1 // SPDX-License-Identifier: GPL-2.0
5 * helper functions for making synthetic files from sequences of records.
6 * initial implementation -- AV, Oct 2001.
9 #include <linux/cache.h>
11 #include <linux/export.h>
12 #include <linux/seq_file.h>
13 #include <linux/vmalloc.h>
14 #include <linux/slab.h>
15 #include <linux/cred.h>
17 #include <linux/printk.h>
18 #include <linux/string_helpers.h>
20 #include <linux/uaccess.h>
23 static struct kmem_cache *seq_file_cache __ro_after_init;
25 static void seq_set_overflow(struct seq_file *m)
30 static void *seq_buf_alloc(unsigned long size)
32 return kvmalloc(size, GFP_KERNEL_ACCOUNT);
36 * seq_open - initialize sequential file
37 * @file: file we initialize
38 * @op: method table describing the sequence
40 * seq_open() sets @file, associating it with a sequence described
41 * by @op. @op->start() sets the iterator up and returns the first
42 * element of sequence. @op->stop() shuts it down. @op->next()
43 * returns the next element of sequence. @op->show() prints element
44 * into the buffer. In case of error ->start() and ->next() return
45 * ERR_PTR(error). In the end of sequence they return %NULL. ->show()
46 * returns 0 in case of success and negative number in case of error.
47 * Returning SEQ_SKIP means "discard this element and move on".
48 * Note: seq_open() will allocate a struct seq_file and store its
49 * pointer in @file->private_data. This pointer should not be modified.
51 int seq_open(struct file *file, const struct seq_operations *op)
55 WARN_ON(file->private_data);
57 p = kmem_cache_zalloc(seq_file_cache, GFP_KERNEL);
61 file->private_data = p;
66 // No refcounting: the lifetime of 'p' is constrained
67 // to the lifetime of the file.
71 * seq_files support lseek() and pread(). They do not implement
72 * write() at all, but we clear FMODE_PWRITE here for historical
75 * If a client of seq_files a) implements file.write() and b) wishes to
76 * support pwrite() then that client will need to implement its own
77 * file.open() which calls seq_open() and then sets FMODE_PWRITE.
79 file->f_mode &= ~FMODE_PWRITE;
82 EXPORT_SYMBOL(seq_open);
84 static int traverse(struct seq_file *m, loff_t offset)
91 m->count = m->from = 0;
96 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
100 p = m->op->start(m, &m->index);
105 error = m->op->show(m, p);
108 if (unlikely(error)) {
112 if (seq_has_overflowed(m))
114 p = m->op->next(m, p, &m->index);
115 if (pos + m->count > offset) {
116 m->from = offset - pos;
132 m->buf = seq_buf_alloc(m->size <<= 1);
133 return !m->buf ? -ENOMEM : -EAGAIN;
137 * seq_read - ->read() method for sequential files.
138 * @file: the file to read from
139 * @buf: the buffer to read to
140 * @size: the maximum number of bytes to read
141 * @ppos: the current position in the file
143 * Ready-made ->f_op->read()
145 ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
147 struct seq_file *m = file->private_data;
153 mutex_lock(&m->lock);
156 * if request is to read from zero offset, reset iterator to first
157 * record as it might have been already advanced by previous requests
164 /* Don't assume *ppos is where we left it */
165 if (unlikely(*ppos != m->read_pos)) {
166 while ((err = traverse(m, *ppos)) == -EAGAIN)
169 /* With prejudice... */
179 /* grab buffer if we didn't have one */
181 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
185 /* if not empty - flush it first */
187 n = min(m->count, size);
188 err = copy_to_user(buf, m->buf + m->from, n);
199 /* we need at least one record in buffer */
201 p = m->op->start(m, &m->index);
206 err = m->op->show(m, p);
211 if (unlikely(!m->count)) {
212 p = m->op->next(m, p, &m->index);
215 if (m->count < m->size)
220 m->buf = seq_buf_alloc(m->size <<= 1);
223 p = m->op->start(m, &m->index);
229 /* they want more? let's try to get some more */
231 size_t offs = m->count;
232 loff_t pos = m->index;
234 p = m->op->next(m, p, &m->index);
236 /* Buggy ->next function */
238 if (!p || IS_ERR(p)) {
242 if (m->count >= size)
244 err = m->op->show(m, p);
245 if (seq_has_overflowed(m) || err) {
247 if (likely(err <= 0))
252 n = min(m->count, size);
253 err = copy_to_user(buf, m->buf, n);
264 m->read_pos += copied;
266 mutex_unlock(&m->lock);
275 EXPORT_SYMBOL(seq_read);
278 * seq_lseek - ->llseek() method for sequential files.
