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 	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  */
seq_open(struct file * file,const struct seq_operations * op)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 
traverse(struct seq_file * m,loff_t offset)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  */
seq_read(struct file * file,char __user * buf,size_t size,loff_t * ppos)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  */
seq_read_iter(struct kiocb * iocb,struct iov_iter * iter)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  */
seq_lseek(struct file * file,loff_t offset,int whence)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  */
seq_release(struct inode * inode,struct file * file)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  */
seq_escape_mem(struct seq_file * m,const char * src,size_t len,unsigned int flags,const char * esc)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 
seq_vprintf(struct seq_file * m,const char * f,va_list args)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 
seq_printf(struct seq_file * m,const char * f,...)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
seq_bprintf(struct seq_file * m,const char * f,const u32 * binary)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  */
mangle_path(char * s,const char * p,const char * esc)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++ = '0' + ((c & 0300) >> 6);
453 			*s++ = '0' + ((c & 070) >> 3);
454 			*s++ = '0' + (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  */
seq_path(struct seq_file * m,const struct path * path,const char * esc)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  */
seq_file_path(struct seq_file * m,struct file * file,const char * esc)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  */
seq_path_root(struct seq_file * m,const struct path * path,const struct path * root,const char * esc)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  */
seq_dentry(struct seq_file * m,struct dentry * dentry,const char * esc)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 
single_start(struct seq_file * p,loff_t * pos)557 void *single_start(struct seq_file *p, loff_t *pos)
558 {
559 	return *pos ? NULL : SEQ_START_TOKEN;
560 }
561 
single_next(struct seq_file * p,void * v,loff_t * pos)562 static void *single_next(struct seq_file *p, void *v, loff_t *pos)
563 {
564 	++*pos;
565 	return NULL;
566 }
567 
single_stop(struct seq_file * p,void * v)568 static void single_stop(struct seq_file *p, void *v)
569 {
570 }
571 
single_open(struct file * file,int (* show)(struct seq_file *,void *),void * data)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 
single_open_size(struct file * file,int (* show)(struct seq_file *,void *),void * data,size_t size)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 
single_release(struct inode * inode,struct file * file)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 
seq_release_private(struct inode * inode,struct file * file)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 
__seq_open_private(struct file * f,const struct seq_operations * ops,int psize)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 
seq_open_private(struct file * filp,const struct seq_operations * ops,int psize)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 
seq_putc(struct seq_file * m,char c)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 
seq_puts(struct seq_file * m,const char * s)672 void 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 }
683 EXPORT_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  */
seq_put_decimal_ull_width(struct seq_file * m,const char * delimiter,unsigned long long num,unsigned int width)698 void 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 
726 overflow:
727 	seq_set_overflow(m);
728 }
729 
seq_put_decimal_ull(struct seq_file * m,const char * delimiter,unsigned long long num)730 void 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 }
735 EXPORT_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  */
seq_put_hex_ll(struct seq_file * m,const char * delimiter,unsigned long long v,unsigned int width)749 void 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 
seq_put_decimal_ll(struct seq_file * m,const char * delimiter,long long num)783 void 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 
817 overflow:
818 	seq_set_overflow(m);
819 }
820 EXPORT_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  */
seq_write(struct seq_file * seq,const void * data,size_t len)830 int 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 }
840 EXPORT_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  */
seq_pad(struct seq_file * m,char c)847 void 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 }
861 EXPORT_SYMBOL(seq_pad);
862 
863 /* 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)864 void 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 }
901 EXPORT_SYMBOL(seq_hex_dump);
902 
seq_list_start(struct list_head * head,loff_t pos)903 struct 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 }
913 EXPORT_SYMBOL(seq_list_start);
914 
seq_list_start_head(struct list_head * head,loff_t pos)915 struct 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 }
922 EXPORT_SYMBOL(seq_list_start_head);
923 
seq_list_next(void * v,struct list_head * head,loff_t * ppos)924 struct 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 }
932 EXPORT_SYMBOL(seq_list_next);
933 
seq_list_start_rcu(struct list_head * head,loff_t pos)934 struct 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 }
944 EXPORT_SYMBOL(seq_list_start_rcu);
945 
seq_list_start_head_rcu(struct list_head * head,loff_t pos)946 struct 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 }
953 EXPORT_SYMBOL(seq_list_start_head_rcu);
954 
seq_list_next_rcu(void * v,struct list_head * head,loff_t * ppos)955 struct 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 }
964 EXPORT_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  */
seq_hlist_start(struct hlist_head * head,loff_t pos)973 struct 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 }
982 EXPORT_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  */
seq_hlist_start_head(struct hlist_head * head,loff_t pos)992 struct 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 }
999 EXPORT_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  */
seq_hlist_next(void * v,struct hlist_head * head,loff_t * ppos)1009 struct 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 }
1020 EXPORT_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  */
seq_hlist_start_rcu(struct hlist_head * head,loff_t pos)1033 struct 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 }
1043 EXPORT_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  */
seq_hlist_start_head_rcu(struct hlist_head * head,loff_t pos)1057 struct 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 }
1065 EXPORT_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  */
seq_hlist_next_rcu(void * v,struct hlist_head * head,loff_t * ppos)1079 struct 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 }
1091 EXPORT_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  */
1101 struct hlist_node *
seq_hlist_start_percpu(struct hlist_head __percpu * head,int * cpu,loff_t pos)1102 seq_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 }
1114 EXPORT_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  */
1125 struct hlist_node *
seq_hlist_next_percpu(void * v,struct hlist_head __percpu * head,int * cpu,loff_t * pos)1126 seq_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 }
1145 EXPORT_SYMBOL(seq_hlist_next_percpu);
1146 
seq_file_init(void)1147 void __init seq_file_init(void)
1148 {
1149 	seq_file_cache = KMEM_CACHE(seq_file, SLAB_ACCOUNT|SLAB_PANIC);
1150 }
1151