Loading...
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}
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, READ, &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
386/**
387 * seq_escape - print string into buffer, escaping some characters
388 * @m: target buffer
389 * @s: string
390 * @esc: set of characters that need escaping
391 *
392 * Puts string into buffer, replacing each occurrence of character from
393 * @esc with usual octal escape.
394 * Use seq_has_overflowed() to check for errors.
395 */
396void seq_escape(struct seq_file *m, const char *s, const char *esc)
397{
398 seq_escape_str(m, s, ESCAPE_OCTAL, esc);
399}
400EXPORT_SYMBOL(seq_escape);
401
402void seq_vprintf(struct seq_file *m, const char *f, va_list args)
403{
404 int len;
405
406 if (m->count < m->size) {
407 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
408 if (m->count + len < m->size) {
409 m->count += len;
410 return;
411 }
412 }
413 seq_set_overflow(m);
414}
415EXPORT_SYMBOL(seq_vprintf);
416
417void seq_printf(struct seq_file *m, const char *f, ...)
418{
419 va_list args;
420
421 va_start(args, f);
422 seq_vprintf(m, f, args);
423 va_end(args);
424}
425EXPORT_SYMBOL(seq_printf);
426
427#ifdef CONFIG_BINARY_PRINTF
428void seq_bprintf(struct seq_file *m, const char *f, const u32 *binary)
429{
430 int len;
431
432 if (m->count < m->size) {
433 len = bstr_printf(m->buf + m->count, m->size - m->count, f,
434 binary);
435 if (m->count + len < m->size) {
436 m->count += len;
437 return;
438 }
439 }
440 seq_set_overflow(m);
441}
442EXPORT_SYMBOL(seq_bprintf);
443#endif /* CONFIG_BINARY_PRINTF */
444
445/**
446 * mangle_path - mangle and copy path to buffer beginning
447 * @s: buffer start
448 * @p: beginning of path in above buffer
449 * @esc: set of characters that need escaping
450 *
451 * Copy the path from @p to @s, replacing each occurrence of character from
452 * @esc with usual octal escape.
453 * Returns pointer past last written character in @s, or NULL in case of
454 * failure.
455 */
456char *mangle_path(char *s, const char *p, const char *esc)
457{
458 while (s <= p) {
459 char c = *p++;
460 if (!c) {
461 return s;
462 } else if (!strchr(esc, c)) {
463 *s++ = c;
464 } else if (s + 4 > p) {
465 break;
466 } else {
467 *s++ = '\\';
468 *s++ = '0' + ((c & 0300) >> 6);
469 *s++ = '0' + ((c & 070) >> 3);
470 *s++ = '0' + (c & 07);
471 }
472 }
473 return NULL;
474}
475EXPORT_SYMBOL(mangle_path);
476
477/**
478 * seq_path - seq_file interface to print a pathname
479 * @m: the seq_file handle
480 * @path: the struct path to print
481 * @esc: set of characters to escape in the output
482 *
483 * return the absolute path of 'path', as represented by the
484 * dentry / mnt pair in the path parameter.
485 */
486int seq_path(struct seq_file *m, const struct path *path, const char *esc)
487{
488 char *buf;
489 size_t size = seq_get_buf(m, &buf);
490 int res = -1;
491
492 if (size) {
493 char *p = d_path(path, buf, size);
494 if (!IS_ERR(p)) {
495 char *end = mangle_path(buf, p, esc);
496 if (end)
497 res = end - buf;
498 }
499 }
500 seq_commit(m, res);
501
502 return res;
503}
504EXPORT_SYMBOL(seq_path);
505
506/**
507 * seq_file_path - seq_file interface to print a pathname of a file
508 * @m: the seq_file handle
509 * @file: the struct file to print
510 * @esc: set of characters to escape in the output
511 *
512 * return the absolute path to the file.
513 */
514int seq_file_path(struct seq_file *m, struct file *file, const char *esc)
515{
516 return seq_path(m, &file->f_path, esc);
517}
518EXPORT_SYMBOL(seq_file_path);
519
520/*
521 * Same as seq_path, but relative to supplied root.
