1// SPDX-License-Identifier: GPL-2.0 2/* 3 * linux/fs/seq_file.c 4 * 5 * helper functions for making synthetic files from sequences of records. 6 * initial implementation -- AV, Oct 2001. 7 */ 8 9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 10 11#include <linux/cache.h> 12#include <linux/fs.h> 13#include <linux/export.h> 14#include <linux/seq_file.h> 15#include <linux/vmalloc.h> 16#include <linux/slab.h> 17#include <linux/cred.h> 18#include <linux/mm.h> 19#include <linux/printk.h> 20#include <linux/string_helpers.h> 21#include <linux/uio.h> 22 23#include <linux/uaccess.h> 24#include <asm/page.h> 25 26static struct kmem_cache *seq_file_cache __ro_after_init; 27 28static void seq_set_overflow(struct seq_file *m) 29{ 30 m->count = m->size; 31} 32 33static void *seq_buf_alloc(unsigned long size) 34{ 35 if (unlikely(size > MAX_RW_COUNT)) 36 return NULL; 37 38 return kvmalloc(size, GFP_KERNEL_ACCOUNT); 39} 40 41/** 42 * seq_open - initialize sequential file 43 * @file: file we initialize 44 * @op: method table describing the sequence 45 * 46 * seq_open() sets @file, associating it with a sequence described 47 * by @op. @op->start() sets the iterator up and returns the first 48 * element of sequence. @op->stop() shuts it down. @op->next() 49 * returns the next element of sequence. @op->show() prints element 50 * into the buffer. In case of error ->start() and ->next() return 51 * ERR_PTR(error). In the end of sequence they return %NULL. ->show() 52 * returns 0 in case of success and negative number in case of error. 53 * Returning SEQ_SKIP means "discard this element and move on". 54 * Note: seq_open() will allocate a struct seq_file and store its 55 * pointer in @file->private_data. This pointer should not be modified. 56 */ 57int seq_open(struct file *file, const struct seq_operations *op) 58{ 59 struct seq_file *p; 60 61 WARN_ON(file->private_data); 62 63 p = kmem_cache_zalloc(seq_file_cache, GFP_KERNEL); 64 if (!p) 65 return -ENOMEM; 66 67 file->private_data = p; 68 69 mutex_init(&p->lock); 70 p->op = op; 71 72 // No refcounting: the lifetime of 'p' is constrained 73 // to the lifetime of the file. 74 p->file = file; 75 76 /* 77 * seq_files support lseek() and pread(). They do not implement 78 * write() at all, but we clear FMODE_PWRITE here for historical 79 * reasons. 80 * 81 * If a client of seq_files a) implements file.write() and b) wishes to 82 * support pwrite() then that client will need to implement its own 83 * file.open() which calls seq_open() and then sets FMODE_PWRITE. 84 */ 85 file->f_mode &= ~FMODE_PWRITE; 86 return 0; 87} 88EXPORT_SYMBOL(seq_open); 89 90static int traverse(struct seq_file *m, loff_t offset) 91{ 92 loff_t pos = 0; 93 int error = 0; 94 void *p; 95 96 m->index = 0; 97 m->count = m->from = 0; 98 if (!offset) 99 return 0; 100 101 if (!m->buf) { 102 m->buf = seq_buf_alloc(m->size = PAGE_SIZE); 103 if (!m->buf) 104 return -ENOMEM; 105 } 106 p = m->op->start(m, &m->index); 107 while (p) { 108 error = PTR_ERR(p); 109 if (IS_ERR(p)) 110 break; 111 error = m->op->show(m, p); 112 if (error < 0) 113 break; 114 if (unlikely(error)) { 115 error = 0; 116 m->count = 0; 117 } 118 if (seq_has_overflowed(m)) 119 goto Eoverflow; 120 p = m->op->next(m, p, &m->index); 121 if (pos + m->count > offset) { 122 m->from = offset - pos; 123 m->count -= m->from; 124 break; 125 } 126 pos += m->count; 127 m->count = 0; 128 if (pos == offset) 129 break; 130 } 131 m->op->stop(m, p); 132 return error; 133 134Eoverflow: 135 m->op->stop(m, p); 136 kvfree(m->buf); 137 m->count = 0; 138 m->buf = seq_buf_alloc(m->size <<= 1); 139 return !m->buf ? -ENOMEM : -EAGAIN; 140} 141 142/** 143 * seq_read - ->read() method for sequential files. 