Fix Database::getHeaderInfo() signed-shift UB and use fixed-width Header types#558
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The big-endian assembly shifted unsigned char operands that promote to int, so bytes with the high bit set produced signed left-shift UB and sign-extended when widened to the Header fields. Cast each byte to uint32_t before shifting, via a local readBE32 helper that also removes the repetitive byte arithmetic. Header used platform-variable `unsigned long` (32-bit on LLP64 Windows, 64-bit on LP64), giving a cross-platform field-width mismatch. Switch the struct to fixed-width <cstdint> types (uint8_t / uint32_t). Fixes DB-02 and DB-03 from the code review.
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coverage: 99.688% (-0.02%) from 99.711% — fix-getheaderinfo-shift-ub into master |
SRombauts
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Summary
Fixes two findings from the deep code review (DB-02, DB-03) in
Database::getHeaderInfo()and the publicHeaderstruct.DB-02 — signed left-shift UB in the big-endian assembly
The multi-byte header fields were assembled from
unsigned charoperands, which promote tointbefore the<< 24shift. For any byte with the high bit set this is signed-left-shift undefined behaviour, and theintresult was then sign-extended when widened to the (LP64)unsigned longfields.Each byte is now cast to
std::uint32_tbefore shifting, through a small localreadBE32helper that also collapses the 14 repeated 4-line blocks.DB-03 — platform-variable field widths
Headerusedunsigned long, which is 32-bit on LLP64 (Windows) but 64-bit on LP64 (Linux/macOS), so the struct layout and field widths differed across platforms. The struct now uses fixed-width<cstdint>types (std::uint8_t/std::uint32_t).Test plan
SQLiteCpp_tests(MSVC, Debug) — clean.ctest -C Debug— 100% passed, includingDatabase.getHeaderInfo.No public API behaviour changes; the parsed values are identical, only the field types and the (previously UB) assembly path change.