def whichdb(filename):
"""Guess which db package to use to open a db file.
Return values:
- None if the database file can't be read;
- empty string if the file can be read but can't be recognized
- the name of the dbm submodule (e.g. 'ndbm' or 'gnu') if recognized.
Importing the given module may still fail, and opening the
database using that module may still fail.
- Actually it is a bit extended form of `whichdb.whichdb`
that accounts for `sqlite3`
"""
tst = _whichdb(filename)
if tst or tst is None: return tst
if issqlite3(filename): return "sqlite3"
return tst
def whichdb(filename):
"""Guess which db package to use to open a db file.
Return values:
- None if the database file can't be read;
- empty string if the file can be read but can't be recognized
- the name of the dbm submodule (e.g. 'ndbm' or 'gnu') if recognized.
Importing the given module may still fail, and opening the
database using that module may still fail.
- Actually it is a bit extended form of `dbm.whichdb`
that accounts for `bsddb3` and `sqlite3`
"""
## use the standard function
tst = dbm.whichdb(filename)
## identified or non-existing DB ?
if tst or tst is None: return tst
## non-identified DB
## check for bsddb magic numbers (from python2)
try:
with io.open(filename, 'rb') as f:
# Read the start of the file -- the magic number
s16 = f.read(16)
except OSError:
return None
s = s16[0:4]
# Return "" if not at least 4 bytes
if len(s) != 4:
return ""
# Convert to 4-byte int in native byte order -- return "" if impossible
try:
(magic, ) = struct.unpack("=l", s)
except struct.error:
return ""
# Check for GNU dbm
if magic in (0x13579ace, 0x13579acd, 0x13579acf):
return "dbm.gnu"
# Check for old Berkeley db hash file format v2
if magic in (0x00061561, 0x61150600):
return "bsddb185"
# Later versions of Berkeley db hash file have a 12-byte pad in
# front of the file type
try:
(magic, ) = struct.unpack("=l", s16[-4:])
except struct.error:
return ""
# Check for BSD hash
if magic in (0x00061561, 0x61150600):
return "bsddb3"
if issqlite3(filename): return 'sqlite3'
# Unknown
return ""