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fix: identify GPL-2.0, not LGPL-2.0, when the GPLv2 preamble names the LGPL #28

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Merged
nmatt0 merged 1 commit into from
Sep 18, 2026
Merged

fix: identify GPL-2.0, not LGPL-2.0, when the GPLv2 preamble names the LGPL #28

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10 changes: 8 additions & 2 deletions src/license.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -71,12 +71,18 @@ std::vector<std::string> identify_license_text(std::span<const uint8_t> data) {
};

// GNU family — disambiguate Affero/Lesser/Library and version by the dated
// title line. LGPL 2.0 (1991) is titled "Library General Public License";
// title line. LGPL 2.0 (1991) is titled "GNU LIBRARY GENERAL PUBLIC LICENSE";
// the 2.1 (1999) rename to "Lesser" is why v2 needs its own marker (without
// it an LGPL-2.0 COPYING is mis-identified as GPL-2.0).
//
// `library` matches only the all-caps *title*, never the mixed-case phrase
// "GNU Library General Public License": the latter appears in the GPLv2
// *preamble* ("...covered by the GNU Library General Public License
// instead.)"), so matching it flipped a genuine GPL-2.0 file to LGPL-2.0 and
// dropped GPL-2.0 entirely.
bool affero = has("GNU AFFERO GENERAL PUBLIC LICENSE") || has("GNU Affero");
bool lesser = has("GNU LESSER GENERAL PUBLIC LICENSE") || has("Lesser General Public");
bool library = has("GNU LIBRARY GENERAL PUBLIC LICENSE") || has("Library General Public License");
bool library = has("GNU LIBRARY GENERAL PUBLIC LICENSE");
if (has("Version 3, 29 June 2007")) {
if (affero) add("AGPL-3.0");
else if (lesser) add("LGPL-3.0");
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14 changes: 14 additions & 0 deletions tests/unit/unit_tests.cpp
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Expand Up @@ -1399,6 +1399,20 @@ static void test_license() {
// and plain GPL-2.0 is still GPL-2.0 (no false LGPL).
CHECK(lic_text("GNU GENERAL PUBLIC LICENSE\n Version 2, June 1991\n") ==
std::vector<std::string>{"GPL-2.0"});
// Regression: the real GPLv2 *preamble* names the LGPL ("...covered by the
// GNU Library General Public License instead."). That mixed-case mention must
// NOT flip a genuine GPL-2.0 file to LGPL-2.0, nor drop GPL-2.0. Only the
// all-caps LGPL *title* means LGPL-2.0.
auto gpl2_preamble = lic_text(
"GNU GENERAL PUBLIC LICENSE\n Version 2, June 1991\n\n"
" (Some other Free Software Foundation software is covered by the GNU\n"
"Library General Public License instead.) You can apply it too.\n");
CHECK(gpl2_preamble.size() == 1 && gpl2_preamble[0] == "GPL-2.0");
// and a real LGPL-2.0 (caps title) is still LGPL-2.0, even with a preamble.
auto lgpl2_full = lic_text(
"GNU LIBRARY GENERAL PUBLIC LICENSE\n Version 2, June 1991\n\n"
" This library is free software; you can redistribute it ...\n");
CHECK(lgpl2_full.size() == 1 && lgpl2_full[0] == "LGPL-2.0");

// New markers.
CHECK(lic_text("Boost Software License - Version 1.0") == std::vector<std::string>{"BSL-1.0"});
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