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.
28 * Returning SEQ_SKIP means "discard this element and move on".
30 int seq_open(struct file
*file
, const struct seq_operations
*op
)
32 struct seq_file
*p
= file
->private_data
;
35 p
= kmalloc(sizeof(*p
), GFP_KERNEL
);
38 file
->private_data
= p
;
40 memset(p
, 0, sizeof(*p
));
45 * Wrappers around seq_open(e.g. swaps_open) need to be
46 * aware of this. If they set f_version themselves, they
47 * should call seq_open first and then set f_version.
52 * seq_files support lseek() and pread(). They do not implement
53 * write() at all, but we clear FMODE_PWRITE here for historical
56 * If a client of seq_files a) implements file.write() and b) wishes to
57 * support pwrite() then that client will need to implement its own
58 * file.open() which calls seq_open() and then sets FMODE_PWRITE.
60 file
->f_mode
&= ~FMODE_PWRITE
;
63 EXPORT_SYMBOL(seq_open
);
65 static int traverse(struct seq_file
*m
, loff_t offset
)
67 loff_t pos
= 0, index
;
73 m
->count
= m
->from
= 0;
79 m
->buf
= kmalloc(m
->size
= PAGE_SIZE
, GFP_KERNEL
);
83 p
= m
->op
->start(m
, &index
);
88 error
= m
->op
->show(m
, p
);
91 if (unlikely(error
)) {
95 if (m
->count
== m
->size
)
97 if (pos
+ m
->count
> offset
) {
98 m
->from
= offset
- pos
;
110 p
= m
->op
->next(m
, p
, &index
);
119 m
->buf
= kmalloc(m
->size
<<= 1, GFP_KERNEL
);
120 return !m
->buf
? -ENOMEM
: -EAGAIN
;
124 * seq_read - ->read() method for sequential files.
125 * @file: the file to read from
126 * @buf: the buffer to read to
127 * @size: the maximum number of bytes to read
128 * @ppos: the current position in the file
130 * Ready-made ->f_op->read()
132 ssize_t
seq_read(struct file
*file
, char __user
*buf
, size_t size
, loff_t
*ppos
)
134 struct seq_file
*m
= (struct seq_file
*)file
->private_data
;
141 mutex_lock(&m
->lock
);
143 /* Don't assume *ppos is where we left it */
144 if (unlikely(*ppos
!= m
->read_pos
)) {
146 while ((err
= traverse(m
, *ppos
)) == -EAGAIN
)
149 /* With prejudice... */
159 * seq_file->op->..m_start/m_stop/m_next may do special actions
160 * or optimisations based on the file->f_version, so we want to
161 * pass the file->f_version to those methods.
163 * seq_file->version is just copy of f_version, and seq_file
164 * methods can treat it simply as file version.
165 * It is copied in first and copied out after all operations.
166 * It is convenient to have it as part of structure to avoid the
167 * need of passing another argument to all the seq_file methods.
169 m
->version
= file
->f_version
;
170 /* grab buffer if we didn't have one */
172 m
->buf
= kmalloc(m
->size
= PAGE_SIZE
, GFP_KERNEL
);
176 /* if not empty - flush it first */
178 n
= min(m
->count
, size
);
179 err
= copy_to_user(buf
, m
->buf
+ m
->from
, n
);
192 /* we need at least one record in buffer */
194 p
= m
->op
->start(m
, &pos
);
199 err
= m
->op
->show(m
, p
);
204 if (unlikely(!m
->count
)) {
205 p
= m
->op
->next(m
, p
, &pos
);
209 if (m
->count
< m
->size
)
213 m
->buf
= kmalloc(m
->size
<<= 1, GFP_KERNEL
);
219 p
= m
->op
->start(m
, &pos
);
225 /* they want more? let's try to get some more */
226 while (m
->count
< size
) {
227 size_t offs
= m
->count
;
229 p
= m
->op
->next(m
, p
, &next
);
230 if (!p
|| IS_ERR(p
)) {
234 err
= m
->op
->show(m
, p
);
235 if (m
->count
== m
->size
|| err
) {
237 if (likely(err
<= 0))
243 n
= min(m
->count
, size
);
244 err
= copy_to_user(buf
, m
->buf
, n
);
259 m
->read_pos
+= copied
;
261 file
->f_version
= m
->version
;
262 mutex_unlock(&m
->lock
);
271 EXPORT_SYMBOL(seq_read
);
274 * seq_lseek - ->llseek() method for sequential files.
