| /* |
| * 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; |
| } |