[net-next-2.6.git] / fs / seq_file.c

/*
 * linux/fs/seq_file.c
 *
 * helper functions for making synthetic files from sequences of records.
 * initial implementation -- AV, Oct 2001.
 */

#include <linux/fs.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/slab.h>

#include <asm/uaccess.h>
#include <asm/page.h>

/**
 *	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.
 */
int seq_open(struct file *file, struct seq_operations *op)
{
	struct seq_file *p = kmalloc(sizeof(*p), GFP_KERNEL);
	if (!p)
		return -ENOMEM;
	memset(p, 0, sizeof(*p));
	sema_init(&p->sem, 1);
	p->op = op;
	file->private_data = p;

	/*
	 * Wrappers around seq_open(e.g. swaps_open) need to be
	 * aware of this. If they set f_version themselves, they
	 * should call seq_open first and then set f_version.
	 */
	file->f_version = 0;

	/* SEQ files support lseek, but not pread/pwrite */
	file->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
	return 0;
}
EXPORT_SYMBOL(seq_open);

/**
 *	seq_read -	->read() method for sequential files.
 *	@file, @buf, @size, @ppos: see file_operations method
 *
 *	Ready-made ->f_op->read()
 */
ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
	struct seq_file *m = (struct seq_file *)file->private_data;
	size_t copied = 0;
	loff_t pos;
	size_t n;
	void *p;
	int err = 0;

	down(&m->sem);
	/*
	 * seq_file->op->..m_start/m_stop/m_next may do special actions
	 * or optimisations based on the file->f_version, so we want to
	 * pass the file->f_version to those methods.
	 *
	 * seq_file->version is just copy of f_version, and seq_file
	 * methods can treat it simply as file version.
	 * It is copied in first and copied out after all operations.
	 * It is convenient to have it as  part of structure to avoid the
	 * need of passing another argument to all the seq_file methods.
	 */
	m->version = file->f_version;
	/* grab buffer if we didn't have one */
	if (!m->buf) {
		m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
		if (!m->buf)
			goto Enomem;
	}
	/* if not empty - flush it first */
	if (m->count) {
		n = min(m->count, size);
		err = copy_to_user(buf, m->buf + m->from, n);
		if (err)
			goto Efault;
		m->count -= n;
		m->from += n;
		size -= n;
		buf += n;
		copied += n;
		if (!m->count)
			m->index++;
		if (!size)
			goto Done;
	}
	/* we need at least one record in buffer */
	while (1) {
		pos = m->index;
		p = m->op->start(m, &pos);
		err = PTR_ERR(p);
		if (!p || IS_ERR(p))
			break;
		err = m->op->show(m, p);
		if (err)
			break;
		if (m->count < m->size)
			goto Fill;
		m->op->stop(m, p);
		kfree(m->buf);
		m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
		if (!m->buf)
			goto Enomem;
		m->count = 0;
		m->version = 0;
	}
	m->op->stop(m, p);
	m->count = 0;
	goto Done;
Fill:
	/* they want more? let's try to get some more */
	while (m->count < size) {
		size_t offs = m->count;
		loff_t next = pos;
		p = m->op->next(m, p, &next);
		if (!p || IS_ERR(p)) {
			err = PTR_ERR(p);
			break;
		}
		err = m->op->show(m, p);
		if (err || m->count == m->size) {
			m->count = offs;
			break;
		}
		pos = next;
	}
	m->op->stop(m, p);
	n = min(m->count, size);
	err = copy_to_user(buf, m->buf, n);
	if (err)
		goto Efault;
	copied += n;
	m->count -= n;
	if (m->count)
		m->from = n;
	else
		pos++;
	m->index = pos;
Done:
	if (!copied)
		copied = err;
	else
		*ppos += copied;
	file->f_version = m->version;
	up(&m->sem);
	return copied;
Enomem:
	err = -ENOMEM;
	goto Done;
Efault:
	err = -EFAULT;
	goto Done;
}
EXPORT_SYMBOL(seq_read);

static int traverse(struct seq_file *m, loff_t offset)
{
	loff_t pos = 0;
	int error = 0;
	void *p;