144 * @file: the file to read from 145 * @buf: the buffer to read to 146 * @size: the maximum number of bytes to read 147 * @ppos: the current position in the file 148 * 149 * Ready-made ->f_op->read() 150 */ 151ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) 152{ 153 struct iovec iov = { .iov_base = buf, .iov_len = size}; 154 struct kiocb kiocb; 155 struct iov_iter iter; 156 ssize_t ret; 157 158 init_sync_kiocb(&kiocb, file); 159 iov_iter_init(&iter, ITER_DEST, &iov, 1, size); 160 161 kiocb.ki_pos = *ppos; 162 ret = seq_read_iter(&kiocb, &iter); 163 *ppos = kiocb.ki_pos; 164 return ret; 165} 166EXPORT_SYMBOL(seq_read); 167 168/* 169 * Ready-made ->f_op->read_iter() 170 */ 171ssize_t seq_read_iter(struct kiocb *iocb, struct iov_iter *iter) 172{ 173 struct seq_file *m = iocb->ki_filp->private_data; 174 size_t copied = 0; 175 size_t n; 176 void *p; 177 int err = 0; 178 179 if (!iov_iter_count(iter)) 180 return 0; 181 182 mutex_lock(&m->lock); 183 184 /* 185 * if request is to read from zero offset, reset iterator to first 186 * record as it might have been already advanced by previous requests 187 */ 188 if (iocb->ki_pos == 0) { 189 m->index = 0; 190 m->count = 0; 191 } 192 193 /* Don't assume ki_pos is where we left it */ 194 if (unlikely(iocb->ki_pos != m->read_pos)) { 195 while ((err = traverse(m, iocb->ki_pos)) == -EAGAIN) 196 ; 197 if (err) { 198 /* With prejudice... */ 199 m->read_pos = 0; 200 m->index = 0; 201 m->count = 0; 202 goto Done; 203 } else { 204 m->read_pos = iocb->ki_pos; 205 } 206 } 207 208 /* grab buffer if we didn't have one */ 209 if (!m->buf) { 210 m->buf = seq_buf_alloc(m->size = PAGE_SIZE); 211 if (!m->buf) 212 goto Enomem; 213 } 214 // something left in the buffer - copy it out first 215 if (m->count) { 216 n = copy_to_iter(m->buf + m->from, m->count, iter); 217 m->count -= n; 218 m->from += n; 219 copied += n; 220 if (m->count) // hadn't managed to copy everything 221 goto Done; 222 } 223 // get a non-empty record in the buffer 224 m->from = 0; 225 p = m->op->start(m, &m->index); 226 while (1) { 227 err = PTR_ERR(p); 228 if (!p || IS_ERR(p)) // EOF or an error 229 break; 230 err = m->op->show(m, p); 231 if (err < 0) // hard error 232 break; 233 if (unlikely(err)) // ->show() says "skip it" 234 m->count = 0; 235 if (unlikely(!m->count)) { // empty record 236 p = m->op->next(m, p, &m->index); 237 continue; 238 } 239 if (!seq_has_overflowed(m)) // got it 240 goto Fill; 241 // need a bigger buffer 242 m->op->stop(m, p); 243 kvfree(m->buf); 244 m->count = 0; 245 m->buf = seq_buf_alloc(m->size <<= 1); 246 if (!m->buf) 247 goto Enomem; 248 p = m->op->start(m, &m->index); 249 } 250 // EOF or an error 251 m->op->stop(m, p); 252 m->count = 0; 253 goto Done; 254Fill: 255 // one non-empty record is in the buffer; if they want more, 256 // try to fit more in, but in any case we need to advance 257 // the iterator once for every record shown. 258 while (1) { 259 size_t offs = m->count; 260 loff_t pos = m->index; 261 262 p = m->op->next(m, p, &m->index); 263 if (pos == m->index) { 264 pr_info_ratelimited("buggy .next function %ps did not update position index\n", 265 m->op->next); 266 m->index++; 267 } 268 if (!p || IS_ERR(p)) // no next record for us 269 break; 270 if (m->count >= iov_iter_count(iter)) 271 break; 272 err = m->op->show(m, p); 273 if (err > 0) { // ->show() says "skip it" 274 m->count = offs; 275 } else if (err || seq_has_overflowed(m)) { 276 m->count = offs; 277 break; 278 } 279 } 280 m->op->stop(m, p); 281 n = copy_to_iter(m->buf, m->count, iter); 282 copied += n; 283 m->count -= n; 284 m->from = n; 285Done: 286 if (unlikely(!copied)) { 287 copied = m->count ? -EFAULT : err; 288 } else { 289 iocb->ki_pos += copied; 290 m->read_pos += copied; 291 } 292 mutex_unlock(&m->lock); 293 return copied; 294Enomem: 295 err = -ENOMEM; 296 goto Done; 297} 298EXPORT_SYMBOL(seq_read_iter); 299 300/** 301 * seq_lseek - ->llseek() method for sequential files. 