subr_sbuf.c revision 288484 
1/*-
2 * Copyright (c) 2000-2008 Poul-Henning Kamp
3 * Copyright (c) 2000-2008 Dag-Erling Co��dan Sm��rgrav
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer
11 *    in this position and unchanged.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD: head/sys/kern/subr_sbuf.c 288484 2015-10-02 09:23:14Z phk $");
31
32#include <sys/param.h>
33
34#ifdef _KERNEL
35#include <sys/ctype.h>
36#include <sys/errno.h>
37#include <sys/kernel.h>
38#include <sys/limits.h>
39#include <sys/malloc.h>
40#include <sys/systm.h>
41#include <sys/uio.h>
42#include <machine/stdarg.h>
43#else /* _KERNEL */
44#include <ctype.h>
45#include <errno.h>
46#include <limits.h>
47#include <stdarg.h>
48#include <stdio.h>
49#include <stdlib.h>
50#include <string.h>
51#endif /* _KERNEL */
52
53#include <sys/sbuf.h>
54
55#ifdef _KERNEL
56static MALLOC_DEFINE(M_SBUF, "sbuf", "string buffers");
57#define	SBMALLOC(size)		malloc(size, M_SBUF, M_WAITOK|M_ZERO)
58#define	SBFREE(buf)		free(buf, M_SBUF)
59#else /* _KERNEL */
60#define	KASSERT(e, m)
61#define	SBMALLOC(size)		calloc(1, size)
62#define	SBFREE(buf)		free(buf)
63#endif /* _KERNEL */
64
65/*
66 * Predicates
67 */
68#define	SBUF_ISDYNAMIC(s)	((s)->s_flags & SBUF_DYNAMIC)
69#define	SBUF_ISDYNSTRUCT(s)	((s)->s_flags & SBUF_DYNSTRUCT)
70#define	SBUF_ISFINISHED(s)	((s)->s_flags & SBUF_FINISHED)
71#define	SBUF_HASROOM(s)		((s)->s_len < (s)->s_size - 1)
72#define	SBUF_FREESPACE(s)	((s)->s_size - ((s)->s_len + 1))
73#define	SBUF_CANEXTEND(s)	((s)->s_flags & SBUF_AUTOEXTEND)
74#define	SBUF_ISSECTION(s)	((s)->s_flags & SBUF_INSECTION)
75#define	SBUF_NULINCLUDED(s)	((s)->s_flags & SBUF_INCLUDENUL)
76
77/*
78 * Set / clear flags
79 */
80#define	SBUF_SETFLAG(s, f)	do { (s)->s_flags |= (f); } while (0)
81#define	SBUF_CLEARFLAG(s, f)	do { (s)->s_flags &= ~(f); } while (0)
82
83#define	SBUF_MINSIZE		 2		/* Min is 1 byte + nulterm. */
84#define	SBUF_MINEXTENDSIZE	16		/* Should be power of 2. */
85
86#ifdef PAGE_SIZE
87#define	SBUF_MAXEXTENDSIZE	PAGE_SIZE
88#define	SBUF_MAXEXTENDINCR	PAGE_SIZE
89#else
90#define	SBUF_MAXEXTENDSIZE	4096
91#define	SBUF_MAXEXTENDINCR	4096
92#endif
93
94/*
95 * Debugging support
96 */
97#if defined(_KERNEL) && defined(INVARIANTS)
98
99static void
100_assert_sbuf_integrity(const char *fun, struct sbuf *s)
101{
102
103	KASSERT(s != NULL,
104	    ("%s called with a NULL sbuf pointer", fun));
105	KASSERT(s->s_buf != NULL,
106	    ("%s called with uninitialized or corrupt sbuf", fun));
107        if (SBUF_ISFINISHED(s) && SBUF_NULINCLUDED(s)) {
108		KASSERT(s->s_len <= s->s_size,
109		    ("wrote past end of sbuf (%jd >= %jd)",
110		    (intmax_t)s->s_len, (intmax_t)s->s_size));
111	} else {
112		KASSERT(s->s_len < s->s_size,
