subr_sbuf.c revision 212182 
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 212182 2010-09-03 17:23:26Z mdf $");
31
32#include <sys/param.h>
33
34#ifdef _KERNEL
35#include <sys/ctype.h>
36#include <sys/kernel.h>
37#include <sys/malloc.h>
38#include <sys/systm.h>
39#include <sys/uio.h>
40#include <machine/stdarg.h>
41#else /* _KERNEL */
42#include <ctype.h>
43#include <stdarg.h>
44#include <stdio.h>
45#include <stdlib.h>
46#include <string.h>
47#endif /* _KERNEL */
48
49#include <sys/sbuf.h>
50
51#ifdef _KERNEL
52static MALLOC_DEFINE(M_SBUF, "sbuf", "string buffers");
53#define	SBMALLOC(size)		malloc(size, M_SBUF, M_WAITOK)
54#define	SBFREE(buf)		free(buf, M_SBUF)
55#else /* _KERNEL */
56#define	KASSERT(e, m)
57#define	SBMALLOC(size)		malloc(size)
58#define	SBFREE(buf)		free(buf)
59#define	min(x,y)		MIN(x,y)
60#endif /* _KERNEL */
61
62/*
63 * Predicates
64 */
65#define	SBUF_ISDYNAMIC(s)	((s)->s_flags & SBUF_DYNAMIC)
66#define	SBUF_ISDYNSTRUCT(s)	((s)->s_flags & SBUF_DYNSTRUCT)
67#define	SBUF_ISFINISHED(s)	((s)->s_flags & SBUF_FINISHED)
68#define	SBUF_HASOVERFLOWED(s)	((s)->s_flags & SBUF_OVERFLOWED)
69#define	SBUF_HASROOM(s)		((s)->s_len < (s)->s_size - 1)
70#define	SBUF_FREESPACE(s)	((s)->s_size - (s)->s_len - 1)
71#define	SBUF_CANEXTEND(s)	((s)->s_flags & SBUF_AUTOEXTEND)
72
73/*
74 * Set / clear flags
75 */
76#define	SBUF_SETFLAG(s, f)	do { (s)->s_flags |= (f); } while (0)
77#define	SBUF_CLEARFLAG(s, f)	do { (s)->s_flags &= ~(f); } while (0)
78
79#define	SBUF_MINEXTENDSIZE	16		/* Should be power of 2. */
80#define	SBUF_MAXEXTENDSIZE	PAGE_SIZE
81#define	SBUF_MAXEXTENDINCR	PAGE_SIZE
82
83/*
84 * Debugging support
85 */
86#if defined(_KERNEL) && defined(INVARIANTS)
87
88static void
89_assert_sbuf_integrity(const char *fun, struct sbuf *s)
90{
91
92	KASSERT(s != NULL,
93	    ("%s called with a NULL sbuf pointer", fun));
94	KASSERT(s->s_buf != NULL,
95	    ("%s called with uninitialized or corrupt sbuf", fun));
96	KASSERT(s->s_len < s->s_size,
97	    ("wrote past end of sbuf (%d >= %d)", s->s_len, s->s_size));
98}
99
100static void
101_assert_sbuf_state(const char *fun, struct sbuf *s, int state)
102{
103
104	KASSERT((s->s_flags & SBUF_FINISHED) == state,
105	    ("%s called with %sfinished or corrupt sbuf", fun,
106	    (state ? "un" : "")));
107}
108
109#define	assert_sbuf_integrity(s) _assert_sbuf_integrity(__func__, (s))
110#define	assert_sbuf_state(s, i)	 _assert_sbuf_state(__func__, (s), (i))
111
112#else /* _KERNEL && INVARIANTS */
113
114#define	assert_sbuf_integrity(s) do { } while (0)
115#define	assert_sbuf_state(s, i)	 do { } while (0)
116
117#endif /* _KERNEL && INVARIANTS */
118
119#ifdef _KERNEL
120CTASSERT(powerof2(SBUF_MAXEXTENDSIZE));
121CTASSERT(powerof2(SBUF_MAXEXTENDINCR));
122#endif
123
124static int
125sbuf_extendsize(int size)
126{
127	int newsize;
128
129	if (size < (int)SBUF_MAXEXTENDSIZE) {
130		newsize = SBUF_MINEXTENDSIZE;
131		while (newsize < size)
132			newsize *= 2;
133	} else {
134		newsize = roundup2(size, SBUF_MAXEXTENDINCR);
135	}
136	KASSERT(newsize >= size, ("%s: %d < %d\n", __func__, newsize, size));
137	return (newsize);
138}
139
140
141/*
142 * Extend an sbuf.
