blob: bbb19be260ced1be701c3651f8e5b6a94a0bb593 [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.
28 */
Helge Deller15ad7cd2006-12-06 20:40:36 -080029int seq_open(struct file *file, const struct seq_operations *op)
Linus Torvalds1da177e2005-04-16 15:20:36 -070030{
Al Viro1abe77b2005-11-07 17:15:34 -050031 struct seq_file *p = file->private_data;
32
33 if (!p) {
34 p = kmalloc(sizeof(*p), GFP_KERNEL);
35 if (!p)
36 return -ENOMEM;
37 file->private_data = p;
38 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 memset(p, 0, sizeof(*p));
Ingo Molnar0ac17592006-03-23 03:00:37 -080040 mutex_init(&p->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 p->op = op;
Linus Torvalds1da177e2005-04-16 15:20:36 -070042
43 /*
44 * Wrappers around seq_open(e.g. swaps_open) need to be
45 * aware of this. If they set f_version themselves, they
46 * should call seq_open first and then set f_version.
47 */
48 file->f_version = 0;
49
50 /* SEQ files support lseek, but not pread/pwrite */
51 file->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
52 return 0;
53}
54EXPORT_SYMBOL(seq_open);
55
56/**
57 * seq_read - ->read() method for sequential files.
Martin Waitz67be2dd2005-05-01 08:59:26 -070058 * @file: the file to read from
59 * @buf: the buffer to read to
60 * @size: the maximum number of bytes to read
61 * @ppos: the current position in the file
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 *
63 * Ready-made ->f_op->read()
64 */
65ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
66{
67 struct seq_file *m = (struct seq_file *)file->private_data;
68 size_t copied = 0;
69 loff_t pos;
70 size_t n;
71 void *p;
72 int err = 0;
73
Ingo Molnar0ac17592006-03-23 03:00:37 -080074 mutex_lock(&m->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 /*
76 * seq_file->op->..m_start/m_stop/m_next may do special actions
77 * or optimisations based on the file->f_version, so we want to
78 * pass the file->f_version to those methods.
79 *
80 * seq_file->version is just copy of f_version, and seq_file
81 * methods can treat it simply as file version.
82 * It is copied in first and copied out after all operations.
83 * It is convenient to have it as part of structure to avoid the
84 * need of passing another argument to all the seq_file methods.
85 */
86 m->version = file->f_version;
87 /* grab buffer if we didn't have one */
88 if (!m->buf) {
89 m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
90 if (!m->buf)
91 goto Enomem;
92 }
93 /* if not empty - flush it first */
94 if (m->count) {
95 n = min(m->count, size);
96 err = copy_to_user(buf, m->buf + m->from, n);
97 if (err)
98 goto Efault;
99 m->count -= n;
100 m->from += n;
101 size -= n;
102 buf += n;
103 copied += n;
104 if (!m->count)
105 m->index++;
106 if (!size)
107 goto Done;
108 }
109 /* we need at least one record in buffer */
110 while (1) {
111 pos = m->index;
112 p = m->op->start(m, &pos);
113 err = PTR_ERR(p);
114 if (!p || IS_ERR(p))
115 break;
116 err = m->op->show(m, p);
117 if (err)
118 break;
119 if (m->count < m->size)
120 goto Fill;
121 m->op->stop(m, p);
122 kfree(m->buf);
123 m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
124 if (!m->buf)
125 goto Enomem;
126 m->count = 0;
127 m->version = 0;
128 }
129 m->op->stop(m, p);
130 m->count = 0;
131 goto Done;
132Fill:
133 /* they want more? let's try to get some more */
134 while (m->count < size) {
135 size_t offs = m->count;
136 loff_t next = pos;
137 p = m->op->next(m, p, &next);
138 if (!p || IS_ERR(p)) {
139 err = PTR_ERR(p);
140 break;
141 }
142 err = m->op->show(m, p);
143 if (err || m->count == m->size) {
144 m->count = offs;
145 break;
146 }
147 pos = next;
148 }
149 m->op->stop(m, p);
150 n = min(m->count, size);
151 err = copy_to_user(buf, m->buf, n);
152 if (err)
153 goto Efault;
154 copied += n;
155 m->count -= n;
156 if (m->count)
157 m->from = n;
158 else
159 pos++;
160 m->index = pos;
161Done:
162 if (!copied)
163 copied = err;
164 else
165 *ppos += copied;
166 file->f_version = m->version;
Ingo Molnar0ac17592006-03-23 03:00:37 -0800167 mutex_unlock(&m->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 return copied;
169Enomem:
170 err = -ENOMEM;
171 goto Done;
172Efault:
173 err = -EFAULT;
174 goto Done;
175}
176EXPORT_SYMBOL(seq_read);
177
178static int traverse(struct seq_file *m, loff_t offset)
179{
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700180 loff_t pos = 0, index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 int error = 0;
182 void *p;
183
184 m->version = 0;
