]>
git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - fs/seq_file.c
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/slab.h>
12 #include <linux/cred.h>
14 #include <asm/uaccess.h>
19 * seq_files have a buffer which can may overflow. When this happens a larger
20 * buffer is reallocated and all the data will be printed again.
21 * The overflow state is true when m->count == m->size.
23 static bool seq_overflow(struct seq_file
*m
)
25 return m
->count
== m
->size
;
28 static void seq_set_overflow(struct seq_file
*m
)
34 * seq_open - initialize sequential file
35 * @file: file we initialize
36 * @op: method table describing the sequence
38 * seq_open() sets @file, associating it with a sequence described
39 * by @op. @op->start() sets the iterator up and returns the first
40 * element of sequence. @op->stop() shuts it down. @op->next()
41 * returns the next element of sequence. @op->show() prints element
42 * into the buffer. In case of error ->start() and ->next() return
43 * ERR_PTR(error). In the end of sequence they return %NULL. ->show()
44 * returns 0 in case of success and negative number in case of error.
45 * Returning SEQ_SKIP means "discard this element and move on".
47 int seq_open(struct file
*file
, const struct seq_operations
*op
)
49 struct seq_file
*p
= file
->private_data
;
52 p
= kmalloc(sizeof(*p
), GFP_KERNEL
);
55 file
->private_data
= p
;
57 memset(p
, 0, sizeof(*p
));
61 p
->user_ns
= file
->f_cred
->user_ns
;
65 * Wrappers around seq_open(e.g. swaps_open) need to be
66 * aware of this. If they set f_version themselves, they
67 * should call seq_open first and then set f_version.
72 * seq_files support lseek() and pread(). They do not implement
73 * write() at all, but we clear FMODE_PWRITE here for historical
76 * If a client of seq_files a) implements file.write() and b) wishes to
77 * support pwrite() then that client will need to implement its own
78 * file.open() which calls seq_open() and then sets FMODE_PWRITE.
80 file
->f_mode
&= ~FMODE_PWRITE
;
83 EXPORT_SYMBOL(seq_open
);
85 static int traverse(struct seq_file
*m
, loff_t offset
)
87 loff_t pos
= 0, index
;
93 m
->count
= m
->from
= 0;
99 m
->buf
= kmalloc(m
->size
= PAGE_SIZE
, GFP_KERNEL
);
103 p
= m
->op
->start(m
, &index
);
108 error
= m
->op
->show(m
, p
);
111 if (unlikely(error
)) {
117 if (pos
+ m
->count
> offset
) {
118 m
->from
= offset
- pos
;
130 p
= m
->op
->next(m
, p
, &index
);
139 m
->buf
= kmalloc(m
->size
<<= 1, GFP_KERNEL
);
140 return !m
->buf
? -ENOMEM
: -EAGAIN
;
144 * seq_read - ->read() method for sequential files.
145 * @file: the file to read from
146 * @buf: the buffer to read to
147 * @size: the maximum number of bytes to read
148 * @ppos: the current position in the file
150 * Ready-made ->f_op->read()
152 ssize_t
seq_read(struct file
*file
, char __user
*buf
, size_t size
, loff_t
*ppos
)
154 struct seq_file
*m
= file
->private_data
;
161 mutex_lock(&m
->lock
);
164 * seq_file->op->..m_start/m_stop/m_next may do special actions
165 * or optimisations based on the file->f_version, so we want to
166 * pass the file->f_version to those methods.
168 * seq_file->version is just copy of f_version, and seq_file
169 * methods can treat it simply as file version.
170 * It is copied in first and copied out after all operations.
171 * It is convenient to have it as part of structure to avoid the
172 * need of passing another argument to all the seq_file methods.