143 */
144static int
145sbuf_extend(struct sbuf *s, int addlen)
146{
147	char *newbuf;
148	int newsize;
149
150	if (!SBUF_CANEXTEND(s))
151		return (-1);
152	newsize = sbuf_extendsize(s->s_size + addlen);
153	newbuf = SBMALLOC(newsize);
154	if (newbuf == NULL)
155		return (-1);
156	bcopy(s->s_buf, newbuf, s->s_size);
157	if (SBUF_ISDYNAMIC(s))
158		SBFREE(s->s_buf);
159	else
160		SBUF_SETFLAG(s, SBUF_DYNAMIC);
161	s->s_buf = newbuf;
162	s->s_size = newsize;
163	return (0);
164}
165
166/*
167 * Initialize an sbuf.
168 * If buf is non-NULL, it points to a static or already-allocated string
169 * big enough to hold at least length characters.
170 */
171struct sbuf *
172sbuf_new(struct sbuf *s, char *buf, int length, int flags)
173{
174
175	KASSERT(length >= 0,
176	    ("attempt to create an sbuf of negative length (%d)", length));
177	KASSERT((flags & ~SBUF_USRFLAGMSK) == 0,
178	    ("%s called with invalid flags", __func__));
179
180	flags &= SBUF_USRFLAGMSK;
181	if (s == NULL) {
182		s = SBMALLOC(sizeof(*s));
183		if (s == NULL)
184			return (NULL);
185		bzero(s, sizeof(*s));
186		s->s_flags = flags;
187		SBUF_SETFLAG(s, SBUF_DYNSTRUCT);
188	} else {
189		bzero(s, sizeof(*s));
190		s->s_flags = flags;
191	}
192	s->s_size = length;
193	if (buf) {
194		s->s_buf = buf;
195		return (s);
196	}
197	if (flags & SBUF_AUTOEXTEND)
198		s->s_size = sbuf_extendsize(s->s_size);
199	s->s_buf = SBMALLOC(s->s_size);
200	if (s->s_buf == NULL) {
201		if (SBUF_ISDYNSTRUCT(s))
202			SBFREE(s);
203		return (NULL);
204	}
205	SBUF_SETFLAG(s, SBUF_DYNAMIC);
206	return (s);
207}
208
209#ifdef _KERNEL
210/*
211 * Create an sbuf with uio data
212 */
213struct sbuf *
214sbuf_uionew(struct sbuf *s, struct uio *uio, int *error)
215{
216
217	KASSERT(uio != NULL,
218	    ("%s called with NULL uio pointer", __func__));
219	KASSERT(error != NULL,
220	    ("%s called with NULL error pointer", __func__));
221
222	s = sbuf_new(s, NULL, uio->uio_resid + 1, 0);
223	if (s == NULL) {
224		*error = ENOMEM;
225		return (NULL);
226	}
227	*error = uiomove(s->s_buf, uio->uio_resid, uio);
228	if (*error != 0) {
229		sbuf_delete(s);
230		return (NULL);
231	}
232	s->s_len = s->s_size - 1;
233	*error = 0;
234	return (s);
235}
236#endif
237
238/*
239 * Clear an sbuf and reset its position.
240 */
241void
242sbuf_clear(struct sbuf *s)
243{
244
245	assert_sbuf_integrity(s);
246	/* don't care if it's finished or not */
247
248	SBUF_CLEARFLAG(s, SBUF_FINISHED);
249	SBUF_CLEARFLAG(s, SBUF_OVERFLOWED);
250	s->s_len = 0;
251}
252
253/*
254 * Set the sbuf's end position to an arbitrary value.
255 * Effectively truncates the sbuf at the new position.
256 */
257int
258sbuf_setpos(struct sbuf *s, int pos)
259{
260
261	assert_sbuf_integrity(s);
262	assert_sbuf_state(s, 0);
263
264	KASSERT(pos >= 0,
265	    ("attempt to seek to a negative position (%d)", pos));
266	KASSERT(pos < s->s_size,
267	    ("attempt to seek past end of sbuf (%d >= %d)", pos, s->s_size));
268
269	if (pos < 0 || pos > s->s_len)
270		return (-1);
271	s->s_len = pos;
272	return (0);
273}
274
275/*
276 * Append a byte string to an sbuf.
