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Raise a clear error on incomplete Type1 font sections #32193

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Raise a clear error on incomplete Type1 font sections #32193

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114c86e
Raise a clear error on incomplete Type1 font sections
vsaraikin Aug 9, 2026
2abb93a
Catch the incomplete section at the call site instead
vsaraikin Aug 11, 2026
fea4afd
Split the parser lookup out of the try block
vsaraikin Aug 12, 2026
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59 changes: 30 additions & 29 deletions lib/matplotlib/_type1font.py
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Original file line number Diff line number Diff line change
Expand Up @@ -523,12 +523,18 @@ def _parse(self):

# Some values need special parsing
if key in ('Subrs', 'CharStrings', 'Encoding', 'OtherSubrs'):
prop[key], endpos = {
parser = {
'Subrs': self._parse_subrs,
'CharStrings': self._parse_charstrings,
'Encoding': self._parse_encoding,
'OtherSubrs': self._parse_othersubrs
}[key](source, data)
}[key]
try:
prop[key], endpos = parser(source, data)
except StopIteration:
raise RuntimeError(
f"Malformed Type1 font file: Incomplete /{key}"
) from None
pos.setdefault(key, []).append((keypos, endpos))
continue

Expand Down Expand Up @@ -618,33 +624,28 @@ def _parse_subrs(self, tokens, _data):
# front lets a malformed font declare a huge count in a few bytes and
# force a large allocation before it is rejected.
entries = {}
try:
for _ in range(count):
next(t for t in tokens if t.is_keyword('dup'))
index_token = next(tokens)
if not index_token.is_number():
raise RuntimeError(
"Token following dup in Subrs definition must be a "
f"number, was {index_token}"
)
nbytes_token = next(tokens)
if not nbytes_token.is_number():
raise RuntimeError(
"Second token following dup in Subrs definition must "
f"be a number, was {nbytes_token}"
)
token = next(tokens)
if not token.is_keyword(self._abbr['RD']):
raise RuntimeError(
f"Token preceding subr must be {self._abbr['RD']}, "
f"was {token}"
)
binary_token = tokens.send(1+nbytes_token.value())
entries[index_token.value()] = binary_token.value()
except StopIteration:
raise RuntimeError(
"Malformed Type1 font file: Incomplete /Subrs"
) from None
for _ in range(count):
next(t for t in tokens if t.is_keyword('dup'))
index_token = next(tokens)
if not index_token.is_number():
raise RuntimeError(
"Token following dup in Subrs definition must be a "
f"number, was {index_token}"
)
nbytes_token = next(tokens)
if not nbytes_token.is_number():
raise RuntimeError(
"Second token following dup in Subrs definition must "
f"be a number, was {nbytes_token}"
)
token = next(tokens)
if not token.is_keyword(self._abbr['RD']):
raise RuntimeError(
f"Token preceding subr must be {self._abbr['RD']}, "
f"was {token}"
)
binary_token = tokens.send(1+nbytes_token.value())
entries[index_token.value()] = binary_token.value()

# The indices must cover 0 to count-1 exactly.
if (len(entries) != count
Expand Down
16 changes: 16 additions & 0 deletions lib/matplotlib/tests/test_type1font.py
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Original file line number Diff line number Diff line change
Expand Up @@ -210,3 +210,19 @@ def test_Subrs_bad_indices(tmp_path, indices):
# past the end nor a duplicate may reach the returned array.
with pytest.raises(RuntimeError, match='indices do not cover'):
t1f.Type1Font(_write_subrs_pfa(tmp_path / 'x.pfa', indices))


@pytest.mark.parametrize('private, section', [
(b'/CharStrings 1 begin\n/.notdef 5 RD \x00\x01\x02\x03\x04 ND\n',
'CharStrings'),
(b'/CharStrings 1\n', 'CharStrings'),
(b'/CharStrings 1 begin\n', 'CharStrings'),
(b'/Encoding 1 array\ndup 0 /.notdef put\n', 'Encoding'),
(b'/OtherSubrs [ {} {} \n', 'OtherSubrs'),
])
def test_incomplete_sections(tmp_path, private, section):
# A font that ends in the middle of a section used to raise a bare
# StopIteration out of the parser, which says nothing about the file.
path = _write_pfa(tmp_path / 'x.pfa', private)
with pytest.raises(RuntimeError, match=f'Incomplete /{section}'):
t1f.Type1Font(path)
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