174 m
->version
= file
->f_version
;
176 /* Don't assume *ppos is where we left it */
177 if (unlikely(*ppos
!= m
->read_pos
)) {
178 while ((err
= traverse(m
, *ppos
)) == -EAGAIN
)
181 /* With prejudice... */
192 /* grab buffer if we didn't have one */
194 m
->buf
= kmalloc(m
->size
= PAGE_SIZE
, GFP_KERNEL
);
198 /* if not empty - flush it first */
200 n
= min(m
->count
, size
);
201 err
= copy_to_user(buf
, m
->buf
+ m
->from
, n
);
214 /* we need at least one record in buffer */
216 p
= m
->op
->start(m
, &pos
);
221 err
= m
->op
->show(m
, p
);
226 if (unlikely(!m
->count
)) {
227 p
= m
->op
->next(m
, p
, &pos
);
231 if (m
->count
< m
->size
)
235 m
->buf
= kmalloc(m
->size
<<= 1, GFP_KERNEL
);
241 p
= m
->op
->start(m
, &pos
);
247 /* they want more? let's try to get some more */
248 while (m
->count
< size
) {
249 size_t offs
= m
->count
;
251 p
= m
->op
->next(m
, p
, &next
);
252 if (!p
|| IS_ERR(p
)) {
256 err
= m
->op
->show(m
, p
);
257 if (seq_overflow(m
) || err
) {
259 if (likely(err
<= 0))
265 n
= min(m
->count
, size
);
266 err
= copy_to_user(buf
, m
->buf
, n
);
281 m
->read_pos
+= copied
;
283 file
->f_version
= m
->version
;
284 mutex_unlock(&m
->lock
);
293 EXPORT_SYMBOL(seq_read
);
296 * seq_lseek - ->llseek() method for sequential files.
297 * @file: the file in question
298 * @offset: new position
299 * @whence: 0 for absolute, 1 for relative position
301 * Ready-made ->f_op->llseek()
303 loff_t
seq_lseek(struct file
*file
, loff_t offset
, int whence
)
305 struct seq_file
*m
= file
->private_data
;
306 loff_t retval
= -EINVAL
;
308 mutex_lock(&m
->lock
);
309 m
->version
= file
->f_version
;
312 offset
+= file
->f_pos
;
317 if (offset
!= m
->read_pos
) {
318 while ((retval
= traverse(m
, offset
)) == -EAGAIN
)
321 /* with extreme prejudice... */
328 m
->read_pos
= offset
;
329 retval
= file
->f_pos
= offset
;
332 file
->f_pos
= offset
;
335 file
->f_version
= m
->version
;
336 mutex_unlock(&m
->lock
);
339 EXPORT_SYMBOL(seq_lseek
);
342 * seq_release - free the structures associated with sequential file.
343 * @file: file in question
346 * Frees the structures associated with sequential file; can be used
347 * as ->f_op->release() if you don't have private data to destroy.
349 int seq_release(struct inode
*inode
, struct file
*file
)
351 struct seq_file
*m
= file
->private_data
;
356 EXPORT_SYMBOL(seq_release
);
359 * seq_escape - print string into buffer, escaping some characters
362 * @esc: set of characters that need escaping
364 * Puts string into buffer, replacing each occurrence of character from
365 * @esc with usual octal escape. Returns 0 in case of success, -1 - in
368 int seq_escape(struct seq_file
*m
, const char *s
, const char *esc
)
370 char *end
= m
->buf
+ m
->size
;
374 for (p
= m
->buf
+ m
->count
; (c
= *s
) != '\0' && p
< end
; s
++) {
375 if (!strchr(esc
, c
)) {
381 *p
++ = '0' + ((c
& 0300) >> 6);
382 *p
++ = '0' + ((c
& 070) >> 3);
383 *p
++ = '0' + (c
& 07);
389 m
->count
= p
- m
->buf
;
392 EXPORT_SYMBOL(seq_escape
);
394 int seq_vprintf(struct seq_file
*m
, const char *f
, va_list args
)
398 if (m
->count
< m
->size
) {
399 len
= vsnprintf(m
->buf
+ m
->count
, m
->size
- m
->count
, f
, args
);
400 if (m
->count
+ len
< m
->size
) {
408 EXPORT_SYMBOL(seq_vprintf
);
410 int seq_printf(struct seq_file
*m
, const char *f
, ...)
416 ret
= seq_vprintf(m
, f
, args
);
421 EXPORT_SYMBOL(seq_printf
);
424 * mangle_path - mangle and copy path to buffer beginning
426 * @p: beginning of path in above buffer
427 * @esc: set of characters that need escaping
429 * Copy the path from @p to @s, replacing each occurrence of character from
430 * @esc with usual octal escape.
