blob: eba2eabcd2b86a40495845053d9d647e228540f9 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/seq_file.c
3 *
4 * helper functions for making synthetic files from sequences of records.
5 * initial implementation -- AV, Oct 2001.
6 */
7
8#include <linux/fs.h>
9#include <linux/module.h>
10#include <linux/seq_file.h>
11#include <linux/slab.h>
12
13#include <asm/uaccess.h>
14#include <asm/page.h>
15
16/**
17 * seq_open - initialize sequential file
18 * @file: file we initialize
19 * @op: method table describing the sequence
20 *
21 * seq_open() sets @file, associating it with a sequence described
22 * by @op. @op->start() sets the iterator up and returns the first
23 * element of sequence. @op->stop() shuts it down. @op->next()
24 * returns the next element of sequence. @op->show() prints element
25 * into the buffer. In case of error ->start() and ->next() return
26 * ERR_PTR(error). In the end of sequence they return %NULL. ->show()
27 * returns 0 in case of success and negative number in case of error.
Al Viro521b5d02008-03-28 00:46:41 -040028 * Returning SEQ_SKIP means "discard this element and move on".
Linus Torvalds1da177e2005-04-16 15:20:36 -070029 */
Helge Deller15ad7cd2006-12-06 20:40:36 -080030int seq_open(struct file *file, const struct seq_operations *op)
Linus Torvalds1da177e2005-04-16 15:20:36 -070031{
Al Viro1abe77b2005-11-07 17:15:34 -050032 struct seq_file *p = file->private_data;
33
34 if (!p) {
35 p = kmalloc(sizeof(*p), GFP_KERNEL);
36 if (!p)
37 return -ENOMEM;
38 file->private_data = p;
39 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 memset(p, 0, sizeof(*p));
Ingo Molnar0ac17592006-03-23 03:00:37 -080041 mutex_init(&p->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070042 p->op = op;
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
44 /*
45 * Wrappers around seq_open(e.g. swaps_open) need to be
46 * aware of this. If they set f_version themselves, they
47 * should call seq_open first and then set f_version.
48 */
49 file->f_version = 0;
50
51 /* SEQ files support lseek, but not pread/pwrite */
52 file->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
53 return 0;
54}
55EXPORT_SYMBOL(seq_open);
56
57/**
58 * seq_read - ->read() method for sequential files.
Martin Waitz67be2dd2005-05-01 08:59:26 -070059 * @file: the file to read from
60 * @buf: the buffer to read to
61 * @size: the maximum number of bytes to read
62 * @ppos: the current position in the file
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 *
64 * Ready-made ->f_op->read()
65 */
66ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
67{
68 struct seq_file *m = (struct seq_file *)file->private_data;
69 size_t copied = 0;
70 loff_t pos;
71 size_t n;
72 void *p;
73 int err = 0;
74
Ingo Molnar0ac17592006-03-23 03:00:37 -080075 mutex_lock(&m->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 /*
77 * seq_file->op->..m_start/m_stop/m_next may do special actions
78 * or optimisations based on the file->f_version, so we want to
79 * pass the file->f_version to those methods.
80 *
81 * seq_file->version is just copy of f_version, and seq_file
82 * methods can treat it simply as file version.
83 * It is copied in first and copied out after all operations.
84 * It is convenient to have it as part of structure to avoid the
85 * need of passing another argument to all the seq_file methods.
