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

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

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)
-- 
2.41.0