431 * Returns pointer past last written character in @s, or NULL in case of
434 char *mangle_path(char *s
, const char *p
, const char *esc
)
440 } else if (!strchr(esc
, c
)) {
442 } else if (s
+ 4 > p
) {
446 *s
++ = '0' + ((c
& 0300) >> 6);
447 *s
++ = '0' + ((c
& 070) >> 3);
448 *s
++ = '0' + (c
& 07);
453 EXPORT_SYMBOL(mangle_path
);
456 * seq_path - seq_file interface to print a pathname
457 * @m: the seq_file handle
458 * @path: the struct path to print
459 * @esc: set of characters to escape in the output
461 * return the absolute path of 'path', as represented by the
462 * dentry / mnt pair in the path parameter.
464 int seq_path(struct seq_file
*m
, const struct path
*path
, const char *esc
)
467 size_t size
= seq_get_buf(m
, &buf
);
471 char *p
= d_path(path
, buf
, size
);
473 char *end
= mangle_path(buf
, p
, esc
);
482 EXPORT_SYMBOL(seq_path
);
485 * Same as seq_path, but relative to supplied root.
487 int seq_path_root(struct seq_file
*m
, const struct path
*path
,
488 const struct path
*root
, const char *esc
)
491 size_t size
= seq_get_buf(m
, &buf
);
492 int res
= -ENAMETOOLONG
;
497 p
= __d_path(path
, root
, buf
, size
);
502 char *end
= mangle_path(buf
, p
, esc
);
511 return res
< 0 && res
!= -ENAMETOOLONG
? res
: 0;
515 * returns the path of the 'dentry' from the root of its filesystem.
517 int seq_dentry(struct seq_file
*m
, struct dentry
*dentry
, const char *esc
)
520 size_t size
= seq_get_buf(m
, &buf
);
524 char *p
= dentry_path(dentry
, buf
, size
);
526 char *end
= mangle_path(buf
, p
, esc
);
536 int seq_bitmap(struct seq_file
*m
, const unsigned long *bits
,
537 unsigned int nr_bits
)
539 if (m
->count
< m
->size
) {
540 int len
= bitmap_scnprintf(m
->buf
+ m
->count
,
541 m
->size
- m
->count
, bits
, nr_bits
);
542 if (m
->count
+ len
< m
->size
) {
550 EXPORT_SYMBOL(seq_bitmap
);
552 int seq_bitmap_list(struct seq_file
*m
, const unsigned long *bits
,
553 unsigned int nr_bits
)
555 if (m
->count
< m
->size
) {
556 int len
= bitmap_scnlistprintf(m
->buf
+ m
->count
,
557 m
->size
- m
->count
, bits
, nr_bits
);
558 if (m
->count
+ len
< m
->size
) {
566 EXPORT_SYMBOL(seq_bitmap_list
);
568 static void *single_start(struct seq_file
*p
, loff_t
*pos
)
570 return NULL
+ (*pos
== 0);
573 static void *single_next(struct seq_file
*p
, void *v
, loff_t
*pos
)
579 static void single_stop(struct seq_file
*p
, void *v
)
583 int single_open(struct file
*file
, int (*show
)(struct seq_file
*, void *),
586 struct seq_operations
*op
= kmalloc(sizeof(*op
), GFP_KERNEL
);
590 op
->start
= single_start
;
591 op
->next
= single_next
;
592 op
->stop
= single_stop
;
594 res
= seq_open(file
, op
);
596 ((struct seq_file
*)file
->private_data
)->private = data
;
602 EXPORT_SYMBOL(single_open
);
604 int single_open_size(struct file
*file
, int (*show
)(struct seq_file
*, void *),
605 void *data
, size_t size
)
607 char *buf
= kmalloc(size
, GFP_KERNEL
);
611 ret
= single_open(file
, show
, data
);
616 ((struct seq_file
*)file
->private_data
)->buf
= buf
;
617 ((struct seq_file
*)file
->private_data
)->size
= size
;
620 EXPORT_SYMBOL(single_open_size
);
622 int single_release(struct inode
*inode
, struct file
*file
)
624 const struct seq_operations
*op
= ((struct seq_file
*)file
->private_data
)->op
;
625 int res
= seq_release(inode
, file
);
629 EXPORT_SYMBOL(single_release
);
631 int seq_release_private(struct inode
*inode
, struct file
*file
)
633 struct seq_file
*seq
= file
->private_data
;
637 return seq_release(inode
, file
);
639 EXPORT_SYMBOL(seq_release_private
);
641 void *__seq_open_private(struct file
*f
, const struct seq_operations
*ops
,
646 struct seq_file
*seq
;
648 private = kzalloc(psize
, GFP_KERNEL
);
652 rc
= seq_open(f
, ops
);
656 seq
= f
->private_data
;
657 seq
->private = private;
665 EXPORT_SYMBOL(__seq_open_private
);
667 int seq_open_private(struct file
*filp
, const struct seq_operations
*ops
,
670 return __seq_open_private(filp
, ops
, psize
) ? 0 : -ENOMEM
;
672 EXPORT_SYMBOL(seq_open_private
);
674 int seq_putc(struct seq_file
*m
, char c
)
676 if (m
->count
< m
->size
) {
677 m
->buf
[m
->count
++] = c
;
682 EXPORT_SYMBOL(seq_putc
);
684 int seq_puts(struct seq_file
*m
, const char *s
)
687 if (m
->count
+ len
< m
->size
) {
688 memcpy(m
->buf
+ m
->count
, s
, len
);
695 EXPORT_SYMBOL(seq_puts
);
698 * A helper routine for putting decimal numbers without rich format of printf().