113		    ("wrote past end of sbuf (%jd >= %jd)",
114		    (intmax_t)s->s_len, (intmax_t)s->s_size));
115	}
116}
117
118static void
119_assert_sbuf_state(const char *fun, struct sbuf *s, int state)
120{
121
122	KASSERT((s->s_flags & SBUF_FINISHED) == state,
123	    ("%s called with %sfinished or corrupt sbuf", fun,
124	    (state ? "un" : "")));
125}
126
127#define	assert_sbuf_integrity(s) _assert_sbuf_integrity(__func__, (s))
128#define	assert_sbuf_state(s, i)	 _assert_sbuf_state(__func__, (s), (i))
129
130#else /* _KERNEL && INVARIANTS */
131
132#define	assert_sbuf_integrity(s) do { } while (0)
133#define	assert_sbuf_state(s, i)	 do { } while (0)
134
135#endif /* _KERNEL && INVARIANTS */
136
137#ifdef CTASSERT
138CTASSERT(powerof2(SBUF_MAXEXTENDSIZE));
139CTASSERT(powerof2(SBUF_MAXEXTENDINCR));
140#endif
141
142static int
143sbuf_extendsize(int size)
144{
145	int newsize;
146
147	if (size < (int)SBUF_MAXEXTENDSIZE) {
148		newsize = SBUF_MINEXTENDSIZE;
149		while (newsize < size)
150			newsize *= 2;
151	} else {
152		newsize = roundup2(size, SBUF_MAXEXTENDINCR);
153	}
154	KASSERT(newsize >= size, ("%s: %d < %d\n", __func__, newsize, size));
155	return (newsize);
156}
157
158/*
159 * Extend an sbuf.
160 */
161static int
162sbuf_extend(struct sbuf *s, int addlen)
163{
164	char *newbuf;
165	int newsize;
166
167	if (!SBUF_CANEXTEND(s))
168		return (-1);
169	newsize = sbuf_extendsize(s->s_size + addlen);
170	newbuf = SBMALLOC(newsize);
171	if (newbuf == NULL)
172		return (-1);
173	memcpy(newbuf, s->s_buf, s->s_size);
174	if (SBUF_ISDYNAMIC(s))
175		SBFREE(s->s_buf);
176	else
177		SBUF_SETFLAG(s, SBUF_DYNAMIC);
178	s->s_buf = newbuf;
179	s->s_size = newsize;
180	return (0);
181}
182
183/*
184 * Initialize the internals of an sbuf.
185 * If buf is non-NULL, it points to a static or already-allocated string
186 * big enough to hold at least length characters.
187 */
188static struct sbuf *
189sbuf_newbuf(struct sbuf *s, char *buf, int length, int flags)
190{
191
192	memset(s, 0, sizeof(*s));
193	s->s_flags = flags;
194	s->s_size = length;
195	s->s_buf = buf;
196
197	if ((s->s_flags & SBUF_AUTOEXTEND) == 0) {
198		KASSERT(s->s_size >= SBUF_MINSIZE,
199		    ("attempt to create an sbuf smaller than %d bytes",
200		    SBUF_MINSIZE));
201	}
202
203	if (s->s_buf != NULL)
204		return (s);
205
206	if ((flags & SBUF_AUTOEXTEND) != 0)
207		s->s_size = sbuf_extendsize(s->s_size);
208
209	s->s_buf = SBMALLOC(s->s_size);
210	if (s->s_buf == NULL)
211		return (NULL);
212	SBUF_SETFLAG(s, SBUF_DYNAMIC);
213	return (s);
214}
215
216/*
217 * Initialize an sbuf.
218 * If buf is non-NULL, it points to a static or already-allocated string
219 * big enough to hold at least length characters.
