MDEV-39744: Assertion buf != end failed in decimal_mul#5265
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raghunandanbhat wants to merge 1 commit into
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MDEV-39744: Assertion buf != end failed in decimal_mul#5265raghunandanbhat wants to merge 1 commit into
buf != end failed in decimal_mul#5265raghunandanbhat wants to merge 1 commit into
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This pull request fixes an assertion failure buf != end in decimal_mul by replacing the assertion and loop with a safe boundary check (buf < end). It also adds test cases to verify the fix. The reviewer suggests removing a redundant and fragile fuzzer-generated query containing LOCALTIME from the test suite, as the other deterministic queries are sufficient to cover the bug.
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Problem: With `div_precision_increment=0`, a division whose quotient rounds away to zero (e.g. -299/450) produced a decimal with no digit words (intg=0 and frac=0) while still keeping the sign bit set. That is a malformed value. Multiplying such a malformed zero value by another zero reached the negative-zero check in `decimal_mul`, where there were no digit words to scan, leading to assertion failure. Fix: Fix `do_div_mod`, which produced the malformed zero. `do_div_mod` already normalizes this case to a canonical zero on the modulo path; do the same on the division path: when the quotient has no digits (intg0 = 0 && frac0 = 0) return a correct decimal zero instead of a digit-less, signed value.
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fixes MDEV-39744
Problem:
With
div_precision_increment=0, a division whose quotient rounds away to zero (e.g. -299/450) produced a decimal with no digit words (intg=0 and frac=0) while still keeping the sign bit set. That is a malformed value.Multiplying such a malformed zero value by another zero reached the negative-zero check in
decimal_mul, where there were no digit words to scan, leading to assertion failure.Fix:
Fix
do_div_mod, which produced the malformed zero.do_div_modalready normalizes this case to a canonical zero on the modulo path; do the same on the division path: when the quotient has no digits (intg0 == 0 && frac0 == 0) return a correct decimal zero instead of a digit-less, signed value.