diff options
Diffstat (limited to 'fs/seq_file.c')
| -rw-r--r-- | fs/seq_file.c | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/fs/seq_file.c b/fs/seq_file.c new file mode 100644 index 000000000000..3786b3f37d70 --- /dev/null +++ b/fs/seq_file.c @@ -0,0 +1,236 @@ +/* + * linux/fs/seq_file.c + * + * helper functions for making syntetic files from sequences of records. + * initial implementation -- AV, Oct 2001. + */ + +#include <linux/malloc.h> +#include <linux/fs.h> +#include <linux/seq_file.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) + (*ppos)++; + if (!size) + goto Done; + } + /* we need at least one record in buffer */ + while (1) { + pos = *ppos; + 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++; + *ppos = pos; +Done: + if (!copied) + copied = err; + up(&m->sem); + return copied; +Enomem: + err = -ENOMEM; + goto Done; +Efault: + err = -EFAULT; + goto Done; +} + +/** + * 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; + if (offset != file->f_pos) { + file->f_pos = offset; + m->count = 0; + } + retval = 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; +} |