220 */
221struct sbuf *
222sbuf_new(struct sbuf *s, char *buf, int length, int flags)
223{
224
225	KASSERT(length >= 0,
226	    ("attempt to create an sbuf of negative length (%d)", length));
227	KASSERT((flags & ~SBUF_USRFLAGMSK) == 0,
228	    ("%s called with invalid flags", __func__));
229
230	flags &= SBUF_USRFLAGMSK;
231	if (s != NULL)
232		return (sbuf_newbuf(s, buf, length, flags));
233
234	s = SBMALLOC(sizeof(*s));
235	if (s == NULL)
236		return (NULL);
237	if (sbuf_newbuf(s, buf, length, flags) == NULL) {
238		SBFREE(s);
239		return (NULL);
240	}
241	SBUF_SETFLAG(s, SBUF_DYNSTRUCT);
242	return (s);
243}
244
245#ifdef _KERNEL
246/*
247 * Create an sbuf with uio data
248 */
249struct sbuf *
250sbuf_uionew(struct sbuf *s, struct uio *uio, int *error)
251{
252
253	KASSERT(uio != NULL,
254	    ("%s called with NULL uio pointer", __func__));
255	KASSERT(error != NULL,
256	    ("%s called with NULL error pointer", __func__));
257
258	s = sbuf_new(s, NULL, uio->uio_resid + 1, 0);
259	if (s == NULL) {
260		*error = ENOMEM;
261		return (NULL);
262	}
263	*error = uiomove(s->s_buf, uio->uio_resid, uio);
264	if (*error != 0) {
265		sbuf_delete(s);
266		return (NULL);
267	}
268	s->s_len = s->s_size - 1;
269	if (SBUF_ISSECTION(s))
270		s->s_sect_len = s->s_size - 1;
271	*error = 0;
272	return (s);
273}
274#endif
275
276int
277sbuf_get_flags(struct sbuf *s)
278{
279
280	return (s->s_flags & SBUF_USRFLAGMSK);
281}
282
283void
284sbuf_clear_flags(struct sbuf *s, int flags)
285{
286
287	s->s_flags &= ~(flags & SBUF_USRFLAGMSK);
288}
289
290void
291sbuf_set_flags(struct sbuf *s, int flags)
292{
293
294
295	s->s_flags |= (flags & SBUF_USRFLAGMSK);
296}
297
298/*
299 * Clear an sbuf and reset its position.
300 */
301void
302sbuf_clear(struct sbuf *s)
303{
304
305	assert_sbuf_integrity(s);
306	/* don't care if it's finished or not */
307
308	SBUF_CLEARFLAG(s, SBUF_FINISHED);
309	s->s_error = 0;
310	s->s_len = 0;
311	s->s_sect_len = 0;
312}
313
314/*
315 * Set the sbuf's end position to an arbitrary value.
316 * Effectively truncates the sbuf at the new position.
317 */
318int
319sbuf_setpos(struct sbuf *s, ssize_t pos)
320{
321
322	assert_sbuf_integrity(s);
323	assert_sbuf_state(s, 0);
324
325	KASSERT(pos >= 0,
326	    ("attempt to seek to a negative position (%jd)", (intmax_t)pos));
327	KASSERT(pos < s->s_size,
328	    ("attempt to seek past end of sbuf (%jd >= %jd)",
329	    (intmax_t)pos, (intmax_t)s->s_size));
330	KASSERT(!SBUF_ISSECTION(s),
331	    ("attempt to seek when in a section"));
332
333	if (pos < 0 || pos > s->s_len)
334		return (-1);
335	s->s_len = pos;
336	return (0);
337}
338
339/*
340 * Set up a drain function and argument on an sbuf to flush data to
341 * when the sbuf buffer overflows.
