]>
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/vmalloc.h>
12 #include <linux/slab.h>
13 #include <linux/cred.h>
15 #include <linux/printk.h>
17 #include <asm/uaccess.h>
20 static void seq_set_overflow(struct seq_file
*m
)
25 static void *seq_buf_alloc(unsigned long size
)
30 * __GFP_NORETRY to avoid oom-killings with high-order allocations -
31 * it's better to fall back to vmalloc() than to kill things.
33 buf
= kmalloc(size
, GFP_KERNEL
| __GFP_NORETRY
| __GFP_NOWARN
);
34 if (!buf
&& size
> PAGE_SIZE
)
40 * seq_open - initialize sequential file
41 * @file: file we initialize
42 * @op: method table describing the sequence
44 * seq_open() sets @file, associating it with a sequence described
45 * by @op. @op->start() sets the iterator up and returns the first
46 * element of sequence. @op->stop() shuts it down. @op->next()
47 * returns the next element of sequence. @op->show() prints element
48 * into the buffer. In case of error ->start() and ->next() return
49 * ERR_PTR(error). In the end of sequence they return %NULL. ->show()
50 * returns 0 in case of success and negative number in case of error.
51 * Returning SEQ_SKIP means "discard this element and move on".
52 * Note: seq_open() will allocate a struct seq_file and store its
53 * pointer in @file->private_data. This pointer should not be modified.
55 int seq_open(struct file
*file
, const struct seq_operations
*op
)
59 WARN_ON(file
->private_data
);
61 p
= kzalloc(sizeof(*p
), GFP_KERNEL
);
65 file
->private_data
= p
;
70 p
->user_ns
= file
->f_cred
->user_ns
;
74 * Wrappers around seq_open(e.g. swaps_open) need to be
75 * aware of this. If they set f_version themselves, they
76 * should call seq_open first and then set f_version.
81 * seq_files support lseek() and pread(). They do not implement
82 * write() at all, but we clear FMODE_PWRITE here for historical
85 * If a client of seq_files a) implements file.write() and b) wishes to
86 * support pwrite() then that client will need to implement its own
87 * file.open() which calls seq_open() and then sets FMODE_PWRITE.
89 file
->f_mode
&= ~FMODE_PWRITE
;
92 EXPORT_SYMBOL(seq_open
);
94 static int traverse(struct seq_file
*m
, loff_t offset
)
96 loff_t pos
= 0, index
;
102 m
->count
= m
->from
= 0;
108 m
->buf
= seq_buf_alloc(m
->size
= PAGE_SIZE
);
112 p
= m
->op
->start(m
, &index
);
117 error
= m
->op
->show(m
, p
);
120 if (unlikely(error
)) {
124 if (seq_has_overflowed(m
))
126 if (pos
+ m
->count
> offset
) {
127 m
->from
= offset
- pos
;
139 p
= m
->op
->next(m
, p
, &index
);
149 m
->buf
= seq_buf_alloc(m
->size
<<= 1);
150 return !m
->buf
? -ENOMEM
: -EAGAIN
;
154 * seq_read - ->read() method for sequential files.
155 * @file: the file to read from
156 * @buf: the buffer to read to
157 * @size: the maximum number of bytes to read
158 * @ppos: the current position in the file
160 * Ready-made ->f_op->read()
162 ssize_t
seq_read(struct file
*file
, char __user
*buf
, size_t size
, loff_t
*ppos
)
164 struct seq_file
*m
= file
->private_data
;
171 mutex_lock(&m
->lock
);
174 * seq_file->op->..m_start/m_stop/m_next may do special actions
175 * or optimisations based on the file->f_version, so we want to
176 * pass the file->f_version to those methods.
178 * seq_file->version is just copy of f_version, and seq_file
179 * methods can treat it simply as file version.
180 * It is copied in first and copied out after all operations.
181 * It is convenient to have it as part of structure to avoid the
182 * need of passing another argument to all the seq_file methods.
