Re: [Tarantool-patches] [PATCH luajit] Fix binary number literal parsing.

[Sergey Bronnikov via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Sergey, thanks for the patch! LGTM. Sergey

On 8/24/23 13:02, Sergey Kaplun wrote:
> From: Mike Pall <mike>
>
> Reported by Egor Skriptunoff.
>
> (cherry-picked from commit 377a8488b62a9f1b589bb68875dd1288aa70e76e)
>
> Binary number with fractional part is invalid. Parsing of such binary
> numbers returns `STRSCAN_ERROR` for any numbers with non-zero fractional
> part, because it gives non-zero power of the exponent (`ex2`) in
> `strscan_bin()`. But binary numbers with a zero fractional part
> considered as valid numbers. To avoid such inconsistency the check, that
> the given base doesn't equal 2, is added, when parsing decimal point
> part of the literal.
>
> Sergey Kaplun:
> * added the description and the test for the problem
>
> Part of tarantool/tarantool#8825
> ---
>
> Branch: https://github.com/tarantool/luajit/tree/skaplun/fix-binary-number-parsing
> Issue: https://github.com/tarantool/tarantool/issues/8825
> ML: https://www.freelists.org/post/luajit/Fractional-binary-number-literals
> Tarantool PR: https://github.com/tarantool/tarantool/pull/9028
>
> Tarantool's CI is red, because static build on aarch64 can't fetch the
> LuaJIT's submodule commit somehow. Looks unrelated to the commit:).
>
>   src/lj_strscan.c                                |  1 +
>   .../fix-binary-number-parsing.test.lua          | 17 +++++++++++++++++
>   2 files changed, 18 insertions(+)
>   create mode 100644 test/tarantool-tests/fix-binary-number-parsing.test.lua
>
> diff --git a/src/lj_strscan.c b/src/lj_strscan.c
> index 11d341ee..a2d92714 100644
> --- a/src/lj_strscan.c
> +++ b/src/lj_strscan.c
> @@ -444,6 +444,7 @@ StrScanFmt lj_strscan_scan(const uint8_t *p, MSize len, TValue *o,
>   
>       /* Handle decimal point. */
>       if (dp) {
> +      if (base == 2) return STRSCAN_ERROR;
>         fmt = STRSCAN_NUM;
>         if (dig) {
>   	ex = (int32_t)(dp-(p-1)); dp = p-1;
> diff --git a/test/tarantool-tests/fix-binary-number-parsing.test.lua b/test/tarantool-tests/fix-binary-number-parsing.test.lua
> new file mode 100644
> index 00000000..df82bd0b
> --- /dev/null
> +++ b/test/tarantool-tests/fix-binary-number-parsing.test.lua
> @@ -0,0 +1,17 @@
> +local tap = require('tap')
> +
> +-- Test file to demonstrate incorrect behaviour of binary number
> +-- parsing with fractional dot.
> +-- See also:
> +-- https://www.freelists.org/post/luajit/Fractional-binary-number-literals
> +local test = tap.test('fix-binary-number-parsing')
> +test:plan(2)
> +
> +-- Test that incorrect literal with non-0 fractional part still
> +-- can't be converted to number.
> +test:is(tonumber('0b.1'), nil, '0b.1 is not converted')
> +-- Test that incorrect literal with 0 fractional part can't be
> +-- converted to number.
> +test:is(tonumber('0b.0'), nil, '0b.0 is not converted')
> +
> +test:done(true)