	m->version = 0;
	m->index = 0;
	m->count = m->from = 0;
	if (!offset)
		return 0;
	if (!m->buf) {
		m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
		if (!m->buf)
			return -ENOMEM;
	}
	p = m->op->start(m, &m->index);
	while (p) {
		error = PTR_ERR(p);
		if (IS_ERR(p))
			break;
		error = m->op->show(m, p);
		if (error)
			break;
		if (m->count == m->size)
			goto Eoverflow;
		if (pos + m->count > offset) {
			m->from = offset - pos;
			m->count -= m->from;
			break;
		}
		pos += m->count;
		m->count = 0;
		if (pos == offset) {
			m->index++;
			break;
		}
		p = m->op->next(m, p, &m->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, @offset, @origin: see file_operations method
 *
 *	Ready-made ->f_op->llseek()
 */
loff_t seq_lseek(struct file *file, loff_t offset, int origin)
{
	struct seq_file *m = (struct seq_file *)file->private_data;
	long long retval = -EINVAL;

	down(&m->sem);
	m->version = file->f_version;
	switch (origin) {
		case 1:
			offset += file->f_pos;
		case 0:
			if (offset < 0)
				break;
			retval = offset;
			if (offset != file->f_pos) {
				while ((retval=traverse(m, offset)) == -EAGAIN)
					;
				if (retval) {
					/* with extreme prejudice... */
					file->f_pos = 0;
					m->version = 0;
					m->index = 0;
					m->count = 0;
				} else {
					retval = file->f_pos = offset;
				}
			}
	}
	up(&m->sem);
	file->f_version = m->version;
	return retval;
}
EXPORT_SYMBOL(seq_lseek);

/**
 *	seq_release -	free the structures associated with sequential file.
 *	@file: file in question
 *	@inode: file->f_dentry->d_inode
 *
 *	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 = (struct seq_file *)file->private_data;
	kfree(m->buf);
	kfree(m);
	return 0;
}
EXPORT_SYMBOL(seq_release);

/**
 *	seq_escape -	print string into buffer, escaping some characters
 *	@m:	target buffer
 *	@s:	string
 *	@esc:	set of characters that need escaping
 *
 *	Puts string into buffer, replacing each occurrence of character from
 *	@esc with usual octal escape.  Returns 0 in case of success, -1 - in
 *	case of overflow.
 */
int seq_escape(struct seq_file *m, const char *s, const char *esc)
{
	char *end = m->buf + m->size;
        char *p;
	char c;

        for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) {
		if (!strchr(esc, c)) {
			*p++ = c;
			continue;
		}
		if (p + 3 < end) {
			*p++ = '\\';
			*p++ = '0' + ((c & 0300) >> 6);
			*p++ = '0' + ((c & 070) >> 3);
			*p++ = '0' + (c & 07);
			continue;
		}
		m->count = m->size;
		return -1;
        }
	m->count = p - m->buf;
        return 0;
}
EXPORT_SYMBOL(seq_escape);

int seq_printf(struct seq_file *m, const char *f, ...)
{
	va_list args;
	int len;

	if (m->count < m->size) {
		va_start(args, f);
		len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
		va_end(args);
		if (m->count + len < m->size) {
			m->count += len;
			return 0;
		}
	}
	m->count = m->size;
	return -1;
}
EXPORT_SYMBOL(seq_printf);

int seq_path(struct seq_file *m,
	     struct vfsmount *mnt, struct dentry *dentry,
	     char *esc)
{
	if (m->count < m->size) {
		char *s = m->buf + m->count;
		char *p = d_path(dentry, mnt, s, m->size - m->count);
		if (!IS_ERR(p)) {
			while (s <= p) {
				char c = *p++;
				if (!c) {
					p = m->buf + m->count;
					m->count = s - m->buf;
					return s - p;
				} else if (!strchr(esc, c)) {
					*s++ = c;
				} else if (s + 4 > p) {
					break;
				} else {
					*s++ = '\\';
					*s++ = '0' + ((c & 0300) >> 6);
					*s++ = '0' + ((c & 070) >> 3);
					*s++ = '0' + (c & 07);
				}
			}
		}
	}
	m->count = m->size;
	return -1;
}
EXPORT_SYMBOL(seq_path);

static void *single_start(struct seq_file *p, loff_t *pos)
{
	return NULL + (*pos == 0);
}

static void *single_next(struct seq_file *p, void *v, loff_t *pos)
{
	++*pos;
	return NULL;
}

static void single_stop(struct seq_file *p, void *v)
{
}

int single_open(struct file *file, int (*show)(struct seq_file *, void *),
		void *data)
{
	struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL);
	int res = -ENOMEM;

	if (op) {
		op->start = single_start;
		op->next = single_next;
		op->stop = single_stop;
		op->show = show;
		res = seq_open(file, op);
		if (!res)
			((struct seq_file *)file->private_data)->private = data;
		else
			kfree(op);
	}
	return res;
}
EXPORT_SYMBOL(single_open);