275 * @file: the file in question
276 * @offset: new position
277 * @origin: 0 for absolute, 1 for relative position
279 * Ready-made ->f_op->llseek()
281 loff_t
seq_lseek(struct file
*file
, loff_t offset
, int origin
)
283 struct seq_file
*m
= (struct seq_file
*)file
->private_data
;
284 loff_t retval
= -EINVAL
;
286 mutex_lock(&m
->lock
);
287 m
->version
= file
->f_version
;
290 offset
+= file
->f_pos
;
295 if (offset
!= m
->read_pos
) {
296 while ((retval
=traverse(m
, offset
)) == -EAGAIN
)
299 /* with extreme prejudice... */
306 m
->read_pos
= offset
;
307 retval
= file
->f_pos
= offset
;
311 file
->f_version
= m
->version
;
312 mutex_unlock(&m
->lock
);
315 EXPORT_SYMBOL(seq_lseek
);
318 * seq_release - free the structures associated with sequential file.
319 * @file: file in question
320 * @inode: file->f_path.dentry->d_inode
322 * Frees the structures associated with sequential file; can be used
323 * as ->f_op->release() if you don't have private data to destroy.
325 int seq_release(struct inode
*inode
, struct file
*file
)
327 struct seq_file
*m
= (struct seq_file
*)file
->private_data
;
329 if (m
->seq_ops_allocated
) {
330 struct dentry
*dentry
= file
->f_dentry
;
331 printk("memory leak: '%.*s'\n",
332 dentry
->d_name
.len
, dentry
->d_name
.name
);
339 EXPORT_SYMBOL(seq_release
);
342 * seq_escape - print string into buffer, escaping some characters
345 * @esc: set of characters that need escaping
347 * Puts string into buffer, replacing each occurrence of character from
348 * @esc with usual octal escape. Returns 0 in case of success, -1 - in
351 int seq_escape(struct seq_file
*m
, const char *s
, const char *esc
)
353 char *end
= m
->buf
+ m
->size
;
357 for (p
= m
->buf
+ m
->count
; (c
= *s
) != '\0' && p
< end
; s
++) {
358 if (!strchr(esc
, c
)) {
364 *p
++ = '0' + ((c
& 0300) >> 6);
365 *p
++ = '0' + ((c
& 070) >> 3);
366 *p
++ = '0' + (c
& 07);
372 m
->count
= p
- m
->buf
;
375 EXPORT_SYMBOL(seq_escape
);
377 int seq_printf(struct seq_file
*m
, const char *f
, ...)
382 if (m
->count
< m
->size
) {
384 len
= vsnprintf(m
->buf
+ m
->count
, m
->size
- m
->count
, f
, args
);
386 if (m
->count
+ len
< m
->size
) {
394 EXPORT_SYMBOL(seq_printf
);
397 * mangle_path - mangle and copy path to buffer beginning
399 * @p: beginning of path in above buffer
400 * @esc: set of characters that need escaping
402 * Copy the path from @p to @s, replacing each occurrence of character from
403 * @esc with usual octal escape.
404 * Returns pointer past last written character in @s, or NULL in case of
407 char *mangle_path(char *s
, char *p
, char *esc
)
413 } else if (!strchr(esc
, c
)) {
415 } else if (s
+ 4 > p
) {
419 *s
++ = '0' + ((c
& 0300) >> 6);
420 *s
++ = '0' + ((c
& 070) >> 3);
421 *s
++ = '0' + (c
& 07);
426 EXPORT_SYMBOL(mangle_path
);
429 * seq_path - seq_file interface to print a pathname
430 * @m: the seq_file handle
431 * @path: the struct path to print
432 * @esc: set of characters to escape in the output
434 * return the absolute path of 'path', as represented by the
435 * dentry / mnt pair in the path parameter.
437 int seq_path(struct seq_file
*m
, struct path
*path
, char *esc
)
440 size_t size
= seq_get_buf(m
, &buf
);
444 char *p
= d_path(path
, buf
, size
);
446 char *end
= mangle_path(buf
, p
, esc
);
455 EXPORT_SYMBOL(seq_path
);
458 * Same as seq_path, but relative to supplied root.
460 * root may be changed, see __d_path().
462 int seq_path_root(struct seq_file
*m
, struct path
*path
, struct path
*root
,
466 size_t size
= seq_get_buf(m
, &buf
);
467 int res
= -ENAMETOOLONG
;
472 spin_lock(&dcache_lock
);
473 p
= __d_path(path
, root
, buf
, size
);
474 spin_unlock(&dcache_lock
);
477 char *end
= mangle_path(buf
, p
, esc
);
486 return res
< 0 ? res
: 0;
490 * returns the path of the 'dentry' from the root of its filesystem.
