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 * Wrappers around seq_open(e.g. swaps_open) need to be
72 * aware of this. If they set f_version themselves, they
73 * should call seq_open first and then set f_version.
78 * seq_files support lseek() and pread(). They do not implement
79 * write() at all, but we clear FMODE_PWRITE here for historical
82 * If a client of seq_files a) implements file.write() and b) wishes to
83 * support pwrite() then that client will need to implement its own
84 * file.open() which calls seq_open() and then sets FMODE_PWRITE.
86 file->f_mode &= ~FMODE_PWRITE;
89 EXPORT_SYMBOL(seq_open);
91 static int traverse(struct seq_file *m, loff_t offset)
99 m->count = m->from = 0;
104 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
108 p = m->op->start(m, &m->index);
113 error = m->op->show(m, p);
116 if (unlikely(error)) {
120 if (seq_has_overflowed(m))
122 if (pos + m->count > offset) {
123 m->from = offset - pos;
129 p = m->op->next(m, p, &m->index);
140 m->buf = seq_buf_alloc(m->size <<= 1);
141 return !m->buf ? -ENOMEM : -EAGAIN;
145 * seq_read - ->read() method for sequential files.
146 * @file: the file to read from
147 * @buf: the buffer to read to
148 * @size: the maximum number of bytes to read
149 * @ppos: the current position in the file
151 * Ready-made ->f_op->read()
153 ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
155 struct seq_file *m = file->private_data;
161 mutex_lock(&m->lock);
164 * seq_file->op->..m_start/m_stop/m_next may do special actions
165 * or optimisations based on the file->f_version, so we want to
166 * pass the file->f_version to those methods.
168 * seq_file->version is just copy of f_version, and seq_file
169 * methods can treat it simply as file version.
170 * It is copied in first and copied out after all operations.
171 * It is convenient to have it as part of structure to avoid the
172 * need of passing another argument to all the seq_file methods.
174 m->version = file->f_version;
177 * if request is to read from zero offset, reset iterator to first
178 * record as it might have been already advanced by previous requests
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);
222 /* we need at least one record in buffer */
224 p = m->op->start(m, &m->index);
229 err = m->op->show(m, p);
234 if (unlikely(!m->count)) {
235 p = m->op->next(m, p, &m->index);
238 if (m->count < m->size)
243 m->buf = seq_buf_alloc(m->size <<= 1);
247 p = m->op->start(m, &m->index);
253 /* they want more? let's try to get some more */
255 size_t offs = m->count;
256 loff_t pos = m->index;
258 p = m->op->next(m, p, &m->index);
260 /* Buggy ->next function */
262 if (!p || IS_ERR(p)) {
266 if (m->count >= size)
268 err = m->op->show(m, p);
269 if (seq_has_overflowed(m) || err) {
271 if (likely(err <= 0))
276 n = min(m->count, size);
277 err = copy_to_user(buf, m->buf, n);
288 m->read_pos += copied;
290 file->f_version = m->version;
291 mutex_unlock(&m->lock);
300 EXPORT_SYMBOL(seq_read);
303 * seq_lseek - ->llseek() method for sequential files.
304 * @file: the file in question
305 * @offset: new position
306 * @whence: 0 for absolute, 1 for relative position
308 * Ready-made ->f_op->llseek()
310 loff_t seq_lseek(struct file *file, loff_t offset, int whence)
312 struct seq_file *m = file->private_data;
313 loff_t retval = -EINVAL;
315 mutex_lock(&m->lock);
316 m->version = file->f_version;
319 offset += file->f_pos;
325 if (offset != m->read_pos) {
326 while ((retval = traverse(m, offset)) == -EAGAIN)
329 /* with extreme prejudice... */
336 m->read_pos = offset;
337 retval = file->f_pos = offset;
340 file->f_pos = offset;
343 file->f_version = m->version;
344 mutex_unlock(&m->lock);
347 EXPORT_SYMBOL(seq_lseek);
350 * seq_release - free the structures associated with sequential file.
351 * @file: file in question
354 * Frees the structures associated with sequential file; can be used
355 * as ->f_op->release() if you don't have private data to destroy.
357 int seq_release(struct inode *inode, struct file *file)
359 struct seq_file *m = file->private_data;
361 kmem_cache_free(seq_file_cache, m);
364 EXPORT_SYMBOL(seq_release);
367 * seq_escape - print string into buffer, escaping some characters
370 * @esc: set of characters that need escaping
372 * Puts string into buffer, replacing each occurrence of character from
373 * @esc with usual octal escape.
374 * Use seq_has_overflowed() to check for errors.
