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
26 static struct kmem_cache *seq_file_cache __ro_after_init;
27
28 static void seq_set_overflow(struct seq_file *m)
29 {
30 m->count = m->size;
31 }
32
33 static 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 */
57 int 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 }
88 EXPORT_SYMBOL(seq_open);
89
90 static 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
134 Eoverflow:
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 */
151 ssize_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 }
166 EXPORT_SYMBOL(seq_read);
167
168 /*
169 * Ready-made ->f_op->read_iter()
170 */
171 ssize_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;
254 Fill:
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;
285 Done:
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;
294 Enomem:
295 err = -ENOMEM;
296 goto Done;
297 }
298 EXPORT_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 */
308 loff_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 }
342 EXPORT_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 */
352 int 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 }
359 EXPORT_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 */
374 void 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 }
384 EXPORT_SYMBOL(seq_escape_mem);
385
386 void 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 }
399 EXPORT_SYMBOL(seq_vprintf);
400
401 void 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 }
409 EXPORT_SYMBOL(seq_printf);
410
411 #ifdef CONFIG_BINARY_PRINTF
412 void 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 }
426 EXPORT_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 */
440 char *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++ = '' + ((c & 0300) >> 6);
453 *s++ = '' + ((c & 070) >> 3);
454 *s++ = '' + (c & 07);
455 }
456 }
457 return NULL;
458 }
459 EXPORT_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 */
470 int 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 }
488 EXPORT_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 */
498 int seq_file_path(struct seq_file *m, struct file *file, const char *esc)
499 {
500 return seq_path(m, &file->f_path, esc);
501 }
502 EXPORT_SYMBOL(seq_file_path);
503
504 /*
505 * Same as seq_path, but relative to supplied root.
506 */
507 int 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 */
537 int 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 }
555 EXPORT_SYMBOL(seq_dentry);
556
557 void *single_start(struct seq_file *p, loff_t *pos)
558 {
559 return *pos ? NULL : SEQ_START_TOKEN;
560 }
561
562 static void *single_next(struct seq_file *p, void *v, loff_t *pos)
563 {
564 ++*pos;
565 return NULL;
566 }
567
568 static void single_stop(struct seq_file *p, void *v)
569 {
570 }
571
572 int 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 }
591 EXPORT_SYMBOL(single_open);
592
593 int 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 }
609 EXPORT_SYMBOL(single_open_size);
610
611 int 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 }
618 EXPORT_SYMBOL(single_release);
619
620 int 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 }
628 EXPORT_SYMBOL(seq_release_private);
629
630 void *__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
649 out_free:
650 kfree(private);
651 out:
652 return NULL;
653 }
654 EXPORT_SYMBOL(__seq_open_private);
655
656 int 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 }
661 EXPORT_SYMBOL(seq_open_private);
662
663 void 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 }
670 EXPORT_SYMBOL(seq_putc);
671
672 void __seq_puts(struct seq_file *m, const char *s)
673 {
674 seq_write(m, s, strlen(s));
675 }
676 EXPORT_SYMBOL(__seq_puts);
677
678 /**
679 * seq_put_decimal_ull_width - A helper routine for putting decimal numbers
680 * without rich format of printf().
681 * only 'unsigned long long' is supported.
682 * @m: seq_file identifying the buffer to which data should be written
683 * @delimiter: a string which is printed before the number
684 * @num: the number
685 * @width: a minimum field width
686 *
687 * This routine will put strlen(delimiter) + number into seq_filed.
688 * This routine is very quick when you show lots of numbers.
689 * In usual cases, it will be better to use seq_printf(). It's easier to read.
