subr_sbuf.c revision 212181 
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 212181 2010-09-03 16:12:39Z 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
119CTASSERT(powerof2(SBUF_MAXEXTENDSIZE));
120CTASSERT(powerof2(SBUF_MAXEXTENDINCR));
121
122static int
123sbuf_extendsize(int size)
124{
125	int newsize;
126
127	if (size < (int)SBUF_MAXEXTENDSIZE) {
128		newsize = SBUF_MINEXTENDSIZE;
129		while (newsize < size)
130			newsize *= 2;
131	} else {
132		newsize = roundup2(size, SBUF_MAXEXTENDINCR);
133	}
134	KASSERT(newsize >= size, ("%s: %d < %d\n", __func__, newsize, size));
135	return (newsize);
136}
137
138
139/*
140 * Extend an sbuf.
141 */
142static int
143sbuf_extend(struct sbuf *s, int addlen)
144{
145	char *newbuf;
146	int newsize;
147
148	if (!SBUF_CANEXTEND(s))
149		return (-1);
150	newsize = sbuf_extendsize(s->s_size + addlen);
151	newbuf = SBMALLOC(newsize);
152	if (newbuf == NULL)
153		return (-1);
154	bcopy(s->s_buf, newbuf, s->s_size);
155	if (SBUF_ISDYNAMIC(s))
156		SBFREE(s->s_buf);
157	else
158		SBUF_SETFLAG(s, SBUF_DYNAMIC);
159	s->s_buf = newbuf;
160	s->s_size = newsize;
161	return (0);
162}
163
164/*
165 * Initialize an sbuf.
166 * If buf is non-NULL, it points to a static or already-allocated string
167 * big enough to hold at least length characters.
168 */
169struct sbuf *
170sbuf_new(struct sbuf *s, char *buf, int length, int flags)
171{
172
173	KASSERT(length >= 0,
174	    ("attempt to create an sbuf of negative length (%d)", length));
175	KASSERT((flags & ~SBUF_USRFLAGMSK) == 0,
176	    ("%s called with invalid flags", __func__));
177
178	flags &= SBUF_USRFLAGMSK;
179	if (s == NULL) {
180		s = SBMALLOC(sizeof(*s));
181		if (s == NULL)
182			return (NULL);
183		bzero(s, sizeof(*s));
184		s->s_flags = flags;
185		SBUF_SETFLAG(s, SBUF_DYNSTRUCT);
186	} else {
187		bzero(s, sizeof(*s));
188		s->s_flags = flags;
189	}
190	s->s_size = length;
191	if (buf) {
192		s->s_buf = buf;
193		return (s);
194	}
195	if (flags & SBUF_AUTOEXTEND)
196		s->s_size = sbuf_extendsize(s->s_size);
197	s->s_buf = SBMALLOC(s->s_size);
198	if (s->s_buf == NULL) {
199		if (SBUF_ISDYNSTRUCT(s))
200			SBFREE(s);
201		return (NULL);
202	}
203	SBUF_SETFLAG(s, SBUF_DYNAMIC);
204	return (s);
205}
206
207#ifdef _KERNEL
208/*
209 * Create an sbuf with uio data
210 */
211struct sbuf *
212sbuf_uionew(struct sbuf *s, struct uio *uio, int *error)
213{
214
215	KASSERT(uio != NULL,
216	    ("%s called with NULL uio pointer", __func__));
217	KASSERT(error != NULL,
218	    ("%s called with NULL error pointer", __func__));
219
220	s = sbuf_new(s, NULL, uio->uio_resid + 1, 0);
221	if (s == NULL) {
222		*error = ENOMEM;
223		return (NULL);
224	}
225	*error = uiomove(s->s_buf, uio->uio_resid, uio);
226	if (*error != 0) {
227		sbuf_delete(s);
228		return (NULL);
229	}
230	s->s_len = s->s_size - 1;
231	*error = 0;
232	return (s);
233}
234#endif
235
236/*
237 * Clear an sbuf and reset its position.
238 */
239void
240sbuf_clear(struct sbuf *s)
241{
242
243	assert_sbuf_integrity(s);
244	/* don't care if it's finished or not */
245
246	SBUF_CLEARFLAG(s, SBUF_FINISHED);
247	SBUF_CLEARFLAG(s, SBUF_OVERFLOWED);
248	s->s_len = 0;
249}
250
251/*
252 * Set the sbuf's end position to an arbitrary value.
253 * Effectively truncates the sbuf at the new position.
