// SPDX-License-Identifier: GPL-2.0 /* * linux/fs/seq_file.c * * helper functions for making synthetic files from sequences of records. * initial implementation -- AV, Oct 2001.
*/
staticvoid *seq_buf_alloc(unsignedlong size)
{ if (unlikely(size > MAX_RW_COUNT)) return NULL;
return kvmalloc(size, GFP_KERNEL_ACCOUNT);
}
/** * seq_open - initialize sequential file * @file: file we initialize * @op: method table describing the sequence * * seq_open() sets @file, associating it with a sequence described * by @op. @op->start() sets the iterator up and returns the first * element of sequence. @op->stop() shuts it down. @op->next() * returns the next element of sequence. @op->show() prints element * into the buffer. In case of error ->start() and ->next() return * ERR_PTR(error). In the end of sequence they return %NULL. ->show() * returns 0 in case of success and negative number in case of error. * Returning SEQ_SKIP means "discard this element and move on". * Note: seq_open() will allocate a struct seq_file and store its * pointer in @file->private_data. This pointer should not be modified.
*/ int seq_open(struct file *file, conststruct seq_operations *op)
{ struct seq_file *p;
WARN_ON(file->private_data);
p = kmem_cache_zalloc(seq_file_cache, GFP_KERNEL); if (!p) return -ENOMEM;
file->private_data = p;
mutex_init(&p->lock);
p->op = op;
// No refcounting: the lifetime of 'p' is constrained // to the lifetime of the file.
p->file = file;
/* * seq_files support lseek() and pread(). They do not implement * write() at all, but we clear FMODE_PWRITE here for historical * reasons. * * If a client of seq_files a) implements file.write() and b) wishes to * support pwrite() then that client will need to implement its own * file.open() which calls seq_open() and then sets FMODE_PWRITE.
*/
file->f_mode &= ~FMODE_PWRITE; return 0;
}
EXPORT_SYMBOL(seq_open);
/** * seq_read - ->read() method for sequential files. * @file: the file to read from * @buf: the buffer to read to * @size: the maximum number of bytes to read * @ppos: the current position in the file * * Ready-made ->f_op->read()
*/
ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{ struct iovec iov = { .iov_base = buf, .iov_len = size}; struct kiocb kiocb; struct iov_iter iter;
ssize_t ret;
/* * if request is to read from zero offset, reset iterator to first * record as it might have been already advanced by previous requests
*/ if (iocb->ki_pos == 0) {
m->index = 0;
m->count = 0;
}
/* Don't assume ki_pos is where we left it */ if (unlikely(iocb->ki_pos != m->read_pos)) { while ((err = traverse(m, iocb->ki_pos)) == -EAGAIN)
; if (err) { /* With prejudice... */
m->read_pos = 0;
m->index = 0;
m->count = 0; goto Done;
} else {
m->read_pos = iocb->ki_pos;
}
}
/* grab buffer if we didn't have one */ if (!m->buf) {
m->buf = seq_buf_alloc(m->size = PAGE_SIZE); if (!m->buf) goto Enomem;
} // something left in the buffer - copy it out first if (m->count) {
n = copy_to_iter(m->buf + m->from, m->count, iter);
m->count -= n;
m->from += n;
copied += n; if (m->count) // hadn't managed to copy everything goto Done;
} // get a non-empty record in the buffer
m->from = 0;
p = m->op->start(m, &m->index); while (1) {
err = PTR_ERR(p); if (!p || IS_ERR(p)) // EOF or an error break;
err = m->op->show(m, p); if (err < 0) // hard error break; if (unlikely(err)) // ->show() says "skip it"
m->count = 0; if (unlikely(!m->count)) { // empty record
p = m->op->next(m, p, &m->index); continue;
} if (!seq_has_overflowed(m)) // got it goto Fill; // need a bigger buffer
m->op->stop(m, p);
kvfree(m->buf);
m->count = 0;
m->buf = seq_buf_alloc(m->size <<= 1); if (!m->buf) goto Enomem;
p = m->op->start(m, &m->index);
} // EOF or an error