int single_release(struct inode *inode, struct file *file)
{
	struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
	int res = seq_release(inode, file);
	kfree(op);
	return res;
}
EXPORT_SYMBOL(single_release);

int seq_release_private(struct inode *inode, struct file *file)
{
	struct seq_file *seq = file->private_data;

	kfree(seq->private);
	seq->private = NULL;
	return seq_release(inode, file);
}
EXPORT_SYMBOL(seq_release_private);

int seq_putc(struct seq_file *m, char c)
{
	if (m->count < m->size) {
		m->buf[m->count++] = c;
		return 0;
	}
	return -1;
}
EXPORT_SYMBOL(seq_putc);

int seq_puts(struct seq_file *m, const char *s)
{
	int len = strlen(s);
	if (m->count + len < m->size) {
		memcpy(m->buf + m->count, s, len);
		m->count += len;
		return 0;
	}
	m->count = m->size;
	return -1;
}
EXPORT_SYMBOL(seq_puts);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/seq_file.c
	3	*
	4	* helper functions for making synthetic files from sequences of records.
	5	* initial implementation -- AV, Oct 2001.
	6	*/
	7
	8	#include <linux/fs.h>
	9	#include <linux/module.h>
	10	#include <linux/seq_file.h>
	11	#include <linux/slab.h>
	12
	13	#include <asm/uaccess.h>
	14	#include <asm/page.h>
	15
	16	/**
	17	* seq_open - initialize sequential file
	18	* @file: file we initialize
	19	* @op: method table describing the sequence
	20	*
	21	* seq_open() sets @file, associating it with a sequence described
	22	* by @op. @op->start() sets the iterator up and returns the first
	23	* element of sequence. @op->stop() shuts it down. @op->next()
	24	* returns the next element of sequence. @op->show() prints element
	25	* into the buffer. In case of error ->start() and ->next() return
	26	* ERR_PTR(error). In the end of sequence they return %NULL. ->show()
	27	* returns 0 in case of success and negative number in case of error.
	28	*/
	29	int seq_open(struct file file, struct seq_operations op)
	30	{
	31	struct seq_file p = kmalloc(sizeof(p), GFP_KERNEL);
	32	if (!p)
	33	return -ENOMEM;
	34	memset(p, 0, sizeof(*p));
	35	sema_init(&p->sem, 1);
	36	p->op = op;
	37	file->private_data = p;
	38
	39	/*
	40	* Wrappers around seq_open(e.g. swaps_open) need to be
	41	* aware of this. If they set f_version themselves, they
	42	* should call seq_open first and then set f_version.
	43	*/
	44	file->f_version = 0;
	45
	46	/* SEQ files support lseek, but not pread/pwrite */
	47	file->f_mode &= ~(FMODE_PREAD \| FMODE_PWRITE);
	48	return 0;
	49	}
	50	EXPORT_SYMBOL(seq_open);
	51
	52	/**
	53	* seq_read - ->read() method for sequential files.
	54	* @file, @buf, @size, @ppos: see file_operations method
	55	*
	56	* Ready-made ->f_op->read()
	57	*/
	58	ssize_t seq_read(struct file file, char __user buf, size_t size, loff_t *ppos)
	59	{
	60	struct seq_file m = (struct seq_file )file->private_data;
	61	size_t copied = 0;
	62	loff_t pos;
	63	size_t n;
	64	void *p;
65	int err = 0;
66
67	down(&m->sem);
68	/*
69	* seq_file->op->..m_start/m_stop/m_next may do special actions
70	* or optimisations based on the file->f_version, so we want to
71	* pass the file->f_version to those methods.
72	*
73	* seq_file->version is just copy of f_version, and seq_file
74	* methods can treat it simply as file version.
75	* It is copied in first and copied out after all operations.
76	* It is convenient to have it as part of structure to avoid the
77	* need of passing another argument to all the seq_file methods.
78	*/
79	m->version = file->f_version;
80	/* grab buffer if we didn't have one */
81	if (!m->buf) {
82	m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
83	if (!m->buf)
84	goto Enomem;
85	}
86	/* if not empty - flush it first */
87	if (m->count) {
88	n = min(m->count, size);
89	err = copy_to_user(buf, m->buf + m->from, n);
90	if (err)
91	goto Efault;
92	m->count -= n;
93	m->from += n;
94	size -= n;
95	buf += n;
