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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 <asm/segment.h>
/*
* Count is not yet used: but we'll probably support reading several entries
* at once in the future. Use count=1 in the library for future expansions.
*/
asmlinkage int sys_readdir(unsigned int fd, struct dirent * dirent, unsigned int count)
{
int error;
struct file * file;
struct inode * inode;
if (fd >= NR_OPEN || !(file = current->filp[fd]) ||
!(inode = file->f_inode))
return -EBADF;
error = -ENOTDIR;
if (file->f_op && file->f_op->readdir) {
error = verify_area(VERIFY_WRITE, dirent, sizeof (*dirent));
if (!error)
error = file->f_op->readdir(inode,file,dirent,count);
}
return error;
}
asmlinkage int sys_lseek(unsigned int fd, off_t offset, unsigned int origin)
{
struct file * file;
int tmp = -1;
if (fd >= NR_OPEN || !(file=current->filp[fd]) || !(file->f_inode))
return -EBADF;
if (origin > 2)
return -EINVAL;
if (file->f_op && file->f_op->lseek)
return file->f_op->lseek(file->f_inode,file,offset,origin);
/* this is the default handler if no lseek handler is present */
switch (origin) {
case 0:
tmp = offset;
break;
case 1:
tmp = file->f_pos + offset;
break;
case 2:
if (!file->f_inode)
return -EINVAL;
tmp = file->f_inode->i_size + offset;
break;
}
if (tmp < 0)
return -EINVAL;
file->f_pos = tmp;
file->f_reada = 0;
return file->f_pos;
}
asmlinkage int sys_read(unsigned int fd,char * buf,unsigned int count)
{
int error;
struct file * file;
struct inode * inode;
if (fd>=NR_OPEN || !(file=current->filp[fd]) || !(inode=file->f_inode))
return -EBADF;
if (!(file->f_mode & 1))
return -EBADF;
if (!file->f_op || !file->f_op->read)
return -EINVAL;
if (!count)
return 0;
error = verify_area(VERIFY_WRITE,buf,count);
if (error)
return error;
return file->f_op->read(inode,file,buf,count);
}
asmlinkage int sys_write(unsigned int fd,char * buf,unsigned int count)
{
int error;
struct file * file;
struct inode * inode;
if (fd>=NR_OPEN || !(file=current->filp[fd]) || !(inode=file->f_inode))
return -EBADF;
if (!(file->f_mode & 2))
return -EBADF;
if (!file->f_op || !file->f_op->write)
return -EINVAL;
if (!count)
return 0;
error = verify_area(VERIFY_READ,buf,count);
if (error)
return error;
return file->f_op->write(inode,file,buf,count);
}