m->op->stop(m, p);
m->count = 0; goto Done;
Fill: // one non-empty record is in the buffer; if they want more, // try to fit more in, but in any case we need to advance // the iterator once for every record shown. while (1) {
size_t offs = m->count;
loff_t pos = m->index;
p = m->op->next(m, p, &m->index); if (pos == m->index) {
pr_info_ratelimited("buggy .next function %ps did not update position index\n",
m->op->next);
m->index++;
} if (!p || IS_ERR(p)) // no next record for us break; if (m->count >= iov_iter_count(iter)) break;
err = m->op->show(m, p); if (err > 0) { // ->show() says "skip it"
m->count = offs;
} elseif (err || seq_has_overflowed(m)) {
m->count = offs; break;
}
}
m->op->stop(m, p);
n = copy_to_iter(m->buf, m->count, iter);
copied += n;
m->count -= n;
m->from = n;
Done: if (unlikely(!copied)) {
copied = m->count ? -EFAULT : err;
} else {
iocb->ki_pos += copied;
m->read_pos += copied;
}
mutex_unlock(&m->lock); return copied;
Enomem:
err = -ENOMEM; goto Done;
}
EXPORT_SYMBOL(seq_read_iter);
/** * seq_lseek - ->llseek() method for sequential files. * @file: the file in question * @offset: new position * @whence: 0 for absolute, 1 for relative position * * Ready-made ->f_op->llseek()
*/
loff_t seq_lseek(struct file *file, loff_t offset, int whence)
{ struct seq_file *m = file->private_data;
loff_t retval = -EINVAL;
/** * seq_release - free the structures associated with sequential file. * @inode: its inode * @file: file in question * * Frees the structures associated with sequential file; can be used * as ->f_op->release() if you don't have private data to destroy.
*/ int seq_release(struct inode *inode, struct file *file)
{ struct seq_file *m = file->private_data;
kvfree(m->buf);
kmem_cache_free(seq_file_cache, m); return 0;
}
EXPORT_SYMBOL(seq_release);
/** * seq_escape_mem - print data into buffer, escaping some characters * @m: target buffer * @src: source buffer * @len: size of source buffer * @flags: flags to pass to string_escape_mem() * @esc: set of characters that need escaping * * Puts data into buffer, replacing each occurrence of character from * given class (defined by @flags and @esc) with printable escaped sequence. * * Use seq_has_overflowed() to check for errors.
*/ void seq_escape_mem(struct seq_file *m, constchar *src, size_t len, unsignedint flags, constchar *esc)
{ char *buf;
size_t size = seq_get_buf(m, &buf); int ret;
ret = string_escape_mem(src, len, buf, size, flags, esc);
seq_commit(m, ret < size ? ret : -1);
}
EXPORT_SYMBOL(seq_escape_mem);
if (m->count < m->size) {
len = bstr_printf(m->buf + m->count, m->size - m->count, f,
binary); if (m->count + len < m->size) {
m->count += len; return;
}
}
seq_set_overflow(m);
}
EXPORT_SYMBOL(seq_bprintf); #endif/* CONFIG_BINARY_PRINTF */
/** * mangle_path - mangle and copy path to buffer beginning * @s: buffer start * @p: beginning of path in above buffer * @esc: set of characters that need escaping * * Copy the path from @p to @s, replacing each occurrence of character from * @esc with usual octal escape. * Returns pointer past last written character in @s, or NULL in case of * failure.
*/ char *mangle_path(char *s, constchar *p, constchar *esc)
{ while (s <= p) { char c = *p++; if (!c) { return s;
} elseif (!strchr(esc, c)) {
*s++ = c;
} elseif (s + 4 > p) { break;
} else {
*s++ = '\\';
*s++ = '0' + ((c & 0300) >> 6);
*s++ = '0' + ((c & 070) >> 3);
*s++ = '0' + (c & 07);
}
} return NULL;
}
EXPORT_SYMBOL(mangle_path);
/** * seq_path - seq_file interface to print a pathname * @m: the seq_file handle * @path: the struct path to print * @esc: set of characters to escape in the output * * return the absolute path of 'path', as represented by the * dentry / mnt pair in the path parameter.
