4 * helper functions for making synthetic files from sequences of records.
5 * initial implementation -- AV, Oct 2001.
9 #include <linux/export.h>
10 #include <linux/seq_file.h>
11 #include <linux/vmalloc.h>
12 #include <linux/slab.h>
13 #include <linux/cred.h>
16 #include <asm/uaccess.h>
19 static void seq_set_overflow(struct seq_file
*m
)
24 static void *seq_buf_alloc(unsigned long size
)
29 * __GFP_NORETRY to avoid oom-killings with high-order allocations -
30 * it's better to fall back to vmalloc() than to kill things.
32 buf
= kmalloc(size
, GFP_KERNEL
| __GFP_NORETRY
| __GFP_NOWARN
);
33 if (!buf
&& size
> PAGE_SIZE
)
39 * seq_open - initialize sequential file
40 * @file: file we initialize
41 * @op: method table describing the sequence
43 * seq_open() sets @file, associating it with a sequence described
44 * by @op. @op->start() sets the iterator up and returns the first
45 * element of sequence. @op->stop() shuts it down. @op->next()
46 * returns the next element of sequence. @op->show() prints element
47 * into the buffer. In case of error ->start() and ->next() return
48 * ERR_PTR(error). In the end of sequence they return %NULL. ->show()
49 * returns 0 in case of success and negative number in case of error.
50 * Returning SEQ_SKIP means "discard this element and move on".
52 int seq_open(struct file
*file
, const struct seq_operations
*op
)
54 struct seq_file
*p
= file
->private_data
;
57 p
= kmalloc(sizeof(*p
), GFP_KERNEL
);
60 file
->private_data
= p
;
62 memset(p
, 0, sizeof(*p
));
66 p
->user_ns
= file
->f_cred
->user_ns
;
70 * Wrappers around seq_open(e.g. swaps_open) need to be
71 * aware of this. If they set f_version themselves, they
72 * should call seq_open first and then set f_version.
77 * seq_files support lseek() and pread(). They do not implement
78 * write() at all, but we clear FMODE_PWRITE here for historical
81 * If a client of seq_files a) implements file.write() and b) wishes to
82 * support pwrite() then that client will need to implement its own
83 * file.open() which calls seq_open() and then sets FMODE_PWRITE.
85 file
->f_mode
&= ~FMODE_PWRITE
;
88 EXPORT_SYMBOL(seq_open
);
90 static int traverse(struct seq_file
*m
, loff_t offset
)
92 loff_t pos
= 0, index
;
98 m
->count
= m
->from
= 0;
104 m
->buf
= seq_buf_alloc(m
->size
= PAGE_SIZE
);
108 p
= m
->op
->start(m
, &index
);
113 error
= m
->op
->show(m
, p
);
116 if (unlikely(error
)) {
120 if (seq_has_overflowed(m
))
122 if (pos
+ m
->count
> offset
) {
123 m
->from
= offset
- pos
;
135 p
= m
->op
->next(m
, p
, &index
);
145 m
->buf
= seq_buf_alloc(m
->size
<<= 1);
146 return !m
->buf
? -ENOMEM
: -EAGAIN
;
150 * seq_read - ->read() method for sequential files.
151 * @file: the file to read from
152 * @buf: the buffer to read to
153 * @size: the maximum number of bytes to read
154 * @ppos: the current position in the file
156 * Ready-made ->f_op->read()
158 ssize_t
seq_read(struct file
*file
, char __user
*buf
, size_t size
, loff_t
*ppos
)
160 struct seq_file
*m
= file
->private_data
;
167 mutex_lock(&m
->lock
);
170 * seq_file->op->..m_start/m_stop/m_next may do special actions
171 * or optimisations based on the file->f_version, so we want to
172 * pass the file->f_version to those methods.
174 * seq_file->version is just copy of f_version, and seq_file
175 * methods can treat it simply as file version.
176 * It is copied in first and copied out after all operations.
177 * It is convenient to have it as part of structure to avoid the
178 * need of passing another argument to all the seq_file methods.