86 */
87 m->version = file->f_version;
88 /* grab buffer if we didn't have one */
89 if (!m->buf) {
90 m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
91 if (!m->buf)
92 goto Enomem;
93 }
94 /* if not empty - flush it first */
95 if (m->count) {
96 n = min(m->count, size);
97 err = copy_to_user(buf, m->buf + m->from, n);
98 if (err)
99 goto Efault;
100 m->count -= n;
101 m->from += n;
102 size -= n;
103 buf += n;
104 copied += n;
105 if (!m->count)
106 m->index++;
107 if (!size)
108 goto Done;
109 }
110 /* we need at least one record in buffer */
Al Viro4cdfe842008-08-24 07:45:33 -0400111 pos = m->index;
112 p = m->op->start(m, &pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 while (1) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 err = PTR_ERR(p);
115 if (!p || IS_ERR(p))
116 break;
117 err = m->op->show(m, p);
Al Viro521b5d02008-03-28 00:46:41 -0400118 if (err < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119 break;
Al Viro521b5d02008-03-28 00:46:41 -0400120 if (unlikely(err))
121 m->count = 0;
Al Viro4cdfe842008-08-24 07:45:33 -0400122 if (unlikely(!m->count)) {
123 p = m->op->next(m, p, &pos);
124 m->index = pos;
125 continue;
126 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 if (m->count < m->size)
128 goto Fill;
129 m->op->stop(m, p);
130 kfree(m->buf);
131 m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
132 if (!m->buf)
133 goto Enomem;
134 m->count = 0;
135 m->version = 0;
Al Viro4cdfe842008-08-24 07:45:33 -0400136 pos = m->index;
137 p = m->op->start(m, &pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 }
139 m->op->stop(m, p);
140 m->count = 0;
141 goto Done;
142Fill:
143 /* they want more? let's try to get some more */
144 while (m->count < size) {
145 size_t offs = m->count;
146 loff_t next = pos;
147 p = m->op->next(m, p, &next);
148 if (!p || IS_ERR(p)) {
149 err = PTR_ERR(p);
150 break;
151 }
152 err = m->op->show(m, p);
Al Viro521b5d02008-03-28 00:46:41 -0400153 if (m->count == m->size || err) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 m->count = offs;
Al Viro521b5d02008-03-28 00:46:41 -0400155 if (likely(err <= 0))
156 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 }
158 pos = next;
159 }
160 m->op->stop(m, p);
161 n = min(m->count, size);
162 err = copy_to_user(buf, m->buf, n);
163 if (err)
164 goto Efault;
165 copied += n;
166 m->count -= n;
167 if (m->count)
168 m->from = n;
169 else
170 pos++;
171 m->index = pos;
172Done:
173 if (!copied)
174 copied = err;
175 else
176 *ppos += copied;
177 file->f_version = m->version;
Ingo Molnar0ac17592006-03-23 03:00:37 -0800178 mutex_unlock(&m->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 return copied;
180Enomem:
181 err = -ENOMEM;
182 goto Done;
183Efault:
184 err = -EFAULT;
185 goto Done;
186}
187EXPORT_SYMBOL(seq_read);
188
189static int traverse(struct seq_file *m, loff_t offset)
190{
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700191 loff_t pos = 0, index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 int error = 0;
193 void *p;
194
195 m->version = 0;
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700196 index = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 m->count = m->from = 0;
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700198 if (!offset) {
199 m->index = index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200 return 0;
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700201 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202 if (!m->buf) {
203 m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
204 if (!m->buf)
205 return -ENOMEM;
206 }
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700207 p = m->op->start(m, &index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208 while (p) {
209 error = PTR_ERR(p);
210 if (IS_ERR(p))
211 break;
212 error = m->op->show(m, p);
Al Viro521b5d02008-03-28 00:46:41 -0400213 if (error < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 break;
Al Viro521b5d02008-03-28 00:46:41 -0400215 if (unlikely(error)) {
216 error = 0;
217 m->count = 0;
218 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 if (m->count == m->size)
220 goto Eoverflow;
221 if (pos + m->count > offset) {
222 m->from = offset - pos;
223 m->count -= m->from;
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700224 m->index = index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 break;
226 }
227 pos += m->count;
228 m->count = 0;
229 if (pos == offset) {
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700230 index++;
231 m->index = index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 break;
233 }
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700234 p = m->op->next(m, p, &index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 }
236 m->op->stop(m, p);
237 return error;
238
239Eoverflow:
240 m->op->stop(m, p);
241 kfree(m->buf);
242 m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
243 return !m->buf ? -ENOMEM : -EAGAIN;
244}
245
246/**
247 * seq_lseek - ->llseek() method for sequential files.