302 * @file: the file in question 303 * @offset: new position 304 * @whence: 0 for absolute, 1 for relative position 305 * 306 * Ready-made ->f_op->llseek() 307 */ 308loff_t seq_lseek(struct file *file, loff_t offset, int whence) 309{ 310 struct seq_file *m = file->private_data; 311 loff_t retval = -EINVAL; 312 313 mutex_lock(&m->lock); 314 switch (whence) { 315 case SEEK_CUR: 316 offset += file->f_pos; 317 fallthrough; 318 case SEEK_SET: 319 if (offset < 0) 320 break; 321 retval = offset; 322 if (offset != m->read_pos) { 323 while ((retval = traverse(m, offset)) == -EAGAIN) 324 ; 325 if (retval) { 326 /* with extreme prejudice... */ 327 file->f_pos = 0; 328 m->read_pos = 0; 329 m->index = 0; 330 m->count = 0; 331 } else { 332 m->read_pos = offset; 333 retval = file->f_pos = offset; 334 } 335 } else { 336 file->f_pos = offset; 337 } 338 } 339 mutex_unlock(&m->lock); 340 return retval; 341} 342EXPORT_SYMBOL(seq_lseek); 343 344/** 345 * seq_release - free the structures associated with sequential file. 346 * @file: file in question 347 * @inode: its inode 348 * 349 * Frees the structures associated with sequential file; can be used 350 * as ->f_op->release() if you don't have private data to destroy. 351 */ 352int seq_release(struct inode *inode, struct file *file) 353{ 354 struct seq_file *m = file->private_data; 355 kvfree(m->buf); 356 kmem_cache_free(seq_file_cache, m); 357 return 0; 358} 359EXPORT_SYMBOL(seq_release); 360 361/** 362 * seq_escape_mem - print data into buffer, escaping some characters 363 * @m: target buffer 364 * @src: source buffer 365 * @len: size of source buffer 366 * @flags: flags to pass to string_escape_mem() 367 * @esc: set of characters that need escaping 368 * 369 * Puts data into buffer, replacing each occurrence of character from 370 * given class (defined by @flags and @esc) with printable escaped sequence. 371 * 372 * Use seq_has_overflowed() to check for errors. 373 */ 374void seq_escape_mem(struct seq_file *m, const char *src, size_t len, 375 unsigned int flags, const char *esc) 376{ 377 char *buf; 378 size_t size = seq_get_buf(m, &buf); 379 int ret; 380 381 ret = string_escape_mem(src, len, buf, size, flags, esc); 382 seq_commit(m, ret < size ? ret : -1); 383} 384EXPORT_SYMBOL(seq_escape_mem); 385 386void seq_vprintf(struct seq_file *m, const char *f, va_list args) 387{ 388 int len; 389 390 if (m->count < m->size) { 391 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args); 392 if (m->count + len < m->size) { 393 m->count += len; 394 return; 395 } 396 } 397 seq_set_overflow(m); 398} 399EXPORT_SYMBOL(seq_vprintf); 400 401void seq_printf(struct seq_file *m, const char *f, ...) 402{ 403 va_list args; 404 405 va_start(args, f); 406 seq_vprintf(m, f, args); 407 va_end(args); 408} 409EXPORT_SYMBOL(seq_printf); 410 411#ifdef CONFIG_BINARY_PRINTF 412void seq_bprintf(struct seq_file *m, const char *f, const u32 *binary) 413{ 414 int len; 415 416 if (m->count < m->size) { 417 len = bstr_printf(m->buf + m->count, m->size - m->count, f, 418 binary); 419 if (m->count + len < m->size) { 420 m->count += len; 421 return; 422 } 423 } 424 seq_set_overflow(m); 425} 426EXPORT_SYMBOL(seq_bprintf); 427#endif /* CONFIG_BINARY_PRINTF */ 428 429/** 430 * mangle_path - mangle and copy path to buffer beginning 431 * @s: buffer start 432 * @p: beginning of path in above buffer 433 * @esc: set of characters that need escaping 434 * 435 * Copy the path from @p to @s, replacing each occurrence of character from 436 * @esc with usual octal escape. 