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/*
* linux/fs/seq_file.c
*
* helper functions for making syntetic files from sequences of records.
* initial implementation -- AV, Oct 2001.
*/
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <asm/uaccess.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;
return 0;
}
/**
* 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 *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;
if (ppos != &file->f_pos)
return -EPIPE;
down(&m->sem);
/* 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->op->stop(m, p);
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;
up(&m->sem);
return copied;
Enomem:
err = -ENOMEM;
goto Done;
Efault:
err = -EFAULT;
goto Done;
}
static int traverse(struct seq_file *m, loff_t offset)
{
loff_t pos = 0;
int error = 0;
void *p;
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);
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 perjudice... */
file->f_pos = 0;
m->index = 0;
m->count = 0;
} else {
retval = file->f_pos = offset;
}
}
}
up(&m->sem);
return retval;
}
/**
* 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;
}
/**
* 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 occurence 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;
}
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;
}
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