342 */
343void
344sbuf_set_drain(struct sbuf *s, sbuf_drain_func *func, void *ctx)
345{
346
347	assert_sbuf_state(s, 0);
348	assert_sbuf_integrity(s);
349	KASSERT(func == s->s_drain_func || s->s_len == 0,
350	    ("Cannot change drain to %p on non-empty sbuf %p", func, s));
351	s->s_drain_func = func;
352	s->s_drain_arg = ctx;
353}
354
355/*
356 * Call the drain and process the return.
357 */
358static int
359sbuf_drain(struct sbuf *s)
360{
361	int len;
362
363	KASSERT(s->s_len > 0, ("Shouldn't drain empty sbuf %p", s));
364	KASSERT(s->s_error == 0, ("Called %s with error on %p", __func__, s));
365	len = s->s_drain_func(s->s_drain_arg, s->s_buf, s->s_len);
366	if (len < 0) {
367		s->s_error = -len;
368		return (s->s_error);
369	}
370	KASSERT(len > 0 && len <= s->s_len,
371	    ("Bad drain amount %d for sbuf %p", len, s));
372	s->s_len -= len;
373	/*
374	 * Fast path for the expected case where all the data was
375	 * drained.
376	 */
377	if (s->s_len == 0)
378		return (0);
379	/*
380	 * Move the remaining characters to the beginning of the
381	 * string.
382	 */
383	memmove(s->s_buf, s->s_buf + len, s->s_len);
384	return (0);
385}
386
387/*
388 * Append bytes to an sbuf.  This is the core function for appending
389 * to an sbuf and is the main place that deals with extending the
390 * buffer and marking overflow.
391 */
392static void
393sbuf_put_bytes(struct sbuf *s, const char *buf, size_t len)
394{
395	size_t n;
396
397	assert_sbuf_integrity(s);
398	assert_sbuf_state(s, 0);
399
400	if (s->s_error != 0)
401		return;
402	while (len > 0) {
403		if (SBUF_FREESPACE(s) <= 0) {
404			/*
405			 * If there is a drain, use it, otherwise extend the
406			 * buffer.
407			 */
408			if (s->s_drain_func != NULL)
409				(void)sbuf_drain(s);
410			else if (sbuf_extend(s, len > INT_MAX ? INT_MAX : len)
411			    < 0)
412				s->s_error = ENOMEM;
413			if (s->s_error != 0)
414				return;
415		}
416		n = SBUF_FREESPACE(s);
417		if (len < n)
418			n = len;
419		memcpy(&s->s_buf[s->s_len], buf, n);
420		s->s_len += n;
421		if (SBUF_ISSECTION(s))
422			s->s_sect_len += n;
423		len -= n;
424		buf += n;
425	}
426}
427
428static void
429sbuf_put_byte(struct sbuf *s, char c)
430{
431
432	sbuf_put_bytes(s, &c, 1);
433}
434
435/*
436 * Append a byte string to an sbuf.
437 */
438int
439sbuf_bcat(struct sbuf *s, const void *buf, size_t len)
440{
441
442	sbuf_put_bytes(s, buf, len);
443	if (s->s_error != 0)
444		return (-1);
445	return (0);
446}
447
448#ifdef _KERNEL
449/*
450 * Copy a byte string from userland into an sbuf.
451 */
452int
453sbuf_bcopyin(struct sbuf *s, const void *uaddr, size_t len)
454{
455
456	assert_sbuf_integrity(s);
457	assert_sbuf_state(s, 0);
458	KASSERT(s->s_drain_func == NULL,
459	    ("Nonsensical copyin to sbuf %p with a drain", s));
460
461	if (s->s_error != 0)
462		return (-1);
463	if (len == 0)
464		return (0);
465	if (len > SBUF_FREESPACE(s)) {
466		sbuf_extend(s, len - SBUF_FREESPACE(s));
467		if (SBUF_FREESPACE(s) < len)
468			len = SBUF_FREESPACE(s);
469	}
470	if (copyin(uaddr, s->s_buf + s->s_len, len) != 0)
471		return (-1);
472	s->s_len += len;
473
474	return (0);
475}
476#endif
477
478/*
479 * Copy a byte string into an sbuf.
