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![Al Viro](/assets/img/avatar_default.png)
Allow caller of seq_open() to kmalloc() seq_file + whatever else they want and set ->private_data to it. seq_open() will then abstain from doing allocation itself. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
449 lines
9.6 KiB
C
449 lines
9.6 KiB
C
/*
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* linux/fs/seq_file.c
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*
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* helper functions for making synthetic files from sequences of records.
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* initial implementation -- AV, Oct 2001.
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*/
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#include <linux/fs.h>
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#include <linux/module.h>
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#include <linux/seq_file.h>
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#include <linux/slab.h>
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#include <asm/uaccess.h>
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#include <asm/page.h>
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/**
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* seq_open - initialize sequential file
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* @file: file we initialize
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* @op: method table describing the sequence
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*
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* seq_open() sets @file, associating it with a sequence described
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* by @op. @op->start() sets the iterator up and returns the first
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* element of sequence. @op->stop() shuts it down. @op->next()
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* returns the next element of sequence. @op->show() prints element
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* into the buffer. In case of error ->start() and ->next() return
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* ERR_PTR(error). In the end of sequence they return %NULL. ->show()
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* returns 0 in case of success and negative number in case of error.
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*/
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int seq_open(struct file *file, struct seq_operations *op)
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{
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struct seq_file *p = file->private_data;
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if (!p) {
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p = kmalloc(sizeof(*p), GFP_KERNEL);
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if (!p)
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return -ENOMEM;
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file->private_data = p;
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}
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memset(p, 0, sizeof(*p));
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sema_init(&p->sem, 1);
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p->op = op;
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/*
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* Wrappers around seq_open(e.g. swaps_open) need to be
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* aware of this. If they set f_version themselves, they
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* should call seq_open first and then set f_version.
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*/
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file->f_version = 0;
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/* SEQ files support lseek, but not pread/pwrite */
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file->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
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return 0;
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}
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EXPORT_SYMBOL(seq_open);
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/**
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* seq_read - ->read() method for sequential files.
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* @file: the file to read from
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* @buf: the buffer to read to
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* @size: the maximum number of bytes to read
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* @ppos: the current position in the file
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*
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* Ready-made ->f_op->read()
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*/
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ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
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{
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struct seq_file *m = (struct seq_file *)file->private_data;
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size_t copied = 0;
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loff_t pos;
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size_t n;
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void *p;
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int err = 0;
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down(&m->sem);
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/*
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* seq_file->op->..m_start/m_stop/m_next may do special actions
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* or optimisations based on the file->f_version, so we want to
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* pass the file->f_version to those methods.
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*
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* seq_file->version is just copy of f_version, and seq_file
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* methods can treat it simply as file version.
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* It is copied in first and copied out after all operations.
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* It is convenient to have it as part of structure to avoid the
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* need of passing another argument to all the seq_file methods.