Martin Waitz67be2dd2005-05-01 08:59:26 -0700248 * @file: the file in question
249 * @offset: new position
250 * @origin: 0 for absolute, 1 for relative position
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 *
252 * Ready-made ->f_op->llseek()
253 */
254loff_t seq_lseek(struct file *file, loff_t offset, int origin)
255{
256 struct seq_file *m = (struct seq_file *)file->private_data;
David Sterba16abef02008-04-22 15:09:22 +0200257 loff_t retval = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258
Ingo Molnar0ac17592006-03-23 03:00:37 -0800259 mutex_lock(&m->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 m->version = file->f_version;
261 switch (origin) {
262 case 1:
263 offset += file->f_pos;
264 case 0:
265 if (offset < 0)
266 break;
267 retval = offset;
268 if (offset != file->f_pos) {
269 while ((retval=traverse(m, offset)) == -EAGAIN)
270 ;
271 if (retval) {
272 /* with extreme prejudice... */
273 file->f_pos = 0;
274 m->version = 0;
275 m->index = 0;
276 m->count = 0;
277 } else {
278 retval = file->f_pos = offset;
279 }
280 }
281 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282 file->f_version = m->version;
Alexey Dobriyan00c57462007-07-15 23:40:22 -0700283 mutex_unlock(&m->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 return retval;
285}
286EXPORT_SYMBOL(seq_lseek);
287
288/**
289 * seq_release - free the structures associated with sequential file.
290 * @file: file in question
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800291 * @inode: file->f_path.dentry->d_inode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 *
293 * Frees the structures associated with sequential file; can be used
294 * as ->f_op->release() if you don't have private data to destroy.
295 */
296int seq_release(struct inode *inode, struct file *file)
297{
298 struct seq_file *m = (struct seq_file *)file->private_data;
299 kfree(m->buf);
300 kfree(m);
301 return 0;
302}
303EXPORT_SYMBOL(seq_release);
304
305/**
306 * seq_escape - print string into buffer, escaping some characters
307 * @m: target buffer
308 * @s: string
309 * @esc: set of characters that need escaping
310 *
311 * Puts string into buffer, replacing each occurrence of character from
312 * @esc with usual octal escape. Returns 0 in case of success, -1 - in
313 * case of overflow.
314 */
315int seq_escape(struct seq_file *m, const char *s, const char *esc)
316{
317 char *end = m->buf + m->size;
318 char *p;
319 char c;
320
321 for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) {
322 if (!strchr(esc, c)) {
323 *p++ = c;
324 continue;
325 }
326 if (p + 3 < end) {
327 *p++ = '\\';
328 *p++ = '0' + ((c & 0300) >> 6);
329 *p++ = '0' + ((c & 070) >> 3);
330 *p++ = '0' + (c & 07);
331 continue;
332 }
333 m->count = m->size;
334 return -1;
335 }
336 m->count = p - m->buf;
337 return 0;
338}
339EXPORT_SYMBOL(seq_escape);
340
341int seq_printf(struct seq_file *m, const char *f, ...)
342{
343 va_list args;
344 int len;
345
346 if (m->count < m->size) {
347 va_start(args, f);
348 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
349 va_end(args);
350 if (m->count + len < m->size) {
351 m->count += len;
352 return 0;
353 }
354 }
355 m->count = m->size;
356 return -1;
357}
358EXPORT_SYMBOL(seq_printf);
359
Ram Pai6092d042008-03-27 13:06:20 +0100360static char *mangle_path(char *s, char *p, char *esc)
361{
362 while (s <= p) {
363 char c = *p++;
364 if (!c) {
365 return s;
366 } else if (!strchr(esc, c)) {
367 *s++ = c;
368 } else if (s + 4 > p) {
369 break;
370 } else {
371 *s++ = '\\';
372 *s++ = '0' + ((c & 0300) >> 6);
373 *s++ = '0' + ((c & 070) >> 3);
374 *s++ = '0' + (c & 07);
375 }
376 }
377 return NULL;
378}
379
380/*
381 * return the absolute path of 'dentry' residing in mount 'mnt'.