522 */
523int seq_path_root(struct seq_file *m, const struct path *path,
524 const struct path *root, const char *esc)
525{
526 char *buf;
527 size_t size = seq_get_buf(m, &buf);
528 int res = -ENAMETOOLONG;
529
530 if (size) {
531 char *p;
532
533 p = __d_path(path, root, buf, size);
534 if (!p)
535 return SEQ_SKIP;
536 res = PTR_ERR(p);
537 if (!IS_ERR(p)) {
538 char *end = mangle_path(buf, p, esc);
539 if (end)
540 res = end - buf;
541 else
542 res = -ENAMETOOLONG;
543 }
544 }
545 seq_commit(m, res);
546
547 return res < 0 && res != -ENAMETOOLONG ? res : 0;
548}
549
550/*
551 * returns the path of the 'dentry' from the root of its filesystem.
552 */
553int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
554{
555 char *buf;
556 size_t size = seq_get_buf(m, &buf);
557 int res = -1;
558
559 if (size) {
560 char *p = dentry_path(dentry, buf, size);
561 if (!IS_ERR(p)) {
562 char *end = mangle_path(buf, p, esc);
563 if (end)
564 res = end - buf;
565 }
566 }
567 seq_commit(m, res);
568
569 return res;
570}
571EXPORT_SYMBOL(seq_dentry);
572
573static void *single_start(struct seq_file *p, loff_t *pos)
574{
575 return NULL + (*pos == 0);
576}
577
578static void *single_next(struct seq_file *p, void *v, loff_t *pos)
579{
580 ++*pos;
581 return NULL;
582}
583
584static void single_stop(struct seq_file *p, void *v)
585{
586}
587
588int single_open(struct file *file, int (*show)(struct seq_file *, void *),
589 void *data)
590{
591 struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL_ACCOUNT);
592 int res = -ENOMEM;
593
594 if (op) {
595 op->start = single_start;
596 op->next = single_next;
597 op->stop = single_stop;
598 op->show = show;
599 res = seq_open(file, op);
600 if (!res)
601 ((struct seq_file *)file->private_data)->private = data;
602 else
603 kfree(op);
604 }
605 return res;
606}
607EXPORT_SYMBOL(single_open);
608
609int single_open_size(struct file *file, int (*show)(struct seq_file *, void *),
610 void *data, size_t size)
611{
612 char *buf = seq_buf_alloc(size);
613 int ret;
614 if (!buf)
615 return -ENOMEM;
616 ret = single_open(file, show, data);
617 if (ret) {
618 kvfree(buf);
619 return ret;
620 }
621 ((struct seq_file *)file->private_data)->buf = buf;
622 ((struct seq_file *)file->private_data)->size = size;
623 return 0;
624}
625EXPORT_SYMBOL(single_open_size);
626
627int single_release(struct inode *inode, struct file *file)
628{
629 const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
630 int res = seq_release(inode, file);
631 kfree(op);
632 return res;
633}
634EXPORT_SYMBOL(single_release);
635
636int seq_release_private(struct inode *inode, struct file *file)
637{
638 struct seq_file *seq = file->private_data;
639
640 kfree(seq->private);
641 seq->private = NULL;
642 return seq_release(inode, file);
643}
644EXPORT_SYMBOL(seq_release_private);
645
646void *__seq_open_private(struct file *f, const struct seq_operations *ops,
647 int psize)
648{
649 int rc;
650 void *private;
651 struct seq_file *seq;
652
653 private = kzalloc(psize, GFP_KERNEL_ACCOUNT);
654 if (private == NULL)
655 goto out;
656
657 rc = seq_open(f, ops);
658 if (rc < 0)
659 goto out_free;
660
661 seq = f->private_data;
662 seq->private = private;
663 return private;
664
665out_free:
666 kfree(private);
667out:
668 return NULL;
669}
670EXPORT_SYMBOL(__seq_open_private);
671
672int seq_open_private(struct file *filp, const struct seq_operations *ops,
673 int psize)
674{
675 return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM;
676}
677EXPORT_SYMBOL(seq_open_private);
678
679void seq_putc(struct seq_file *m, char c)
680{
681 if (m->count >= m->size)
682 return;
683
684 m->buf[m->count++] = c;
685}
686EXPORT_SYMBOL(seq_putc);
687
688void seq_puts(struct seq_file *m, const char *s)
689{
690 int len = strlen(s);
691
692 if (m->count + len >= m->size) {
693 seq_set_overflow(m);
694 return;
695 }
696 memcpy(m->buf + m->count, s, len);
697 m->count += len;
698}
699EXPORT_SYMBOL(seq_puts);
700
701/**
702 * seq_put_decimal_ull_width - A helper routine for putting decimal numbers
703 * without rich format of printf().
