root/fs/sysfs/bin.c

DEFINITIONS

1. fill_read
2. read
3. flush_write
4. write
5. mmap
6. open
7. release
8. sysfs_create_bin_file
9. sysfs_remove_bin_file

/*
 * fs/sysfs/bin.c - sysfs binary file implementation
 *
 * Copyright (c) 2003 Patrick Mochel
 * Copyright (c) 2003 Matthew Wilcox
 * Copyright (c) 2004 Silicon Graphics, Inc.
 * Copyright (c) 2007 SUSE Linux Products GmbH
 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
 *
 * This file is released under the GPLv2.
 *
 * Please see Documentation/filesystems/sysfs.txt for more information.
 */

#undef DEBUG

#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mutex.h>

#include <asm/uaccess.h>

#include "sysfs.h"

struct bin_buffer {
        struct mutex    mutex;
        void            *buffer;
        int             mmapped;
};

static int
fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
{
        struct sysfs_dirent *attr_sd = dentry->d_fsdata;
        struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
        struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
        int rc;

        /* need attr_sd for attr, its parent for kobj */
        if (!sysfs_get_active_two(attr_sd))
                return -ENODEV;

        rc = -EIO;
        if (attr->read)
                rc = attr->read(kobj, attr, buffer, off, count);

        sysfs_put_active_two(attr_sd);

        return rc;
}

static ssize_t
read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
{
        struct bin_buffer *bb = file->private_data;
        struct dentry *dentry = file->f_path.dentry;
        int size = dentry->d_inode->i_size;
        loff_t offs = *off;
        int count = min_t(size_t, bytes, PAGE_SIZE);

        if (size) {
                if (offs > size)
                        return 0;
                if (offs + count > size)
                        count = size - offs;
        }

        mutex_lock(&bb->mutex);

        count = fill_read(dentry, bb->buffer, offs, count);
        if (count < 0)
                goto out_unlock;

        if (copy_to_user(userbuf, bb->buffer, count)) {
                count = -EFAULT;
                goto out_unlock;
        }

        pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);

        *off = offs + count;

 out_unlock:
        mutex_unlock(&bb->mutex);
        return count;
}

static int
flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
{
        struct sysfs_dirent *attr_sd = dentry->d_fsdata;
        struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
        struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
        int rc;

        /* need attr_sd for attr, its parent for kobj */
        if (!sysfs_get_active_two(attr_sd))
                return -ENODEV;

        rc = -EIO;
        if (attr->write)
                rc = attr->write(kobj, attr, buffer, offset, count);

        sysfs_put_active_two(attr_sd);

        return rc;
}

static ssize_t write(struct file *file, const char __user *userbuf,
                     size_t bytes, loff_t *off)
{
        struct bin_buffer *bb = file->private_data;
        struct dentry *dentry = file->f_path.dentry;
        int size = dentry->d_inode->i_size;
        loff_t offs = *off;
        int count = min_t(size_t, bytes, PAGE_SIZE);

        if (size) {
                if (offs > size)
                        return 0;
                if (offs + count > size)
                        count = size - offs;
        }

        mutex_lock(&bb->mutex);

        if (copy_from_user(bb->buffer, userbuf, count)) {
                count = -EFAULT;
                goto out_unlock;
        }

        count = flush_write(dentry, bb->buffer, offs, count);
        if (count > 0)
                *off = offs + count;

 out_unlock:
        mutex_unlock(&bb->mutex);
        return count;
}

static int mmap(struct file *file, struct vm_area_struct *vma)
{
        struct bin_buffer *bb = file->private_data;
        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
        struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
        struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
        int rc;

        mutex_lock(&bb->mutex);

        /* need attr_sd for attr, its parent for kobj */
        if (!sysfs_get_active_two(attr_sd))
                return -ENODEV;

        rc = -EINVAL;
        if (attr->mmap)
                rc = attr->mmap(kobj, attr, vma);

        if (rc == 0 && !bb->mmapped)
                bb->mmapped = 1;
        else
                sysfs_put_active_two(attr_sd);

        mutex_unlock(&bb->mutex);

        return rc;
}

static int open(struct inode * inode, struct file * file)
{
        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
        struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
        struct bin_buffer *bb = NULL;
        int error;

        /* binary file operations requires both @sd and its parent */
        if (!sysfs_get_active_two(attr_sd))
                return -ENODEV;

        error = -EACCES;
        if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
                goto err_out;
        if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
                goto err_out;

        error = -ENOMEM;
        bb = kzalloc(sizeof(*bb), GFP_KERNEL);
        if (!bb)
                goto err_out;

        bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
        if (!bb->buffer)
                goto err_out;

        mutex_init(&bb->mutex);
        file->private_data = bb;

        /* open succeeded, put active references */
        sysfs_put_active_two(attr_sd);
        return 0;

 err_out:
        sysfs_put_active_two(attr_sd);
        kfree(bb);
        return error;
}

static int release(struct inode * inode, struct file * file)
{
        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
        struct bin_buffer *bb = file->private_data;

        if (bb->mmapped)
                sysfs_put_active_two(attr_sd);
        kfree(bb->buffer);
        kfree(bb);
        return 0;
}

const struct file_operations bin_fops = {
        .read           = read,
        .write          = write,
        .mmap           = mmap,
        .llseek         = generic_file_llseek,
        .open           = open,
        .release        = release,
};

/**
 *      sysfs_create_bin_file - create binary file for object.
 *      @kobj:  object.
 *      @attr:  attribute descriptor.
 */

int sysfs_create_bin_file(struct kobject * kobj, struct bin_attribute * attr)
{
        BUG_ON(!kobj || !kobj->sd || !attr);

        return sysfs_add_file(kobj->sd, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
}


/**
 *      sysfs_remove_bin_file - remove binary file for object.
 *      @kobj:  object.
 *      @attr:  attribute descriptor.
 */

void sysfs_remove_bin_file(struct kobject * kobj, struct bin_attribute * attr)
{
        sysfs_hash_and_remove(kobj->sd, attr->attr.name);
}

EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);