382 */
Jan Blunckc32c2f62008-02-14 19:38:43 -0800383int seq_path(struct seq_file *m, struct path *path, char *esc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384{
385 if (m->count < m->size) {
386 char *s = m->buf + m->count;
Jan Blunckcf28b482008-02-14 19:38:44 -0800387 char *p = d_path(path, s, m->size - m->count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 if (!IS_ERR(p)) {
Ram Pai6092d042008-03-27 13:06:20 +0100389 s = mangle_path(s, p, esc);
390 if (s) {
391 p = m->buf + m->count;
392 m->count = s - m->buf;
393 return s - p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 }
395 }
396 }
397 m->count = m->size;
398 return -1;
399}
400EXPORT_SYMBOL(seq_path);
401
Ram Pai6092d042008-03-27 13:06:20 +0100402/*
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +0100403 * Same as seq_path, but relative to supplied root.
404 *
405 * root may be changed, see __d_path().
406 */
407int seq_path_root(struct seq_file *m, struct path *path, struct path *root,
408 char *esc)
409{
410 int err = -ENAMETOOLONG;
411 if (m->count < m->size) {
412 char *s = m->buf + m->count;
413 char *p;
414
415 spin_lock(&dcache_lock);
416 p = __d_path(path, root, s, m->size - m->count);
417 spin_unlock(&dcache_lock);
418 err = PTR_ERR(p);
419 if (!IS_ERR(p)) {
420 s = mangle_path(s, p, esc);
421 if (s) {
422 p = m->buf + m->count;
423 m->count = s - m->buf;
424 return 0;
425 }
426 }
427 }
428 m->count = m->size;
429 return err;
430}
431
432/*
Ram Pai6092d042008-03-27 13:06:20 +0100433 * returns the path of the 'dentry' from the root of its filesystem.
434 */
435int seq_dentry(struct seq_file *m, struct dentry *dentry, char *esc)
436{
437 if (m->count < m->size) {
438 char *s = m->buf + m->count;
439 char *p = dentry_path(dentry, s, m->size - m->count);
440 if (!IS_ERR(p)) {
441 s = mangle_path(s, p, esc);
442 if (s) {
443 p = m->buf + m->count;
444 m->count = s - m->buf;
445 return s - p;
446 }
447 }
448 }
449 m->count = m->size;
450 return -1;
451}
452
Alexey Dobriyan50ac2d62008-08-12 15:09:02 -0700453int seq_bitmap(struct seq_file *m, unsigned long *bits, unsigned int nr_bits)
454{
Lai Jiangshan85dd0302008-10-18 20:28:18 -0700455 if (m->count < m->size) {
456 int len = bitmap_scnprintf(m->buf + m->count,
457 m->size - m->count, bits, nr_bits);
458 if (m->count + len < m->size) {
459 m->count += len;
460 return 0;
461 }
Alexey Dobriyan50ac2d62008-08-12 15:09:02 -0700462 }
463 m->count = m->size;
464 return -1;
465}
Lai Jiangshan85dd0302008-10-18 20:28:18 -0700466EXPORT_SYMBOL(seq_bitmap);
Alexey Dobriyan50ac2d62008-08-12 15:09:02 -0700467
Lai Jiangshan3eda2012008-10-18 20:28:19 -0700468int seq_bitmap_list(struct seq_file *m, unsigned long *bits,
469 unsigned int nr_bits)
470{
471 if (m->count < m->size) {
472 int len = bitmap_scnlistprintf(m->buf + m->count,
473 m->size - m->count, bits, nr_bits);
474 if (m->count + len < m->size) {
475 m->count += len;
476 return 0;
477 }
478 }
479 m->count = m->size;
480 return -1;
481}
482EXPORT_SYMBOL(seq_bitmap_list);
483
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484static void *single_start(struct seq_file *p, loff_t *pos)
485{
486 return NULL + (*pos == 0);
487}
488