704 * only 'unsigned long long' is supported.
705 * @m: seq_file identifying the buffer to which data should be written
706 * @delimiter: a string which is printed before the number
707 * @num: the number
708 * @width: a minimum field width
709 *
710 * This routine will put strlen(delimiter) + number into seq_filed.
711 * This routine is very quick when you show lots of numbers.
712 * In usual cases, it will be better to use seq_printf(). It's easier to read.
713 */
714void seq_put_decimal_ull_width(struct seq_file *m, const char *delimiter,
715 unsigned long long num, unsigned int width)
716{
717 int len;
718
719 if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
720 goto overflow;
721
722 if (delimiter && delimiter[0]) {
723 if (delimiter[1] == 0)
724 seq_putc(m, delimiter[0]);
725 else
726 seq_puts(m, delimiter);
727 }
728
729 if (!width)
730 width = 1;
731
732 if (m->count + width >= m->size)
733 goto overflow;
734
735 len = num_to_str(m->buf + m->count, m->size - m->count, num, width);
736 if (!len)
737 goto overflow;
738
739 m->count += len;
740 return;
741
742overflow:
743 seq_set_overflow(m);
744}
745
746void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
747 unsigned long long num)
748{
749 return seq_put_decimal_ull_width(m, delimiter, num, 0);
750}
751EXPORT_SYMBOL(seq_put_decimal_ull);
752
753/**
754 * seq_put_hex_ll - put a number in hexadecimal notation
755 * @m: seq_file identifying the buffer to which data should be written
756 * @delimiter: a string which is printed before the number
757 * @v: the number
758 * @width: a minimum field width
759 *
760 * seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "%08llx", v)
761 *
762 * This routine is very quick when you show lots of numbers.
763 * In usual cases, it will be better to use seq_printf(). It's easier to read.
764 */
765void seq_put_hex_ll(struct seq_file *m, const char *delimiter,
766 unsigned long long v, unsigned int width)
767{
768 unsigned int len;
769 int i;
770
771 if (delimiter && delimiter[0]) {
772 if (delimiter[1] == 0)
773 seq_putc(m, delimiter[0]);
774 else
775 seq_puts(m, delimiter);
776 }
777
778 /* If x is 0, the result of __builtin_clzll is undefined */
779 if (v == 0)
780 len = 1;
781 else
782 len = (sizeof(v) * 8 - __builtin_clzll(v) + 3) / 4;
783
784 if (len < width)
785 len = width;
786
787 if (m->count + len > m->size) {
788 seq_set_overflow(m);
789 return;
790 }
791
792 for (i = len - 1; i >= 0; i--) {
793 m->buf[m->count + i] = hex_asc[0xf & v];
794 v = v >> 4;
795 }
796 m->count += len;
797}
798
799void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num)
800{
801 int len;
802
803 if (m->count + 3 >= m->size) /* we'll write 2 bytes at least */
804 goto overflow;
805
806 if (delimiter && delimiter[0]) {
807 if (delimiter[1] == 0)
808 seq_putc(m, delimiter[0]);
809 else
810 seq_puts(m, delimiter);
811 }
812
813 if (m->count + 2 >= m->size)
814 goto overflow;
815
816 if (num < 0) {
817 m->buf[m->count++] = '-';
818 num = -num;
819 }
820
821 if (num < 10) {
822 m->buf[m->count++] = num + '0';
823 return;
824 }
825
826 len = num_to_str(m->buf + m->count, m->size - m->count, num, 0);
827 if (!len)
828 goto overflow;
829
830 m->count += len;
831 return;
832
833overflow:
834 seq_set_overflow(m);
835}
836EXPORT_SYMBOL(seq_put_decimal_ll);
837
838/**
839 * seq_write - write arbitrary data to buffer
840 * @seq: seq_file identifying the buffer to which data should be written
841 * @data: data address
842 * @len: number of bytes
843 *
844 * Return 0 on success, non-zero otherwise.
