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".
51 * Note: seq_open() will allocate a struct seq_file and store its
52 * pointer in @file->private_data. This pointer should not be modified.
54 int seq_open(struct file *file, const struct seq_operations *op)
58 WARN_ON(file->private_data);
60 p = kzalloc(sizeof(*p), GFP_KERNEL);
64 file->private_data = p;
69 p->user_ns = file->f_cred->user_ns;
73 * Wrappers around seq_open(e.g. swaps_open) need to be
74 * aware of this. If they set f_version themselves, they
75 * should call seq_open first and then set f_version.
80 * seq_files support lseek() and pread(). They do not implement
81 * write() at all, but we clear FMODE_PWRITE here for historical
84 * If a client of seq_files a) implements file.write() and b) wishes to
85 * support pwrite() then that client will need to implement its own
86 * file.open() which calls seq_open() and then sets FMODE_PWRITE.
88 file->f_mode &= ~FMODE_PWRITE;
91 EXPORT_SYMBOL(seq_open);
93 static int traverse(struct seq_file *m, loff_t offset)
95 loff_t pos = 0, index;
101 m->count = m->from = 0;
107 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
111 p = m->op->start(m, &index);
116 error = m->op->show(m, p);
119 if (unlikely(error)) {
123 if (seq_has_overflowed(m))
125 if (pos + m->count > offset) {
126 m->from = offset - pos;
138 p = m->op->next(m, p, &index);
148 m->buf = seq_buf_alloc(m->size <<= 1);
149 return !m->buf ? -ENOMEM : -EAGAIN;
153 * seq_read - ->read() method for sequential files.
154 * @file: the file to read from
155 * @buf: the buffer to read to
156 * @size: the maximum number of bytes to read
157 * @ppos: the current position in the file
159 * Ready-made ->f_op->read()
161 ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
163 struct seq_file *m = file->private_data;
170 mutex_lock(&m->lock);
173 * seq_file->op->..m_start/m_stop/m_next may do special actions
174 * or optimisations based on the file->f_version, so we want to
175 * pass the file->f_version to those methods.
177 * seq_file->version is just copy of f_version, and seq_file
178 * methods can treat it simply as file version.
179 * It is copied in first and copied out after all operations.
180 * It is convenient to have it as part of structure to avoid the
181 * need of passing another argument to all the seq_file methods.
183 m->version = file->f_version;
185 /* Don't assume *ppos is where we left it */
186 if (unlikely(*ppos != m->read_pos)) {
187 while ((err = traverse(m, *ppos)) == -EAGAIN)
190 /* With prejudice... */
201 /* grab buffer if we didn't have one */
203 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
207 /* if not empty - flush it first */
209 n = min(m->count, size);
210 err = copy_to_user(buf, m->buf + m->from, n);
223 /* we need at least one record in buffer */
225 p = m->op->start(m, &pos);
230 err = m->op->show(m, p);
235 if (unlikely(!m->count)) {
236 p = m->op->next(m, p, &pos);
240 if (m->count < m->size)
245 m->buf = seq_buf_alloc(m->size <<= 1);
250 p = m->op->start(m, &pos);
256 /* they want more? let's try to get some more */
257 while (m->count < size) {
258 size_t offs = m->count;
260 p = m->op->next(m, p, &next);
261 if (!p || IS_ERR(p)) {
265 err = m->op->show(m, p);
266 if (seq_has_overflowed(m) || err) {
268 if (likely(err <= 0))
274 n = min(m->count, size);
275 err = copy_to_user(buf, m->buf, n);
290 m->read_pos += copied;
292 file->f_version = m->version;
293 mutex_unlock(&m->lock);
302 EXPORT_SYMBOL(seq_read);
305 * seq_lseek - ->llseek() method for sequential files.