437 * Returns pointer past last written character in @s, or NULL in case of 438 * failure. 439 */ 440char *mangle_path(char *s, const char *p, const char *esc) 441{ 442 while (s <= p) { 443 char c = *p++; 444 if (!c) { 445 return s; 446 } else if (!strchr(esc, c)) { 447 *s++ = c; 448 } else if (s + 4 > p) { 449 break; 450 } else { 451 *s++ = '\\'; 452 *s++ = '0' + ((c & 0300) >> 6); 453 *s++ = '0' + ((c & 070) >> 3); 454 *s++ = '0' + (c & 07); 455 } 456 } 457 return NULL; 458} 459EXPORT_SYMBOL(mangle_path); 460 461/** 462 * seq_path - seq_file interface to print a pathname 463 * @m: the seq_file handle 464 * @path: the struct path to print 465 * @esc: set of characters to escape in the output 466 * 467 * return the absolute path of 'path', as represented by the 468 * dentry / mnt pair in the path parameter. 469 */ 470int seq_path(struct seq_file *m, const struct path *path, const char *esc) 471{ 472 char *buf; 473 size_t size = seq_get_buf(m, &buf); 474 int res = -1; 475 476 if (size) { 477 char *p = d_path(path, buf, size); 478 if (!IS_ERR(p)) { 479 char *end = mangle_path(buf, p, esc); 480 if (end) 481 res = end - buf; 482 } 483 } 484 seq_commit(m, res); 485 486 return res; 487} 488EXPORT_SYMBOL(seq_path); 489 490/** 491 * seq_file_path - seq_file interface to print a pathname of a file 492 * @m: the seq_file handle 493 * @file: the struct file to print 494 * @esc: set of characters to escape in the output 495 * 496 * return the absolute path to the file. 497 */ 498int seq_file_path(struct seq_file *m, struct file *file, const char *esc) 499{ 500 return seq_path(m, &file->f_path, esc); 501} 502EXPORT_SYMBOL(seq_file_path); 503 504/* 505 * Same as seq_path, but relative to supplied root. 506 */ 507int seq_path_root(struct seq_file *m, const struct path *path, 508 const struct path *root, const char *esc) 509{ 510 char *buf; 511 size_t size = seq_get_buf(m, &buf); 512 int res = -ENAMETOOLONG; 513 514 if (size) { 515 char *p; 516 517 p = __d_path(path, root, buf, size); 518 if (!p) 519 return SEQ_SKIP; 520 res = PTR_ERR(p); 521 if (!IS_ERR(p)) { 522 char *end = mangle_path(buf, p, esc); 523 if (end) 524 res = end - buf; 525 else 526 res = -ENAMETOOLONG; 527 } 528 } 529 seq_commit(m, res); 530 531 return res < 0 && res != -ENAMETOOLONG ? res : 0; 532} 533 534/* 535 * returns the path of the 'dentry' from the root of its filesystem. 536 */ 537int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc) 538{ 539 char *buf; 540 size_t size = seq_get_buf(m, &buf); 541 int res = -1; 542 543 if (size) { 544 char *p = dentry_path(dentry, buf, size); 545 if (!IS_ERR(p)) { 546 char *end = mangle_path(buf, p, esc); 547 if (end) 548 res = end - buf; 549 } 550 } 551 seq_commit(m, res); 552 553 return res; 554} 555EXPORT_SYMBOL(seq_dentry); 556 557void *single_start(struct seq_file *p, loff_t *pos) 558{ 559 return *pos ? NULL : SEQ_START_TOKEN; 560} 561 562static void *single_next(struct seq_file *p, void *v, loff_t *pos) 563{ 564 ++*pos; 565 return NULL; 566} 567 568static void single_stop(struct seq_file *p, void *v) 569{ 570} 571 572int single_open(struct file *file, int (*show)(struct seq_file *, void *), 573 void *data) 574{ 575 struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL_ACCOUNT); 576 int res = -ENOMEM; 577 578 if (op) { 579 op->start = single_start; 580 op->next = single_next; 