180 m
->version
= file
->f_version
;
182 /* Don't assume *ppos is where we left it */
183 if (unlikely(*ppos
!= m
->read_pos
)) {
184 while ((err
= traverse(m
, *ppos
)) == -EAGAIN
)
187 /* With prejudice... */
198 /* grab buffer if we didn't have one */
200 m
->buf
= seq_buf_alloc(m
->size
= PAGE_SIZE
);
204 /* if not empty - flush it first */
206 n
= min(m
->count
, size
);
207 err
= copy_to_user(buf
, m
->buf
+ m
->from
, n
);
220 /* we need at least one record in buffer */
222 p
= m
->op
->start(m
, &pos
);
227 err
= m
->op
->show(m
, p
);
232 if (unlikely(!m
->count
)) {
233 p
= m
->op
->next(m
, p
, &pos
);
237 if (m
->count
< m
->size
)
242 m
->buf
= seq_buf_alloc(m
->size
<<= 1);
247 p
= m
->op
->start(m
, &pos
);
253 /* they want more? let's try to get some more */
254 while (m
->count
< size
) {
255 size_t offs
= m
->count
;
257 p
= m
->op
->next(m
, p
, &next
);
258 if (!p
|| IS_ERR(p
)) {
262 err
= m
->op
->show(m
, p
);
263 if (seq_has_overflowed(m
) || err
) {
265 if (likely(err
<= 0))
271 n
= min(m
->count
, size
);
272 err
= copy_to_user(buf
, m
->buf
, n
);
287 m
->read_pos
+= copied
;
289 file
->f_version
= m
->version
;
290 mutex_unlock(&m
->lock
);
299 EXPORT_SYMBOL(seq_read
);
302 * seq_lseek - ->llseek() method for sequential files.
303 * @file: the file in question
304 * @offset: new position
305 * @whence: 0 for absolute, 1 for relative position
307 * Ready-made ->f_op->llseek()
309 loff_t
seq_lseek(struct file
*file
, loff_t offset
, int whence
)
311 struct seq_file
*m
= file
->private_data
;
312 loff_t retval
= -EINVAL
;
314 mutex_lock(&m
->lock
);
315 m
->version
= file
->f_version
;
318 offset
+= file
->f_pos
;
323 if (offset
!= m
->read_pos
) {
324 while ((retval
= traverse(m
, offset
)) == -EAGAIN
)
327 /* with extreme prejudice... */
334 m
->read_pos
= offset
;
335 retval
= file
->f_pos
= offset
;
338 file
->f_pos
= offset
;
341 file
->f_version
= m
->version
;
342 mutex_unlock(&m
->lock
);
345 EXPORT_SYMBOL(seq_lseek
);
348 * seq_release - free the structures associated with sequential file.
349 * @file: file in question
352 * Frees the structures associated with sequential file; can be used
353 * as ->f_op->release() if you don't have private data to destroy.
355 int seq_release(struct inode
*inode
, struct file
*file
)
357 struct seq_file
*m
= file
->private_data
;
362 EXPORT_SYMBOL(seq_release
);
365 * seq_escape - print string into buffer, escaping some characters
368 * @esc: set of characters that need escaping
370 * Puts string into buffer, replacing each occurrence of character from
371 * @esc with usual octal escape. Returns 0 in case of success, -1 - in
374 int seq_escape(struct seq_file
*m
, const char *s
, const char *esc
)
376 char *end
= m
->buf
+ m
->size
;
380 for (p
= m
->buf
+ m
->count
; (c
= *s
) != '\0' && p
< end
; s
++) {
381 if (!strchr(esc
, c
)) {
387 *p
++ = '0' + ((c
& 0300) >> 6);
388 *p
++ = '0' + ((c
& 070) >> 3);
389 *p
++ = '0' + (c
& 07);
395 m
->count
= p
- m
->buf
;
398 EXPORT_SYMBOL(seq_escape
);
400 int seq_vprintf(struct seq_file
*m
, const char *f
, va_list args
)
404 if (m
->count
< m
->size
) {
405 len
= vsnprintf(m
->buf
+ m
->count
, m
->size
- m
->count
, f
, args
);
406 if (m
->count
+ len
< m
->size
) {
414 EXPORT_SYMBOL(seq_vprintf
);
416 int seq_printf(struct seq_file
*m
, const char *f
, ...)
