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)
28 buf = kmalloc(size, GFP_KERNEL | __GFP_NOWARN);
29 if (!buf && size > PAGE_SIZE)
35 * seq_open - initialize sequential file
36 * @file: file we initialize
37 * @op: method table describing the sequence
39 * seq_open() sets @file, associating it with a sequence described
40 * by @op. @op->start() sets the iterator up and returns the first
41 * element of sequence. @op->stop() shuts it down. @op->next()
42 * returns the next element of sequence. @op->show() prints element
43 * into the buffer. In case of error ->start() and ->next() return
44 * ERR_PTR(error). In the end of sequence they return %NULL. ->show()
45 * returns 0 in case of success and negative number in case of error.
46 * Returning SEQ_SKIP means "discard this element and move on".
48 int seq_open(struct file *file, const struct seq_operations *op)
50 struct seq_file *p = file->private_data;
53 p = kmalloc(sizeof(*p), GFP_KERNEL);
56 file->private_data = p;
58 memset(p, 0, sizeof(*p));
62 p->user_ns = file->f_cred->user_ns;
66 * Wrappers around seq_open(e.g. swaps_open) need to be
67 * aware of this. If they set f_version themselves, they
68 * should call seq_open first and then set f_version.
73 * seq_files support lseek() and pread(). They do not implement
74 * write() at all, but we clear FMODE_PWRITE here for historical
77 * If a client of seq_files a) implements file.write() and b) wishes to
78 * support pwrite() then that client will need to implement its own
79 * file.open() which calls seq_open() and then sets FMODE_PWRITE.
81 file->f_mode &= ~FMODE_PWRITE;
84 EXPORT_SYMBOL(seq_open);
86 static int traverse(struct seq_file *m, loff_t offset)
88 loff_t pos = 0, index;
94 m->count = m->from = 0;
100 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
104 p = m->op->start(m, &index);
109 error = m->op->show(m, p);
112 if (unlikely(error)) {
116 if (seq_has_overflowed(m))
118 if (pos + m->count > offset) {
119 m->from = offset - pos;
131 p = m->op->next(m, p, &index);
141 m->buf = seq_buf_alloc(m->size <<= 1);
142 return !m->buf ? -ENOMEM : -EAGAIN;
146 * seq_read - ->read() method for sequential files.
147 * @file: the file to read from
148 * @buf: the buffer to read to
149 * @size: the maximum number of bytes to read
150 * @ppos: the current position in the file
152 * Ready-made ->f_op->read()
154 ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
156 struct seq_file *m = file->private_data;
163 mutex_lock(&m->lock);
166 * seq_file->op->..m_start/m_stop/m_next may do special actions
167 * or optimisations based on the file->f_version, so we want to
168 * pass the file->f_version to those methods.
170 * seq_file->version is just copy of f_version, and seq_file
171 * methods can treat it simply as file version.
172 * It is copied in first and copied out after all operations.
173 * It is convenient to have it as part of structure to avoid the
174 * need of passing another argument to all the seq_file methods.
176 m->version = file->f_version;
178 /* Don't assume *ppos is where we left it */
179 if (unlikely(*ppos != m->read_pos)) {
180 while ((err = traverse(m, *ppos)) == -EAGAIN)
183 /* With prejudice... */
194 /* grab buffer if we didn't have one */
196 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
200 /* if not empty - flush it first */
202 n = min(m->count, size);
203 err = copy_to_user(buf, m->buf + m->from, n);
216 /* we need at least one record in buffer */
218 p = m->op->start(m, &pos);
223 err = m->op->show(m, p);
228 if (unlikely(!m->count)) {
229 p = m->op->next(m, p, &pos);
233 if (m->count < m->size)
238 m->buf = seq_buf_alloc(m->size <<= 1);
243 p = m->op->start(m, &pos);
249 /* they want more? let's try to get some more */
250 while (m->count < size) {
251 size_t offs = m->count;
253 p = m->op->next(m, p, &next);
254 if (!p || IS_ERR(p)) {
258 err = m->op->show(m, p);
259 if (seq_has_overflowed(m) || err) {
261 if (likely(err <= 0))
267 n = min(m->count, size);
268 err = copy_to_user(buf, m->buf, n);
283 m->read_pos += copied;
285 file->f_version = m->version;
286 mutex_unlock(&m->lock);
295 EXPORT_SYMBOL(seq_read);
298 * seq_lseek - ->llseek() method for sequential files.
