/*
* linux/fs/read_write.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/uio.h>
#include <linux/fsnotify.h>
#include <linux/security.h>
#include <linux/module.h>
#include <linux/syscalls.h>
#include <linux/pagemap.h>
#include <linux/splice.h>
#include "read_write.h"
#include <asm/uaccess.h>
#include <asm/unistd.h>
const struct file_operations generic_ro_fops = {
.llseek = generic_file_llseek,
.read = do_sync_read,
.aio_read = generic_file_aio_read,
.mmap = generic_file_readonly_mmap,
.splice_read = generic_file_splice_read,
};
EXPORT_SYMBOL(generic_ro_fops);
static inline int unsigned_offsets(struct file *file)
{
return file->f_mode & FMODE_UNSIGNED_OFFSET;
}
/**
* generic_file_llseek_unlocked - lockless generic llseek implementation
* @file: file structure to seek on
* @offset: file offset to seek to
* @origin: type of seek
*
* Updates the file offset to the value specified by @offset and @origin.
* Locking must be provided by the caller.
*/
loff_t
generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin)
{
struct inode *inode = file->f_mapping->host;
switch (origin) {
case SEEK_END:
offset += inode->i_size;
break;
case SEEK_CUR:
/*
* Here we special-case the lseek(fd, 0, SEEK_CUR)
* position-querying operation. Avoid rewriting the "same"
* f_pos value back to the file because a concurrent read(),
* write() or lseek() might have altered it
*/
if (offset == 0)
return file->f_pos;
offset += file->f_pos;
break;
}
if (offset < 0 && !unsigned_offsets(file))
return -EINVAL;
if (offset > inode->i_sb->s_maxbytes)
return -EINVAL;
/* Special lock needed here? */
if (offset != file->f_pos) {
file->f_pos = offset;
file->f_version = 0;
}
return offset;
}
EXPORT_SYMBOL(generic_file_llseek_unlocked);
/**
* generic_file_llseek - generic llseek implementation for regular files
* @file: file structure to seek on
* @offset: file offset to seek to
* @origin: type of seek
*
* This is a generic implemenation of ->llseek useable for all normal local
* filesystems. It just updates the file offset to the value specified by
* @offset and @origin under i_mutex.
*/
loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
{
loff_t rval;
mutex_lock(&file->f_dentry->d_inode->i_mutex);
rval = generic_file_llseek_unlocked(file, offset, origin);
mutex_unlock(&file->f_dentry->d_inode->i_mutex);
return rval;
}
EXPORT_SYMBOL(generic_file_llseek);
/**
* noop_llseek - No Operation Performed llseek implementation
* @file: file structure to seek on
* @offset: file offset to seek to
* @origin: type of seek
*
* This is an implementation of ->llseek useable for the rare special case when
* userspace expects the seek to succeed but the (device) file is actually not
* able to perform the seek. In this case you use noop_llseek() instead of
* falling back to the default implementation of ->llseek.
*/
loff_t noop_llseek(struct file *file, loff_t offset, int origin)
{
return file->f_pos;
}
EXPORT_SYMBOL(noop_llseek);
loff_t no_llseek(struct file *file, loff_t offset, int origin)
{
return -ESPIPE;
}
EXPORT_SYMBOL(no_llseek);
loff_t default_llseek(struct file *file, loff_t offset, int origin)
{
loff_t retval;
mutex_lock(&file->f_dentry->d_inode->i_mutex);
switch (origin) {
case SEEK_END:
offset += i_size_read(file->f_path.dentry->d_inode);
break;
case SEEK_CUR:
if (offset == 0) {
retval = file->f_pos;
goto out;
}
offset += file->f_pos;
}
retval = -EINVAL;
if (offset >= 0 || unsigned_offsets(file)) {
if (offset != file->f_pos) {
file->f_pos = offset;
file->f_version = 0;
}
retval = offset;
}
out:
mutex_unlock(&file->f_dentry->d_inode->i_mutex);
return retval;
}
EXPORT_SYMBOL(default_llseek);
loff_t vfs_llseek(struct file *file, loff_t offset, int origin)
{
loff_t (*fn)(struct file *, loff_t, int);
fn = no_llseek;
if (file->f_mode & FMODE_LSEEK) {
if (file->f_op && file->f_op->llseek)
fn = file->f_op->llseek;
}
return fn(file, offset, origin);
}
EXPORT_SYMBOL(vfs_llseek);
SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, origin)
{
off_t retval;
struct file * file;
int fput_needed;
retval = -EBADF;
file = fget_light(fd, &fput_needed);
if (