277 */
278int
279sbuf_bcat(struct sbuf *s, const void *buf, size_t len)
280{
281	const char *str = buf;
282
283	assert_sbuf_integrity(s);
284	assert_sbuf_state(s, 0);
285
286	if (SBUF_HASOVERFLOWED(s))
287		return (-1);
288	for (; len; len--) {
289		if (!SBUF_HASROOM(s) && sbuf_extend(s, len) < 0)
290			break;
291		s->s_buf[s->s_len++] = *str++;
292	}
293	if (len) {
294		SBUF_SETFLAG(s, SBUF_OVERFLOWED);
295		return (-1);
296	}
297	return (0);
298}
299
300#ifdef _KERNEL
301/*
302 * Copy a byte string from userland into an sbuf.
303 */
304int
305sbuf_bcopyin(struct sbuf *s, const void *uaddr, size_t len)
306{
307
308	assert_sbuf_integrity(s);
309	assert_sbuf_state(s, 0);
310
311	if (SBUF_HASOVERFLOWED(s))
312		return (-1);
313	if (len == 0)
314		return (0);
315	if (len > SBUF_FREESPACE(s)) {
316		sbuf_extend(s, len - SBUF_FREESPACE(s));
317		len = min(len, SBUF_FREESPACE(s));
318	}
319	if (copyin(uaddr, s->s_buf + s->s_len, len) != 0)
320		return (-1);
321	s->s_len += len;
322
323	return (0);
324}
325#endif
326
327/*
328 * Copy a byte string into an sbuf.
329 */
330int
331sbuf_bcpy(struct sbuf *s, const void *buf, size_t len)
332{
333
334	assert_sbuf_integrity(s);
335	assert_sbuf_state(s, 0);
336
337	sbuf_clear(s);
338	return (sbuf_bcat(s, buf, len));
339}
340
341/*
342 * Append a string to an sbuf.
343 */
344int
345sbuf_cat(struct sbuf *s, const char *str)
346{
347
348	assert_sbuf_integrity(s);
349	assert_sbuf_state(s, 0);
350
351	if (SBUF_HASOVERFLOWED(s))
352		return (-1);
353
354	while (*str) {
355		if (!SBUF_HASROOM(s) && sbuf_extend(s, strlen(str)) < 0)
356			break;
357		s->s_buf[s->s_len++] = *str++;
358	}
359	if (*str) {
360		SBUF_SETFLAG(s, SBUF_OVERFLOWED);
361		return (-1);
362	}
363	return (0);
364}
365
366#ifdef _KERNEL
367/*
368 * Append a string from userland to an sbuf.
369 */
370int
371sbuf_copyin(struct sbuf *s, const void *uaddr, size_t len)
372{
373	size_t done;
374
375	assert_sbuf_integrity(s);
376	assert_sbuf_state(s, 0);
377
378	if (SBUF_HASOVERFLOWED(s))
379		return (-1);
380
381	if (len == 0)
382		len = SBUF_FREESPACE(s);	/* XXX return 0? */
383	if (len > SBUF_FREESPACE(s)) {
384		sbuf_extend(s, len);
385		len = min(len, SBUF_FREESPACE(s));
386	}
387	switch (copyinstr(uaddr, s->s_buf + s->s_len, len + 1, &done)) {
388	case ENAMETOOLONG:
389		SBUF_SETFLAG(s, SBUF_OVERFLOWED);
390		/* fall through */
391	case 0:
392		s->s_len += done - 1;
393		break;
394	default:
395		return (-1);	/* XXX */
396	}
397
398	return (done);
399}
400#endif
401
402/*
403 * Copy a string into an sbuf.
404 */
405int
406sbuf_cpy(struct sbuf *s, const char *str)
407{
408
409	assert_sbuf_integrity(s);
410	assert_sbuf_state(s, 0);
411
412	sbuf_clear(s);
413	return (sbuf_cat(s, str));
414}
415
416/*
417 * Format the given argument list and append the resulting string to an sbuf.
418 */
419int
420sbuf_vprintf(struct sbuf *s, const char *fmt, va_list ap)
421{
422	va_list ap_copy;
423	int len;
424
425	assert_sbuf_integrity(s);
426	assert_sbuf_state(s, 0);
427
428	KASSERT(fmt != NULL,
429	    ("%s called with a NULL format string", __func__));
430
431	if (SBUF_HASOVERFLOWED(s))
432		return (-1);
433
434	do {
435		va_copy(ap_copy, ap);
436		len = vsnprintf(&s->s_buf[s->s_len], SBUF_FREESPACE(s) + 1,
437		    fmt, ap_copy);
438		va_end(ap_copy);
439	} while (len > SBUF_FREESPACE(s) &&
440	    sbuf_extend(s, len - SBUF_FREESPACE(s)) == 0);
441
442	/*
443	 * s->s_len is the length of the string, without the terminating nul.