376 void seq_escape(struct seq_file *m, const char *s, const char *esc)
379 size_t size = seq_get_buf(m, &buf);
382 ret = string_escape_str(s, buf, size, ESCAPE_OCTAL, esc);
383 seq_commit(m, ret < size ? ret : -1);
385 EXPORT_SYMBOL(seq_escape);
387 void seq_vprintf(struct seq_file *m, const char *f, va_list args)
391 if (m->count < m->size) {
392 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
393 if (m->count + len < m->size) {
400 EXPORT_SYMBOL(seq_vprintf);
402 void seq_printf(struct seq_file *m, const char *f, ...)
407 seq_vprintf(m, f, args);
410 EXPORT_SYMBOL(seq_printf);
413 * mangle_path - mangle and copy path to buffer beginning
415 * @p: beginning of path in above buffer
416 * @esc: set of characters that need escaping
418 * Copy the path from @p to @s, replacing each occurrence of character from
419 * @esc with usual octal escape.
420 * Returns pointer past last written character in @s, or NULL in case of
423 char *mangle_path(char *s, const char *p, const char *esc)
429 } else if (!strchr(esc, c)) {
431 } else if (s + 4 > p) {
435 *s++ = '0' + ((c & 0300) >> 6);
436 *s++ = '0' + ((c & 070) >> 3);
437 *s++ = '0' + (c & 07);
442 EXPORT_SYMBOL(mangle_path);
445 * seq_path - seq_file interface to print a pathname
446 * @m: the seq_file handle
447 * @path: the struct path to print
448 * @esc: set of characters to escape in the output
450 * return the absolute path of 'path', as represented by the
451 * dentry / mnt pair in the path parameter.
453 int seq_path(struct seq_file *m, const struct path *path, const char *esc)
456 size_t size = seq_get_buf(m, &buf);
460 char *p = d_path(path, buf, size);
462 char *end = mangle_path(buf, p, esc);
471 EXPORT_SYMBOL(seq_path);
474 * seq_file_path - seq_file interface to print a pathname of a file
475 * @m: the seq_file handle
476 * @file: the struct file to print
477 * @esc: set of characters to escape in the output
479 * return the absolute path to the file.
481 int seq_file_path(struct seq_file *m, struct file *file, const char *esc)
483 return seq_path(m, &file->f_path, esc);
485 EXPORT_SYMBOL(seq_file_path);
488 * Same as seq_path, but relative to supplied root.
490 int seq_path_root(struct seq_file *m, const struct path *path,
491 const struct path *root, const char *esc)
494 size_t size = seq_get_buf(m, &buf);
495 int res = -ENAMETOOLONG;
500 p = __d_path(path, root, buf, size);
505 char *end = mangle_path(buf, p, esc);
514 return res < 0 && res != -ENAMETOOLONG ? res : 0;
518 * returns the path of the 'dentry' from the root of its filesystem.
520 int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
523 size_t size = seq_get_buf(m, &buf);
527 char *p = dentry_path(dentry, buf, size);
529 char *end = mangle_path(buf, p, esc);
538 EXPORT_SYMBOL(seq_dentry);
540 static void *single_start(struct seq_file *p, loff_t *pos)
542 return NULL + (*pos == 0);
545 static void *single_next(struct seq_file *p, void *v, loff_t *pos)
551 static void single_stop(struct seq_file *p, void *v)
555 int single_open(struct file *file, int (*show)(struct seq_file *, void *),
558 struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL_ACCOUNT);
562 op->start = single_start;
563 op->next = single_next;
564 op->stop = single_stop;
566 res = seq_open(file, op);
568 ((struct seq_file *)file->private_data)->private = data;
574 EXPORT_SYMBOL(single_open);
576 int single_open_size(struct file *file, int (*show)(struct seq_file *, void *),
577 void *data, size_t size)
579 char *buf = seq_buf_alloc(size);
583 ret = single_open(file, show, data);
588 ((struct seq_file *)file->private_data)->buf = buf;
589 ((struct seq_file *)file->private_data)->size = size;
592 EXPORT_SYMBOL(single_open_size);
594 int single_release(struct inode *inode, struct file *file)
596 const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
597 int res = seq_release(inode, file);
601 EXPORT_SYMBOL(single_release);
603 int seq_release_private(struct inode *inode, struct file *file)
605 struct seq_file *seq = file->private_data;
609 return seq_release(inode, file);
611 EXPORT_SYMBOL(seq_release_private);
613 void *__seq_open_private(struct file *f, const struct seq_operations *ops,
618 struct seq_file *seq;
620 private = kzalloc(psize, GFP_KERNEL_ACCOUNT);
624 rc = seq_open(f, ops);
628 seq = f->private_data;
629 seq->private = private;
637 EXPORT_SYMBOL(__seq_open_private);
639 int seq_open_private(struct file *filp, const struct seq_operations *ops,
642 return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM;
644 EXPORT_SYMBOL(seq_open_private);
646 void seq_putc(struct seq_file *m, char c)
648 if (m->count >= m->size)
651 m->buf[m->count++] = c;
653 EXPORT_SYMBOL(seq_putc);
655 void seq_puts(struct seq_file *m, const char *s)
659 if (m->count + len >= m->size) {
663 memcpy(m->buf + m->count, s, len);
666 EXPORT_SYMBOL(seq_puts);
669 * A helper routine for putting decimal numbers without rich format of printf().
