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-rw-r--r--fs/seq_file.c440
1 files changed, 440 insertions, 0 deletions
diff --git a/fs/seq_file.c b/fs/seq_file.c
new file mode 100644
index 000000000000..650c43ba86c4
--- /dev/null
+++ b/fs/seq_file.c
@@ -0,0 +1,440 @@
+/*
+ * 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, @buf, @size, @ppos: see file_operations method
+ *
+ * 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, @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);
+ 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);
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-14 03:34:14 +0000