Inside Bitcoin

1#!/usr/bin/env python3
2"""Check that a libsecp256k1 shared library exports only expected symbols.
3
4Usage examples:
5  - When building with Autotools:
6    ./tools/symbol-check.py .libs/libsecp256k1.so
7    ./tools/symbol-check.py .libs/libsecp256k1-<V>.dll
8    ./tools/symbol-check.py .libs/libsecp256k1.dylib
9
10  - When building with CMake:
11    ./tools/symbol-check.py build/lib/libsecp256k1.so
12    ./tools/symbol-check.py build/bin/libsecp256k1-<V>.dll
13    ./tools/symbol-check.py build/lib/libsecp256k1.dylib"""
14
15import re
16import sys
17import subprocess
18
19import lief
20
21
22class UnexpectedExport(RuntimeError):
23    pass
24
25
26def get_exported_exports(library) -> list[str]:
27    """Adapter function to get exported symbols based on the library format."""
28    if library.format == lief.Binary.FORMATS.ELF:
29        return [symbol.name for symbol in library.exported_symbols]
30    elif library.format == lief.Binary.FORMATS.PE:
31        return [entry.name for entry in library.get_export().entries]
32    elif library.format == lief.Binary.FORMATS.MACHO:
33        return [symbol.name[1:] for symbol in library.exported_symbols]
34    raise NotImplementedError(f"Unsupported format: {library.format}")
35
36
37def grep_expected_symbols() -> list[str]:
38    """Guess the list of expected exported symbols from the source code."""
39    grep_output = subprocess.check_output(
40        ["git", "grep", r"^\s*SECP256K1_API", "--", "include"],
41        universal_newlines=True,
42        encoding="utf-8"
43    )
44    lines = grep_output.split("\n")
45    pattern = re.compile(r'\bsecp256k1_\w+')
46    exported: list[str] = [pattern.findall(line)[-1] for line in lines if line.strip()]
47    return exported
48
49
50def check_symbols(library, expected_exports) -> None:
51    """Check that the library exports only the expected symbols."""
52    actual_exports = get_exported_exports(library)
53    unexpected_exports = set(actual_exports) - set(expected_exports)
54    if unexpected_exports != set():
55        raise UnexpectedExport(f"Unexpected exported symbols: {unexpected_exports}")
56
57def main():
58    if len(sys.argv) != 2:
59        print(__doc__)
60        return 1
61    library = lief.parse(sys.argv[1])
62    expected_exports = grep_expected_symbols()
63    try:
64        check_symbols(library, expected_exports)
65    except UnexpectedExport as e:
66        print(f"{sys.argv[0]}: In {sys.argv[1]}: {e}")
67        return 1
68    return 0
69
70
71if __name__ == "__main__":
72    sys.exit(main())
73