422 ret
= seq_vprintf(m
, f
, args
);
427 EXPORT_SYMBOL(seq_printf
);
430 * mangle_path - mangle and copy path to buffer beginning
432 * @p: beginning of path in above buffer
433 * @esc: set of characters that need escaping
435 * Copy the path from @p to @s, replacing each occurrence of character from
436 * @esc with usual octal escape.
437 * Returns pointer past last written character in @s, or NULL in case of
440 char *mangle_path(char *s
, const char *p
, const char *esc
)
446 } else if (!strchr(esc
, c
)) {
448 } else if (s
+ 4 > p
) {
452 *s
++ = '0' + ((c
& 0300) >> 6);
453 *s
++ = '0' + ((c
& 070) >> 3);
454 *s
++ = '0' + (c
& 07);
459 EXPORT_SYMBOL(mangle_path
);
462 * seq_path - seq_file interface to print a pathname
463 * @m: the seq_file handle
464 * @path: the struct path to print
465 * @esc: set of characters to escape in the output
467 * return the absolute path of 'path', as represented by the
468 * dentry / mnt pair in the path parameter.
470 int seq_path(struct seq_file
*m
, const struct path
*path
, const char *esc
)
473 size_t size
= seq_get_buf(m
, &buf
);
477 char *p
= d_path(path
, buf
, size
);
479 char *end
= mangle_path(buf
, p
, esc
);
488 EXPORT_SYMBOL(seq_path
);
491 * Same as seq_path, but relative to supplied root.
493 int seq_path_root(struct seq_file
*m
, const struct path
*path
,
494 const struct path
*root
, const char *esc
)
497 size_t size
= seq_get_buf(m
, &buf
);
498 int res
= -ENAMETOOLONG
;
503 p
= __d_path(path
, root
, buf
, size
);
508 char *end
= mangle_path(buf
, p
, esc
);
517 return res
< 0 && res
!= -ENAMETOOLONG
? res
: 0;
521 * returns the path of the 'dentry' from the root of its filesystem.
523 int seq_dentry(struct seq_file
*m
, struct dentry
*dentry
, const char *esc
)
526 size_t size
= seq_get_buf(m
, &buf
);
530 char *p
= dentry_path(dentry
, buf
, size
);
532 char *end
= mangle_path(buf
, p
, esc
);
541 EXPORT_SYMBOL(seq_dentry
);
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
*)file
->private_data
)->private = data
;
577 EXPORT_SYMBOL(single_open
);
579 int single_open_size(struct file
*file
, int (*show
)(struct seq_file
*, void *),
580 void *data
, size_t size
)
582 char *buf
= seq_buf_alloc(size
);
586 ret
= single_open(file
, show
, data
);
591 ((struct seq_file
*)file
->private_data
)->buf
= buf
;
592 ((struct seq_file
*)file
->private_data
)->size
= size
;
595 EXPORT_SYMBOL(single_open_size
);
597 int single_release(struct inode
*inode
, struct file
*file
)
599 const struct seq_operations
*op
= ((struct seq_file
*)file
->private_data
)->op
;
600 int res
= seq_release(inode
, file
);
604 EXPORT_SYMBOL(single_release
);
606 int seq_release_private(struct inode
*inode
, struct file
*file
)
608 struct seq_file
*seq
= file
->private_data
;
612 return seq_release(inode
, file
);
614 EXPORT_SYMBOL(seq_release_private
);
616 void *__seq_open_private(struct file
*f
, const struct seq_operations
*ops
,
621 struct seq_file
*seq
;
623 private = kzalloc(psize
, GFP_KERNEL
);
627 rc
= seq_open(f
, ops
);
631 seq
= f
->private_data
;
632 seq
->private = private;
640 EXPORT_SYMBOL(__seq_open_private
);
642 int seq_open_private(struct file
*filp
, const struct seq_operations
*ops
,
645 return __seq_open_private(filp
, ops
, psize
) ? 0 : -ENOMEM
;
647 EXPORT_SYMBOL(seq_open_private
);
649 int seq_putc(struct seq_file
*m
, char c
)
651 if (m
->count
< m
->size
) {
652 m
->buf
[m
->count
++] = c
;
657 EXPORT_SYMBOL(seq_putc
);
659 int seq_puts(struct seq_file
*m
, const char *s
)
662 if (m
->count
+ len
< m
->size
) {
663 memcpy(m
->buf
+ m
->count
, s
, len
);
670 EXPORT_SYMBOL(seq_puts
);
673 * A helper routine for putting decimal numbers without rich format of printf().