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*/
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m->version = file->f_version;
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/* grab buffer if we didn't have one */
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if (!m->buf) {
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m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
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if (!m->buf)
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goto Enomem;
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}
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/* if not empty - flush it first */
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if (m->count) {
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n = min(m->count, size);
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err = copy_to_user(buf, m->buf + m->from, n);
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if (err)
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goto Efault;
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m->count -= n;
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m->from += n;
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size -= n;
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buf += n;
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copied += n;
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if (!m->count)
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m->index++;
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if (!size)
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goto Done;
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}
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/* we need at least one record in buffer */
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while (1) {
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pos = m->index;
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p = m->op->start(m, &pos);
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err = PTR_ERR(p);
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if (!p || IS_ERR(p))
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break;
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err = m->op->show(m, p);
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if (err)
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break;
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if (m->count < m->size)
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goto Fill;
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m->op->stop(m, p);
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kfree(m->buf);
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m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
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if (!m->buf)
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goto Enomem;
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m->count = 0;
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m->version = 0;
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}
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m->op->stop(m, p);
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m->count = 0;
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goto Done;
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Fill:
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/* they want more? let's try to get some more */
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while (m->count < size) {
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size_t offs = m->count;
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loff_t next = pos;
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p = m->op->next(m, p, &next);
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if (!p || IS_ERR(p)) {
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err = PTR_ERR(p);
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break;
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}
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err = m->op->show(m, p);
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if (err || m->count == m->size) {
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m->count = offs;
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break;
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}
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pos = next;
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}
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m->op->stop(m, p);
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n = min(m->count, size);
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err = copy_to_user(buf, m->buf, n);
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if (err)
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goto Efault;
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copied += n;
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m->count -= n;
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if (m->count)
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m->from = n;
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else
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pos++;
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m->index = pos;
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Done:
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if (!copied)
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copied = err;
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else
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*ppos += copied;
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file->f_version = m->version;
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up(&m->sem);
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return copied;
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Enomem:
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err = -ENOMEM;
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goto Done;
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Efault:
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err = -EFAULT;
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goto Done;
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}
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EXPORT_SYMBOL(seq_read);
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static int traverse(struct seq_file *m, loff_t offset)
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{
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loff_t pos = 0;
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int error = 0;
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void *p;
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m->version = 0;
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m->index = 0;
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m->count = m->from = 0;
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if (!offset)
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return 0;
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if (!m->buf) {
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m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
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if (!m->buf)
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return -ENOMEM;
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}
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p = m->op->start(m, &m->index);
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while (p) {
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error = PTR_ERR(p);
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if (IS_ERR(p))
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break;
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error = m->op->show(m, p);
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if (error)
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break;
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if (m->count == m->size)
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goto Eoverflow;
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if (pos + m->count > offset) {
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m->from = offset - pos;
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m->count -= m->from;
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break;
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}
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pos += m->count;
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m->count = 0;
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if (pos == offset) {
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m->index++;
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break;
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}
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p = m->op->next(m, p, &m->index);
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}
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m->op->stop(m, p);
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return error;
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Eoverflow:
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m->op->stop(m, p);
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kfree(m->buf);
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m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
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return !m->buf ? -ENOMEM : -EAGAIN;
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}
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/**
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* seq_lseek - ->llseek() method for sequential files.
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* @file: the file in question
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* @offset: new position
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* @origin: 0 for absolute, 1 for relative position
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*
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* Ready-made ->f_op->llseek()
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*/
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loff_t seq_lseek(struct file *file, loff_t offset, int origin)
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{
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struct seq_file *m = (struct seq_file *)file->private_data;
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long long retval = -EINVAL;
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down(&m->sem);
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m->version = file->f_version;
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switch (origin) {
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case 1:
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offset += file->f_pos;
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case 0:
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if (offset < 0)
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break;
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retval = offset;
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if (offset != file->f_pos) {
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while ((retval=traverse(m, offset)) == -EAGAIN)
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;
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if (retval) {
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/* with extreme prejudice... */
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file->f_pos = 0;
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m->version = 0;
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m->index = 0;
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m->count = 0;
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} else {
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retval = file->f_pos = offset;
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}
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}
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}
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up(&m->sem);
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file->f_version = m->version;
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return retval;
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}
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EXPORT_SYMBOL(seq_lseek);
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/**
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* seq_release - free the structures associated with sequential file.
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* @file: file in question
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* @inode: file->f_dentry->d_inode
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*
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* Frees the structures associated with sequential file; can be used
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* as ->f_op->release() if you don't have private data to destroy.
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*/
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int seq_release(struct inode *inode, struct file *file)
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{
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struct seq_file *m = (struct seq_file *)file->private_data;
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kfree(m->buf);
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kfree(m);
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return 0;
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}
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EXPORT_SYMBOL(seq_release);
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/**
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* seq_escape - print string into buffer, escaping some characters
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* @m: target buffer
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* @s: string
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* @esc: set of characters that need escaping
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*
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* Puts string into buffer, replacing each occurrence of character from
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* @esc with usual octal escape. Returns 0 in case of success, -1 - in
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* case of overflow.
