subr_sbuf.c revision 224999
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 224999 2011-08-19 08:29:10Z rwatson $"); 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_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 81#ifdef PAGE_SIZE 82#define SBUF_MAXEXTENDSIZE PAGE_SIZE 83#define SBUF_MAXEXTENDINCR PAGE_SIZE 84#else 85#define SBUF_MAXEXTENDSIZE 4096 86#define SBUF_MAXEXTENDINCR 4096 87#endif 88 89/* 90 * Debugging support 91 */ 92#if defined(_KERNEL) && defined(INVARIANTS) 93 94static void 95_assert_sbuf_integrity(const char *fun, struct sbuf *s) 96{ 97 98 KASSERT(s != NULL, 99 ("%s called with a NULL sbuf pointer", fun)); 100 KASSERT(s->s_buf != NULL, 101 ("%s called with uninitialized or corrupt sbuf", fun)); 102 KASSERT(s->s_len < s->s_size, 103 ("wrote past end of sbuf (%jd >= %jd)", 104 (intmax_t)s->s_len, (intmax_t)s->s_size)); 105} 106 107static void 108_assert_sbuf_state(const char *fun, struct sbuf *s, int state) 109{ 110 111 KASSERT((s->s_flags & SBUF_FINISHED) == state, 112 ("%s called with %sfinished or corrupt sbuf", fun, 113 (state ? "un" : ""))); 114} 115 116#define assert_sbuf_integrity(s) _assert_sbuf_integrity(__func__, (s)) 117#define assert_sbuf_state(s, i) _assert_sbuf_state(__func__, (s), (i)) 118 119#else /* _KERNEL && INVARIANTS */ 120 121#define assert_sbuf_integrity(s) do { } while (0) 122#define assert_sbuf_state(s, i) do { } while (0) 123 124#endif /* _KERNEL && INVARIANTS */ 125 126#ifdef CTASSERT 127CTASSERT(powerof2(SBUF_MAXEXTENDSIZE)); 128CTASSERT(powerof2(SBUF_MAXEXTENDINCR)); 129#endif 130 131static int 132sbuf_extendsize(int size) 133{ 134 int newsize; 135 136 if (size < (int)SBUF_MAXEXTENDSIZE) { 137 newsize = SBUF_MINEXTENDSIZE; 138 while (newsize < size) 139 newsize *= 2; 140 } else { 141 newsize = roundup2(size, SBUF_MAXEXTENDINCR); 142 } 143 KASSERT(newsize >= size, ("%s: %d < %d\n", __func__, newsize, size)); 144 return (newsize); 145} 146 147/* 148 * Extend an sbuf. 149 */ 150static int 151sbuf_extend(struct sbuf *s, int addlen) 152{ 153 char *newbuf; 154 int newsize; 155 156 if (!SBUF_CANEXTEND(s)) 157 return (-1); 158 newsize = sbuf_extendsize(s->s_size + addlen); 159 newbuf = SBMALLOC(newsize); 160 if (newbuf == NULL) 161 return (-1); 162 memcpy(newbuf, s->s_buf, s->s_size); 163 if (SBUF_ISDYNAMIC(s)) 164 SBFREE(s->s_buf); 165 else 166 SBUF_SETFLAG(s, SBUF_DYNAMIC); 167 s->s_buf = newbuf; 168 s->s_size = newsize; 169 return (0); 170} 171 172/* 173 * Initialize the internals of an sbuf. 174 * If buf is non-NULL, it points to a static or already-allocated string 175 * big enough to hold at least length characters. 176 */ 177static struct sbuf * 178sbuf_newbuf(struct sbuf *s, char *buf, int length, int flags) 179{ 180 181 memset(s, 0, sizeof(*s)); 182 s->s_flags = flags; 183 s->s_size = length; 184 s->s_buf = buf; 185 186 if ((s->s_flags & SBUF_AUTOEXTEND) == 0) { 187 KASSERT(s->s_size >= 0, 188 ("attempt to create a too small sbuf")); 189 } 190 191 if (s->s_buf != NULL) 192 return (s); 193 194 if ((flags & SBUF_AUTOEXTEND) != 0) 195 s->s_size = sbuf_extendsize(s->s_size); 196 197 s->s_buf = SBMALLOC(s->s_size); 198 if (s->s_buf == NULL) 199 return (NULL); 200 SBUF_SETFLAG(s, SBUF_DYNAMIC); 201 return (s); 202} 203 204/* 205 * Initialize an sbuf. 206 * If buf is non-NULL, it points to a static or already-allocated string 207 * big enough to hold at least length characters. 