aboutsummaryrefslogtreecommitdiffstats
path: root/fs/seq_file.c
blob: cdfd996ca6ef3062772ab39cf4067bbebc0eb230 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
/*
 * linux/fs/seq_file.c
 *
 * helper functions for making synthetic files from sequences of records.
 * initial implementation -- AV, Oct 2001.
 */

#include <linux/fs.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/slab.h>

#include <asm/uaccess.h>
#include <asm/page.h>

/**
 *	seq_open -	initialize sequential file
 *	@file: file we initialize
 *	@op: method table describing the sequence
 *
 *	seq_open() sets @file, associating it with a sequence described
 *	by @op.  @op->start() sets the iterator up and returns the first
 *	element of sequence. @op->stop() shuts it down.  @op->next()
 *	returns the next element of sequence.  @op->show() prints element
 *	into the buffer.  In case of error ->start() and ->next() return
 *	ERR_PTR(error).  In the end of sequence they return %NULL. ->show()
 *	returns 0 in case of success and negative number in case of error.
 *	Returning SEQ_SKIP means "discard this element and move on".
 */
int seq_open(struct file *file, const struct seq_operations *op)
{
	struct seq_file *p = file->private_data;

	if (!p) {
		p = kmalloc(sizeof(*p), GFP_KERNEL);
		if (!p)
			return -ENOMEM;
		file->private_data = p;
	}
	memset(p, 0, sizeof(*p));
	mutex_init(&p->lock);
	p->op = op;

	/*
	 * Wrappers around seq_open(e.g. swaps_open) need to be
	 * aware of this. If they set f_version themselves, they
	 * should call seq_open first and then set f_version.
	 */
	file->f_version = 0;

	/* SEQ files support lseek, but not pread/pwrite */
	file->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
	return 0;
}
EXPORT_SYMBOL(seq_open);

/**
 *	seq_read -	->read() method for sequential files.
 *	@file: the file to read from
 *	@buf: the buffer to read to
 *	@size: the maximum number of bytes to read
 *	@ppos: the current position in the file
 *
 *	Ready-made ->f_op->read()
 */
ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
	struct seq_file *m = (struct seq_file *)file->private_data;
	size_t copied = 0;
	loff_t pos;
	size_t n;
	void *p;
	int err = 0;

	mutex_lock(&m->lock);
	/*
	 * seq_file->op->..m_start/m_stop/m_next may do special actions
	 * or optimisations based on the file->f_version, so we want to
	 * pass the file->f_version to those methods.
	 *
	 * seq_file->version is just copy of f_version, and seq_file
	 * methods can treat it simply as file version.
	 * It is copied in first and copied out after all operations.
	 * It is convenient to have it as  part of structure to avoid the
	 * need of passing another argument to all the seq_file methods.
	 */
	m->version = file->f_version;
	/* grab buffer if we didn't have one */
	if (!m->buf) {
		m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
		if (!m->buf)
			goto Enomem;
	}
	/* if not empty - flush it first */
	if (m->count) {
		n = min(m->count, size);
		err = copy_to_user(buf, m->buf + m->from, n);
		if (err)
			goto Efault;
		m->count -= n;
		m->from += n;
		size -= n;
		buf += n;
		copied += n;
		if (!m->count)
			m->index++;
		if (!size)
			goto Done;
	}
	/* we need at least one record in buffer */
	while (1) {
		pos = m->index;
		p = m->op->start(m, &pos);
		err = PTR_ERR(p);
		if (!p || IS_ERR(p))
			break;
		err = m->op->show(m, p);
		if (err < 0)
			break;
		if (unlikely(err))
			m->count = 0;
		if (m->count < m->size)
			goto Fill;
		m->op->stop(m, p);
		kfree(m->buf);
		m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
		if (!m->buf)
			goto Enomem;
		m->count = 0;
		m->version = 0;
	}
	m->op->stop(m, p);
	m->count = 0;
	goto Done;
Fill:
	/* they want more? let's try to get some more */
	while (m->count < size) {
		size_t offs = m->count;
		loff_t next = pos;
		p = m->op->next(m, p, &next);
		if (!p || IS_ERR(p)) {
			err = PTR_ERR(p);
			break;
		}
		err = m->op->show(m, p);
		if (m->count == m->size || err) {
			m->count = offs;
			if (likely(err <= 0))
				break;
		}
		pos = next;
	}
	m->op->stop(m, p);
	n = min(m->count, size);
	err = copy_to_user(buf, m->buf, n);
	if (err)
		goto Efault;
	copied += n;
	m->count -= n;
	if (m->count)
		m->from = n;
	else
		pos++;
	m->index = pos;
Done:
	if (!copied)
		copied = err;
	else
		*ppos += copied;
	file->f_version = m->version;
	mutex_unlock(&m->lock);
	return copied;
Enomem:
	err = -ENOMEM;
	goto Done;
Efault:
	err = -EFAULT;
	goto Done;
}
EXPORT_SYMBOL(seq_read);