581 op->stop = single_stop; 582 op->show = show; 583 res = seq_open(file, op); 584 if (!res) 585 ((struct seq_file *)file->private_data)->private = data; 586 else 587 kfree(op); 588 } 589 return res; 590} 591EXPORT_SYMBOL(single_open); 592 593int single_open_size(struct file *file, int (*show)(struct seq_file *, void *), 594 void *data, size_t size) 595{ 596 char *buf = seq_buf_alloc(size); 597 int ret; 598 if (!buf) 599 return -ENOMEM; 600 ret = single_open(file, show, data); 601 if (ret) { 602 kvfree(buf); 603 return ret; 604 } 605 ((struct seq_file *)file->private_data)->buf = buf; 606 ((struct seq_file *)file->private_data)->size = size; 607 return 0; 608} 609EXPORT_SYMBOL(single_open_size); 610 611int single_release(struct inode *inode, struct file *file) 612{ 613 const struct seq_operations *op = ((struct seq_file *)file->private_data)->op; 614 int res = seq_release(inode, file); 615 kfree(op); 616 return res; 617} 618EXPORT_SYMBOL(single_release); 619 620int seq_release_private(struct inode *inode, struct file *file) 621{ 622 struct seq_file *seq = file->private_data; 623 624 kfree(seq->private); 625 seq->private = NULL; 626 return seq_release(inode, file); 627} 628EXPORT_SYMBOL(seq_release_private); 629 630void *__seq_open_private(struct file *f, const struct seq_operations *ops, 631 int psize) 632{ 633 int rc; 634 void *private; 635 struct seq_file *seq; 636 637 private = kzalloc(psize, GFP_KERNEL_ACCOUNT); 638 if (private == NULL) 639 goto out; 640 641 rc = seq_open(f, ops); 642 if (rc < 0) 643 goto out_free; 644 645 seq = f->private_data; 646 seq->private = private; 647 return private; 648 649out_free: 650 kfree(private); 651out: 652 return NULL; 653} 654EXPORT_SYMBOL(__seq_open_private); 655 656int seq_open_private(struct file *filp, const struct seq_operations *ops, 657 int psize) 658{ 659 return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM; 660} 661EXPORT_SYMBOL(seq_open_private); 662 663void seq_putc(struct seq_file *m, char c) 664{ 665 if (m->count >= m->size) 666 return; 667 668 m->buf[m->count++] = c; 669} 670EXPORT_SYMBOL(seq_putc); 671 672void seq_puts(struct seq_file *m, const char *s) 673{ 674 int len = strlen(s); 675 676 if (m->count + len >= m->size) { 677 seq_set_overflow(m); 678 return; 679 } 680 memcpy(m->buf + m->count, s, len); 681 m->count += len; 682} 683EXPORT_SYMBOL(seq_puts); 684 685/** 686 * seq_put_decimal_ull_width - A helper routine for putting decimal numbers 687 * without rich format of printf(). 688 * only 'unsigned long long' is supported. 689 * @m: seq_file identifying the buffer to which data should be written 690 * @delimiter: a string which is printed before the number 691 * @num: the number 692 * @width: a minimum field width 693 * 694 * This routine will put strlen(delimiter) + number into seq_filed. 695 * This routine is very quick when you show lots of numbers. 696 * In usual cases, it will be better to use seq_printf(). It's easier to read. 697 */ 698void seq_put_decimal_ull_width(struct seq_file *m, const char *delimiter, 699 unsigned long long num, unsigned int width) 700{ 701 int len; 702 703 if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */ 704 goto overflow; 705 706 if (delimiter && delimiter[0]) { 707 if (delimiter[1] == 0) 708 seq_putc(m, delimiter[0]); 709 else 710 seq_puts(m, delimiter); 711 } 712 713 if (!width) 714 width = 1; 715 716 if (m->count + width >= m->size) 717 goto overflow; 718 719 len = num_to_str(m->buf + m->count, m->size - m->count, num, width); 720 if (!len) 721 goto overflow; 722 723 m->count += len; 724 return; 725 726overflow: 727 seq_set_overflow(m); 728} 729 730void