279 * @file: the file in question
280 * @offset: new position
281 * @whence: 0 for absolute, 1 for relative position
283 * Ready-made ->f_op->llseek()
285 loff_t seq_lseek(struct file *file, loff_t offset, int whence)
287 struct seq_file *m = file->private_data;
288 loff_t retval = -EINVAL;
290 mutex_lock(&m->lock);
293 offset += file->f_pos;
299 if (offset != m->read_pos) {
300 while ((retval = traverse(m, offset)) == -EAGAIN)
303 /* with extreme prejudice... */
309 m->read_pos = offset;
310 retval = file->f_pos = offset;
313 file->f_pos = offset;
316 mutex_unlock(&m->lock);
319 EXPORT_SYMBOL(seq_lseek);
322 * seq_release - free the structures associated with sequential file.
323 * @file: file in question
326 * Frees the structures associated with sequential file; can be used
327 * as ->f_op->release() if you don't have private data to destroy.
329 int seq_release(struct inode *inode, struct file *file)
331 struct seq_file *m = file->private_data;
333 kmem_cache_free(seq_file_cache, m);
336 EXPORT_SYMBOL(seq_release);
339 * seq_escape - print string into buffer, escaping some characters
342 * @esc: set of characters that need escaping
344 * Puts string into buffer, replacing each occurrence of character from
345 * @esc with usual octal escape.
346 * Use seq_has_overflowed() to check for errors.
348 void seq_escape(struct seq_file *m, const char *s, const char *esc)
351 size_t size = seq_get_buf(m, &buf);
354 ret = string_escape_str(s, buf, size, ESCAPE_OCTAL, esc);
355 seq_commit(m, ret < size ? ret : -1);
357 EXPORT_SYMBOL(seq_escape);
359 void seq_escape_mem_ascii(struct seq_file *m, const char *src, size_t isz)
362 size_t size = seq_get_buf(m, &buf);
365 ret = string_escape_mem_ascii(src, isz, buf, size);
366 seq_commit(m, ret < size ? ret : -1);
368 EXPORT_SYMBOL(seq_escape_mem_ascii);
370 void seq_vprintf(struct seq_file *m, const char *f, va_list args)
374 if (m->count < m->size) {
375 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
376 if (m->count + len < m->size) {
383 EXPORT_SYMBOL(seq_vprintf);
385 void seq_printf(struct seq_file *m, const char *f, ...)
390 seq_vprintf(m, f, args);
393 EXPORT_SYMBOL(seq_printf);
396 * mangle_path - mangle and copy path to buffer beginning
398 * @p: beginning of path in above buffer
399 * @esc: set of characters that need escaping
401 * Copy the path from @p to @s, replacing each occurrence of character from
402 * @esc with usual octal escape.
403 * Returns pointer past last written character in @s, or NULL in case of
406 char *mangle_path(char *s, const char *p, const char *esc)
412 } else if (!strchr(esc, c)) {
414 } else if (s + 4 > p) {
418 *s++ = '0' + ((c & 0300) >> 6);
419 *s++ = '0' + ((c & 070) >> 3);
420 *s++ = '0' + (c & 07);
425 EXPORT_SYMBOL(mangle_path);
428 * seq_path - seq_file interface to print a pathname
429 * @m: the seq_file handle
430 * @path: the struct path to print
431 * @esc: set of characters to escape in the output
433 * return the absolute path of 'path', as represented by the
434 * dentry / mnt pair in the path parameter.
436 int seq_path(struct seq_file *m, const struct path *path, const char *esc)
439 size_t size = seq_get_buf(m, &buf);
443 char *p = d_path(path, buf, size);
445 char *end = mangle_path(buf, p, esc);
454 EXPORT_SYMBOL(seq_path);
457 * seq_file_path - seq_file interface to print a pathname of a file
458 * @m: the seq_file handle
459 * @file: the struct file to print
460 * @esc: set of characters to escape in the output
462 * return the absolute path to the file.