670 * only 'unsigned long long' is supported.
671 * @m: seq_file identifying the buffer to which data should be written
672 * @delimiter: a string which is printed before the number
674 * @width: a minimum field width
676 * This routine will put strlen(delimiter) + number into seq_filed.
677 * This routine is very quick when you show lots of numbers.
678 * In usual cases, it will be better to use seq_printf(). It's easier to read.
680 void seq_put_decimal_ull_width(struct seq_file *m, const char *delimiter,
681 unsigned long long num, unsigned int width)
685 if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
688 if (delimiter && delimiter[0]) {
689 if (delimiter[1] == 0)
690 seq_putc(m, delimiter[0]);
692 seq_puts(m, delimiter);
698 if (m->count + width >= m->size)
701 len = num_to_str(m->buf + m->count, m->size - m->count, num, width);
712 void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
713 unsigned long long num)
715 return seq_put_decimal_ull_width(m, delimiter, num, 0);
717 EXPORT_SYMBOL(seq_put_decimal_ull);
720 * seq_put_hex_ll - put a number in hexadecimal notation
721 * @m: seq_file identifying the buffer to which data should be written
722 * @delimiter: a string which is printed before the number
724 * @width: a minimum field width
726 * seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "%08llx", v)
728 * This routine is very quick when you show lots of numbers.
729 * In usual cases, it will be better to use seq_printf(). It's easier to read.
731 void seq_put_hex_ll(struct seq_file *m, const char *delimiter,
732 unsigned long long v, unsigned int width)
737 if (delimiter && delimiter[0]) {
738 if (delimiter[1] == 0)
739 seq_putc(m, delimiter[0]);
741 seq_puts(m, delimiter);
744 /* If x is 0, the result of __builtin_clzll is undefined */
748 len = (sizeof(v) * 8 - __builtin_clzll(v) + 3) / 4;
753 if (m->count + len > m->size) {
758 for (i = len - 1; i >= 0; i--) {
759 m->buf[m->count + i] = hex_asc[0xf & v];
765 void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num)
769 if (m->count + 3 >= m->size) /* we'll write 2 bytes at least */
772 if (delimiter && delimiter[0]) {
773 if (delimiter[1] == 0)
774 seq_putc(m, delimiter[0]);
776 seq_puts(m, delimiter);
779 if (m->count + 2 >= m->size)
783 m->buf[m->count++] = '-';
788 m->buf[m->count++] = num + '0';
792 len = num_to_str(m->buf + m->count, m->size - m->count, num, 0);
802 EXPORT_SYMBOL(seq_put_decimal_ll);
805 * seq_write - write arbitrary data to buffer
806 * @seq: seq_file identifying the buffer to which data should be written
807 * @data: data address
808 * @len: number of bytes
810 * Return 0 on success, non-zero otherwise.
812 int seq_write(struct seq_file *seq, const void *data, size_t len)
814 if (seq->count + len < seq->size) {
815 memcpy(seq->buf + seq->count, data, len);
819 seq_set_overflow(seq);
822 EXPORT_SYMBOL(seq_write);
825 * seq_pad - write padding spaces to buffer
826 * @m: seq_file identifying the buffer to which data should be written
827 * @c: the byte to append after padding if non-zero
829 void seq_pad(struct seq_file *m, char c)
831 int size = m->pad_until - m->count;
833 if (size + m->count > m->size) {
837 memset(m->buf + m->count, ' ', size);
843 EXPORT_SYMBOL(seq_pad);
845 /* A complete analogue of print_hex_dump() */
846 void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,
847 int rowsize, int groupsize, const void *buf, size_t len,
851 int i, linelen, remaining = len;
856 if (rowsize != 16 && rowsize != 32)
859 for (i = 0; i < len && !seq_has_overflowed(m); i += rowsize) {
860 linelen = min(remaining, rowsize);
861 remaining -= rowsize;
863 switch (prefix_type) {
864 case DUMP_PREFIX_ADDRESS:
865 seq_printf(m, "%s%p: ", prefix_str, ptr + i);
867 case DUMP_PREFIX_OFFSET:
868 seq_printf(m, "%s%.8x: ", prefix_str, i);
871 seq_printf(m, "%s", prefix_str);
875 size = seq_get_buf(m, &buffer);
876 ret = hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
877 buffer, size, ascii);
878 seq_commit(m, ret < size ? ret : -1);
883 EXPORT_SYMBOL(seq_hex_dump);
885 struct list_head *seq_list_start(struct list_head *head, loff_t pos)
887 struct list_head *lh;
889 list_for_each(lh, head)
895 EXPORT_SYMBOL(seq_list_start);
897 struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
902 return seq_list_start(head, pos - 1);
904 EXPORT_SYMBOL(seq_list_start_head);
906 struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
908 struct list_head *lh;
910 lh = ((struct list_head *)v)->next;
912 return lh == head ? NULL : lh;
914 EXPORT_SYMBOL(seq_list_next);
917 * seq_hlist_start - start an iteration of a hlist
918 * @head: the head of the hlist
919 * @pos: the start position of the sequence
921 * Called at seq_file->op->start().