static int traverse(struct seq_file *m, loff_t offset)
{
	loff_t pos = 0, index;
	int error = 0;
	void *p;

	m->version = 0;
	index = 0;
	m->count = m->from = 0;
	if (!offset) {
		m->index = index;
		return 0;
	}
	if (!m->buf) {
		m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
		if (!m->buf)
			return -ENOMEM;
	}
	p = m->op->start(m, &index);
	while (p) {
		error = PTR_ERR(p);
		if (IS_ERR(p))
			break;
		error = m->op->show(m, p);
		if (error < 0)
			break;
		if (unlikely(error)) {
			error = 0;
			m->count = 0;
		}
		if (m->count == m->size)
			goto Eoverflow;
		if (pos + m->count > offset) {
			m->from = offset - pos;
			m->count -= m->from;
			m->index = index;
			break;
		}
		pos += m->count;
		m->count = 0;
		if (pos == offset) {
			index++;
			m->index = index;
			break;
		}
		p = m->op->next(m, p, &index);
	}
	m->op->stop(m, p);
	return error;

Eoverflow:
	m->op->stop(m, p);
	kfree(m->buf);
	m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
	return !m->buf ? -ENOMEM : -EAGAIN;
}

/**
 *	seq_lseek -	->llseek() method for sequential files.
 *	@file: the file in question
 *	@offset: new position
 *	@origin: 0 for absolute, 1 for relative position
 *
 *	Ready-made ->f_op->llseek()
 */
loff_t seq_lseek(struct file *file, loff_t offset, int origin)
{
	struct seq_file *m = (struct seq_file *)file->private_data;
	loff_t retval = -EINVAL;

	mutex_lock(&m->lock);
	m->version = file->f_version;
	switch (origin) {
		case 1:
			offset += file->f_pos;
		case 0:
			if (offset < 0)
				break;
			retval = offset;
			if (offset != file->f_pos) {
				while ((retval=traverse(m, offset)) == -EAGAIN)
					;
				if (retval) {
					/* with extreme prejudice... */
					file->f_pos = 0;
					m->version = 0;
					m->index = 0;
					m->count = 0;
				} else {
					retval = file->f_pos = offset;
				}
			}
	}
	file->f_version = m->version;
	mutex_unlock(&m->lock);
	return retval;
}
EXPORT_SYMBOL(seq_lseek);

/**
 *	seq_release -	free the structures associated with sequential file.
 *	@file: file in question
 *	@inode: file->f_path.dentry->d_inode
 *
 *	Frees the structures associated with sequential file; can be used
 *	as ->f_op->release() if you don't have private data to destroy.
 */
int seq_release(struct inode *inode, struct file *file)
{
	struct seq_file *m = (struct seq_file *)file->private_data;
	kfree(m->buf);
	kfree(m);
	return 0;
}
EXPORT_SYMBOL(seq_release);

/**
 *	seq_escape -	print string into buffer, escaping some characters
 *	@m:	target buffer
 *	@s:	string
 *	@esc:	set of characters that need escaping
 *
 *	Puts string into buffer, replacing each occurrence of character from
 *	@esc with usual octal escape.  Returns 0 in case of success, -1 - in
 *	case of overflow.
 */
int seq_escape(struct seq_file *m, const char *s, const char *esc)
{
	char *end = m->buf + m->size;
        char *p;
	char c;

        for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) {
		if (!strchr(esc, c)) {
			*p++ = c;
			continue;
		}
		if (p + 3 < end) {
			*p++ = '\\';
			*p++ = '0' + ((c & 0300) >> 6);
			*p++ = '0' + ((c & 070) >> 3);
			*p++ = '0' + (c & 07);
			continue;
		}
		m->count = m->size;
		return -1;
        }
	m->count = p - m->buf;
        return 0;
}
EXPORT_SYMBOL(seq_escape);

