File that doesn't exist being returned by ReadDir()

[racingmars]

On my ext4 filesystem, the ReadDir() function is returning an additional file that doesn't exist anymore. If I list from the operating system, I see:

% ls -al /usr/lib/python3.8 
total 280
drwxr-xr-x   3 root root  12288 Dec 12  2020 ./
drwxr-xr-x 260 root root 258048 Sep  4 17:00 ../
drwxr-xr-x   3 root root  12288 May  6  2023 site-packages/

However, if I call ReadDir("/usr/lib/python3.8") on my open filesystem, I get back two entries in the array:

site-packages
LICENSE.txt

But LICENSE.txt does not exist anymore.

Tracing through the code in the debugger, I can see that the DirectoryEntry2 structure data for this "bad" file is:

{
    Inode: 0,
    RecLen: 4048,
    NameLen: 11,
    Flags: 1,
    Name: "LICENSE.txt",
}

From the ext4 documentation at https://www.kernel.org/doc/html/latest/filesystems/ext4/dynamic.html#linear-classic-directories, it says that a directory entry with inode set to 0 is an unused entry, and that "the last entry in the block has a record length that takes it all the way to the end of the block". This entry appears to be both the "unused inode" and "end-of-block" directory entry, and it is just a fluke that there is old data (the filename/namelen>0) also in the entry.

The fix appears to be to add a new check around line 220 of fs.go in extractDirectoryEntries():

if dirEntry.Inode == 0 {
    // unused directory entry
    continue
}

So that the data in this unused entry doesn't get appended to the dirEntries slice.

[masahiro331]

Thank you for issues.
Could you fix this issue?