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/kernel.h>
  14 #include <linux/kobject.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17
  18 #include <asm/uaccess.h>
  19 #include <asm/semaphore.h>
  20
  21 #include "sysfs.h"
  22
  23 static int
  24 fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
  25 {
  26         struct bin_attribute * attr = to_bin_attr(dentry);
  27         struct kobject * kobj = to_kobj(dentry->d_parent);
  28
  29         if (!attr->read)
  30                 return -EIO;
  31
  32         return attr->read(kobj, buffer, off, count);
  33 }
  34
  35 static ssize_t
  36 read(struct file * file, char __user * userbuf, size_t count, loff_t * off)
  37 {
  38         char *buffer = file->private_data;
  39         struct dentry *dentry = file->f_path.dentry;
  40         int size = dentry->d_inode->i_size;
  41         loff_t offs = *off;
  42         int ret;
  43
  44         if (count > PAGE_SIZE)
  45                 count = PAGE_SIZE;
  46
  47         if (size) {
  48                 if (offs > size)
  49                         return 0;
  50                 if (offs + count > size)
  51                         count = size - offs;
  52         }
  53
  54         ret = fill_read(dentry, buffer, offs, count);
  55         if (ret < 0)
  56                 return ret;
  57         count = ret;
  58
  59         if (copy_to_user(userbuf, buffer, count))
  60                 return -EFAULT;
  61
  62         pr_debug("offs = %lld, *off = %lld, count = %zd\n", offs, *off, count);
  63
  64         *off = offs + count;
  65
  66         return count;
  67 }
  68
  69 static int
  70 flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
  71 {
  72         struct bin_attribute *attr = to_bin_attr(dentry);
  73         struct kobject *kobj = to_kobj(dentry->d_parent);
  74
  75         if (!attr->write)
  76                 return -EIO;
  77
  78         return attr->write(kobj, buffer, offset, count);
  79 }
  80
  81 static ssize_t write(struct file * file, const char __user * userbuf,
  82                      size_t count, loff_t * off)
  83 {
  84         char *buffer = file->private_data;
  85         struct dentry *dentry = file->f_path.dentry;
  86         int size = dentry->d_inode->i_size;
  87         loff_t offs = *off;
  88
  89         if (count > PAGE_SIZE)
  90                 count = PAGE_SIZE;
  91         if (size) {
  92                 if (offs > size)
  93                         return 0;
  94                 if (offs + count > size)
  95                         count = size - offs;
  96         }
  97
  98         if (copy_from_user(buffer, userbuf, count))
  99                 return -EFAULT;
 100
 101         count = flush_write(dentry, buffer, offs, count);
 102         if (count > 0)
 103                 *off = offs + count;
 104         return count;
 105 }
 106
 107 static int mmap(struct file *file, struct vm_area_struct *vma)
 108 {
 109         struct dentry *dentry = file->f_path.dentry;
 110         struct bin_attribute *attr = to_bin_attr(dentry);
 111         struct kobject *kobj = to_kobj(dentry->d_parent);
 112
 113         if (!attr->mmap)
 114                 return -EINVAL;
 115
 116         return attr->mmap(kobj, attr, vma);
 117 }
 118
 119 static int open(struct inode * inode, struct file * file)
 120 {
 121         struct kobject *kobj = sysfs_get_kobject(file->f_path.dentry->d_parent);
 122         struct bin_attribute * attr = to_bin_attr(file->f_path.dentry);
 123         int error = -EINVAL;
 124
 125         if (!kobj || !attr)
 126                 goto Done;
 127
 128         /* Grab the module reference for this attribute if we have one */
 129         error = -ENODEV;
 130         if (!try_module_get(attr->attr.owner))
 131                 goto Done;
 132
 133         error = -EACCES;
 134         if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
 135                 goto Error;
 136         if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
 137                 goto Error;
 138
 139         error = -ENOMEM;
 140         file->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
 141         if (!file->private_data)
 142                 goto Error;
 143
 144         error = 0;
 145     goto Done;
 146
 147  Error:
 148         module_put(attr->attr.owner);
 149  Done:
 150         if (error)
 151                 kobject_put(kobj);
 152         return error;
 153 }
 154
 155 static int release(struct inode * inode, struct file * file)
 156 {
 157         struct kobject * kobj = to_kobj(file->f_path.dentry->d_parent);
 158         struct bin_attribute * attr = to_bin_attr(file->f_path.dentry);
 159         u8 * buffer = file->private_data;
 160
 161         kobject_put(kobj);
 162         module_put(attr->attr.owner);
 163         kfree(buffer);
 164         return 0;
 165 }
 166
 167 const struct file_operations bin_fops = {
 168         .read           = read,
 169         .write          = write,
 170         .mmap           = mmap,
 171         .llseek         = generic_file_llseek,
 172         .open           = open,
 173         .release        = release,
 174 };
 175
 176 /**
 177  *      sysfs_create_bin_file - create binary file for object.
 178  *      @kobj:  object.
 179  *      @attr:  attribute descriptor.
 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 void sysfs_remove_bin_file(struct kobject * kobj, struct bin_attribute * attr)
 197 {
 198         if (sysfs_hash_and_remove(kobj->dentry, attr->attr.name) < 0) {
 199                 printk(KERN_ERR "%s: "
 200                         "bad dentry or inode or no such file: \"%s\"\n",
 201                         __FUNCTION__, attr->attr.name);
 202                 dump_stack();
 203         }
 204 }
 205
 206 EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
 207 EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);