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

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

Thanks! LGTM now

On 1/25/24 13:06, Sergey Kaplun wrote:
> 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)