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);