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Commit 33da8892 authored by Eric Biederman's avatar Eric Biederman Committed by Linus Torvalds
Browse files

seq_file: move traverse so it can be used from seq_read 



In 2.6.25 some /proc files were converted to use the seq_file
infrastructure.  But seq_files do not correctly support pread(), which
broke some usersapce applications.

To handle pread correctly we can't assume that f_pos is where we left it
in seq_read.  So move traverse() so that we can eventually use it in
seq_read and do thus some day support pread().

Signed-off-by: default avatarEric Biederman <ebiederm@xmission.com>
Cc: Paul Turner <pjt@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 361916a9

fs/seq_file.c

+57 −57
Original line number Diff line number Diff line
@@ -54,6 +54,63 @@ int seq_open(struct file *file, const struct seq_operations *op) 
}

EXPORT_SYMBOL(seq_open);



static int traverse(struct seq_file *m, loff_t offset)

{

	loff_t pos = 0, index;

	int error = 0;

	void *p;



	m->version = 0;

	index = 0;

	m->count = m->from = 0;

	if (!offset) {

		m->index = index;

		return 0;

	}

	if (!m->buf) {

		m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);

		if (!m->buf)

			return -ENOMEM;

	}

	p = m->op->start(m, &index);

	while (p) {

		error = PTR_ERR(p);

		if (IS_ERR(p))

			break;

		error = m->op->show(m, p);

		if (error < 0)

			break;

		if (unlikely(error)) {

			error = 0;

			m->count = 0;

		}

		if (m->count == m->size)

			goto Eoverflow;

		if (pos + m->count > offset) {

			m->from = offset - pos;

			m->count -= m->from;

			m->index = index;

			break;

		}

		pos += m->count;

		m->count = 0;

		if (pos == offset) {

			index++;

			m->index = index;

			break;

		}

		p = m->op->next(m, p, &index);

	}

	m->op->stop(m, p);

	return error;



Eoverflow:

	m->op->stop(m, p);

	kfree(m->buf);

	m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);

	return !m->buf ? -ENOMEM : -EAGAIN;

}



/**

 *	seq_read -	->read() method for sequential files.

 *	@file: the file to read from
@@ -186,63 +243,6 @@ Efault: 
}

EXPORT_SYMBOL(seq_read);



static int traverse(struct seq_file *m, loff_t offset)

{

	loff_t pos = 0, index;

	int error = 0;

	void *p;



	m->version = 0;

	index = 0;

	m->count = m->from = 0;

	if (!offset) {

		m->index = index;

		return 0;

	}

	if (!m->buf) {

		m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);

		if (!m->buf)

			return -ENOMEM;

	}

	p = m->op->start(m, &index);

	while (p) {

		error = PTR_ERR(p);

		if (IS_ERR(p))

			break;

		error = m->op->show(m, p);

		if (error < 0)

			break;

		if (unlikely(error)) {

			error = 0;

			m->count = 0;

		}

		if (m->count == m->size)

			goto Eoverflow;

		if (pos + m->count > offset) {

			m->from = offset - pos;

			m->count -= m->from;

			m->index = index;

			break;

		}

		pos += m->count;

		m->count = 0;

		if (pos == offset) {

			index++;

			m->index = index;

			break;

		}

		p = m->op->next(m, p, &index);

	}

	m->op->stop(m, p);

	return error;



Eoverflow:

	m->op->stop(m, p);

	kfree(m->buf);

	m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);

	return !m->buf ? -ENOMEM : -EAGAIN;

}



/**

 *	seq_lseek -	->llseek() method for sequential files.

 *	@file: the file in question