184 m
->version
= file
->f_version
;
186 /* Don't assume *ppos is where we left it */
187 if (unlikely(*ppos
!= m
->read_pos
)) {
188 while ((err
= traverse(m
, *ppos
)) == -EAGAIN
)
191 /* With prejudice... */
202 /* grab buffer if we didn't have one */
204 m
->buf
= seq_buf_alloc(m
->size
= PAGE_SIZE
);
208 /* if not empty - flush it first */
210 n
= min(m
->count
, size
);
211 err
= copy_to_user(buf
, m
->buf
+ m
->from
, n
);
224 /* we need at least one record in buffer */
226 p
= m
->op
->start(m
, &pos
);
231 err
= m
->op
->show(m
, p
);
236 if (unlikely(!m
->count
)) {
237 p
= m
->op
->next(m
, p
, &pos
);
241 if (m
->count
< m
->size
)
246 m
->buf
= seq_buf_alloc(m
->size
<<= 1);
251 p
= m
->op
->start(m
, &pos
);
257 /* they want more? let's try to get some more */
258 while (m
->count
< size
) {
259 size_t offs
= m
->count
;
261 p
= m
->op
->next(m
, p
, &next
);
262 if (!p
|| IS_ERR(p
)) {
266 err
= m
->op
->show(m
, p
);
267 if (seq_has_overflowed(m
) || err
) {
269 if (likely(err
<= 0))
275 n
= min(m
->count
, size
);
276 err
= copy_to_user(buf
, m
->buf
, n
);
291 m
->read_pos
+= copied
;
293 file
->f_version
= m
->version
;
294 mutex_unlock(&m
->lock
);
303 EXPORT_SYMBOL(seq_read
);
306 * seq_lseek - ->llseek() method for sequential files.
307 * @file: the file in question
308 * @offset: new position
309 * @whence: 0 for absolute, 1 for relative position
311 * Ready-made ->f_op->llseek()
313 loff_t
seq_lseek(struct file
*file
, loff_t offset
, int whence
)
315 struct seq_file
*m
= file
->private_data
;
316 loff_t retval
= -EINVAL
;
318 mutex_lock(&m
->lock
);
319 m
->version
= file
->f_version
;
322 offset
+= file
->f_pos
;
327 if (offset
!= m
->read_pos
) {
328 while ((retval
= traverse(m
, offset
)) == -EAGAIN
)
331 /* with extreme prejudice... */
338 m
->read_pos
= offset
;
339 retval
= file
->f_pos
= offset
;
342 file
->f_pos
= offset
;
345 file
->f_version
= m
->version
;
346 mutex_unlock(&m
->lock
);
349 EXPORT_SYMBOL(seq_lseek
);
352 * seq_release - free the structures associated with sequential file.
353 * @file: file in question
356 * Frees the structures associated with sequential file; can be used
357 * as ->f_op->release() if you don't have private data to destroy.
359 int seq_release(struct inode
*inode
, struct file
*file
)
361 struct seq_file
*m
= file
->private_data
;
366 EXPORT_SYMBOL(seq_release
);
369 * seq_escape - print string into buffer, escaping some characters
372 * @esc: set of characters that need escaping
374 * Puts string into buffer, replacing each occurrence of character from
375 * @esc with usual octal escape. Returns 0 in case of success, -1 - in
378 int seq_escape(struct seq_file
*m
, const char *s
, const char *esc
)
380 char *end
= m
->buf
+ m
->size
;
384 for (p
= m
->buf
+ m
->count
; (c
= *s
) != '\0' && p
< end
; s
++) {
385 if (!strchr(esc
, c
)) {
391 *p
++ = '0' + ((c
& 0300) >> 6);
392 *p
++ = '0' + ((c
& 070) >> 3);
393 *p
++ = '0' + (c
& 07);
399 m
->count
= p
- m
->buf
;
402 EXPORT_SYMBOL(seq_escape
);
404 int seq_vprintf(struct seq_file
*m
, const char *f
, va_list args
)
408 if (m
->count
< m
->size
) {
409 len
= vsnprintf(m
->buf
+ m
->count
, m
->size
- m
->count
, f
, args
);
410 if (m
->count
+ len
< m
->size
) {
418 EXPORT_SYMBOL(seq_vprintf
);
420 int seq_printf(struct seq_file
*m
, const char *f
, ...)
426 ret
= seq_vprintf(m
, f
, args
);
431 EXPORT_SYMBOL(seq_printf
);
434 * mangle_path - mangle and copy path to buffer beginning
436 * @p: beginning of path in above buffer
437 * @esc: set of characters that need escaping
439 * Copy the path from @p to @s, replacing each occurrence of character from
440 * @esc with usual octal escape.
441 * Returns pointer past last written character in @s, or NULL in case of
444 char *mangle_path(char *s
, const char *p
, const char *esc
)
450 } else if (!strchr(esc
, c
)) {
452 } else if (s
+ 4 > p
) {
456 *s
++ = '0' + ((c
& 0300) >> 6);
457 *s
++ = '0' + ((c
& 070) >> 3);
458 *s
++ = '0' + (c
& 07);
463 EXPORT_SYMBOL(mangle_path
);
466 * seq_path - seq_file interface to print a pathname
467 * @m: the seq_file handle
468 * @path: the struct path to print
469 * @esc: set of characters to escape in the output
471 * return the absolute path of 'path', as represented by the
472 * dentry / mnt pair in the path parameter.
