debugfs: Implement debugfs_create_str()

[linux-2.6-microblaze.git] / fs / debugfs / file.c

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 686e0ad..9b78e9e 100644 (file)
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -865,6 +865,97 @@ struct dentry *debugfs_create_bool(const char *name, umode_t mode,
 }
 EXPORT_SYMBOL_GPL(debugfs_create_bool);
 
+ssize_t debugfs_read_file_str(struct file *file, char __user *user_buf,
+                             size_t count, loff_t *ppos)
+{
+       struct dentry *dentry = F_DENTRY(file);
+       char *str, *copy = NULL;
+       int copy_len, len;
+       ssize_t ret;
+
+       ret = debugfs_file_get(dentry);
+       if (unlikely(ret))
+               return ret;
+
+       str = *(char **)file->private_data;
+       len = strlen(str) + 1;
+       copy = kmalloc(len, GFP_KERNEL);
+       if (!copy) {
+               debugfs_file_put(dentry);
+               return -ENOMEM;
+       }
+
+       copy_len = strscpy(copy, str, len);
+       debugfs_file_put(dentry);
+       if (copy_len < 0) {
+               kfree(copy);
+               return copy_len;
+       }
+
+       copy[copy_len] = '\n';
+
+       ret = simple_read_from_buffer(user_buf, count, ppos, copy, copy_len);
+       kfree(copy);
+
+       return ret;
+}
+
+static ssize_t debugfs_write_file_str(struct file *file, const char __user *user_buf,
+                                     size_t count, loff_t *ppos)
+{
+       /* This is really only for read-only strings */
+       return -EINVAL;
+}
+
+static const struct file_operations fops_str = {
+       .read =         debugfs_read_file_str,
+       .write =        debugfs_write_file_str,
+       .open =         simple_open,
+       .llseek =       default_llseek,
+};
+
+static const struct file_operations fops_str_ro = {
+       .read =         debugfs_read_file_str,
+       .open =         simple_open,
+       .llseek =       default_llseek,
+};
+
+static const struct file_operations fops_str_wo = {
+       .write =        debugfs_write_file_str,
+       .open =         simple_open,
+       .llseek =       default_llseek,
+};
+
+/**
+ * debugfs_create_str - create a debugfs file that is used to read and write a string value
+ * @name: a pointer to a string containing the name of the file to create.
+ * @mode: the permission that the file should have
+ * @parent: a pointer to the parent dentry for this file.  This should be a
+ *          directory dentry if set.  If this parameter is %NULL, then the
+ *          file will be created in the root of the debugfs filesystem.
+ * @value: a pointer to the variable that the file should read to and write
+ *         from.
+ *
+ * This function creates a file in debugfs with the given name that
+ * contains the value of the variable @value.  If the @mode variable is so
+ * set, it can be read from, and written to.
+ *
+ * This function will return a pointer to a dentry if it succeeds.  This
+ * pointer must be passed to the debugfs_remove() function when the file is
+ * to be removed (no automatic cleanup happens if your module is unloaded,
+ * you are responsible here.)  If an error occurs, ERR_PTR(-ERROR) will be
+ * returned.
+ *
+ * If debugfs is not enabled in the kernel, the value ERR_PTR(-ENODEV) will
+ * be returned.
+ */
+void debugfs_create_str(const char *name, umode_t mode,
+                       struct dentry *parent, char **value)
+{
+       debugfs_create_mode_unsafe(name, mode, parent, value, &fops_str,
+                                  &fops_str_ro, &fops_str_wo);
+}
+
 static ssize_t read_file_blob(struct file *file, char __user *user_buf,
                              size_t count, loff_t *ppos)
 {