699 * only 'unsigned long long' is supported.
700 * This routine will put one byte delimiter + number into seq_file.
701 * This routine is very quick when you show lots of numbers.
702 * In usual cases, it will be better to use seq_printf(). It's easier to read.
704 int seq_put_decimal_ull(struct seq_file
*m
, char delimiter
,
705 unsigned long long num
)
709 if (m
->count
+ 2 >= m
->size
) /* we'll write 2 bytes at least */
713 m
->buf
[m
->count
++] = delimiter
;
716 m
->buf
[m
->count
++] = num
+ '0';
720 len
= num_to_str(m
->buf
+ m
->count
, m
->size
- m
->count
, num
);
729 EXPORT_SYMBOL(seq_put_decimal_ull
);
731 int seq_put_decimal_ll(struct seq_file
*m
, char delimiter
,
735 if (m
->count
+ 3 >= m
->size
) {
740 m
->buf
[m
->count
++] = delimiter
;
744 return seq_put_decimal_ull(m
, delimiter
, num
);
747 EXPORT_SYMBOL(seq_put_decimal_ll
);
750 * seq_write - write arbitrary data to buffer
751 * @seq: seq_file identifying the buffer to which data should be written
752 * @data: data address
753 * @len: number of bytes
755 * Return 0 on success, non-zero otherwise.
757 int seq_write(struct seq_file
*seq
, const void *data
, size_t len
)
759 if (seq
->count
+ len
< seq
->size
) {
760 memcpy(seq
->buf
+ seq
->count
, data
, len
);
764 seq_set_overflow(seq
);
767 EXPORT_SYMBOL(seq_write
);
770 * seq_pad - write padding spaces to buffer
771 * @m: seq_file identifying the buffer to which data should be written
772 * @c: the byte to append after padding if non-zero
774 void seq_pad(struct seq_file
*m
, char c
)
776 int size
= m
->pad_until
- m
->count
;
778 seq_printf(m
, "%*s", size
, "");
782 EXPORT_SYMBOL(seq_pad
);
784 struct list_head
*seq_list_start(struct list_head
*head
, loff_t pos
)
786 struct list_head
*lh
;
788 list_for_each(lh
, head
)
794 EXPORT_SYMBOL(seq_list_start
);
796 struct list_head
*seq_list_start_head(struct list_head
*head
, loff_t pos
)
801 return seq_list_start(head
, pos
- 1);
803 EXPORT_SYMBOL(seq_list_start_head
);
805 struct list_head
*seq_list_next(void *v
, struct list_head
*head
, loff_t
*ppos
)
807 struct list_head
*lh
;
809 lh
= ((struct list_head
*)v
)->next
;
811 return lh
== head
? NULL
: lh
;
813 EXPORT_SYMBOL(seq_list_next
);
816 * seq_hlist_start - start an iteration of a hlist
817 * @head: the head of the hlist
818 * @pos: the start position of the sequence
820 * Called at seq_file->op->start().
822 struct hlist_node
*seq_hlist_start(struct hlist_head
*head
, loff_t pos
)
824 struct hlist_node
*node
;
826 hlist_for_each(node
, head
)
831 EXPORT_SYMBOL(seq_hlist_start
);
834 * seq_hlist_start_head - start an iteration of a hlist
835 * @head: the head of the hlist
836 * @pos: the start position of the sequence
838 * Called at seq_file->op->start(). Call this function if you want to
839 * print a header at the top of the output.
