subr_sbuf.c revision 212367 
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 212367 2010-09-09 17:49:18Z mdf $");
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/malloc.h>
39#include <sys/systm.h>
40#include <sys/uio.h>
41#include <machine/stdarg.h>
42#else /* _KERNEL */
43#include <ctype.h>
44#include <errno.h>
45#include <stdarg.h>
46#include <stdio.h>
47#include <stdlib.h>
48#include <string.h>
49#endif /* _KERNEL */
50
51#include <sys/sbuf.h>
52
53#ifdef _KERNEL
54static MALLOC_DEFINE(M_SBUF, "sbuf", "string buffers");
55#define	SBMALLOC(size)		malloc(size, M_SBUF, M_WAITOK)
56#define	SBFREE(buf)		free(buf, M_SBUF)
57#else /* _KERNEL */
58#define	KASSERT(e, m)
59#define	SBMALLOC(size)		malloc(size)
60#define	SBFREE(buf)		free(buf)
61#endif /* _KERNEL */
62
63/*
64 * Predicates
65 */
66#define	SBUF_ISDYNAMIC(s)	((s)->s_flags & SBUF_DYNAMIC)
67#define	SBUF_ISDYNSTRUCT(s)	((s)->s_flags & SBUF_DYNSTRUCT)
68#define	SBUF_ISFINISHED(s)	((s)->s_flags & SBUF_FINISHED)
69#define	SBUF_HASOVERFLOWED(s)	((s)->s_flags & SBUF_OVERFLOWED)
70#define	SBUF_HASROOM(s)		((s)->s_len < (s)->s_size - 1)
71#define	SBUF_FREESPACE(s)	((s)->s_size - (s)->s_len - 1)
72#define	SBUF_CANEXTEND(s)	((s)->s_flags & SBUF_AUTOEXTEND)
73
74/*
75 * Set / clear flags
76 */
77#define	SBUF_SETFLAG(s, f)	do { (s)->s_flags |= (f); } while (0)
78#define	SBUF_CLEARFLAG(s, f)	do { (s)->s_flags &= ~(f); } while (0)
79
80#define	SBUF_MINEXTENDSIZE	16		/* Should be power of 2. */
81#define	SBUF_MAXEXTENDSIZE	PAGE_SIZE
82#define	SBUF_MAXEXTENDINCR	PAGE_SIZE
83
84/*
85 * Debugging support
86 */
87#if defined(_KERNEL) && defined(INVARIANTS)
88
89static void
90_assert_sbuf_integrity(const char *fun, struct sbuf *s)
91{
92
93	KASSERT(s != NULL,
94	    ("%s called with a NULL sbuf pointer", fun));
95	KASSERT(s->s_buf != NULL,
96	    ("%s called with uninitialized or corrupt sbuf", fun));
97	KASSERT(s->s_len < s->s_size,
98	    ("wrote past end of sbuf (%d >= %d)", s->s_len, s->s_size));
99}
100
101static void
102_assert_sbuf_state(const char *fun, struct sbuf *s, int state)
103{
104
105	KASSERT((s->s_flags & SBUF_FINISHED) == state,
106	    ("%s called with %sfinished or corrupt sbuf", fun,
107	    (state ? "un" : "")));
108}
109
110#define	assert_sbuf_integrity(s) _assert_sbuf_integrity(__func__, (s))
111#define	assert_sbuf_state(s, i)	 _assert_sbuf_state(__func__, (s), (i))
112
113#else /* _KERNEL && INVARIANTS */
114
115#define	assert_sbuf_integrity(s) do { } while (0)
116#define	assert_sbuf_state(s, i)	 do { } while (0)
117
118#endif /* _KERNEL && INVARIANTS */
119
120#ifdef CTASSERT
121CTASSERT(powerof2(SBUF_MAXEXTENDSIZE));
122CTASSERT(powerof2(SBUF_MAXEXTENDINCR));
123#endif
124
125static int
126sbuf_extendsize(int size)
127{
128	int newsize;
129
130	if (size < (int)SBUF_MAXEXTENDSIZE) {
131		newsize = SBUF_MINEXTENDSIZE;
132		while (newsize < size)
133			newsize *= 2;
134	} else {
135		newsize = roundup2(size, SBUF_MAXEXTENDINCR);
136	}
137	KASSERT(newsize >= size, ("%s: %d < %d\n", __func__, newsize, size));
138	return (newsize);
139}
140
141
142/*
143 * Extend an sbuf.
