Re: [PATCH] AOSP: erofs-utils: fix sub directory prefix path in canned fs_config

[Gao Xiang <hsiangkao@redhat.com>]

On Tue, Dec 22, 2020 at 04:10:58PM +0800, Yue Hu wrote:
> On Tue, 22 Dec 2020 15:04:58 +0800
> Gao Xiang <hsiangkao@redhat.com> wrote:
> 
> > Hi Yue,
> > 
> > On Tue, Dec 22, 2020 at 02:31:12PM +0800, Gao Xiang wrote:
> > 
> > ...
> > 
> > > 
> > > Ok, I will try to find some clue to verify later.
> > >   
> > > >   
> > > > >   
> > > > > > Moreover, we should not add the mount point to fspath on root inode for
> > > > > > fs_config() branch.    
> > > > > 
> > > > > Is there some descriptive words or reference for this? To be honest,
> > > > > I'm quite unsure about this kind of Android-specific things... :(  
> > > > 
> > > > Refer to change: mksquashfs: Run android_fs_config() on the root inode
> > > > 
> > > > I think erofs of AOSP has this issue also. Am i right?  
> > > 
> > > Not quite sure if it effects non-canned fs_config after
> > > reading the commit message...
> > > https://android.googlesource.com/platform/external/squashfs-tools/+/85a6bc1e52bb911f195c5dc0890717913938c2d1%5E%21/#F0
> > > 
> > > And no permission to access Bug 72745016, so...
> > > maybe we need to limit this to non-canned fs_config only?
> > > (at least confirming the original case would be better)
> > > 
> > > BTW, Also, from its testcase command line in the commit message:
> > > "mksquashfs path system.raw.img -fs-config-file fs_config -android-fs-config"
> > > 
> > > I'm not sure if "--mount-point" is passed in so I think for
> > > such case no need to use such "goto" as well? 
> > > 
> > > Thanks,
> > > Gao Xiang  
> > 
> > Could you verify the following patch if possible? (without compilation,
> > I don't have test environment now since AOSP code is on my PC)
> > 
> > From: Yue Hu <huyue2@yulong.com>
> > Date: Tue, 22 Dec 2020 14:52:22 +0800
> > Subject: [PATCH] AOSP: erofs-utils: fix sub-directory prefix for canned
> >  fs_config
> > 
> > "failed to find [%s] in canned fs_config" is observed by using
> > "--fs-config-file" option under Android 10.
> > 
> > Notice that canned fs_config has a prefix to sub-directory if
> > "--mount-point" presents. However, such prefix cannot be added by
> > just using erofs_fspath().
> > 
> > Fixes: 8a9e8046f170 ("AOSP: erofs-utils: add fs_config support")
> > Signed-off-by: Yue Hu <huyue2@yulong.com>
> > Signed-off-by: Gao Xiang <hsiangkao@aol.com>
> > ---
> >  lib/inode.c | 18 +++++++++++-------
> >  1 file changed, 11 insertions(+), 7 deletions(-)
> > 
> > diff --git a/lib/inode.c b/lib/inode.c
> > index 3d634fc..9469074 100644
> > --- a/lib/inode.c
> > +++ b/lib/inode.c
> > @@ -701,21 +701,25 @@ int erofs_droid_inode_fsconfig(struct erofs_inode *inode,
> >  	char *fspath;
> >  
> >  	inode->capabilities = 0;
> > +	if (!cfg.mount_point)
> > +		fspath = erofs_fspath(path);
> 
> lib/inode.c:688:10: error: assigning to 'char *' from 'const char *' discards...
>                 fspath = erofs_fspath(path);
>                        ^ ~~~~~~~~~~~~~~~~~~
> 
> -           fspath = erofs_fspath(path);
> +         fspath = (char *)erofs_fspath(path);

oops, I think it can be modified as a temporary workaround, will submit a formal
patch after verification.

> 
> 
> > +	else if (asprintf(&fspath, "%s/%s", cfg.mount_point,
> > +			  erofs_fspath(path)) <= 0)
> 
> The argument of path will be root directory. And canned fs_config for root directory as
> below:
> 
> 0 0 755 selabel=u:object_r:rootfs:s0 capabilities=0x0
> 
> So, cannot add mount point to root directory for canned fs_config. And what about non-canned
> fs_config?

Not quite sure what you mean. For non-canned fs_config, we didn't observed any strange
before (I ported to cuttlefish and hikey960 with boot success, also as I mentioned before
some other vendors already use it.)

I think the following commit is only useful for squashfs since its (non)root inode
workflows are different, so need to add in two difference place. But mkfs.erofs is not.
https://android.googlesource.com/platform/external/squashfs-tools/+/85a6bc1e52bb911f195c5dc0890717913938c2d1%5E%21/#F0

For root inode is erofs, I think erofs_fspath(path) would return "", so that case
is included as well.... Am I missing something?

Thanks,
Gao Xiang

> 
> Thx.
> 
> 
> > +		return -ENOMEM;
> > +
> > +
> >  	if (cfg.fs_config_file)
> > -		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);
> > +
> > +	if (cfg.mount_point)
> >  		free(fspath);
> > -	}
> >  	st->st_uid = uid;
> >  	st->st_gid = gid;
> >  	st->st_mode = mode | stat_file_type_mask;
>