ia64/linux-2.6.18-xen.hg

view fs/seq_file.c @ 524:7f8b544237bf

netfront: Allow netfront in domain 0.

This is useful if your physical network device is in a utility domain.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Tue Apr 15 15:18:58 2008 +0100 (2008-04-15)
parents 831230e53067
children
line source
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 */
8 #include <linux/fs.h>
9 #include <linux/module.h>
10 #include <linux/seq_file.h>
11 #include <linux/slab.h>
13 #include <asm/uaccess.h>
14 #include <asm/page.h>
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 = file->private_data;
33 if (!p) {
34 p = kmalloc(sizeof(*p), GFP_KERNEL);
35 if (!p)
36 return -ENOMEM;
37 file->private_data = p;
38 }
39 memset(p, 0, sizeof(*p));
40 mutex_init(&p->lock);
41 p->op = op;
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;
50 /* SEQ files support lseek, but not pread/pwrite */
51 file->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
52 return 0;
53 }
54 EXPORT_SYMBOL(seq_open);
56 /**
57 * seq_read - ->read() method for sequential files.
58 * @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
62 *
63 * Ready-made ->f_op->read()
64 */
65 ssize_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;
74 mutex_lock(&m->lock);
75 /*
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;
132 Fill:
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;
161 Done:
162 if (!copied)
163 copied = err;
164 else
165 *ppos += copied;
166 file->f_version = m->version;
167 mutex_unlock(&m->lock);
168 return copied;
169 Enomem:
170 err = -ENOMEM;
171 goto Done;
172 Efault:
173 err = -EFAULT;
174 goto Done;
175 }
176 EXPORT_SYMBOL(seq_read);
178 static int traverse(struct seq_file *m, loff_t offset)
179 {
180 loff_t pos = 0;
181 int error = 0;
182 void *p;
184 m->version = 0;
185 m->index = 0;
186 m->count = m->from = 0;
187 if (!offset)
188 return 0;
189 if (!m->buf) {
190 m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
191 if (!m->buf)
192 return -ENOMEM;
193 }
194 p = m->op->start(m, &m->index);
195 while (p) {
196 error = PTR_ERR(p);
197 if (IS_ERR(p))
198 break;
199 error = m->op->show(m, p);
200 if (error)
201 break;
202 if (m->count == m->size)
203 goto Eoverflow;
204 if (pos + m->count > offset) {
205 m->from = offset - pos;
206 m->count -= m->from;
207 break;
208 }
209 pos += m->count;
210 m->count = 0;
211 if (pos == offset) {
212 m->index++;
213 break;
214 }
215 p = m->op->next(m, p, &m->index);
216 }
217 m->op->stop(m, p);
218 return error;
220 Eoverflow:
221 m->op->stop(m, p);
222 kfree(m->buf);
223 m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
224 return !m->buf ? -ENOMEM : -EAGAIN;
225 }
227 /**
228 * seq_lseek - ->llseek() method for sequential files.
229 * @file: the file in question
230 * @offset: new position
231 * @origin: 0 for absolute, 1 for relative position
232 *
233 * Ready-made ->f_op->llseek()
234 */
235 loff_t seq_lseek(struct file *file, loff_t offset, int origin)
236 {
237 struct seq_file *m = (struct seq_file *)file->private_data;
238 long long retval = -EINVAL;
240 mutex_lock(&m->lock);
241 m->version = file->f_version;
242 switch (origin) {
243 case 1:
244 offset += file->f_pos;
245 case 0:
246 if (offset < 0)
247 break;
248 retval = offset;
249 if (offset != file->f_pos) {
250 while ((retval=traverse(m, offset)) == -EAGAIN)
251 ;
252 if (retval) {
253 /* with extreme prejudice... */
254 file->f_pos = 0;
255 m->version = 0;
256 m->index = 0;
257 m->count = 0;
258 } else {
259 retval = file->f_pos = offset;
260 }
261 }
262 }
263 mutex_unlock(&m->lock);
264 file->f_version = m->version;
265 return retval;
266 }
267 EXPORT_SYMBOL(seq_lseek);
269 /**
270 * seq_release - free the structures associated with sequential file.
271 * @file: file in question
272 * @inode: file->f_dentry->d_inode
273 *
274 * Frees the structures associated with sequential file; can be used
275 * as ->f_op->release() if you don't have private data to destroy.
