diff options
Diffstat (limited to 'fs/seq_file.c')
| -rw-r--r-- | fs/seq_file.c | 968 |
1 files changed, 968 insertions, 0 deletions
diff --git a/fs/seq_file.c b/fs/seq_file.c new file mode 100644 index 000000000..555f82155 --- /dev/null +++ b/fs/seq_file.c @@ -0,0 +1,968 @@ +/* + * 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/export.h> +#include <linux/seq_file.h> +#include <linux/vmalloc.h> +#include <linux/slab.h> +#include <linux/cred.h> +#include <linux/mm.h> + +#include <asm/uaccess.h> +#include <asm/page.h> + +static void seq_set_overflow(struct seq_file *m) +{ + m->count = m->size; +} + +static void *seq_buf_alloc(unsigned long size) +{ + void *buf; + + /* + * __GFP_NORETRY to avoid oom-killings with high-order allocations - + * it's better to fall back to vmalloc() than to kill things. + */ + buf = kmalloc(size, GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN); + if (!buf && size > PAGE_SIZE) + buf = vmalloc(size); + return buf; +} + +/** + * 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. + * Returning SEQ_SKIP means "discard this element and move on". + */ +int seq_open(struct file *file, const struct seq_operations *op) +{ + struct seq_file *p = file->private_data; + + if (!p) { + p = kmalloc(sizeof(*p), GFP_KERNEL); + if (!p) + return -ENOMEM; + file->private_data = p; + } + memset(p, 0, sizeof(*p)); + mutex_init(&p->lock); + p->op = op; +#ifdef CONFIG_USER_NS + p->user_ns = file->f_cred->user_ns; +#endif + + /* + * 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() and pread(). They do not implement + * write() at all, but we clear FMODE_PWRITE here for historical + * reasons. + * + * If a client of seq_files a) implements file.write() and b) wishes to + * support pwrite() then that client will need to implement its own + * file.open() which calls seq_open() and then sets FMODE_PWRITE. + */ + file->f_mode &= ~FMODE_PWRITE; + return 0; +} +EXPORT_SYMBOL(seq_open); + +static int traverse(struct seq_file *m, loff_t offset) +{ + loff_t pos = 0, index; + int error = 0; + void *p; + + m->version = 0; + index = 0; + m->count = m->from = 0; + if (!offset) { + m->index = index; + return 0; + } + if (!m->buf) { + m->buf = seq_buf_alloc(m->size = PAGE_SIZE); + if (!m->buf) + return -ENOMEM; + } + p = m->op->start(m, &index); + while (p) { + error = PTR_ERR(p); + if (IS_ERR(p)) + break; + error = m->op->show(m, p); + if (error < 0) + break; + if (unlikely(error)) { + error = 0; + m->count = 0; + } + if (seq_has_overflowed(m)) + goto Eoverflow; + if (pos + m->count > offset) { + m->from = offset - pos; + m->count -= m->from; + m->index = index; + break; + } + pos += m->count; + m->count = 0; + if (pos == offset) { + index++; + m->index = index; + break; + } + p = m->op->next(m, p, &index); + } + m->op->stop(m, p); + m->index = index; + return error; + +Eoverflow: + m->op->stop(m, p); + kvfree(m->buf); + m->count = 0; + m->buf = seq_buf_alloc(m->size <<= 1); + return !m->buf ? -ENOMEM : -EAGAIN; +} + +/** + * 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 = file->private_data; + size_t copied = 0; + loff_t pos; + size_t n; + void *p; + int err = 0; + + mutex_lock(&m->lock); + + /* + * 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; + + /* Don't assume *ppos is where we left it */ + if (unlikely(*ppos != m->read_pos)) { + while ((err = traverse(m, *ppos)) == -EAGAIN) + ; + if (err) { + /* With prejudice... */ + m->read_pos = 0; + m->version = 0; + m->index = 0; + m->count = 0; + goto Done; + } else { + m->read_pos = *ppos; + } + } + + /* grab buffer if we didn't have one */ + if (!m->buf) { + m->buf = seq_buf_alloc(m->size = PAGE_SIZE); + 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 */ + pos = m->index; + p = m->op->start(m, &pos); + while (1) { + err = PTR_ERR(p); + if (!p || IS_ERR(p)) + break; + err = m->op->show(m, p); + if (err < 0) + break; + if (unlikely(err)) + m->count = 0; + if (unlikely(!m->count)) { + p = m->op->next(m, p, &pos); + m->index = pos; + continue; + } + if (m->count < m->size) + goto Fill; + m->op->stop(m, p); + kvfree(m->buf); + m->count = 0; + m->buf = seq_buf_alloc(m->size <<= 1); + if (!m->buf) + goto Enomem; + m->version = 0; + pos = m->index; + p = m->op->start(m, &pos); + } + 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 (seq_has_overflowed(m) || err) { + m->count = offs; + if (likely(err <= 0)) + 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; + m->read_pos += copied; + } + file->f_version = m->version; + mutex_unlock(&m->lock); + return copied; +Enomem: + err = -ENOMEM; + goto Done; +Efault: + err = -EFAULT; + goto Done; +} +EXPORT_SYMBOL(seq_read); + +/** + * seq_lseek - ->llseek() method for sequential files. + * @file: the file in question + * @offset: new position + * @whence: 0 for absolute, 1 for relative position + * + * Ready-made ->f_op->llseek() + */ +loff_t seq_lseek(struct file *file, loff_t offset, int whence) +{ + struct seq_file *m = file->private_data; + loff_t retval = -EINVAL; + + mutex_lock(&m->lock); + m->version = file->f_version; + switch (whence) { + case SEEK_CUR: + offset += file->f_pos; + case SEEK_SET: + if (offset < 0) + break; + retval = offset; + if (offset != m->read_pos) { + while ((retval = traverse(m, offset)) == -EAGAIN) + ; + if (retval) { + /* with extreme prejudice... */ + file->f_pos = 0; + m->read_pos = 0; + m->version = 0; + m->index = 0; + m->count = 0; + } else { + m->read_pos = offset; + retval = file->f_pos = offset; + } + } else { + file->f_pos = offset; + } + } + file->f_version = m->version; + mutex_unlock(&m->lock); + return retval; +} +EXPORT_SYMBOL(seq_lseek); + +/** + * seq_release - free the structures associated with sequential file. + * @file: file in question + * @inode: its 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 = file->private_data; + kvfree(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; + } + seq_set_overflow(m); + return -1; + } + m->count = p - m->buf; + return 0; +} +EXPORT_SYMBOL(seq_escape); + +int seq_vprintf(struct seq_file *m, const char *f, va_list args) +{ + int len; + + if (m->count < m->size) { + len = vsnprintf(m->buf + m->count, m->size - m->count, f, args); + if (m->count + len < m->size) { + m->count += len; + return 0; + } + } + seq_set_overflow(m); + return -1; +} +EXPORT_SYMBOL(seq_vprintf); + +int seq_printf(struct seq_file *m, const char *f, ...) +{ + int ret; + va_list args; + + va_start(args, f); + ret = seq_vprintf(m, f, args); + va_end(args); + + return ret; +} +EXPORT_SYMBOL(seq_printf); + +/** + * mangle_path - mangle and copy path to buffer beginning + * @s: buffer start + * @p: beginning of path in above buffer + * @esc: set of characters that need escaping + * + * Copy the path from @p to @s, replacing each occurrence of character from + * @esc with usual octal escape. + * Returns pointer past last written character in @s, or NULL in case of + * failure. + */ +char *mangle_path(char *s, const char *p, const char *esc) +{ + while (s <= p) { + char c = *p++; + if (!c) { + return s; + } 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); + } + } + return NULL; +} +EXPORT_SYMBOL(mangle_path); + +/** + * seq_path - seq_file interface to print a pathname + * @m: the seq_file handle + * @path: the struct path to print + * @esc: set of characters to escape in the output + * + * return the absolute path of 'path', as represented by the + * dentry / mnt pair in the path parameter. + */ +int seq_path(struct seq_file *m, const struct path *path, const char *esc) +{ + char *buf; + size_t size = seq_get_buf(m, &buf); + int res = -1; + + if (size) { + char *p = d_path(path, buf, size); + if (!IS_ERR(p)) { + char *end = mangle_path(buf, p, esc); + if (end) + res = end - buf; + } + } + seq_commit(m, res); + + return res; +} +EXPORT_SYMBOL(seq_path); + +/* + * Same as seq_path, but relative to supplied root. + */ +int seq_path_root(struct seq_file *m, const struct path *path, + const struct path *root, const char *esc) +{ + char *buf; + size_t size = seq_get_buf(m, &buf); + int res = -ENAMETOOLONG; + + if (size) { + char *p; + + p = __d_path(path, root, buf, size); + if (!p) + return SEQ_SKIP; + res = PTR_ERR(p); + if (!IS_ERR(p)) { + char *end = mangle_path(buf, p, esc); + if (end) + res = end - buf; + else + res = -ENAMETOOLONG; + } + } + seq_commit(m, res); + + return res < 0 && res != -ENAMETOOLONG ? res : 0; +} + +/* + * returns the path of the 'dentry' from the root of its filesystem. + */ +int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc) +{ + char *buf; + size_t size = seq_get_buf(m, &buf); + int res = -1; + + if (size) { + char *p = dentry_path(dentry, buf, size); + if (!IS_ERR(p)) { + char *end = mangle_path(buf, p, esc); + if (end) + res = end - buf; + } + } + seq_commit(m, res); + + return res; +} + +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_open_size(struct file *file, int (*show)(struct seq_file *, void *), + void *data, size_t size) +{ + char *buf = seq_buf_alloc(size); + int ret; + if (!buf) + return -ENOMEM; + ret = single_open(file, show, data); + if (ret) { + kvfree(buf); + return ret; + } + ((struct seq_file *)file->private_data)->buf = buf; + ((struct seq_file *)file->private_data)->size = size; + return 0; +} +EXPORT_SYMBOL(single_open_size); + +int single_release(struct inode *inode, struct file *file) +{ + const 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); + +void *__seq_open_private(struct file *f, const struct seq_operations *ops, + int psize) +{ + int rc; + void *private; + struct seq_file *seq; + + private = kzalloc(psize, GFP_KERNEL); + if (private == NULL) + goto out; + + rc = seq_open(f, ops); + if (rc < 0) + goto out_free; + + seq = f->private_data; + seq->private = private; + return private; + +out_free: + kfree(private); +out: + return NULL; +} +EXPORT_SYMBOL(__seq_open_private); + +int seq_open_private(struct file *filp, const struct seq_operations *ops, + int psize) +{ + return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM; +} +EXPORT_SYMBOL(seq_open_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; + } + seq_set_overflow(m); + return -1; +} +EXPORT_SYMBOL(seq_puts); + +/* + * A helper routine for putting decimal numbers without rich format of printf(). + * only 'unsigned long long' is supported. + * This routine will put one byte delimiter + number into seq_file. + * This routine is very quick when you show lots of numbers. + * In usual cases, it will be better to use seq_printf(). It's easier to read. + */ +int seq_put_decimal_ull(struct seq_file *m, char delimiter, + unsigned long long num) +{ + int len; + + if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */ + goto overflow; + + if (delimiter) + m->buf[m->count++] = delimiter; + + if (num < 10) { + m->buf[m->count++] = num + '0'; + return 0; + } + + len = num_to_str(m->buf + m->count, m->size - m->count, num); + if (!len) + goto overflow; + m->count += len; + return 0; +overflow: + seq_set_overflow(m); + return -1; +} +EXPORT_SYMBOL(seq_put_decimal_ull); + +int seq_put_decimal_ll(struct seq_file *m, char delimiter, + long long num) +{ + if (num < 0) { + if (m->count + 3 >= m->size) { + seq_set_overflow(m); + return -1; + } + if (delimiter) + m->buf[m->count++] = delimiter; + num = -num; + delimiter = '-'; + } + return seq_put_decimal_ull(m, delimiter, num); + +} +EXPORT_SYMBOL(seq_put_decimal_ll); + +/** + * seq_write - write arbitrary data to buffer + * @seq: seq_file identifying the buffer to which data should be written + * @data: data address + * @len: number of bytes + * + * Return 0 on success, non-zero otherwise. + */ +int seq_write(struct seq_file *seq, const void *data, size_t len) +{ + if (seq->count + len < seq->size) { + memcpy(seq->buf + seq->count, data, len); + seq->count += len; + return 0; + } + seq_set_overflow(seq); + return -1; +} +EXPORT_SYMBOL(seq_write); + +/** + * seq_pad - write padding spaces to buffer + * @m: seq_file identifying the buffer to which data should be written + * @c: the byte to append after padding if non-zero + */ +void seq_pad(struct seq_file *m, char c) +{ + int size = m->pad_until - m->count; + if (size > 0) + seq_printf(m, "%*s", size, ""); + if (c) + seq_putc(m, c); +} +EXPORT_SYMBOL(seq_pad); + +struct list_head *seq_list_start(struct list_head *head, loff_t pos) +{ + struct list_head *lh; + + list_for_each(lh, head) + if (pos-- == 0) + return lh; + + return NULL; +} +EXPORT_SYMBOL(seq_list_start); + +struct list_head *seq_list_start_head(struct list_head *head, loff_t pos) +{ + if (!pos) + return head; + + return seq_list_start(head, pos - 1); +} +EXPORT_SYMBOL(seq_list_start_head); + +struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos) +{ + struct list_head *lh; + + lh = ((struct list_head *)v)->next; + ++*ppos; + return lh == head ? NULL : lh; +} +EXPORT_SYMBOL(seq_list_next); + +/** + * seq_hlist_start - start an iteration of a hlist + * @head: the head of the hlist + * @pos: the start position of the sequence + * + * Called at seq_file->op->start(). + */ +struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos) +{ + struct hlist_node *node; + + hlist_for_each(node, head) + if (pos-- == 0) + return node; + return NULL; +} +EXPORT_SYMBOL(seq_hlist_start); + +/** + * seq_hlist_start_head - start an iteration of a hlist + * @head: the head of the hlist + * @pos: the start position of the sequence + * + * Called at seq_file->op->start(). Call this function if you want to + * print a header at the top of the output. + */ +struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos) +{ + if (!pos) + return SEQ_START_TOKEN; + + return seq_hlist_start(head, pos - 1); +} +EXPORT_SYMBOL(seq_hlist_start_head); + +/** + * seq_hlist_next - move to the next position of the hlist + * @v: the current iterator + * @head: the head of the hlist + * @ppos: the current position + * + * Called at seq_file->op->next(). + */ +struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head, + loff_t *ppos) +{ + struct hlist_node *node = v; + + ++*ppos; + if (v == SEQ_START_TOKEN) + return head->first; + else + return node->next; +} +EXPORT_SYMBOL(seq_hlist_next); + +/** + * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU + * @head: the head of the hlist + * @pos: the start position of the sequence + * + * Called at seq_file->op->start(). + * + * This list-traversal primitive may safely run concurrently with + * the _rcu list-mutation primitives such as hlist_add_head_rcu() + * as long as the traversal is guarded by rcu_read_lock(). + */ +struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head, + loff_t pos) +{ + struct hlist_node *node; + + __hlist_for_each_rcu(node, head) + if (pos-- == 0) + return node; + return NULL; +} +EXPORT_SYMBOL(seq_hlist_start_rcu); + +/** + * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU + * @head: the head of the hlist + * @pos: the start position of the sequence + * + * Called at seq_file->op->start(). Call this function if you want to + * print a header at the top of the output. + * + * This list-traversal primitive may safely run concurrently with + * the _rcu list-mutation primitives such as hlist_add_head_rcu() + * as long as the traversal is guarded by rcu_read_lock(). + */ +struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head, + loff_t pos) +{ + if (!pos) + return SEQ_START_TOKEN; + + return seq_hlist_start_rcu(head, pos - 1); +} +EXPORT_SYMBOL(seq_hlist_start_head_rcu); + +/** + * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU + * @v: the current iterator + * @head: the head of the hlist + * @ppos: the current position + * + * Called at seq_file->op->next(). + * + * This list-traversal primitive may safely run concurrently with + * the _rcu list-mutation primitives such as hlist_add_head_rcu() + * as long as the traversal is guarded by rcu_read_lock(). + */ +struct hlist_node *seq_hlist_next_rcu(void *v, + struct hlist_head *head, + loff_t *ppos) +{ + struct hlist_node *node = v; + + ++*ppos; + if (v == SEQ_START_TOKEN) + return rcu_dereference(head->first); + else + return rcu_dereference(node->next); +} +EXPORT_SYMBOL(seq_hlist_next_rcu); + +/** + * seq_hlist_start_precpu - start an iteration of a percpu hlist array + * @head: pointer to percpu array of struct hlist_heads + * @cpu: pointer to cpu "cursor" + * @pos: start position of sequence + * + * Called at seq_file->op->start(). + */ +struct hlist_node * +seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos) +{ + struct hlist_node *node; + + for_each_possible_cpu(*cpu) { + hlist_for_each(node, per_cpu_ptr(head, *cpu)) { + if (pos-- == 0) + return node; + } + } + return NULL; +} +EXPORT_SYMBOL(seq_hlist_start_percpu); + +/** + * seq_hlist_next_percpu - move to the next position of the percpu hlist array + * @v: pointer to current hlist_node + * @head: pointer to percpu array of struct hlist_heads + * @cpu: pointer to cpu "cursor" + * @pos: start position of sequence + * + * Called at seq_file->op->next(). + */ +struct hlist_node * +seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head, + int *cpu, loff_t *pos) +{ + struct hlist_node *node = v; + + ++*pos; + + if (node->next) + return node->next; + + for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids; + *cpu = cpumask_next(*cpu, cpu_possible_mask)) { + struct hlist_head *bucket = per_cpu_ptr(head, *cpu); + + if (!hlist_empty(bucket)) + return bucket->first; + } + return NULL; +} +EXPORT_SYMBOL(seq_hlist_next_percpu); |