306 * @file: the file in question
307 * @offset: new position
308 * @whence: 0 for absolute, 1 for relative position
310 * Ready-made ->f_op->llseek()
312 loff_t seq_lseek(struct file *file, loff_t offset, int whence)
314 struct seq_file *m = file->private_data;
315 loff_t retval = -EINVAL;
317 mutex_lock(&m->lock);
318 m->version = file->f_version;
321 offset += file->f_pos;
326 if (offset != m->read_pos) {
327 while ((retval = traverse(m, offset)) == -EAGAIN)
330 /* with extreme prejudice... */
337 m->read_pos = offset;
338 retval = file->f_pos = offset;
341 file->f_pos = offset;
344 file->f_version = m->version;
345 mutex_unlock(&m->lock);
348 EXPORT_SYMBOL(seq_lseek);
351 * seq_release - free the structures associated with sequential file.
352 * @file: file in question
355 * Frees the structures associated with sequential file; can be used
356 * as ->f_op->release() if you don't have private data to destroy.
358 int seq_release(struct inode *inode, struct file *file)
360 struct seq_file *m = file->private_data;
365 EXPORT_SYMBOL(seq_release);
368 * seq_escape - print string into buffer, escaping some characters
371 * @esc: set of characters that need escaping
373 * Puts string into buffer, replacing each occurrence of character from
374 * @esc with usual octal escape. Returns 0 in case of success, -1 - in
377 int seq_escape(struct seq_file *m, const char *s, const char *esc)
379 char *end = m->buf + m->size;
383 for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) {
384 if (!strchr(esc, c)) {
390 *p++ = '0' + ((c & 0300) >> 6);
391 *p++ = '0' + ((c & 070) >> 3);
392 *p++ = '0' + (c & 07);
398 m->count = p - m->buf;
401 EXPORT_SYMBOL(seq_escape);
403 int seq_vprintf(struct seq_file *m, const char *f, va_list args)
407 if (m->count < m->size) {
408 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
409 if (m->count + len < m->size) {
417 EXPORT_SYMBOL(seq_vprintf);
419 int seq_printf(struct seq_file *m, const char *f, ...)
425 ret = seq_vprintf(m, f, args);
430 EXPORT_SYMBOL(seq_printf);
433 * mangle_path - mangle and copy path to buffer beginning
435 * @p: beginning of path in above buffer
436 * @esc: set of characters that need escaping
438 * Copy the path from @p to @s, replacing each occurrence of character from
439 * @esc with usual octal escape.
440 * Returns pointer past last written character in @s, or NULL in case of
443 char *mangle_path(char *s, const char *p, const char *esc)
449 } else if (!strchr(esc, c)) {
451 } else if (s + 4 > p) {
455 *s++ = '0' + ((c & 0300) >> 6);
456 *s++ = '0' + ((c & 070) >> 3);
457 *s++ = '0' + (c & 07);
462 EXPORT_SYMBOL(mangle_path);
465 * seq_path - seq_file interface to print a pathname
466 * @m: the seq_file handle
467 * @path: the struct path to print
468 * @esc: set of characters to escape in the output
470 * return the absolute path of 'path', as represented by the
471 * dentry / mnt pair in the path parameter.
473 int seq_path(struct seq_file *m, const struct path *path, const char *esc)
476 size_t size = seq_get_buf(m, &buf);
480 char *p = d_path(path, buf, size);
482 char *end = mangle_path(buf, p, esc);
491 EXPORT_SYMBOL(seq_path);
494 * Same as seq_path, but relative to supplied root.
496 int seq_path_root(struct seq_file *m, const struct path *path,
497 const struct path *root, const char *esc)
500 size_t size = seq_get_buf(m, &buf);
501 int res = -ENAMETOOLONG;
506 p = __d_path(path, root, buf, size);
511 char *end = mangle_path(buf, p, esc);
520 return res < 0 && res != -ENAMETOOLONG ? res : 0;
524 * returns the path of the 'dentry' from the root of its filesystem.