474 int seq_path(struct seq_file
*m
, const struct path
*path
, const char *esc
)
477 size_t size
= seq_get_buf(m
, &buf
);
481 char *p
= d_path(path
, buf
, size
);
483 char *end
= mangle_path(buf
, p
, esc
);
492 EXPORT_SYMBOL(seq_path
);
495 * seq_file_path - seq_file interface to print a pathname of a file
496 * @m: the seq_file handle
497 * @file: the struct file to print
498 * @esc: set of characters to escape in the output
500 * return the absolute path to the file.
502 int seq_file_path(struct seq_file
*m
, struct file
*file
, const char *esc
)
504 return seq_path(m
, &file
->f_path
, esc
);
506 EXPORT_SYMBOL(seq_file_path
);
509 * Same as seq_path, but relative to supplied root.
511 int seq_path_root(struct seq_file
*m
, const struct path
*path
,
512 const struct path
*root
, const char *esc
)
515 size_t size
= seq_get_buf(m
, &buf
);
516 int res
= -ENAMETOOLONG
;
521 p
= __d_path(path
, root
, buf
, size
);
526 char *end
= mangle_path(buf
, p
, esc
);
535 return res
< 0 && res
!= -ENAMETOOLONG
? res
: 0;
539 * returns the path of the 'dentry' from the root of its filesystem.
541 int seq_dentry(struct seq_file
*m
, struct dentry
*dentry
, const char *esc
)
544 size_t size
= seq_get_buf(m
, &buf
);
548 char *p
= dentry_path(dentry
, buf
, size
);
550 char *end
= mangle_path(buf
, p
, esc
);
559 EXPORT_SYMBOL(seq_dentry
);
561 static void *single_start(struct seq_file
*p
, loff_t
*pos
)
563 return NULL
+ (*pos
== 0);
566 static void *single_next(struct seq_file
*p
, void *v
, loff_t
*pos
)
572 static void single_stop(struct seq_file
*p
, void *v
)
576 int single_open(struct file
*file
, int (*show
)(struct seq_file
*, void *),
579 struct seq_operations
*op
= kmalloc(sizeof(*op
), GFP_KERNEL
);
583 op
->start
= single_start
;
584 op
->next
= single_next
;
585 op
->stop
= single_stop
;
587 res
= seq_open(file
, op
);
589 ((struct seq_file
*)file
->private_data
)->private = data
;
595 EXPORT_SYMBOL(single_open
);
597 int single_open_size(struct file
*file
, int (*show
)(struct seq_file
*, void *),
598 void *data
, size_t size
)
600 char *buf
= seq_buf_alloc(size
);
604 ret
= single_open(file
, show
, data
);
609 ((struct seq_file
*)file
->private_data
)->buf
= buf
;
610 ((struct seq_file
*)file
->private_data
)->size
= size
;
613 EXPORT_SYMBOL(single_open_size
);
615 int single_release(struct inode
*inode
, struct file
*file
)
617 const struct seq_operations
*op
= ((struct seq_file
*)file
->private_data
)->op
;
618 int res
= seq_release(inode
, file
);
622 EXPORT_SYMBOL(single_release
);
624 int seq_release_private(struct inode
*inode
, struct file
*file
)
626 struct seq_file
*seq
= file
->private_data
;
630 return seq_release(inode
, file
);
632 EXPORT_SYMBOL(seq_release_private
);
634 void *__seq_open_private(struct file
*f
, const struct seq_operations
*ops
,
639 struct seq_file
*seq
;
641 private = kzalloc(psize
, GFP_KERNEL
);
645 rc
= seq_open(f
, ops
);
649 seq
= f
->private_data
;
650 seq
->private = private;
658 EXPORT_SYMBOL(__seq_open_private
);
660 int seq_open_private(struct file
*filp
, const struct seq_operations
*ops
,
663 return __seq_open_private(filp
, ops
, psize
) ? 0 : -ENOMEM
;
665 EXPORT_SYMBOL(seq_open_private
);
667 int seq_putc(struct seq_file
*m
, char c
)
669 if (m
->count
< m
->size
) {
670 m
->buf
[m
->count
++] = c
;
675 EXPORT_SYMBOL(seq_putc
);
677 int seq_puts(struct seq_file
*m
, const char *s
)
680 if (m
->count
+ len
< m
->size
) {
681 memcpy(m
->buf
+ m
->count
, s
, len
);
688 EXPORT_SYMBOL(seq_puts
);
691 * A helper routine for putting decimal numbers without rich format of printf().