674 * only 'unsigned long long' is supported.
675 * This routine will put one byte delimiter + number into seq_file.
676 * This routine is very quick when you show lots of numbers.
677 * In usual cases, it will be better to use seq_printf(). It's easier to read.
679 int seq_put_decimal_ull(struct seq_file
*m
, char delimiter
,
680 unsigned long long num
)
684 if (m
->count
+ 2 >= m
->size
) /* we'll write 2 bytes at least */
688 m
->buf
[m
->count
++] = delimiter
;
691 m
->buf
[m
->count
++] = num
+ '0';
695 len
= num_to_str(m
->buf
+ m
->count
, m
->size
- m
->count
, num
);
704 EXPORT_SYMBOL(seq_put_decimal_ull
);
706 int seq_put_decimal_ll(struct seq_file
*m
, char delimiter
,
710 if (m
->count
+ 3 >= m
->size
) {
715 m
->buf
[m
->count
++] = delimiter
;
719 return seq_put_decimal_ull(m
, delimiter
, num
);
722 EXPORT_SYMBOL(seq_put_decimal_ll
);
725 * seq_write - write arbitrary data to buffer
726 * @seq: seq_file identifying the buffer to which data should be written
727 * @data: data address
728 * @len: number of bytes
730 * Return 0 on success, non-zero otherwise.
732 int seq_write(struct seq_file
*seq
, const void *data
, size_t len
)
734 if (seq
->count
+ len
< seq
->size
) {
735 memcpy(seq
->buf
+ seq
->count
, data
, len
);
739 seq_set_overflow(seq
);
742 EXPORT_SYMBOL(seq_write
);
745 * seq_pad - write padding spaces to buffer
746 * @m: seq_file identifying the buffer to which data should be written
747 * @c: the byte to append after padding if non-zero
749 void seq_pad(struct seq_file
*m
, char c
)
751 int size
= m
->pad_until
- m
->count
;
753 seq_printf(m
, "%*s", size
, "");
757 EXPORT_SYMBOL(seq_pad
);
759 struct list_head
*seq_list_start(struct list_head
*head
, loff_t pos
)
761 struct list_head
*lh
;
763 list_for_each(lh
, head
)
769 EXPORT_SYMBOL(seq_list_start
);
771 struct list_head
*seq_list_start_head(struct list_head
*head
, loff_t pos
)
776 return seq_list_start(head
, pos
- 1);
778 EXPORT_SYMBOL(seq_list_start_head
);
780 struct list_head
*seq_list_next(void *v
, struct list_head
*head
, loff_t
*ppos
)
782 struct list_head
*lh
;
784 lh
= ((struct list_head
*)v
)->next
;
786 return lh
== head
? NULL
: lh
;
788 EXPORT_SYMBOL(seq_list_next
);
791 * seq_hlist_start - start an iteration of a hlist
792 * @head: the head of the hlist
793 * @pos: the start position of the sequence
795 * Called at seq_file->op->start().
797 struct hlist_node
*seq_hlist_start(struct hlist_head
*head
, loff_t pos
)
799 struct hlist_node
*node
;
801 hlist_for_each(node
, head
)
806 EXPORT_SYMBOL(seq_hlist_start
);
809 * seq_hlist_start_head - start an iteration of a hlist
810 * @head: the head of the hlist
811 * @pos: the start position of the sequence
813 * Called at seq_file->op->start(). Call this function if you want to
814 * print a header at the top of the output.