464 int seq_file_path(struct seq_file *m, struct file *file, const char *esc)
466 return seq_path(m, &file->f_path, esc);
468 EXPORT_SYMBOL(seq_file_path);
471 * Same as seq_path, but relative to supplied root.
473 int seq_path_root(struct seq_file *m, const struct path *path,
474 const struct path *root, const char *esc)
477 size_t size = seq_get_buf(m, &buf);
478 int res = -ENAMETOOLONG;
483 p = __d_path(path, root, buf, size);
488 char *end = mangle_path(buf, p, esc);
497 return res < 0 && res != -ENAMETOOLONG ? res : 0;
501 * returns the path of the 'dentry' from the root of its filesystem.
503 int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
506 size_t size = seq_get_buf(m, &buf);
510 char *p = dentry_path(dentry, buf, size);
512 char *end = mangle_path(buf, p, esc);
521 EXPORT_SYMBOL(seq_dentry);
523 static void *single_start(struct seq_file *p, loff_t *pos)
525 return NULL + (*pos == 0);
528 static void *single_next(struct seq_file *p, void *v, loff_t *pos)
534 static void single_stop(struct seq_file *p, void *v)
538 int single_open(struct file *file, int (*show)(struct seq_file *, void *),
541 struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL_ACCOUNT);
545 op->start = single_start;
546 op->next = single_next;
547 op->stop = single_stop;
549 res = seq_open(file, op);
551 ((struct seq_file *)file->private_data)->private = data;
557 EXPORT_SYMBOL(single_open);
559 int single_open_size(struct file *file, int (*show)(struct seq_file *, void *),
560 void *data, size_t size)
562 char *buf = seq_buf_alloc(size);
566 ret = single_open(file, show, data);
571 ((struct seq_file *)file->private_data)->buf = buf;
572 ((struct seq_file *)file->private_data)->size = size;
575 EXPORT_SYMBOL(single_open_size);
577 int single_release(struct inode *inode, struct file *file)
579 const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
580 int res = seq_release(inode, file);
584 EXPORT_SYMBOL(single_release);
586 int seq_release_private(struct inode *inode, struct file *file)
588 struct seq_file *seq = file->private_data;
592 return seq_release(inode, file);
594 EXPORT_SYMBOL(seq_release_private);
596 void *__seq_open_private(struct file *f, const struct seq_operations *ops,
601 struct seq_file *seq;
603 private = kzalloc(psize, GFP_KERNEL_ACCOUNT);
607 rc = seq_open(f, ops);
611 seq = f->private_data;
612 seq->private = private;
620 EXPORT_SYMBOL(__seq_open_private);
622 int seq_open_private(struct file *filp, const struct seq_operations *ops,
625 return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM;
627 EXPORT_SYMBOL(seq_open_private);
629 void seq_putc(struct seq_file *m, char c)
631 if (m->count >= m->size)
634 m->buf[m->count++] = c;
636 EXPORT_SYMBOL(seq_putc);
638 void seq_puts(struct seq_file *m, const char *s)
642 if (m->count + len >= m->size) {
646 memcpy(m->buf + m->count, s, len);
649 EXPORT_SYMBOL(seq_puts);
652 * A helper routine for putting decimal numbers without rich format of printf().
653 * only 'unsigned long long' is supported.
654 * @m: seq_file identifying the buffer to which data should be written
655 * @delimiter: a string which is printed before the number
657 * @width: a minimum field width
659 * This routine will put strlen(delimiter) + number into seq_filed.
660 * This routine is very quick when you show lots of numbers.
661 * In usual cases, it will be better to use seq_printf(). It's easier to read.
