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1da177e4 LT |
1 | /* |
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 | */ | |
29 | int seq_open(struct file *file, struct seq_operations *op) | |
30 | { | |
31 | struct seq_file *p = kmalloc(sizeof(*p), GFP_KERNEL); | |
32 | if (!p) | |
33 | return -ENOMEM; | |
34 | memset(p, 0, sizeof(*p)); | |
35 | sema_init(&p->sem, 1); | |
36 | p->op = op; | |
37 | file->private_data = p; | |
38 | ||
39 | /* | |
40 | * Wrappers around seq_open(e.g. swaps_open) need to be | |
41 | * aware of this. If they set f_version themselves, they | |
42 | * should call seq_open first and then set f_version. | |
43 | */ | |
44 | file->f_version = 0; | |
45 | ||
46 | /* SEQ files support lseek, but not pread/pwrite */ | |
47 | file->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE); | |
48 | return 0; | |
49 | } | |
50 | EXPORT_SYMBOL(seq_open); | |
51 | ||
52 | /** | |
53 | * seq_read - ->read() method for sequential files. | |
67be2dd1 MW |
54 | * @file: the file to read from |
55 | * @buf: the buffer to read to | |
56 | * @size: the maximum number of bytes to read | |
57 | * @ppos: the current position in the file | |
1da177e4 LT |
58 | * |
59 | * Ready-made ->f_op->read() | |
60 | */ | |
61 | ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) | |
62 | { | |
63 | struct seq_file *m = (struct seq_file *)file->private_data; | |
64 | size_t copied = 0; | |
65 | loff_t pos; | |
66 | size_t n; | |
67 | void *p; | |
68 | int err = 0; | |
69 | ||
70 | down(&m->sem); | |
71 | /* | |
72 | * seq_file->op->..m_start/m_stop/m_next may do special actions | |
73 | * or optimisations based on the file->f_version, so we want to | |
74 | * pass the file->f_version to those methods. | |
75 | * | |
76 | * seq_file->version is just copy of f_version, and seq_file | |
77 | * methods can treat it simply as file version. | |
78 | * It is copied in first and copied out after all operations. | |
79 | * It is convenient to have it as part of structure to avoid the | |
80 | * need of passing another argument to all the seq_file methods. | |
81 | */ | |
82 | m->version = file->f_version; | |
83 | /* grab buffer if we didn't have one */ | |
84 | if (!m->buf) { | |
85 | m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL); | |
86 | if (!m->buf) | |
87 | goto Enomem; | |
88 | } | |
89 | /* if not empty - flush it first */ | |
90 | if (m->count) { | |
91 | n = min(m->count, size); | |
92 | err = copy_to_user(buf, m->buf + m->from, n); | |
93 | if (err) | |
94 | goto Efault; | |
95 | m->count -= n; | |
96 | m->from += n; | |
97 | size -= n; | |
98 | buf += n; | |
99 | copied += n; | |
100 | if (!m->count) | |
101 | m->index++; | |
102 | if (!size) | |
103 | goto Done; | |
104 | } | |
105 | /* we need at least one record in buffer */ | |
106 | while (1) { | |
107 | pos = m->index; | |
108 | p = m->op->start(m, &pos); | |
109 | err = PTR_ERR(p); | |
110 | if (!p || IS_ERR(p)) | |
111 | break; | |
112 | err = m->op->show(m, p); | |
113 | if (err) | |
114 | break; | |
115 | if (m->count < m->size) | |
116 | goto Fill; | |
117 | m->op->stop(m, p); | |
118 | kfree(m->buf); | |
119 | m->buf = kmalloc(m->size <<= 1, GFP_KERNEL); | |
120 | if (!m->buf) | |
121 | goto Enomem; | |
122 | m->count = 0; | |
123 | m->version = 0; | |
124 | } | |
125 | m->op->stop(m, p); | |
126 | m->count = 0; | |
127 | goto Done; | |
128 | Fill: | |
129 | /* they want more? let's try to get some more */ | |
130 | while (m->count < size) { | |
131 | size_t offs = m->count; | |
132 | loff_t next = pos; | |
133 | p = m->op->next(m, p, &next); | |
134 | if (!p || IS_ERR(p)) { | |
135 | err = PTR_ERR(p); | |
136 | break; | |
137 | } | |
138 | err = m->op->show(m, p); | |
139 | if (err || m->count == m->size) { | |
140 | m->count = offs; | |
141 | break; | |
142 | } | |
143 | pos = next; | |
144 | } | |
145 | m->op->stop(m, p); | |
146 | n = min(m->count, size); | |
147 | err = copy_to_user(buf, m->buf, n); | |
148 | if (err) | |
149 | goto Efault; | |
150 | copied += n; | |
151 | m->count -= n; | |
152 | if (m->count) | |
153 | m->from = n; | |
154 | else | |
155 | pos++; | |
156 | m->index = pos; | |