seq_put_decimal_ull(struct seq_file *m, const char *delimiter, 731 unsigned long long num) 732{ 733 return seq_put_decimal_ull_width(m, delimiter, num, 0); 734} 735EXPORT_SYMBOL(seq_put_decimal_ull); 736 737/** 738 * seq_put_hex_ll - put a number in hexadecimal notation 739 * @m: seq_file identifying the buffer to which data should be written 740 * @delimiter: a string which is printed before the number 741 * @v: the number 742 * @width: a minimum field width 743 * 744 * seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "%08llx", v) 745 * 746 * This routine is very quick when you show lots of numbers. 747 * In usual cases, it will be better to use seq_printf(). It's easier to read. 748 */ 749void seq_put_hex_ll(struct seq_file *m, const char *delimiter, 750 unsigned long long v, unsigned int width) 751{ 752 unsigned int len; 753 int i; 754 755 if (delimiter && delimiter[0]) { 756 if (delimiter[1] == 0) 757 seq_putc(m, delimiter[0]); 758 else 759 seq_puts(m, delimiter); 760 } 761 762 /* If x is 0, the result of __builtin_clzll is undefined */ 763 if (v == 0) 764 len = 1; 765 else 766 len = (sizeof(v) * 8 - __builtin_clzll(v) + 3) / 4; 767 768 if (len < width) 769 len = width; 770 771 if (m->count + len > m->size) { 772 seq_set_overflow(m); 773 return; 774 } 775 776 for (i = len - 1; i >= 0; i--) { 777 m->buf[m->count + i] = hex_asc[0xf & v]; 778 v = v >> 4; 779 } 780 m->count += len; 781} 782 783void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num) 784{ 785 int len; 786 787 if (m->count + 3 >= m->size) /* we'll write 2 bytes at least */ 788 goto overflow; 789 790 if (delimiter && delimiter[0]) { 791 if (delimiter[1] == 0) 792 seq_putc(m, delimiter[0]); 793 else 794 seq_puts(m, delimiter); 795 } 796 797 if (m->count + 2 >= m->size) 798 goto overflow; 799 800 if (num < 0) { 801 m->buf[m->count++] = '-'; 802 num = -num; 803 } 804 805 if (num < 10) { 806 m->buf[m->count++] = num + '0'; 807 return; 808 } 809 810 len = num_to_str(m->buf + m->count, m->size - m->count, num, 0); 811 if (!len) 812 goto overflow; 813 814 m->count += len; 815 return; 816 817overflow: 818 seq_set_overflow(m); 819} 820EXPORT_SYMBOL(seq_put_decimal_ll); 821 822/** 823 * seq_write - write arbitrary data to buffer 824 * @seq: seq_file identifying the buffer to which data should be written 825 * @data: data address 826 * @len: number of bytes 827 * 828 * Return 0 on success, non-zero otherwise. 829 */ 830int seq_write(struct seq_file *seq, const void *data, size_t len) 831{ 832 if (seq->count + len < seq->size) { 833 memcpy(seq->buf + seq->count, data, len); 834 seq->count += len; 835 return 0; 836 } 837 seq_set_overflow(seq); 838 return -1; 839} 840EXPORT_SYMBOL(seq_write); 841 842/** 843 * seq_pad - write padding spaces to buffer 844 * @m: seq_file identifying the buffer to which data should be written 845 * @c: the byte to append after padding if non-zero 846 */ 847void seq_pad(struct seq_file *m, char c) 848{ 849 int size = m->pad_until - m->count; 850 if (size > 0) { 851 if (size + m->count > m->size) { 852 seq_set_overflow(m); 853 return; 854 } 855 memset(m->buf + m->count, ' ', size); 856 m->count += size; 857 } 858 if (c) 859 seq_putc(m, c); 860} 861EXPORT_SYMBOL(seq_pad); 862 863/* A complete analogue of print_hex_dump() */ 864void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type, 865 int rowsize, int groupsize, const void *buf, size_t len, 866 bool ascii) 867{ 868 const u8 *ptr = buf; 869 int i, linelen, remaining = len; 870 char *buffer; 871 size_t size; 872 int ret; 873 874 if (rowsize != 16 && rowsize != 32) 875 rowsize = 16; 876 877 for (i = 0; i < len && !seq_has_overflowed(m); i += rowsize) { 878 linelen = min(remaining, rowsize); 879 remaining -= rowsize; 880 881 switch (prefix_type) { 882 case DUMP_PREFIX_ADDRESS: 883 seq_printf(m, "%s%p: ", prefix_str, ptr + i); 884 break; 885 case DUMP_PREFIX_OFFSET: 886 seq_printf(m, "%s%.8x: ", prefix_str, i); 887 break; 888 default: 889 seq_printf(m, "%s", prefix_str); 890 break; 891 } 892 893 size = seq_get_buf(m, &buffer); 894 ret = hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize, 895 buffer, size, ascii); 896 seq_commit(m, ret < size ? ret : -1); 897 898 seq_putc(m, '\n'); 899 } 900} 901EXPORT_SYMBOL(seq_hex_dump); 902 903struct list_head *seq_list_start(struct list_head *head, loff_t pos) 904{ 905 struct list_head *lh; 906 907 list_for_each(lh, head) 908 if (pos-- == 0) 909 return lh; 910 911 return NULL; 912} 913EXPORT_SYMBOL(seq_list_start); 914 915struct list_head *seq_list_start_head(struct list_head *head, loff_t pos) 916{ 917 if (!pos) 918 return head; 919 920 return seq_list_start(head, pos - 1); 921} 922EXPORT_SYMBOL(seq_list_start_head); 923 924struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos) 925{ 926 struct list_head *lh; 927 928 lh = ((struct list_head *)v)->next; 929 ++*ppos; 930 return lh == head ? NULL : lh; 931} 932EXPORT_SYMBOL(seq_list_next); 933 934struct list_head *seq_list_start_rcu(struct list_head *head, loff_t pos) 935{ 936 struct list_head *lh; 937 938 list_for_each_rcu(lh, head) 939 if (pos-- == 0) 940 return lh; 941 942 return NULL; 943} 944EXPORT_SYMBOL(seq_list_start_rcu); 945 946struct list_head *seq_list_start_head_rcu(struct list_head *head, loff_t pos) 947{ 948 if (!pos) 949 return head; 950 951 return seq_list_start_rcu(head, pos - 1); 952} 953EXPORT_SYMBOL(seq_list_start_head_rcu); 954 955struct list_head *seq_list_next_rcu(void *v, struct list_head *head, 956 loff_t *ppos) 957{ 958 struct list_head *lh; 959 960 lh = list_next_rcu((struct list_head *)v); 961 ++*ppos; 962 return lh == head ? NULL : lh; 963} 964EXPORT_SYMBOL(seq_list_next_rcu); 965 966/** 967 * seq_hlist_start - start an iteration of a hlist 968 * @head: the head of the hlist 969 * @pos: the start position of the sequence 970 * 971 * Called at seq_file->op->start(). 972 */ 973struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos) 974{ 975 struct hlist_node *node; 976 977 hlist_for_each(node, head) 978 if (pos-- == 0) 979 return node; 980 return NULL; 981} 982EXPORT_SYMBOL(seq_hlist_start); 983 984/** 985 * seq_hlist_start_head - start an iteration of a hlist 986 * @head: the head of the hlist 987 * @pos: the start position of the sequence 988 * 989 * Called at seq_file->op->start(). Call this function if you want to 990 * print a header at the top of the output. 991 */ 992struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos) 993{ 994 if (!pos) 995 return SEQ_START_TOKEN; 996 997 return seq_hlist_start(head, pos - 1); 998} 999EXPORT_SYMBOL(seq_hlist_start_head); 1000 1001/** 1002 * seq_hlist_next - move to the next position of the hlist 1003 * @v: the current iterator 1004 * @head: the head of the hlist 1005 * @ppos: the current position 1006 * 1007 * Called at seq_file->op->next(). 1008 */ 1009struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head, 1010 loff_t *ppos) 1011{ 1012 struct hlist_node *node = v; 1013 1014 ++*ppos; 1015 if (v == SEQ_START_TOKEN) 1016 return head->first; 1017 else 1018 return node->next; 1019} 1020EXPORT_SYMBOL(seq_hlist_next); 1021 1022/** 1023 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU 1024 * @head: the head of the hlist 1025 * @pos: the start position of the sequence 1026 * 1027 * Called at seq_file->op->start(). 