690 */
691 void seq_put_decimal_ull_width(struct seq_file *m, const char *delimiter,
692 unsigned long long num, unsigned int width)
693 {
694 int len;
695
696 if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
697 goto overflow;
698
699 if (delimiter && delimiter[0]) {
700 if (delimiter[1] == 0)
701 seq_putc(m, delimiter[0]);
702 else
703 seq_puts(m, delimiter);
704 }
705
706 if (!width)
707 width = 1;
708
709 if (m->count + width >= m->size)
710 goto overflow;
711
712 len = num_to_str(m->buf + m->count, m->size - m->count, num, width);
713 if (!len)
714 goto overflow;
715
716 m->count += len;
717 return;
718
719 overflow:
720 seq_set_overflow(m);
721 }
722
723 void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
724 unsigned long long num)
725 {
726 return seq_put_decimal_ull_width(m, delimiter, num, 0);
727 }
728 EXPORT_SYMBOL(seq_put_decimal_ull);
729
730 /**
731 * seq_put_hex_ll - put a number in hexadecimal notation
732 * @m: seq_file identifying the buffer to which data should be written
733 * @delimiter: a string which is printed before the number
734 * @v: the number
735 * @width: a minimum field width
736 *
737 * seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "%08llx", v)
738 *
739 * This routine is very quick when you show lots of numbers.
740 * In usual cases, it will be better to use seq_printf(). It's easier to read.
741 */
742 void seq_put_hex_ll(struct seq_file *m, const char *delimiter,
743 unsigned long long v, unsigned int width)
744 {
745 unsigned int len;
746 int i;
747
748 if (delimiter && delimiter[0]) {
749 if (delimiter[1] == 0)
750 seq_putc(m, delimiter[0]);
751 else
752 seq_puts(m, delimiter);
753 }
754
755 /* If x is 0, the result of __builtin_clzll is undefined */
756 if (v == 0)
757 len = 1;
758 else
759 len = (sizeof(v) * 8 - __builtin_clzll(v) + 3) / 4;
760
761 if (len < width)
762 len = width;
763
764 if (m->count + len > m->size) {
765 seq_set_overflow(m);
766 return;
767 }
768
769 for (i = len - 1; i >= 0; i--) {
770 m->buf[m->count + i] = hex_asc[0xf & v];
771 v = v >> 4;
772 }
773 m->count += len;
774 }
775
776 void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num)
777 {
778 int len;
779
780 if (m->count + 3 >= m->size) /* we'll write 2 bytes at least */
781 goto overflow;
782
783 if (delimiter && delimiter[0]) {
784 if (delimiter[1] == 0)
785 seq_putc(m, delimiter[0]);
786 else
787 seq_puts(m, delimiter);
788 }
789
790 if (m->count + 2 >= m->size)
791 goto overflow;
792
793 if (num < 0) {
794 m->buf[m->count++] = '-';
795 num = -num;
796 }
797
798 if (num < 10) {
799 m->buf[m->count++] = num + '';
800 return;
801 }
802
803 len = num_to_str(m->buf + m->count, m->size - m->count, num, 0);
804 if (!len)
805 goto overflow;
806
807 m->count += len;
808 return;
809
810 overflow:
811 seq_set_overflow(m);
812 }
813 EXPORT_SYMBOL(seq_put_decimal_ll);
814
815 /**
816 * seq_write - write arbitrary data to buffer
817 * @seq: seq_file identifying the buffer to which data should be written
818 * @data: data address
819 * @len: number of bytes
820 *
821 * Return 0 on success, non-zero otherwise.
