linux-ext4 - Re: [PATCH 02/25] e2fsprogs: Remove impossible name

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Message-Id: <EF91DE91-F63F-423E-BEE3-1F3B8D3B8B4B@dilger.ca>
Date:	Fri, 16 Sep 2011 16:30:20 -0600
From:	Andreas Dilger <adilger@...ger.ca>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 02/25] e2fsprogs: Remove impossible name_len tests.

On 2011-09-16, at 2:49 PM, Eric Sandeen wrote:
> The name_len field in ext2_dir_entry is actually comprised of
> the name length in the lower 8 bytes, and the filetype in the
> high 8 bytes.  So in places, we mask name_len with 0xFF to
> get the actual length.
> 
> But once we have masked name_len with 0xFF, there is no point
> in testing whether it is greater than EXT2_NAME_LEN, which
> is 255 - or 0xFF.  So all of these tests are extraneous.

This makes me want to remove uses of ext2_dir_entry and instead use
ext2_dir_entry_2 everywhere.  That will avoid a lot of potential
errors in the code, and I think the only possible use for the old
ext2_dir_entry is for ancient big-endian filesystems that were "v1"
format and didn't have EXT2_INCOMPAT_FILETYPE (which appeared in
e2fsprogs commit 89fe431a8 from Linux 2.1.90).

> Signed-off-by: Eric Sandeen <sandeen@...hat.com>
> ---
> debugfs/dump.c   |    3 +--
> debugfs/htree.c  |    3 +--
> debugfs/ls.c     |    3 +--
> e2fsck/message.c |    2 --
> e2fsck/pass2.c   |    6 ------
> 5 files changed, 3 insertions(+), 14 deletions(-)
> 
> diff --git a/debugfs/dump.c b/debugfs/dump.c
> index 4cf0752..ec36eca 100644
> --- a/debugfs/dump.c
> +++ b/debugfs/dump.c
> @@ -300,8 +300,7 @@ static int rdump_dirent(struct ext2_dir_entry *dirent,
> 	const char *dumproot = private;
> 	struct ext2_inode inode;
> 
> -	thislen = ((dirent->name_len & 0xFF) < EXT2_NAME_LEN
> -		   ? (dirent->name_len & 0xFF) : EXT2_NAME_LEN);
> +	thislen = dirent->name_len & 0xFF;
> 	strncpy(name, dirent->name, thislen);
> 	name[thislen] = 0;
> 
> diff --git a/debugfs/htree.c b/debugfs/htree.c
> index b829e25..de36bd4 100644
> --- a/debugfs/htree.c
> +++ b/debugfs/htree.c
> @@ -81,8 +81,7 @@ static void htree_dump_leaf_node(ext2_filsys fs, ext2_ino_t ino,
> 				blk);
> 			break;
> 		}
> -		thislen = ((dirent->name_len & 0xFF) < EXT2_NAME_LEN) ?
> -			(dirent->name_len & 0xFF) : EXT2_NAME_LEN;
> +		thislen = dirent->name_len & 0xFF;
> 		strncpy(name, dirent->name, thislen);
> 		name[thislen] = '\0';
> 		errcode = ext2fs_dirhash(hash_alg, name,
> diff --git a/debugfs/ls.c b/debugfs/ls.c
> index 8e019d2..e01fd20 100644
> --- a/debugfs/ls.c
> +++ b/debugfs/ls.c
> @@ -60,8 +60,7 @@ static int list_dir_proc(ext2_ino_t dir EXT2FS_ATTR((unused)),
> 	int			thislen;
> 	struct list_dir_struct *ls = (struct list_dir_struct *) private;
> 
> -	thislen = ((dirent->name_len & 0xFF) < EXT2_NAME_LEN) ?
> -		(dirent->name_len & 0xFF) : EXT2_NAME_LEN;
> +	thislen = dirent->name_len & 0xFF;
> 	strncpy(name, dirent->name, thislen);
> 	name[thislen] = '\0';
> 	ino = dirent->inode;
> diff --git a/e2fsck/message.c b/e2fsck/message.c
> index 49b861d..565c3cd 100644
> --- a/e2fsck/message.c
> +++ b/e2fsck/message.c
> @@ -372,8 +372,6 @@ static _INLINE_ void expand_dirent_expression(ext2_filsys fs, char ch,
> 		break;
> 	case 'n':
> 		len = dirent->name_len & 0xFF;
> -		if (len > EXT2_NAME_LEN)
> -			len = EXT2_NAME_LEN;
> 		if ((ext2fs_get_rec_len(fs, dirent, &rec_len) == 0) &&
> 		    (len > rec_len))
> 			len = rec_len;
> diff --git a/e2fsck/pass2.c b/e2fsck/pass2.c
> index e57afb9..9c44aa2 100644
> --- a/e2fsck/pass2.c
> +++ b/e2fsck/pass2.c
> @@ -858,12 +858,6 @@ out_htree:
> 			} else
> 				goto abort_free_dict;
> 		}
> -		if ((dirent->name_len & 0xFF) > EXT2_NAME_LEN) {
> -			if (fix_problem(ctx, PR_2_FILENAME_LONG, &cd->pctx)) {
> -				dirent->name_len = EXT2_NAME_LEN;
> -				dir_modified++;
> -			}
> -		}
> 
> 		if (dot_state == 0) {
> 			if (check_dot(ctx, dirent, ino, &cd->pctx))
> -- 
> 1.7.4.1
> 
> --
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Cheers, Andreas





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