480 */
481int
482sbuf_bcpy(struct sbuf *s, const void *buf, size_t len)
483{
484
485	assert_sbuf_integrity(s);
486	assert_sbuf_state(s, 0);
487
488	sbuf_clear(s);
489	return (sbuf_bcat(s, buf, len));
490}
491
492/*
493 * Append a string to an sbuf.
494 */
495int
496sbuf_cat(struct sbuf *s, const char *str)
497{
498	size_t n;
499
500	n = strlen(str);
501	sbuf_put_bytes(s, str, n);
502	if (s->s_error != 0)
503		return (-1);
504	return (0);
505}
506
507#ifdef _KERNEL
508/*
509 * Append a string from userland to an sbuf.
510 */
511int
512sbuf_copyin(struct sbuf *s, const void *uaddr, size_t len)
513{
514	size_t done;
515
516	assert_sbuf_integrity(s);
517	assert_sbuf_state(s, 0);
518	KASSERT(s->s_drain_func == NULL,
519	    ("Nonsensical copyin to sbuf %p with a drain", s));
520
521	if (s->s_error != 0)
522		return (-1);
523
524	if (len == 0)
525		len = SBUF_FREESPACE(s);	/* XXX return 0? */
526	if (len > SBUF_FREESPACE(s)) {
527		sbuf_extend(s, len);
528		if (SBUF_FREESPACE(s) < len)
529			len = SBUF_FREESPACE(s);
530	}
531	switch (copyinstr(uaddr, s->s_buf + s->s_len, len + 1, &done)) {
532	case ENAMETOOLONG:
533		s->s_error = ENOMEM;
534		/* fall through */
535	case 0:
536		s->s_len += done - 1;
537		if (SBUF_ISSECTION(s))
538			s->s_sect_len += done - 1;
539		break;
540	default:
541		return (-1);	/* XXX */
542	}
543
544	return (done);
545}
546#endif
547
548/*
549 * Copy a string into an sbuf.
550 */
551int
552sbuf_cpy(struct sbuf *s, const char *str)
553{
554
555	assert_sbuf_integrity(s);
556	assert_sbuf_state(s, 0);
557
558	sbuf_clear(s);
559	return (sbuf_cat(s, str));
560}
561
562/*
563 * Format the given argument list and append the resulting string to an sbuf.
564 */
565#ifdef _KERNEL
566
567/*
568 * Append a non-NUL character to an sbuf.  This prototype signature is
569 * suitable for use with kvprintf(9).
570 */
571static void
572sbuf_putc_func(int c, void *arg)
573{
574
575	if (c != '\0')
576		sbuf_put_byte(arg, c);
577}
578
579int
580sbuf_vprintf(struct sbuf *s, const char *fmt, va_list ap)
581{
582
583	assert_sbuf_integrity(s);
584	assert_sbuf_state(s, 0);
585
586	KASSERT(fmt != NULL,
587	    ("%s called with a NULL format string", __func__));
588
589	(void)kvprintf(fmt, sbuf_putc_func, s, 10, ap);
590	if (s->s_error != 0)
591		return (-1);
592	return (0);
593}
594#else /* !_KERNEL */
595int
596sbuf_vprintf(struct sbuf *s, const char *fmt, va_list ap)
597{
598	va_list ap_copy;
599	int error, len;
600
601	assert_sbuf_integrity(s);
602	assert_sbuf_state(s, 0);
603
604	KASSERT(fmt != NULL,
605	    ("%s called with a NULL format string", __func__));
606
607	if (s->s_error != 0)
608		return (-1);
609
610	/*
611	 * For the moment, there is no way to get vsnprintf(3) to hand
612	 * back a character at a time, to push everything into
613	 * sbuf_putc_func() as was done for the kernel.