157 | Done: | |
158 | if (!copied) | |
159 | copied = err; | |
160 | else | |
161 | *ppos += copied; | |
162 | file->f_version = m->version; | |
163 | up(&m->sem); | |
164 | return copied; | |
165 | Enomem: | |
166 | err = -ENOMEM; | |
167 | goto Done; | |
168 | Efault: | |
169 | err = -EFAULT; | |
170 | goto Done; | |
171 | } | |
172 | EXPORT_SYMBOL(seq_read); | |
173 | ||
174 | static int traverse(struct seq_file *m, loff_t offset) | |
175 | { | |
176 | loff_t pos = 0; | |
177 | int error = 0; | |
178 | void *p; | |
179 | ||
180 | m->version = 0; | |
181 | m->index = 0; | |
182 | m->count = m->from = 0; | |
183 | if (!offset) | |
184 | return 0; | |
185 | if (!m->buf) { | |
186 | m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL); | |
187 | if (!m->buf) | |
188 | return -ENOMEM; | |
189 | } | |
190 | p = m->op->start(m, &m->index); | |
191 | while (p) { | |
192 | error = PTR_ERR(p); | |
193 | if (IS_ERR(p)) | |
194 | break; | |
195 | error = m->op->show(m, p); | |
196 | if (error) | |
197 | break; | |
198 | if (m->count == m->size) | |
199 | goto Eoverflow; | |
200 | if (pos + m->count > offset) { | |
201 | m->from = offset - pos; | |
202 | m->count -= m->from; | |
203 | break; | |
204 | } | |
205 | pos += m->count; | |
206 | m->count = 0; | |
207 | if (pos == offset) { | |
208 | m->index++; | |
209 | break; | |
210 | } | |
211 | p = m->op->next(m, p, &m->index); | |
212 | } | |
213 | m->op->stop(m, p); | |
214 | return error; | |
215 | ||
216 | Eoverflow: | |
217 | m->op->stop(m, p); | |
218 | kfree(m->buf); | |
219 | m->buf = kmalloc(m->size <<= 1, GFP_KERNEL); | |
220 | return !m->buf ? -ENOMEM : -EAGAIN; | |
221 | } | |
222 | ||
223 | /** | |
224 | * seq_lseek - ->llseek() method for sequential files. | |
67be2dd1 MW |
225 | * @file: the file in question |
226 | * @offset: new position | |
227 | * @origin: 0 for absolute, 1 for relative position | |
1da177e4 LT |
228 | * |
229 | * Ready-made ->f_op->llseek() | |
230 | */ | |
231 | loff_t seq_lseek(struct file *file, loff_t offset, int origin) | |
232 | { | |
233 | struct seq_file *m = (struct seq_file *)file->private_data; | |
234 | long long retval = -EINVAL; | |
235 | ||
236 | down(&m->sem); | |
237 | m->version = file->f_version; | |
238 | switch (origin) { | |
239 | case 1: | |
240 | offset += file->f_pos; | |
241 | case 0: | |
242 | if (offset < 0) | |
243 | break; | |
244 | retval = offset; | |
245 | if (offset != file->f_pos) { | |
246 | while ((retval=traverse(m, offset)) == -EAGAIN) | |
247 | ; | |
248 | if (retval) { | |
249 | /* with extreme prejudice... */ | |
250 | file->f_pos = 0; | |
251 | m->version = 0; | |
252 | m->index = 0; | |
253 | m->count = 0; | |
254 | } else { | |
255 | retval = file->f_pos = offset; | |
256 | } | |
257 | } | |
258 | } | |
259 | up(&m->sem); | |
260 | file->f_version = m->version; | |
261 | return retval; | |
262 | } | |
263 | EXPORT_SYMBOL(seq_lseek); | |
264 | ||
265 | /** | |
266 | * seq_release - free the structures associated with sequential file. | |
267 | * @file: file in question | |
268 | * @inode: file->f_dentry->d_inode | |
269 | * | |
270 | * Frees the structures associated with sequential file; can be used | |
271 | * as ->f_op->release() if you don't have private data to destroy. | |
272 | */ | |
273 | int seq_release(struct inode *inode, struct file *file) | |
274 | { | |
275 | struct seq_file *m = (struct seq_file *)file->private_data; | |
276 | kfree(m->buf); | |
277 | kfree(m); | |
278 | return 0; | |
279 | } | |
280 | EXPORT_SYMBOL(seq_release); | |
281 | ||
282 | /** | |
283 | * seq_escape - print string into buffer, escaping some characters | |
284 | * @m: target buffer | |
285 | * @s: string | |
286 | * @esc: set of characters that need escaping | |
287 | * | |
288 | * Puts string into buffer, replacing each occurrence of character from | |
289 | * @esc with usual octal escape. Returns 0 in case of success, -1 - in | |
290 | * case of overflow. | |
291 | */ | |
292 | int seq_escape(struct seq_file *m, const char *s, const char *esc) | |
293 | { | |
294 | char *end = m->buf + m->size; | |
295 | char *p; | |
296 | char c; | |
297 | ||