822 */
823 int seq_write(struct seq_file *seq, const void *data, size_t len)
824 {
825 if (seq->count + len < seq->size) {
826 memcpy(seq->buf + seq->count, data, len);
827 seq->count += len;
828 return 0;
829 }
830 seq_set_overflow(seq);
831 return -1;
832 }
833 EXPORT_SYMBOL(seq_write);
834
835 /**
836 * seq_pad - write padding spaces to buffer
837 * @m: seq_file identifying the buffer to which data should be written
838 * @c: the byte to append after padding if non-zero
839 */
840 void seq_pad(struct seq_file *m, char c)
841 {
842 int size = m->pad_until - m->count;
843 if (size > 0) {
844 if (size + m->count > m->size) {
845 seq_set_overflow(m);
846 return;
847 }
848 memset(m->buf + m->count, ' ', size);
849 m->count += size;
850 }
851 if (c)
852 seq_putc(m, c);
853 }
854 EXPORT_SYMBOL(seq_pad);
855
856 /* A complete analogue of print_hex_dump() */
857 void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,
858 int rowsize, int groupsize, const void *buf, size_t len,
859 bool ascii)
860 {
861 const u8 *ptr = buf;
862 int i, linelen, remaining = len;
863 char *buffer;
864 size_t size;
865 int ret;
866
867 if (rowsize != 16 && rowsize != 32)
868 rowsize = 16;
869
870 for (i = 0; i < len && !seq_has_overflowed(m); i += rowsize) {
871 linelen = min(remaining, rowsize);
872 remaining -= rowsize;
873
874 switch (prefix_type) {
875 case DUMP_PREFIX_ADDRESS:
876 seq_printf(m, "%s%p: ", prefix_str, ptr + i);
877 break;
878 case DUMP_PREFIX_OFFSET:
879 seq_printf(m, "%s%.8x: ", prefix_str, i);
880 break;
881 default:
882 seq_printf(m, "%s", prefix_str);
883 break;
884 }
885
886 size = seq_get_buf(m, &buffer);
887 ret = hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
888 buffer, size, ascii);
889 seq_commit(m, ret < size ? ret : -1);
890
891 seq_putc(m, '\n');
892 }
893 }
894 EXPORT_SYMBOL(seq_hex_dump);
895
896 struct list_head *seq_list_start(struct list_head *head, loff_t pos)
897 {
898 struct list_head *lh;
899
900 list_for_each(lh, head)
901 if (pos-- == 0)
902 return lh;
903
904 return NULL;
905 }
906 EXPORT_SYMBOL(seq_list_start);
907
908 struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
909 {
910 if (!pos)
911 return head;
912
913 return seq_list_start(head, pos - 1);
914 }
915 EXPORT_SYMBOL(seq_list_start_head);
916
917 struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
918 {
919 struct list_head *lh;
920
921 lh = ((struct list_head *)v)->next;
922 ++*ppos;
923 return lh == head ? NULL : lh;
924 }
925 EXPORT_SYMBOL(seq_list_next);
926
927 struct list_head *seq_list_start_rcu(struct list_head *head, loff_t pos)
928 {
929 struct list_head *lh;
930
931 list_for_each_rcu(lh, head)
932 if (pos-- == 0)
933 return lh;
934
935 return NULL;
936 }
937 EXPORT_SYMBOL(seq_list_start_rcu);
938
939 struct list_head *seq_list_start_head_rcu(struct list_head *head, loff_t pos)
940 {
941 if (!pos)
942 return head;
943
944 return seq_list_start_rcu(head, pos - 1);
945 }
946 EXPORT_SYMBOL(seq_list_start_head_rcu);
947
948 struct list_head *seq_list_next_rcu(void *v, struct list_head *head,
949 loff_t *ppos)
950 {
951 struct list_head *lh;
952
953 lh = list_next_rcu((struct list_head *)v);
954 ++*ppos;
955 return lh == head ? NULL : lh;
956 }
957 EXPORT_SYMBOL(seq_list_next_rcu);
958
959 /**
960 * seq_hlist_start - start an iteration of a hlist
961 * @head: the head of the hlist
962 * @pos: the start position of the sequence
963 *
964 * Called at seq_file->op->start().
965 */
966 struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
967 {
968 struct hlist_node *node;
969
970 hlist_for_each(node, head)
971 if (pos-- == 0)
972 return node;
973 return NULL;
974 }
975 EXPORT_SYMBOL(seq_hlist_start);
976
977 /**
978 * seq_hlist_start_head - start an iteration of a hlist
979 * @head: the head of the hlist
980 * @pos: the start position of the sequence
981 *
982 * Called at seq_file->op->start(). Call this function if you want to
983 * print a header at the top of the output.
984 */
985 struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
986 {
987 if (!pos)
988 return SEQ_START_TOKEN;
989
990 return seq_hlist_start(head, pos - 1);
991 }
992 EXPORT_SYMBOL(seq_hlist_start_head);
993
994 /**
995 * seq_hlist_next - move to the next position of the hlist
996 * @v: the current iterator
997 * @head: the head of the hlist
998 * @ppos: the current position
999 *
1000 * Called at seq_file->op->next().
1001 */
1002 struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
1003 loff_t *ppos)
1004 {
1005 struct hlist_node *node = v;
1006
1007 ++*ppos;
1008 if (v == SEQ_START_TOKEN)
1009 return head->first;
1010 else
1011 return node->next;
1012 }
1013 EXPORT_SYMBOL(seq_hlist_next);
1014
1015 /**
1016 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
1017 * @head: the head of the hlist
1018 * @pos: the start position of the sequence
1019 *
1020 * Called at seq_file->op->start().