299 * @file: the file in question
300 * @offset: new position
301 * @whence: 0 for absolute, 1 for relative position
303 * Ready-made ->f_op->llseek()
305 loff_t seq_lseek(struct file *file, loff_t offset, int whence)
307 struct seq_file *m = file->private_data;
308 loff_t retval = -EINVAL;
310 mutex_lock(&m->lock);
311 m->version = file->f_version;
314 offset += file->f_pos;
319 if (offset != m->read_pos) {
320 while ((retval = traverse(m, offset)) == -EAGAIN)
323 /* with extreme prejudice... */
330 m->read_pos = offset;
331 retval = file->f_pos = offset;
334 file->f_pos = offset;
337 file->f_version = m->version;
338 mutex_unlock(&m->lock);
341 EXPORT_SYMBOL(seq_lseek);
344 * seq_release - free the structures associated with sequential file.
345 * @file: file in question
348 * Frees the structures associated with sequential file; can be used
349 * as ->f_op->release() if you don't have private data to destroy.
351 int seq_release(struct inode *inode, struct file *file)
353 struct seq_file *m = file->private_data;
358 EXPORT_SYMBOL(seq_release);
361 * seq_escape - print string into buffer, escaping some characters
364 * @esc: set of characters that need escaping
366 * Puts string into buffer, replacing each occurrence of character from
367 * @esc with usual octal escape. Returns 0 in case of success, -1 - in
370 int seq_escape(struct seq_file *m, const char *s, const char *esc)
372 char *end = m->buf + m->size;
376 for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) {
377 if (!strchr(esc, c)) {
383 *p++ = '0' + ((c & 0300) >> 6);
384 *p++ = '0' + ((c & 070) >> 3);
385 *p++ = '0' + (c & 07);
391 m->count = p - m->buf;
394 EXPORT_SYMBOL(seq_escape);
396 int seq_vprintf(struct seq_file *m, const char *f, va_list args)
400 if (m->count < m->size) {
401 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
402 if (m->count + len < m->size) {
410 EXPORT_SYMBOL(seq_vprintf);
412 int seq_printf(struct seq_file *m, const char *f, ...)
418 ret = seq_vprintf(m, f, args);
423 EXPORT_SYMBOL(seq_printf);
426 * mangle_path - mangle and copy path to buffer beginning
428 * @p: beginning of path in above buffer
429 * @esc: set of characters that need escaping
431 * Copy the path from @p to @s, replacing each occurrence of character from
432 * @esc with usual octal escape.
433 * Returns pointer past last written character in @s, or NULL in case of
436 char *mangle_path(char *s, const char *p, const char *esc)
442 } else if (!strchr(esc, c)) {
444 } else if (s + 4 > p) {
448 *s++ = '0' + ((c & 0300) >> 6);
449 *s++ = '0' + ((c & 070) >> 3);
450 *s++ = '0' + (c & 07);
455 EXPORT_SYMBOL(mangle_path);
458 * seq_path - seq_file interface to print a pathname
459 * @m: the seq_file handle
460 * @path: the struct path to print
461 * @esc: set of characters to escape in the output
463 * return the absolute path of 'path', as represented by the
464 * dentry / mnt pair in the path parameter.
466 int seq_path(struct seq_file *m, const struct path *path, const char *esc)
469 size_t size = seq_get_buf(m, &buf);
473 char *p = d_path(path, buf, size);
475 char *end = mangle_path(buf, p, esc);
484 EXPORT_SYMBOL(seq_path);
487 * Same as seq_path, but relative to supplied root.
489 int seq_path_root(struct seq_file *m, const struct path *path,
490 const struct path *root, const char *esc)
493 size_t size = seq_get_buf(m, &buf);
494 int res = -ENAMETOOLONG;
499 p = __d_path(path, root, buf, size);
504 char *end = mangle_path(buf, p, esc);
513 return res < 0 && res != -ENAMETOOLONG ? res : 0;
517 * returns the path of the 'dentry' from the root of its filesystem.