923 struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
925 struct hlist_node *node;
927 hlist_for_each(node, head)
932 EXPORT_SYMBOL(seq_hlist_start);
935 * seq_hlist_start_head - start an iteration of a hlist
936 * @head: the head of the hlist
937 * @pos: the start position of the sequence
939 * Called at seq_file->op->start(). Call this function if you want to
940 * print a header at the top of the output.
942 struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
945 return SEQ_START_TOKEN;
947 return seq_hlist_start(head, pos - 1);
949 EXPORT_SYMBOL(seq_hlist_start_head);
952 * seq_hlist_next - move to the next position of the hlist
953 * @v: the current iterator
954 * @head: the head of the hlist
955 * @ppos: the current position
957 * Called at seq_file->op->next().
959 struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
962 struct hlist_node *node = v;
965 if (v == SEQ_START_TOKEN)
970 EXPORT_SYMBOL(seq_hlist_next);
973 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
974 * @head: the head of the hlist
975 * @pos: the start position of the sequence
977 * Called at seq_file->op->start().
979 * This list-traversal primitive may safely run concurrently with
980 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
981 * as long as the traversal is guarded by rcu_read_lock().
983 struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
986 struct hlist_node *node;
988 __hlist_for_each_rcu(node, head)
993 EXPORT_SYMBOL(seq_hlist_start_rcu);
996 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
997 * @head: the head of the hlist
998 * @pos: the start position of the sequence
1000 * Called at seq_file->op->start(). Call this function if you want to
1001 * print a header at the top of the output.
1003 * This list-traversal primitive may safely run concurrently with
1004 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1005 * as long as the traversal is guarded by rcu_read_lock().
1007 struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
1011 return SEQ_START_TOKEN;
1013 return seq_hlist_start_rcu(head, pos - 1);
1015 EXPORT_SYMBOL(seq_hlist_start_head_rcu);
1018 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
1019 * @v: the current iterator
1020 * @head: the head of the hlist
1021 * @ppos: the current position
1023 * Called at seq_file->op->next().
1025 * This list-traversal primitive may safely run concurrently with
1026 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1027 * as long as the traversal is guarded by rcu_read_lock().
1029 struct hlist_node *seq_hlist_next_rcu(void *v,
1030 struct hlist_head *head,
1033 struct hlist_node *node = v;
1036 if (v == SEQ_START_TOKEN)
1037 return rcu_dereference(head->first);
1039 return rcu_dereference(node->next);
1041 EXPORT_SYMBOL(seq_hlist_next_rcu);
1044 * seq_hlist_start_precpu - start an iteration of a percpu hlist array
1045 * @head: pointer to percpu array of struct hlist_heads
1046 * @cpu: pointer to cpu "cursor"
1047 * @pos: start position of sequence
1049 * Called at seq_file->op->start().
1052 seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
1054 struct hlist_node *node;
1056 for_each_possible_cpu(*cpu) {
1057 hlist_for_each(node, per_cpu_ptr(head, *cpu)) {
1064 EXPORT_SYMBOL(seq_hlist_start_percpu);
1067 * seq_hlist_next_percpu - move to the next position of the percpu hlist array
1068 * @v: pointer to current hlist_node
1069 * @head: pointer to percpu array of struct hlist_heads
1070 * @cpu: pointer to cpu "cursor"
1071 * @pos: start position of sequence
1073 * Called at seq_file->op->next().
1076 seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head,
1077 int *cpu, loff_t *pos)
1079 struct hlist_node *node = v;
1086 for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids;
1087 *cpu = cpumask_next(*cpu, cpu_possible_mask)) {
1088 struct hlist_head *bucket = per_cpu_ptr(head, *cpu);
1090 if (!hlist_empty(bucket))
1091 return bucket->first;
1095 EXPORT_SYMBOL(seq_hlist_next_percpu);
1097 void __init seq_file_init(void)
1099 seq_file_cache = KMEM_CACHE(seq_file, SLAB_ACCOUNT|SLAB_PANIC);