Lua: Fix bad bitshift in lua_strx2number() #14204
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The port of lua to OpenZFS modified lua to use int64_t for numbers instead of double. As part of this, a function for calculating exponentiation was replaced with a bit shift. Unfortunately, it did not handle negative values. Also, it only supported exponents numbers with 7 digits before before overflow. This supports exponents up to 15 digits before overflow. Clang's static analyzer reported this as "Result of operation is garbage or undefined" because the exponent was negative. Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
szubersk
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Nov 20, 2022
behlendorf
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Nov 29, 2022
tonyhutter
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Nov 29, 2022
The port of lua to OpenZFS modified lua to use int64_t for numbers instead of double. As part of this, a function for calculating exponentiation was replaced with a bit shift. Unfortunately, it did not handle negative values. Also, it only supported exponents numbers with 7 digits before before overflow. This supports exponents up to 15 digits before overflow. Clang's static analyzer reported this as "Result of operation is garbage or undefined" because the exponent was negative. Reviewed-by: Damian Szuberski <szuberskidamian@gmail.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu> Closes openzfs#14204
tonyhutter
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Nov 30, 2022
The port of lua to OpenZFS modified lua to use int64_t for numbers instead of double. As part of this, a function for calculating exponentiation was replaced with a bit shift. Unfortunately, it did not handle negative values. Also, it only supported exponents numbers with 7 digits before before overflow. This supports exponents up to 15 digits before overflow. Clang's static analyzer reported this as "Result of operation is garbage or undefined" because the exponent was negative. Reviewed-by: Damian Szuberski <szuberskidamian@gmail.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu> Closes openzfs#14204
tonyhutter
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Dec 1, 2022
The port of lua to OpenZFS modified lua to use int64_t for numbers instead of double. As part of this, a function for calculating exponentiation was replaced with a bit shift. Unfortunately, it did not handle negative values. Also, it only supported exponents numbers with 7 digits before before overflow. This supports exponents up to 15 digits before overflow. Clang's static analyzer reported this as "Result of operation is garbage or undefined" because the exponent was negative. Reviewed-by: Damian Szuberski <szuberskidamian@gmail.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu> Closes openzfs#14204
andrewc12
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Dec 16, 2022
The port of lua to OpenZFS modified lua to use int64_t for numbers instead of double. As part of this, a function for calculating exponentiation was replaced with a bit shift. Unfortunately, it did not handle negative values. Also, it only supported exponents numbers with 7 digits before before overflow. This supports exponents up to 15 digits before overflow. Clang's static analyzer reported this as "Result of operation is garbage or undefined" because the exponent was negative. Reviewed-by: Damian Szuberski <szuberskidamian@gmail.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu> Closes openzfs#14204
andrewc12
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Dec 17, 2022
The port of lua to OpenZFS modified lua to use int64_t for numbers instead of double. As part of this, a function for calculating exponentiation was replaced with a bit shift. Unfortunately, it did not handle negative values. Also, it only supported exponents numbers with 7 digits before before overflow. This supports exponents up to 15 digits before overflow. Clang's static analyzer reported this as "Result of operation is garbage or undefined" because the exponent was negative. Reviewed-by: Damian Szuberski <szuberskidamian@gmail.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu> Closes openzfs#14204
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Motivation and Context
The port of lua to OpenZFS modified lua to use int64_t for numbers instead of double. As part of this, a function for calculating exponentiation was replaced with a bit shift. Unfortunately, it did not handle negative values. Also, it only supported exponents numbers with 7 digits before before overflow. This supports exponents up to 15 digits before overflow.
Clang's static analyzer reported this as "Result of operation is garbage or undefined" because the exponent was negative.
Description
We switch to a division when the exponent is negative (while making the exponent positive for the bitshift). We also have it operate on a 64-bit 1ULL, rather than 1, which is 32-bit. This prevents overflows from happening before a 64-bit number would overflow.
How Has This Been Tested?
A build test has been done.
Types of changes
Checklist:
Signed-off-by.