444	 * When updating s->s_len, we must subtract 1 from the length that
445	 * we passed into vsnprintf() because that length includes the
446	 * terminating nul.
447	 *
448	 * vsnprintf() returns the amount that would have been copied,
449	 * given sufficient space, hence the min() calculation below.
450	 */
451	s->s_len += min(len, SBUF_FREESPACE(s));
452	if (!SBUF_HASROOM(s) && !SBUF_CANEXTEND(s))
453		SBUF_SETFLAG(s, SBUF_OVERFLOWED);
454
455	KASSERT(s->s_len < s->s_size,
456	    ("wrote past end of sbuf (%d >= %d)", s->s_len, s->s_size));
457
458	if (SBUF_HASOVERFLOWED(s))
459		return (-1);
460	return (0);
461}
462
463/*
464 * Format the given arguments and append the resulting string to an sbuf.
465 */
466int
467sbuf_printf(struct sbuf *s, const char *fmt, ...)
468{
469	va_list ap;
470	int result;
471
472	va_start(ap, fmt);
473	result = sbuf_vprintf(s, fmt, ap);
474	va_end(ap);
475	return (result);
476}
477
478/*
479 * Append a character to an sbuf.
480 */
481int
482sbuf_putc(struct sbuf *s, int c)
483{
484
485	assert_sbuf_integrity(s);
486	assert_sbuf_state(s, 0);
487
488	if (SBUF_HASOVERFLOWED(s))
489		return (-1);
490	if (!SBUF_HASROOM(s) && sbuf_extend(s, 1) < 0) {
491		SBUF_SETFLAG(s, SBUF_OVERFLOWED);
492		return (-1);
493	}
494	if (c != '\0')
495	    s->s_buf[s->s_len++] = c;
496	return (0);
497}
498
499/*
500 * Trim whitespace characters from end of an sbuf.
501 */
502int
503sbuf_trim(struct sbuf *s)
504{
505
506	assert_sbuf_integrity(s);
507	assert_sbuf_state(s, 0);
508
509	if (SBUF_HASOVERFLOWED(s))
510		return (-1);
511
512	while (s->s_len && isspace(s->s_buf[s->s_len-1]))
513		--s->s_len;
514
515	return (0);
516}
517
518/*
519 * Check if an sbuf overflowed
520 */
521int
522sbuf_overflowed(struct sbuf *s)
523{
524
525	return (SBUF_HASOVERFLOWED(s));
526}
527
528/*
529 * Finish off an sbuf.
530 */
531void
532sbuf_finish(struct sbuf *s)
533{
534
535	assert_sbuf_integrity(s);
536	assert_sbuf_state(s, 0);
537
538	s->s_buf[s->s_len] = '\0';
539	SBUF_CLEARFLAG(s, SBUF_OVERFLOWED);
540	SBUF_SETFLAG(s, SBUF_FINISHED);
541}
542
543/*
544 * Return a pointer to the sbuf data.
545 */
546char *
547sbuf_data(struct sbuf *s)
548{
549
550	assert_sbuf_integrity(s);
551	assert_sbuf_state(s, SBUF_FINISHED);
552
553	return (s->s_buf);
554}
555
556/*
557 * Return the length of the sbuf data.
558 */
559int
560sbuf_len(struct sbuf *s)
561{
562
563	assert_sbuf_integrity(s);
564	/* don't care if it's finished or not */
565
566	if (SBUF_HASOVERFLOWED(s))
567		return (-1);
568	return (s->s_len);
569}
570
571/*
572 * Clear an sbuf, free its buffer if necessary.
573 */
574void
575sbuf_delete(struct sbuf *s)
576{
577	int isdyn;
578
579	assert_sbuf_integrity(s);
580	/* don't care if it's finished or not */
581
582	if (SBUF_ISDYNAMIC(s))
583		SBFREE(s->s_buf);
584	isdyn = SBUF_ISDYNSTRUCT(s);
585	bzero(s, sizeof(*s));
586	if (isdyn)
587		SBFREE(s);
588}
589
590/*
591 * Check if an sbuf has been finished.
592 */
593int
594sbuf_done(struct sbuf *s)
595{
596
597	return (SBUF_ISFINISHED(s));
598}
599