489static void *single_next(struct seq_file *p, void *v, loff_t *pos)
490{
491 ++*pos;
492 return NULL;
493}
494
495static void single_stop(struct seq_file *p, void *v)
496{
497}
498
499int single_open(struct file *file, int (*show)(struct seq_file *, void *),
500 void *data)
501{
502 struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL);
503 int res = -ENOMEM;
504
505 if (op) {
506 op->start = single_start;
507 op->next = single_next;
508 op->stop = single_stop;
509 op->show = show;
510 res = seq_open(file, op);
511 if (!res)
512 ((struct seq_file *)file->private_data)->private = data;
513 else
514 kfree(op);
515 }
516 return res;
517}
518EXPORT_SYMBOL(single_open);
519
520int single_release(struct inode *inode, struct file *file)
521{
Helge Deller15ad7cd2006-12-06 20:40:36 -0800522 const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523 int res = seq_release(inode, file);
524 kfree(op);
525 return res;
526}
527EXPORT_SYMBOL(single_release);
528
529int seq_release_private(struct inode *inode, struct file *file)
530{
531 struct seq_file *seq = file->private_data;
532
533 kfree(seq->private);
534 seq->private = NULL;
535 return seq_release(inode, file);
536}
537EXPORT_SYMBOL(seq_release_private);
538
Pavel Emelyanov39699032007-10-10 02:28:42 -0700539void *__seq_open_private(struct file *f, const struct seq_operations *ops,
540 int psize)
541{
542 int rc;
543 void *private;
544 struct seq_file *seq;
545
546 private = kzalloc(psize, GFP_KERNEL);
547 if (private == NULL)
548 goto out;
549
550 rc = seq_open(f, ops);
551 if (rc < 0)
552 goto out_free;
553
554 seq = f->private_data;
555 seq->private = private;
556 return private;
557
558out_free:
559 kfree(private);
560out:
561 return NULL;
562}
563EXPORT_SYMBOL(__seq_open_private);
564
565int seq_open_private(struct file *filp, const struct seq_operations *ops,
566 int psize)
567{
568 return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM;
569}
570EXPORT_SYMBOL(seq_open_private);
571
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572int seq_putc(struct seq_file *m, char c)
573{
574 if (m->count < m->size) {
575 m->buf[m->count++] = c;
576 return 0;
577 }
578 return -1;
579}
580EXPORT_SYMBOL(seq_putc);
581
582int seq_puts(struct seq_file *m, const char *s)
583{
584 int len = strlen(s);
585 if (m->count + len < m->size) {
586 memcpy(m->buf + m->count, s, len);
587 m->count += len;
588 return 0;
589 }
590 m->count = m->size;
591 return -1;
592}
593EXPORT_SYMBOL(seq_puts);
Pavel Emelianovbcf67e12007-07-10 17:22:26 -0700594
595struct list_head *seq_list_start(struct list_head *head, loff_t pos)
596{
597 struct list_head *lh;
598
599 list_for_each(lh, head)
600 if (pos-- == 0)
601 return lh;
602
603 return NULL;
604}
605
606EXPORT_SYMBOL(seq_list_start);
607
608struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
609{
610 if (!pos)
611 return head;
612
613 return seq_list_start(head, pos - 1);
614}
615
616EXPORT_SYMBOL(seq_list_start_head);
617
618struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
619{
620 struct list_head *lh;
621
622 lh = ((struct list_head *)v)->next;
623 ++*ppos;
624 return lh == head ? NULL : lh;
625}
626
627EXPORT_SYMBOL(seq_list_next);