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* linux/fs/read_write.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/stat.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/uio.h>
#include <linux/malloc.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <asm/uaccess.h>
static long long default_llseek(struct inode *inode,
struct file *file,
long long offset,
int origin)
{
long long retval;
switch (origin) {
case 2:
offset += inode->i_size;
break;
case 1:
offset += file->f_pos;
}
retval = -EINVAL;
if (offset >= 0) {
if (offset != file->f_pos) {
file->f_pos = offset;
file->f_reada = 0;
file->f_version = ++event;
}
retval = offset;
}
return retval;
}
static inline long long llseek(struct inode * inode, struct file *file,
long long offset, unsigned int origin)
{
long long (*fn)(struct inode *, struct file *, long long, int);
fn = default_llseek;
if (file->f_op && file->f_op->llseek)
fn = file->f_op->llseek;
return fn(inode, file, offset, origin);
}
asmlinkage long sys_lseek(unsigned int fd, off_t offset, unsigned int origin)
{
long retval;
struct file * file;
struct inode * inode;
lock_kernel();
retval = -EBADF;
if (fd >= NR_OPEN ||
!(file = current->files->fd[fd]) ||
!(inode = file->f_inode))
goto bad;
retval = -EINVAL;
if (origin > 2)
goto bad;
retval = llseek(inode, file, offset, origin);
bad:
unlock_kernel();
return retval;
}
asmlinkage int sys_llseek(unsigned int fd, unsigned long offset_high,
unsigned long offset_low, loff_t * result,
unsigned int origin)
{
long retval;
struct file * file;
struct inode * inode;
long long offset;
lock_kernel();
retval = -EBADF;
if (fd >= NR_OPEN ||
!(file = current->files->fd[fd]) ||
!(inode = file->f_inode))
goto bad;
retval = -EINVAL;
if (origin > 2)
goto bad;
offset = llseek(inode, file,
(((unsigned long long) offset_high << 32) | offset_low),
origin);
retval = offset;
if (offset >= 0) {
retval = copy_to_user(result, &offset, sizeof(offset));
if (retval)
retval = -EFAULT;
}
bad:
unlock_kernel();
return retval;
}
asmlinkage long sys_read(unsigned int fd, char * buf, unsigned long count)
{
int error;
struct file * file;
struct inode * inode;
long (*read)(struct inode *, struct file *, char *, unsigned long);
lock_kernel();
error = -EBADF;
file = fget(fd);
if (!file)
goto bad_file;
inode = file->f_inode;
if (!inode)
goto out;
error = -EBADF;
if (!(file->f_mode & 1))
goto out;
error = locks_verify_area(FLOCK_VERIFY_READ,inode,file,file->f_pos,count);
if (error)
goto out;
error = -EINVAL;
if (!file->f_op || !(read = file->f_op->read))
goto out;
error = read(inode,file,buf,count);
out:
fput(file, inode);
bad_file:
unlock_kernel();
return error;
}
asmlinkage long sys_write(unsigned int fd, const char * buf, unsigned long count)
{
int error;
struct file * file;
struct inode * inode;
long (*write)(struct inode *, struct file *, const char *, unsigned long);
lock_kernel();
error = -EBADF;
file = fget(fd);
if (!file)
goto bad_file;
inode = file->f_inode;
if (!inode)
goto out;
if (!(file->f_mode & 2))
goto out;
error = locks_verify_area(FLOCK_VERIFY_WRITE,inode,file,file->f_pos,count);
if (error)
goto out;
error = -EINVAL;
if (!file->f_op || !(write = file->f_op->write))
goto out;
down(&inode->i_sem);
error = write(inode,file,buf,count);
up(&inode->i_sem);
out:
fput(file, inode);
bad_file:
unlock_kernel();
return error;
}
typedef long (*IO_fn_t)(struct inode *, struct file *, char *, unsigned long);
static long do_readv_writev(int type, struct inode * inode, struct file * file,
const struct iovec * vector, unsigned long count)
{
unsigned long tot_len;
struct iovec iovstack[UIO_FASTIOV];
struct iovec *iov=iovstack;
long retval, i;
IO_fn_t fn;
/*
* First get the "struct iovec" from user memory and
* verify all the pointers
*/
if (!count)
return 0;
if (count > UIO_MAXIOV)
return -EINVAL;
if (count > UIO_FASTIOV) {
iov = kmalloc(count*sizeof(struct iovec), GFP_KERNEL);
if (!iov)
return -ENOMEM;
}
if (copy_from_user(iov, vector, count*sizeof(*vector))) {
if (iov != iovstack)
kfree(iov);
return -EFAULT;
}
tot_len = 0;
for (i = 0 ; i < count ; i++)
tot_len += iov[i].iov_len;
retval = locks_verify_area(type == VERIFY_READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE,
inode, file, file->f_pos, tot_len);
if (retval) {
if (iov != iovstack)
kfree(iov);
return retval;
}
/*
* Then do the actual IO. Note that sockets need to be handled
* specially as they have atomicity guarantees and can handle
* iovec's natively
*/
if (inode->i_sock) {
int err;
err = sock_readv_writev(type, inode, file, iov, count, tot_len);
if (iov != iovstack)
kfree(iov);
return err;
}
if (!file->f_op) {
if (iov != iovstack)
kfree(iov);
return -EINVAL;
}
/* VERIFY_WRITE actually means a read, as we write to user space */
fn = file->f_op->read;
if (type == VERIFY_READ)
fn = (IO_fn_t) file->f_op->write;
vector = iov;
while (count > 0) {
void * base;
int len, nr;
base = vector->iov_base;
len = vector->iov_len;
vector++;
count--;
nr = fn(inode, file, base, len);
if (nr < 0) {
if (retval)
break;
retval = nr;
break;
}
retval += nr;
if (nr != len)
break;
}
if (iov != iovstack)
kfree(iov);
return retval;
}
asmlinkage long sys_readv(unsigned long fd, const struct iovec * vector, unsigned long count)
{
struct file * file;
struct inode * inode;
long err = -EBADF;
lock_kernel();
if (fd >= NR_OPEN || !(file = current->files->fd[fd]) || !(inode=file->f_inode))
goto out;
if (!(file->f_mode & 1))
goto out;
err = do_readv_writev(VERIFY_WRITE, inode, file, vector, count);
out:
unlock_kernel();
return err;
}
asmlinkage long sys_writev(unsigned long fd, const struct iovec * vector, unsigned long count)
{
int error = -EBADF;
struct file * file;
struct inode * inode;
lock_kernel();
if (fd >= NR_OPEN || !(file = current->files->fd[fd]) || !(inode=file->f_inode))
goto out;
if (!(file->f_mode & 2))
goto out;
down(&inode->i_sem);
error = do_readv_writev(VERIFY_READ, inode, file, vector, count);
up(&inode->i_sem);
out:
unlock_kernel();
return error;
}
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