526 int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
529 size_t size = seq_get_buf(m, &buf);
533 char *p = dentry_path(dentry, buf, size);
535 char *end = mangle_path(buf, p, esc);
544 EXPORT_SYMBOL(seq_dentry);
546 static void *single_start(struct seq_file *p, loff_t *pos)
548 return NULL + (*pos == 0);
551 static void *single_next(struct seq_file *p, void *v, loff_t *pos)
557 static void single_stop(struct seq_file *p, void *v)
561 int single_open(struct file *file, int (*show)(struct seq_file *, void *),
564 struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL);
568 op->start = single_start;
569 op->next = single_next;
570 op->stop = single_stop;
572 res = seq_open(file, op);
574 ((struct seq_file *)file->private_data)->private = data;
580 EXPORT_SYMBOL(single_open);
582 int single_open_size(struct file *file, int (*show)(struct seq_file *, void *),
583 void *data, size_t size)
585 char *buf = seq_buf_alloc(size);
589 ret = single_open(file, show, data);
594 ((struct seq_file *)file->private_data)->buf = buf;
595 ((struct seq_file *)file->private_data)->size = size;
598 EXPORT_SYMBOL(single_open_size);
600 int single_release(struct inode *inode, struct file *file)
602 const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
603 int res = seq_release(inode, file);
607 EXPORT_SYMBOL(single_release);
609 int seq_release_private(struct inode *inode, struct file *file)
611 struct seq_file *seq = file->private_data;
615 return seq_release(inode, file);
617 EXPORT_SYMBOL(seq_release_private);
619 void *__seq_open_private(struct file *f, const struct seq_operations *ops,
624 struct seq_file *seq;
626 private = kzalloc(psize, GFP_KERNEL);
630 rc = seq_open(f, ops);
634 seq = f->private_data;
635 seq->private = private;
643 EXPORT_SYMBOL(__seq_open_private);
645 int seq_open_private(struct file *filp, const struct seq_operations *ops,
648 return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM;
650 EXPORT_SYMBOL(seq_open_private);
652 int seq_putc(struct seq_file *m, char c)
654 if (m->count < m->size) {
655 m->buf[m->count++] = c;
660 EXPORT_SYMBOL(seq_putc);
662 int seq_puts(struct seq_file *m, const char *s)
665 if (m->count + len < m->size) {
666 memcpy(m->buf + m->count, s, len);
673 EXPORT_SYMBOL(seq_puts);
676 * A helper routine for putting decimal numbers without rich format of printf().
677 * only 'unsigned long long' is supported.
678 * This routine will put one byte delimiter + number into seq_file.
679 * This routine is very quick when you show lots of numbers.
680 * In usual cases, it will be better to use seq_printf(). It's easier to read.
682 int seq_put_decimal_ull(struct seq_file *m, char delimiter,
683 unsigned long long num)
687 if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
691 m->buf[m->count++] = delimiter;
694 m->buf[m->count++] = num + '0';
698 len = num_to_str(m->buf + m->count, m->size - m->count, num);
707 EXPORT_SYMBOL(seq_put_decimal_ull);
709 int seq_put_decimal_ll(struct seq_file *m, char delimiter,
713 if (m->count + 3 >= m->size) {
718 m->buf[m->count++] = delimiter;
722 return seq_put_decimal_ull(m, delimiter, num);
725 EXPORT_SYMBOL(seq_put_decimal_ll);
728 * seq_write - write arbitrary data to buffer
729 * @seq: seq_file identifying the buffer to which data should be written
730 * @data: data address
731 * @len: number of bytes
733 * Return 0 on success, non-zero otherwise.
