[Tarantool-patches] [PATCH luajit] Give expected results for negative non-base-10 numbers in tonumber().

[sergos]

Hi!

Thanks for the patch!

LGTM
Sergos

> On 27 Dec 2021, at 16:42, Sergey Kaplun <skaplun at tarantool.org> wrote:
> 
> From: Mike Pall <mike>
> 
> This was undefined in Lua 5.1, but it's defined in 5.2.
> 
> (cherry picked from f3cf0d6e15240098147437fed7bd436ff55fdf8c)
> 
> `strtoul()` considers negative values as a valid input and silently
> converts them to the equivalent unsigned long value. As a result yielded
> value is unexpected to the user.
> 
I believe a missing point here is ‘equivalent’ become an ‘unexpected’ after
being converted into a number - namely, floating point. 

> This patch adds reading of a sign (if exists) from argument and provide
> the remaining part of the string as is if it starts with a digit or
> alphabetical symbol to be consistent with Lua 5.2.
> 
> Sergey Kaplun:
> * added the description and the test for the problem
> 
> Part of tarantool/tarantool#6548
> ---
> 
> Issue: https://github.com/tarantool/tarantool/issues/6548
> Branch: https://github.com/tarantool/luajit/tree/skaplun/gh-noticket-tonumber-expected-results-full-ci
> Tarantool branch: https://github.com/tarantool/tarantool/tree/skaplun/gh-noticket-tonumber-expected-results-full-ci
> 
> CI is red due to integration tests failes (same as on master) or due to
> connection errors.
> 
> Side note: I suppose that undefinence Mike talking about is the
> following lines in the Lua 5.1 Reference manual [1]:
> 
> | In base 10 (the default), the number can have a decimal part, as well
> | as an optional exponent part (see paragraph 2.1). In other bases, only
> | unsigned integers are accepted.
> 
> In the Lua 5.2 Reference manual [2] they are deleted.
> 
> src/lib_base.c                                | 27 +++++++++++------
> ...onumber-negative-non-decimal-base.test.lua | 29 +++++++++++++++++++
> 2 files changed, 47 insertions(+), 9 deletions(-)
> create mode 100644 test/tarantool-tests/tonumber-negative-non-decimal-base.test.lua
> 
> diff --git a/src/lib_base.c b/src/lib_base.c
> index 3a757870..d61e8762 100644
> --- a/src/lib_base.c
> +++ b/src/lib_base.c
> @@ -287,18 +287,27 @@ LJLIB_ASM(tonumber)		LJLIB_REC(.)
>   } else {
>     const char *p = strdata(lj_lib_checkstr(L, 1));
>     char *ep;
> +    unsigned int neg = 0;
>     unsigned long ul;
>     if (base < 2 || base > 36)
>       lj_err_arg(L, 2, LJ_ERR_BASERNG);
> -    ul = strtoul(p, &ep, base);
> -    if (p != ep) {
> -      while (lj_char_isspace((unsigned char)(*ep))) ep++;
> -      if (*ep == '\0') {
> -	if (LJ_DUALNUM && LJ_LIKELY(ul < 0x80000000u))
> -	  setintV(L->base-1-LJ_FR2, (int32_t)ul);
> -	else
> -	  setnumV(L->base-1-LJ_FR2, (lua_Number)ul);
> -	return FFH_RES(1);
> +    while (lj_char_isspace((unsigned char)(*p))) p++;
> +    if (*p == '-') { p++; neg = 1; } else if (*p == '+') { p++; }
> +    if (lj_char_isalnum((unsigned char)(*p))) {
> +      ul = strtoul(p, &ep, base);
> +      if (p != ep) {
> +	while (lj_char_isspace((unsigned char)(*ep))) ep++;
> +	if (*ep == '\0') {
> +	  if (LJ_DUALNUM && LJ_LIKELY(ul < 0x80000000u+neg)) {
> +	    if (neg) ul = -ul;
> +	    setintV(L->base-1-LJ_FR2, (int32_t)ul);
> +	  } else {
> +	    lua_Number n = (lua_Number)ul;
> +	    if (neg) n = -n;
> +	    setnumV(L->base-1-LJ_FR2, n);
> +	  }
> +	  return FFH_RES(1);
> +	}
>       }
>     }
>   }
> diff --git a/test/tarantool-tests/tonumber-negative-non-decimal-base.test.lua b/test/tarantool-tests/tonumber-negative-non-decimal-base.test.lua
> new file mode 100644
> index 00000000..94df3b1f
> --- /dev/null
> +++ b/test/tarantool-tests/tonumber-negative-non-decimal-base.test.lua
> @@ -0,0 +1,29 @@
> +local tap = require('tap')
> +
> +local test = tap.test('tonumber-negative-non-decimal-base')
> +test:plan(18)
> +
> +-- Test valid tonumber() with +- signs and non-10 base.
> +test:ok(tonumber('-010', 2) == -2, 'negative base 2')
> +test:ok(tonumber('-10', 8) == -8, 'negative base 8')
> +test:ok(tonumber('-0x10', 16) == -16, 'negative base 16')
> +test:ok(tonumber('  -1010  ', 2) == -10, 'negative base 2 with spaces')
> +test:ok(tonumber('  +1010  ', 2) == 10, 'positive base 2 with spaces')
> +test:ok(tonumber('  -012  ', 8) == -10, 'negative base 8 with spaces')
> +test:ok(tonumber('  +012  ', 8) == 10, 'positive base 8 with spaces')
> +test:ok(tonumber('  -10  ', 16) == -16, 'negative base 16 with spaces')
> +test:ok(tonumber('  +10  ', 16) == 16, 'positive base 16 with spaces')
> +test:ok(tonumber('  -1Z  ', 36) == -36 - 35, 'negative base 36 with spaces')
> +test:ok(tonumber('  +1z  ', 36) == 36 + 35, 'positive base 36 with spaces')
> +test:ok(tonumber('-fF', 16) == -(15 + (16 * 15)), 'negative base 16 mixed case')
> +test:ok(tonumber('-0ffffffFFFF', 16) - 1 == -2 ^ 40, 'negative base 16 long')
> +
> +-- Test invalid tonumber() for non-10 base.
> +test:ok(tonumber('-z1010  ', 2) == nil, 'incorrect notation in base 2')
> +test:ok(tonumber('--1010  ', 2) == nil, 'double minus sign')
> +test:ok(tonumber('-+1010  ', 2) == nil, 'minus plus sign')
> +test:ok(tonumber('- 1010  ', 2) == nil, 'space between sign and value')
> +test:ok(tonumber('-_1010  ', 2) == nil,
> +	'invalid character between sign and value')
> +
> +os.exit(test:check() and 0 or 1)
> -- 
> 2.34.1
> 
> [1]: http://www.lua.org/manual/5.1/manual.html#pdf-tonumber
> [2]: http://www.lua.org/manual/5.2/manual.html#pdf-tonumber