On Mon, 12 Jul 2010, Aneesh Kumar K.V wrote:
> From: NeilBrown <neilb@xxxxxxx>
>
> This enables to use readlink to get the link target name
> from a file descriptor point to the link. This can be used
> with open_by_handle syscall that returns a file descriptor for a link.
> We can then use this file descriptor to get the target name.
>
> This is similar to utimensat(2) interface
We could introduce pair of new helper functions to extract the common
code from do_utimes() and this:
err = lookup_path_at(dfd, filename, atflags, &path, &file);
/* do something with path */
put_path_at(&path, file);
Thanks,
Miklos
> Signed-off-by: NeilBrown <neilb@xxxxxxx>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> ---
> fs/stat.c | 30 ++++++++++++++++++++++--------
> 1 files changed, 22 insertions(+), 8 deletions(-)
>
> diff --git a/fs/stat.c b/fs/stat.c
> index c4ecd52..a66a0ef 100644
> --- a/fs/stat.c
> +++ b/fs/stat.c
> @@ -284,26 +284,40 @@ SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf)
> SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
> char __user *, buf, int, bufsiz)
> {
> - struct path path;
> - int error;
> + int error = 0, fput_needed;
> + struct path path, *pp;
> + struct file *file = NULL;
>
> if (bufsiz <= 0)
> return -EINVAL;
>
> - error = user_path_at(dfd, pathname, 0, &path);
> + if (pathname == NULL && dfd != AT_FDCWD) {
> + file = fget_light(dfd, &fput_needed);
> +
> + if (file)
> + pp = &file->f_path;
> + else
> + error = -EBADF;
> + } else {
> + error = user_path_at(dfd, pathname, 0, &path);
> + pp = &path;
> + }
> if (!error) {
> - struct inode *inode = path.dentry->d_inode;
> + struct inode *inode = pp->dentry->d_inode;
>
> error = -EINVAL;
> if (inode->i_op->readlink) {
> - error = security_inode_readlink(path.dentry);
> + error = security_inode_readlink(pp->dentry);
> if (!error) {
> - touch_atime(path.mnt, path.dentry);
> - error = inode->i_op->readlink(path.dentry,
> + touch_atime(pp->mnt, pp->dentry);
> + error = inode->i_op->readlink(pp->dentry,
> buf, bufsiz);
> }
> }
> - path_put(&path);
> + if (file)
> + fput_light(file, fput_needed);
> + else
> + path_put(&path);
> }
> return error;
> }
> --
> 1.7.2.rc1
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
