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>
16 #include <linux/string_helpers.h>
18 #include <asm/uaccess.h>
21 static void seq_set_overflow(struct seq_file *m)
26 static void *seq_buf_alloc(unsigned long size)
29 gfp_t gfp = GFP_KERNEL;
32 * For high order allocations, use __GFP_NORETRY to avoid oom-killing -
33 * it's better to fall back to vmalloc() than to kill things. For small
34 * allocations, just use GFP_KERNEL which will oom kill, thus no need
35 * for vmalloc fallback.
38 gfp |= __GFP_NORETRY | __GFP_NOWARN;
39 buf = kmalloc(size, gfp);
40 if (!buf && size > PAGE_SIZE)
46 * seq_open - initialize sequential file
47 * @file: file we initialize
48 * @op: method table describing the sequence
50 * seq_open() sets @file, associating it with a sequence described
51 * by @op. @op->start() sets the iterator up and returns the first
52 * element of sequence. @op->stop() shuts it down. @op->next()
53 * returns the next element of sequence. @op->show() prints element
54 * into the buffer. In case of error ->start() and ->next() return
55 * ERR_PTR(error). In the end of sequence they return %NULL. ->show()
56 * returns 0 in case of success and negative number in case of error.
57 * Returning SEQ_SKIP means "discard this element and move on".
58 * Note: seq_open() will allocate a struct seq_file and store its
59 * pointer in @file->private_data. This pointer should not be modified.
61 int seq_open(struct file *file, const struct seq_operations *op)
65 WARN_ON(file->private_data);
67 p = kzalloc(sizeof(*p), GFP_KERNEL);
71 file->private_data = p;
76 p->user_ns = file->f_cred->user_ns;
80 * Wrappers around seq_open(e.g. swaps_open) need to be
81 * aware of this. If they set f_version themselves, they
82 * should call seq_open first and then set f_version.
87 * seq_files support lseek() and pread(). They do not implement
88 * write() at all, but we clear FMODE_PWRITE here for historical
91 * If a client of seq_files a) implements file.write() and b) wishes to
92 * support pwrite() then that client will need to implement its own
93 * file.open() which calls seq_open() and then sets FMODE_PWRITE.
95 file->f_mode &= ~FMODE_PWRITE;
98 EXPORT_SYMBOL(seq_open);
100 static int traverse(struct seq_file *m, loff_t offset)
102 loff_t pos = 0, index;
108 m->count = m->from = 0;
114 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
118 p = m->op->start(m, &index);
123 error = m->op->show(m, p);
126 if (unlikely(error)) {
130 if (seq_has_overflowed(m))
132 if (pos + m->count > offset) {
133 m->from = offset - pos;
145 p = m->op->next(m, p, &index);
155 m->buf = seq_buf_alloc(m->size <<= 1);
156 return !m->buf ? -ENOMEM : -EAGAIN;
160 * seq_read - ->read() method for sequential files.
161 * @file: the file to read from
162 * @buf: the buffer to read to
163 * @size: the maximum number of bytes to read
164 * @ppos: the current position in the file
166 * Ready-made ->f_op->read()
168 ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
170 struct seq_file *m = file->private_data;
177 mutex_lock(&m->lock);
180 * seq_file->op->..m_start/m_stop/m_next may do special actions
181 * or optimisations based on the file->f_version, so we want to
182 * pass the file->f_version to those methods.
184 * seq_file->version is just copy of f_version, and seq_file
185 * methods can treat it simply as file version.
186 * It is copied in first and copied out after all operations.
187 * It is convenient to have it as part of structure to avoid the
188 * need of passing another argument to all the seq_file methods.
190 m->version = file->f_version;
192 /* Don't assume *ppos is where we left it */
193 if (unlikely(*ppos != m->read_pos)) {
194 while ((err = traverse(m, *ppos)) == -EAGAIN)
197 /* With prejudice... */
208 /* grab buffer if we didn't have one */
210 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
214 /* if not empty - flush it first */
216 n = min(m->count, size);
217 err = copy_to_user(buf, m->buf + m->from, n);
230 /* we need at least one record in buffer */
232 p = m->op->start(m, &pos);
237 err = m->op->show(m, p);
242 if (unlikely(!m->count)) {
243 p = m->op->next(m, p, &pos);
247 if (m->count < m->size)
252 m->buf = seq_buf_alloc(m->size <<= 1);
257 p = m->op->start(m, &pos);
263 /* they want more? let's try to get some more */
264 while (m->count < size) {
265 size_t offs = m->count;
267 p = m->op->next(m, p, &next);
268 if (!p || IS_ERR(p)) {
272 err = m->op->show(m, p);
273 if (seq_has_overflowed(m) || err) {
275 if (likely(err <= 0))
281 n = min(m->count, size);
282 err = copy_to_user(buf, m->buf, n);
297 m->read_pos += copied;
299 file->f_version = m->version;
300 mutex_unlock(&m->lock);
309 EXPORT_SYMBOL(seq_read);
312 * seq_lseek - ->llseek() method for sequential files.
