On Thu, Dec 22, 2022 at 10:03 PM Qu Wenruo <wqu@xxxxxxxx> wrote:
>
> Test case btrfs/154 is still using python2 script, which is already EOL.
> Some rolling distros like Archlinux is no longer providing python2
> package anymore.
>
> This means btrfs/154 will be harder and harder to run.
>
> To fix the problem, migreate the python script to python3, this involves
> the following changes:
>
> - Change common/config to use python3
> - Strong type conversion between string and bytes
> This means, anything involved in the forged bytes has to be bytes.
>
> And there is no safe way to convert forged bytes into string, unlike
> python2.
> I guess that's why the author went python2 in the first place.
>
> Thankfully os.rename() still accepts forged bytes.
>
> - Use bytes specific checks for invalid chars.
>
> The updated script can still cause the needed conflicts, can be verified
> through "btrfs ins dump-tree" command.
>
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
> ---
> common/config | 2 +-
> src/btrfs_crc32c_forged_name.py | 22 ++++++++++++++++------
> tests/btrfs/154 | 4 ++--
> 3 files changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/common/config b/common/config
> index b2802e5e..e2aba5a9 100644
> --- a/common/config
> +++ b/common/config
> @@ -212,7 +212,7 @@ export NFS4_SETFACL_PROG="$(type -P nfs4_setfacl)"
> export NFS4_GETFACL_PROG="$(type -P nfs4_getfacl)"
> export UBIUPDATEVOL_PROG="$(type -P ubiupdatevol)"
> export THIN_CHECK_PROG="$(type -P thin_check)"
> -export PYTHON2_PROG="$(type -P python2)"
> +export PYTHON3_PROG="$(type -P python3)"
> export SQLITE3_PROG="$(type -P sqlite3)"
> export TIMEOUT_PROG="$(type -P timeout)"
> export SETCAP_PROG="$(type -P setcap)"
> diff --git a/src/btrfs_crc32c_forged_name.py b/src/btrfs_crc32c_forged_name.py
> index 6c08fcb7..d29bbb70 100755
> --- a/src/btrfs_crc32c_forged_name.py
> +++ b/src/btrfs_crc32c_forged_name.py
> @@ -59,9 +59,10 @@ class CRC32(object):
> # deduce the 4 bytes we need to insert
> for c in struct.pack('<L',fwd_crc)[::-1]:
> bkd_crc = ((bkd_crc << 8) & 0xffffffff) ^ self.reverse[bkd_crc >> 24]
> - bkd_crc ^= ord(c)
> + bkd_crc ^= c
>
> - res = s[:pos] + struct.pack('<L', bkd_crc) + s[pos:]
> + res = bytes(s[:pos], 'ascii') + struct.pack('<L', bkd_crc) + \
> + bytes(s[pos:], 'ascii')
> return res
>
> def parse_args(self):
> @@ -72,6 +73,12 @@ class CRC32(object):
> help="number of forged names to create")
> return parser.parse_args()
>
> +def has_invalid_chars(result: bytes):
> + for i in result:
> + if i == 0 or i == int.from_bytes(b'/', byteorder="little"):
> + return True
> + return False
> +
> if __name__=='__main__':
>
> crc = CRC32()
> @@ -80,12 +87,15 @@ if __name__=='__main__':
> args = crc.parse_args()
> dirpath=args.dir
> while count < args.count :
> - origname = os.urandom (89).encode ("hex")[:-1].strip ("\x00")
> + origname = os.urandom (89).hex()[:-1].strip ("\x00")
> forgename = crc.forge(wanted_crc, origname, 4)
> - if ("/" not in forgename) and ("\x00" not in forgename):
> + if not has_invalid_chars(forgename):
> srcpath=dirpath + '/' + str(count)
> - dstpath=dirpath + '/' + forgename
> - file (srcpath, 'a').close()
> + # We have to convert all strings to bytes to concatenate the forged
> + # name (bytes).
> + # Thankfully os.rename() can accept bytes directly.
> + dstpath=bytes(dirpath, "ascii") + bytes('/', "ascii") + forgename
> + open(srcpath, mode="a").close()
> os.rename(srcpath, dstpath)
> os.system('btrfs fi sync %s' % (dirpath))
> count+=1;
> diff --git a/tests/btrfs/154 b/tests/btrfs/154
> index 240c504c..6be2d5f6 100755
> --- a/tests/btrfs/154
> +++ b/tests/btrfs/154
> @@ -21,7 +21,7 @@ _begin_fstest auto quick
>
> _supported_fs btrfs
> _require_scratch
> -_require_command $PYTHON2_PROG python2
> +_require_command $PYTHON3_PROG python3
>
> # Currently in btrfs the node/leaf size can not be smaller than the page
> # size (but it can be greater than the page size). So use the largest
> @@ -42,7 +42,7 @@ _scratch_mount
> # ...
> #
>
> -$PYTHON2_PROG $here/src/btrfs_crc32c_forged_name.py -d $SCRATCH_MNT -c 310
> +$PYTHON3_PROG $here/src/btrfs_crc32c_forged_name.py -d $SCRATCH_MNT -c 310
> echo "Silence is golden"
>
> # success, all done
> --
> 2.39.0
>
This test makes my eyes bleed, but that's not a reason to say no to
this patch...
Reviewed-by: Neal Gompa <neal@xxxxxxxxx>
--
真実はいつも一つ！/ Always, there's only one truth!