692 * only 'unsigned long long' is supported.
693 * This routine will put one byte delimiter + number into seq_file.
694 * This routine is very quick when you show lots of numbers.
695 * In usual cases, it will be better to use seq_printf(). It's easier to read.
697 int seq_put_decimal_ull(struct seq_file
*m
, char delimiter
,
698 unsigned long long num
)
702 if (m
->count
+ 2 >= m
->size
) /* we'll write 2 bytes at least */
706 m
->buf
[m
->count
++] = delimiter
;
709 m
->buf
[m
->count
++] = num
+ '0';
713 len
= num_to_str(m
->buf
+ m
->count
, m
->size
- m
->count
, num
);
722 EXPORT_SYMBOL(seq_put_decimal_ull
);
724 int seq_put_decimal_ll(struct seq_file
*m
, char delimiter
,
728 if (m
->count
+ 3 >= m
->size
) {
733 m
->buf
[m
->count
++] = delimiter
;
737 return seq_put_decimal_ull(m
, delimiter
, num
);
740 EXPORT_SYMBOL(seq_put_decimal_ll
);
743 * seq_write - write arbitrary data to buffer
744 * @seq: seq_file identifying the buffer to which data should be written
745 * @data: data address
746 * @len: number of bytes
748 * Return 0 on success, non-zero otherwise.
750 int seq_write(struct seq_file
*seq
, const void *data
, size_t len
)
752 if (seq
->count
+ len
< seq
->size
) {
753 memcpy(seq
->buf
+ seq
->count
, data
, len
);
757 seq_set_overflow(seq
);
760 EXPORT_SYMBOL(seq_write
);
763 * seq_pad - write padding spaces to buffer
764 * @m: seq_file identifying the buffer to which data should be written
765 * @c: the byte to append after padding if non-zero
767 void seq_pad(struct seq_file
*m
, char c
)
769 int size
= m
->pad_until
- m
->count
;
771 seq_printf(m
, "%*s", size
, "");
775 EXPORT_SYMBOL(seq_pad
);
777 /* A complete analogue of print_hex_dump() */
778 void seq_hex_dump(struct seq_file
*m
, const char *prefix_str
, int prefix_type
,
779 int rowsize
, int groupsize
, const void *buf
, size_t len
,
783 int i
, linelen
, remaining
= len
;
786 if (rowsize
!= 16 && rowsize
!= 32)
789 for (i
= 0; i
< len
&& !seq_has_overflowed(m
); i
+= rowsize
) {
790 linelen
= min(remaining
, rowsize
);
791 remaining
-= rowsize
;
793 switch (prefix_type
) {
794 case DUMP_PREFIX_ADDRESS
:
795 seq_printf(m
, "%s%p: ", prefix_str
, ptr
+ i
);
797 case DUMP_PREFIX_OFFSET
:
798 seq_printf(m
, "%s%.8x: ", prefix_str
, i
);
801 seq_printf(m
, "%s", prefix_str
);
805 ret
= hex_dump_to_buffer(ptr
+ i
, linelen
, rowsize
, groupsize
,
806 m
->buf
+ m
->count
, m
->size
- m
->count
,
808 if (ret
>= m
->size
- m
->count
) {
816 EXPORT_SYMBOL(seq_hex_dump
);
818 struct list_head
*seq_list_start(struct list_head
*head
, loff_t pos
)
820 struct list_head
*lh
;
822 list_for_each(lh
, head
)
828 EXPORT_SYMBOL(seq_list_start
);
830 struct list_head
*seq_list_start_head(struct list_head
*head
, loff_t pos
)
835 return seq_list_start(head
, pos
- 1);
837 EXPORT_SYMBOL(seq_list_start_head
);
839 struct list_head
*seq_list_next(void *v
, struct list_head
*head
, loff_t
*ppos
)
841 struct list_head
*lh
;
843 lh
= ((struct list_head
*)v
)->next
;
845 return lh
== head
? NULL
: lh
;
847 EXPORT_SYMBOL(seq_list_next
);
850 * seq_hlist_start - start an iteration of a hlist
851 * @head: the head of the hlist
852 * @pos: the start position of the sequence
854 * Called at seq_file->op->start().