492 int seq_dentry(struct seq_file
*m
, struct dentry
*dentry
, char *esc
)
495 size_t size
= seq_get_buf(m
, &buf
);
499 char *p
= dentry_path(dentry
, buf
, size
);
501 char *end
= mangle_path(buf
, p
, esc
);
511 int seq_bitmap(struct seq_file
*m
, const unsigned long *bits
,
512 unsigned int nr_bits
)
514 if (m
->count
< m
->size
) {
515 int len
= bitmap_scnprintf(m
->buf
+ m
->count
,
516 m
->size
- m
->count
, bits
, nr_bits
);
517 if (m
->count
+ len
< m
->size
) {
525 EXPORT_SYMBOL(seq_bitmap
);
527 int seq_bitmap_list(struct seq_file
*m
, const unsigned long *bits
,
528 unsigned int nr_bits
)
530 if (m
->count
< m
->size
) {
531 int len
= bitmap_scnlistprintf(m
->buf
+ m
->count
,
532 m
->size
- m
->count
, bits
, nr_bits
);
533 if (m
->count
+ len
< m
->size
) {
541 EXPORT_SYMBOL(seq_bitmap_list
);
543 static void *single_start(struct seq_file
*p
, loff_t
*pos
)
545 return NULL
+ (*pos
== 0);
548 static void *single_next(struct seq_file
*p
, void *v
, loff_t
*pos
)
554 static void single_stop(struct seq_file
*p
, void *v
)
558 int single_open(struct file
*file
, int (*show
)(struct seq_file
*, void *),
561 struct seq_operations
*op
= kmalloc(sizeof(*op
), GFP_KERNEL
);
565 op
->start
= single_start
;
566 op
->next
= single_next
;
567 op
->stop
= single_stop
;
569 res
= seq_open(file
, op
);
571 struct seq_file
*seq
= file
->private_data
;
574 seq
->seq_ops_allocated
= 1;
580 EXPORT_SYMBOL(single_open
);
582 int single_release(struct inode
*inode
, struct file
*file
)
584 struct seq_file
*seq
= file
->private_data
;
585 const struct seq_operations
*op
= seq
->op
;
588 /* All roads lead to seq_release(), so... */
589 seq
->seq_ops_allocated
= 0;
590 res
= seq_release(inode
, file
);
594 EXPORT_SYMBOL(single_release
);
596 int seq_release_private(struct inode
*inode
, struct file
*file
)
598 struct seq_file
*seq
= file
->private_data
;
602 return seq_release(inode
, file
);
604 EXPORT_SYMBOL(seq_release_private
);
606 void *__seq_open_private(struct file
*f
, const struct seq_operations
*ops
,
611 struct seq_file
*seq
;
613 private = kzalloc(psize
, GFP_KERNEL
);
617 rc
= seq_open(f
, ops
);
621 seq
= f
->private_data
;
622 seq
->private = private;
630 EXPORT_SYMBOL(__seq_open_private
);
632 int seq_open_private(struct file
*filp
, const struct seq_operations
*ops
,
635 return __seq_open_private(filp
, ops
, psize
) ? 0 : -ENOMEM
;
637 EXPORT_SYMBOL(seq_open_private
);
639 int seq_putc(struct seq_file
*m
, char c
)
641 if (m
->count
< m
->size
) {
642 m
->buf
[m
->count
++] = c
;
647 EXPORT_SYMBOL(seq_putc
);
649 int seq_puts(struct seq_file
*m
, const char *s
)
652 if (m
->count
+ len
< m
->size
) {
653 memcpy(m
->buf
+ m
->count
, s
, len
);
660 EXPORT_SYMBOL(seq_puts
);
663 * seq_write - write arbitrary data to buffer
664 * @seq: seq_file identifying the buffer to which data should be written
665 * @data: data address
666 * @len: number of bytes
668 * Return 0 on success, non-zero otherwise.
670 int seq_write(struct seq_file
*seq
, const void *data
, size_t len
)
672 if (seq
->count
+ len
< seq
->size
) {
673 memcpy(seq
->buf
+ seq
->count
, data
, len
);
677 seq
->count
= seq
->size
;
680 EXPORT_SYMBOL(seq_write
);
682 struct list_head
*seq_list_start(struct list_head
*head
, loff_t pos
)
684 struct list_head
*lh
;
686 list_for_each(lh
, head
)
693 EXPORT_SYMBOL(seq_list_start
);
695 struct list_head
*seq_list_start_head(struct list_head
*head
, loff_t pos
)
700 return seq_list_start(head
, pos
- 1);
703 EXPORT_SYMBOL(seq_list_start_head
);
705 struct list_head
*seq_list_next(void *v
, struct list_head
*head
, loff_t
*ppos
)
707 struct list_head
*lh
;
709 lh
= ((struct list_head
*)v
)->next
;
711 return lh
== head
? NULL
: lh
;
714 EXPORT_SYMBOL(seq_list_next
);