1021 *
1022 * This list-traversal primitive may safely run concurrently with
1023 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1024 * as long as the traversal is guarded by rcu_read_lock().
1025 */
1026 struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
1027 loff_t pos)
1028 {
1029 struct hlist_node *node;
1030
1031 __hlist_for_each_rcu(node, head)
1032 if (pos-- == 0)
1033 return node;
1034 return NULL;
1035 }
1036 EXPORT_SYMBOL(seq_hlist_start_rcu);
1037
1038 /**
1039 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
1040 * @head: the head of the hlist
1041 * @pos: the start position of the sequence
1042 *
1043 * Called at seq_file->op->start(). Call this function if you want to
1044 * print a header at the top of the output.
1045 *
1046 * This list-traversal primitive may safely run concurrently with
1047 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1048 * as long as the traversal is guarded by rcu_read_lock().
1049 */
1050 struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
1051 loff_t pos)
1052 {
1053 if (!pos)
1054 return SEQ_START_TOKEN;
1055
1056 return seq_hlist_start_rcu(head, pos - 1);
1057 }
1058 EXPORT_SYMBOL(seq_hlist_start_head_rcu);
1059
1060 /**
1061 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
1062 * @v: the current iterator
1063 * @head: the head of the hlist
1064 * @ppos: the current position
1065 *
1066 * Called at seq_file->op->next().
1067 *
1068 * This list-traversal primitive may safely run concurrently with
1069 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1070 * as long as the traversal is guarded by rcu_read_lock().
1071 */
1072 struct hlist_node *seq_hlist_next_rcu(void *v,
1073 struct hlist_head *head,
1074 loff_t *ppos)
1075 {
1076 struct hlist_node *node = v;
1077
1078 ++*ppos;
1079 if (v == SEQ_START_TOKEN)
1080 return rcu_dereference(head->first);
1081 else
1082 return rcu_dereference(node->next);
1083 }
1084 EXPORT_SYMBOL(seq_hlist_next_rcu);
1085
1086 /**
1087 * seq_hlist_start_percpu - start an iteration of a percpu hlist array
1088 * @head: pointer to percpu array of struct hlist_heads
1089 * @cpu: pointer to cpu "cursor"
1090 * @pos: start position of sequence
1091 *
1092 * Called at seq_file->op->start().
1093 */
1094 struct hlist_node *
1095 seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
1096 {
1097 struct hlist_node *node;
1098
1099 for_each_possible_cpu(*cpu) {
1100 hlist_for_each(node, per_cpu_ptr(head, *cpu)) {
1101 if (pos-- == 0)
1102 return node;
1103 }
1104 }
1105 return NULL;
1106 }
1107 EXPORT_SYMBOL(seq_hlist_start_percpu);
1108
1109 /**
1110 * seq_hlist_next_percpu - move to the next position of the percpu hlist array
1111 * @v: pointer to current hlist_node
1112 * @head: pointer to percpu array of struct hlist_heads
1113 * @cpu: pointer to cpu "cursor"
1114 * @pos: start position of sequence
1115 *
1116 * Called at seq_file->op->next().
1117 */
1118 struct hlist_node *
1119 seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head,
1120 int *cpu, loff_t *pos)
1121 {
1122 struct hlist_node *node = v;
1123
1124 ++*pos;
1125
1126 if (node->next)
1127 return node->next;
1128
1129 for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids;
1130 *cpu = cpumask_next(*cpu, cpu_possible_mask)) {
1131 struct hlist_head *bucket = per_cpu_ptr(head, *cpu);
1132
1133 if (!hlist_empty(bucket))
1134 return bucket->first;
1135 }
1136 return NULL;
1137 }
1138 EXPORT_SYMBOL(seq_hlist_next_percpu);
1139
1140 void __init seq_file_init(void)
1141 {
1142 seq_file_cache = KMEM_CACHE(seq_file, SLAB_ACCOUNT|SLAB_PANIC);
1143 }
1144
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