313 * @file: the file in question
314 * @offset: new position
315 * @whence: 0 for absolute, 1 for relative position
317 * Ready-made ->f_op->llseek()
319 loff_t seq_lseek(struct file *file, loff_t offset, int whence)
321 struct seq_file *m = file->private_data;
322 loff_t retval = -EINVAL;
324 mutex_lock(&m->lock);
325 m->version = file->f_version;
328 offset += file->f_pos;
333 if (offset != m->read_pos) {
334 while ((retval = traverse(m, offset)) == -EAGAIN)
337 /* with extreme prejudice... */
344 m->read_pos = offset;
345 retval = file->f_pos = offset;
348 file->f_pos = offset;
351 file->f_version = m->version;
352 mutex_unlock(&m->lock);
355 EXPORT_SYMBOL(seq_lseek);
358 * seq_release - free the structures associated with sequential file.
359 * @file: file in question
362 * Frees the structures associated with sequential file; can be used
363 * as ->f_op->release() if you don't have private data to destroy.
365 int seq_release(struct inode *inode, struct file *file)
367 struct seq_file *m = file->private_data;
372 EXPORT_SYMBOL(seq_release);
375 * seq_escape - print string into buffer, escaping some characters
378 * @esc: set of characters that need escaping
380 * Puts string into buffer, replacing each occurrence of character from
381 * @esc with usual octal escape.
382 * Use seq_has_overflowed() to check for errors.
384 void seq_escape(struct seq_file *m, const char *s, const char *esc)
387 size_t size = seq_get_buf(m, &buf);
390 ret = string_escape_str(s, buf, size, ESCAPE_OCTAL, esc);
391 seq_commit(m, ret < size ? ret : -1);
393 EXPORT_SYMBOL(seq_escape);
395 void seq_vprintf(struct seq_file *m, const char *f, va_list args)
399 if (m->count < m->size) {
400 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
401 if (m->count + len < m->size) {
408 EXPORT_SYMBOL(seq_vprintf);
410 void seq_printf(struct seq_file *m, const char *f, ...)
415 seq_vprintf(m, f, args);
418 EXPORT_SYMBOL(seq_printf);
421 * mangle_path - mangle and copy path to buffer beginning
423 * @p: beginning of path in above buffer
424 * @esc: set of characters that need escaping
426 * Copy the path from @p to @s, replacing each occurrence of character from
427 * @esc with usual octal escape.
428 * Returns pointer past last written character in @s, or NULL in case of
431 char *mangle_path(char *s, const char *p, const char *esc)
437 } else if (!strchr(esc, c)) {
439 } else if (s + 4 > p) {
443 *s++ = '0' + ((c & 0300) >> 6);
444 *s++ = '0' + ((c & 070) >> 3);
445 *s++ = '0' + (c & 07);
450 EXPORT_SYMBOL(mangle_path);
453 * seq_path - seq_file interface to print a pathname
454 * @m: the seq_file handle
455 * @path: the struct path to print
456 * @esc: set of characters to escape in the output
458 * return the absolute path of 'path', as represented by the
459 * dentry / mnt pair in the path parameter.
461 int seq_path(struct seq_file *m, const struct path *path, const char *esc)
464 size_t size = seq_get_buf(m, &buf);
468 char *p = d_path(path, buf, size);
470 char *end = mangle_path(buf, p, esc);
479 EXPORT_SYMBOL(seq_path);
482 * seq_file_path - seq_file interface to print a pathname of a file
483 * @m: the seq_file handle
484 * @file: the struct file to print
485 * @esc: set of characters to escape in the output
487 * return the absolute path to the file.
489 int seq_file_path(struct seq_file *m, struct file *file, const char *esc)
491 return seq_path(m, &file->f_path, esc);
493 EXPORT_SYMBOL(seq_file_path);
496 * Same as seq_path, but relative to supplied root.
498 int seq_path_root(struct seq_file *m, const struct path *path,
499 const struct path *root, const char *esc)
502 size_t size = seq_get_buf(m, &buf);
503 int res = -ENAMETOOLONG;
508 p = __d_path(path, root, buf, size);
513 char *end = mangle_path(buf, p, esc);
522 return res < 0 && res != -ENAMETOOLONG ? res : 0;
526 * returns the path of the 'dentry' from the root of its filesystem.