298 | for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) { | |
299 | if (!strchr(esc, c)) { | |
300 | *p++ = c; | |
301 | continue; | |
302 | } | |
303 | if (p + 3 < end) { | |
304 | *p++ = '\\'; | |
305 | *p++ = '0' + ((c & 0300) >> 6); | |
306 | *p++ = '0' + ((c & 070) >> 3); | |
307 | *p++ = '0' + (c & 07); | |
308 | continue; | |
309 | } | |
310 | m->count = m->size; | |
311 | return -1; | |
312 | } | |
313 | m->count = p - m->buf; | |
314 | return 0; | |
315 | } | |
316 | EXPORT_SYMBOL(seq_escape); | |
317 | ||
318 | int seq_printf(struct seq_file *m, const char *f, ...) | |
319 | { | |
320 | va_list args; | |
321 | int len; | |
322 | ||
323 | if (m->count < m->size) { | |
324 | va_start(args, f); | |
325 | len = vsnprintf(m->buf + m->count, m->size - m->count, f, args); | |
326 | va_end(args); | |
327 | if (m->count + len < m->size) { | |
328 | m->count += len; | |
329 | return 0; | |
330 | } | |
331 | } | |
332 | m->count = m->size; | |
333 | return -1; | |
334 | } | |
335 | EXPORT_SYMBOL(seq_printf); | |
336 | ||
337 | int seq_path(struct seq_file *m, | |
338 | struct vfsmount *mnt, struct dentry *dentry, | |
339 | char *esc) | |
340 | { | |
341 | if (m->count < m->size) { | |
342 | char *s = m->buf + m->count; | |
343 | char *p = d_path(dentry, mnt, s, m->size - m->count); | |
344 | if (!IS_ERR(p)) { | |
345 | while (s <= p) { | |
346 | char c = *p++; | |
347 | if (!c) { | |
348 | p = m->buf + m->count; | |
349 | m->count = s - m->buf; | |
350 | return s - p; | |
351 | } else if (!strchr(esc, c)) { | |
352 | *s++ = c; | |
353 | } else if (s + 4 > p) { | |
354 | break; | |
355 | } else { | |
356 | *s++ = '\\'; | |
357 | *s++ = '0' + ((c & 0300) >> 6); | |
358 | *s++ = '0' + ((c & 070) >> 3); | |
359 | *s++ = '0' + (c & 07); | |
360 | } | |
361 | } | |
362 | } | |
363 | } | |
364 | m->count = m->size; | |
365 | return -1; | |
366 | } | |
367 | EXPORT_SYMBOL(seq_path); | |
368 | ||
369 | static void *single_start(struct seq_file *p, loff_t *pos) | |
370 | { | |
371 | return NULL + (*pos == 0); | |
372 | } | |
373 | ||
374 | static void *single_next(struct seq_file *p, void *v, loff_t *pos) | |
375 | { | |
376 | ++*pos; | |
377 | return NULL; | |
378 | } | |
379 | ||
380 | static void single_stop(struct seq_file *p, void *v) | |
381 | { | |
382 | } | |
383 | ||
384 | int single_open(struct file *file, int (*show)(struct seq_file *, void *), | |
385 | void *data) | |
386 | { | |
387 | struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL); | |
388 | int res = -ENOMEM; | |
389 | ||
390 | if (op) { | |
391 | op->start = single_start; | |
392 | op->next = single_next; | |
393 | op->stop = single_stop; | |
394 | op->show = show; | |
395 | res = seq_open(file, op); | |
396 | if (!res) | |
397 | ((struct seq_file *)file->private_data)->private = data; | |
398 | else | |
399 | kfree(op); | |
400 | } | |
401 | return res; | |
402 | } | |
403 | EXPORT_SYMBOL(single_open); | |
404 | ||
405 | int single_release(struct inode *inode, struct file *file) | |
406 | { | |
407 | struct seq_operations *op = ((struct seq_file *)file->private_data)->op; | |
408 | int res = seq_release(inode, file); | |
409 | kfree(op); | |
410 | return res; | |
411 | } | |
412 | EXPORT_SYMBOL(single_release); | |
413 | ||
414 | int seq_release_private(struct inode *inode, struct file *file) | |
415 | { | |
416 | struct seq_file *seq = file->private_data; | |
417 | ||
418 | kfree(seq->private); | |
419 | seq->private = NULL; | |
420 | return seq_release(inode, file); | |
421 | } | |
422 | EXPORT_SYMBOL(seq_release_private); | |
423 | ||
424 | int seq_putc(struct seq_file *m, char c) | |
425 | { | |
426 | if (m->count < m->size) { | |
427 | m->buf[m->count++] = c; | |
428 | return 0; | |
429 | } | |
430 | return -1; | |
431 | } | |
432 | EXPORT_SYMBOL(seq_putc); | |
433 | ||
434 | int seq_puts(struct seq_file *m, const char *s) | |
435 | { | |
436 | int len = strlen(s); | |
437 | if (m->count + len < m->size) { | |
438 | memcpy(m->buf + m->count, s, len); | |
439 | m->count += len; | |
440 | return 0; | |
441 | } | |
442 | m->count = m->size; | |
443 | return -1; | |
444 | } | |
445 | EXPORT_SYMBOL(seq_puts); |