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700185 index = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186 m->count = m->from = 0;
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700187 if (!offset) {
188 m->index = index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 return 0;
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700190 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 if (!m->buf) {
192 m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
193 if (!m->buf)
194 return -ENOMEM;
195 }
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700196 p = m->op->start(m, &index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 while (p) {
198 error = PTR_ERR(p);
199 if (IS_ERR(p))
200 break;
201 error = m->op->show(m, p);
202 if (error)
203 break;
204 if (m->count == m->size)
205 goto Eoverflow;
206 if (pos + m->count > offset) {
207 m->from = offset - pos;
208 m->count -= m->from;
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700209 m->index = index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 break;
211 }
212 pos += m->count;
213 m->count = 0;
214 if (pos == offset) {
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700215 index++;
216 m->index = index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 break;
218 }
Alexey Dobriyancb510b82007-07-15 23:40:39 -0700219 p = m->op->next(m, p, &index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 }
221 m->op->stop(m, p);
222 return error;
223
224Eoverflow:
225 m->op->stop(m, p);
226 kfree(m->buf);
227 m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
228 return !m->buf ? -ENOMEM : -EAGAIN;
229}
230
231/**
232 * seq_lseek - ->llseek() method for sequential files.
Martin Waitz67be2dd2005-05-01 08:59:26 -0700233 * @file: the file in question
234 * @offset: new position
235 * @origin: 0 for absolute, 1 for relative position
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236 *
237 * Ready-made ->f_op->llseek()
238 */
239loff_t seq_lseek(struct file *file, loff_t offset, int origin)
240{
241 struct seq_file *m = (struct seq_file *)file->private_data;
242 long long retval = -EINVAL;
243
Ingo Molnar0ac17592006-03-23 03:00:37 -0800244 mutex_lock(&m->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 m->version = file->f_version;
246 switch (origin) {
247 case 1:
248 offset += file->f_pos;
249 case 0:
250 if (offset < 0)
251 break;
252 retval = offset;
253 if (offset != file->f_pos) {
254 while ((retval=traverse(m, offset)) == -EAGAIN)
255 ;
256 if (retval) {
257 /* with extreme prejudice... */
258 file->f_pos = 0;
259 m->version = 0;
260 m->index = 0;
261 m->count = 0;
262 } else {
263 retval = file->f_pos = offset;
264 }
265 }
266 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 file->f_version = m->version;
Alexey Dobriyan00c57462007-07-15 23:40:22 -0700268 mutex_unlock(&m->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 return retval;
270}
271EXPORT_SYMBOL(seq_lseek);
272
273/**
274 * seq_release - free the structures associated with sequential file.
275 * @file: file in question
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800276 * @inode: file->f_path.dentry->d_inode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277 *
278 * Frees the structures associated with sequential file; can be used
279 * as ->f_op->release() if you don't have private data to destroy.
280 */
281int seq_release(struct inode *inode, struct file *file)
282{
283 struct seq_file *m = (struct seq_file *)file->private_data;
284 kfree(m->buf);
285 kfree(m);
286 return 0;
287}
288EXPORT_SYMBOL(seq_release);
289
290/**
291 * seq_escape - print string into buffer, escaping some characters
292 * @m: target buffer
293 * @s: string
294 * @esc: set of characters that need escaping
295 *
296 * Puts string into buffer, replacing each occurrence of character from
297 * @esc with usual octal escape. Returns 0 in case of success, -1 - in
298 * case of overflow.
299 */
300int seq_escape(struct seq_file *m, const char *s, const char *esc)
301{
302 char *end = m->buf + m->size;
303 char *p;
304 char c;
305
306 for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) {
307 if (!strchr(esc, c)) {
308 *p++ = c;
309 continue;
310 }
311 if (p + 3 < end) {
312 *p++ = '\\';
313 *p++ = '0' + ((c & 0300) >> 6);
314 *p++ = '0' + ((c & 070) >> 3);
315 *p++ = '0' + (c & 07);
316 continue;
317 }
318 m->count = m->size;
319 return -1;
320 }
321 m->count = p - m->buf;
322 return 0;
323}
324EXPORT_SYMBOL(seq_escape);
325
326int seq_printf(struct seq_file *m, const char *f, ...)
