[PATCH 1/1] ext4: detect directories in ext4fs_exists()

[Caleb Connolly]

On 20/02/2024 11:54, Heinrich Schuchardt wrote:
> While fat_exists() reports directories and files as existing
> ext4fs_exists() only recognizes files. This lead to errors
> when using systemd-boot with an ext4 file-system.
> 
> Change ext4fs_exists() to find any type of inode:
> files, directories, symbolic links.
> 
> Fixes: a1596438a689 ("ext4fs ls load support")
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>

This doesn't entirely fix systemd-boot, the fs_get_size() call still
winds up in ext4fs_open() which fails because it's a directory...

I poked around to see if I could get this working but it seems like it
won't be simple :/

This is still a valid bugfix though, even if it doesn't totally fix the
issue.

Reviwed-by: Caleb Connolly <caleb.connolly at linaro.org>
> ---
> I still need to figure out a good test. Currently 'xxd' is the only command
> invoking fs_exists().
> ---
>  fs/ext4/ext4_common.c |  5 ++---
>  fs/ext4/ext4_common.h |  2 ++
>  fs/ext4/ext4fs.c      | 11 +++++++----
>  3 files changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
> index ea9b92298ba..365c5147c4b 100644
> --- a/fs/ext4/ext4_common.c
> +++ b/fs/ext4/ext4_common.c
> @@ -2214,9 +2214,8 @@ static char *ext4fs_read_symlink(struct ext2fs_node *node)
>  	return symlink;
>  }
>  
> -static int ext4fs_find_file1(const char *currpath,
> -			     struct ext2fs_node *currroot,
> -			     struct ext2fs_node **currfound, int *foundtype)
> +int ext4fs_find_file1(const char *currpath, struct ext2fs_node *currroot,
> +		      struct ext2fs_node **currfound, int *foundtype)
>  {
>  	char fpath[strlen(currpath) + 1];
>  	char *name = fpath;
> diff --git a/fs/ext4/ext4_common.h b/fs/ext4/ext4_common.h
> index 504c708b064..84500e990aa 100644
> --- a/fs/ext4/ext4_common.h
> +++ b/fs/ext4/ext4_common.h
> @@ -54,6 +54,8 @@ int ext4fs_read_file(struct ext2fs_node *node, loff_t pos, loff_t len,
>  		     char *buf, loff_t *actread);
>  int ext4fs_find_file(const char *path, struct ext2fs_node *rootnode,
>  			struct ext2fs_node **foundnode, int expecttype);
> +int ext4fs_find_file1(const char *currpath, struct ext2fs_node *currroot,
> +		      struct ext2fs_node **currfound, int *foundtype);
>  int ext4fs_iterate_dir(struct ext2fs_node *dir, char *name,
>  			struct ext2fs_node **fnode, int *ftype);
>  
> diff --git a/fs/ext4/ext4fs.c b/fs/ext4/ext4fs.c
> index 3b12ec54fa2..b1359d14909 100644
> --- a/fs/ext4/ext4fs.c
> +++ b/fs/ext4/ext4fs.c
> @@ -208,11 +208,14 @@ int ext4fs_ls(const char *dirname)
>  
>  int ext4fs_exists(const char *filename)
>  {
> -	loff_t file_len;
> -	int ret;
> +	struct ext2fs_node *dirnode = NULL;
> +	int filetype;
>  
> -	ret = ext4fs_open(filename, &file_len);
> -	return ret == 0;
> +	if (!filename)
> +		return 0;
> +
> +	return ext4fs_find_file1(filename, &ext4fs_root->diropen, &dirnode,
> +				 &filetype);
>  }
>  
>  int ext4fs_size(const char *filename, loff_t *size)

-- 
// Caleb (they/them)