816 struct hlist_node
*seq_hlist_start_head(struct hlist_head
*head
, loff_t pos
)
819 return SEQ_START_TOKEN
;
821 return seq_hlist_start(head
, pos
- 1);
823 EXPORT_SYMBOL(seq_hlist_start_head
);
826 * seq_hlist_next - move to the next position of the hlist
827 * @v: the current iterator
828 * @head: the head of the hlist
829 * @ppos: the current position
831 * Called at seq_file->op->next().
833 struct hlist_node
*seq_hlist_next(void *v
, struct hlist_head
*head
,
836 struct hlist_node
*node
= v
;
839 if (v
== SEQ_START_TOKEN
)
844 EXPORT_SYMBOL(seq_hlist_next
);
847 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
848 * @head: the head of the hlist
849 * @pos: the start position of the sequence
851 * Called at seq_file->op->start().
853 * This list-traversal primitive may safely run concurrently with
854 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
855 * as long as the traversal is guarded by rcu_read_lock().
857 struct hlist_node
*seq_hlist_start_rcu(struct hlist_head
*head
,
860 struct hlist_node
*node
;
862 __hlist_for_each_rcu(node
, head
)
867 EXPORT_SYMBOL(seq_hlist_start_rcu
);
870 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
871 * @head: the head of the hlist
872 * @pos: the start position of the sequence
874 * Called at seq_file->op->start(). Call this function if you want to
875 * print a header at the top of the output.
877 * This list-traversal primitive may safely run concurrently with
878 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
879 * as long as the traversal is guarded by rcu_read_lock().
881 struct hlist_node
*seq_hlist_start_head_rcu(struct hlist_head
*head
,
885 return SEQ_START_TOKEN
;
887 return seq_hlist_start_rcu(head
, pos
- 1);
889 EXPORT_SYMBOL(seq_hlist_start_head_rcu
);
892 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
893 * @v: the current iterator
894 * @head: the head of the hlist
895 * @ppos: the current position
897 * Called at seq_file->op->next().
899 * This list-traversal primitive may safely run concurrently with
900 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
901 * as long as the traversal is guarded by rcu_read_lock().
903 struct hlist_node
*seq_hlist_next_rcu(void *v
,
904 struct hlist_head
*head
,
907 struct hlist_node
*node
= v
;
910 if (v
== SEQ_START_TOKEN
)
911 return rcu_dereference(head
->first
);
913 return rcu_dereference(node
->next
);
915 EXPORT_SYMBOL(seq_hlist_next_rcu
);
918 * seq_hlist_start_precpu - start an iteration of a percpu hlist array
919 * @head: pointer to percpu array of struct hlist_heads
920 * @cpu: pointer to cpu "cursor"
921 * @pos: start position of sequence
923 * Called at seq_file->op->start().
926 seq_hlist_start_percpu(struct hlist_head __percpu
*head
, int *cpu
, loff_t pos
)
928 struct hlist_node
*node
;
930 for_each_possible_cpu(*cpu
) {
931 hlist_for_each(node
, per_cpu_ptr(head
, *cpu
)) {
938 EXPORT_SYMBOL(seq_hlist_start_percpu
);
941 * seq_hlist_next_percpu - move to the next position of the percpu hlist array
942 * @v: pointer to current hlist_node
943 * @head: pointer to percpu array of struct hlist_heads
944 * @cpu: pointer to cpu "cursor"
945 * @pos: start position of sequence
947 * Called at seq_file->op->next().
950 seq_hlist_next_percpu(void *v
, struct hlist_head __percpu
*head
,
951 int *cpu
, loff_t
*pos
)
953 struct hlist_node
*node
= v
;
960 for (*cpu
= cpumask_next(*cpu
, cpu_possible_mask
); *cpu
< nr_cpu_ids
;
961 *cpu
= cpumask_next(*cpu
, cpu_possible_mask
)) {
962 struct hlist_head
*bucket
= per_cpu_ptr(head
, *cpu
);
964 if (!hlist_empty(bucket
))
965 return bucket
->first
;
969 EXPORT_SYMBOL(seq_hlist_next_percpu
);
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