int seq_printf(struct seq_file *m, const char *f, ...)
{
	va_list args;
	int len;

	if (m->count < m->size) {
		va_start(args, f);
		len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
		va_end(args);
		if (m->count + len < m->size) {
			m->count += len;
			return 0;
		}
	}
	m->count = m->size;
	return -1;
}
EXPORT_SYMBOL(seq_printf);

int seq_path(struct seq_file *m, struct path *path, char *esc)
{
	if (m->count < m->size) {
		char *s = m->buf + m->count;
		char *p = d_path(path, s, m->size - m->count);
		if (!IS_ERR(p)) {
			while (s <= p) {
				char c = *p++;
				if (!c) {
					p = m->buf + m->count;
					m->count = s - m->buf;
					return s - p;
				} else if (!strchr(esc, c)) {
					*s++ = c;
				} else if (s + 4 > p) {
					break;
				} else {
					*s++ = '\\';
					*s++ = '0' + ((c & 0300) >> 6);
					*s++ = '0' + ((c & 070) >> 3);
					*s++ = '0' + (c & 07);
				}
			}
		}
	}
	m->count = m->size;
	return -1;
}
EXPORT_SYMBOL(seq_path);

static void *single_start(struct seq_file *p, loff_t *pos)
{
	return NULL + (*pos == 0);
}

static void *single_next(struct seq_file *p, void *v, loff_t *pos)
{
	++*pos;
	return NULL;
}

static void single_stop(struct seq_file *p, void *v)
{
}

int single_open(struct file *file, int (*show)(struct seq_file *, void *),
		void *data)
{
	struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL);
	int res = -ENOMEM;

	if (op) {
		op->start = single_start;
		op->next = single_next;
		op->stop = single_stop;
		op->show = show;
		res = seq_open(file, op);
		if (!res)
			((struct seq_file *)file->private_data)->private = data;
		else
			kfree(op);
	}
	return res;
}
EXPORT_SYMBOL(single_open);

int single_release(struct inode *inode, struct file *file)
{
	const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
	int res = seq_release(inode, file);
	kfree(op);
	return res;
}
EXPORT_SYMBOL(single_release);

int seq_release_private(struct inode *inode, struct file *file)
{
	struct seq_file *seq = file->private_data;

	kfree(seq->private);
	seq->private = NULL;
	return seq_release(inode, file);
}
EXPORT_SYMBOL(seq_release_private);

void *__seq_open_private(struct file *f, const struct seq_operations *ops,
		int psize)
{
	int rc;
	void *private;
	struct seq_file *seq;

	private = kzalloc(psize, GFP_KERNEL);
	if (private == NULL)
		goto out;

	rc = seq_open(f, ops);
	if (rc < 0)
		goto out_free;

	seq = f->private_data;
	seq->private = private;
	return private;

out_free:
	kfree(private);
out:
	return NULL;
}
EXPORT_SYMBOL(__seq_open_private);

int seq_open_private(struct file *filp, const struct seq_operations *ops,
		int psize)
{
	return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM;
}
EXPORT_SYMBOL(seq_open_private);

int seq_putc(struct seq_file *m, char c)
{
	if (m->count < m->size) {
		m->buf[m->count++] = c;
		return 0;
	}
	return -1;
}
EXPORT_SYMBOL(seq_putc);

int seq_puts(struct seq_file *m, const char *s)
{
	int len = strlen(s);
	if (m->count + len < m->size) {
		memcpy(m->buf + m->count, s, len);
		m->count += len;
		return 0;
	}
	m->count = m->size;
	return -1;
}
EXPORT_SYMBOL(seq_puts);

struct list_head *seq_list_start(struct list_head *head, loff_t pos)
{
	struct list_head *lh;

	list_for_each(lh, head)
		if (pos-- == 0)
			return lh;

	return NULL;
}

EXPORT_SYMBOL(seq_list_start);

struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
{
	if (!pos)
		return head;

	return seq_list_start(head, pos - 1);
}

EXPORT_SYMBOL(seq_list_start_head);

struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
{
	struct list_head *lh;

	lh = ((struct list_head *)v)->next;
	++*ppos;
	return lh == head ? NULL : lh;
}

EXPORT_SYMBOL(seq_list_next);