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leb128: avoid shifts larger than type (#123)

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Jacek Sieka 2022-07-16 19:16:11 +02:00 committed by GitHub
parent b55c5a6d74
commit 9a3130eb5b
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@ -109,6 +109,11 @@ template read7(shift: untyped) =
if (shift div 7) >= xlen: if (shift div 7) >= xlen:
return (I(0), 0'i8) # Not enough data - return 0 bytes read return (I(0), 0'i8) # Not enough data - return 0 bytes read
when shift >= sizeof(I) * 8:
# avoid shift overflows: https://github.com/nim-lang/Nim/issues/19983
if true:
return (I(0), -cast[int8]((shift div 7) + 1))
let let
b = x[shift div 7] b = x[shift div 7]
valb = b and 0x7f'u8 # byte without high bit valb = b and 0x7f'u8 # byte without high bit