144 */
145static int
146sbuf_extend(struct sbuf *s, int addlen)
147{
148	char *newbuf;
149	int newsize;
150
151	if (!SBUF_CANEXTEND(s))
152		return (-1);
153	newsize = sbuf_extendsize(s->s_size + addlen);
154	newbuf = SBMALLOC(newsize);
155	if (newbuf == NULL)
156		return (-1);
157	bcopy(s->s_buf, newbuf, s->s_size);
158	if (SBUF_ISDYNAMIC(s))
159		SBFREE(s->s_buf);
160	else
161		SBUF_SETFLAG(s, SBUF_DYNAMIC);
162	s->s_buf = newbuf;
163	s->s_size = newsize;
164	return (0);
165}
166
167/*
168 * Initialize an sbuf.
169 * If buf is non-NULL, it points to a static or already-allocated string
170 * big enough to hold at least length characters.
171 */
172struct sbuf *
173sbuf_new(struct sbuf *s, char *buf, int length, int flags)
174{
175
176	KASSERT(length >= 0,
177	    ("attempt to create an sbuf of negative length (%d)", length));
178	KASSERT((flags & ~SBUF_USRFLAGMSK) == 0,
179	    ("%s called with invalid flags", __func__));
180
181	flags &= SBUF_USRFLAGMSK;
182	if (s == NULL) {
183		s = SBMALLOC(sizeof(*s));
184		if (s == NULL)
185			return (NULL);
186		bzero(s, sizeof(*s));
187		s->s_flags = flags;
188		SBUF_SETFLAG(s, SBUF_DYNSTRUCT);
189	} else {
190		bzero(s, sizeof(*s));
191		s->s_flags = flags;
192	}
193	s->s_size = length;
194	if (buf != NULL) {
195		s->s_buf = buf;
196		return (s);
197	}
198	if ((flags & SBUF_AUTOEXTEND) != 0)
199		s->s_size = sbuf_extendsize(s->s_size);
200	s->s_buf = SBMALLOC(s->s_size);
201	if (s->s_buf == NULL) {
202		if (SBUF_ISDYNSTRUCT(s))
203			SBFREE(s);
204		return (NULL);
205	}
206	SBUF_SETFLAG(s, SBUF_DYNAMIC);
207	return (s);
208}
209
210#ifdef _KERNEL
211/*
212 * Create an sbuf with uio data
213 */
214struct sbuf *
215sbuf_uionew(struct sbuf *s, struct uio *uio, int *error)
216{
217
218	KASSERT(uio != NULL,
219	    ("%s called with NULL uio pointer", __func__));
220	KASSERT(error != NULL,
221	    ("%s called with NULL error pointer", __func__));
222
223	s = sbuf_new(s, NULL, uio->uio_resid + 1, 0);
224	if (s == NULL) {
225		*error = ENOMEM;
226		return (NULL);
227	}
228	*error = uiomove(s->s_buf, uio->uio_resid, uio);
229	if (*error != 0) {
230		sbuf_delete(s);
231		return (NULL);
232	}
233	s->s_len = s->s_size - 1;
234	*error = 0;
235	return (s);
236}
237#endif
238
239/*
240 * Clear an sbuf and reset its position.
241 */
242void
243sbuf_clear(struct sbuf *s)
244{
245
246	assert_sbuf_integrity(s);
247	/* don't care if it's finished or not */
248
249	SBUF_CLEARFLAG(s, SBUF_FINISHED);
250	SBUF_CLEARFLAG(s, SBUF_OVERFLOWED);
251	s->s_error = 0;
252	s->s_len = 0;
253}
254
255/*
256 * Set the sbuf's end position to an arbitrary value.
257 * Effectively truncates the sbuf at the new position.
258 */
259int
260sbuf_setpos(struct sbuf *s, int pos)
261{
262
263	assert_sbuf_integrity(s);
264	assert_sbuf_state(s, 0);
265
266	KASSERT(pos >= 0,
267	    ("attempt to seek to a negative position (%d)", pos));
268	KASSERT(pos < s->s_size,
269	    ("attempt to seek past end of sbuf (%d >= %d)", pos, s->s_size));
270
271	if (pos < 0 || pos > s->s_len)
272		return (-1);
273	s->s_len = pos;
274	return (0);
275}
276
277/*
278 * Set up a drain function and argument on an sbuf to flush data to
279 * when the sbuf buffer overflows.
