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Add support for #undef #137

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Merged
merged 2 commits into from
Jul 31, 2025
Merged

Add support for #undef #137

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145976e
Add support for `#undef`
Schamper Jul 31, 2025
c6b8ff4
Merge branch 'main' into undef
Schamper Jul 31, 2025
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13 changes: 13 additions & 0 deletions dissect/cstruct/parser.py
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@ def _tokencollection() -> TokenCollection:
TOK = TokenCollection()
TOK.add(r"#\[(?P<values>[^\]]+)\](?=\s*)", "CONFIG_FLAG")
TOK.add(r"#define\s+(?P<name>[^\s]+)(?P<value>[^\r\n]*)", "DEFINE")
TOK.add(r"#undef\s+(?P<name>[^\s]+)\s*", "UNDEF")
TOK.add(r"#ifdef\s+(?P<name>[^\s]+)\s*", "IFDEF")
TOK.add(r"#ifndef\s+(?P<name>[^\s]+)\s*", "IFNDEF")
TOK.add(r"#else\s*", "ELSE")
Expand Down Expand Up @@ -154,6 +155,16 @@ def _constant(self, tokens: TokenConsumer) -> None:

self.cstruct.consts[match["name"]] = value

def _undef(self, tokens: TokenConsumer) -> None:
const = tokens.consume()
pattern = self.TOK.patterns[self.TOK.UNDEF]
match = pattern.match(const.value).groupdict()

if match["name"] in self.cstruct.consts:
del self.cstruct.consts[match["name"]]
else:
raise ParserError(f"line {self._lineno(const)}: constant {match['name']!r} not defined")

def _enum(self, tokens: TokenConsumer) -> None:
# We cheat with enums because the entire enum is in the token
etok = tokens.consume()
Expand Down Expand Up @@ -443,6 +454,8 @@ def parse(self, data: str) -> None:
self._config_flag(tokens)
elif token == self.TOK.DEFINE:
self._constant(tokens)
elif token == self.TOK.UNDEF:
self._undef(tokens)
elif token == self.TOK.TYPEDEF:
self._typedef(tokens)
elif token == self.TOK.STRUCT:
Expand Down
13 changes: 13 additions & 0 deletions tests/test_parser.py
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Expand Up @@ -163,6 +163,19 @@ def test_typedef_pointer(cs: cstruct) -> None:
assert cs.PIMAGE_DATA_DIRECTORY.type == cs._IMAGE_DATA_DIRECTORY


def test_undef(cs: cstruct) -> None:
cdef = """
#define MY_CONST 42
#undef MY_CONST
"""
cs.load(cdef)

assert "MY_CONST" not in cs.consts

with pytest.raises(ParserError, match="line 1: constant 'MY_CONST' not defined"):
cs.load("#undef MY_CONST") # This should raise an error since MY_CONST is not defined


def test_conditional_ifdef(cs: cstruct) -> None:
cdef = """
#define MY_CONST 42
Expand Down