327{
328 va_list args;
329 int len;
330
331 if (m->count < m->size) {
332 va_start(args, f);
333 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
334 va_end(args);
335 if (m->count + len < m->size) {
336 m->count += len;
337 return 0;
338 }
339 }
340 m->count = m->size;
341 return -1;
342}
343EXPORT_SYMBOL(seq_printf);
344
345int seq_path(struct seq_file *m,
346 struct vfsmount *mnt, struct dentry *dentry,
347 char *esc)
348{
349 if (m->count < m->size) {
350 char *s = m->buf + m->count;
351 char *p = d_path(dentry, mnt, s, m->size - m->count);
352 if (!IS_ERR(p)) {
353 while (s <= p) {
354 char c = *p++;
355 if (!c) {
356 p = m->buf + m->count;
357 m->count = s - m->buf;
358 return s - p;
359 } else if (!strchr(esc, c)) {
360 *s++ = c;
361 } else if (s + 4 > p) {
362 break;
363 } else {
364 *s++ = '\\';
365 *s++ = '0' + ((c & 0300) >> 6);
366 *s++ = '0' + ((c & 070) >> 3);
367 *s++ = '0' + (c & 07);
368 }
369 }
370 }
371 }
372 m->count = m->size;
373 return -1;
374}
375EXPORT_SYMBOL(seq_path);
376
377static void *single_start(struct seq_file *p, loff_t *pos)
378{
379 return NULL + (*pos == 0);
380}
381
382static void *single_next(struct seq_file *p, void *v, loff_t *pos)
383{
384 ++*pos;
385 return NULL;
386}
387
388static void single_stop(struct seq_file *p, void *v)
389{
390}
391
392int single_open(struct file *file, int (*show)(struct seq_file *, void *),
393 void *data)
394{
395 struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL);
396 int res = -ENOMEM;
397
398 if (op) {
399 op->start = single_start;
400 op->next = single_next;
401 op->stop = single_stop;
402 op->show = show;
403 res = seq_open(file, op);
404 if (!res)
405 ((struct seq_file *)file->private_data)->private = data;
406 else
407 kfree(op);
408 }
409 return res;
410}
411EXPORT_SYMBOL(single_open);
412
413int single_release(struct inode *inode, struct file *file)
414{
Helge Deller15ad7cd2006-12-06 20:40:36 -0800415 const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 int res = seq_release(inode, file);
417 kfree(op);
418 return res;
419}
420EXPORT_SYMBOL(single_release);
421
422int seq_release_private(struct inode *inode, struct file *file)
423{
424 struct seq_file *seq = file->private_data;
425
426 kfree(seq->private);
427 seq->private = NULL;
428 return seq_release(inode, file);
429}
430EXPORT_SYMBOL(seq_release_private);
431
432int seq_putc(struct seq_file *m, char c)
433{
434 if (m->count < m->size) {
435 m->buf[m->count++] = c;
436 return 0;
437 }
438 return -1;
439}
440EXPORT_SYMBOL(seq_putc);
441
442int seq_puts(struct seq_file *m, const char *s)
443{
444 int len = strlen(s);
445 if (m->count + len < m->size) {
446 memcpy(m->buf + m->count, s, len);
447 m->count += len;
448 return 0;
449 }
450 m->count = m->size;
451 return -1;
452}
453EXPORT_SYMBOL(seq_puts);
Pavel Emelianovbcf67e12007-07-10 17:22:26 -0700454
455struct list_head *seq_list_start(struct list_head *head, loff_t pos)
456{
457 struct list_head *lh;
458
459 list_for_each(lh, head)
460 if (pos-- == 0)
461 return lh;
462
463 return NULL;
464}
465
466EXPORT_SYMBOL(seq_list_start);
467
468struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
469{
470 if (!pos)
471 return head;
472
473 return seq_list_start(head, pos - 1);
474}
475
476EXPORT_SYMBOL(seq_list_start_head);
477
478struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
479{
480 struct list_head *lh;
481
482 lh = ((struct list_head *)v)->next;
483 ++*ppos;
484 return lh == head ? NULL : lh;
485}
486
487EXPORT_SYMBOL(seq_list_next);