - realsz;
1594 			while (n-- > 0)
1595 				KPRINTF_PUTCHAR(' ');
1596 		}
1597 	}
1598 
1599 done:
1600 	if ((oflags == TOBUFONLY) && (vp != NULL))
1601 		*(char **)vp = sbuf;
1602 	(*v_flush)();
1603 
1604 #ifdef RND_PRINTF
1605 	if (__predict_true(kprintf_inited))
1606 		rnd_add_data(&rnd_printf_source, NULL, 0, 0);
1607 #endif
1608 	return ret;
1609 }
1610