On 2022/12/25 20:50, Zorro Lang wrote:
On Sun, Dec 25, 2022 at 08:11:02PM +0800, Qu Wenruo wrote:
On 2022/12/25 19:51, Zorro Lang wrote:
On Fri, Dec 23, 2022 at 10:56:42AM +0800, Qu Wenruo 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)"
How about:
export PYTHON_PROG="$(type -P python)"
export PYTHON2_PROG="$(type -P python2)"
export PYTHON3_PROG="$(type -P python3)"
maybe someone still need python2, or maybe someone doesn't care the version.
Even for distros which completely get rid of python2 and make python3
default, there is still python3.
And python is just a softlink to python3, which further links to the real
python
$ type -P python2
$ type -P python3
/usr/bin/python3
$ type -P python
/usr/bin/python
$ ls -alh /usr/bin/python
lrwxrwxrwx 1 root root 7 Nov 1 22:18 /usr/bin/python -> python3
$ ls -alh /usr/bin/python3
lrwxrwxrwx 1 root root 10 Nov 1 22:18 /usr/bin/python3 -> python3.10
Secondly, for this particular case, we must distinguish python2 and python3,
especially due to the strong requirement for string encoding.
So to your PYTHON_PROG usage, no, it's not good at all, it's going to be
distro dependent and will be a disaster if some one is using PYTHON_PROG.
For PYTHON2_PROG, there is no usage of it any more, thus I see now reason to
define it.
OK, due to only btrfs/154 uses this PYTHON?_PROG thing now, we can talk about
that later. This patch looks good to me.
In fact, I'd prefer to use C to do the CRC32C hash conflicts, especially
considering how hard it is already in python3 to parse any invalid bytes.
(And some other weird behaviors, like using hard coded filename name
lengh 89, which later converts to hex string and has to get rid of
invalid chars like \0 and \/)
But that would be another (small) project to go.
Until then, let's keep the single (and bad example) python3.
Thanks,
Qu
Reviewed-by: Zorro Lang <zlang@xxxxxxxxxx>
Thanks,
Qu
Thanks,
Zorro
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
