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    SubjectRe: Fw: [POSSIBLE-BUG] telldir() broken on ext3 dir_index'd directories just after the first entry.
    > [1.] One line summary of the problem:
    > telldir() broken on large ext3 dir_index'd directories because
    > getdents() gives d_off==0 for the first entry

    Here's a patch which fixes the problem, but note the following warning
    from the readdir man page:

    According to POSIX, the dirent structure contains a field char d_name[]
    of unspecified size, with at most NAME_MAX characters preceding the
    terminating null character. Use of other fields will harm the porta-
    bility of your programs.

    Also, as always, telldir() and seekdir() are truly awful interfaces
    because they implicitly assume that (a) a directory is a linear data
    structure, and (b) that the position in a directory can be expressed
    in a cookie which hsa only 31 bits on 32-bit systems.

    So there will be hash colliions that will cause programs that assume
    that seekdir(dirent->d_off) will always return the next directory
    entry to sometimes lose directory entries in the
    not-as-unlikely-as-we-would wish case of a 31-bit hash collision.
    Really, any program which is using telldir/seekdir really should be
    rewritten to not use these interfaces if at all possible. So with
    these caveats....

    - Ted

    Here is a patch which causes d_off of '.' to be 1, and for seekdir(1)
    to cause readdir to return the directory entry of '..'.

    Signed-off-by: "Theodore Ts'o" <>

    ===== fs/ext3/namei.c 1.59 vs edited =====
    --- 1.59/fs/ext3/namei.c 2004-10-19 05:40:30 -04:00
    +++ edited/fs/ext3/namei.c 2004-11-17 17:14:06 -05:00
    @@ -610,10 +610,15 @@ int ext3_htree_fill_tree(struct file *di
    de = (struct ext3_dir_entry_2 *) frames[0].bh->b_data;
    if ((err = ext3_htree_store_dirent(dir_file, 0, 0, de)) != 0)
    goto errout;
    + count++;
    + start_hash=2;
    + }
    + if (start_hash==2 && start_minor_hash==0) {
    + de = (struct ext3_dir_entry_2 *) frames[0].bh->b_data;
    de = ext3_next_entry(de);
    - if ((err = ext3_htree_store_dirent(dir_file, 0, 0, de)) != 0)
    + if ((err = ext3_htree_store_dirent(dir_file, 2, 0, de)) != 0)
    goto errout;
    - count += 2;
    + count++;

    while (1) {
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      Last update: 2005-03-22 14:08    [W:0.036 / U:43.824 seconds]
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