528 int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
531 size_t size = seq_get_buf(m, &buf);
535 char *p = dentry_path(dentry, buf, size);
537 char *end = mangle_path(buf, p, esc);
546 EXPORT_SYMBOL(seq_dentry);
548 static void *single_start(struct seq_file *p, loff_t *pos)
550 return NULL + (*pos == 0);
553 static void *single_next(struct seq_file *p, void *v, loff_t *pos)
559 static void single_stop(struct seq_file *p, void *v)
563 int single_open(struct file *file, int (*show)(struct seq_file *, void *),
566 struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL);
570 op->start = single_start;
571 op->next = single_next;
572 op->stop = single_stop;
574 res = seq_open(file, op);
576 ((struct seq_file *)file->private_data)->private = data;
582 EXPORT_SYMBOL(single_open);
584 int single_open_size(struct file *file, int (*show)(struct seq_file *, void *),
585 void *data, size_t size)
587 char *buf = seq_buf_alloc(size);
591 ret = single_open(file, show, data);
596 ((struct seq_file *)file->private_data)->buf = buf;
597 ((struct seq_file *)file->private_data)->size = size;
600 EXPORT_SYMBOL(single_open_size);
602 int single_release(struct inode *inode, struct file *file)
604 const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
605 int res = seq_release(inode, file);
609 EXPORT_SYMBOL(single_release);
611 int seq_release_private(struct inode *inode, struct file *file)
613 struct seq_file *seq = file->private_data;
617 return seq_release(inode, file);
619 EXPORT_SYMBOL(seq_release_private);
621 void *__seq_open_private(struct file *f, const struct seq_operations *ops,
626 struct seq_file *seq;
628 private = kzalloc(psize, GFP_KERNEL);
632 rc = seq_open(f, ops);
636 seq = f->private_data;
637 seq->private = private;
645 EXPORT_SYMBOL(__seq_open_private);
647 int seq_open_private(struct file *filp, const struct seq_operations *ops,
650 return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM;
652 EXPORT_SYMBOL(seq_open_private);
654 void seq_putc(struct seq_file *m, char c)
656 if (m->count >= m->size)
659 m->buf[m->count++] = c;
661 EXPORT_SYMBOL(seq_putc);
663 void seq_puts(struct seq_file *m, const char *s)
667 if (m->count + len >= m->size) {
671 memcpy(m->buf + m->count, s, len);
674 EXPORT_SYMBOL(seq_puts);
677 * A helper routine for putting decimal numbers without rich format of printf().
678 * only 'unsigned long long' is supported.
679 * This routine will put one byte delimiter + number into seq_file.
680 * This routine is very quick when you show lots of numbers.
681 * In usual cases, it will be better to use seq_printf(). It's easier to read.
683 void seq_put_decimal_ull(struct seq_file *m, char delimiter,
684 unsigned long long num)
688 if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
692 m->buf[m->count++] = delimiter;
695 m->buf[m->count++] = num + '0';
699 len = num_to_str(m->buf + m->count, m->size - m->count, num);
708 EXPORT_SYMBOL(seq_put_decimal_ull);
710 void seq_put_decimal_ll(struct seq_file *m, char delimiter, long long num)
713 if (m->count + 3 >= m->size) {
718 m->buf[m->count++] = delimiter;
722 seq_put_decimal_ull(m, delimiter, num);
724 EXPORT_SYMBOL(seq_put_decimal_ll);
727 * seq_write - write arbitrary data to buffer
728 * @seq: seq_file identifying the buffer to which data should be written
729 * @data: data address
730 * @len: number of bytes
732 * Return 0 on success, non-zero otherwise.
734 int seq_write(struct seq_file *seq, const void *data, size_t len)
736 if (seq->count + len < seq->size) {
737 memcpy(seq->buf + seq->count, data, len);
741 seq_set_overflow(seq);
744 EXPORT_SYMBOL(seq_write);
747 * seq_pad - write padding spaces to buffer
748 * @m: seq_file identifying the buffer to which data should be written
749 * @c: the byte to append after padding if non-zero
751 void seq_pad(struct seq_file *m, char c)
753 int size = m->pad_until - m->count;
755 seq_printf(m, "%*s", size, "");
759 EXPORT_SYMBOL(seq_pad);
761 /* A complete analogue of print_hex_dump() */
762 void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,
763 int rowsize, int groupsize, const void *buf, size_t len,
767 int i, linelen, remaining = len;
772 if (rowsize != 16 && rowsize != 32)
775 for (i = 0; i < len && !seq_has_overflowed(m); i += rowsize) {
776 linelen = min(remaining, rowsize);
777 remaining -= rowsize;
779 switch (prefix_type) {
780 case DUMP_PREFIX_ADDRESS:
781 seq_printf(m, "%s%p: ", prefix_str, ptr + i);
783 case DUMP_PREFIX_OFFSET:
784 seq_printf(m, "%s%.8x: ", prefix_str, i);
787 seq_printf(m, "%s", prefix_str);
791 size = seq_get_buf(m, &buffer);
792 ret = hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
793 buffer, size, ascii);
794 seq_commit(m, ret < size ? ret : -1);
799 EXPORT_SYMBOL(seq_hex_dump);
801 struct list_head *seq_list_start(struct list_head *head, loff_t pos)
803 struct list_head *lh;
805 list_for_each(lh, head)
811 EXPORT_SYMBOL(seq_list_start);
813 struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
818 return seq_list_start(head, pos - 1);
820 EXPORT_SYMBOL(seq_list_start_head);
822 struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
824 struct list_head *lh;
826 lh = ((struct list_head *)v)->next;
828 return lh == head ? NULL : lh;
830 EXPORT_SYMBOL(seq_list_next);
833 * seq_hlist_start - start an iteration of a hlist
834 * @head: the head of the hlist
835 * @pos: the start position of the sequence
837 * Called at seq_file->op->start().