*/ int seq_path(struct seq_file *m, conststruct path *path, constchar *esc)
{ char *buf;
size_t size = seq_get_buf(m, &buf); int res = -1;
if (size) { char *p = d_path(path, buf, size); if (!IS_ERR(p)) { char *end = mangle_path(buf, p, esc); if (end)
res = end - buf;
}
}
seq_commit(m, res);
return res;
}
EXPORT_SYMBOL(seq_path);
/** * seq_file_path - seq_file interface to print a pathname of a file * @m: the seq_file handle * @file: the struct file to print * @esc: set of characters to escape in the output * * return the absolute path to the file.
*/ int seq_file_path(struct seq_file *m, struct file *file, constchar *esc)
{ return seq_path(m, &file->f_path, esc);
}
EXPORT_SYMBOL(seq_file_path);
/* * Same as seq_path, but relative to supplied root.
*/ int seq_path_root(struct seq_file *m, conststruct path *path, conststruct path *root, constchar *esc)
{ char *buf;
size_t size = seq_get_buf(m, &buf); int res = -ENAMETOOLONG;
if (size) { char *p;
p = __d_path(path, root, buf, size); if (!p) return SEQ_SKIP;
res = PTR_ERR(p); if (!IS_ERR(p)) { char *end = mangle_path(buf, p, esc); if (end)
res = end - buf; else
res = -ENAMETOOLONG;
}
}
seq_commit(m, res);
return res < 0 && res != -ENAMETOOLONG ? res : 0;
}
/* * returns the path of the 'dentry' from the root of its filesystem.
*/ int seq_dentry(struct seq_file *m, struct dentry *dentry, constchar *esc)
{ char *buf;
size_t size = seq_get_buf(m, &buf); int res = -1;
if (size) { char *p = dentry_path(dentry, buf, size); if (!IS_ERR(p)) { char *end = mangle_path(buf, p, esc); if (end)
res = end - buf;
}
}
seq_commit(m, res);
/** * seq_put_decimal_ull_width - A helper routine for putting decimal numbers * without rich format of printf(). * only 'unsigned long long' is supported. * @m: seq_file identifying the buffer to which data should be written * @delimiter: a string which is printed before the number * @num: the number * @width: a minimum field width * * This routine will put strlen(delimiter) + number into seq_filed. * This routine is very quick when you show lots of numbers. * In usual cases, it will be better to use seq_printf(). It's easier to read.
*/ void seq_put_decimal_ull_width(struct seq_file *m, constchar *delimiter, unsignedlonglong num, unsignedint width)
{ int len;
if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */ goto overflow;
if (delimiter && delimiter[0]) { if (delimiter[1] == 0)
seq_putc(m, delimiter[0]); else
seq_puts(m, delimiter);
}
if (!width)
width = 1;
if (m->count + width >= m->size) goto overflow;
len = num_to_str(m->buf + m->count, m->size - m->count, num, width); if (!len) goto overflow;
/** * seq_put_hex_ll - put a number in hexadecimal notation * @m: seq_file identifying the buffer to which data should be written * @delimiter: a string which is printed before the number * @v: the number * @width: a minimum field width * * seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "%08llx", v) * * This routine is very quick when you show lots of numbers. * In usual cases, it will be better to use seq_printf(). It's easier to read.
*/ void seq_put_hex_ll(struct seq_file *m, constchar *delimiter, unsignedlonglong v, unsignedint width)
{ unsignedint len; int i;
if (delimiter && delimiter[0]) { if (delimiter[1] == 0)
seq_putc(m, delimiter[0]); else
seq_puts(m, delimiter);
}
/* If x is 0, the result of __builtin_clzll is undefined */ if (v == 0)
len = 1; else
len = (sizeof(v) * 8 - __builtin_clzll(v) + 3) / 4;
if (len < width)
len = width;
if (m->count + len > m->size) {
seq_set_overflow(m); return;
}
for (i = len - 1; i >= 0; i--) {
m->buf[m->count + i] = hex_asc[0xf & v];
v = v >> 4;
}
m->count += len;
}
/** * seq_write - write arbitrary data to buffer * @seq: seq_file identifying the buffer to which data should be written * @data: data address * @len: number of bytes * * Return 0 on success, non-zero otherwise.
