fs/sysfs/bin.c

   1 /*
   2  * bin.c - binary file operations for sysfs.
   3  *
   4  * Copyright (c) 2003 Patrick Mochel
   5  * Copyright (c) 2003 Matthew Wilcox
   6  * Copyright (c) 2004 Silicon Graphics, Inc.
   7  */
   8
   9 #undef DEBUG
  10
  11 #include <linux/errno.h>
  12 #include <linux/fs.h>
  13 #include <linux/kobject.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16
  17 #include <asm/uaccess.h>
  18
  19 #include "sysfs.h"
  20
  21 static int
  22 fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
  23 {
  24         struct bin_attribute * attr = to_bin_attr(dentry);
  25         struct kobject * kobj = to_kobj(dentry->d_parent);
  26
  27         if (!attr->read)
  28                 return -EIO;
  29
  30         return attr->read(kobj, buffer, off, count);
  31 }
  32
  33 static ssize_t
  34 read(struct file * file, char __user * userbuf, size_t count, loff_t * off)
  35 {
  36         char *buffer = file->private_data;
  37         struct dentry *dentry = file->f_dentry;
  38         int size = dentry->d_inode->i_size;
  39         loff_t offs = *off;
  40         int ret;
  41
  42         if (count > PAGE_SIZE)
  43                 count = PAGE_SIZE;
  44
  45         if (size) {
  46                 if (offs > size)
  47                         return 0;
  48                 if (offs + count > size)
  49                         count = size - offs;
  50         }
  51
  52         ret = fill_read(dentry, buffer, offs, count);
  53         if (ret < 0)
  54                 return ret;
  55         count = ret;
  56
  57         if (copy_to_user(userbuf, buffer, count))
  58                 return -EFAULT;
  59
  60         pr_debug("offs = %lld, *off = %lld, count = %zd\n", offs, *off, count);
  61
  62         *off = offs + count;
  63
  64         return count;
  65 }
  66
  67 static int
  68 flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
  69 {
  70         struct bin_attribute *attr = to_bin_attr(dentry);
  71         struct kobject *kobj = to_kobj(dentry->d_parent);
  72
  73         if (!attr->write)
  74                 return -EIO;
  75
  76         return attr->write(kobj, buffer, offset, count);
  77 }
  78
  79 static ssize_t write(struct file * file, const char __user * userbuf,
  80                      size_t count, loff_t * off)
  81 {
  82         char *buffer = file->private_data;
  83         struct dentry *dentry = file->f_dentry;
  84         int size = dentry->d_inode->i_size;
  85         loff_t offs = *off;
  86
  87         if (count > PAGE_SIZE)
  88                 count = PAGE_SIZE;
  89         if (size) {
  90                 if (offs > size)
  91                         return 0;
  92                 if (offs + count > size)
  93                         count = size - offs;
  94         }
  95
  96         if (copy_from_user(buffer, userbuf, count))
  97                 return -EFAULT;
  98
  99         count = flush_write(dentry, buffer, offs, count);
 100         if (count > 0)
 101                 *off = offs + count;
 102         return count;
 103 }
 104
 105 static int mmap(struct file *file, struct vm_area_struct *vma)
 106 {
 107         struct dentry *dentry = file->f_dentry;
 108         struct bin_attribute *attr = to_bin_attr(dentry);
 109         struct kobject *kobj = to_kobj(dentry->d_parent);
 110
 111         if (!attr->mmap)
 112                 return -EINVAL;
 113
 114         return attr->mmap(kobj, attr, vma);
 115 }
 116
 117 static int open(struct inode * inode, struct file * file)
 118 {
 119         struct kobject *kobj = sysfs_get_kobject(file->f_dentry->d_parent);
 120         struct bin_attribute * attr = to_bin_attr(file->f_dentry);
 121         int error = -EINVAL;
 122
 123         if (!kobj || !attr)
 124                 goto Done;
 125
 126         /* Grab the module reference for this attribute if we have one */
 127         error = -ENODEV;
 128         if (!try_module_get(attr->attr.owner))
 129                 goto Done;
 130
 131         error = -EACCES;
 132         if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
 133                 goto Error;
 134         if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
 135                 goto Error;
 136
 137         error = -ENOMEM;
 138         file->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
 139         if (!file->private_data)
 140                 goto Error;
 141
 142         error = 0;
 143     goto Done;
 144
 145  Error:
 146         module_put(attr->attr.owner);
 147  Done:
 148         if (error && kobj)
 149                 kobject_put(kobj);
 150         return error;
 151 }
 152
 153 static int release(struct inode * inode, struct file * file)
 154 {
 155         struct kobject * kobj = to_kobj(file->f_dentry->d_parent);
 156         struct bin_attribute * attr = to_bin_attr(file->f_dentry);
 157         u8 * buffer = file->private_data;
 158
 159         if (kobj)
 160                 kobject_put(kobj);
 161         module_put(attr->attr.owner);
 162         kfree(buffer);
 163         return 0;
 164 }
 165
 166 const struct file_operations bin_fops = {
 167         .read           = read,
 168         .write          = write,
 169         .mmap           = mmap,
 170         .llseek         = generic_file_llseek,
 171         .open           = open,
 172         .release        = release,
 173 };
 174
 175 /**
 176  *      sysfs_create_bin_file - create binary file for object.
 177  *      @kobj:  object.
 178  *      @attr:  attribute descriptor.
 179  *
 180  */
 181
 182 int sysfs_create_bin_file(struct kobject * kobj, struct bin_attribute * attr)
 183 {
 184         BUG_ON(!kobj || !kobj->dentry || !attr);
 185
 186         return sysfs_add_file(kobj->dentry, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
 187 }
 188
 189
 190 /**
 191  *      sysfs_remove_bin_file - remove binary file for object.
 192  *      @kobj:  object.
 193  *      @attr:  attribute descriptor.
 194  *
 195  */
 196
 197 int sysfs_remove_bin_file(struct kobject * kobj, struct bin_attribute * attr)
 198 {
 199         sysfs_hash_and_remove(kobj->dentry,attr->attr.name);
 200         return 0;
 201 }
 202
 203 EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
 204 EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);