663 void seq_put_decimal_ull_width(struct seq_file *m, const char *delimiter,
664 unsigned long long num, unsigned int width)
668 if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
671 if (delimiter && delimiter[0]) {
672 if (delimiter[1] == 0)
673 seq_putc(m, delimiter[0]);
675 seq_puts(m, delimiter);
681 if (m->count + width >= m->size)
684 len = num_to_str(m->buf + m->count, m->size - m->count, num, width);
695 void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
696 unsigned long long num)
698 return seq_put_decimal_ull_width(m, delimiter, num, 0);
700 EXPORT_SYMBOL(seq_put_decimal_ull);
703 * seq_put_hex_ll - put a number in hexadecimal notation
704 * @m: seq_file identifying the buffer to which data should be written
705 * @delimiter: a string which is printed before the number
707 * @width: a minimum field width
709 * seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "%08llx", v)
711 * This routine is very quick when you show lots of numbers.
712 * In usual cases, it will be better to use seq_printf(). It's easier to read.
714 void seq_put_hex_ll(struct seq_file *m, const char *delimiter,
715 unsigned long long v, unsigned int width)
720 if (delimiter && delimiter[0]) {
721 if (delimiter[1] == 0)
722 seq_putc(m, delimiter[0]);
724 seq_puts(m, delimiter);
727 /* If x is 0, the result of __builtin_clzll is undefined */
731 len = (sizeof(v) * 8 - __builtin_clzll(v) + 3) / 4;
736 if (m->count + len > m->size) {
741 for (i = len - 1; i >= 0; i--) {
742 m->buf[m->count + i] = hex_asc[0xf & v];
748 void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num)
752 if (m->count + 3 >= m->size) /* we'll write 2 bytes at least */
755 if (delimiter && delimiter[0]) {
756 if (delimiter[1] == 0)
757 seq_putc(m, delimiter[0]);
759 seq_puts(m, delimiter);
762 if (m->count + 2 >= m->size)
766 m->buf[m->count++] = '-';
771 m->buf[m->count++] = num + '0';
775 len = num_to_str(m->buf + m->count, m->size - m->count, num, 0);
785 EXPORT_SYMBOL(seq_put_decimal_ll);
788 * seq_write - write arbitrary data to buffer
789 * @seq: seq_file identifying the buffer to which data should be written
790 * @data: data address
791 * @len: number of bytes
793 * Return 0 on success, non-zero otherwise.
795 int seq_write(struct seq_file *seq, const void *data, size_t len)
797 if (seq->count + len < seq->size) {
798 memcpy(seq->buf + seq->count, data, len);
802 seq_set_overflow(seq);
805 EXPORT_SYMBOL(seq_write);
808 * seq_pad - write padding spaces to buffer
809 * @m: seq_file identifying the buffer to which data should be written
810 * @c: the byte to append after padding if non-zero
812 void seq_pad(struct seq_file *m, char c)
814 int size = m->pad_until - m->count;
816 if (size + m->count > m->size) {
820 memset(m->buf + m->count, ' ', size);
826 EXPORT_SYMBOL(seq_pad);
828 /* A complete analogue of print_hex_dump() */
829 void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,
830 int rowsize, int groupsize, const void *buf, size_t len,
834 int i, linelen, remaining = len;
839 if (rowsize != 16 && rowsize != 32)
842 for (i = 0; i < len && !seq_has_overflowed(m); i += rowsize) {
843 linelen = min(remaining, rowsize);
844 remaining -= rowsize;
846 switch (prefix_type) {
847 case DUMP_PREFIX_ADDRESS:
848 seq_printf(m, "%s%p: ", prefix_str, ptr + i);
850 case DUMP_PREFIX_OFFSET:
851 seq_printf(m, "%s%.8x: ", prefix_str, i);
854 seq_printf(m, "%s", prefix_str);
858 size = seq_get_buf(m, &buffer);
859 ret = hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
860 buffer, size, ascii);
861 seq_commit(m, ret < size ? ret : -1);
866 EXPORT_SYMBOL(seq_hex_dump);
868 struct list_head *seq_list_start(struct list_head *head, loff_t pos)
870 struct list_head *lh;
872 list_for_each(lh, head)
878 EXPORT_SYMBOL(seq_list_start);
880 struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
885 return seq_list_start(head, pos - 1);
887 EXPORT_SYMBOL(seq_list_start_head);
889 struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
891 struct list_head *lh;
893 lh = ((struct list_head *)v)->next;
895 return lh == head ? NULL : lh;
897 EXPORT_SYMBOL(seq_list_next);
900 * seq_hlist_start - start an iteration of a hlist
901 * @head: the head of the hlist
902 * @pos: the start position of the sequence
904 * Called at seq_file->op->start().