735 int seq_write(struct seq_file *seq, const void *data, size_t len)
737 if (seq->count + len < seq->size) {
738 memcpy(seq->buf + seq->count, data, len);
742 seq_set_overflow(seq);
745 EXPORT_SYMBOL(seq_write);
748 * seq_pad - write padding spaces to buffer
749 * @m: seq_file identifying the buffer to which data should be written
750 * @c: the byte to append after padding if non-zero
752 void seq_pad(struct seq_file *m, char c)
754 int size = m->pad_until - m->count;
756 seq_printf(m, "%*s", size, "");
760 EXPORT_SYMBOL(seq_pad);
762 struct list_head *seq_list_start(struct list_head *head, loff_t pos)
764 struct list_head *lh;
766 list_for_each(lh, head)
772 EXPORT_SYMBOL(seq_list_start);
774 struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
779 return seq_list_start(head, pos - 1);
781 EXPORT_SYMBOL(seq_list_start_head);
783 struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
785 struct list_head *lh;
787 lh = ((struct list_head *)v)->next;
789 return lh == head ? NULL : lh;
791 EXPORT_SYMBOL(seq_list_next);
794 * seq_hlist_start - start an iteration of a hlist
795 * @head: the head of the hlist
796 * @pos: the start position of the sequence
798 * Called at seq_file->op->start().
800 struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
802 struct hlist_node *node;
804 hlist_for_each(node, head)
809 EXPORT_SYMBOL(seq_hlist_start);
812 * seq_hlist_start_head - start an iteration of a hlist
813 * @head: the head of the hlist
814 * @pos: the start position of the sequence
816 * Called at seq_file->op->start(). Call this function if you want to
817 * print a header at the top of the output.
819 struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
822 return SEQ_START_TOKEN;
824 return seq_hlist_start(head, pos - 1);
826 EXPORT_SYMBOL(seq_hlist_start_head);
829 * seq_hlist_next - move to the next position of the hlist
830 * @v: the current iterator
831 * @head: the head of the hlist
832 * @ppos: the current position
834 * Called at seq_file->op->next().
836 struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
839 struct hlist_node *node = v;
842 if (v == SEQ_START_TOKEN)
847 EXPORT_SYMBOL(seq_hlist_next);
850 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
851 * @head: the head of the hlist
852 * @pos: the start position of the sequence
854 * Called at seq_file->op->start().
856 * This list-traversal primitive may safely run concurrently with
857 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
858 * as long as the traversal is guarded by rcu_read_lock().
860 struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
863 struct hlist_node *node;
865 __hlist_for_each_rcu(node, head)
870 EXPORT_SYMBOL(seq_hlist_start_rcu);
873 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
874 * @head: the head of the hlist
875 * @pos: the start position of the sequence
877 * Called at seq_file->op->start(). Call this function if you want to
878 * print a header at the top of the output.
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_head_rcu(struct hlist_head *head,
888 return SEQ_START_TOKEN;
890 return seq_hlist_start_rcu(head, pos - 1);
892 EXPORT_SYMBOL(seq_hlist_start_head_rcu);
895 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
896 * @v: the current iterator
897 * @head: the head of the hlist
898 * @ppos: the current position
900 * Called at seq_file->op->next().
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_next_rcu(void *v,
907 struct hlist_head *head,
910 struct hlist_node *node = v;
913 if (v == SEQ_START_TOKEN)
914 return rcu_dereference(head->first);
916 return rcu_dereference(node->next);
918 EXPORT_SYMBOL(seq_hlist_next_rcu);
921 * seq_hlist_start_precpu - start an iteration of a percpu hlist array
922 * @head: pointer to percpu array of struct hlist_heads
923 * @cpu: pointer to cpu "cursor"
924 * @pos: start position of sequence
926 * Called at seq_file->op->start().
929 seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
931 struct hlist_node *node;
933 for_each_possible_cpu(*cpu) {
934 hlist_for_each(node, per_cpu_ptr(head, *cpu)) {
941 EXPORT_SYMBOL(seq_hlist_start_percpu);
944 * seq_hlist_next_percpu - move to the next position of the percpu hlist array
945 * @v: pointer to current hlist_node
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->next().
953 seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head,
954 int *cpu, loff_t *pos)
956 struct hlist_node *node = v;
963 for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids;
964 *cpu = cpumask_next(*cpu, cpu_possible_mask)) {
965 struct hlist_head *bucket = per_cpu_ptr(head, *cpu);
967 if (!hlist_empty(bucket))
968 return bucket->first;
972 EXPORT_SYMBOL(seq_hlist_next_percpu);