519 int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
522 size_t size = seq_get_buf(m, &buf);
526 char *p = dentry_path(dentry, buf, size);
528 char *end = mangle_path(buf, p, esc);
538 int seq_bitmap(struct seq_file *m, const unsigned long *bits,
539 unsigned int nr_bits)
541 if (m->count < m->size) {
542 int len = bitmap_scnprintf(m->buf + m->count,
543 m->size - m->count, bits, nr_bits);
544 if (m->count + len < m->size) {
552 EXPORT_SYMBOL(seq_bitmap);
554 int seq_bitmap_list(struct seq_file *m, const unsigned long *bits,
555 unsigned int nr_bits)
557 if (m->count < m->size) {
558 int len = bitmap_scnlistprintf(m->buf + m->count,
559 m->size - m->count, bits, nr_bits);
560 if (m->count + len < m->size) {
568 EXPORT_SYMBOL(seq_bitmap_list);
570 static void *single_start(struct seq_file *p, loff_t *pos)
572 return NULL + (*pos == 0);
575 static void *single_next(struct seq_file *p, void *v, loff_t *pos)
581 static void single_stop(struct seq_file *p, void *v)
585 int single_open(struct file *file, int (*show)(struct seq_file *, void *),
588 struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL);
592 op->start = single_start;
593 op->next = single_next;
594 op->stop = single_stop;
596 res = seq_open(file, op);
598 ((struct seq_file *)file->private_data)->private = data;
604 EXPORT_SYMBOL(single_open);
606 int single_open_size(struct file *file, int (*show)(struct seq_file *, void *),
607 void *data, size_t size)
609 char *buf = seq_buf_alloc(size);
613 ret = single_open(file, show, data);
618 ((struct seq_file *)file->private_data)->buf = buf;
619 ((struct seq_file *)file->private_data)->size = size;
622 EXPORT_SYMBOL(single_open_size);
624 int single_release(struct inode *inode, struct file *file)
626 const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
627 int res = seq_release(inode, file);
631 EXPORT_SYMBOL(single_release);
633 int seq_release_private(struct inode *inode, struct file *file)
635 struct seq_file *seq = file->private_data;
639 return seq_release(inode, file);
641 EXPORT_SYMBOL(seq_release_private);
643 void *__seq_open_private(struct file *f, const struct seq_operations *ops,
648 struct seq_file *seq;
650 private = kzalloc(psize, GFP_KERNEL);
654 rc = seq_open(f, ops);
658 seq = f->private_data;
659 seq->private = private;
667 EXPORT_SYMBOL(__seq_open_private);
669 int seq_open_private(struct file *filp, const struct seq_operations *ops,
672 return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM;
674 EXPORT_SYMBOL(seq_open_private);
676 int seq_putc(struct seq_file *m, char c)
678 if (m->count < m->size) {
679 m->buf[m->count++] = c;
684 EXPORT_SYMBOL(seq_putc);
686 int seq_puts(struct seq_file *m, const char *s)
689 if (m->count + len < m->size) {
690 memcpy(m->buf + m->count, s, len);
697 EXPORT_SYMBOL(seq_puts);
700 * A helper routine for putting decimal numbers without rich format of printf().
701 * only 'unsigned long long' is supported.
702 * This routine will put one byte delimiter + number into seq_file.
703 * This routine is very quick when you show lots of numbers.
704 * In usual cases, it will be better to use seq_printf(). It's easier to read.
706 int seq_put_decimal_ull(struct seq_file *m, char delimiter,
707 unsigned long long num)
711 if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
715 m->buf[m->count++] = delimiter;
718 m->buf[m->count++] = num + '0';
722 len = num_to_str(m->buf + m->count, m->size - m->count, num);
731 EXPORT_SYMBOL(seq_put_decimal_ull);
733 int seq_put_decimal_ll(struct seq_file *m, char delimiter,
737 if (m->count + 3 >= m->size) {
742 m->buf[m->count++] = delimiter;
746 return seq_put_decimal_ull(m, delimiter, num);
749 EXPORT_SYMBOL(seq_put_decimal_ll);
752 * seq_write - write arbitrary data to buffer
753 * @seq: seq_file identifying the buffer to which data should be written
754 * @data: data address
755 * @len: number of bytes
757 * Return 0 on success, non-zero otherwise.