96	copied += n;
97	if (!m->count)
98	m->index++;
99	if (!size)
100	goto Done;
101	}
102	/* we need at least one record in buffer */
103	while (1) {
104	pos = m->index;
105	p = m->op->start(m, &pos);
106	err = PTR_ERR(p);
107	if (!p \|\| IS_ERR(p))
108	break;
109	err = m->op->show(m, p);
110	if (err)
111	break;
112	if (m->count < m->size)
113	goto Fill;
114	m->op->stop(m, p);
115	kfree(m->buf);
116	m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
117	if (!m->buf)
118	goto Enomem;
119	m->count = 0;
120	m->version = 0;
121	}
122	m->op->stop(m, p);
123	m->count = 0;
124	goto Done;
125	Fill:
126	/* they want more? let's try to get some more */
127	while (m->count < size) {
128	size_t offs = m->count;
129	loff_t next = pos;
130	p = m->op->next(m, p, &next);
131	if (!p \|\| IS_ERR(p)) {
132	err = PTR_ERR(p);
133	break;
134	}
135	err = m->op->show(m, p);
136	if (err \|\| m->count == m->size) {
137	m->count = offs;
138	break;
139	}
140	pos = next;
141	}
142	m->op->stop(m, p);
143	n = min(m->count, size);
144	err = copy_to_user(buf, m->buf, n);
145	if (err)
146	goto Efault;
147	copied += n;
148	m->count -= n;
149	if (m->count)
150	m->from = n;
151	else
152	pos++;
153	m->index = pos;
154	Done:
155	if (!copied)
156	copied = err;
157	else
158	*ppos += copied;
159	file->f_version = m->version;
160	up(&m->sem);
161	return copied;
162	Enomem:
163	err = -ENOMEM;
164	goto Done;
165	Efault:
166	err = -EFAULT;
167	goto Done;
168	}
169	EXPORT_SYMBOL(seq_read);
170
171	static int traverse(struct seq_file *m, loff_t offset)
172	{
173	loff_t pos = 0;
174	int error = 0;
175	void *p;
176
177	m->version = 0;
178	m->index = 0;
179	m->count = m->from = 0;
180	if (!offset)
181	return 0;
182	if (!m->buf) {
183	m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
184	if (!m->buf)
185	return -ENOMEM;
186	}
187	p = m->op->start(m, &m->index);
188	while (p) {
189	error = PTR_ERR(p);
190	if (IS_ERR(p))
191	break;
192	error = m->op->show(m, p);
193	if (error)
194	break;
195	if (m->count == m->size)
196	goto Eoverflow;
197	if (pos + m->count > offset) {
198	m->from = offset - pos;
199	m->count -= m->from;
200	break;
201	}
202	pos += m->count;
203	m->count = 0;
204	if (pos == offset) {
205	m->index++;
206	break;
207	}
208	p = m->op->next(m, p, &m->index);
209	}
210	m->op->stop(m, p);
211	return error;
212
213	Eoverflow:
214	m->op->stop(m, p);
215	kfree(m->buf);
216	m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
217	return !m->buf ? -ENOMEM : -EAGAIN;
218	}
219
220	/**
221	* seq_lseek - ->llseek() method for sequential files.
222	* @file, @offset, @origin: see file_operations method
223	*
224	* Ready-made ->f_op->llseek()
225	*/
226	loff_t seq_lseek(struct file *file, loff_t offset, int origin)
227	{
228	struct seq_file m = (struct seq_file )file->private_data;
229	long long retval = -EINVAL;
230
231	down(&m->sem);
232	m->version = file->f_version;
233	switch (origin) {
234	case 1:
235	offset += file->f_pos;
236	case 0:
237	if (offset < 0)
238	break;
239	retval = offset;
240	if (offset != file->f_pos) {
241	while ((retval=traverse(m, offset)) == -EAGAIN)
242	;
243	if (retval) {
244	/* with extreme prejudice... */
245	file->f_pos = 0;
246	m->version = 0;
247	m->index = 0;
248	m->count = 0;
249	} else {
250	retval = file->f_pos = offset;
251	}
252	}
253	}
254	up(&m->sem);
255	file->f_version = m->version;
256	return retval;
257	}
258	EXPORT_SYMBOL(seq_lseek);
259
260	/**
261	* seq_release - free the structures associated with sequential file.
262	* @file: file in question
263	* @inode: file->f_dentry->d_inode
264	*
265	* Frees the structures associated with sequential file; can be used
266	* as ->f_op->release() if you don't have private data to destroy.
267	*/
268	int seq_release(struct inode inode, struct file file)
269	{
270	struct seq_file m = (struct seq_file )file->private_data;