254 */
255int
256sbuf_setpos(struct sbuf *s, int pos)
257{
258
259	assert_sbuf_integrity(s);
260	assert_sbuf_state(s, 0);
261
262	KASSERT(pos >= 0,
263	    ("attempt to seek to a negative position (%d)", pos));
264	KASSERT(pos < s->s_size,
265	    ("attempt to seek past end of sbuf (%d >= %d)", pos, s->s_size));
266
267	if (pos < 0 || pos > s->s_len)
268		return (-1);
269	s->s_len = pos;
270	return (0);
271}
272
273/*
274 * Append a byte string to an sbuf.
275 */
276int
277sbuf_bcat(struct sbuf *s, const void *buf, size_t len)
278{
279	const char *str = buf;
280
281	assert_sbuf_integrity(s);
282	assert_sbuf_state(s, 0);
283
284	if (SBUF_HASOVERFLOWED(s))
285		return (-1);
286	for (; len; len--) {
287		if (!SBUF_HASROOM(s) && sbuf_extend(s, len) < 0)
288			break;
289		s->s_buf[s->s_len++] = *str++;
290	}
291	if (len) {
292		SBUF_SETFLAG(s, SBUF_OVERFLOWED);
293		return (-1);
294	}
295	return (0);
296}
297
298#ifdef _KERNEL
299/*
300 * Copy a byte string from userland into an sbuf.
301 */
302int
303sbuf_bcopyin(struct sbuf *s, const void *uaddr, size_t len)
304{
305
306	assert_sbuf_integrity(s);
307	assert_sbuf_state(s, 0);
308
309	if (SBUF_HASOVERFLOWED(s))
310		return (-1);
311	if (len == 0)
312		return (0);
313	if (len > SBUF_FREESPACE(s)) {
314		sbuf_extend(s, len - SBUF_FREESPACE(s));
315		len = min(len, SBUF_FREESPACE(s));
316	}
317	if (copyin(uaddr, s->s_buf + s->s_len, len) != 0)
318		return (-1);
319	s->s_len += len;
320
321	return (0);
322}
323#endif
324
325/*
326 * Copy a byte string into an sbuf.
327 */
328int
329sbuf_bcpy(struct sbuf *s, const void *buf, size_t len)
330{
331
332	assert_sbuf_integrity(s);
333	assert_sbuf_state(s, 0);
334
335	sbuf_clear(s);
336	return (sbuf_bcat(s, buf, len));
337}
338
339/*
340 * Append a string to an sbuf.
341 */
342int
343sbuf_cat(struct sbuf *s, const char *str)
344{
345
346	assert_sbuf_integrity(s);
347	assert_sbuf_state(s, 0);
348
349	if (SBUF_HASOVERFLOWED(s))
350		return (-1);
351
352	while (*str) {
353		if (!SBUF_HASROOM(s) && sbuf_extend(s, strlen(str)) < 0)
354			break;
355		s->s_buf[s->s_len++] = *str++;
356	}
357	if (*str) {
358		SBUF_SETFLAG(s, SBUF_OVERFLOWED);
359		return (-1);
360	}
361	return (0);
362}
363
364#ifdef _KERNEL
365/*
366 * Append a string from userland to an sbuf.
367 */
368int
369sbuf_copyin(struct sbuf *s, const void *uaddr, size_t len)
370{
371	size_t done;
372
373	assert_sbuf_integrity(s);
374	assert_sbuf_state(s, 0);
375
376	if (SBUF_HASOVERFLOWED(s))
377		return (-1);
378
379	if (len == 0)
380		len = SBUF_FREESPACE(s);	/* XXX return 0? */
381	if (len > SBUF_FREESPACE(s)) {
382		sbuf_extend(s, len);
383		len = min(len, SBUF_FREESPACE(s));
384	}
385	switch (copyinstr(uaddr, s->s_buf + s->s_len, len + 1, &done)) {
386	case ENAMETOOLONG:
387		SBUF_SETFLAG(s, SBUF_OVERFLOWED);
388		/* fall through */
389	case 0:
390		s->s_len += done - 1;
391		break;
392	default:
393		return (-1);	/* XXX */
394	}
395
396	return (done);
397}
398#endif
399
400/*
401 * Copy a string into an sbuf.
402 */
403int
404sbuf_cpy(struct sbuf *s, const char *str)
405{
406
407	assert_sbuf_integrity(s);
408	assert_sbuf_state(s, 0);
409
410	sbuf_clear(s);
411	return (sbuf_cat(s, str));
412}
413
414/*
415 * Format the given argument list and append the resulting string to an sbuf.