280 */
281void
282sbuf_set_drain(struct sbuf *s, sbuf_drain_func *func, void *ctx)
283{
284
285	assert_sbuf_state(s, 0);
286	assert_sbuf_integrity(s);
287	KASSERT(func == s->s_drain_func || s->s_len == 0,
288	    ("Cannot change drain to %p on non-empty sbuf %p", func, s));
289	s->s_drain_func = func;
290	s->s_drain_arg = ctx;
291}
292
293/*
294 * Call the drain and process the return.
295 */
296static int
297sbuf_drain(struct sbuf *s)
298{
299	int len;
300
301	KASSERT(s->s_len > 0, ("Shouldn't drain empty sbuf %p", s));
302	len = s->s_drain_func(s->s_drain_arg, s->s_buf, s->s_len);
303	if (len < 0) {
304		s->s_error = -len;
305		SBUF_SETFLAG(s, SBUF_OVERFLOWED);
306		return (s->s_error);
307	}
308
309	KASSERT(len > 0, ("Drain must either error or work!"));
310	s->s_len -= len;
311	/*
312	 * Fast path for the expected case where all the data was
313	 * drained.
314	 */
315	if (s->s_len == 0)
316		return (0);
317	/*
318	 * Move the remaining characters to the beginning of the
319	 * string.
320	 */
321	memmove(s->s_buf, s->s_buf + len, s->s_len);
322	return (0);
323}
324
325/*
326 * Append a byte to an sbuf.  This is the core function for appending
327 * to an sbuf and is the main place that deals with extending the
328 * buffer and marking overflow.
329 */
330static void
331sbuf_put_byte(int c, struct sbuf *s)
332{
333
334	assert_sbuf_integrity(s);
335	assert_sbuf_state(s, 0);
336
337	if (SBUF_HASOVERFLOWED(s))
338		return;
339	if (SBUF_FREESPACE(s) <= 0) {
340		/*
341		 * If there is a drain, use it, otherwise extend the
342		 * buffer.
343		 */
344		if (s->s_drain_func != NULL)
345			(void)sbuf_drain(s);
346		else if (sbuf_extend(s, 1) < 0)
347			SBUF_SETFLAG(s, SBUF_OVERFLOWED);
348		if (SBUF_HASOVERFLOWED(s))
349			return;
350	}
351	s->s_buf[s->s_len++] = c;
352}
353
354/*
355 * Append a non-NUL character to an sbuf.  This prototype signature is
356 * suitable for use with kvprintf(9).
357 */
358static void
359sbuf_putc_func(int c, void *arg)
360{
361
362	if (c != '\0')
363		sbuf_put_byte(c, arg);
364}
365
366/*
367 * Append a byte string to an sbuf.
368 */
369int
370sbuf_bcat(struct sbuf *s, const void *buf, size_t len)
371{
372	const char *str = buf;
373	const char *end = str + len;
374
375	assert_sbuf_integrity(s);
376	assert_sbuf_state(s, 0);
377
378	if (SBUF_HASOVERFLOWED(s))
379		return (-1);
380	for (; str < end; str++) {
381		sbuf_put_byte(*str, s);
382		if (SBUF_HASOVERFLOWED(s))
383			return (-1);
384 	}
385	return (0);
386}
387
388#ifdef _KERNEL
389/*
390 * Copy a byte string from userland into an sbuf.
391 */
392int
393sbuf_bcopyin(struct sbuf *s, const void *uaddr, size_t len)
394{
395
396	assert_sbuf_integrity(s);
397	assert_sbuf_state(s, 0);
398	KASSERT(s->s_drain_func == NULL,
399	    ("Nonsensical copyin to sbuf %p with a drain", s));
400
401	if (SBUF_HASOVERFLOWED(s))
402		return (-1);
403	if (len == 0)
404		return (0);
405	if (len > SBUF_FREESPACE(s)) {
406		sbuf_extend(s, len - SBUF_FREESPACE(s));
407		if (SBUF_FREESPACE(s) < len)
408			len = SBUF_FREESPACE(s);
409	}
410	if (copyin(uaddr, s->s_buf + s->s_len, len) != 0)
411		return (-1);
412	s->s_len += len;
413
414	return (0);
415}
416#endif
417
418/*
419 * Copy a byte string into an sbuf.
420 */
421int
422sbuf_bcpy(struct sbuf *s, const void *buf, size_t len)
423{
424
425	assert_sbuf_integrity(s);
426	assert_sbuf_state(s, 0);
427
428	sbuf_clear(s);
429	return (sbuf_bcat(s, buf, len));
430}
431
432/*
433 * Append a string to an sbuf.