208 */ 209struct sbuf * 210sbuf_new(struct sbuf *s, char *buf, int length, int flags) 211{ 212 213 KASSERT(length >= 0, 214 ("attempt to create an sbuf of negative length (%d)", length)); 215 KASSERT((flags & ~SBUF_USRFLAGMSK) == 0, 216 ("%s called with invalid flags", __func__)); 217 218 flags &= SBUF_USRFLAGMSK; 219 if (s != NULL) 220 return (sbuf_newbuf(s, buf, length, flags)); 221 222 s = SBMALLOC(sizeof(*s)); 223 if (s == NULL) 224 return (NULL); 225 if (sbuf_newbuf(s, buf, length, flags) == NULL) { 226 SBFREE(s); 227 return (NULL); 228 } 229 SBUF_SETFLAG(s, SBUF_DYNSTRUCT); 230 return (s); 231} 232 233#ifdef _KERNEL 234/* 235 * Create an sbuf with uio data 236 */ 237struct sbuf * 238sbuf_uionew(struct sbuf *s, struct uio *uio, int *error) 239{ 240 241 KASSERT(uio != NULL, 242 ("%s called with NULL uio pointer", __func__)); 243 KASSERT(error != NULL, 244 ("%s called with NULL error pointer", __func__)); 245 246 s = sbuf_new(s, NULL, uio->uio_resid + 1, 0); 247 if (s == NULL) { 248 *error = ENOMEM; 249 return (NULL); 250 } 251 *error = uiomove(s->s_buf, uio->uio_resid, uio); 252 if (*error != 0) { 253 sbuf_delete(s); 254 return (NULL); 255 } 256 s->s_len = s->s_size - 1; 257 *error = 0; 258 return (s); 259} 260#endif 261 262/* 263 * Clear an sbuf and reset its position. 264 */ 265void 266sbuf_clear(struct sbuf *s) 267{ 268 269 assert_sbuf_integrity(s); 270 /* don't care if it's finished or not */ 271 272 SBUF_CLEARFLAG(s, SBUF_FINISHED); 273 s->s_error = 0; 274 s->s_len = 0; 275} 276 277/* 278 * Set the sbuf's end position to an arbitrary value. 279 * Effectively truncates the sbuf at the new position. 280 */ 281int 282sbuf_setpos(struct sbuf *s, ssize_t pos) 283{ 284 285 assert_sbuf_integrity(s); 286 assert_sbuf_state(s, 0); 287 288 KASSERT(pos >= 0, 289 ("attempt to seek to a negative position (%jd)", (intmax_t)pos)); 290 KASSERT(pos < s->s_size, 291 ("attempt to seek past end of sbuf (%jd >= %jd)", 292 (intmax_t)pos, (intmax_t)s->s_size)); 293 294 if (pos < 0 || pos > s->s_len) 295 return (-1); 296 s->s_len = pos; 297 return (0); 298} 299 300/* 301 * Set up a drain function and argument on an sbuf to flush data to 302 * when the sbuf buffer overflows. 303 */ 304void 305sbuf_set_drain(struct sbuf *s, sbuf_drain_func *func, void *ctx) 306{ 307 308 assert_sbuf_state(s, 0); 309 assert_sbuf_integrity(s); 310 KASSERT(func == s->s_drain_func || s->s_len == 0, 311 ("Cannot change drain to %p on non-empty sbuf %p", func, s)); 312 s->s_drain_func = func; 313 s->s_drain_arg = ctx; 314} 315 316/* 317 * Call the drain and process the return. 