614	 *
615	 * In userspace, while drains are useful, there's generally
616	 * not a problem attempting to malloc(3) on out of space.  So
617	 * expand a userland sbuf if there is not enough room for the
618	 * data produced by sbuf_[v]printf(3).
619	 */
620
621	error = 0;
622	do {
623		va_copy(ap_copy, ap);
624		len = vsnprintf(&s->s_buf[s->s_len], SBUF_FREESPACE(s) + 1,
625		    fmt, ap_copy);
626		if (len < 0) {
627			s->s_error = errno;
628			return (-1);
629		}
630		va_end(ap_copy);
631
632		if (SBUF_FREESPACE(s) >= len)
633			break;
634		/* Cannot print with the current available space. */
635		if (s->s_drain_func != NULL && s->s_len > 0)
636			error = sbuf_drain(s);
637		else
638			error = sbuf_extend(s, len - SBUF_FREESPACE(s));
639	} while (error == 0);
640
641	/*
642	 * s->s_len is the length of the string, without the terminating nul.
643	 * When updating s->s_len, we must subtract 1 from the length that
644	 * we passed into vsnprintf() because that length includes the
645	 * terminating nul.
646	 *
647	 * vsnprintf() returns the amount that would have been copied,
648	 * given sufficient space, so don't over-increment s_len.
649	 */
650	if (SBUF_FREESPACE(s) < len)
651		len = SBUF_FREESPACE(s);
652	s->s_len += len;
653	if (SBUF_ISSECTION(s))
654		s->s_sect_len += len;
655	if (!SBUF_HASROOM(s) && !SBUF_CANEXTEND(s))
656		s->s_error = ENOMEM;
657
658	KASSERT(s->s_len < s->s_size,
659	    ("wrote past end of sbuf (%d >= %d)", s->s_len, s->s_size));
660
661	if (s->s_error != 0)
662		return (-1);
663	return (0);
664}
665#endif /* _KERNEL */
666
667/*
668 * Format the given arguments and append the resulting string to an sbuf.
669 */
670int
671sbuf_printf(struct sbuf *s, const char *fmt, ...)
672{
673	va_list ap;
674	int result;
675
676	va_start(ap, fmt);
677	result = sbuf_vprintf(s, fmt, ap);
678	va_end(ap);
679	return (result);
680}
681
682/*
683 * Append a character to an sbuf.
684 */
685int
686sbuf_putc(struct sbuf *s, int c)
687{
688
689	sbuf_put_byte(s, c);
690	if (s->s_error != 0)
691		return (-1);
692	return (0);
693}
694
695/*
696 * Trim whitespace characters from end of an sbuf.
697 */
698int
699sbuf_trim(struct sbuf *s)
700{
701
702	assert_sbuf_integrity(s);
703	assert_sbuf_state(s, 0);
704	KASSERT(s->s_drain_func == NULL,
705	    ("%s makes no sense on sbuf %p with drain", __func__, s));
706
707	if (s->s_error != 0)
708		return (-1);
709
710	while (s->s_len > 0 && isspace(s->s_buf[s->s_len-1])) {
711		--s->s_len;
712		if (SBUF_ISSECTION(s))
713			s->s_sect_len--;
714	}
715
716	return (0);
717}
718
719/*
720 * Check if an sbuf has an error.
721 */
722int
723sbuf_error(const struct sbuf *s)
724{
725
726	return (s->s_error);
727}
728
729/*
730 * Finish off an sbuf.
731 */
732int
733sbuf_finish(struct sbuf *s)
734{
735
736	assert_sbuf_integrity(s);
737	assert_sbuf_state(s, 0);
738
739	s->s_buf[s->s_len] = '\0';
740	if (SBUF_NULINCLUDED(s))
741		s->s_len++;
742	if (s->s_drain_func != NULL) {
743		while (s->s_len > 0 && s->s_error == 0)
744			s->s_error = sbuf_drain(s);
745	}
746	SBUF_SETFLAG(s, SBUF_FINISHED);
747#ifdef _KERNEL
748	return (s->s_error);
749#else
750	if (s->s_error != 0) {
751		errno = s->s_error;
752		return (-1);
753	}
754	return (0);
755#endif
756}
757
758/*
759 * Return a pointer to the sbuf data.