841 struct hlist_node
*seq_hlist_start_head(struct hlist_head
*head
, loff_t pos
)
844 return SEQ_START_TOKEN
;
846 return seq_hlist_start(head
, pos
- 1);
848 EXPORT_SYMBOL(seq_hlist_start_head
);
851 * seq_hlist_next - move to the next position of the hlist
852 * @v: the current iterator
853 * @head: the head of the hlist
854 * @ppos: the current position
856 * Called at seq_file->op->next().
858 struct hlist_node
*seq_hlist_next(void *v
, struct hlist_head
*head
,
861 struct hlist_node
*node
= v
;
864 if (v
== SEQ_START_TOKEN
)
869 EXPORT_SYMBOL(seq_hlist_next
);
872 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
873 * @head: the head of the hlist
874 * @pos: the start position of the sequence
876 * Called at seq_file->op->start().
878 * This list-traversal primitive may safely run concurrently with
879 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
880 * as long as the traversal is guarded by rcu_read_lock().
882 struct hlist_node
*seq_hlist_start_rcu(struct hlist_head
*head
,
885 struct hlist_node
*node
;
887 __hlist_for_each_rcu(node
, head
)
892 EXPORT_SYMBOL(seq_hlist_start_rcu
);
895 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
896 * @head: the head of the hlist
897 * @pos: the start position of the sequence
899 * Called at seq_file->op->start(). Call this function if you want to
900 * print a header at the top of the output.
902 * This list-traversal primitive may safely run concurrently with
903 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
904 * as long as the traversal is guarded by rcu_read_lock().
906 struct hlist_node
*seq_hlist_start_head_rcu(struct hlist_head
*head
,
910 return SEQ_START_TOKEN
;
912 return seq_hlist_start_rcu(head
, pos
- 1);
914 EXPORT_SYMBOL(seq_hlist_start_head_rcu
);
917 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
918 * @v: the current iterator
919 * @head: the head of the hlist
920 * @ppos: the current position
922 * Called at seq_file->op->next().
924 * This list-traversal primitive may safely run concurrently with
925 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
926 * as long as the traversal is guarded by rcu_read_lock().
928 struct hlist_node
*seq_hlist_next_rcu(void *v
,
929 struct hlist_head
*head
,
932 struct hlist_node
*node
= v
;
935 if (v
== SEQ_START_TOKEN
)
936 return rcu_dereference(head
->first
);
938 return rcu_dereference(node
->next
);
940 EXPORT_SYMBOL(seq_hlist_next_rcu
);
943 * seq_hlist_start_precpu - start an iteration of a percpu hlist array
944 * @head: pointer to percpu array of struct hlist_heads
945 * @cpu: pointer to cpu "cursor"
946 * @pos: start position of sequence
948 * Called at seq_file->op->start().
951 seq_hlist_start_percpu(struct hlist_head __percpu
*head
, int *cpu
, loff_t pos
)
953 struct hlist_node
*node
;
955 for_each_possible_cpu(*cpu
) {
956 hlist_for_each(node
, per_cpu_ptr(head
, *cpu
)) {
963 EXPORT_SYMBOL(seq_hlist_start_percpu
);
966 * seq_hlist_next_percpu - move to the next position of the percpu hlist array
967 * @v: pointer to current hlist_node
968 * @head: pointer to percpu array of struct hlist_heads
969 * @cpu: pointer to cpu "cursor"
970 * @pos: start position of sequence
972 * Called at seq_file->op->next().
975 seq_hlist_next_percpu(void *v
, struct hlist_head __percpu
*head
,
976 int *cpu
, loff_t
*pos
)
978 struct hlist_node
*node
= v
;
985 for (*cpu
= cpumask_next(*cpu
, cpu_possible_mask
); *cpu
< nr_cpu_ids
;
986 *cpu
= cpumask_next(*cpu
, cpu_possible_mask
)) {
987 struct hlist_head
*bucket
= per_cpu_ptr(head
, *cpu
);
989 if (!hlist_empty(bucket
))
990 return bucket
->first
;
994 EXPORT_SYMBOL(seq_hlist_next_percpu
);