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*/
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int seq_escape(struct seq_file *m, const char *s, const char *esc)
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{
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char *end = m->buf + m->size;
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char *p;
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char c;
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for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) {
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if (!strchr(esc, c)) {
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*p++ = c;
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continue;
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}
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if (p + 3 < end) {
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*p++ = '\\';
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*p++ = '0' + ((c & 0300) >> 6);
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*p++ = '0' + ((c & 070) >> 3);
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*p++ = '0' + (c & 07);
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continue;
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}
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m->count = m->size;
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return -1;
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}
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m->count = p - m->buf;
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return 0;
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}
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EXPORT_SYMBOL(seq_escape);
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int seq_printf(struct seq_file *m, const char *f, ...)
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{
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va_list args;
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int len;
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if (m->count < m->size) {
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va_start(args, f);
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len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
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va_end(args);
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if (m->count + len < m->size) {
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m->count += len;
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return 0;
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}
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}
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m->count = m->size;
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return -1;
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}
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EXPORT_SYMBOL(seq_printf);
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int seq_path(struct seq_file *m,
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struct vfsmount *mnt, struct dentry *dentry,
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char *esc)
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{
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if (m->count < m->size) {
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char *s = m->buf + m->count;
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char *p = d_path(dentry, mnt, s, m->size - m->count);
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if (!IS_ERR(p)) {
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while (s <= p) {
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char c = *p++;
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if (!c) {
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p = m->buf + m->count;
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m->count = s - m->buf;
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return s - p;
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} else if (!strchr(esc, c)) {
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*s++ = c;
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} else if (s + 4 > p) {
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break;
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} else {
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*s++ = '\\';
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*s++ = '0' + ((c & 0300) >> 6);
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*s++ = '0' + ((c & 070) >> 3);
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*s++ = '0' + (c & 07);
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}
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}
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}
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}
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m->count = m->size;
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return -1;
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}
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EXPORT_SYMBOL(seq_path);
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static void *single_start(struct seq_file *p, loff_t *pos)
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{
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return NULL + (*pos == 0);
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}
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static void *single_next(struct seq_file *p, void *v, loff_t *pos)
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{
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++*pos;
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return NULL;
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}
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static void single_stop(struct seq_file *p, void *v)
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{
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}
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int single_open(struct file *file, int (*show)(struct seq_file *, void *),
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void *data)
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{
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struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL);
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int res = -ENOMEM;
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if (op) {
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op->start = single_start;
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op->next = single_next;
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op->stop = single_stop;
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op->show = show;
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res = seq_open(file, op);
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if (!res)
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((struct seq_file *)file->private_data)->private = data;
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else
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kfree(op);
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}
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return res;
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}
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EXPORT_SYMBOL(single_open);
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int single_release(struct inode *inode, struct file *file)
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{
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struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
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int res = seq_release(inode, file);
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kfree(op);
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return res;
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}
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EXPORT_SYMBOL(single_release);
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int seq_release_private(struct inode *inode, struct file *file)
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{
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struct seq_file *seq = file->private_data;
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kfree(seq->private);
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seq->private = NULL;
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return seq_release(inode, file);
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}
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EXPORT_SYMBOL(seq_release_private);
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int seq_putc(struct seq_file *m, char c)
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{
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if (m->count < m->size) {
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m->buf[m->count++] = c;
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return 0;
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}
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return -1;
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}
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EXPORT_SYMBOL(seq_putc);
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int seq_puts(struct seq_file *m, const char *s)
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{
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int len = strlen(s);
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if (m->count + len < m->size) {
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memcpy(m->buf + m->count, s, len);
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m->count += len;
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return 0;
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}
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m->count = m->size;
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return -1;
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}
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EXPORT_SYMBOL(seq_puts);
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