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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 now a supported feature, but currently only the ext2fs
* uses it. A count value of 1 is supported for compatibility with
* earlier libraries, but larger values are supported: count should
* indicate the total buffer space available for filling with dirents.
* The d_off entry in the dirents will then indicate the offset from
* each dirent to the next, and the return value will indicate the
* number of bytes written. All dirents will be written at
* word-aligned addresses. [sct Oct 1994]
*/
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->files->fd[fd]) ||
!(inode = file->f_inode))
return -EBADF;
error = -ENOTDIR;
if (file->f_op && file->f_op->readdir) {
int size = count;
if (count == 1)
size = sizeof(*dirent);
error = verify_area(VERIFY_WRITE, dirent, size);
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->files->fd[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;
if (tmp != file->f_pos) {
file->f_pos = tmp;
file->f_reada = 0;
file->f_version = ++event;
}
return file->f_pos;
}
asmlinkage int sys_llseek(unsigned int fd, unsigned long offset_high,
unsigned long offset_low, loff_t * result,
unsigned int origin)
{
struct file * file;
loff_t tmp = -1;
loff_t offset;
int err;
if (fd >= NR_OPEN || !(file=current->files->fd[fd]) || !(file->f_inode))
return -EBADF;
if (origin > 2)
return -EINVAL;
if ((err = verify_area(VERIFY_WRITE, result, sizeof(loff_t))))
return err;
offset = (loff_t) (((unsigned long long) offset_high << 32) | offset_low);
/* there is no fs specific llseek handler */
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;
file->f_version = ++event;
memcpy_tofs(result, &file->f_pos, sizeof(loff_t));
return 0;
}
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->files->fd[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;
int written;
if (fd>=NR_OPEN || !(file=current->files->fd[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;
written = file->f_op->write(inode,file,buf,count);
/*
* If data has been written to the file, remove the setuid and
* the setgid bits
*/
if (written > 0 && !suser() && (inode->i_mode & (S_ISUID | S_ISGID))) {
struct iattr newattrs;
newattrs.ia_mode = inode->i_mode & ~(S_ISUID | S_ISGID);
newattrs.ia_valid = ATTR_MODE;
notify_change(inode, &newattrs);
}
return written;
}
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