Re: [PATCH v2] AOSP: erofs-utils: fix sub-directory prefix for canned fs_config

[Yue Hu <zbestahu@gmail.com>]

On Mon, 28 Dec 2020 18:51:46 +0800
Gao Xiang <hsiangkao@redhat.com> wrote:

> From: Gao Xiang <hsiangkao@aol.com>
> 
> "failed to find [%s] in canned fs_config" was observed by using
> "--fs-config-file" option as reported by Yue Hu [1].
> 
> The root cause was that the mountpoint prefix to subdirectories is
> also needed if "--mount-point" presents. However, such prefix cannot
> be added by just using erofs_fspath().
> 
> One exception is that the root directory itself needs to be handled
> specially for canned fs_config. For such case, the prefix of the root
> directory has to be dropped instead.
> 
> [1]
> https://lkml.kernel.org/r/20201222020430.12512-1-zbestahu@gmail.com
> 
> Link:
> https://lore.kernel.org/r/20201226062736.29920-1-hsiangkao@aol.com
> Fixes: 8a9e8046f170 ("AOSP: erofs-utils: add fs_config support")
> Reported-by: Yue Hu <huyue2@yulong.com> Signed-off-by: Gao Xiang
> <hsiangkao@aol.com> ---
> changes since v2:
>  - fix IS_ROOT misuse reported by Jianan, very sorry about this since
>    I know little about canned fs_config.
> 
> (please kindly test again...)
> 
>  lib/inode.c | 39 +++++++++++++++++++++++++--------------
>  1 file changed, 25 insertions(+), 14 deletions(-)
> 
> diff --git a/lib/inode.c b/lib/inode.c
> index 0c4839d..e6159c9 100644
> --- a/lib/inode.c
> +++ b/lib/inode.c
> @@ -696,32 +696,43 @@ int erofs_droid_inode_fsconfig(struct
> erofs_inode *inode, /* filesystem_config does not preserve file type
> bits */ mode_t stat_file_type_mask = st->st_mode & S_IFMT;
>  	unsigned int uid = 0, gid = 0, mode = 0;
> -	char *fspath;
> +	const char *fspath;
> +	char *decorated = NULL;
>  
>  	inode->capabilities = 0;
> +	if (!cfg.fs_config_file && !cfg.mount_point)
> +		return 0;
> +
> +	if (!cfg.mount_point ||
> +	/* have to drop the mountpoint for rootdir of canned
> fsconfig */
> +	    (cfg.fs_config_file && erofs_fspath(path)[0] == '\0')) {
> +		fspath = erofs_fspath(path);
> +	} else {
> +		if (asprintf(&decorated, "%s/%s", cfg.mount_point,
> +			     erofs_fspath(path)) <= 0)
> +			return -ENOMEM;
> +		fspath = decorated;
> +	}
> +
>  	if (cfg.fs_config_file)

Whether we can use the first "cfg.fs_config_file" when loading canned
fs-config to reduce/simplify these duplicated calling?

> -		canned_fs_config(erofs_fspath(path),
> +		canned_fs_config(fspath,
>  				 S_ISDIR(st->st_mode),
>  				 cfg.target_out_path,
>  				 &uid, &gid, &mode,
> &inode->capabilities);
> -	else if (cfg.mount_point) {
> -		if (asprintf(&fspath, "%s/%s", cfg.mount_point,
> -			     erofs_fspath(path)) <= 0)
> -			return -ENOMEM;
> -
> +	else
>  		fs_config(fspath, S_ISDIR(st->st_mode),
>  			  cfg.target_out_path,
>  			  &uid, &gid, &mode, &inode->capabilities);
> -		free(fspath);
> -	}
> -	st->st_uid = uid;
> -	st->st_gid = gid;
> -	st->st_mode = mode | stat_file_type_mask;
>  
>  	erofs_dbg("/%s -> mode = 0x%x, uid = 0x%x, gid = 0x%x, "
>  		  "capabilities = 0x%" PRIx64 "\n",
> -		  erofs_fspath(path),
> -		  mode, uid, gid, inode->capabilities);
> +		  fspath, mode, uid, gid, inode->capabilities);
> +
> +	if (decorated)
> +		free(decorated);
> +	st->st_uid = uid;
> +	st->st_gid = gid;
> +	st->st_mode = mode | stat_file_type_mask;
>  	return 0;
>  }
>  #else