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// SPDX-License-Identifier: GPL-2.0
/*
* fs/sysfs/file.c - sysfs regular (text) file implementation
*
* Copyright (c) 2001-3 Patrick Mochel
* Copyright (c) 2007 SUSE Linux Products GmbH
* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
*
* Please see Documentation/filesystems/sysfs.txt for more information.
*/
#include <linux/module.h>
#include <linux/kobject.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/seq_file.h>
#include "sysfs.h"
#include "../kernfs/kernfs-internal.h"
/*
* Determine ktype->sysfs_ops for the given kernfs_node. This function
* must be called while holding an active reference.
*/
static const struct sysfs_ops *sysfs_file_ops(struct kernfs_node *kn)
{
struct kobject *kobj = kn->parent->priv;
if (kn->flags & KERNFS_LOCKDEP)
lockdep_assert_held(kn);
return kobj->ktype ? kobj->ktype->sysfs_ops : NULL;
}
/*
* Reads on sysfs are handled through seq_file, which takes care of hairy
* details like buffering and seeking. The following function pipes
* sysfs_ops->show() result through seq_file.
*/
static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
{
struct kernfs_open_file *of = sf->private;
struct kobject *kobj = of->kn->parent->priv;
const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
ssize_t count;
char *buf;
/* acquire buffer and ensure that it's >= PAGE_SIZE and clear */
count = seq_get_buf(sf, &buf);
if (count < PAGE_SIZE) {
seq_commit(sf, -1);
return 0;
}
memset(buf, 0, PAGE_SIZE);
/*
* Invoke show(). Control may reach here via seq file lseek even
* if @ops->show() isn't implemented.
*/
if (ops->show) {
count = ops->show(kobj, of->kn->priv, buf);
if (count < 0)
return count;
}
/*
* The code works fine with PAGE_SIZE return but it's likely to
* indicate truncated result or overflow in normal use cases.
*/
if (count >= (ssize_t)PAGE_SIZE) {
printk("fill_read_buffer: %pS returned bad count\n",
ops->show);
/* Try to struggle along */
count = PAGE_SIZE - 1;
}
seq_commit(sf, count);
return 0;
}
static ssize_t sysfs_kf_bin_read(struct kernfs_open_file *of, char *buf,
size_t count, loff_t pos)
{
struct bin_attribute *battr = of->kn->priv;
struct kobject *kobj = of->kn->parent->priv;
loff_t size = file_inode(of->file)->i_size;
if (!count)
return 0;
if (size) {
if (pos >= size)
return 0;
if (pos + count > size)
count = size - pos;
}
if (!battr->read)
return -EIO;
return battr->read(of->file, kobj, battr, buf, pos, count);
}
/* kernfs read callback for regular sysfs files with pre-alloc */
static ssize_t sysfs_kf_read(struct kernfs_open_file *of, char *buf,
size_t count, loff_t pos)
{
const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
struct kobject *kobj = of->kn->parent->priv;
ssize_t len;
/*
* If buf != of->prealloc_buf, we don't know how
* large it is, so cannot safely pass it to ->show
*/
if (WARN_ON_ONCE(buf != of->prealloc_buf))
return 0;
len = ops->show(kobj, of->kn->priv, buf);
if (len < 0)
return len;
if (pos) {
if (len <= pos)
return 0;
len -= pos;
memmove(buf, buf + pos, len);
}
return min_t(ssize_t, count, len);
}
/* kernfs write callback for regular sysfs files */
static ssize_t sysfs_kf_write(struct kernfs_open_file *of, char *buf,
size_t count, loff_t pos)
{
const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
struct kobject *kobj = of->kn->parent->priv;
if (!count)
return 0;
return ops->store(kobj, of->kn->priv, buf, count);
}
/* kernfs write callback for bin sysfs files */
static ssize_t sysfs_kf_bin_write(struct kernfs_open_file *of, char *buf,
size_t count, loff_t pos)
{
struct bin_attribute *battr = of->kn->priv;
struct kobject *kobj = of->kn->parent->priv;
loff_t size = file_inode(of->file)->i_size;
if (size) {
if (size <= pos)
return -EFBIG;
count = min_t(ssize_t, count, size - pos);
}
if (!count)
return 0;
if (!battr->write)
return -EIO;
return battr->write(of->file, kobj, battr, buf, pos, count);
}
static int sysfs_kf_bin_mmap(struct kernfs_open_file *of,
struct vm_area_struct *vma)
{
struct bin_attribute *battr = of->kn->priv;
struct kobject *kobj = of->kn->parent->priv;
return battr->mmap(of->file, kobj, battr, vma);
}
void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr)
{
struct kernfs_node *kn = kobj->sd, *tmp;
if (kn && dir)
kn = kernfs_find_and_get(kn, dir);
else
kernfs_get(kn);
if (kn && attr) {
tmp = kernfs_find_and_get(kn, attr);
kernfs_put(kn);
kn = tmp;
}
if (kn) {
kernfs_notify(kn);
kernfs_put(kn);
}
}
EXPORT_SYMBOL_GPL(sysfs_notify);
static const struct kernfs_ops sysfs_file_kfops_empty = {
};
static const struct kernfs_ops sysfs_file_kfops_ro = {
.seq_show = sysfs_kf_seq_show,
};
static const struct kernfs_ops sysfs_file_kfops_wo = {
.write = sysfs_kf_write,
};
static const struct kernfs_ops sysfs_file_kfops_rw = {
.seq_show = sysfs_kf_seq_show,
.write = sysfs_kf_write,
};
static const struct kernfs_ops sysfs_prealloc_kfops_ro = {
.read = sysfs_kf_read,
.prealloc = true,
};
static const struct kernfs_ops sysfs_prealloc_kfops_wo = {
.write = sysfs_kf_write,
.prealloc = true,
};
static const struct kernfs_ops sysfs_prealloc_kfops_rw = {
.read = sysfs_kf_read,
.write = sysfs_kf_write,
.prealloc = true,
};
static const struct kernfs_ops sysfs_bin_kfops_ro = {
.read = sysfs_kf_bin_read,
};
static const struct kernfs_ops sysfs_bin_kfops_wo = {
.write = sysfs_kf_bin_write,
};
static const struct kernfs_ops sysfs_bin_k
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