839 struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
841 struct hlist_node *node;
843 hlist_for_each(node, head)
848 EXPORT_SYMBOL(seq_hlist_start);
851 * seq_hlist_start_head - start an iteration of a hlist
852 * @head: the head of the hlist
853 * @pos: the start position of the sequence
855 * Called at seq_file->op->start(). Call this function if you want to
856 * print a header at the top of the output.
858 struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
861 return SEQ_START_TOKEN;
863 return seq_hlist_start(head, pos - 1);
865 EXPORT_SYMBOL(seq_hlist_start_head);
868 * seq_hlist_next - move to the next position of the hlist
869 * @v: the current iterator
870 * @head: the head of the hlist
871 * @ppos: the current position
873 * Called at seq_file->op->next().
875 struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
878 struct hlist_node *node = v;
881 if (v == SEQ_START_TOKEN)
886 EXPORT_SYMBOL(seq_hlist_next);
889 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
890 * @head: the head of the hlist
891 * @pos: the start position of the sequence
893 * Called at seq_file->op->start().
895 * This list-traversal primitive may safely run concurrently with
896 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
897 * as long as the traversal is guarded by rcu_read_lock().
899 struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
902 struct hlist_node *node;
904 __hlist_for_each_rcu(node, head)
909 EXPORT_SYMBOL(seq_hlist_start_rcu);
912 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
913 * @head: the head of the hlist
914 * @pos: the start position of the sequence
916 * Called at seq_file->op->start(). Call this function if you want to
917 * print a header at the top of the output.
919 * This list-traversal primitive may safely run concurrently with
920 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
921 * as long as the traversal is guarded by rcu_read_lock().
923 struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
927 return SEQ_START_TOKEN;
929 return seq_hlist_start_rcu(head, pos - 1);
931 EXPORT_SYMBOL(seq_hlist_start_head_rcu);
934 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
935 * @v: the current iterator
936 * @head: the head of the hlist
937 * @ppos: the current position
939 * Called at seq_file->op->next().
941 * This list-traversal primitive may safely run concurrently with
942 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
943 * as long as the traversal is guarded by rcu_read_lock().
945 struct hlist_node *seq_hlist_next_rcu(void *v,
946 struct hlist_head *head,
949 struct hlist_node *node = v;
952 if (v == SEQ_START_TOKEN)
953 return rcu_dereference(head->first);
955 return rcu_dereference(node->next);
957 EXPORT_SYMBOL(seq_hlist_next_rcu);
960 * seq_hlist_start_precpu - start an iteration of a percpu hlist array
961 * @head: pointer to percpu array of struct hlist_heads
962 * @cpu: pointer to cpu "cursor"
963 * @pos: start position of sequence
965 * Called at seq_file->op->start().
968 seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
970 struct hlist_node *node;
972 for_each_possible_cpu(*cpu) {
973 hlist_for_each(node, per_cpu_ptr(head, *cpu)) {
980 EXPORT_SYMBOL(seq_hlist_start_percpu);
983 * seq_hlist_next_percpu - move to the next position of the percpu hlist array
984 * @v: pointer to current hlist_node
985 * @head: pointer to percpu array of struct hlist_heads
986 * @cpu: pointer to cpu "cursor"
987 * @pos: start position of sequence
989 * Called at seq_file->op->next().
992 seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head,
993 int *cpu, loff_t *pos)
995 struct hlist_node *node = v;
1002 for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids;
1003 *cpu = cpumask_next(*cpu, cpu_possible_mask)) {
1004 struct hlist_head *bucket = per_cpu_ptr(head, *cpu);
1006 if (!hlist_empty(bucket))
1007 return bucket->first;
1011 EXPORT_SYMBOL(seq_hlist_next_percpu);