760 */
761char *
762sbuf_data(struct sbuf *s)
763{
764
765	assert_sbuf_integrity(s);
766	assert_sbuf_state(s, SBUF_FINISHED);
767	KASSERT(s->s_drain_func == NULL,
768	    ("%s makes no sense on sbuf %p with drain", __func__, s));
769
770	return (s->s_buf);
771}
772
773/*
774 * Return the length of the sbuf data.
775 */
776ssize_t
777sbuf_len(struct sbuf *s)
778{
779
780	assert_sbuf_integrity(s);
781	/* don't care if it's finished or not */
782	KASSERT(s->s_drain_func == NULL,
783	    ("%s makes no sense on sbuf %p with drain", __func__, s));
784
785	if (s->s_error != 0)
786		return (-1);
787
788	/* If finished, nulterm is already in len, else add one. */
789	if (SBUF_NULINCLUDED(s) && !SBUF_ISFINISHED(s))
790		return (s->s_len + 1);
791	return (s->s_len);
792}
793
794/*
795 * Clear an sbuf, free its buffer if necessary.
796 */
797void
798sbuf_delete(struct sbuf *s)
799{
800	int isdyn;
801
802	assert_sbuf_integrity(s);
803	/* don't care if it's finished or not */
804
805	if (SBUF_ISDYNAMIC(s))
806		SBFREE(s->s_buf);
807	isdyn = SBUF_ISDYNSTRUCT(s);
808	memset(s, 0, sizeof(*s));
809	if (isdyn)
810		SBFREE(s);
811}
812
813/*
814 * Check if an sbuf has been finished.
815 */
816int
817sbuf_done(const struct sbuf *s)
818{
819
820	return (SBUF_ISFINISHED(s));
821}
822
823/*
824 * Start a section.
825 */
826void
827sbuf_start_section(struct sbuf *s, ssize_t *old_lenp)
828{
829
830	assert_sbuf_integrity(s);
831	assert_sbuf_state(s, 0);
832
833	if (!SBUF_ISSECTION(s)) {
834		KASSERT(s->s_sect_len == 0,
835		    ("s_sect_len != 0 when starting a section"));
836		if (old_lenp != NULL)
837			*old_lenp = -1;
838		SBUF_SETFLAG(s, SBUF_INSECTION);
839	} else {
840		KASSERT(old_lenp != NULL,
841		    ("s_sect_len should be saved when starting a subsection"));
842		*old_lenp = s->s_sect_len;
843		s->s_sect_len = 0;
844	}
845}
846
847/*
848 * End the section padding to the specified length with the specified
849 * character.
850 */
851ssize_t
852sbuf_end_section(struct sbuf *s, ssize_t old_len, size_t pad, int c)
853{
854	ssize_t len;
855
856	assert_sbuf_integrity(s);
857	assert_sbuf_state(s, 0);
858	KASSERT(SBUF_ISSECTION(s),
859	    ("attempt to end a section when not in a section"));
860
861	if (pad > 1) {
862		len = roundup(s->s_sect_len, pad) - s->s_sect_len;
863		for (; s->s_error == 0 && len > 0; len--)
864			sbuf_put_byte(s, c);
865	}
866	len = s->s_sect_len;
867	if (old_len == -1) {
868		s->s_sect_len = 0;
869		SBUF_CLEARFLAG(s, SBUF_INSECTION);
870	} else {
871		s->s_sect_len += old_len;
872	}
873	if (s->s_error != 0)
874		return (-1);
875	return (len);
876}
877