845 */
846int seq_write(struct seq_file *seq, const void *data, size_t len)
847{
848 if (seq->count + len < seq->size) {
849 memcpy(seq->buf + seq->count, data, len);
850 seq->count += len;
851 return 0;
852 }
853 seq_set_overflow(seq);
854 return -1;
855}
856EXPORT_SYMBOL(seq_write);
857
858/**
859 * seq_pad - write padding spaces to buffer
860 * @m: seq_file identifying the buffer to which data should be written
861 * @c: the byte to append after padding if non-zero
862 */
863void seq_pad(struct seq_file *m, char c)
864{
865 int size = m->pad_until - m->count;
866 if (size > 0) {
867 if (size + m->count > m->size) {
868 seq_set_overflow(m);
869 return;
870 }
871 memset(m->buf + m->count, ' ', size);
872 m->count += size;
873 }
874 if (c)
875 seq_putc(m, c);
876}
877EXPORT_SYMBOL(seq_pad);
878
879/* A complete analogue of print_hex_dump() */
880void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,
881 int rowsize, int groupsize, const void *buf, size_t len,
882 bool ascii)
883{
884 const u8 *ptr = buf;
885 int i, linelen, remaining = len;
886 char *buffer;
887 size_t size;
888 int ret;
889
890 if (rowsize != 16 && rowsize != 32)
891 rowsize = 16;
892
893 for (i = 0; i < len && !seq_has_overflowed(m); i += rowsize) {
894 linelen = min(remaining, rowsize);
895 remaining -= rowsize;
896
897 switch (prefix_type) {
898 case DUMP_PREFIX_ADDRESS:
899 seq_printf(m, "%s%p: ", prefix_str, ptr + i);
900 break;
901 case DUMP_PREFIX_OFFSET:
902 seq_printf(m, "%s%.8x: ", prefix_str, i);
903 break;
904 default:
905 seq_printf(m, "%s", prefix_str);
906 break;
907 }
908
909 size = seq_get_buf(m, &buffer);
910 ret = hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
911 buffer, size, ascii);
912 seq_commit(m, ret < size ? ret : -1);
913
914 seq_putc(m, '\n');
915 }
916}
917EXPORT_SYMBOL(seq_hex_dump);
918
919struct list_head *seq_list_start(struct list_head *head, loff_t pos)
920{
921 struct list_head *lh;
922
923 list_for_each(lh, head)
924 if (pos-- == 0)
925 return lh;
926
927 return NULL;
928}
929EXPORT_SYMBOL(seq_list_start);
930
931struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
932{
933 if (!pos)
934 return head;
935
936 return seq_list_start(head, pos - 1);
937}
938EXPORT_SYMBOL(seq_list_start_head);
939
940struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
941{
942 struct list_head *lh;
943
944 lh = ((struct list_head *)v)->next;
945 ++*ppos;
946 return lh == head ? NULL : lh;
947}
948EXPORT_SYMBOL(seq_list_next);
949
950/**
951 * seq_hlist_start - start an iteration of a hlist
952 * @head: the head of the hlist
953 * @pos: the start position of the sequence
954 *
955 * Called at seq_file->op->start().
956 */
957struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
958{
959 struct hlist_node *node;
960
961 hlist_for_each(node, head)
962 if (pos-- == 0)
963 return node;
964 return NULL;
965}
966EXPORT_SYMBOL(seq_hlist_start);
967
968/**
969 * seq_hlist_start_head - start an iteration of a hlist
970 * @head: the head of the hlist
971 * @pos: the start position of the sequence
972 *
973 * Called at seq_file->op->start(). Call this function if you want to
974 * print a header at the top of the output.
975 */
976struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
977{
978 if (!pos)
979 return SEQ_START_TOKEN;
980
981 return seq_hlist_start(head, pos - 1);
982}
983EXPORT_SYMBOL(seq_hlist_start_head);
984
985/**
986 * seq_hlist_next - move to the next position of the hlist
987 * @v: the current iterator
988 * @head: the head of the hlist
989 * @ppos: the current position
990 *
991 * Called at seq_file->op->next().