276 */
277 int seq_release(struct inode *inode, struct file *file)
278 {
279 struct seq_file *m = (struct seq_file *)file->private_data;
280 kfree(m->buf);
281 kfree(m);
282 return 0;
283 }
284 EXPORT_SYMBOL(seq_release);
286 /**
287 * seq_escape - print string into buffer, escaping some characters
288 * @m: target buffer
289 * @s: string
290 * @esc: set of characters that need escaping
291 *
292 * Puts string into buffer, replacing each occurrence of character from
293 * @esc with usual octal escape. Returns 0 in case of success, -1 - in
294 * case of overflow.
295 */
296 int seq_escape(struct seq_file *m, const char *s, const char *esc)
297 {
298 char *end = m->buf + m->size;
299 char *p;
300 char c;
302 for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) {
303 if (!strchr(esc, c)) {
304 *p++ = c;
305 continue;
306 }
307 if (p + 3 < end) {
308 *p++ = '\\';
309 *p++ = '0' + ((c & 0300) >> 6);
310 *p++ = '0' + ((c & 070) >> 3);
311 *p++ = '0' + (c & 07);
312 continue;
313 }
314 m->count = m->size;
315 return -1;
316 }
317 m->count = p - m->buf;
318 return 0;
319 }
320 EXPORT_SYMBOL(seq_escape);
322 int seq_printf(struct seq_file *m, const char *f, ...)
323 {
324 va_list args;
325 int len;
327 if (m->count < m->size) {
328 va_start(args, f);
329 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
330 va_end(args);
331 if (m->count + len < m->size) {
332 m->count += len;
333 return 0;
334 }
335 }
336 m->count = m->size;
337 return -1;
338 }
339 EXPORT_SYMBOL(seq_printf);
341 int seq_path(struct seq_file *m,
342 struct vfsmount *mnt, struct dentry *dentry,
343 char *esc)
344 {
345 if (m->count < m->size) {
346 char *s = m->buf + m->count;
347 char *p = d_path(dentry, mnt, s, m->size - m->count);
348 if (!IS_ERR(p)) {
349 while (s <= p) {
350 char c = *p++;
351 if (!c) {
352 p = m->buf + m->count;
353 m->count = s - m->buf;
354 return s - p;
355 } else if (!strchr(esc, c)) {
356 *s++ = c;
357 } else if (s + 4 > p) {
358 break;
359 } else {
360 *s++ = '\\';
361 *s++ = '0' + ((c & 0300) >> 6);
362 *s++ = '0' + ((c & 070) >> 3);
363 *s++ = '0' + (c & 07);
364 }
365 }
366 }
367 }
368 m->count = m->size;
369 return -1;
370 }
371 EXPORT_SYMBOL(seq_path);
373 static void *single_start(struct seq_file *p, loff_t *pos)
374 {
375 return NULL + (*pos == 0);
376 }
378 static void *single_next(struct seq_file *p, void *v, loff_t *pos)
379 {
380 ++*pos;
381 return NULL;
382 }
384 static void single_stop(struct seq_file *p, void *v)
385 {
386 }
388 int single_open(struct file *file, int (*show)(struct seq_file *, void *),
389 void *data)
390 {
391 struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL);
392 int res = -ENOMEM;
394 if (op) {
395 op->start = single_start;
396 op->next = single_next;
397 op->stop = single_stop;
398 op->show = show;
399 res = seq_open(file, op);
400 if (!res)
401 ((struct seq_file *)file->private_data)->private = data;
402 else
403 kfree(op);
404 }
405 return res;
406 }
407 EXPORT_SYMBOL(single_open);
409 int single_release(struct inode *inode, struct file *file)
410 {
411 struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
412 int res = seq_release(inode, file);
413 kfree(op);
414 return res;
415 }
416 EXPORT_SYMBOL(single_release);
418 int seq_release_private(struct inode *inode, struct file *file)
419 {
420 struct seq_file *seq = file->private_data;
422 kfree(seq->private);
423 seq->private = NULL;
424 return seq_release(inode, file);
425 }
426 EXPORT_SYMBOL(seq_release_private);
428 int seq_putc(struct seq_file *m, char c)
429 {
430 if (m->count < m->size) {
431 m->buf[m->count++] = c;
432 return 0;
433 }
434 return -1;
435 }
436 EXPORT_SYMBOL(seq_putc);
438 int seq_puts(struct seq_file *m, const char *s)
439 {
440 int len = strlen(s);
441 if (m->count + len < m->size) {
442 memcpy(m->buf + m->count, s, len);
443 m->count += len;
444 return 0;
445 }
446 m->count = m->size;
447 return -1;
448 }
449 EXPORT_SYMBOL(seq_puts);