GNU gettext is a popular solution in free/open source software world to do i18n/l10n of software, by providing translated strings that will substitute strings in original language (typically, English).
gettext .mo is a binary database format which stores these string translation pairs in an efficient binary format, ready to be used by gettext-enabled software. .mo format is a result of compilation of text-based .po files using msgfmt utility. The reverse conversion (.mo -> .po) is also possible using msgunfmt decompiler utility.
This page hosts a formal specification of gettext binary database using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for Python generated by Kaitai Struct depends on the Python runtime library. You have to install it before you can parse data.
The Python runtime library can be installed from PyPI:
python3 -m pip install kaitaistructParse a local file and get structure in memory:
data = GettextMo.from_file("path/to/local/file.mo")
Or parse structure from a bytes:
from kaitaistruct import KaitaiStream, BytesIO
raw = b"\x00\x01\x02..."
data = GettextMo(KaitaiStream(BytesIO(raw)))
After that, one can get various attributes from the structure by invoking getter methods like:
data.signature # => get signature
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO
if getattr(kaitaistruct, 'API_VERSION', (0, 9)) < (0, 9):
raise Exception("Incompatible Kaitai Struct Python API: 0.9 or later is required, but you have %s" % (kaitaistruct.__version__))
class GettextMo(KaitaiStruct):
"""[GNU gettext](https://www.gnu.org/software/gettext/) is a popular
solution in free/open source software world to do i18n/l10n of
software, by providing translated strings that will substitute
strings in original language (typically, English).
gettext .mo is a binary database format which stores these string
translation pairs in an efficient binary format, ready to be used by
gettext-enabled software. .mo format is a result of compilation of
text-based .po files using
[msgfmt](https://www.gnu.org/software/gettext/manual/html_node/msgfmt-Invocation.html#msgfmt-Invocation)
utility. The reverse conversion (.mo -> .po) is also possible using
[msgunfmt](https://www.gnu.org/software/gettext/manual/html_node/msgunfmt-Invocation.html#msgunfmt-Invocation)
decompiler utility.
.. seealso::
Source - https://gitlab.com/worr/libintl
"""
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.signature = self._io.read_bytes(4)
self.mo = GettextMo.Mo(self._io, self, self._root)
class HashLookupIteration(KaitaiStruct):
def __init__(self, idx, collision_step, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self.idx = idx
self.collision_step = collision_step
self._read()
def _read(self):
pass
@property
def original(self):
if hasattr(self, '_m_original'):
return self._m_original
self._m_original = self._root.mo.originals[self.idx].str
return getattr(self, '_m_original', None)
@property
def translation(self):
if hasattr(self, '_m_translation'):
return self._m_translation
self._m_translation = self._root.mo.translations[self.idx].str
return getattr(self, '_m_translation', None)
@property
def next_idx(self):
if hasattr(self, '_m_next_idx'):
return self._m_next_idx
self._m_next_idx = ((self.idx + self.collision_step) - (self._root.mo.num_hashtable_items if self.idx >= (self._root.mo.num_hashtable_items - self.collision_step) else 0))
return getattr(self, '_m_next_idx', None)
@property
def next(self):
if hasattr(self, '_m_next'):
return self._m_next
_pos = self._io.pos()
self._io.seek(0)
self._m_next = GettextMo.HashLookupIteration(self._root.mo.hashtable_items[self.next_idx].val, self.collision_step, self._io, self, self._root)
self._io.seek(_pos)
return getattr(self, '_m_next', None)
class LookupIteration(KaitaiStruct):
def __init__(self, current, query, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self.current = current
self.query = query
self._read()
def _read(self):
pass
@property
def found(self):
if hasattr(self, '_m_found'):
return self._m_found
self._m_found = self.query == self.current.original
return getattr(self, '_m_found', None)
@property
def next(self):
if hasattr(self, '_m_next'):
return self._m_next
if not (self.found):
_pos = self._io.pos()
self._io.seek(0)
self._m_next = GettextMo.LookupIteration(self.current.next, self.query, self._io, self, self._root)
self._io.seek(_pos)
return getattr(self, '_m_next', None)
class HashtableLookup(KaitaiStruct):
"""def lookup(s:str, t:gettext_mo.GettextMo):
try:
l=gettext_mo.GettextMo.HashtableLookup(s, string_hash(s), t._io, _parent=t, _root=t)
e=l.entry
while(not e.found):
e=e.next
return e.current
except:
raise Exception("Not found "+s+" in the hashtable!")