906 struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
908 struct hlist_node *node;
910 hlist_for_each(node, head)
915 EXPORT_SYMBOL(seq_hlist_start);
918 * seq_hlist_start_head - start an iteration of a hlist
919 * @head: the head of the hlist
920 * @pos: the start position of the sequence
922 * Called at seq_file->op->start(). Call this function if you want to
923 * print a header at the top of the output.
925 struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
928 return SEQ_START_TOKEN;
930 return seq_hlist_start(head, pos - 1);
932 EXPORT_SYMBOL(seq_hlist_start_head);
935 * seq_hlist_next - move to the next position of the hlist
936 * @v: the current iterator
937 * @head: the head of the hlist
938 * @ppos: the current position
940 * Called at seq_file->op->next().
942 struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
945 struct hlist_node *node = v;
948 if (v == SEQ_START_TOKEN)
953 EXPORT_SYMBOL(seq_hlist_next);
956 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
957 * @head: the head of the hlist
958 * @pos: the start position of the sequence
960 * Called at seq_file->op->start().
962 * This list-traversal primitive may safely run concurrently with
963 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
964 * as long as the traversal is guarded by rcu_read_lock().
966 struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
969 struct hlist_node *node;
971 __hlist_for_each_rcu(node, head)
976 EXPORT_SYMBOL(seq_hlist_start_rcu);
979 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
980 * @head: the head of the hlist
981 * @pos: the start position of the sequence
983 * Called at seq_file->op->start(). Call this function if you want to
984 * print a header at the top of the output.
986 * This list-traversal primitive may safely run concurrently with
987 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
988 * as long as the traversal is guarded by rcu_read_lock().
990 struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
994 return SEQ_START_TOKEN;
996 return seq_hlist_start_rcu(head, pos - 1);
998 EXPORT_SYMBOL(seq_hlist_start_head_rcu);
1001 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
1002 * @v: the current iterator
1003 * @head: the head of the hlist
1004 * @ppos: the current position
1006 * Called at seq_file->op->next().
1008 * This list-traversal primitive may safely run concurrently with
1009 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1010 * as long as the traversal is guarded by rcu_read_lock().
1012 struct hlist_node *seq_hlist_next_rcu(void *v,
1013 struct hlist_head *head,
1016 struct hlist_node *node = v;
1019 if (v == SEQ_START_TOKEN)
1020 return rcu_dereference(head->first);
1022 return rcu_dereference(node->next);
1024 EXPORT_SYMBOL(seq_hlist_next_rcu);
1027 * seq_hlist_start_precpu - start an iteration of a percpu hlist array
1028 * @head: pointer to percpu array of struct hlist_heads
1029 * @cpu: pointer to cpu "cursor"
1030 * @pos: start position of sequence
1032 * Called at seq_file->op->start().
1035 seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
1037 struct hlist_node *node;
1039 for_each_possible_cpu(*cpu) {
1040 hlist_for_each(node, per_cpu_ptr(head, *cpu)) {
1047 EXPORT_SYMBOL(seq_hlist_start_percpu);
1050 * seq_hlist_next_percpu - move to the next position of the percpu hlist array
1051 * @v: pointer to current hlist_node
1052 * @head: pointer to percpu array of struct hlist_heads
1053 * @cpu: pointer to cpu "cursor"
1054 * @pos: start position of sequence
1056 * Called at seq_file->op->next().
1059 seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head,
1060 int *cpu, loff_t *pos)
1062 struct hlist_node *node = v;
1069 for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids;
1070 *cpu = cpumask_next(*cpu, cpu_possible_mask)) {
1071 struct hlist_head *bucket = per_cpu_ptr(head, *cpu);
1073 if (!hlist_empty(bucket))
1074 return bucket->first;
1078 EXPORT_SYMBOL(seq_hlist_next_percpu);
1080 void __init seq_file_init(void)
1082 seq_file_cache = KMEM_CACHE(seq_file, SLAB_ACCOUNT|SLAB_PANIC);