318 */ 319static int 320sbuf_drain(struct sbuf *s) 321{ 322 int len; 323 324 KASSERT(s->s_len > 0, ("Shouldn't drain empty sbuf %p", s)); 325 KASSERT(s->s_error == 0, ("Called %s with error on %p", __func__, s)); 326 len = s->s_drain_func(s->s_drain_arg, s->s_buf, s->s_len); 327 if (len < 0) { 328 s->s_error = -len; 329 return (s->s_error); 330 } 331 KASSERT(len > 0 && len <= s->s_len, 332 ("Bad drain amount %d for sbuf %p", len, s)); 333 s->s_len -= len; 334 /* 335 * Fast path for the expected case where all the data was 336 * drained. 337 */ 338 if (s->s_len == 0) 339 return (0); 340 /* 341 * Move the remaining characters to the beginning of the 342 * string. 343 */ 344 memmove(s->s_buf, s->s_buf + len, s->s_len); 345 return (0); 346} 347 348/* 349 * Append a byte to an sbuf. This is the core function for appending 350 * to an sbuf and is the main place that deals with extending the 351 * buffer and marking overflow. 352 */ 353static void 354sbuf_put_byte(struct sbuf *s, int c) 355{ 356 357 assert_sbuf_integrity(s); 358 assert_sbuf_state(s, 0); 359 360 if (s->s_error != 0) 361 return; 362 if (SBUF_FREESPACE(s) <= 0) { 363 /* 364 * If there is a drain, use it, otherwise extend the 365 * buffer. 366 */ 367 if (s->s_drain_func != NULL) 368 (void)sbuf_drain(s); 369 else if (sbuf_extend(s, 1) < 0) 370 s->s_error = ENOMEM; 371 if (s->s_error != 0) 372 return; 373 } 374 s->s_buf[s->s_len++] = c; 375} 376 377/* 378 * Append a byte string to an sbuf. 379 */ 380int 381sbuf_bcat(struct sbuf *s, const void *buf, size_t len) 382{ 383 const char *str = buf; 384 const char *end = str + len; 385 386 assert_sbuf_integrity(s); 387 assert_sbuf_state(s, 0); 388 389 if (s->s_error != 0) 390 return (-1); 391 for (; str < end; str++) { 392 sbuf_put_byte(s, *str); 393 if (s->s_error != 0) 394 return (-1); 395 } 396 return (0); 397} 398 399#ifdef _KERNEL 400/* 401 * Copy a byte string from userland into an sbuf. 402 */ 403int 404sbuf_bcopyin(struct sbuf *s, const void *uaddr, size_t len) 405{ 406 407 assert_sbuf_integrity(s); 408 assert_sbuf_state(s, 0); 409 KASSERT(s->s_drain_func == NULL, 410 ("Nonsensical copyin to sbuf %p with a drain", s)); 411 412 if (s->s_error != 0) 413 return (-1); 414 if (len == 0) 415 return (0); 416 if (len > SBUF_FREESPACE(s)) { 417 sbuf_extend(s, len - SBUF_FREESPACE(s)); 418 if (SBUF_FREESPACE(s) < len) 419 len = SBUF_FREESPACE(s); 420 } 421 if (copyin(uaddr, s->s_buf + s->s_len, len) != 0) 422 return (-1); 423 s->s_len += len; 424 425 return (0); 426} 427#endif 428 429/* 430 * Copy a byte string into an sbuf. 431 */ 432int 433sbuf_bcpy(struct sbuf *s, const void *buf, size_t len) 434{ 435 436 assert_sbuf_integrity(s); 437 assert_sbuf_state(s, 0); 438 439 sbuf_clear(s); 440 return (sbuf_bcat(s, buf, len)); 441} 442 443/* 444 * Append a string to an sbuf. 445 */ 446int 447sbuf_cat(struct sbuf *s, const char *str) 448{ 449 450 assert_sbuf_integrity(s); 451 assert_sbuf_state(s, 0); 452 453 if (s->s_error != 0) 454 return (-1); 455 456 while (*str != '\0') { 457 sbuf_put_byte(s, *str++); 458 if (s->s_error != 0) 459 return (-1); 460 } 461 return (0); 462} 463 464#ifdef _KERNEL 465/* 466 * Append a string from userland to an sbuf. 467 */ 468int 469sbuf_copyin(struct sbuf *s, const void *uaddr, size_t len) 470{ 471 size_t done; 472 473 assert_sbuf_integrity(s); 474 