759 int seq_write(struct seq_file *seq, const void *data, size_t len)
761 if (seq->count + len < seq->size) {
762 memcpy(seq->buf + seq->count, data, len);
766 seq_set_overflow(seq);
769 EXPORT_SYMBOL(seq_write);
772 * seq_pad - write padding spaces to buffer
773 * @m: seq_file identifying the buffer to which data should be written
774 * @c: the byte to append after padding if non-zero
776 void seq_pad(struct seq_file *m, char c)
778 int size = m->pad_until - m->count;
780 seq_printf(m, "%*s", size, "");
784 EXPORT_SYMBOL(seq_pad);
786 struct list_head *seq_list_start(struct list_head *head, loff_t pos)
788 struct list_head *lh;
790 list_for_each(lh, head)
796 EXPORT_SYMBOL(seq_list_start);
798 struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
803 return seq_list_start(head, pos - 1);
805 EXPORT_SYMBOL(seq_list_start_head);
807 struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
809 struct list_head *lh;
811 lh = ((struct list_head *)v)->next;
813 return lh == head ? NULL : lh;
815 EXPORT_SYMBOL(seq_list_next);
818 * seq_hlist_start - start an iteration of a hlist
819 * @head: the head of the hlist
820 * @pos: the start position of the sequence
822 * Called at seq_file->op->start().
824 struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
826 struct hlist_node *node;
828 hlist_for_each(node, head)
833 EXPORT_SYMBOL(seq_hlist_start);
836 * seq_hlist_start_head - start an iteration of a hlist
837 * @head: the head of the hlist
838 * @pos: the start position of the sequence
840 * Called at seq_file->op->start(). Call this function if you want to
841 * print a header at the top of the output.
843 struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
846 return SEQ_START_TOKEN;
848 return seq_hlist_start(head, pos - 1);
850 EXPORT_SYMBOL(seq_hlist_start_head);
853 * seq_hlist_next - move to the next position of the hlist
854 * @v: the current iterator
855 * @head: the head of the hlist
856 * @ppos: the current position
858 * Called at seq_file->op->next().
860 struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
863 struct hlist_node *node = v;
866 if (v == SEQ_START_TOKEN)
871 EXPORT_SYMBOL(seq_hlist_next);
874 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
875 * @head: the head of the hlist
876 * @pos: the start position of the sequence
878 * Called at seq_file->op->start().
880 * This list-traversal primitive may safely run concurrently with
881 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
882 * as long as the traversal is guarded by rcu_read_lock().
884 struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
887 struct hlist_node *node;
889 __hlist_for_each_rcu(node, head)
894 EXPORT_SYMBOL(seq_hlist_start_rcu);
897 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
898 * @head: the head of the hlist
899 * @pos: the start position of the sequence
901 * Called at seq_file->op->start(). Call this function if you want to
902 * print a header at the top of the output.
904 * This list-traversal primitive may safely run concurrently with
905 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
906 * as long as the traversal is guarded by rcu_read_lock().
908 struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
912 return SEQ_START_TOKEN;
914 return seq_hlist_start_rcu(head, pos - 1);
916 EXPORT_SYMBOL(seq_hlist_start_head_rcu);
919 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
920 * @v: the current iterator
921 * @head: the head of the hlist
922 * @ppos: the current position
924 * Called at seq_file->op->next().
926 * This list-traversal primitive may safely run concurrently with
927 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
928 * as long as the traversal is guarded by rcu_read_lock().
930 struct hlist_node *seq_hlist_next_rcu(void *v,
931 struct hlist_head *head,
934 struct hlist_node *node = v;
937 if (v == SEQ_START_TOKEN)
938 return rcu_dereference(head->first);
940 return rcu_dereference(node->next);
942 EXPORT_SYMBOL(seq_hlist_next_rcu);
945 * seq_hlist_start_precpu - start an iteration of a percpu hlist array
946 * @head: pointer to percpu array of struct hlist_heads
947 * @cpu: pointer to cpu "cursor"
948 * @pos: start position of sequence
950 * Called at seq_file->op->start().
953 seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
955 struct hlist_node *node;
957 for_each_possible_cpu(*cpu) {
958 hlist_for_each(node, per_cpu_ptr(head, *cpu)) {
965 EXPORT_SYMBOL(seq_hlist_start_percpu);
968 * seq_hlist_next_percpu - move to the next position of the percpu hlist array
969 * @v: pointer to current hlist_node
970 * @head: pointer to percpu array of struct hlist_heads
971 * @cpu: pointer to cpu "cursor"
972 * @pos: start position of sequence
974 * Called at seq_file->op->next().
977 seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head,
978 int *cpu, loff_t *pos)
980 struct hlist_node *node = v;
987 for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids;
988 *cpu = cpumask_next(*cpu, cpu_possible_mask)) {
989 struct hlist_head *bucket = per_cpu_ptr(head, *cpu);
991 if (!hlist_empty(bucket))
992 return bucket->first;
996 EXPORT_SYMBOL(seq_hlist_next_percpu);