fix: digest() drops final hash character when FNV tail value is zero - #37
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The tail1/tail2 values in digest() were checked with != 0 to determine if they held valid data. However, 0 is a valid FNV hash output that maps to b64[0]='A'. The C reference implementation stores b64[h] in its digest array and checks != '\0', which always passes for valid hash values. Added hasTail1/hasTail2 boolean flags to explicitly track whether tail values were set during a trigger at full digest capacity. Validated against the C reference (ssdeep-project/ssdeep) on 103,001 test files with zero mismatches. The unpatched code produces 75 mismatches, all following the same pattern: a trailing 'A' (b64[0]) dropped from the first hash part. Fixes glaslos#28
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The tail1/tail2 values in digest() were checked with != 0 to determine if they held valid data. However, 0 is a valid FNV hash output that maps to b64[0]='A'. The C reference implementation stores b64[h] in its digest array and checks != '\0', which always passes for valid hash values.
Added hasTail1/hasTail2 boolean flags to explicitly track whether tail values were set during a trigger at full digest capacity.
Validated against the C reference (ssdeep-project/ssdeep) on 103,001 test files with zero mismatches. The unpatched code produces 75 mismatches, all following the same pattern: a trailing 'A' (b64[0]) dropped from the first hash part.
Fixes #23