assert_sbuf_state(s, 0); 475 KASSERT(s->s_drain_func == NULL, 476 ("Nonsensical copyin to sbuf %p with a drain", s)); 477 478 if (s->s_error != 0) 479 return (-1); 480 481 if (len == 0) 482 len = SBUF_FREESPACE(s); /* XXX return 0? */ 483 if (len > SBUF_FREESPACE(s)) { 484 sbuf_extend(s, len); 485 if (SBUF_FREESPACE(s) < len) 486 len = SBUF_FREESPACE(s); 487 } 488 switch (copyinstr(uaddr, s->s_buf + s->s_len, len + 1, &done)) { 489 case ENAMETOOLONG: 490 s->s_error = ENOMEM; 491 /* fall through */ 492 case 0: 493 s->s_len += done - 1; 494 break; 495 default: 496 return (-1); /* XXX */ 497 } 498 499 return (done); 500} 501#endif 502 503/* 504 * Copy a string into an sbuf. 505 */ 506int 507sbuf_cpy(struct sbuf *s, const char *str) 508{ 509 510 assert_sbuf_integrity(s); 511 assert_sbuf_state(s, 0); 512 513 sbuf_clear(s); 514 return (sbuf_cat(s, str)); 515} 516 517/* 518 * Format the given argument list and append the resulting string to an sbuf. 519 */ 520#ifdef _KERNEL 521 522/* 523 * Append a non-NUL character to an sbuf. This prototype signature is 524 * suitable for use with kvprintf(9). 525 */ 526static void 527sbuf_putc_func(int c, void *arg) 528{ 529 530 if (c != '\0') 531 sbuf_put_byte(arg, c); 532} 533 534int 535sbuf_vprintf(struct sbuf *s, const char *fmt, va_list ap) 536{ 537 538 assert_sbuf_integrity(s); 539 assert_sbuf_state(s, 0); 540 541 KASSERT(fmt != NULL, 542 ("%s called with a NULL format string", __func__)); 543 544 (void)kvprintf(fmt, sbuf_putc_func, s, 10, ap); 545 if (s->s_error != 0) 546 return (-1); 547 return (0); 548} 549#else /* !_KERNEL */ 550int 551sbuf_vprintf(struct sbuf *s, const char *fmt, va_list ap) 552{ 553 va_list ap_copy; 554 int error, len; 555 556 assert_sbuf_integrity(s); 557 assert_sbuf_state(s, 0); 558 559 KASSERT(fmt != NULL, 560 ("%s called with a NULL format string", __func__)); 561 562 if (s->s_error != 0) 563 return (-1); 564 565 /* 566 * For the moment, there is no way to get vsnprintf(3) to hand 567 * back a character at a time, to push everything into 568 * sbuf_putc_func() as was done for the kernel. 569 * 570 * In userspace, while drains are useful, there's generally 571 * not a problem attempting to malloc(3) on out of space. So 572 * expand a userland sbuf if there is not enough room for the 573 * data produced by sbuf_[v]printf(3). 574 */ 575 576 error = 0; 577 do { 578 va_copy(ap_copy, ap); 579 len = vsnprintf(&s->s_buf[s->s_len], SBUF_FREESPACE(s) + 1, 580 fmt, ap_copy); 581 va_end(ap_copy); 582 583 if (SBUF_FREESPACE(s) >= len) 584 break; 585 /* Cannot print with the current available space. */ 586 if (s->s_drain_func != NULL && s->s_len > 0) 587 error = sbuf_drain(s); 588 else 589 error = sbuf_extend(s, len - SBUF_FREESPACE(s)); 590 } while (error == 0); 591 592 /* 593 * s->s_len is the length of the string, without the terminating nul. 594 * When updating s->s_len, we must subtract 1 from the length that 595 * we passed into vsnprintf() because that length includes the 596 * terminating nul. 597 * 598 * vsnprintf() returns the amount that would have been copied, 599 * given sufficient