4 * helper functions for making synthetic files from sequences of records.
5 * initial implementation -- AV, Oct 2001.
9 #include <linux/module.h>
10 #include <linux/seq_file.h>
11 #include <linux/slab.h>
13 #include <asm/uaccess.h>
17 * seq_open - initialize sequential file
18 * @file: file we initialize
19 * @op: method table describing the sequence
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.
29 int seq_open(struct file *file, const struct seq_operations *op)
31 struct seq_file *p = file->private_data;
34 p = kmalloc(sizeof(*p), GFP_KERNEL);
37 file->private_data = p;
39 memset(p, 0, sizeof(*p));
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.
50 /* SEQ files support lseek, but not pread/pwrite */
51 file->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
54 EXPORT_SYMBOL(seq_open);
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
63 * Ready-made ->f_op->read()
65 ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
67 struct seq_file *m = (struct seq_file *)file->private_data;
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.
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.
86 m->version = file->f_version;
87 /* grab buffer if we didn't have one */
89 m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
93 /* if not empty - flush it first */
95 n = min(m->count, size);
96 err = copy_to_user(buf, m->buf + m->from, n);
109 /* we need at least one record in buffer */
112 p = m->op->start(m, &pos);
116 err = m->op->show(m, p);
119 if (m->count < m->size)
123 m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
133 /* they want more? let's try to get some more */
134 while (m->count < size) {
135 size_t offs = m->count;
137 p = m->op->next(m, p, &next);
138 if (!p || IS_ERR(p)) {
142 err = m->op->show(m, p);
143 if (err || m->count == m->size) {
150 n = min(m->count, size);
151 err = copy_to_user(buf, m->buf, n);
166 file->f_version = m->version;
167 mutex_unlock(&m->lock);
176 EXPORT_SYMBOL(seq_read);
178 static int traverse(struct seq_file *m, loff_t offset)
186 m->count = m->from = 0;
190 m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
194 p = m->op->start(m, &m->index);
199 error = m->op->show(m, p);
202 if (m->count == m->size)
204 if (pos + m->count > offset) {
205 m->from = offset - pos;
215 p = m->op->next(m, p, &m->index);
223 m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
224 return !m->buf ? -ENOMEM : -EAGAIN;
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
233 * Ready-made ->f_op->llseek()
235 loff_t seq_lseek(struct file *file, loff_t offset, int origin)
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;
244 offset += file->f_pos;
249 if (offset != file->f_pos) {
250 while ((retval=traverse(m, offset)) == -EAGAIN)
253 /* with extreme prejudice... */
259 retval = file->f_pos = offset;
263 mutex_unlock(&m->lock);
264 file->f_version = m->version;
267 EXPORT_SYMBOL(seq_lseek);
270 * seq_release - free the structures associated with sequential file.
271 * @file: file in question
272 * @inode: file->f_path.dentry->d_inode
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.
277 int seq_release(struct inode *inode, struct file *file)
279 struct seq_file *m = (struct seq_file *)file->private_data;
284 EXPORT_SYMBOL(seq_release);
287 * seq_escape - print string into buffer, escaping some characters
290 * @esc: set of characters that need escaping
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
296 int seq_escape(struct seq_file *m, const char *s, const char *esc)
298 char *end = m->buf + m->size;
302 for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) {
303 if (!strchr(esc, c)) {
309 *p++ = '0' + ((c & 0300) >> 6);
310 *p++ = '0' + ((c & 070) >> 3);
311 *p++ = '0' + (c & 07);
317 m->count = p - m->buf;
320 EXPORT_SYMBOL(seq_escape);
322 int seq_printf(struct seq_file *m, const char *f, ...)
327 if (m->count < m->size) {
329 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
331 if (m->count + len < m->size) {
339 EXPORT_SYMBOL(seq_printf);
341 int seq_path(struct seq_file *m,
342 struct vfsmount *mnt, struct dentry *dentry,
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);
352 p = m->buf + m->count;
353 m->count = s - m->buf;
355 } else if (!strchr(esc, c)) {
357 } else if (s + 4 > p) {
361 *s++ = '0' + ((c & 0300) >> 6);
362 *s++ = '0' + ((c & 070) >> 3);
363 *s++ = '0' + (c & 07);
371 EXPORT_SYMBOL(seq_path);
373 static void *single_start(struct seq_file *p, loff_t *pos)
375 return NULL + (*pos == 0);
378 static void *single_next(struct seq_file *p, void *v, loff_t *pos)
384 static void single_stop(struct seq_file *p, void *v)
388 int single_open(struct file *file, int (*show)(struct seq_file *, void *),
391 struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL);
395 op->start = single_start;
396 op->next = single_next;
397 op->stop = single_stop;
399 res = seq_open(file, op);
401 ((struct seq_file *)file->private_data)->private = data;
407 EXPORT_SYMBOL(single_open);
409 int single_release(struct inode *inode, struct file *file)
411 const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
412 int res = seq_release(inode, file);
416 EXPORT_SYMBOL(single_release);
418 int seq_release_private(struct inode *inode, struct file *file)
420 struct seq_file *seq = file->private_data;
424 return seq_release(inode, file);
426 EXPORT_SYMBOL(seq_release_private);
428 int seq_putc(struct seq_file *m, char c)
430 if (m->count < m->size) {
431 m->buf[m->count++] = c;
436 EXPORT_SYMBOL(seq_putc);
438 int seq_puts(struct seq_file *m, const char *s)
441 if (m->count + len < m->size) {
442 memcpy(m->buf + m->count, s, len);
449 EXPORT_SYMBOL(seq_puts);