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