[Tarantool-patches] [PATCH luajit] Limit exponent range in number parsing.

[Sergey Kaplun]

Hi, Sergey!
Thanks for the review!

Fixed you comment, see the patch below.
Branch is force-pushed.

On 25.01.24, Sergey Bronnikov wrote:
> Hi, Sergey!
> 
> thanks for the patch!
> 
> 
> On 1/24/24 00:14, Sergey Kaplun wrote:
> 
> 
> <snipped>
> 
> > +++ b/test/tarantool-tests/lj-788-limit-exponents-range.test.lua
> > @@ -0,0 +1,29 @@
> > +local tap = require('tap')
> > +
> > +-- Test file to demonstrate incorrect behaviour of exponent number
> > +-- form parsing.
> > +-- See also: https://github.com/LuaJIT/LuaJIT/issues/788.
> > +local test = tap.test('lj-788-limit-exponents-range')
> > +test:plan(2)
> > +
> > +-- Before the patch, the powers greater than (1 << 16) * 10
> > +-- (655360) were parsed incorrectly. After the patch, powers
> > +-- greater than 1 << 20 (1048576 `STRSCAN_MAXEXP`) are considered
> > +-- invalid. See <src/lj_strscan.c> for details.
> > +-- Choose the first value between these values and the second
> > +-- value bigger than `STRSCAN_MAXEXP` to check parsing correctness
> 
> typical values on testing boundaries [1] are: value before the boundary,
> 
> boundary value and value after the boundary. So I propose to test these 
> three values.
> 
> 1: https://en.wikipedia.org/wiki/Boundary-value_analysis

Thanks! Good to know:).

I added the boundary test case and updated tests names as you suggested.

===================================================================
diff --git a/test/tarantool-tests/lj-788-limit-exponents-range.test.lua b/test/tarantool-tests/lj-788-limit-exponents-range.test.lua
index 8ab31600..0af584fd 100644
--- a/test/tarantool-tests/lj-788-limit-exponents-range.test.lua
+++ b/test/tarantool-tests/lj-788-limit-exponents-range.test.lua
@@ -4,7 +4,7 @@ local tap = require('tap')
 -- form parsing.
 -- See also: https://github.com/LuaJIT/LuaJIT/issues/788.
 local test = tap.test('lj-788-limit-exponents-range')
-test:plan(2)
+test:plan(3)
 
 -- Before the patch, the powers greater than (1 << 16) * 10
 -- (655360) were parsed incorrectly. After the patch, powers
@@ -14,6 +14,7 @@ test:plan(2)
 -- value bigger than `STRSCAN_MAXEXP` to check parsing correctness
 -- for the first one, and `STRSCAN_ERROR` for the second case.
 local PARSABLE_EXP_POWER  = 1000000
+local STRSCAN_MAXEXP      = 1048576
 local TOO_LARGE_EXP_POWER = 1050000
 
 local function form_exp_string(n)
@@ -21,9 +22,12 @@ local function form_exp_string(n)
 end
 
 test:is(tonumber(form_exp_string(PARSABLE_EXP_POWER)), 1,
-        'correct parsing of large exponent')
+        'correct parsing of large exponent before the boundary')
+
+test:is(tonumber(form_exp_string(STRSCAN_MAXEXP)), nil,
+        'boundary power of exponent is not parsed')
 
 test:is(tonumber(form_exp_string(TOO_LARGE_EXP_POWER)), nil,
-        'too big exponent power is not parsed')
+        'too big exponent power after the boundary is not parsed')
 
 test:done(true)
===================================================================

> 
> > +-- for the first one, and `STRSCAN_ERROR` for the second case.
> > +local PARSABLE_EXP_POWER  = 1000000
> > +local TOO_LARGE_EXP_POWER = 1050000
> > +
> > +local function form_exp_string(n)
> > +  return '0.' .. string.rep('0', n - 1) .. '1e' .. tostring(n)
> > +end
> > +
> > +test:is(tonumber(form_exp_string(PARSABLE_EXP_POWER)), 1,
> > +        'correct parsing of large exponent')
> > +
> > +test:is(tonumber(form_exp_string(TOO_LARGE_EXP_POWER)), nil,
> > +        'too big exponent power is not parsed')
> > +
> > +test:done(true)

-- 
Best regards,
Sergey Kaplun