space, so don't over-increment s_len. 600 */ 601 if (SBUF_FREESPACE(s) < len) 602 len = SBUF_FREESPACE(s); 603 s->s_len += len; 604 if (!SBUF_HASROOM(s) && !SBUF_CANEXTEND(s)) 605 s->s_error = ENOMEM; 606 607 KASSERT(s->s_len < s->s_size, 608 ("wrote past end of sbuf (%d >= %d)", s->s_len, s->s_size)); 609 610 if (s->s_error != 0) 611 return (-1); 612 return (0); 613} 614#endif /* _KERNEL */ 615 616/* 617 * Format the given arguments and append the resulting string to an sbuf. 618 */ 619int 620sbuf_printf(struct sbuf *s, const char *fmt, ...) 621{ 622 va_list ap; 623 int result; 624 625 va_start(ap, fmt); 626 result = sbuf_vprintf(s, fmt, ap); 627 va_end(ap); 628 return (result); 629} 630 631/* 632 * Append a character to an sbuf. 633 */ 634int 635sbuf_putc(struct sbuf *s, int c) 636{ 637 638 sbuf_put_byte(s, c); 639 if (s->s_error != 0) 640 return (-1); 641 return (0); 642} 643 644/* 645 * Trim whitespace characters from end of an sbuf. 646 */ 647int 648sbuf_trim(struct sbuf *s) 649{ 650 651 assert_sbuf_integrity(s); 652 assert_sbuf_state(s, 0); 653 KASSERT(s->s_drain_func == NULL, 654 ("%s makes no sense on sbuf %p with drain", __func__, s)); 655 656 if (s->s_error != 0) 657 return (-1); 658 659 while (s->s_len > 0 && isspace(s->s_buf[s->s_len-1])) 660 --s->s_len; 661 662 return (0); 663} 664 665/* 666 * Check if an sbuf has an error. 667 */ 668int 669sbuf_error(const struct sbuf *s) 670{ 671 672 return (s->s_error); 673} 674 675/* 676 * Finish off an sbuf. 677 */ 678int 679sbuf_finish(struct sbuf *s) 680{ 681 682 assert_sbuf_integrity(s); 683 assert_sbuf_state(s, 0); 684 685 if (s->s_drain_func != NULL) { 686 while (s->s_len > 0 && s->s_error == 0) 687 s->s_error = sbuf_drain(s); 688 } 689 s->s_buf[s->s_len] = '\0'; 690 SBUF_SETFLAG(s, SBUF_FINISHED); 691#ifdef _KERNEL 692 return (s->s_error); 693#else 694 errno = s->s_error; 695 if (s->s_error) 696 return (-1); 697 return (0); 698#endif 699} 700 701/* 702 * Return a pointer to the sbuf data. 703 */ 704char * 705sbuf_data(struct sbuf *s) 706{ 707 708 assert_sbuf_integrity(s); 709 assert_sbuf_state(s, SBUF_FINISHED); 710 KASSERT(s->s_drain_func == NULL, 711 ("%s makes no sense on sbuf %p with drain", __func__, s)); 712 713 return (s->s_buf); 714} 715 716/* 717 * Return the length of the sbuf data. 718 */ 719ssize_t 720sbuf_len(struct sbuf *s) 721{ 722 723 assert_sbuf_integrity(s); 724 /* don't care if it's finished or not */ 725 KASSERT(s->s_drain_func == NULL, 726 ("%s makes no sense on sbuf %p with drain", __func__, s)); 727 728 if (s->s_error != 0) 729 return (-1); 730 return (s->s_len); 731} 732 733/* 734 * Clear an sbuf, free its buffer if necessary. 735 */ 736void 737sbuf_delete(struct sbuf *s) 738{ 739 int isdyn; 740 741 assert_sbuf_integrity(s); 742 /* don't care if it's finished or not */ 743 744 if (SBUF_ISDYNAMIC(s)) 745 SBFREE(s->s_buf); 746 isdyn = SBUF_ISDYNSTRUCT(s); 747 memset(s, 0, sizeof(*s)); 748 if (isdyn) 749 SBFREE(s); 750} 751 752/* 753 * Check if an sbuf has been finished. 754 */ 755int 756sbuf_done(const struct sbuf *s) 757{ 758 759 return (SBUF_ISFINISHED(s)); 760} 761