992 */
993struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
994 loff_t *ppos)
995{
996 struct hlist_node *node = v;
997
998 ++*ppos;
999 if (v == SEQ_START_TOKEN)
1000 return head->first;
1001 else
1002 return node->next;
1003}
1004EXPORT_SYMBOL(seq_hlist_next);
1005
1006/**
1007 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
1008 * @head: the head of the hlist
1009 * @pos: the start position of the sequence
1010 *
1011 * Called at seq_file->op->start().
1012 *
1013 * This list-traversal primitive may safely run concurrently with
1014 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1015 * as long as the traversal is guarded by rcu_read_lock().
1016 */
1017struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
1018 loff_t pos)
1019{
1020 struct hlist_node *node;
1021
1022 __hlist_for_each_rcu(node, head)
1023 if (pos-- == 0)
1024 return node;
1025 return NULL;
1026}
1027EXPORT_SYMBOL(seq_hlist_start_rcu);
1028
1029/**
1030 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
1031 * @head: the head of the hlist
1032 * @pos: the start position of the sequence
1033 *
1034 * Called at seq_file->op->start(). Call this function if you want to
1035 * print a header at the top of the output.
1036 *
1037 * This list-traversal primitive may safely run concurrently with
1038 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1039 * as long as the traversal is guarded by rcu_read_lock().
1040 */
1041struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
1042 loff_t pos)
1043{
1044 if (!pos)
1045 return SEQ_START_TOKEN;
1046
1047 return seq_hlist_start_rcu(head, pos - 1);
1048}
1049EXPORT_SYMBOL(seq_hlist_start_head_rcu);
1050
1051/**
1052 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
1053 * @v: the current iterator
1054 * @head: the head of the hlist
1055 * @ppos: the current position
1056 *
1057 * Called at seq_file->op->next().
1058 *
1059 * This list-traversal primitive may safely run concurrently with
1060 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1061 * as long as the traversal is guarded by rcu_read_lock().
1062 */
1063struct hlist_node *seq_hlist_next_rcu(void *v,
1064 struct hlist_head *head,
1065 loff_t *ppos)
1066{
1067 struct hlist_node *node = v;
1068
1069 ++*ppos;
1070 if (v == SEQ_START_TOKEN)
1071 return rcu_dereference(head->first);
1072 else
1073 return rcu_dereference(node->next);
1074}
1075EXPORT_SYMBOL(seq_hlist_next_rcu);
1076
1077/**
1078 * seq_hlist_start_percpu - start an iteration of a percpu hlist array
1079 * @head: pointer to percpu array of struct hlist_heads
1080 * @cpu: pointer to cpu "cursor"
1081 * @pos: start position of sequence
1082 *
1083 * Called at seq_file->op->start().
1084 */
1085struct hlist_node *
1086seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
1087{
1088 struct hlist_node *node;
1089
1090 for_each_possible_cpu(*cpu) {
1091 hlist_for_each(node, per_cpu_ptr(head, *cpu)) {
1092 if (pos-- == 0)
1093 return node;
1094 }
1095 }
1096 return NULL;
1097}
1098EXPORT_SYMBOL(seq_hlist_start_percpu);
1099
1100/**
1101 * seq_hlist_next_percpu - move to the next position of the percpu hlist array
1102 * @v: pointer to current hlist_node
1103 * @head: pointer to percpu array of struct hlist_heads
1104 * @cpu: pointer to cpu "cursor"
1105 * @pos: start position of sequence
1106 *
1107 * Called at seq_file->op->next().
1108 */
1109struct hlist_node *
1110seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head,
1111 int *cpu, loff_t *pos)
1112{
1113 struct hlist_node *node = v;
1114
1115 ++*pos;
1116
1117 if (node->next)
1118 return node->next;
1119
1120 for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids;
1121 *cpu = cpumask_next(*cpu, cpu_possible_mask)) {
1122 struct hlist_head *bucket = per_cpu_ptr(head, *cpu);
1123
1124 if (!hlist_empty(bucket))
1125 return bucket->first;
1126 }
1127 return NULL;
1128}
1129EXPORT_SYMBOL(seq_hlist_next_percpu);
1130
1131void __init seq_file_init(void)
1132{
1133 seq_file_cache = KMEM_CACHE(seq_file, SLAB_ACCOUNT|SLAB_PANIC);
1134}