434 */
435int
436sbuf_cat(struct sbuf *s, const char *str)
437{
438
439	assert_sbuf_integrity(s);
440	assert_sbuf_state(s, 0);
441
442	if (SBUF_HASOVERFLOWED(s))
443		return (-1);
444
445	while (*str != '\0') {
446		sbuf_put_byte(*str, s);
447		if (SBUF_HASOVERFLOWED(s))
448			return (-1);
449	}
450	return (0);
451}
452
453#ifdef _KERNEL
454/*
455 * Append a string from userland to an sbuf.
456 */
457int
458sbuf_copyin(struct sbuf *s, const void *uaddr, size_t len)
459{
460	size_t done;
461
462	assert_sbuf_integrity(s);
463	assert_sbuf_state(s, 0);
464	KASSERT(s->s_drain_func == NULL,
465	    ("Nonsensical copyin to sbuf %p with a drain", s));
466
467	if (SBUF_HASOVERFLOWED(s))
468		return (-1);
469
470	if (len == 0)
471		len = SBUF_FREESPACE(s);	/* XXX return 0? */
472	if (len > SBUF_FREESPACE(s)) {
473		sbuf_extend(s, len);
474		if (SBUF_FREESPACE(s) < len)
475			len = SBUF_FREESPACE(s);
476	}
477	switch (copyinstr(uaddr, s->s_buf + s->s_len, len + 1, &done)) {
478	case ENAMETOOLONG:
479		SBUF_SETFLAG(s, SBUF_OVERFLOWED);
480		/* fall through */
481	case 0:
482		s->s_len += done - 1;
483		break;
484	default:
485		return (-1);	/* XXX */
486	}
487
488	return (done);
489}
490#endif
491
492/*
493 * Copy a string into an sbuf.
494 */
495int
496sbuf_cpy(struct sbuf *s, const char *str)
497{
498
499	assert_sbuf_integrity(s);
500	assert_sbuf_state(s, 0);
501
502	sbuf_clear(s);
503	return (sbuf_cat(s, str));
504}
505
506/*
507 * Format the given argument list and append the resulting string to an sbuf.
508 */
509#ifdef _KERNEL
510int
511sbuf_vprintf(struct sbuf *s, const char *fmt, va_list ap)
512{
513
514	assert_sbuf_integrity(s);
515	assert_sbuf_state(s, 0);
516
517	KASSERT(fmt != NULL,
518	    ("%s called with a NULL format string", __func__));
519
520	(void)kvprintf(fmt, sbuf_putc_func, s, 10, ap);
521	if (SBUF_HASOVERFLOWED(s))
522		return (-1);
523	return (0);
524}
525#else /* !_KERNEL */
526int
527sbuf_vprintf(struct sbuf *s, const char *fmt, va_list ap)
528{
529	va_list ap_copy;
530	int error, len;
531
532	assert_sbuf_integrity(s);
533	assert_sbuf_state(s, 0);
534
535	KASSERT(fmt != NULL,
536	    ("%s called with a NULL format string", __func__));
537
538	if (SBUF_HASOVERFLOWED(s))
539		return (-1);
540
541	/*
542	 * For the moment, there is no way to get vsnprintf(3) to hand
543	 * back a character at a time, to push everything into
544	 * sbuf_putc_func() as was done for the kernel.
545	 *
546	 * In userspace, while drains are useful, there's generally
547	 * not a problem attempting to malloc(3) on out of space.  So
548	 * expand a userland sbuf if there is not enough room for the
549	 * data produced by sbuf_[v]printf(3).
550	 */
551
552	error = 0;
553	do {
554		va_copy(ap_copy, ap);
555		len = vsnprintf(&s->s_buf[s->s_len], SBUF_FREESPACE(s) + 1,
556		    fmt, ap_copy);
557		va_end(ap_copy);
558
559		if (SBUF_FREESPACE(s) >= len)
560			break;
561		/* Cannot print with the current available space. */
562		if (s->s_drain_func != NULL && s->s_len > 0)
563			error = sbuf_drain(s);
564		else
565			error = sbuf_extend(s, len - SBUF_FREESPACE(s));
566	} while (error == 0);
567
568	/*
569	 * s->s_len is the length of the string, without the terminating nul.
570	 * When updating s->s_len, we must subtract 1 from the length that
571	 * we passed into vsnprintf() because that length includes the
572	 * terminating nul.
573	 *
574	 * vsnprintf() returns the amount that would have been copied,
575	 * given sufficient space, so don't over-increment s_len.