*/ int seq_write(struct seq_file *seq, constvoid *data, size_t len)
{ if (seq->count + len < seq->size) {
memcpy(seq->buf + seq->count, data, len);
seq->count += len; return 0;
}
seq_set_overflow(seq); return -1;
}
EXPORT_SYMBOL(seq_write);
/** * seq_pad - write padding spaces to buffer * @m: seq_file identifying the buffer to which data should be written * @c: the byte to append after padding if non-zero
*/ void seq_pad(struct seq_file *m, char c)
{ int size = m->pad_until - m->count; if (size > 0) { if (size + m->count > m->size) {
seq_set_overflow(m); return;
}
memset(m->buf + m->count, ' ', size);
m->count += size;
} if (c)
seq_putc(m, c);
}
EXPORT_SYMBOL(seq_pad);
/* A complete analogue of print_hex_dump() */ void seq_hex_dump(struct seq_file *m, constchar *prefix_str, int prefix_type, int rowsize, int groupsize, constvoid *buf, size_t len, bool ascii)
{ const u8 *ptr = buf; int i, linelen, remaining = len; char *buffer;
size_t size; int ret;
if (rowsize != 16 && rowsize != 32)
rowsize = 16;
for (i = 0; i < len && !seq_has_overflowed(m); i += rowsize) {
linelen = min(remaining, rowsize);
remaining -= rowsize;
/** * seq_hlist_start - start an iteration of a hlist * @head: the head of the hlist * @pos: the start position of the sequence * * Called at seq_file->op->start().
*/ struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
{ struct hlist_node *node;
/** * seq_hlist_start_head - start an iteration of a hlist * @head: the head of the hlist * @pos: the start position of the sequence * * Called at seq_file->op->start(). Call this function if you want to * print a header at the top of the output.
*/ struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
{ if (!pos) return SEQ_START_TOKEN;
/** * seq_hlist_next - move to the next position of the hlist * @v: the current iterator * @head: the head of the hlist * @ppos: the current position * * Called at seq_file->op->next().
*/ struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
loff_t *ppos)
{ struct hlist_node *node = v;
++*ppos; if (v == SEQ_START_TOKEN) return head->first; else return node->next;
}
EXPORT_SYMBOL(seq_hlist_next);
/** * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU * @head: the head of the hlist * @pos: the start position of the sequence * * Called at seq_file->op->start(). * * This list-traversal primitive may safely run concurrently with * the _rcu list-mutation primitives such as hlist_add_head_rcu() * as long as the traversal is guarded by rcu_read_lock().
*/ struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
loff_t pos)
{ struct hlist_node *node;
/** * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU * @head: the head of the hlist * @pos: the start position of the sequence * * Called at seq_file->op->start(). Call this function if you want to * print a header at the top of the output. * * This list-traversal primitive may safely run concurrently with * the _rcu list-mutation primitives such as hlist_add_head_rcu() * as long as the traversal is guarded by rcu_read_lock().
*/ struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
loff_t pos)
{ if (!pos) return SEQ_START_TOKEN;
/** * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU * @v: the current iterator * @head: the head of the hlist * @ppos: the current position * * Called at seq_file->op->next(). * * This list-traversal primitive may safely run concurrently with * the _rcu list-mutation primitives such as hlist_add_head_rcu() * as long as the traversal is guarded by rcu_read_lock().
*/ struct hlist_node *seq_hlist_next_rcu(void *v, struct hlist_head *head,
loff_t *ppos)
{ struct hlist_node *node = v;
++*ppos; if (v == SEQ_START_TOKEN) return rcu_dereference(head->first); else return rcu_dereference(node->next);
}
EXPORT_SYMBOL(seq_hlist_next_rcu);
/** * seq_hlist_start_percpu - start an iteration of a percpu hlist array * @head: pointer to percpu array of struct hlist_heads * @cpu: pointer to cpu "cursor" * @pos: start position of sequence * * Called at seq_file->op->start().
*/ struct hlist_node *
seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
{ struct hlist_node *node;
/** * seq_hlist_next_percpu - move to the next position of the percpu hlist array * @v: pointer to current hlist_node * @head: pointer to percpu array of struct hlist_heads * @cpu: pointer to cpu "cursor" * @pos: start position of sequence * * Called at seq_file->op->next().
*/ struct hlist_node *
seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head, int *cpu, loff_t *pos)
{ struct hlist_node *node = v;
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