4 * helper functions for making synthetic files from sequences of records.
5 * initial implementation -- AV, Oct 2001.
9 #include <linux/seq_file.h>
10 #include <linux/slab.h>
12 #include <asm/uaccess.h>
16 * seq_open - initialize sequential file
17 * @file: file we initialize
18 * @op: method table describing the sequence
20 * seq_open() sets @file, associating it with a sequence described
21 * by @op. @op->start() sets the iterator up and returns the first
22 * element of sequence. @op->stop() shuts it down. @op->next()
23 * returns the next element of sequence. @op->show() prints element
24 * into the buffer. In case of error ->start() and ->next() return
25 * ERR_PTR(error). In the end of sequence they return %NULL. ->show()
26 * returns 0 in case of success and negative number in case of error.
28 int seq_open(struct file *file, struct seq_operations *op)
30 struct seq_file *p = kmalloc(sizeof(*p), GFP_KERNEL);
33 memset(p, 0, sizeof(*p));
34 sema_init(&p->sem, 1);
36 file->private_data = p;
41 * seq_read - ->read() method for sequential files.
42 * @file, @buf, @size, @ppos: see file_operations method
44 * Ready-made ->f_op->read()
46 ssize_t seq_read(struct file *file, char *buf, size_t size, loff_t *ppos)
48 struct seq_file *m = (struct seq_file *)file->private_data;
55 if (ppos != &file->f_pos)
59 /* grab buffer if we didn't have one */
61 m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
65 /* if not empty - flush it first */
67 n = min(m->count, size);
68 err = copy_to_user(buf, m->buf + m->from, n);
81 /* we need at least one record in buffer */
84 p = m->op->start(m, &pos);
88 err = m->op->show(m, p);
91 if (m->count < m->size)
95 m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
104 /* they want more? let's try to get some more */
105 while (m->count < size) {
106 size_t offs = m->count;
108 p = m->op->next(m, p, &next);
109 if (!p || IS_ERR(p)) {
113 err = m->op->show(m, p);
114 if (err || m->count == m->size) {
121 n = min(m->count, size);
122 err = copy_to_user(buf, m->buf, n);
147 static int traverse(struct seq_file *m, loff_t offset)
154 m->count = m->from = 0;
158 m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
162 p = m->op->start(m, &m->index);
167 error = m->op->show(m, p);
170 if (m->count == m->size)
172 if (pos + m->count > offset) {
173 m->from = offset - pos;
183 p = m->op->next(m, p, &m->index);
191 m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
192 return !m->buf ? -ENOMEM : -EAGAIN;
196 * seq_lseek - ->llseek() method for sequential files.
197 * @file, @offset, @origin: see file_operations method
199 * Ready-made ->f_op->llseek()
201 loff_t seq_lseek(struct file *file, loff_t offset, int origin)
203 struct seq_file *m = (struct seq_file *)file->private_data;
204 long long retval = -EINVAL;
209 offset += file->f_pos;
214 if (offset != file->f_pos) {
215 while ((retval=traverse(m, offset)) == -EAGAIN)
218 /* with extreme prejudice... */
223 retval = file->f_pos = offset;
232 * seq_release - free the structures associated with sequential file.
233 * @file: file in question
234 * @inode: file->f_dentry->d_inode
236 * Frees the structures associated with sequential file; can be used
237 * as ->f_op->release() if you don't have private data to destroy.
239 int seq_release(struct inode *inode, struct file *file)
241 struct seq_file *m = (struct seq_file *)file->private_data;
248 * seq_escape - print string into buffer, escaping some characters
251 * @esc: set of characters that need escaping
253 * Puts string into buffer, replacing each occurrence of character from
254 * @esc with usual octal escape. Returns 0 in case of success, -1 - in
257 int seq_escape(struct seq_file *m, const char *s, const char *esc)
259 char *end = m->buf + m->size;
263 for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) {
264 if (!strchr(esc, c)) {
270 *p++ = '0' + ((c & 0300) >> 6);
271 *p++ = '0' + ((c & 070) >> 3);
272 *p++ = '0' + (c & 07);
278 m->count = p - m->buf;
282 int seq_printf(struct seq_file *m, const char *f, ...)
287 if (m->count < m->size) {
289 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
291 if (m->count + len < m->size) {
300 int seq_path(struct seq_file *m,
301 struct vfsmount *mnt, struct dentry *dentry,
304 if (m->count < m->size) {
305 char *s = m->buf + m->count;
306 char *p = d_path(dentry, mnt, s, m->size - m->count);
311 p = m->buf + m->count;
312 m->count = s - m->buf;
314 } else if (!strchr(esc, c)) {
316 } else if (s + 4 > p) {
320 *s++ = '0' + ((c & 0300) >> 6);
321 *s++ = '0' + ((c & 070) >> 3);
322 *s++ = '0' + (c & 07);
331 static void *single_start(struct seq_file *p, loff_t *pos)
333 return NULL + (*pos == 0);
336 static void *single_next(struct seq_file *p, void *v, loff_t *pos)
342 static void single_stop(struct seq_file *p, void *v)
346 int single_open(struct file *file, int (*show)(struct seq_file *, void*), void *data)
348 struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL);
352 op->start = single_start;
353 op->next = single_next;
354 op->stop = single_stop;
356 res = seq_open(file, op);
358 ((struct seq_file *)file->private_data)->private = data;
365 int single_release(struct inode *inode, struct file *file)
367 struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
368 int res = seq_release(inode, file);
373 int seq_release_private(struct inode *inode, struct file *file)
375 struct seq_file *seq = file->private_data;
379 return seq_release(inode, file);