576	 */
577	if (SBUF_FREESPACE(s) < len)
578		len = SBUF_FREESPACE(s);
579	s->s_len += len;
580	if (!SBUF_HASROOM(s) && !SBUF_CANEXTEND(s))
581		SBUF_SETFLAG(s, SBUF_OVERFLOWED);
582
583	KASSERT(s->s_len < s->s_size,
584	    ("wrote past end of sbuf (%d >= %d)", s->s_len, s->s_size));
585
586	if (SBUF_HASOVERFLOWED(s))
587		return (-1);
588	return (0);
589}
590#endif /* _KERNEL */
591
592/*
593 * Format the given arguments and append the resulting string to an sbuf.
594 */
595int
596sbuf_printf(struct sbuf *s, const char *fmt, ...)
597{
598	va_list ap;
599	int result;
600
601	va_start(ap, fmt);
602	result = sbuf_vprintf(s, fmt, ap);
603	va_end(ap);
604	return (result);
605}
606
607/*
608 * Append a character to an sbuf.
609 */
610int
611sbuf_putc(struct sbuf *s, int c)
612{
613
614	sbuf_putc_func(c, s);
615	if (SBUF_HASOVERFLOWED(s))
616		return (-1);
617	return (0);
618}
619
620/*
621 * Trim whitespace characters from end of an sbuf.
622 */
623int
624sbuf_trim(struct sbuf *s)
625{
626
627	assert_sbuf_integrity(s);
628	assert_sbuf_state(s, 0);
629	KASSERT(s->s_drain_func == NULL,
630	    ("%s makes no sense on sbuf %p with drain", __func__, s));
631
632	if (SBUF_HASOVERFLOWED(s))
633		return (-1);
634
635	while (s->s_len > 0 && isspace(s->s_buf[s->s_len-1]))
636		--s->s_len;
637
638	return (0);
639}
640
641/*
642 * Check if an sbuf overflowed
643 */
644int
645sbuf_overflowed(struct sbuf *s)
646{
647
648	return (SBUF_HASOVERFLOWED(s));
649}
650
651/*
652 * Finish off an sbuf.
653 */
654int
655sbuf_finish(struct sbuf *s)
656{
657	int error = 0;
658
659	assert_sbuf_integrity(s);
660	assert_sbuf_state(s, 0);
661
662	if (s->s_drain_func != NULL) {
663		error = s->s_error;
664		while (s->s_len > 0 && error == 0)
665			error = sbuf_drain(s);
666	} else if (SBUF_HASOVERFLOWED(s))
667		error = ENOMEM;
668	s->s_buf[s->s_len] = '\0';
669	SBUF_CLEARFLAG(s, SBUF_OVERFLOWED);
670	SBUF_SETFLAG(s, SBUF_FINISHED);
671#ifdef _KERNEL
672	return (error);
673#else
674	errno = error;
675	return (-1);
676#endif
677}
678
679/*
680 * Return a pointer to the sbuf data.
681 */
682char *
683sbuf_data(struct sbuf *s)
684{
685
686	assert_sbuf_integrity(s);
687	assert_sbuf_state(s, SBUF_FINISHED);
688	KASSERT(s->s_drain_func == NULL,
689	    ("%s makes no sense on sbuf %p with drain", __func__, s));
690
691	return (s->s_buf);
692}
693
694/*
695 * Return the length of the sbuf data.
696 */
697int
698sbuf_len(struct sbuf *s)
699{
700
701	assert_sbuf_integrity(s);
702	/* don't care if it's finished or not */
703	KASSERT(s->s_drain_func == NULL,
704	    ("%s makes no sense on sbuf %p with drain", __func__, s));
705
706	if (SBUF_HASOVERFLOWED(s))
707		return (-1);
708	return (s->s_len);
709}
710
711/*
712 * Clear an sbuf, free its buffer if necessary.
713 */
714void
715sbuf_delete(struct sbuf *s)
716{
717	int isdyn;
718
719	assert_sbuf_integrity(s);
720	/* don't care if it's finished or not */
721
722	if (SBUF_ISDYNAMIC(s))
723		SBFREE(s->s_buf);
724	isdyn = SBUF_ISDYNSTRUCT(s);
725	bzero(s, sizeof(*s));
726	if (isdyn)
727		SBFREE(s);
728}
729
730/*
731 * Check if an sbuf has been finished.
732 */
733int
734sbuf_done(struct sbuf *s)
735{
736
737	return (SBUF_ISFINISHED(s));
738}
739