271	kfree(m->buf);
272	kfree(m);
273	return 0;
274	}
275	EXPORT_SYMBOL(seq_release);
276
277	/**
278	* seq_escape - print string into buffer, escaping some characters
279	* @m: target buffer
280	* @s: string
281	* @esc: set of characters that need escaping
282	*
283	* Puts string into buffer, replacing each occurrence of character from
284	* @esc with usual octal escape. Returns 0 in case of success, -1 - in
285	* case of overflow.
286	*/
287	int seq_escape(struct seq_file m, const char s, const char *esc)
288	{
289	char *end = m->buf + m->size;
290	char *p;
291	char c;
292
293	for (p = m->buf + m->count; (c = *s) != '\0' && p < end; s++) {
294	if (!strchr(esc, c)) {
295	*p++ = c;
296	continue;
297	}
298	if (p + 3 < end) {
299	*p++ = '\\';
300	*p++ = '0' + ((c & 0300) >> 6);
301	*p++ = '0' + ((c & 070) >> 3);
302	*p++ = '0' + (c & 07);
303	continue;
304	}
305	m->count = m->size;
306	return -1;
307	}
308	m->count = p - m->buf;
309	return 0;
310	}
311	EXPORT_SYMBOL(seq_escape);
312
313	int seq_printf(struct seq_file m, const char f, ...)
314	{
315	va_list args;
316	int len;
317
318	if (m->count < m->size) {
319	va_start(args, f);
320	len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
321	va_end(args);
322	if (m->count + len < m->size) {
323	m->count += len;
324	return 0;
325	}
326	}
327	m->count = m->size;
328	return -1;
329	}
330	EXPORT_SYMBOL(seq_printf);
331
332	int seq_path(struct seq_file *m,
333	struct vfsmount mnt, struct dentry dentry,
334	char *esc)
335	{
336	if (m->count < m->size) {
337	char *s = m->buf + m->count;
338	char *p = d_path(dentry, mnt, s, m->size - m->count);
339	if (!IS_ERR(p)) {
340	while (s <= p) {
341	char c = *p++;
342	if (!c) {
343	p = m->buf + m->count;
344	m->count = s - m->buf;
345	return s - p;
346	} else if (!strchr(esc, c)) {
347	*s++ = c;
348	} else if (s + 4 > p) {
349	break;
350	} else {
351	*s++ = '\\';
352	*s++ = '0' + ((c & 0300) >> 6);
353	*s++ = '0' + ((c & 070) >> 3);
354	*s++ = '0' + (c & 07);
355	}
356	}
357	}
358	}
359	m->count = m->size;
360	return -1;
361	}
362	EXPORT_SYMBOL(seq_path);
363
364	static void single_start(struct seq_file p, loff_t *pos)
365	{
366	return NULL + (*pos == 0);
367	}
368
369	static void single_next(struct seq_file p, void v, loff_t pos)
370	{
371	++*pos;
372	return NULL;
373	}
374
375	static void single_stop(struct seq_file p, void v)
376	{
377	}
378
379	int single_open(struct file file, int (show)(struct seq_file , void ),
380	void *data)
381	{
382	struct seq_operations op = kmalloc(sizeof(op), GFP_KERNEL);
383	int res = -ENOMEM;
384
385	if (op) {
386	op->start = single_start;
387	op->next = single_next;
388	op->stop = single_stop;
389	op->show = show;
390	res = seq_open(file, op);
391	if (!res)
392	((struct seq_file *)file->private_data)->private = data;
393	else
394	kfree(op);
395	}
396	return res;
397	}
398	EXPORT_SYMBOL(single_open);
399
400	int single_release(struct inode inode, struct file file)
401	{
402	struct seq_operations op = ((struct seq_file )file->private_data)->op;
403	int res = seq_release(inode, file);
404	kfree(op);
405	return res;
406	}
407	EXPORT_SYMBOL(single_release);
408
409	int seq_release_private(struct inode inode, struct file file)
410	{
411	struct seq_file *seq = file->private_data;
412
413	kfree(seq->private);
414	seq->private = NULL;
415	return seq_release(inode, file);
416	}
417	EXPORT_SYMBOL(seq_release_private);
418
419	int seq_putc(struct seq_file *m, char c)
420	{
421	if (m->count < m->size) {
422	m->buf[m->count++] = c;
423	return 0;
424	}
425	return -1;
426	}
427	EXPORT_SYMBOL(seq_putc);
428
429	int seq_puts(struct seq_file m, const char s)
430	{
431	int len = strlen(s);
432	if (m->count + len < m->size) {
433	memcpy(m->buf + m->count, s, len);
434	m->count += len;
435	return 0;
436	}
437	m->count = m->size;
438	return -1;
439	}
440	EXPORT_SYMBOL(seq_puts);