1028 * 1029 * This list-traversal primitive may safely run concurrently with 1030 * the _rcu list-mutation primitives such as hlist_add_head_rcu() 1031 * as long as the traversal is guarded by rcu_read_lock(). 1032 */ 1033struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head, 1034 loff_t pos) 1035{ 1036 struct hlist_node *node; 1037 1038 __hlist_for_each_rcu(node, head) 1039 if (pos-- == 0) 1040 return node; 1041 return NULL; 1042} 1043EXPORT_SYMBOL(seq_hlist_start_rcu); 1044 1045/** 1046 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU 1047 * @head: the head of the hlist 1048 * @pos: the start position of the sequence 1049 * 1050 * Called at seq_file->op->start(). Call this function if you want to 1051 * print a header at the top of the output. 1052 * 1053 * This list-traversal primitive may safely run concurrently with 1054 * the _rcu list-mutation primitives such as hlist_add_head_rcu() 1055 * as long as the traversal is guarded by rcu_read_lock(). 1056 */ 1057struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head, 1058 loff_t pos) 1059{ 1060 if (!pos) 1061 return SEQ_START_TOKEN; 1062 1063 return seq_hlist_start_rcu(head, pos - 1); 1064} 1065EXPORT_SYMBOL(seq_hlist_start_head_rcu); 1066 1067/** 1068 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU 1069 * @v: the current iterator 1070 * @head: the head of the hlist 1071 * @ppos: the current position 1072 * 1073 * Called at seq_file->op->next(). 1074 * 1075 * This list-traversal primitive may safely run concurrently with 1076 * the _rcu list-mutation primitives such as hlist_add_head_rcu() 1077 * as long as the traversal is guarded by rcu_read_lock(). 1078 */ 1079struct hlist_node *seq_hlist_next_rcu(void *v, 1080 struct hlist_head *head, 1081 loff_t *ppos) 1082{ 1083 struct hlist_node *node = v; 1084 1085 ++*ppos; 1086 if (v == SEQ_START_TOKEN) 1087 return rcu_dereference(head->first); 1088 else 1089 return rcu_dereference(node->next); 1090} 1091EXPORT_SYMBOL(seq_hlist_next_rcu); 1092 1093/** 1094 * seq_hlist_start_percpu - start an iteration of a percpu hlist array 1095 * @head: pointer to percpu array of struct hlist_heads 1096 * @cpu: pointer to cpu "cursor" 1097 * @pos: start position of sequence 1098 * 1099 * Called at seq_file->op->start(). 1100 */ 1101struct hlist_node * 1102seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos) 1103{ 1104 struct hlist_node *node; 1105 1106 for_each_possible_cpu(*cpu) { 1107 hlist_for_each(node, per_cpu_ptr(head, *cpu)) { 1108 if (pos-- == 0) 1109 return node; 1110 } 1111 } 1112 return NULL; 1113} 1114EXPORT_SYMBOL(seq_hlist_start_percpu); 1115 1116/** 1117 * seq_hlist_next_percpu - move to the next position of the percpu hlist array 1118 * @v: pointer to current hlist_node 1119 * @head: pointer to percpu array of struct hlist_heads 1120 * @cpu: pointer to cpu "cursor" 1121 * @pos: start position of sequence 1122 * 1123 * Called at seq_file->op->next(). 1124 */ 1125struct hlist_node * 1126seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head, 1127 int *cpu, loff_t *pos) 1128{ 1129 struct hlist_node *node = v; 1130 1131 ++*pos; 1132 1133 if (node->next) 1134 return node->next; 1135 1136 for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids; 1137 *cpu = cpumask_next(*cpu, cpu_possible_mask)) { 1138 struct hlist_head *bucket = per_cpu_ptr(head, *cpu); 1139 1140 if (!hlist_empty(bucket)) 1141 return bucket->first; 1142 } 1143 return NULL; 1144} 1145EXPORT_SYMBOL(seq_hlist_next_percpu); 1146 1147void __init seq_file_init(void) 1148{ 1149 seq_file_cache = KMEM_CACHE(seq_file, SLAB_ACCOUNT|SLAB_PANIC); 1150} 1151