Re: [PATCH] open: O_DIRECTORY and O_CREAT together should fail

[Andrew Morton <akpm@osdl.org>]

Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> Add a check for O_DIRECTORY in the O_CREAT path, and return -EINVAL.
> 
> Current behavior is inconsistent with documentation: 
> open(..., O_DIRECTORY|O_CREAT) succeeds if file didn't exist, and
> returned descriptor does not refer to a directory.
> 
> No other error value quite fits this case: 
> 
>   ENOTDIR - the file doesn't exist, so this is slightly misleading
>   ENOENT - yes, but we asked for an O_CREAT so why wasn't it created
> 
> But EINVAL - invalid combination of flags, is quite good IMO.
> 

We could be a bit screwed here.  If there are any apps out there which are
using this combination, we just broke them.  Essentially the patch is
assuming that nobody is currently using O_CREAT|O_DIRECTORY, but one day in
the future someone will do that.


> 
> Index: linux/fs/namei.c
> ===================================================================
> --- linux.orig/fs/namei.c	2005-09-23 16:35:32.000000000 +0200
> +++ linux/fs/namei.c	2005-09-23 16:36:19.000000000 +0200
> @@ -1441,6 +1441,9 @@ int open_namei(const char * pathname, in
>  			return error;
>  		goto ok;
>  	}
> +	/* O_CREAT | O_DIRECTORY should fail */
> +	if (flag & O_DIRECTORY)
> +		return -EINVAL;
>  
>  	/*
>  	 * Create - we need to know the parent.