856 struct hlist_node
*seq_hlist_start(struct hlist_head
*head
, loff_t pos
)
858 struct hlist_node
*node
;
860 hlist_for_each(node
, head
)
865 EXPORT_SYMBOL(seq_hlist_start
);
868 * seq_hlist_start_head - start an iteration of a hlist
869 * @head: the head of the hlist
870 * @pos: the start position of the sequence
872 * Called at seq_file->op->start(). Call this function if you want to
873 * print a header at the top of the output.
875 struct hlist_node
*seq_hlist_start_head(struct hlist_head
*head
, loff_t pos
)
878 return SEQ_START_TOKEN
;
880 return seq_hlist_start(head
, pos
- 1);
882 EXPORT_SYMBOL(seq_hlist_start_head
);
885 * seq_hlist_next - move to the next position of the hlist
886 * @v: the current iterator
887 * @head: the head of the hlist
888 * @ppos: the current position
890 * Called at seq_file->op->next().
892 struct hlist_node
*seq_hlist_next(void *v
, struct hlist_head
*head
,
895 struct hlist_node
*node
= v
;
898 if (v
== SEQ_START_TOKEN
)
903 EXPORT_SYMBOL(seq_hlist_next
);
906 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
907 * @head: the head of the hlist
908 * @pos: the start position of the sequence
910 * Called at seq_file->op->start().
912 * This list-traversal primitive may safely run concurrently with
913 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
914 * as long as the traversal is guarded by rcu_read_lock().
916 struct hlist_node
*seq_hlist_start_rcu(struct hlist_head
*head
,
919 struct hlist_node
*node
;
921 __hlist_for_each_rcu(node
, head
)
926 EXPORT_SYMBOL(seq_hlist_start_rcu
);
929 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
930 * @head: the head of the hlist
931 * @pos: the start position of the sequence
933 * Called at seq_file->op->start(). Call this function if you want to
934 * print a header at the top of the output.
936 * This list-traversal primitive may safely run concurrently with
937 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
938 * as long as the traversal is guarded by rcu_read_lock().
940 struct hlist_node
*seq_hlist_start_head_rcu(struct hlist_head
*head
,
944 return SEQ_START_TOKEN
;
946 return seq_hlist_start_rcu(head
, pos
- 1);
948 EXPORT_SYMBOL(seq_hlist_start_head_rcu
);
951 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
952 * @v: the current iterator
953 * @head: the head of the hlist
954 * @ppos: the current position
956 * Called at seq_file->op->next().
958 * This list-traversal primitive may safely run concurrently with
959 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
960 * as long as the traversal is guarded by rcu_read_lock().
962 struct hlist_node
*seq_hlist_next_rcu(void *v
,
963 struct hlist_head
*head
,
966 struct hlist_node
*node
= v
;
969 if (v
== SEQ_START_TOKEN
)
970 return rcu_dereference(head
->first
);
972 return rcu_dereference(node
->next
);
974 EXPORT_SYMBOL(seq_hlist_next_rcu
);
977 * seq_hlist_start_precpu - start an iteration of a percpu hlist array
978 * @head: pointer to percpu array of struct hlist_heads
979 * @cpu: pointer to cpu "cursor"
980 * @pos: start position of sequence
982 * Called at seq_file->op->start().
985 seq_hlist_start_percpu(struct hlist_head __percpu
*head
, int *cpu
, loff_t pos
)
987 struct hlist_node
*node
;
989 for_each_possible_cpu(*cpu
) {
990 hlist_for_each(node
, per_cpu_ptr(head
, *cpu
)) {
997 EXPORT_SYMBOL(seq_hlist_start_percpu
);
1000 * seq_hlist_next_percpu - move to the next position of the percpu hlist array
1001 * @v: pointer to current hlist_node
1002 * @head: pointer to percpu array of struct hlist_heads
1003 * @cpu: pointer to cpu "cursor"
1004 * @pos: start position of sequence
1006 * Called at seq_file->op->next().
1009 seq_hlist_next_percpu(void *v
, struct hlist_head __percpu
*head
,
1010 int *cpu
, loff_t
*pos
)
1012 struct hlist_node
*node
= v
;
1019 for (*cpu
= cpumask_next(*cpu
, cpu_possible_mask
); *cpu
< nr_cpu_ids
;
1020 *cpu
= cpumask_next(*cpu
, cpu_possible_mask
)) {
1021 struct hlist_head
*bucket
= per_cpu_ptr(head
, *cpu
);
1023 if (!hlist_empty(bucket
))
1024 return bucket
->first
;
1028 EXPORT_SYMBOL(seq_hlist_next_percpu
);