lookup(t.mo.originals[145].str, t)
.. seealso::
Source - https://gitlab.com/worr/libintl/raw/master/src/lib/libintl/gettext.c
"""
def __init__(self, query, hash, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self.query = query
self.hash = hash
self._read()
def _read(self):
pass
@property
def collision_step(self):
if hasattr(self, '_m_collision_step'):
return self._m_collision_step
self._m_collision_step = ((self.hash % (self._root.mo.num_hashtable_items - 2)) + 1)
return getattr(self, '_m_collision_step', None)
@property
def idx(self):
if hasattr(self, '_m_idx'):
return self._m_idx
self._m_idx = (self.hash % self._root.mo.num_hashtable_items)
return getattr(self, '_m_idx', None)
@property
def hash_lookup_iteration(self):
if hasattr(self, '_m_hash_lookup_iteration'):
return self._m_hash_lookup_iteration
_pos = self._io.pos()
self._io.seek(0)
self._m_hash_lookup_iteration = GettextMo.HashLookupIteration(self._root.mo.hashtable_items[self.idx].val, self.collision_step, self._io, self, self._root)
self._io.seek(_pos)
return getattr(self, '_m_hash_lookup_iteration', None)
@property
def entry(self):
if hasattr(self, '_m_entry'):
return self._m_entry
_pos = self._io.pos()
self._io.seek(0)
self._m_entry = GettextMo.LookupIteration(self.hash_lookup_iteration, self.query, self._io, self, self._root)
self._io.seek(_pos)
return getattr(self, '_m_entry', None)
class Mo(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
_on = self._root.signature
if _on == b"\xDE\x12\x04\x95":
self._is_le = True
elif _on == b"\x95\x04\x12\xDE":
self._is_le = False
if not hasattr(self, '_is_le'):
raise kaitaistruct.UndecidedEndiannessError("/types/mo")
elif self._is_le == True:
self._read_le()
elif self._is_le == False:
self._read_be()
def _read_le(self):
self.version = GettextMo.Mo.Version(self._io, self, self._root, self._is_le)
self.num_translations = self._io.read_u4le()
self.ofs_originals = self._io.read_u4le()
self.ofs_translations = self._io.read_u4le()
self.num_hashtable_items = self._io.read_u4le()
self.ofs_hashtable_items = self._io.read_u4le()
def _read_be(self):
self.version = GettextMo.Mo.Version(self._io, self, self._root, self._is_le)
self.num_translations = self._io.read_u4be()
self.ofs_originals = self._io.read_u4be()
self.ofs_translations = self._io.read_u4be()
self.num_hashtable_items = self._io.read_u4be()
self.ofs_hashtable_items = self._io.read_u4be()
class Version(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None, _is_le=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._is_le = _is_le
self._read()
def _read(self):
if not hasattr(self, '_is_le'):
raise kaitaistruct.UndecidedEndiannessError("/types/mo/types/version")
elif self._is_le == True:
self._read_le()
elif self._is_le == False:
self._read_be()
def _read_le(self):
self.version_raw = self._io.read_u4le()
def _read_be(self):
self.version_raw = self._io.read_u4be()
@property
def major(self):
if hasattr(self, '_m_major'):
return self._m_major
self._m_major = (self.version_raw >> 16)
return getattr(self, '_m_major', None)
@property
def minor(self):
if hasattr(self, '_m_minor'):
return self._m_minor
self._m_minor = (self.version_raw & 65535)
return getattr(self, '_m_minor', None)
class HashtableItem(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None, _is_le=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._is_le = _is_le
self._read()
def _read(self):
if not hasattr(self, '_is_le'):
raise kaitaistruct.UndecidedEndiannessError("/types/mo/types/hashtable_item")
elif self._is_le == True:
self._read_le()
elif self._is_le == False:
self._read_be()
def _read_le(self):
self.raw_val = self._io.read_u4le()
def _read_be(self):
self.raw_val = self._io.read_u4be()
@property
def mask(self):
if hasattr(self, '_m_mask'):
return self._m_mask
self._m_mask = 2147483648
return getattr(self, '_m_mask', None)
@property
def val_1(self):
if hasattr(self, '_m_val_1'):
return self._m_val_1
if self.raw_val != 0:
self._m_val_1 = (self.raw_val - 1)
return getattr(self, '_m_val_1', None)
@property
def is_system_dependent(self):
if hasattr(self, '_m_is_system_dependent'):
return self._m_is_system_dependent
if self.raw_val != 0:
self._m_is_system_dependent = (self.val_1 & self.mask) == 1
return getattr(self, '_m_is_system_dependent', None)
@property
def val(self):
if hasattr(self, '_m_val'):
return self._m_val
if self.raw_val != 0:
self._m_val = (self.val_1 & ~(self.mask))
return getattr(self, '_m_val', None)
class Descriptor(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None, _is_le=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._is_le = _is_le
self._read()
def _read(self):
if not hasattr(self, '_is_le'):
raise kaitaistruct.UndecidedEndiannessError("/types/mo/types/descriptor")
elif self._is_le == True:
self._read_le()
elif self._is_le == False:
self._read_be()
def _read_le(self):
self.len_str = self._io.read_u4le()
self.ofs_str = self._io.read_u4le()
def _read_be(self):
self.len_str = self._io.read_u4be()
self.ofs_str = self._io.read_u4be()
@property
def str(self):
if hasattr(self, '_m_str'):
return self._m_str
io = self._root._io
_pos = io.pos()
io.seek(self.ofs_str)
if self._is_le:
self._m_str = (KaitaiStream.bytes_terminate(io.read_bytes(self.len_str), 0, False)).decode(u"UTF-8")
else:
self._m_str = (KaitaiStream.bytes_terminate(io.read_bytes(self.len_str), 0, False)).decode(u"UTF-8")
io.seek(_pos)
return getattr(self, '_m_str', None)
@property
def originals(self):
if hasattr(self, '_m_originals'):
return self._m_originals
io = self._root._io
_pos = io.pos()
io.seek(self.ofs_originals)
if self._is_le:
self._m_originals = []
for i in range(self.num_translations):
self._m_originals.append(GettextMo.Mo.Descriptor(io, self, self._root, self._is_le))
else:
self._m_originals = []
for i in range(self.num_translations):
self._m_originals.append(GettextMo.Mo.Descriptor(io, self, self._root, self._is_le))
io.seek(_pos)
return getattr(self, '_m_originals', None)
@property
def translations(self):
if hasattr(self, '_m_translations'):
return self._m_translations
io = self._root._io
_pos = io.pos()
io.seek(self.ofs_translations)
if self._is_le:
self._m_translations = []
for i in range(self.num_translations):
self._m_translations.append(GettextMo.Mo.Descriptor(io, self, self._root, self._is_le))
else:
self._m_translations = []
for i in range(self.num_translations):
self._m_translations.append(GettextMo.Mo.Descriptor(io, self, self._root, self._is_le))
io.seek(_pos)
return getattr(self, '_m_translations', None)
@property
def hashtable_items(self):
if hasattr(self, '_m_hashtable_items'):
return self._m_hashtable_items
if self.ofs_hashtable_items != 0:
io = self._root._io
_pos = io.pos()
io.seek(self.ofs_hashtable_items)
if self._is_le:
self._m_hashtable_items = []
for i in range(self.num_hashtable_items):
self._m_hashtable_items.append(GettextMo.Mo.HashtableItem(io, self, self._root, self._is_le))
else:
self._m_hashtable_items = []
for i in range(self.num_hashtable_items):
self._m_hashtable_items.append(GettextMo.Mo.HashtableItem(io, self, self._root, self._is_le))
io.seek(_pos)
return getattr(self, '_m_hashtable_items', None)