416 */
417int
418sbuf_vprintf(struct sbuf *s, const char *fmt, va_list ap)
419{
420	va_list ap_copy;
421	int len;
422
423	assert_sbuf_integrity(s);
424	assert_sbuf_state(s, 0);
425
426	KASSERT(fmt != NULL,
427	    ("%s called with a NULL format string", __func__));
428
429	if (SBUF_HASOVERFLOWED(s))
430		return (-1);
431
432	do {
433		va_copy(ap_copy, ap);
434		len = vsnprintf(&s->s_buf[s->s_len], SBUF_FREESPACE(s) + 1,
435		    fmt, ap_copy);
436		va_end(ap_copy);
437	} while (len > SBUF_FREESPACE(s) &&
438	    sbuf_extend(s, len - SBUF_FREESPACE(s)) == 0);
439
440	/*
441	 * s->s_len is the length of the string, without the terminating nul.
442	 * When updating s->s_len, we must subtract 1 from the length that
443	 * we passed into vsnprintf() because that length includes the
444	 * terminating nul.
445	 *
446	 * vsnprintf() returns the amount that would have been copied,
447	 * given sufficient space, hence the min() calculation below.
448	 */
449	s->s_len += min(len, SBUF_FREESPACE(s));
450	if (!SBUF_HASROOM(s) && !SBUF_CANEXTEND(s))
451		SBUF_SETFLAG(s, SBUF_OVERFLOWED);
452
453	KASSERT(s->s_len < s->s_size,
454	    ("wrote past end of sbuf (%d >= %d)", s->s_len, s->s_size));
455
456	if (SBUF_HASOVERFLOWED(s))
457		return (-1);
458	return (0);
459}
460
461/*
462 * Format the given arguments and append the resulting string to an sbuf.
463 */
464int
465sbuf_printf(struct sbuf *s, const char *fmt, ...)
466{
467	va_list ap;
468	int result;
469
470	va_start(ap, fmt);
471	result = sbuf_vprintf(s, fmt, ap);
472	va_end(ap);
473	return (result);
474}
475
476/*
477 * Append a character to an sbuf.
478 */
479int
480sbuf_putc(struct sbuf *s, int c)
481{
482
483	assert_sbuf_integrity(s);
484	assert_sbuf_state(s, 0);
485
486	if (SBUF_HASOVERFLOWED(s))
487		return (-1);
488	if (!SBUF_HASROOM(s) && sbuf_extend(s, 1) < 0) {
489		SBUF_SETFLAG(s, SBUF_OVERFLOWED);
490		return (-1);
491	}
492	if (c != '\0')
493	    s->s_buf[s->s_len++] = c;
494	return (0);
495}
496
497/*
498 * Trim whitespace characters from end of an sbuf.
499 */
500int
501sbuf_trim(struct sbuf *s)
502{
503
504	assert_sbuf_integrity(s);
505	assert_sbuf_state(s, 0);
506
507	if (SBUF_HASOVERFLOWED(s))
508		return (-1);
509
510	while (s->s_len && isspace(s->s_buf[s->s_len-1]))
511		--s->s_len;
512
513	return (0);
514}
515
516/*
517 * Check if an sbuf overflowed
518 */
519int
520sbuf_overflowed(struct sbuf *s)
521{
522
523	return (SBUF_HASOVERFLOWED(s));
524}
525
526/*
527 * Finish off an sbuf.
528 */
529void
530sbuf_finish(struct sbuf *s)
531{
532
533	assert_sbuf_integrity(s);
534	assert_sbuf_state(s, 0);
535
536	s->s_buf[s->s_len] = '\0';
537	SBUF_CLEARFLAG(s, SBUF_OVERFLOWED);
538	SBUF_SETFLAG(s, SBUF_FINISHED);
539}
540
541/*
542 * Return a pointer to the sbuf data.
543 */
544char *
545sbuf_data(struct sbuf *s)
546{
547
548	assert_sbuf_integrity(s);
549	assert_sbuf_state(s, SBUF_FINISHED);
550
551	return (s->s_buf);
552}
553
554/*
555 * Return the length of the sbuf data.
556 */
557int
558sbuf_len(struct sbuf *s)
559{
560
561	assert_sbuf_integrity(s);
562	/* don't care if it's finished or not */
563
564	if (SBUF_HASOVERFLOWED(s))
565		return (-1);
566	return (s->s_len);
567}
568
569/*
570 * Clear an sbuf, free its buffer if necessary.
571 */
572void
573sbuf_delete(struct sbuf *s)
574{
575	int isdyn;
576
577	assert_sbuf_integrity(s);
578	/* don't care if it's finished or not */
579
580	if (SBUF_ISDYNAMIC(s))
581		SBFREE(s->s_buf);
582	isdyn = SBUF_ISDYNSTRUCT(s);
583	bzero(s, sizeof(*s));
584	if (isdyn)
585		SBFREE(s);
586}
587
588/*
589 * Check if an sbuf has been finished.
590 */
591int
592sbuf_done(struct sbuf *s)
593{
594
595	return (SBUF_ISFINISHED(s));
596}
597