/* * 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: the file to read from * @buf: the buffer to read to * @size: the maximum number of bytes to read * @ppos: the current position in the file * * 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: the file in question * @offset: new position * @origin: 0 for absolute, 1 for relative position * * 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);